View Full Version : [Space] NASA-ESA - Cassini-Hyugens
Cassini-Hyugens è la prima missione scientifica interplanetaria congiunta tra più agenzie spaziali: NASA ed ESA, e l'italiana ASI.
Si tratta di una navetta interstellare, la più grande mai costruita, composta da un'orbiter (Cassini, NASA) e da una sonda (Hyugens, ESA). Per la prima volta nella storia una sonda atterrerà su un asteroide del sistema solare esterno.
http://www.esa.int/export/images/huygens3,4.jpg
Dal sito NASA della missione, http://saturn.jpl.nasa.gov/index.cfm:
With its stunning rings and dozen of moons, Saturn is an intriguing planet for many reasons. Barely smaller than Jupiter, it formed four billion years ago and it is made mainly of gas. It is also the only known planet that is less dense than water, meaning that if it could be placed inside an imaginary gigantic bathtub it would float. Saturn has a huge magnetosphere and a stormy atmosphere, with winds clocked at 1,800 kilometers (1,118 miles) per hour near its equator.
Of the 31 known moons orbiting Saturn, Titan is the largest. Bigger than the planet Mercury and our own moon, Titan is of particular interest to scientists because it is the only moon in the solar system with its own atmosphere.
But what sets Saturn apart from the rest of the planets in the solar system are its picturesque rings. Made up by billions of ice and rock particles of all sizes -- from small debris to boulders as big as houses -- these rings orbit Saturn at varying speeds. There are hundreds of these rings, believed to be pieces of shattered comets, asteroids or moons that broke apart before they reached the planet. The rings are so big that they would fill most of the distance between Earth and the Moon.
For centuries, Saturn and its rings puzzled observers, in particular, Italian astronomer Galileo Galilei. The first to use a telescope to explore the wonders of the heavens, Galileo couldn't understand why Saturn looked different in the night sky at varying times-- a phenomenon that we now know is caused by the shifting of our view of the ring plane. Because of this, when the rings face Earth edge-on they are virtually invisible. They seem to reappear months later when our angle of view changes. Despite major advances in lens technology since Galileo's time, many questions still need to be answered through exploration of Saturn's rings.
Launched from Kennedy Space Center on Oct. 15, 1997, the Cassini-Huygens spacecraft will reach the Saturnian region in July 2004. The mission is composed of two elements: The Cassini orbiter that will orbit Saturn and its moons for four years, and the Huygens probe that will dive into the murky atmosphere of Titan and land on its surface. The sophisticated instruments onboard these spacecraft will provide scientists with vital data to help understand this mysterious, vast region.
Cassini-Huygens is an international collaboration between three space agencies. Seventeen nations contributed to building the spacecraft. The Cassini orbiter was built and managed by NASA's Jet Propulsion Laboratory. The Huygens probe was built by the European Space Agency. The Italian Space agency provided Cassini's high-gain communication antenna. More than 200 scientists worldwide will study the data collected.
Dal sito ESA della missione, http://www.esa.int/export/esaSC/120378_index_0_m.html:
Mission
Huygens will be the first probe to land on a world in the outer Solar System - on the surface of Titan, Saturn’s largest moon. The Huygens data may offer clues about how life began on Earth. Huygens is currently in space, hitching a ride on NASA’s Cassini spacecraft.
While the Cassini orbiter continues to explore Saturn and its rings, the Huygens probe will be released to parachute through the atmosphere of Titan. Shrouded in an orange haze that hides its surface, Titan is one of the most mysterious objects in our solar system. It is the second largest moon (only Jupiter's Ganymede is bigger), and the only one with a thick atmosphere. It is this atmosphere that excites scientific interest, since it is thought to resemble that of a very young Earth.
Huygens's six instruments will take measurements throughout its descent, providing details on the chemical composition of Titan's atmosphere, its weather and clouds, and then the surface itself. Spectacular data and images are already expected from the descent and, if the Huygens probe survives the impact with the mysterious surface, it will continue to send unique information back to the Cassini orbiter until its batteries expire or it is out of range.
What's special?
Huygens's goals are to study the atmosphere and the surface of Titan along the descent ground track and near the landing site.
The Huygens instruments will make detailed on-the-spot measurements of Titan's atmospheric, looking at its structure, composition and dynamics. Images and other remote-sensing measurements of the surface of Titan will also be made during the descent.
After a descent of about 137 minutes, the probe will impact the surface at about 5-6 metres per second. It is hoped that the probe will survive this impact for at least a few minutes and that the instruments are also able to make direct measurements of the state and composition of the landing site surface.
Preserved in the deep freeze of Titan's atmosphere are chemical, carbon-rich compounds thought to be similar to those of Earth's primeval soup. The in-situ results from Huygens, combined with Cassini's global observations from repeated flybys of Titan, will provide vital information towards the great mystery of how life began on Earth.
Spacecraft
The first element of the Huygens system consists of the 318-kilogram Huygens probe itself, which enters Titan's atmosphere after separating from the Cassini orbiter. It consists of two parts: the Entry Assembly (ENA) which cocoons the Descent Module (DM).
The ENA connects the Huygens probe to the Cassini orbiter until it initiates and performs the ejection of the probe. It then controls the cruise to Titan, provides thermal protection during entry and the parachutes decelerate the probe in time for the landing on Titan. It is then jettisoned, releasing the DM.
The DM comprises an aluminium shell and inner structure containing all the experiments and probe support subsystems, including the parachute descent and spin control devices.
The second element of the Huygens system is the 30-kilogram Probe Support Equipment (PSE), which remains attached to the orbiter after probe separation.
The PSE consists of four electronic boxes aboard the orbiter providing control and communications. It provides power and data links between the probe and orbiter before the probe is launched.
Journey
The large Cassini/Huygens spacecraft used four gravity-assist swing-by manoeuvres: Venus (April 1998), Venus (June 1999), Earth (August 1999) and Jupiter (December 2000) on its journey towards Saturn and Titan. In early 2005, towards the end of Cassini's third orbit around Saturn, the Huygens probe is ejected on a 22-day cruise to Titan.
History
The development of the Cassini/Huygens mission, a complex and ambitious venture between NASA and ESA, required substantial scientific, technical and programme planning efforts over several years. In the late 1970s, NASA studied several scenarios for a mission to Saturn as the next natural step after the Galileo orbiter/probe mission to Jupiter in the detailed exploration of the giant planets.
The Cassini mission was originally proposed in November 1982 by a team of European and American scientists as a collaborative initiative with NASA in response to a regular call for mission ideas by ESA.
Very early in the study phase, the Titan probe was identified as ESA’s potential contribution to the international Cassini mission. It was within the technical capabilities of the European space industry, which had limited experience in planetary missions, mainly acquired with the Giotto mission.
During the evaluation studies, the need for using planetary gravity-assist manoeuvres was identified in order to send the spacecraft towards Saturn, as no launcher existed that was powerful enough to send it directly to Saturn. Three launch opportunities were identified; each included a Jupiter fly-by in addition to Venus and Earth fly-bys. A fly-by of Jupiter is required to reach Saturn in a reasonable time: 6.7 years, instead of 9–10 years.
The Titan probe was named Huygens in honour of the Dutch astronomer who discovered Titan in 1655.
Partnerships
There are six instruments on board the Huygens probe, each developed by different teams.
The Huygens Atmosphere Structure Instrument comprises sensors for measuring the physical and electrical properties of the atmosphere and an on-board microphone that will send back sounds from Titan. This is led by the Université de Paris VII, Observatoire de Paris-Meudon, France, with contributions from Italy, Austria, Germany, Spain, France, the United Kingdom, Norway, Finland, and the United States.
The Gas Chromatograph and Mass Spectrometer is a versatile gas chemical analyser designed to identify and quantify various atmospheric constituents. It is also equipped with gas samplers which will be filled at high altitude for analysis later in the descent when more time is available. This is led by NASA and supported by contributions from the Austria and France.
The Aerosol Collector and Pyrolyser will collect aerosols for chemical-composition analysis. After extension of the sampling device, a pump will draw the atmosphere through filters which capture aerosols. Each sampling device can collect about 30 micrograms of material. This is managed by the French CNRS Service d'Aéronomie, with support from Austria and the United States.
The Descent Imager/Spectral Radiometer can take images and make spectral measurements using sensors covering a wide spectral range. A few hundred metres before impact, the instrument will switch on its lamp in order to acquire spectra of the surface material. This is provided by the University of Arizona, United States, with support from Germany and France.
The Doppler Wind Experiment uses radio signals to deduce atmospheric properties. The probe drift caused by winds in Titan's atmosphere will induce a measurable Doppler shift in the carrier signal. The swinging motion of the probe beneath its parachute and other radio-signal-perturbing effects, such as atmospheric attenuation, may also be detectable from the signal. This is managed by the Universität Bonn, Germany, with collaboration from Italy and the United States.
The Surface-Science Package is a suite of sensors to determine the physical properties of the surface at the impact site and to provide unique information about its composition. The package includes an accelerometer to measure the impact deceleration, and other sensors to measure the index of refraction, temperature, thermal conductivity, heat capacity, speed of sound, and dielectric constant of the (liquid) material at the impact site. The Open University, United Kingdom, manages this with support from ESA, Italy and the United States.
Huygens factsheet
Landing on Titan, Saturn's mysterious moon
Name: Christiaan Huygens (1629-1695) was a Dutch astronomer who discovered Saturn's rings and, in 1655, its largest moon, Titan.
Description: Huygens will be the first probe to land on a world in the outer Solar System - on the surface of Titan, Saturn’s largest moon. Data from Huygens may offer clues about how life began on Earth. Huygens is currently in space, hitching a ride on NASA’s Cassini spacecraft.
Launch 15 October 1997 (Titan-IVB/Centaur at Cape Canaveral, United States).
Status In operation - due to arrive at Titan in early 2005.
Journey The 5.6-tonne Cassini/Huygens spacecraft did four gravity-assist swing-by manoeuvres. These manoeuvres were: Venus (April 1998), Venus (June 1999), Earth (August 1999), and Jupiter (December 2000). In December 2004, towards the end of Cassini's third orbit around Saturn, the Huygens probe will be ejected on a 22-day cruise to Titan. Huygens is due to reach Titan on 14 January 2005.
Notes Cassini/Huygens is the largest interplanetary spacecraft ever built.
Gravity-assists from two swing-bys of Venus and one of Earth provide the equivalent of 68 040 kilograms of rocket fuel.
It is dormant during the long journey to Saturn, so ESA scientists 'wake up' Huygens every six months to check that all is well.
The Huygens probe can withstand temperatures of up to 18 000°C in front of the heat shield. The heat generated as Huygens travels through Titan's thick gas atmosphere will be immense.
Titan is one of the most mysterious objects in our Solar System. It is the second largest moon and the only one with a thick, methane-rich, nitrogen atmosphere. Experts think that its atmosphere resembles that of a very young Earth.
La navetta Cassini con la sonda Hyugens:
http://saturn.jpl.nasa.gov/spacecraft/images/spacecraft-litho.jpg
Fradetti
18-01-2004, 12:15
:cool: Io al Cassini ci studio :cool:
Getting closer to the Lord of the Rings
16 January 2004
This time next year, ESA’s Huygens spaceprobe will be descending through the atmosphere of Saturn’s largest moon, becoming the first spacecraft to land on a body in the outer Solar System.
Earlier this month, the giant ringed planet Saturn was closer to Earth than it will be for the next thirty years. All the planets orbit the Sun as if on a giant racetrack, travelling in the same direction but in different lanes.
Those in the outer lanes have further to travel than those on the inside lanes. So, Earth regularly ‘laps’ the further planets. On New Year’s Eve 2003, Earth overtook Saturn, drawing closer than at any time in the next three decades.
Through a small telescope, Saturn is normally visible as a creamy yellow ‘star’. You may be able to see the ring system that the planet is famous for, and its largest moon Titan will show up as a tiny dot of light.
That tiny dot is the destination for ESA’s Huygens probe and may hold vital clues about how life began on Earth. Titan is the only moon with a thick atmosphere in the Solar System.
Astronomers think this atmosphere might closely match the one Earth possessed millions of years ago, before life began. Certainly Titan’s atmosphere is rich in carbon, the chemical necessary for life on Earth. What is more, this is all stored in ‘deep freeze’, ten times further from the Sun than the Earth.
The big mystery is Titan’s surface, which is hidden by a cloud layer. This is why ESA built Huygens, to probe through this layer which is impenetrable by Earth-based observations.
In January 2005, Huygens will parachute below the clouds to see what is really going on. Its battery of instruments will return over 1000 images as it floats down and samples the chemistry of this exotic place.
The Titan probe was named Huygens in honour of the Dutch astronomer who discovered Titan in 1655. Launched in October 1997, Huygens is currently in space, hitching a ride on NASA’s Cassini spacecraft.
So look forward to seeing more of Saturn and a tiny European spacecraft called Huygens, that in one year’s time will make an historic landing in the quest to uncover the origins of life.
Note:
La dimensione e l'obiettivo di Cassini-Huygens (Saturno-Titano) ha richiesto l'uso del più potente lanciatore espandibile al mondo, il Titan IV/Centaur, ma questo non basta a lanciare direttamente la navetta verso la sua destinazione, è stata quindi studiata una traiettoria unica nel suo genere che ha previsto lo sfruttamento della forza gravitazionale di Venere (2 passaggi, 1998-99) e della Terra (2001).
Cassini usa come le precedenti sonde interplanetarie e navette Apollo, Viking, Pioneer e Voyager o le attuali Galileo e Ulysses, un generatore termoelettrico a radioisotopi (RTG) per produrre energia elettrica necessaria a missioni lunghe parecchi anni.
Un RTG non è un reattore nucleare, e non sfrutta nè processi di fissione nè di fusione nucleare, bensì genera calore con la naturale decadenza radioattiva dell'isotopo plutonio-238 (non adatto ad uso militare). Il calore così prodotto è convertito in elettricità da convertitori termoelettrici a stato solido.
http://saturn.jpl.nasa.gov/spacecraft/images/rtgcutout.jpg
Originariamente inviato da GioFX
Note:
La dimensione e l'obiettivo di Cassini-Huygens (Saturno-Titano) ha richiesto l'uso del più potente lanciatore espandibile al mondo, ma questo non basta a lanciare direttamente la navetta verso la sua destinazione, è stata quindi studiata una traiettoria unica nel suo genere che ha previsto lo sfruttamento della forza gravitazionale di Venere (2 passaggi, 1998-99) e della Terra (2001).
Cassini usa come le precedenti sonde interplanetarie e navette Apollo, Viking, Pioneer e Voyager o le attuali Galileo e Ulysses, un generatore termoelettrico a radioisotopi (RTG) per produrre energia elettrica necessaria a missioni lunghe parecchi anni.
Un RTG non è un reattore nucleare, e non sfrutta nè processi di fissione nè di fusione nucleare, bensì generano calore con la naturale decadenza radioattiva dell'isotopo plutonio-238 (non adatto ad uso militare). Il calore così prodotto è convertito in elettricità da convertitori termoelettrici a stato solido.
http://saturn.jpl.nasa.gov/spacecraft/images/rtgcutout.jpg
:eek:
troppo fico
jumpermax
18-01-2004, 14:31
Originariamente inviato da GioFX
Note:
La dimensione e l'obiettivo di Cassini-Huygens (Saturno-Titano) ha richiesto l'uso del più potente lanciatore espandibile al mondo, ma questo non basta a lanciare direttamente la navetta verso la sua destinazione, è stata quindi studiata una traiettoria unica nel suo genere che ha previsto lo sfruttamento della forza gravitazionale di Venere (2 passaggi, 1998-99) e della Terra (2001).
Cassini usa come le precedenti sonde interplanetarie e navette Apollo, Viking, Pioneer e Voyager o le attuali Galileo e Ulysses, un generatore termoelettrico a radioisotopi (RTG) per produrre energia elettrica necessaria a missioni lunghe parecchi anni.
Un RTG non è un reattore nucleare, e non sfrutta nè processi di fissione nè di fusione nucleare, bensì generano calore con la naturale decadenza radioattiva dell'isotopo plutonio-238 (non adatto ad uso militare). Il calore così prodotto è convertito in elettricità da convertitori termoelettrici a stato solido.
http://saturn.jpl.nasa.gov/spacecraft/images/rtgcutout.jpg
infatti c'è tutto una serie di documenti che spiega come questi generatori siano indispensabili per le missioni oltre marte. Per funzionare ad energia solare Cassini avrebbe dovuto avere dei pannelli solari di 500m^2...
spinbird
18-01-2004, 14:33
nel 96-97 avevo molto seguito la cotruzione della sonda tutto il progetto generale...non vedo l'ora che arrivi:)
ominiverdi
18-01-2004, 14:35
ok, potrei dire una cavolata, ma un generatore a radioisotopi visto la sua longevita', non potrebbe essere adattato per alimentare pc portatili, cellulari e altri apparecchi domestici?
costerebbe troppo? troppo pericoloso?
jumpermax
18-01-2004, 15:00
Originariamente inviato da ominiverdi
ok, potrei dire una cavolata, ma un generatore a radioisotopi visto la sua longevita', non potrebbe essere adattato per alimentare pc portatili, cellulari e altri apparecchi domestici?
costerebbe troppo? troppo pericoloso?
mmmh dico... già abbiamo problemi a smaltire le batterie agli ioni di litio... te le immagini le batterie all'uranio238? E secondo te poi la gente la farebbe la raccolta differenziata? Come no...
Senza considerare che
io un cellulare con una batteria all'uranio per quanto sicuro non me lo metterei all'orecchio...
Per quel tipo di prodotti il futuro saranno le batterie a celle combustibili. I portatili avranno un'autonomia di qualche giorno i cellulari forse anche un paio di settimane... oltretutto meno problemi di smaltimento.
ominiverdi
18-01-2004, 15:07
in effetti era un paragone azzardato, ma sarebbe fantastico poter usufruire di batterie con quella durata :eek:
tocchera' aspettare le batterie celle combustubili...
Originariamente inviato da ominiverdi
in effetti era un paragone azzardato, ma sarebbe fantastico poter usufruire di batterie con quella durata :eek:
e per fare cosa? che ti serve una generatore che dura dai 30 ai 100 anni con la durata media di un HW? senza contare il costo spropositato rispetto alla normale alimentazione a batterie o dalla rete elettrica e i problemi nello smaltimento...
Originariamente inviato da ominiverdi
ok, potrei dire una cavolata, ma un generatore a radioisotopi visto la sua longevita', non potrebbe essere adattato per alimentare pc portatili, cellulari e altri apparecchi domestici?
costerebbe troppo? troppo pericoloso?
eh eh...
magari.
pensa allora alle macchine elettriche...:eek: :D
Originariamente inviato da GioFX
e per fare cosa? che ti serve una generatore che dura dai 30 ai 100 anni con la durata media di un HW? senza contare il costo spropositato rispetto alla normale alimentazione a batterie o dalla rete elettrica e i problemi nello smaltimento...
beh, potrebbero fare batterie semi eterne...
e adeguare gli strumenti a quelle...
ovviamente se non ci fossero i rpoblemi costi-pericolosita':)
On Final Approach, Cassini Photographs Saturn
By Robert Roy Britt
Senior Science Writer
posted: 09:46 am ET
27 February 2004
The Cassini spacecraft has returned a detailed new picture of Saturn as the craft makes its final approach toward the ringed planet. The image is the first of many that should now begin to flow from the mission.
"Prepare to be amazed," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, CO.
In the new photograph, Saturn is 60 percent larger than it was in the last Cassini image, made in December. Details are visible in the planet's rings and clouds. And already scientists have found a puzzle.
There is a "noticeable absence" of ghostly, spoke-like dark markings in the rings. The features were discovered during the approach of the Voyager probe 23 years ago. Porco said this new puzzle is one of many in store for the mission.
The origin of the rings is itself a mystery.
Porco said images will now be released weekly, then more frequently starting in late May.
The spacecraft will enter orbit around Saturn on July 1. The mission will explore the planet's atmosphere and its rings and moons. Scientists expect to find previously unknown moons embedded in the rings, which contain icy particles from dust-grain size up to rocks and boulders.
On May 18, Cassini will enter the Saturn system, passing a group of outer moons as the gravitational pull of the giant planet begins to overpower that of the Sun. Observations of Saturn's largest moon, Titan, will begin a few days later.
On June 11, Cassini will photograph the moon Phoebe during a flyby. Phoebe is 137 miles (220 kilometers) wide, the largest of Saturn's outer moons and probably a captured asteroid.
Cassini launched in 1997. To save fuel and money, it made several planetary flybys to get speed boosts by stealing a little orbital energy from the planets. It looped around Venus twice, then flew past Earth. Later it studied and photographed Jupiter while getting a final push toward Saturn.
The spacecraft will release its piggybacked Huygens probe about six months after arriving at Saturn. Huygens will descend through the thick atmosphere of Titan on Jan. 14, 2005.
The new image was taken Feb. 9 and released today. Cassini was 43.1 million miles (69.4 million kilometers) from Saturn. The image contrast and colors have been slightly enhanced to improve visibility.
The icy moon Enceladus is faintly visible to the left, outside the rings. Enceladus is about 323 miles (520 kilometers) wide. Its brightness has been increased seven times relative to the planet, in order to make it noticeable. Cassini will investigate the moon more closely later in the mission.
Cassini has traveled 2.1 billion miles (3.4 billion kilometers) on its looping path. The mission is a cooperative effort of NASA, the European Space Agency and the Italian Space Agency.
http://www.space.com/images/0402327_cassini_image_02.jpg
This picture of Saturn was taken by Cassini on Feb. 9 and released Feb. 27. Notably absent are spokes in the rings seen by the Voyager spacecraft.
jumpermax
29-03-2004, 01:16
immagini di saturno in movimento...
High Winds Aloft on Saturn
March 26, 2004 Animated GIF (382 kB)
Full-Res: PIA05384
Wind-blown clouds and haze high in Saturn's atmosphere are captured in a movie made from images taken by the Cassini narrow angle camera between Feb. 15 and Feb. 19, 2004.
The bright areas in these images represent high haze and clouds near the top of Saturn's troposphere. Cassini has three filters designed to sense different heights of clouds and haze in the planet’s atmosphere. Any light detected by cameras using the 889-nanometer filter is reflected very high in the atmosphere, before the light is absorbed.
This is the first movie ever made showing Saturn in these near-infrared wavelengths. The images were made using a filter sensitive to a narrow range of wavelengths centered at 889-nanometers, where methane in Saturn's atmosphere absorbs sunlight.
In the movie, atmospheric motions can be seen most clearly in the equatorial region and at other southern latitudes. Saturn's equatorial region seems disturbed in the same way that it has been for the past decade, as revealed by observations from NASA’s Hubble Space Telescope. Researchers have speculated that the bright cloud patterns there are associated with water-moist convection arising from a deeper atmospheric level where water condenses on Saturn, and rising to levels at or above the visible cloud tops. Close analysis of future data by scientists on the Cassini-Huygens mission should help determine whether this is the case.
Saturn's rings are extremely overexposed in these images. Because the range of wavelengths for this spectral filter is narrow, and because most of this light is absorbed by Saturn, the disc of Saturn is inherently faint and the exposures required are quite long (22 seconds). The rings do not strongly absorb at these wavelengths, so they reflect more light and are overexposed compared to the atmosphere. Orbiting moons in the images were manually removed during processing.
The movie, consisting of 30 stacked images, spans five days and captures five complete but non-consecutive Saturn rotations. The direction of motion is from left to right. Each 10.6-hour Saturn rotation is evenly sampled by six images. After each rotation sequence, the planet can be seen to grow slightly in the field of view.
Cassini was 65.6 million kilometers (40.7 million miles) from Saturn when the images, reduced in scale by a factor of two onboard the spacecraft, were taken. The resulting image scale is approximately 786 kilometers (420 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.
For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .
Image Credit:
NASA/JPL/Space Science Institute
http://saturn.jpl.nasa.gov/multimedia/images/saturn/images/PIA05384.gif
Ocean waves forecast for Saturn's moon Titan
ROYAL ASTRONOMICAL SOCIETY NEWS RELEASE
Posted: March 31, 2004
http://www.spaceflightnow.com/news/n0308/30titan/huygens.jpg
When the European Huygens probe on the Cassini space mission parachutes down through the opaque smoggy atmosphere of Saturn's moon Titan early next year, it may find itself splashing into a sea of liquid hydrocarbons.
In what is probably the first piece of "extraterrestrial oceanography" ever carried out, Dr Nadeem Ghafoor of Surrey Satellite Technology and Professor John Zarnecki of the Open University, with Drs Meric Srokecz and Peter Challenor of the Southampton Oceanography Centre, calculated how any seas on Titan would compare with Earth's oceans. Their results predict that waves driven by the wind would be up to 7 times higher but would move more slowly and be much farther apart.
Dr Ghafoor will present their findings at the RAS National Astronomy Meeting at the Open University on Wednesday.
The team worked with a computer simulation, or 'model', that predicts how wind-driven waves on the surface of the sea are generated on Earth, but they changed all the basic inputs, such as the local gravity, and the properties of the liquid, to values they might expect on Titan.
Arguments about the nature of Titan's surface have raged for a number of years. Following the flyby of the Voyager 1 spacecraft in 1980, some researchers suggested that Titan's concealed surface might be at least partly covered by a sea of liquid methane and ethane. But there are several other theories, ranging from a hard icy surface at one extreme to a near-global hydrocarbon ocean at the other. Other variants include the notion of hydrocarbon 'sludge' overlying an icy surface.
Planetary scientists hope that the Cassini/Huygens mission will provide an answer to this question, with observations from Cassini during several flybys of Titan and from Huygens, which will land (or 'splash') on 14 January 2005.
The idea that Titan has significant bodies of surface liquid has recently been reinforced by the announcement that radar reflections from Titan have been detected using the giant Arecibo radio dish in Puerto Rico.
Importantly, the returned signals in 12 out the 16 attempts made contained reflections of the kind expected from a polished surface, like a mirror. (This is similar to seeing a blinding patch of light on the surface of the sea where the Sun is being reflected.) The radar researchers concluded that 75% of Titan's surface may be covered by 'open bodies of liquid hydrocarbons' -- in other words, seas.
The exact nature of the reflected radar signal can be used to determine how smooth or choppy the liquid surface is. This interpretation says that the slope of the waves is typically less than 4 degrees, which is consistent with the predictions of the British scientists, who showed that the maximum possible slope of waves generated by wind speeds up to 7 mph would be 11 degrees.
"Hopefully ESA's Huygens probe will end the speculation" says Dr Ghafoor. "Not only will this be by far the most remote soft landing of a spacecraft ever attempted but Huygens might become the first extraterrestrial boat if it does indeed land on a hydrocarbon lake or sea."
Although not designed specifically to survive landing or to float, the chances it will do so are reasonable. However, the link back to Earth from Huygens via Cassini, which will be flying past Titan and acting as a relay, will only last for a maximum of 2 hours. During this time, if the probe is floating on a sea, one of the 6 instruments Huygens is carrying, the Surface Science Package experiment, which is led by John Zarnecki, will be making oceanography measurements. Among the 9 sensors that it carries are ones that will measure the height and frequency of the waves and also the depth of the sea using sonar. It will also attempt to determine the composition of the sea.
What would the sea look like?
"Huygens does carry a camera so it is possible we shall have some direct images," says Professor Zarnecki, "but let's try to imagine that we are sitting onboard the probe after it has landed in a Titan ocean. What would we see? Well, the waves would be more widely dispersed than on Earth but they will be very much higher - mostly as a result of the fact that Titan gravity is only about 15% of that on Earth. So the surface around us would probably appear flat and deceptively calm, but in the distance we might see a rather tall, slow-moving wave advancing towards us -- a wave that could overwhelm or sink us."
jumpermax
01-04-2004, 01:36
questa missione se ha successo potrebbe quasi oscurare quella su Marte... chissà che paesaggio ci troveremo davanti su Titano? L'aspetto di marte in fin dei conti ci era noto... di Titano abbiamo solo le foto del voyager...
perdonatemi se vado offtopic, ma non volevo aprire una nuova discussione........
qualcuno qua saprebbe dirmi la velocità a cui atterra uno shuttle?
è una curiosità che mi devo levare :D
grazie :D
Originariamente inviato da riaw
perdonatemi se vado offtopic, ma non volevo aprire una nuova discussione........
qualcuno qua saprebbe dirmi la velocità a cui atterra uno shuttle?
è una curiosità che mi devo levare :D
grazie :D
cosa intendi per volocità di atterraggio, nel momento del touch down?
Lo Shuttle viagga così:
- 26,500 km/h poco prima dell'ingresso in atmosfera (T-60min al touch down, 282 km di altezza)
- Poco meno di 26,000 km/h al momento dell'Entry Interface (T-31min, h = 122 km)
- 24,200 km/h al momento del maximum heating (T-20min, h = 70 km)
- 13,320 km/h al momento di uscita dal blackout (T-12min, h = 55 km)
- 2,735 km/h alla Terminal Area (T-5,5min, h = 25,338 m)
- 682 km/h durante l'Approach and Landing (T-86s, h = 3 km)
- 565 km/h al momento dell'Initiate Preflare (T-32s, h = 533m)
- 496 km/h al Complete Preflare (T-17s, h = 41m)
- 430 km/h alla uscita carrello (Wheel down, T-14s, h = 27m)
- 346 km/h al Touchdown
Originariamente inviato da GioFX
- 346 km/h al Touchdown
intendevo questa :D
c'erano amici che sostenevano che atterra sui 180-200 orari, ma secondo me era un po impossibile :D
avevo scommesso sui 400, non ci sono andato lontanissimo ;)
Originariamente inviato da riaw
intendevo questa :D
c'erano amici che sostenevano che atterra sui 180-200 orari, ma secondo me era un po impossibile :D
avevo scommesso sui 400, non ci sono andato lontanissimo ;)
infatti, andrebbe in stallo a quella velocità, considerando la scarsa apertura alare...
Closing In: Saturn Fills Cassini Craft's Viewfinder
By SPACE.com Staff
posted: 09:40 am ET
29 April 2004
A portion of the rings of Saturn will be lopped off in the next portrait sent home by the Cassini spacecraft. The probe is so close to Saturn that in its most recent image, released today, the planet and rings fill the full frame.
Cassini goes into orbit around Saturn on July 1. The latest image, a natural color view from the narrow angle camera, was taken March 27 when the spacecraft was 29.7 million miles (47.7 million kilometers) from the planet.
A bright blue sliver of light in the northern hemisphere is sunlight passing through the Cassini Division in Saturn's rings and being scattered by the cloud-free upper atmosphere.
In the southern hemisphere, two faint dark spots are visible. These spots are close to the latitude where Cassini saw two storms merging in an image released earlier this month. The fate of the storms in the new image is unclear, scientists said. The spots getting close and will eventually merge or squeeze past each other.
Cassini launched in 1997. To save fuel and money, it made several planetary flybys to get speed boosts by stealing a little orbital energy from the planets. It looped around Venus twice, then flew past Earth. Later it studied and photographed Jupiter while getting a final push toward Saturn.
On May 18, Cassini will enter the Saturn system, passing a group of outer moons as the gravitational pull of the giant planet begins to overpower that of the Sun. Observations of Saturn's largest moon, Titan, will begin a few days later.
The spacecraft will release its piggybacked Huygens probe about six months after arriving at Saturn. Huygens will descend through the thick atmosphere of Titan on Jan. 14, 2005.
The mission is a cooperative effort of NASA, the European Space Agency and the Italian Space Agency. The imaging team is based at the Space Science Institute, Boulder, Colorado.
Mission officials said last week that the spacecraft is in excellent health and operating normally.
http://space.com/images/040429_cassini_saturn_02.jpg
Saturn and its rings fill the full frame of the camera in this Cassini image taken March 27, 2004 as the craft is just weeks from going into orbit.
Gio, ti sei svegliato adesso? :D
Quando vedo tra le email di notifica una fila di thread che iniziano con [Space] so che ti sei collegato... :asd:
Originariamente inviato da gpc
Gio, ti sei svegliato adesso? :D
Quando vedo tra le email di notifica una fila di thread che iniziano con [Space] so che ti sei collegato... :asd:
:asd:
no beh, un pò di tempo fa... e che ho anche altro da fare... :p
Rocket firing on tap for Cassini spacecraft
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: May 27, 2004
For the first time in nearly five years, the Cassini spacecraft's main engine system will fire up this evening for a critical course adjustment that will serve as a dress rehearsal of sorts for Saturn orbit insertion July 1.
http://spaceflightnow.com/cassini/images/040527cassini.jpg
An artist's concept of Cassini. Credit: NASA/JPL
The computer-initiated rocket firing, known as trajectory correction maneuver 20, is scheduled to begin at 7:47:31 p.m. EDT and last some five minutes and 56 seconds. Changing Cassini's velocity by about 78 mph, TCM-20 will set up a flyby of the moon Phoebe June 11 and help set the stage for the 96-minute-long July 1 rocket firing required to put the spacecraft in orbit around Saturn.
TCM-20 is relatively minor as such things go, but it marks the first time the craft's propulsion system will have been fully exercised since a major 87-minute "deep space maneuver" in December 1998.
No one at NASA's Jet Propulsion Laboratory in Pasadena, Calif., expects any problems and a six-minute burn by the 100-pound-thrust main engine is "pretty small by SOI or DSM standards," said Cassini propulsion engineer Todd Barber, a veteran of the Galileo and Mars Exploration Rover missions. "That's the bad news. The good news is it's totally regulated, so we'll be able to verify that all the valves work and that the helium's flowing properly."
Helium provides the pressure needed to push propellant and oxidizer into the engine's combustion chamber. Cassini's main helium regulator began leaking shortly after launch in 1997, but by using a downstream valve to isolate the system between firings, engineers are able to manage the leakage. Those same procedures will be used for TCM-20, Saturn orbit insertion and a final major orbit adjustment burn in late August.
Unlike the lengthy, make-or-break SOI burn, TCM-20 could be carried out in "blow-down" mode using residual tank pressure, Barber said, which wouldn't require use of the helium regulator.
"But it's ostensibly there not only to target Phoebe for our June 11 flyby, the major purpose of this burn is a propulsion system checkout," he said. "It gives us a real warm fuzzy going into SOI."
It currently takes radio signals from Earth, traveling through space at 186,000 miles per second, more than one hour and 20 minutes to reach Cassini. As a result, tonight's rocket firing, like all such burns, will be initiated, controlled and shut down by the spacecraft's on-board computer.
The burn "is a good practice run, no question about that," said Cassini project manager Bob Mitchell. "But the science from this is kind of a big deal, too."
Discovered in 1898, Phoebe measures just 137 miles across, orbits Saturn at a distance of nine million miles and circles the planet in the opposite direction from its other moons. Because of that, and the tilt of its orbit, scientists believe Phoebe may be a captured asteroid or a Kuiper belt object left over from the birth of the solar system.
Tonight's rocket firing will allow Cassini to pass within just 1,250 miles of the enigmatic moon.
"Voyager imaged Phoebe a long time ago and got some images that were quite distant, quite blurred and didn't really provide a whole lot of information," Mitchell said. "And now, we're going to get down to, I think, something like 18-meters-per-pixel resolution. And Phoebe has enough gravity that while it really doesn't do anything of any significance to the trajectory, it does tweak it enough that you can feel it.
"So the radio science guys ... will get a mass estimate from the flyby. From that and images that tell you the size, they get the density. So there's quite a bit of science coming back from this."
Cassini was launched Oct. 15, 1997, from the Cape Canaveral Air Force Station. Using two gravity assist flybys of Venus, one of Earth and a final boost from Jupiter, Cassini has taken seven years to reach its target. Carrying 12 sophisticated instruments and a European probe with a half-dozen instruments of its own that will descend through the atmosphere of the moon Titan, the $3.4 billion Cassini is the most complex deep space mission ever attempted.
The 96.4-minute Saturn orbit insertion rocket firing, which will change Cassini's velocity by slightly more than 1,400 mph, is scheduled to begin at 10:35:42 p.m. EDT on June 30. It should end around 12:11 a.m. July 1, kicking off a planned four-year orbital tour of the ringed planet and its many moons.
fdA40-99
28-05-2004, 00:13
Per chi volesse saperne di più su Saturno allego una "semplice" bibliografia: ovviamente da guardare le opere di Cassini e di Huygens. Poi Kant (Teoria del cielo), Herschel, Laplace, Loki e storia dell'astronomia di Cambridge.
Il sito della missione, invece, è http://saturn.jpl.nasa.gov nel caso non fosse stato linkato prima... ;)
si, è già stato postato... cmq è sempre bene ricordiarlo. Questo è quello dell'ESA:
http://www.esa.int/esaSC/120378_index_0_m.html
Cassini-Huygens approaching Saturn and Titan
26 May 2004
ESA PR 28-2004. Launched in October 1997, the ESA/NASA Cassini-Huygens mission is currently heading for Saturn. While ESA’s Huygens probe will be the first ever to land on the surface of a moon in the outer Solar System, NASA’s Cassini orbiter will continue to explore Saturn and its rings.
After an almost seven-year journey and four gravity-assist swing-by manoeuvres the spacecraft will be inserted into its orbit around Saturn on 30 June (Pacific Daylight Time, 1 July CET) and reach its closest approach to Saturn. The Huygens probe will be detached from its mother ship on 25 December and land on Titan in January next year.
On 3 June a press conference will take place at NASA Headquarters, Washington, with ESA participation, to present the mission and outline milestones and upcoming media activities.
Media representatives can follow this press conference from ESA/ESOC, where several project representatives will be present, together with David Southwood, ESA Director of Science, or from one of the other ESA establishments. They are requested to complete the attached reply form and fax it to the Communication office at the establishment of their choice.
The ESA TV service will also broadcast the press conference via Eutelsat W1. Further information concerning the retransmission schedule can be found on http://television.esa.int.
Originariamente inviato da GioFX
Note:
La dimensione e l'obiettivo di Cassini-Huygens (Saturno-Titano) ha richiesto l'uso del più potente lanciatore espandibile al mondo, il Titan IV/Centaur, ma questo non basta a lanciare direttamente la navetta verso la sua destinazione, è stata quindi studiata una traiettoria unica nel suo genere che ha previsto lo sfruttamento della forza gravitazionale di Venere (2 passaggi, 1998-99) e della Terra (2001).
Cassini usa come le precedenti sonde interplanetarie e navette Apollo, Viking, Pioneer e Voyager o le attuali Galileo e Ulysses, un generatore termoelettrico a radioisotopi (RTG) per produrre energia elettrica necessaria a missioni lunghe parecchi anni.
Un RTG non è un reattore nucleare, e non sfrutta nè processi di fissione nè di fusione nucleare, bensì genera calore con la naturale decadenza radioattiva dell'isotopo plutonio-238 (non adatto ad uso militare). Il calore così prodotto è convertito in elettricità da convertitori termoelettrici a stato solido.
http://saturn.jpl.nasa.gov/spacecraft/images/rtgcutout.jpg
Sei sicuro che no sia stato progettato da Nabrez? :sofico: :mc:
Originariamente inviato da david-1
Sei sicuro che no sia stato progettato da Nabrez? :sofico: :mc:
no, Nabrez l'avrebbe fatto a legna... :D
Originariamente inviato da GioFX
no, Nabrez l'avrebbe fatto a legna... :D
:rotfl:
Comunque...
C'è anche questo:
http://ciclops.lpl.arizona.edu/index.php
che è il sito dove sono raccolte le foto della missione.
Bellissime anche quelle di Giove, me le sono appena scaricate...
Originariamente inviato da gpc
:rotfl:
Comunque...
C'è anche questo:
http://ciclops.lpl.arizona.edu/index.php
che è il sito dove sono raccolte le foto della missione.
Bellissime anche quelle di Giove, me le sono appena scaricate...
ottimo, tutti questi link dopo li metto in prima pagina. :)
Cassini getting ever closer to colorful Saturn
CICLOPS/SPACE SCIENCE NEWS RELEASE
Posted: June 3, 2004
As Cassini coasts into the final month of its nearly seven-year trek, the serene majesty of its destination looms ahead. The spacecraft's cameras are functioning beautifully and continue to return stunning views from Cassini's position, 1.2 billion kilometers (750 million miles) from Earth and now 15.7 million kilometers (9.8 million miles) from Saturn.
http://spaceflightnow.com/cassini/images/040603saturncolor.jpg
Credit: NASA/JPL/Space Science Institute
In this narrow angle camera image from May 21, 2004, the ringed planet displays subtle, multi-hued atmospheric bands, colored by yet undetermined compounds. Cassini mission scientists hope to determine the exact composition of this material.
This image also offers a preview of the detailed survey Cassini will conduct on the planet's dazzling rings. Slight differences in color denote both differences in ring particle composition and light scattering properties.
Images taken through blue, green and red filters were combined to create this natural color view. The image scale is 132 kilometers (82 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colorado.
jumpermax
15-06-2004, 01:29
Primo incontro venerdì con Phoebe... guardate quanto è carina... (non fate caso ai brufoli :D )
http://saturn.jpl.nasa.gov/multimedia/images/small-moons/images/PIA06064.jpg
http://saturn.jpl.nasa.gov/cgibin/gs2.cgi?path=../multimedia/images/small-moons/images/PIA06064.jpg&type=image
The Face of Phoebe
June 13, 2004 Full-Res: PIA06064
Phoebe's true nature is revealed in startling clarity in this mosaic of two images taken during Cassini's flyby on June 11, 2004. The image shows evidence for the emerging view that Phoebe may be an ice-rich body coated with a thin layer of dark material. Small bright craters in the image are probably fairly young features. This phenomenon has been observed on other icy satellites, such as Ganymede at Jupiter. When impactors slammed into the surface of Phoebe, the collisions excavated fresh, bright material -- probably ice -- underlying the surface layer. Further evidence for this can be seen on some crater walls where the darker material appears to have slid downwards, exposing more light-colored material. Some areas of the image that are particularly bright - especially near lower right - are over-exposed.
An accurate determination of Phoebe's density - a forthcoming result from the flyby - will help Cassini mission scientists understand how much of the little moon is comprised of ices.
This spectacular view was obtained at a phase, or Sun-Phoebe-spacecraft, angle of 84 degrees, and from a distance of approximately 32,500 kilometers (20,200 miles). The image scale is approximately 190 meters (624 feet) per pixel. No enhancement was performed on this image.
ragazzi manca poco a Saturno....
[/QUOTE]
Closest Ever Images of Saturn's Moon Phoebe Captured By Cassini
By Robert Roy Britt
Senior Science Writer
posted: 09:24 am ET
13 June 2004
NASA's Cassini spacecraft successfully completed its first close flyby of a moon of Saturn Friday, officials announced Saturday. Detailed images revealed a heavily cratered surface that has astronomers debating the tiny satellite's origins.
The most detailed image released so far shows a tiny world riddled with ancient pockmarks, but with great variations of surface brightness. Phoebe in general is very dark, but close inspection revealed areas so bright they're washed out in the picture.
"What spectacular images," Carolyn Porco, Cassini Imaging Team leader at the Space Science Institute in Boulder, Colorado, said in a statement. "So sharp and clear and showing a great many geological features, large and small. It's obvious a lot of new insights into the origin of this strange body will come as a result of all this."
Phoebe is about 137 miles (220 kilometers) wide, or roughly one-fifteenth the diameter of Earth's Moon.
Phoebe orbits Saturn backward compared to the planet's rotation. That plus its dark surface has long had scientists speculating that it might be an object captured from the Kuiper Belt, a region of icy bodies beyond Neptune.
Though it is too early to say, researchers believe closer inspection of the pictures of Phoebe could reveal this to be the case, and could also tell them more about the early solar system.
"Phoebe is a heavily cratered body," said Torrence Johnson, Cassini imaging team member at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We might be seeing one of the chunks from the formation of the solar system, 4.5 billion years ago. It's too soon to say."
The highest resolution image so far released shows a crater near the right hand edge with bright rays that extend from its center. This suggests that dark material coats the outside of what may be a predominantly icy body, scientists said. Kuiper Belt Objects, more so than asteroids, are thought to be made up largely of ice.
The large craters has also led to speculation that Phoebe, the largest of Saturn's outer moons, might be the parent of the other, much smaller backward-orbiting outer moons of Saturn.
"Looking at those big 50 kilometers (31 mile) craters, one has to wonder whether their impact ejecta might be the other tiny moons that orbit Saturn on paths much like Phoebe's," said Joseph Burns, an imaging team member and professor at Cornell University.
Craters on Phoebe are thought to be the result of collisions with smaller objects, some perhaps up to 328 feet (100 meters) wide.
During Cassini's planned four-year tour it will orbit Saturn 76 times and execute 52 close encounters with seven of Saturn's 31 known moons. It may discover other moons not yet spotted within Saturn's ring system. But this will be the last close look at Phoebe during the mission.
Cassini came within about 1,285 miles (2,068 kilometers) of the dark moon. The spacecraft imaged Phoebe and took radar and other readings. Several hours later it turned to point its antenna to Earth and send pictures and data back.
Cassini sped by the moon at a relative speed of 13,900 mph (20,900 kilometers per hour) relative to Saturn.
The last visit to Phoebe was with Voyager 2 in 1981. That flyby was 1,000 times farther from the moon, however.
http://space.com/images/h_phoebe_crater_cu_0611_02.jpg
This eye-popping high-resolution image of Phoebe's pitted surface taken very near closest approach shows a 13-kilometer (8-mile) diameter crater with a debris-covered floor. Part of another crater of similar size is visible at left, as is part of a larger crater at top and many scattered smaller craters. Credit: NASA/JPL/Space Science Institute
http://space.com/images/h_phoebe_crater_0611_02.jpg
This image was obtained on June, 11 2004 at a phase, or Sun-Phoebe-spacecraft, angle of 79 degrees, and from a distance of 8,314 miles (13,377 kilometers ). The image scale is approximately 263 feet (80 meters) per pixel. No enhancement was performed on this image. Credit: NASA/JPL/Space Science Institute
http://space.com/images/h_cassini_phoebe_0612_02.jpg
First images from the Cassini flyby of Phoebe reveal it to be a scarred, cratered outpost with a very old surface and a mysterious past, and a great deal of variation in surface brightness across its surface. Credit: NASA/JPL/Space Science Institute
Originariamente inviato da jumpermax
questa missione se ha successo potrebbe quasi oscurare quella su Marte... chissà che paesaggio ci troveremo davanti su Titano? L'aspetto di marte in fin dei conti ci era noto... di Titano abbiamo solo le foto del voyager...
fino a quando svilupperanno la PNN ci si deve accontentare, però questa missione mi piace!
Titano dicono abbia OCEANI di metano liquido ed io mi domando:
ma se sta povera sonda capita proprio sopra uno di questi oceani? affonda ed è gia persa, ...............giusto?
Originariamente inviato da Thell
ma se sta povera sonda capita proprio sopra uno di questi oceani? affonda ed è gia persa, ...............giusto?
Si, anche se molti suoi strumenti possono resistere per qualche secondo/minuto.
Originariamente inviato da GioFX
Si, anche se molti suoi strumenti possono resistere per qualche secondo/minuto.
ma da sott'acqua.......ehm...da sottometano come trasmette? :eek:
Originariamente inviato da Thell
ma da sott'acqua.......ehm...da sottometano come trasmette? :eek:
non è detto che affondi subito... :p
e cmq in bassa frequenza riesci a trasmettere anche in un mare di cacca... :D
Originariamente inviato da GioFX
non è detto che affondi subito... :p
e cmq in bassa frequenza riesci a trasmettere anche in un mare di cacca... :D
e che ci mettono? la ciambella con la paperella? :D
a bassa frequenza i filmini e le foto non ce le manda però :(
non possono usare la correlazione quantistica come nell'università di zurigo?
Veramente ci contano che cada in un oceano, tant'è che è progettata per galleggiare e studiare il modo di eventuali onde.
Anzi, se cade in un oceano è meglio, perchè così sono sicuri che l'antenna risulta puntata verso l'alto.
Cassini mission hinges on Wednesday's engine firing
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 29, 2004
After a seven-year voyage from Earth, NASA's $3.3 billion Cassini probe is racing toward a make-or-break rocket firing Wednesday, a 96-minute maneuver designed to put the craft in orbit around the ringed planet Saturn for a four-year scientific odyssey.
Flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., sent final commands to Cassini over the weekend, setting the stage for main engine ignition at 10:35:42 p.m. Wednesday.
http://www.spaceflightnow.com/cassini/images/040612soi.jpg
Cassini fires its engine to enter orbit around Saturn as illustrated in this artist's concept. Credit: NASA/JPL
Operating more than 930 million miles from Earth - so far it takes radio signals an hour and 23 minutes to make a one-way trip - Cassini's on-board computer system must carry out the all-important rocket firing on its own.
At this point, flight controllers can only sit and wait. And chew their nails.
"I think about the Cassini mission as having three primary segments and then two rather hair-graying events that connect those segments into one continuous mission," said project manager Bob Mitchell. "The segments are designing and building the spacecraft, flying the spacecraft to Saturn and then conducting the science mission at Saturn.
"And the hair graying events are launch and orbit insertion, which is coming up tomorrow. Now for the launch event, I think we've all recovered from that very nicely, primarily because it was just so outstandingly successful. ... We're about to go through our second hair-graying event."
At a news conference today, he told reporters "I think I can speak for all the team members when I say that while we're all at least a little bit nervous, we're also very excited. It's an event we welcome very much and are pleased to have here."
The goal of the Cassini mission is to study Saturn's windy atmosphere, its complex ring system, several of its icy moons and how the planet's magnetic field interacts with the space environment. In what promises to be one of the most exciting phases of the mission, a European-built probe called Huygens will be released from Cassini on Christmas Eve for a parachute descent into the thick nitrogen atmosphere of Saturn's moon, Titan, on Jan. 14.
In all, Cassini is expected to complete 77 orbits of Saturn over the next four years, requiring 157 trajectory-nudging rocket firings. The gravity of Titan will be used for major course changes, with 45 planned flybys. Seven close flybys of smaller, icy moons also are planned.
But first, Cassini must execute the Saturn Orbit Insertion maneuver, or SOI.
http://www.spaceflightnow.com/cassini/images/040612arrival.jpg
This graphic shows the ring plane crossing and orbit insertion burn. Credit: NASA/JPL
To achieve orbit around Saturn, the 12,600-pound Cassini must reduce its velocity by about 1,400 mph using a rocket engine that only produces 100 pounds of push. As a result, the engine must fire for 96.4 minutes to put Cassini into the desired orbit.
If the engine shuts down early, the computer will switch to a spare. But the end result must be roughly the same - 96 minutes of braking - or Cassini might not be able to achieve its long-awaited mission.
"There are no problems, we have no indication of any problems with the spacecraft that would have any adverse effect on SOI," Mitchell said. Added Julie Webster, lead spacecraft engineer: "This spacecraft, this whole mission has been an incredibly smooth one to fly."
"This orbit insertion sequence is self contained on the spacecraft," she said. "We loaded up the last command we're going to send to it late Saturday night, Sunday morning, and we've just been clocking it out ever since and getting no indications of anything. We expect this to go very, very smoothly."
The propulsion system has worked flawlessly since Cassini's launch aboard a Titan 4B rocket on Oct. 15, 1997. The only issue of any consequence was a leaking helium regulator that forced engineers to change the way they pressurize the system for major rocket firing.
Helium is used to push propellants through Cassini's plumbing and into the main engine's combustion chamber at a constant pressure. The regulator controls that pressurization, which is needed for long firings like the upcoming Saturn Orbit Insertion burn.
In this case, Cassini's complexity and built-in redundancy came to the rescue. By delaying the opening of a downstream latch valve to just 70 seconds or so before main engine ignition, engineers were able to work around the regulator issue with no impact to mission operations. The procedure was used for a major 88-minute Deep Space Maneuver rocket firing back in 1998 and again in late May for a six-minute burn that set up a flyby of the moon Phoebe.
"We've got a real nice propulsion system," lead propulsion engineer Todd Barber said in an earlier interview. "It's a plumber's nightmare, there are so many valves and alternate paths and contingency paths available that basically, we're able to handle a lot of anomalies. And the regulator leak we saw was right after launch and we've been able to accommodate that with the way we time the opening of valves, etc."
Even so, Barber will feel much better after Cassini successfully brakes into orbit. "It's been a long time coming and the hopes and dreams of thousands of engineers are resting on that one evening. When we get the signal back is when we'll all go take a deep breath. Hold your ears, because they might pop."
http://www.spaceflightnow.com/cassini/images/040612enginenozzles.jpg
Cassini's two engines are seen in this pre-launch photo. Credit: NASA/JPL
Cassini is equipped with two rocket engine assemblies, REA-A and REA-B. Rocket Engine Assembly B, however, is strictly a backup. It has never been fired.
Mitchell said in an interview he had high confidence the SOI maneuver will work normally and that REA-B will not be needed "based on all of the testing, all the elaborate work that we have put into this, as well as our experience with the spacecraft to date. We've done 15 or 16 maneuvers using the main engine ... and so we have every reason to believe this thing is going to work just fine."
But, he added, "the software the thing flies is all complex and I just worry about what bugs are still in there. I think it must be inevitable that there are still bugs in there for something this complex. We've tested it extensively, we have a test bed here in the basement of our building that is a quite high fidelity spacecraft simulator and the sequences have been run through there many, many times. We have injected faults, we've had various components break, where we simulated a break in the test bed and looked to see what response we got. And at the moment, everything works. All the tests that we've done, all the simulations indicate that everything is just fine."
The maneuver has little margin for error. Cassini first must avoid any crippling debris impacts when it crosses the ring plane between the F and G rings, moving from the lower side of the rings to the upper side as viewed from Earth.
Pioneers 10 and 11, along with Voyager 2, flew through the gap with no problems but Cassini flight planners are taking no chances. Before traversing the ring plane, the spacecraft will be oriented with its high-gain dish antenna facing the direction of travel to act as a shield.
Voyager 2 went through outer edge of the G ring and its instruments recorded "lots of evidence of micrometeoroid hits when going through, but nothing serious," said Voyager veteran Torrence Johnson, a Cassini imaging team member and chief scientist for the Galileo mission.
"So we have that maneuvering to do and then there's the fact that the place is just a junky system," he said in an interview. "We're going in close, we're skimming right over the rings, everybody thinks we've modeled all this right and we're being reasonably cautious. But I told some of the guys early on, if they're going to be scared of ring particles they ought to remember John Paul Jones' letter to Congress, 'give me a fast ship for I intend to sail in harm's way.'
"I don't think anybody's real complacent about this thing," Johnson said. "I think we've done everything we can to make sure we don't have any human or systems screw ups, but nature can still get you."
Jerry Jones, Cassini's chief navigator, said flying through the ring plane relatively close to Saturn will save propellant and makes the rocket firing more efficient. "But the real clincher, given all that, is the science in that close. We're going to be sitting there looking right down on those rings."
"We've got one class-A camera on this spacecraft," he said in an interview. "It's a beautiful telescope, it has great resolution, very sharp edges and for optical navigation, I'm just pleased as punch. ... The science opportunity going over the rings should be just fantastic, to say nothing of showing the public what they've paid for."
http://www.spaceflightnow.com/cassini/images/040612soiplanet.jpg
This graphic shows Cassini's track as it enters orbit around Saturn. Credit: NASA/JPL
Once safely through the ring plane, Cassini will re-orient itself once again, swapping ends to put the main engine forward for the SOI burn. NASA originally planned to carry out the rocket firing "in the blind," with Cassini focusing on science observations while the engine put on the brakes. But in the wake of back-to-back Mars mission failures in 1999, NASA management ordered engineers to figure out a way for Cassini to provide at least some information about the start of the burn, its progress and its termination.
"So we went back and scrambled then," Barber said. "We had a compromise solution. We could have pointed the high-gain antenna to Earth during the whole burn and have telemetry but there was a large delta V (fuel) penalty to do so. So the plan is to switch to a low gain antenna and that will allow us to maintain Doppler during the burn."
While no actual data will be transmitted to Earth, analysis of the Doppler shift of a carrier signal from the spacecraft will tell engineers when the burn started, the precise deceleration it produces and when it stops.
"There were two key things we wanted to be sure we could differentiate between," Mitchell said. "One was in the event we just lost it entirely and never saw it again, we wanted to be able to differentiate between whether we had a problem going through the ring plane or whether we did that successfully and had a problem during the course of the burn itself. So with the data we have, we will know that quite well."
After re-orienting itself for SOI, Cassini will begin transmitting a carrier signal. Six minutes later, the burn will begin, showing up on computer screens at the Jet Propulsion Laboratory as a change in the slope of the carrier frequency. Thirty minutes later, the signal is expected to fade out for 25 minutes or so as Cassini passes behind Saturn's A ring as viewed from Earth.
Engineers then expect six minutes of carrier through a gap in the rings known as the Cassini division before another 28-minute communications blackout while the spacecraft passes behind the broad B ring. Closest approach to Saturn - 12,400 miles from the planet's cloud tops - is expected at 12:03 a.m. July 1, nine minutes before the SOI burn comes to an end. The first images and other data from the orbit insertion maneuver are expected around 8:39 a.m.
"We turn off of Earth line shortly prior to the ring plane crossing," Mitchell explained. "We turn to point the high-gain antenna in the direction we need to be in to shield the rest of the spacecraft and then there's a period of about an hour where we don't have any contact.
"Then when we turn back to go to the burn attitude, at about the time we get to that attitude, which is six minutes prior to the burn start, we will crank up a signal that comes from one of the low gain antennas. There's no telemetry, it's just a carrier.
"But that carrier will allow us to get Doppler and that'll tell us if the spacecraft is operating fine and has not had any safing events. And then during the course of the burn, that Doppler will let us see quite accurately what the acceleration levels are. So if the system is performing nominally or over performing or under performing, the Doppler will show that very well."
The day after orbit insertion, Cassini will pass within 205,000 miles of Titan, the first official Titan encounter of the mission. Between July 4 and 11, the spacecraft will be out of contact as Saturn passes behind the sun as viewed from Earth. The SOI sequence will end on July 30 as tour sequence No. 3 begins.
Sometime around Aug. 23, Cassini's main engine is scheduled to fire in what will be the last fully helium-regulated burn of the mission: a 51-minute maneuver that will change the spacecraft's velocity by 877 mph. The Perigee Raise Maneuver, or PRM, will raise the low point of Cassini's orbit and set up the first close flyby of Titan in October. After another flyby in December, the Huygens probe will be released for atmospheric entry during the mission's third Titan encounter in January.
The SOI maneuver is one of only three so-called "critical sequences" built into Cassini's mission software. A critical sequence is one that simply must execute properly to ensure mission success. The launch to Venus was one such sequence and the only other one is the Huygens data relay sequence.
SOI is "the only maneuver that we will do throughout the entire course of the mission where we just absolutely have to do this burn right now," Mitchell said at a news briefing. "If this burn doesn't work, then we would have a Saturn flyby and that's not what we're here about. So we have designed what we refer to as a critical sequence where no matter what fault might occur, the spacecraft will not let the burn halt. Now in some modes it will stop the burn, swap to the other engine and then continue on with the burn. But the burn will continue even in the presence of faults."
During normal operations, a problem with a spacecraft system would trigger fault-protection software that would shut down unnecessary activity, a condition known as safe mode. There are numerous variations, depending on the nature and timing of the fault and whether the spacecraft still knows its orientation in space. The end result, however, is the same: Cassini shuts down, finds the sun (Earth will never be more than six degrees away), switches to low-data-rate communications and awaits instructions from Earth.
Because of Saturn's great distance and the slow-speed radio link used in safe mode, engineers would need at least 48 hours to restore Cassini to normal operations. Such a fault during the SOI maneuver would shut the main engine down, interrupting the all-important rocket firing and possibly dooming the mission. But in critical sequence mode, that will not be allowed to happen.
"In critical mode, if the spacecraft detects a fault - we get a glint in the eye of the star scanner or the thrusters don't like what they're doing or a piece of hardware doesn't work right - the spacecraft will detect a fault," Webster said. "The sequence will halt and the spacecraft is allowed through its autonomous fault protection to go off and fix the fault.
"And then it will come back and say I've detected a fault, I've fixed the fault. And then it'll come back and say OK, critical sequence, you can restart. And the critical sequence will say Oh, but I've gotta remember where I was. We have what we call a mark and rollback strategy. So it'll roll back to the last good mark point and it will resend all the commands necessary to execute the next states that it needs to be in. It'll recommend all of those and continue on. And so, if there's a fault anytime during the critical sequence, it'll stop, halt, detect the fault, correct the fault and then restart the sequence."
That's where Cassini's second main engine comes in. If a fault of any kind interrupts the SOI sequence, the computer will fire up rocket engine assembly B and continue the burn.
"In the burn, we have already disabled any fault protection activity that's not necessary to complete the burn," Webster said. "So we've got fault monitors, say, on the CDS (command and data system) computer and on the radio. Well, the radio's not necessary to complete a burn. Neither is the CDS, ironically, because the attitude and articulation control system also has its own computer and once the CDS has told it to go do a burn, it takes over and says I don't need you anymore, I'll complete this burn and I'll let you know when I'm done. So only the fault protection that's necessary to complete the burn is active.
"It would detect a fault in where it's pointing or the propulsion system wasn't acting right, maybe under thrusting or over thrusting. If there's a fault during the burn, then we terminate the burn. We try to fix the fault and then we mark and roll back, pick up where we did, restart but we're going to restart on the second engine. It takes at least two hours to cool down one engine. So 10 minutes later, we can restart on engine B and minimize our overall cost."
But any safe mode that would necessitate firing REA-B also would terminate priceless SOI science operations, a small price to pay if survival of the mission is at stake. Cassini has a seven-hour window in which to complete the SOI maneuver and "as long as we got the correct amount of burn at any time in that seven-hour period, we would get into orbit," Webster said. "We might not like the orbit, but we'd get into orbit."
Cassini 'go' for Saturn orbit insertion burn
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 30, 2004
Executing stored instructions, the electronic brain of NASA's Cassini probe made final preparations for a critical 96-minute rocket firing tonight that will slow the craft by about 1,400 mph and allow Saturn's gravity to pull it into orbit.
The make-or-break Saturn Orbit Insertion - SOI - maneuver was scheduled to begin at 10:36 p.m. EDT and end around 12:12 a.m. Thursday. If successful, the burn will put Cassini in a long orbit around Saturn, kicking off a four-year tour of the ringed planet, its magnetosphere, its largest moon, Titan, and a retinue of smaller, icy satellites.
If the rocket firing fails or falls short of its 96-minute target duration, the $3.3 billion spacecraft will sail past Saturn and into a useless orbit around the sun.
"Unlike the two Voyagers that flew by Saturn in the early '80s and obtained just days worth of Saturn close-in science, Cassini-Huygens will be for Saturn what the Galileo mission was for Jupiter: a long-term science observatory," said Ed Weiler, NASA's associate administrator for space science.
But, he cautioned, "we are not there yet. Although things have gone very, very well so far, Saturn orbit injection will be the most critical event in the mission's life since launch. This main engine burn must be performed as planned or the mission will be lost.
"Unlike the Mars (rover) landings, where we had the 'six minutes from hell,' so to speak, in this case it'll be 96 minutes in purgatory. I hope the outcome will be as successful as our experiences with the Mars missions last January."
Engineers and managers at the Jet Propulsion Laboratory in Pasadena, Calif., believe it will. They said today the spacecraft has performed virtually flawlessly during the seven years it's taken Cassini to reach Saturn and they are confident it pull off the SOI burn, as Weiler said the most important single maneuver since launch from Earth on Oct. 15, 1997.
"Today, the Cassini spacecraft is in an excellent state of health and it is ready to perform the main engine burn tonight," said Julie Webster, lead vehicle engineer at JPL. "The spacecraft, the flight software and the on-board (computer command) sequences are now completely self contained and need no ground interaction from us to complete this burn. If a fault occurs on the spacecraft, the software will isolate the fault, identify the cause, fix it and continue on with the burn with no ground intervention."
The only issue of any significance is the possibility of high winds at a tracking station in Canberra, Australia. If the winds exceed about 47 mph, a 230-foot-wide dish antenna needed to pick up Cassini's radio signal will have to be stowed, delaying confirmation of a successful rocket firing.
"This has no bearing on the performance of the spacecraft," said Cassini program manager Bob Mitchell. "The spacecraft is perfectly capable of doing what it needs to do and weather on Earth is just not a factor.
"The thing that would be influenced is our blood pressure throughout the course of the evening," he joked. "However, a recent weather report from Canberra was favorable. It didn't eliminate the threat entirely, but it is favorable. So we don't believe it's going to be a problem."
Because of Cassini's enormous distance from Earth - some 934 million miles - radio signals from the spacecraft take an hour and 23 minutes to reach flight controllers at JPL. As a result, confirmation of events during SOI will be delayed by the same amount. In the timeline discussion below, "Earth-receive time," converted to Eastern Daylight Time, is used throughout.
"After 6.7 years we're at Saturn," said lead navigator, Jeremy Jones. "We're feeling the gravity well, falling into Saturn quite rapidly. ... This is the E-ticket ride, I'll tell you."
The numbers prove his point. At noon today, Cassini was 403,891 miles from Saturn and moving through space at 26,846 mph. By 6 p.m., the craft will be roughly half that far out - 233,014 miles - and its velocity will be up to 33,557 mph. Three hours later, the distance will be just 155,343 miles and its speed will be up to 42,506 mph.
The first critical milestone in the SOI sequence is the so-called ascending ring plane crossing. Approaching Saturn from below the plane of its rings, Cassini will cross that plane, in a broad gap between the F and G rings, at 10:11 p.m. That region is thought to be clear of any major pieces of ring debris, but no one knows for sure. At Cassini's velocity, an impact with anything larger than a very small pebble could cause major damage.
To be on the safe side, the spacecraft will re-orient itself an hour ahead of time, pointing its high-gain dish antenna in the direction of travel to act as a shield, cutting off telemetry from the spacecraft for the duration of the SOI maneuver. At the moment of ring plane crossing, Cassini will be just under 100,000 miles from Saturn - less than half the distance between the Earth and moon - and streaking through space at 50,335 mph.
"The antenna is a graphite-epoxy structure, so it's quite rugged and very capable of withstanding the kinds of small dust grains that we believe might be in this region," Mitchell said.
Once above the ring plane, Cassini will re-orient itself for the Saturn Orbit Insertion burn, pointing its main engine in the direction of travel. It also will begin transmitting a radio carrier signal using a low-gain antenna. The signal will not carry any data. But by monitoring how its frequency changes due to the SOI rocket firing's effect on Cassini's velocity, engineers will be able to confirm the start of the burn and the engine's overall performance through engine cutoff.
The moment of truth arrives at 10:35:42 p.m. when Rocket Engine Assembly A - REA-A - flashes to life, pushing against Cassini's 53,691-mph forward motion with a mere 100 pounds of thrust. Over the course of 96.4 minutes, REA-A will consume 1,874 pounds of rocket fuel, roughly one third of the 6,600 pounds Cassini was launched with, slowing the spacecraft by 1,396 mph and ensuring Saturn's gravity pulls it into the desired orbit.
Thirty minutes into the burn, at 11:06 a.m., Cassini will move behind the A ring as viewed from Earth and the carrier signal may be lost for up to 25 minutes or so. The signal should show back up for six minutes when Cassini "sees" Earth through a gap in the rings known as the Cassini division. Then communications may be lost again for 28 minutes or so as the spacecraft moves behind the B ring.
Saturn closest approach, or periapsis, will occur 10 minutes before the end of the burn, at 12:03 a.m. By this point, Saturn's gravity will have boosted Cassini's velocity to 69,350 mph. But by the end of the burn at 12;12 a.m., the velocity will have dropped to 68,000 mph and Cassini will be safely in orbit.
Weather in Australia permitting, engineers at JPL should be able to confirm the start of the rocket firing monitor its performance between ring blackouts and confirm the end of the burn. A few minutes later, Cassini is programmed to turn back toward Earth and transmit 20 seconds of engineering data starting around 12:30 a.m. The craft then will re-orient itself yet again to aim its cameras at Saturn's rings for 75 minutes of up-close science observations.
It then will re-orient itself antenna forward for the descending ring plane crossing and then point back toward Earth to begin downlinking its treasure-trove of science data. The first pictures are expected Thursday morning.
"Once we're done with about a 75-minute data observation period, we turn again for the descending ring plane crossing, again point the high-gain antenna as a protective shield," Mitchell said. "Once that's complete, we're going to turn and look back up at the rings, now on the sunlit side, take another set of images, mostly around the outer extent of the visible part of the rings. We then turn back to Earth and play this data back over about an 18, 19-hour period of time."
While confident, Mitchell cautioned "this thing is not a slam dunk by any means."
"There are two general concerns," he said. "One is the environment, primarily the environment of the rings. We have studied this very carefully, we believe we've taken prudent actions, we believe we've got the safest possible course of action, but it's not a guarantee.
"And then for the spacecraft itself, the spacecraft isn't going to do anything tonight that it hasn't already done in flight. But a 96-miute burn, where all of the systems have to work right for this amount of time, is a concern. Our confidence in the spacecraft is high, we have no specific reason to be concerned, but this is not a assured, either."
In preparation for the rocket firing, Cassini's on-board software opened low-pressure helium latch valves Tuesday. A backup inertial reference gyroscope was turned on and warmed up for use as needed during the burn. This morning, the main engine gimbal system was activated so the engine nozzle can be pre-positioned and the spacecraft's accelerometer was calibrated.
In short, Webster said, all systems were "go" for SOI.
"If the burn goes fine and we just don't get the signal back on the ground for any reason, we will get about 20 seconds of the high-gain coming in right before we turn go off and do the images," Webster said. "So if everything's perfect through the burn, we should get that little 20-second blip. That's very good because that tells us that the spacecraft didn't do any safing event or didn't stop the burn for any reason because the background sequences are still going. That's the good indication. That'll come in about 12:30 a.m. (EDT)
"I'm an old telecom person, so I actually wouldn't be concerned about this until past 3 a.m. ... I would not get any panic level until 6 or 7 in the morning. That's not unusual in low gain safing to have a little bit of trouble, especially with the Doppler changes that are going on with the spacecraft. Sometimes it just takes a while to find the signal. But I have full faith in this spacecraft, that it's going to make this burn one way or the other."
von Clausewitz
01-07-2004, 00:42
Originariamente inviato da gpc
Veramente ci contano che cada in un oceano, tant'è che è progettata per galleggiare e studiare il modo di eventuali onde.
Anzi, se cade in un oceano è meglio, perchè così sono sicuri che l'antenna risulta puntata verso l'alto.
veramente si parla di possibile distese di metano allo stato liquido, per parlare di oceani bisognerà riscontrare l'esatta estensione sulla superficie di titano
cmq questa si che è una missione veramente interessante che ci potrà dare se non proprio risposte,almeno ulteriori elementi per capire l'origine e la formazione del sistema solare
Frank1962
01-07-2004, 08:42
Originariamente inviato da GioFX
Closing In: Saturn Fills Cassini Craft's Viewfinder
http://space.com/images/040429_cassini_saturn_02.jpg
Saturn and its rings fill the full frame of the camera in this Cassini image taken March 27, 2004 as the craft is just weeks from going into orbit.
ma come mai in questa foto l'ombra del pianeta che si riflette suglia anelli è cosi netta?
Originariamente inviato da Frank1962
ma come mai in questa foto l'ombra del pianeta che si riflette suglia anelli è cosi netta?
Perchè? Come dovrebbe essere?
Originariamente inviato da gpc
Perchè? Come dovrebbe essere?
e' telmente perfetto che sembra fatto al pc ;)
Cassini successfully arrives at Saturn
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 1, 2004; Updated at 2:10 a.m. EDT
NASA's $3.3 billion Cassini probe completed a seven-year, 2.2-billion mile voyage tonight, firing its main engine for a nerve-wracking 96 minutes to successfully brake into orbit around the ringed planet Saturn.
http://www.spaceflightnow.com/cassini/images/040612cassiniorbit.jpg
Credit: ESA
Throughout the all-or-nothing rocket firing, flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., could only sit and wait, monitoring events that had already taken place 934 million miles away.
At that distance, radio signals, moving at 186,000 miles per second, needed an hour and 24 minutes to complete a one-way trip between Saturn and Earth. As a result, Cassini's on-board computer was responsible for carrying out the most critical maneuver since launch Oct. 15, 1997, a maneuver that simply had to work or the mission would end in failure.
To everyone's relief, Cassini's main engine fired up on time at 10:36 p.m. EDT and shut down at 12:12 a.m., putting the craft in its planned initial orbit around Saturn.
"Flight, telecom," the Cassini communications officer called out. "The Doppler has flattened out."
Translation: Cassini's engine had shut down and Cassini was in orbit. Flight controllers burst into cheers, sharing hugs and high fives as Cassini lived up to its reputation for near flawless operation.
"It feels awfully good to be in orbit around the lord of the rings," said Charles Elachi, director of the Jet Propulsion Laboratory. "It's going to be a huge leap in our understanding of the Saturnian system."
Ed Weiler, NASA's associate administrator for space science, described the rocket firing as 96 minutes of purgatory during a news briefing Wednesday. Halfway through the burn, "I started to think gee, here we are sitting on this little pale blue dot, third rock from the sun. We just landed on Mars twice. We flew by a comet and picked up some comet dust (with the Stardust mission) and all within six months, we're about to go into orbit around a planet a billion miles away. How do we get away with having so much fun?
"This has just been an incredible ride," he said. "This wasn't NASA going into orbit around Saturn, it's the Earth going into orbit around Saturn because 17 countries made this happen. This is the way exploration should be done: by the Earth."
David Southwood, director of science for the European Space Agency agreed Cassini is a "world mission."
"But this evening I have to say, it's been the Americans' evening," he said. "This was America doing it right. ... There are Europeans involved in just about everything in the instrumentation, the science on Cassini and Huygens. It really is a mission where everybody is working together.
"But this evening, you guys did it right," he said. "Thank you JPL, thank you USA, thank you NASA."
Referring to ESA's Huygens probe, which will make a parachute descent into the atmosphere of Saturn's moon Titan in January, Southwood said the Saturn Orbit Insertion rocket firing would be a tough act to follow and "we have now to get it right, too."
"You really showed us how it's done. It was a very professional show and frighteningly on the nail. We've got a lot to live up to. Thank you everybody. It's been a great eveing."
The most sophisticated - and expensive - robotic spacecraft ever built, Cassini approached Saturn from below the plane of its rings. Using its high-gain antenna as a shield, the spacecraft sailed through the ring plane at 10:11 p.m., passing through a broad gap between Saturn's F and G rings. The region was thought to be empty of any debris larger than dust grains, but at Cassini's enormous approach velocity - more than 53,000 mph at that point - impacts posed a major concern.
But right on schedule, after Cassini re-oriented itself for the Saturn Orbit Insertion rocket firing, ground stations in Australia and California picked up Cassini's radio carrier signal at 10:27 p.m. EDT, confirming the spacecraft had survived the ascending ring plane crossing.
"One hurdle down, one to go," said Todd Barber, lead propulsion officer. "We're approaching two minutes before the SOI burn. The hopes and dreams of thousands of scientists and engineers are resting on the next few moments. So Godspeed, Cassini-Huygens. May we see you in orbit."
And with that, the moment of truth was finally at hand.
As timers counted down to the start of the Saturn Orbit Insertion rocket firing, engineers at JPL monitored computer screens showing a graphical representation of the carrier signal from Cassini. They were looking for a very precise, predicted change in the frequency of the signal due to the effects of the rocket firing, much like a siren changes pitch as a police car races past.
And right on schedule, at 10:36 p.m., the signal changed exactly as predicted. On computer screens, a horizontal line representing the carrier frequency suddenly bent sharply downward, matching the slope predicted for a normal rocket firing. Flight controllers burst into applause, relieved to know Rocket Engine Assembly A had fired on time to begin slowing Cassini's ever-increasing velocity.
Producing just 100 pounds of push against the enormous 54,000-mph velocity of the 9,970-pound Cassini, the main engine had to fire 96.4 minutes to produce the required deceleration and to ensure Saturn's gravity could capture the spacecraft and warp its trajectory into the planned orbit.
Thirty minutes into the burn, at 11:06 p.m., Cassini moved behind Saturn's A ring as viewed from Earth, dimming the carrier signal for about 25 minutes. After fading in and out as it was blocked by ring debris, relatively clear reception was established at 10:31 p.m. when Cassini had a brief, clear view of Earth again through a gap in the rings known as the Cassini division. Six minutes later, exactly as predicted, communications dropped out again for 28 minutes or so as the spacecraft moved behind the thicker B ring.
Still picking up speed from Saturn's gravitational attraction, Cassini reached periapsis, the closest it will ever be to Saturn - 12,400 miles from the cloud tops - at 12:03 a.m., just nine minutes before the end of the SOI burn. By that point, Saturn's gravity had boosted Cassini's velocity to a blistering 69,350 mph, four times faster than a space shuttle in Earth orbit and 32 times faster than the bullet from an assault rifle.
Waiting for the carrier signal to reappear from behind the B ring, Barber provided an impromptu Saturn weather report, predicting temperatures of "minus 226 degrees Fahrenheit, winds of 1,100 miles per hour or so, pressure highly variable depending on where you are in the atmosphere. At the top of the atmosphere, better than the best vacuum on Earth. Down in the depths, millions of atmospheres of pressure. Chance of helium rain inside the interior: 100 percent. Hurricanes the size of the Earth."
By the end of the SOI burn at 12:12 a.m., the velocity had dropped to around 68,000 mph as Cassini streaked away from the planet after close approach. While most reporters (including this writer) were not aware of it, navigators changed their prediction for the burn duration Wednesday, expecting 97 minutes instead of 96. Analysis of the carrier signal's frequency showed the rocket engine actually generated about 1 percent more thrust than expected. Cassini's flight computer compensated by shutting the engine down one minute early to achieve the planned deceleration of 1,400 mph. That translated into a 96-minute burn as originally expected.
With the conclusion of the SOI rocket firing, Cassini was finally in its planned initial orbit around Saturn. Over the next four years, the spacecraft will study Saturn's windy atmosphere, its complex ring system, several of its icy moons and how the planet's magnetic field interacts with the space environment. In what promises to be one of the most exciting phases of the mission, a European-built probe called Huygens will be released from Cassini on Christmas Eve for a parachute descent into the thick nitrogen atmosphere of Saturn's moon, Titan, on Jan. 14.
In all, Cassini is expected to complete 77 orbits of Saturn over the next four years, requiring 157 trajectory-nudging rocket firings. The gravity of Titan will be used for major course changes, with 45 planned flybys. Seven close flybys of smaller, icy moons also are planned.
Safely in orbit, Cassini turned so that its high-gain antenna was aimed back toward Earth for a brief, 20-second burst of carrier signal at 12:30 a.m. That switch from the low-gain to the high-gain antenna confirmed the spacecraft was operating normally and had not suffered any "safing" events during the burn that could have shut down science operations during Saturn close approach.
"We've got it!" Barber reported as yet another round of cheers and applause burst out. After sending the brief call home, Cassini turned away to begin a 75-minute sequence of ring observations.
"I feel great!" said program manager Bob Mitchell. "It was kind of a nail biter throughout."
One hour and 46 minutes after the end of the SOI burn, Cassini was expected to turn once again, orienting itself so the high-gain antenna could act as a shield during a descending ring plane crossing. Once safely through the ring plane, Cassini was expected to begin transmitting science and engineering data back to Earth. The first pictures were expected around 8:40 a.m. Thursday.
On July 2, Cassini will make its first official flyby of Titan, passing the cloud-shrouded world at a distance of 205,000 miles.
Larger than Pluto and Mercury, Titan's thick nitrogen atmosphere is thought to mirror Earth's shortly after the planet's formation. Based on approach photos, Cassini's cameras should be able to "see" the surface through specific spectral "windows." But just how well the cameras will be able to image the surface won't be known until after the Friday flyby.
Data playback from the Titan flyby is expected to begin around 6:15 p.m. Friday. If all goes well, a minor trajectory correction maneuver is scheduled Saturday at 8:30 p.m. to fine tune the orbit with a predicted velocity change of just 11 mph. Starting July 6, Cassini will be out of contact while Saturn passes behind the sun as viewed from Earth, completing the initial phase of Cassini's orbital mission.
In late August, a major rocket firing is planned to raise the low point of Cassini's orbit well beyond the rings and to set up the second Titan flyby Oct. 26. After another Titan flyby Dec. 13, the European Space Agency's Huygens probe will be released from Cassini on Christmas Eve for the three-week trip to Titan.
Huygens will slam into Titan's atmosphere on Jan. 14 for a two-and-a-half-hour parachute descent to the surface. Data from Huygens, including panoramic pictures of its enigmatic surface, will be beamed back to Earth through Cassini's radio system.
After that, Cassini will continue on its own, flying through a ballet of ever-changing orbits and beaming down up to four gigabytes of data per day.
GO CASSINI!!!!
spinbird
01-07-2004, 09:34
Originariamente inviato da Fede
e' telmente perfetto che sembra fatto al pc ;)
e l'uomo non è mai andato sulla luna?:rolleyes:
Originariamente inviato da Fede
e' telmente perfetto che sembra fatto al pc ;)
Perchè, tu credi di vedere delle imperfezioni o sbavature in una foto fatta da qualche milione di km con una risoluzione di qualche centinaio di km per pixel?
Ma ripeto la domanda: come dovrebbe essere?
Originariamente inviato da spinbird
e l'uomo non è mai andato sulla luna?:rolleyes:
Ovvio :O
Ci sono gli americani di mezzo :O
Questa volta però c'è anche l'ESA, forse qualche brandello di verità ci arriverà... :O
:D :D :D
Se guardi bene ci sono delle tempeste in alta quota...
Il fatto è che quelle immagini hanno una risoluzione mediocre...ed il risultato che vediamo è una interpolazione fatta al computer di vari frame successivi...
Originariamente inviato da cionci
Se guardi bene ci sono delle tempeste in alta quota...
Il fatto è che quelle immagini hanno una risoluzione mediocre...ed il risultato che vediamo è una interpolazione fatta al computer di vari frame successivi...
Mediocre? :mbe:
La risoluzione è la migliore che si sia mai ottenuta, è che essendo fatta credo di ricordare a più di un milione di km di distanza non puoi pensare di vedere dei particolari di qualche metro, come un'ombra frastagliata sugli anelli...
E non credo che sia interpolazione di frame successivi, se guardi sul sito della missione tra le foto raw trovi tutte le singole foto.
Frank1962
01-07-2004, 09:55
Originariamente inviato da gpc
Perchè? Come dovrebbe essere?
dovrebbe essere orientata come l'ombra sul pianeta e non in orizzontale, presumendo che l'unica fonte di illuminazione sia il sole
Ehm, se nessuno l'ha notato... Cassini-Huygens, la più costosa e complessa macchina scientifica creata dall'uomo è la prima sonda ad orbitare Il Signore degl Anelli, e la seconda ad orbitare un pianeta del sistema solare esterno.
3,3 miliardi di $ non sono andati persi, perchè una delle l'operazione più delicata in assoluto delle tre fasi centrali della missione (flyby di Venere, inserimento nell'orbita di Saturno, e la discesa di Hyugens su Titano), e l'unica la cui perfetta esecuzione era fondamentale per il successo dell'intera missione, è andata a buon fine, senza il minimo problema.
Parliamo di un evento scandito in minuti, preciso come un orologio, che avveniva a 880 milioni di km di distanza con una macchina che viaggiava a 69.000 km/h attraverso miliardi di massi e rocce degli anelli di Saturno.
Originariamente inviato da Frank1962
dovrebbe essere orientata come l'ombra sul pianeta e non in orizzontale, presumendo che l'unica fonte di illuminazione sia il sole
:mbe:
Mi sa che ti devi fare un ripassino di geometria...
In quella foto il sole è in basso, l'ombra è un cono che parte dal pianeta in direzione diagonale da basso-dx ad alto-sx.
Se metti gli anelli di mezzo ottieni una proiezione, ovviamente sul piano degli anelli, dell'ombra... ed ecco l'immagine che viene fuori. Normalissima geometria... che ha di strano?
Originariamente inviato da GioFX
Parliamo di un evento scandito in minuti, preciso come un orologio, che avveniva a 880 milioni di km di distanza con una macchina che viaggiava a 69.000 km/h attraverso miliardi di massi e rocce degli anelli di Saturno.
E sai cos'hanno usato come parasassi? L'antenna italiana :D
ARRIVAL! Cassini Enters Orbit Around Saturn
By Leonard David
Senior Space Writer
posted: 01:20 am ET
01 July 2004
BOULDER, COLORADO -- The Cassini tour bus to Saturn has arrived. After a nearly seven year journey, the spacecraft swung into an orbit around the giant gas globe tonight, ready to spend the next four years performing scientific investigations of the Saturnian system.
Beginning Wednesday evening, an engine on the nearly six-ton spacecraft throttled up and fired for more than 90 minutes, slowing Cassini down and placing it into an initial orbit around Saturn. That maneuver is called the Saturn Orbit Insertion, or SOI.
The SOI burn was critical to the success of the mission at Saturn. Cassini approached Saturn from below the planet’s ring plane, crossing through the large gap between the F Ring and G Ring.
Saturn's ring system is divided up into 7 major divisions, with the innermost ring to the outermost ring designated as D, C, B, A, F, G and E Ring. Each major ring division is further subdivided into thousands of individual "ringlets". These are made of ice particles and rocky material.
The spacecraft’s main engine was turned to face the direction of travel, and the resulting thrust from the engine acted as a braking device, slowing down the spacecraft as it entered Saturn's orbit.
Price tagged at over $3 billion, the mission is the most ambitious planetary mission ever conducted.
More moons?
Cassini’s engine burn lasted 96 minutes, placing the spacecraft into a highly elliptical orbit around Saturn.
The spacecraft’s closest approach to Saturn during its basic four-year tour occurred during the engine firing. The spacecraft's distance from Saturn was about 11,184 miles (18,000 kilometers), or less than a sixth of Saturn's diameter.
Cassini is now continuing to coast above the rings for approximately one hour and 44 minutes before its descent back through the ring plane.
As Cassini begins surveying the Saturnian system, ahead for the spacecraft is at least 76 orbits around the ringed planet, including 52 close encounters with seven of Saturn's 31 known moons. Scientists speculate that more moons orbiting the planet may still await discovery.
Extended mission
Program managers and scientists have already begun to discuss an extended Cassini mission, beyond the four-year primary mission. That extended mission might last 4 to 6 years, perhaps as much as 8 years if onboard fuel holds out.
Along with an array of science instruments, Cassini is toting the European Space Agency’s Huygens probe. The probe’s task is to parachute into the thick atmosphere of Titan -- Saturn's largest moon -- in mid-January of next year.
The Cassini-Huygens mission is an international undertaking led by three space agencies: NASA, the European Space Agency and the Italian space agency, Agenzia Spaziale Italiana (ASI). Seventeen nations contributed to building the spacecraft. The project is managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California.
Anxious scientists
Numbers of anxious space scientists have gathered here tonight at the Colorado University’s Laboratory for Atmospheric and Space Physics (LASP). And for good reason.
Onboard Cassini is a $12 million CU-Boulder instrument -- LASP's Ultraviolet Imaging Spectrograph, or UVIS. It is one of the 12 scientific instruments that the craft has hauled to Saturn.
The UVIS instrument package has a set of telescopes to measure UV light reflected by or emitted from Saturn's atmosphere, its rings and its moon atmospheres and surfaces. The data collected can determine their compositions, distribution, aerosol content and temperatures.
Name plate
Kip Denhalter, an electronics engineer at LASP helped build the UVIS instrument.
"There’s a sense of accomplishment. In the case of UVIS, an added feature on our flight instrument is that there’s a plate on the back to cover all the cables. All the people that worked on it, our names are nicely engraved on that plate. So we’ve got our names in orbit around Saturn, Denhalter said. "It’s kind of neat to point to Saturn and say I’ve got something I worked on out there," he told SPACE.com.
Alain Jouchoux, operations team leader for the UVIS, said he expects the device to keep working for many, many years – far beyond Cassini’s initial exploration goal of four years. "It can work forever," he confidently added.
Best photos in our lifetime
"Officially, we’re in orbit," said Jim Crocker, Vice President, Civil Space for Lockheed Martin Space Systems in neighboring Denver, Colorado. "We really needed to nail it and it looks like we did. This will give us a lot of science," he told SPACE.com in a phone interview.
Lockheed Martin built the spacecraft’s propulsion system, 16 thrusters, the nuclear power generators, and assembled a camera that is onboard the Huygens probe.
Crocker said imagery from Cassini is forthcoming. "These will be the best images of the rings that we’ll see in our lifetime," he added. "We’re very happy. Of course this is only the beginning. We’ve got four years to go and we’ll be firing up the engine a number of times."
Originariamente inviato da gpc
E sai cos'hanno usato come parasassi? L'antenna italiana :D
:asd:
DISTRUCTORS
01-07-2004, 10:01
Originariamente inviato da Frank1962
dovrebbe essere orientata come l'ombra sul pianeta e non in orizzontale, presumendo che l'unica fonte di illuminazione sia il sole
le solite inutili bagianate di chi non ha nulla da fare... bla bla bla...
parole parole parole....
ESA (http://www.esa.int/esaCP/index.html)
NASA (http://www.nasa.gov)
Guardate la nuova intro sul sito della NASA...
Originariamente inviato da gpc
Mediocre? :mbe:
La risoluzione è la migliore che si sia mai ottenuta, è che essendo fatta credo di ricordare a più di un milione di km di distanza non puoi pensare di vedere dei particolari di qualche metro, come un'ombra frastagliata sugli anelli...
E non credo che sia interpolazione di frame successivi, se guardi sul sito della missione tra le foto raw trovi tutte le singole foto.
http://saturn.jpl.nasa.gov/multimedia/images/small-moons/images/PIA06400.jpg
Qui c'è scritto che la prima foto è un"mosaic"... Mi è venuto questo da pensare... La distanza è 16000 Km se non sbaglio... Magari forse perchè è piccola...
Originariamente inviato da cionci
http://saturn.jpl.nasa.gov/multimedia/images/small-moons/images/PIA06400.jpg
Qui c'è scritto che la prima foto è un"mosaic"... Mi è venuto questo da pensare... La distanza è 16000 Km se non sbaglio... Magari forse perchè è piccola...
Non mi pare che sia esattamente la stessa foto :D
Comunque sì, quella è un mosaico perchè se non erro non è stata utilizzata la wide angle camera ma l'altra per avere foto più dettagliate, e poi ovviamente è stato fatto il mosaico.
Quella foto di Saturno invece dovrebbe essere una delle ultime fatte finchè il pianeta e gli anelli stavano all'interno dell'obiettivo.
Immagine in alta risoluzione:
http://photojournal.jpl.nasa.gov/jpeg/PIA06077.jpg
Saturn's peaceful beauty invites the Cassini spacecraft for a closer look in this natural color view, taken during the spacecraft's approach to the planet. By this point in the approach sequence, Saturn was large enough that two narrow angle camera images were required to capture an end-to-end view of the planet, its delicate rings and several of its icy moons. The composite is made entire from these two images.
Moons visible in this mosaic: Epimetheus (116 kilometers, 72 miles across), Pandora (84 kilometers, 52 miles across) and Mimas (398 kilometers, 247 miles across) at left of Saturn; Prometheus (102 kilometers, 63 miles across), Janus (181 kilometers, 113 miles across) and Enceladus (499 kilometers, 310 miles across) at right of Saturn.
The images were taken on May 7, 2004 from a distance of 28.2 million kilometers (17.6 million miles) from Saturn. The image scale is 169 kilometers (105 miles) per pixel. Moons in the image have been brightened for visibility.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras, were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
Originariamente inviato da GioFX
The images were taken on May 7, 2004 from a distance of 28.2 million kilometers (17.6 million miles) from Saturn. The image scale is 169 kilometers (105 miles) per pixel.
Le so tutteeeeeeeee :sborone:
:D
Frank1962
01-07-2004, 10:25
Originariamente inviato da gpc
:mbe:
Mi sa che ti devi fare un ripassino di geometria...
In quella foto il sole è in basso, l'ombra è un cono che parte dal pianeta in direzione diagonale da basso-dx ad alto-sx.
Se metti gli anelli di mezzo ottieni una proiezione, ovviamente sul piano degli anelli, dell'ombra... ed ecco l'immagine che viene fuori. Normalissima geometria... che ha di strano?
no non c'è bisogno del ripassino ....tanto ci sei tu che 6 ing; cmq hai ragione ....quello che mi fregava era l'elisse dell'anello in rapporto alla sfera del pianeta.
cmq tra tutti i pianeti che hanno fotografato sicuramente il nostro è il più figo :D
Frank1962
01-07-2004, 10:27
Originariamente inviato da DISTRUCTORS
le solite inutili bagianate di chi non ha nulla da fare... bla bla bla...
parole parole parole....
ma chi sei un bambino? un adolescente? ....impara a comportarti e forse capirai che si può rispondere anche a modo :rolleyes:
DOWNLINK DELLE IMMAGINI IN QUESTO ISTANTE
NASA TV (http://www1.nasa.gov/ram/35037main_portal.ram)
Che cacchio è quell'immagine ?
Originariamente inviato da cionci
Che cacchio è quell'immagine ?
si tratta delle prime immagini di alcune delle fascie interne (credo) degli anelli, C o D credo...
Non mi rubate la banda che dopo va a scatti :O
:D
ma perchè devono sempre avere la megabandiera dietro... :nono:
:sofico:
Se vi interessa qui c'è una bella animazione che spiega cosa ha fatto e farà in queste ore la sonda.
http://www.esa.int/SPECIALS/Cassini-Huygens/index.html
spinbird
01-07-2004, 14:41
Originariamente inviato da GioFX
ma perchè devono sempre avere la megabandiera dietro... :nono:
:sofico:
perchè stanno in america:D
edit: non vedo più le immagini in broadcast...staccatevi che mi ciulate banda:p
Originariamente inviato da spinbird
perchè stanno in america:D
no, solo perchè sò ammericani... :D
beh,, quanto meno hanno messo il poster con i loghi di ESA e ASI... :D
spinbird
01-07-2004, 14:45
Originariamente inviato da GioFX
beh,, quanto meno hanno messo il poster con i loghi di ESA e ASI... :D
non si vede piùna sega:muro:
Bei monitor che hanno :fagiano:
Originariamente inviato da gpc
Bei monitor che hanno :fagiano:
si, sono 19" LCD! e poi, hai visto i 16:9 da almeno 30"? :D
Originariamente inviato da GioFX
si, sono 19" LCD! e poi, hai visto i 16:9 da almeno 30"? :D
Sì :sbav:
Comunque è una mia impressione o hanno tagliato di brutto il collegamento interropendo l'intervistatrice mentre parlava? :D
Originariamente inviato da gpc
Sì :sbav:
Comunque è una mia impressione o hanno tagliato di brutto il collegamento interropendo l'intervistatrice mentre parlava? :D
no, credo fosse concluso il collegamento... era incerta se stessero annunciando o meno qualcosa... cmq tra poco ci sarà una nuova press conference.
Sul discorso dell'antenna usata come parasassi... si vede che quello è il posto della nostra nazione nel cosmo! :D :D :D
Beh, meglio così che non averlo il posto, vero? ;)
Scherzi a parte, il contributo italiano è veramente importante.
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS02/N00006483.jpg
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS02/N00006479.jpg
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS02/N00006476.jpg
Schummacherr
01-07-2004, 16:42
Ci sono anche io :O :D
Originariamente inviato da Schummacherr
Ci sono anche io :O :D
Su Saturno? A cavalcioni di Cassini? :D
First pictures from Saturn orbit show rich ring detail
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 1, 2004
The first batch of photographs snapped by the Cassini Saturn orbiter earlier today reached the Jet Propulsion Laboratory around 8:30 a.m., zoomed-in shots of the planet's myriad rings showing a ghostly tapestry of icy, back-lit particles arrayed in sharply defined bands.
http://spaceflightnow.com/cassini/images/040701rings1.jpg
One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
Much brighter shots showing the rings from the sunlit side were expected to reach Earth later this morning, but scientists were elated at the initial results.
"Look at that structure, it's so regular!" marveled imaging team leader Carolyn Porco as a picture came in showing well-defined bands of brightness and darkness. "I'm wondering if we're looking at a density wave. This looks like it might be a density wave, but I'm not quite sure."
Density waves, caused by gravitational interactions with nearby moons, are thought to be "kissing cousins" of the waves that produce the spiral structure seen in galaxies like Earth's Milky Way.
"These are regions where the rings are communicating gravitationally with the moons exterior to them," Porco explained.
One of the objectives of Cassini's ring research is to study density waves in unprecedented detail and based on the first set of images, scientists will not be disappointed.
"With these kinds of images and with the data we're going to return from Cassini with stellar occulation observations, radio occulation observations, we are going to nail density waves, we are going to understand these critters," Porco said. "This is really a new era in the study of outer planet systems."
A few moments later: "There goes another one, which is mind blowing, absolutely mind blowing," Porco exclaimed. "Look at thatOoh... It's almost everywhere you look here, you can't miss one. They're just all over the place."
A few moments later: "Oh my God, look at that! ... These density waves are like books, just waiting to be read."
But this morning, as raw, unprocessed images flowed in, science wasn't the immediate objective. It was enough just to know Cassini's camera and other systems had worked as planned during close approach to Saturn.
The photo sequence began around 12:30 a.m., 18 minutes or so after Cassini finished a 96-minute rocket firing to brake into orbit around Saturn. Streaking just above the rings at speeds greater than 50,000 mph, Cassini's narrow-angle camera took a series of snapshots, opening its shutter for just five milliseconds per picture to avoid blurring.
http://spaceflightnow.com/cassini/images/040701rings2.jpg
One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
Each picture was separated from those on either side by about 600 miles because of Cassini's extreme velocity.
"We couldn't take a contiguous ring scan with images overlapping other images because we are speeding across the rings very fast," Porco said. "It takes us about a minute to take a picture and so in the time we shutter the exposure, read out the camera and get ready to take a picture again, we have crossed a thousand kilometers. Our field of view is only about, let's say, 100 to 200 kilometers. So never do we have overlapping images. Never will we be able to put this all together in a nice mosaic."
One of the world's leading ring experts, even Porco was surprised by the level of detail apparent in the first unprocessed pictures.
"I shouldn't be, I suppose, but I am surprised," she reflected. "You can think about this like we have done for 14 years and you know, well, we'll get density waves there and we'll take pictures. But it's remarkable to me at how startling it is to see these images for the first time. ... They're just beautiful, they're very sharp."
One picture that came in about an hour after the first image was received was especially intriguing, showing a density wave on the left with narrower and narrower bands of light and dark and a so-called bending wave on the right.
"Oh my God! This is, oh, this is really exciting!" Porco exclaimed. "If you look, the pattern now is decreasing to the left and that is the mark of a bending wave. ... And a bending wave, it's not the density of the particles that is being moderated or modified as you move across the rings, but it is the height of the ring plane. The darkness is created by shadows. Look at that! It's just a beautiful pair."
cose da non credere... 810 km tra un'immagine e l'altra e ma soli 5 millisecondi di apertura del "diaframma"... infatti l'ernome velocità avrebbe reso le immagini sfocate con tempi di esposizione superiori!
Peccato non avere un filmatino... :D Ma suppongo che verrebbe un po' mosso... :D
Schummacherr
01-07-2004, 17:16
Originariamente inviato da gpc
Su Saturno? A cavalcioni di Cassini? :D
:D :D :D :D LOL :D :D :D :D
vi scrivo da lì infatti..non sapete che spettacolo sti anelli...solo ke ogni tanto mi arriva qualche roba strana in testa :what: si gira forte quissù :D
Scientists marvel at photos
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 1, 2004
Making gravity visible, close-up images of Saturn's rings shot by NASA's newly arrived Cassini probe revealed an intricate, never-before-seen tapestry of icy particles herded into spiralling density waves by the effects of nearby moons.
http://spaceflightnow.com/cassini/images/040701rings5.jpg
One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
Carolyn Porco, leader of the Cassini camera team, a serious Beatles fan and one of the world's leading authorities on Saturn's ring system, was almost at a loss for words describing her initial impressions of the new vistas opened up by Cassini.
"I don't think you have to be a ring scientist to imagine what last night was like to us," she said of the spacecraft's arrival in Saturn orbit and the initial batch of ring pictures beamed back to Earth early today. "It was beyond description, it was mind blowing, it was every adjective you could think of.
"Even though we've had a long time to think about our images ... I'm surprised at how surprised I am at the beauty and the clarity of these images. They are shocking to me. You are going to see some images now, they were so shocking I thought my team here was playing tricks on me and showing me a simulation of the rings and not the rings themselves. It's just utterly remarkable."
Cassini snapped 61 black-and-white pictures of Saturn's rings early today after completing a 96-minute rocket firing to brake into orbit around the ringed planet. Program manager Bob Mitchell reported this afternoon that engineering data radioed back from Cassini shows the spacecraft survived two ring plane crossings without incident and that all of its myriad subsystems were in good health and operating normally.
Cassini skimmed over the top of the rings as it braked into orbit and shortly after main engine shut down, the spacecraft began carrying out commands to photograph the rings, first from the upper backlit side and then from below, where the thin disk of icy particles was bathed in direct sunlight.
Because of Cassini's enormous velocity - 60,000 mph or so at engine cutoff - its cameras were programmed with shutter speeds of five thousandths of a second to prevent blurring. In the minute required to snap a picture, record the data and be ready for another shot, Cassini moved hundreds of miles, preventing researchers from taking overlapping photos or the multiple images required for color.
But no one was complaining.
http://spaceflightnow.com/cassini/images/040701rings4.jpg
http://spaceflightnow.com/cassini/images/040701rings4.jpg
"The Cassini cameras are far more capable than the Voyager cameras were, which is in large part why these images are so spectacular," Porco said. "The other part, of course, is that the spacecraft gives us a very steady platform. This machine, you turn it, you point it and it stays there. It's like a tripod in space. So it allows us to take very sharp images."
Cassini will never again fly so close to the rings and the level of detail the craft's cameras captured was stunning. If there was a central theme to the pictures it was the ubiquitous presence of density waves, regions of alternating brightness and darkness that look like ripples in fine sand. The spacing of the ripples, caused by gravitational interactions with nearby moons, decreases as one moves outward from the planet.
"This is a telltale sign of a density wave, the wavelengths decreases as you go outward and also the amplitude of the wave damps so you see it disappear," Porco said, describing one picture. "These are characteristics ring scientists read like a book to discern what kind of properties the particles have, how densely they're packed and so on. As I said, this is unprecedented resolution for the imaging experiment."
One image showed a density wave thinning out to the right and a so-called bending wave moving to the left across the field of view.
In a bending wave, "it's not the number density of particles that is varying, it is literally the height of the ring plane," Porco said. "You can think of the feature on the right as being like corrugated cardboard where the ring is literally warped and its warped because the moons which are exciting that particular wave excite inclination (tilt) in the particle orbits and the particle orbits get phased in such a way that it forms this pattern, which in fact is a spiral pattern.
"If you followed it around the rings, it would take the spiral form," she said. "These are similar to the spiral arms of spiral galaxies."
Describing a blow up of a density wave image, Porco pointed out strange looking structures that "almost looks like straw. I don't know what this is. We think it's real, we see it in other images. ... So it's not some noise pattern in the image.
"There may be processes going on that make the particles clump on scales that you're seeing here. ... Nonetheless we're seeing something here and I literally don't have a clue. This may be brand new, something no one's ever predicted before."
The picture Porco initially thought was a joke was focused on a gap in the outer A ring known as the Encke division, a narrow void swept out by the tiny moon Pan. Along with showing ultra clear views of spiralling density waves on both sides of the gap, the ring material forming the inner edge had a sharply scalloped appearance. Even to the layman, the picture appeared unusual.
http://spaceflightnow.com/cassini/images/040701rings3.jpg
One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
"It just doesn't look real," Porco marveled. "It's so sharp, the wakes that you see in the interior to the Encke gap, you can see the classic scalloped edges. These are caused by gravitational impulses by Pan - there may be other moons there, we don't know - which force eccentricities in the orbits of the particles on the edge of the gap. With repeated passages of the moon ... it builds up this sinusoidal pattern, this beautiful classic pattern.
"This is like textbook physics, textbook ring physics right there in one image," she said.
At a news conference Porco was asked why the study of Saturn's rings was important.
"This is standard ring lore, that Saturn's rings especially are our closest analogue of the celestial disk system," she began. "Frank Shu, an astrophysicist, said this many years ago: there are two types of bodies in the universe. There are spheres and there are disks. And under certain circumstances, a sphere can collapse down into a disk and that's what will happen if you have a spherical cloud of debris and the particles are colliding, they lose energy but they preserve angular momentum and they all end up in a plane. That's a very common process and its given rise to lots of disk system.
"One is Saturn's rings, one was the solar nebula out of which our solar system and the planets formed. Astronomers now see lots of disks around other stars and even reaching way far out in size to the spiral galaxies, they are another disk system. Common physics applies to all of them.
"So in studying rings, we hope to study processes that go on in disks in general," Porco said. "And so we think we're seeing in Saturn's rings some of the processes that went on in the solar nebula before the planets formed. In fact, we may be seeing some of the processes that actually aided the development of the planets."
If one is interested in "understanding where the solar system came from or how it got here, how the planets were formed, then this is the place to go."
Ed Weiler, an astronomer by training who serves as NASA's associate administrator for space flight, offered another reason to study Saturn and its rings.
"When I was growing up, this kind of stuff was science fiction," he said. "We compete with a lot of things: Game Boys, X-Boxes and Play Stations. This isn't science fiction, we actually did this. We're in orbit around another planet taking these kinds of pictures with an incredible machine. We did this. This isn't animation, this isn't PowerPoint, this is real. I like data, and this is real data.
"So I hope we can excite at least a few more kids in this country to become scientists and engineers. If we can do that, it was worth every penny we spent on it."
"It just doesn't look real," Porco marveled. "It's so sharp, the wakes that you see in the interior to the Encke gap, you can see the classic scalloped edges. These are caused by gravitational impulses by Pan - there may be other moons there, we don't know - which force eccentricities in the orbits of the particles on the edge of the gap. With repeated passages of the moon ... it builds up this sinusoidal pattern, this beautiful classic pattern.
"This is like textbook physics, textbook ring physics right there in one image," she said.
At a news conference Porco was asked why the study of Saturn's rings was important.
"This is standard ring lore, that Saturn's rings especially are our closest analogue of the celestial disk system," she began. "Frank Shu, an astrophysicist, said this many years ago: there are two types of bodies in the universe. There are spheres and there are disks. And under certain circumstances, a sphere can collapse down into a disk and that's what will happen if you have a spherical cloud of debris and the particles are colliding, they lose energy but they preserve angular momentum and they all end up in a plane. That's a very common process and its given rise to lots of disk system.
"One is Saturn's rings, one was the solar nebula out of which our solar system and the planets formed. Astronomers now see lots of disks around other stars and even reaching way far out in size to the spiral galaxies, they are another disk system. Common physics applies to all of them.
"So in studying rings, we hope to study processes that go on in disks in general," Porco said. "And so we think we're seeing in Saturn's rings some of the processes that went on in the solar nebula before the planets formed. In fact, we may be seeing some of the processes that actually aided the development of the planets."
If one is interested in "understanding where the solar system came from or how it got here, how the planets were formed, then this is the place to go."
Ed Weiler, an astronomer by training who serves as NASA's associate administrator for space flight, offered another reason to study Saturn and its rings.
"When I was growing up, this kind of stuff was science fiction," he said. "We compete with a lot of things: Game Boys, X-Boxes and Play Stations. This isn't science fiction, we actually did this. We're in orbit around another planet taking these kinds of pictures with an incredible machine. We did this. This isn't animation, this isn't PowerPoint, this is real. I like data, and this is real data.
"So I hope we can excite at least a few more kids in this country to become scientists and engineers. If we can do that, it was worth every penny we spent on it."
Ma stavolta non ci sono le immagini da mille mila pixel? :(
Originariamente inviato da Spike
Ma stavolta non ci sono le immagini da mille mila pixel? :(
emh... a parte che le immagini della pancam dei robot MER sono da 1 MP (le immagini in altissima risoluzione sono fatte grazie alle fantastiche lenti che montano), cmq queste immagini sono solo quelle scattate brevemente alla fine della fase SOI...
Ma poi di cosa sono fatti gli anelli ?
line, rocce, sassi e polvere interstellare... che si dispone in fasce staccate a causa dell'influenza della magnetosfera (il campo magnetico di saturno) e dalla forze esercitate dalle lune più grandi.
ehm... non vorrei sfogliare tutto il 3d, ma a che distanza è arrivato dagli anelli?
Originariamente inviato da Bet
ehm... non vorrei sfogliare tutto il 3d, ma a che distanza è arrivato dagli anelli?
C'è passato in mezzo.
Pigro.
:D :D :D
Originariamente inviato da gpc
C'è passato in mezzo.
Pigro.
:D :D :D
opss... ma è la terza foto che ha pubblicato in questa pagina? (pigro al quadrato :D )
Originariamente inviato da Bet
opss... ma è la terza foto che ha pubblicato in questa pagina? (pigro al quadrato :D )
Mi dà anche del lei? :O
Direi di no comunque, non ho visto foto del momento in cui li attraversava (comunque è passato ovviamente per una delle fasce libere, va bene che avevano il parasassi italiano, però non era salutare usarlo a spazzaneve :D ).
In ogni caso la scuso per la sua pigrizia solo in ragione della sua veneranda età :O
Originariamente inviato da gpc
Mi dà anche del lei? :O
...
doppio opss...
Vi daro' del Voi :D
ps: prima o poi ti chiedero' consulenza sull'acquisto di un telescopio (economico naturalmente)
Originariamente inviato da Bet
doppio opss...
Vi daro' del Voi :D
ps: prima o poi ti chiedero' consulenza sull'acquisto di un telescopio (economico naturalmente)
Economico? Non lo sarà più nel momento in cui dovrai pagare la mia consulenza :O
:D
Certo comunque, quando vuoi... chiedi anche a Sweethawk che ne ha comprato uno da poco (il porcello... ).
Cassini exposes Saturn's two-face moon Iapetus
CASSINI PHOTO RELEASE
Posted: July 15, 2004
The moon with the split personality, Iapetus, presents a perplexing appearance in the latest images snapped by the Cassini spacecraft.
http://spaceflightnow.com/cassini/images/040715iapetus.jpg
Credit: NASA/JPL/Space Science Institute
One hemisphere of the moon is very dark, while the other is very bright. Scientists do not yet know the origin of the dark material or whether or not it is representative of the interior of Iapetus.
Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known moons. Its diameter is about one third that of our own moon at 1,436 kilometers (892 miles). This image was taken in visible light with the Cassini spacecraft narrow angle camera on July 3, 2004, from a distance of 3 million kilometers (1.8 million miles) from Iapetus. The brightness variations in this image are not due to shadowing, they are real.
During Cassini's four-year tour, the spacecraft will continue to image Iapetus and conduct two close encounters. One of those encounters, several years from now, will be at a mere 1,000 kilometers (622 miles).
Iapetus was discovered by the Italian-French astronomer Jean Dominique Cassini in 1672. He correctly deduced that the trailing hemisphere is composed of highly reflective material, while the leading hemisphere is strikingly darker.
This sets Iapetus apart from Saturn's other moons and Jupiter's moons, which tend to be brighter on their leading hemispheres. Voyager images show that the bright side of Iapetus, which reflects nearly 50 percent of the light it receives, is fairly typical of a heavily cratered icy satellite. The leading side consists of much darker, redder material that has a reflectivity of only about 3 to 4 percent.
One scenario for the outside deposit of material has dark particles being ejected from Saturn's little moon Phoebe and drifting inward to coat Iapetus. One observation lending credence to an internal origin is the concentration of material on crater floors, which is suggestive of something filling in the craters.
Iapetus is odd in other respects. It is in a moderately inclined orbit, one that takes it far above and below the plane in which the rings and most of the moons orbit. It is less dense than many of the other satellites, which suggests a higher fraction of ice or possibly methane or ammonia in its interior.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
von Clausewitz
19-07-2004, 23:36
Originariamente inviato da GioFX
line, rocce, sassi e polvere interstellare
che so le line?
la polvere trattandosi di un sistema come quello di saturno, più che interstellare sarà interplanetaria
gli anelli di saturno sono rosa e grigi...
http://www.corriere.it/Media/Foto/2004/07_Luglio/23/saturno.jpg
La foto a colori naturali della sonda Cassini
Saturno: gli anelli sono di colore rosa e grigio
L'immagine ripresa il 21 giugno a 6,4 milioni di chilometri, poco prima dell'ingresso in orbita del satellite intorno al pianeta
PASADENA - Rosa e grigio con un po' di marrone. Sono i colori reali degli anelli di Saturno come risultano dalla prima immagine a colori naturali inviata dalla sonda Cassini. La foto è stata ripresa il 21 giugno scorso a una distanza di 6,4 milioni di chilometri, poco prima dell’ingresso in orbita di Cassini intorno a Saturno. Gli anelli sono composti soprattutto di ghiaccio, che quando è puro è di coloro bianco. Gli scienziati pensano che le le diverse colorazioni dipendano dalla presenza di altri materiali frammisti al ghiaccio. Le immagini precedenti degli anelli inviate da Cassini erano in bianco e nero, o riprese all’infrarosso.
IL LUNGO VIAGGIO - Nella notte tra il 30 giugno e il primo luglio scorso si è concluso il lungo viaggio della sonda Cassini: tre miliardi e mezzo di chilometri, in sette anni, attraverso il nostro sistema solare. Cassini adesso studierà Saturno per i prossimi 4 anni, mentre la sonda Huygens deve ancora affrontare la fase più difficile della missione, la discesa su Titano, la più grande delle lune di Saturno. Discesa prevista per il 14 gennaio e che ci riporterà indietro nel tempo, dato che Titano sembra avere la stessa costituzione della Terra ai suoi primordi. La missione Cassini-Huygens sembra un nuovo successo, quello sinora più importante: l'essere giunta, primo manufatto umano, nel sistema di Saturno per restarci. Un successo anche molto italiano come ha detto l'Amministratore della NASA, Sean O'Keefe, nel salutare il successo dell'operazione ricordando l'enorme supporto dell'Agenzia Spaziale Italiana e la stretta collaborazione tra le due agenzie.
23 luglio 2004 - Corriere.it
La sonda Cassini scopre 2 nuove lune di Saturno!
http://news.bbc.co.uk/1/hi/sci/tech/3571564.stm
già, una bella collezione!
17 ago 16:58 Saturno: due nuove lune scoperte dalla sonda Cassini
WASHINGTON - Sale a 33 il numero delle lune che orbitano attorno a Saturno. La sonda spaziale Cassiniha scoperto due nuove lune, avvicinandosi al pianeta. I due satelliti hanno un diametro di 3,2 chilometri e di 4 chilometri.I ricercatori della Nasa hanno affermato che continueranno a studiare con grande minuzia le immagini inviate dalla sonda Cassini nella speranza di scoprire nuovi dettagli sulle due nuove lune (per adesso battezzate 'S/2004 S1' e 'S/2004 S2').(Agr)
per chi ancora nn ho visto La sonda....
http://www-pao.ksc.nasa.gov/kscpao/images/large/97pc1019.jpg
jumpermax
24-10-2004, 22:43
Ragazzi titano si avvicina.... il primo passaggio attorno a Titano tra meno di 36 ore...
http://saturn.jpl.nasa.gov/
On Tuesday, Oct. 26, Cassini will pass within 1,200 km (746 miles) of Saturn's giant moon Titan. The historic flyby will be the closest approach to Titan to date. NASA TV coverage begins Oct. 26 at 6:30 p.m. (PST).
http://saturn.jpl.nasa.gov/multimedia/images/titan/images/image18.jpg
jumpermax
26-10-2004, 00:49
ci avviciniamo.... la x non è il punto dove bisogna scavare.... ;)
http://saturn.jpl.nasa.gov/multimedia/images/titan/images/PIA06116.jpg
Zooming In On Titan
October 25, 2004 Full-Res: PIA06116
This map of Titan's surface, generated from images taken during Cassini's approach to Saturn, illustrates the imaging coverage planned during Cassini's first very close Titan flyby on Oct. 26, 2004.
Colored lines enclose regions that will be covered at different imaging scales as Cassini approaches Titan. Based on previous observations, it is anticipated that the size of the smallest visible surface features will be approximately five times larger than the image scale. Thus, the smallest visible features within the region bounded by the red curve should be about 1 to 1.2 kilometers (0.6 to 0.9 mile) across. The yellow X marks the predicted landing site for the Huygens probe, the target of the camera's highest-resolution mosaic. Images of this site taken near closest approach may have higher resolution than indicated here. Features a few hundred meters or yards across may be discernible, depending on the effect that relative motion between the spacecraft and Titan has on the quality of the images.
The images used to create the map were acquired between April and June 2004 using a narrow, 938-nanometer filter that sees through Titan's atmospheric haze to the surface. These images have been processed to enhance surface details. Scales range from 88 to 35 kilometers (55 to 22 miles) per pixel. It's currently winter in Titan's northern hemisphere, so high northern latitudes are not illuminated, resulting in the map's upper limit at roughly 45 degrees north latitude
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .
jumpermax
27-10-2004, 09:59
http://saturn.jpl.nasa.gov/cgi-bin/gs2.cgi?path=../multimedia/images/titan/images/vims-1.jpg&type=image
http://saturn.jpl.nasa.gov/multimedia/images/titan/images/vims-1.jpg
Window to Titan's Surface
October 26, 2004
This movie taken by the Cassini spacecraft shows the surface and atmosphere of Saturn's moon Titan over a range of infrared wavelengths, from .8 to 5.1 microns. It was captured by Cassini's visual and infrared mapping spectrometer on Oct. 26, 2004, as the spacecraft flew by Titan at an altitude of approximately 450,000 kilometers (280,000 miles). At specific wavelengths, surface features can be seen through Titan's haze, while at other wavelengths, the surface remains completely hidden.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The visible and infrared mapping spectrometer team is based at the University of Arizona, Tucson.
For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov. For more information about the visual and infrared mapping spectrometer visit http://wwwvims.lpl.arizona.edu/.
Image Credit:
NASA/JPL/University of Arizona
E' un'immagine presa all'infrarosso, fa parte di un filmato che analizza una porzione dello spettro... da notare la zona luminescente in basso a destra, in diverse parti dello spettro.....
jumpermax
27-10-2004, 17:22
http://saturn.jpl.nasa.gov/multimedia/images/titan/images/PIA06139.jpg
Titan in False Color
October 27, 2004 Full-Res: PIA06139
This image shows Titan in ultraviolet and infrared wavelengths. It was taken by Cassini's imaging science subsystem on Oct. 26, 2004, and is constructed from four images acquired through different color filters. Red and green colors represent infrared wavelengths and show areas where atmospheric methane absorbs light. These colors reveal a brighter (redder) northern hemisphere. Blue represents ultraviolet wavelengths and shows the high atmosphere and detached hazes.
Titan has a gigantic atmosphere, extending hundreds of kilometers above the surface. The sharp variations in brightness on Titan's surface (and clouds near the south pole) are apparent at infrared wavelengths. The image scale of this picture is 6.4 kilometers (4 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
For the latest news about the Cassini-Huygens mission, visit http://www.nasa.gov/cassini. For more information about the mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .
Image Credit:
NASA/JPL/Space Science Institute
atmosfera davvero spessa.... :eek:
hanno capito di cosa è composta l'atmosfera ?
jumpermax
28-10-2004, 11:41
Originariamente inviato da cionci
hanno capito di cosa è composta l'atmosfera ?
un po' di tutto benzene,metano, azoto, idrogeno...
http://saturn.jpl.nasa.gov/multimedia/images/titan/images/PIA06980.jpg
Lots of Hydrocarbons
October 27, 2004 Full-Res: PIA06980
This graph shows data acquired by Cassini as it flew by Titan at an altitude of 1,200 kilometers (745 miles) on Oct. 26, 2004 - its closet approach yet to the hazy moon. The data is from Cassini's ion and neutral mass spectrometer, which detects charged and neutral particles in the atmosphere. The graph reveals a diversity of hydrocarbons in the high atmosphere above Titan, including benzene and diacetylene.
http://saturn.jpl.nasa.gov/cgi-bin/gs2.cgi?path=../multimedia/images/titan/images/PIA06980.jpg&type=image
Qua invece parlano dell'azoto più specificatamente...
http://saturn.jpl.nasa.gov/cgi-bin/gs2.cgi?path=../multimedia/images/titan/images/PIA06981.jpg&type=image
Originariamente inviato da jumpermax
un po' di tutto benzene,metano, azoto, idrogeno...
mmmh, che ambiente salubre :D
STANOTTE SGNACIO DI HYUGENS SU TITANO
http://www.esa.int/esaCP/SEMWRK3AR2E_index_0.html
Huygens probe ready to detach from Cassini mother craft
24 December 2004
After a seven-year and 3.2 billion km journey from Earth to Saturn, ESA’s Huygens probe, travelling on board NASA’s Cassini mother craft and powered through an umbilical cable, is now ready to separate and continue its journey alone toward Titan, Saturn’s largest moon.
On Christmas night (25 December at 03:00 CET- orbiter time/04:08 CET on the ground) Huygens will be cut loose from Cassini and will coast toward Titan for 20 days, to arrive at its destination on 14 January.
“We have the green light for separation. The joint ESA/NASA team has done all that had to be done to be ready for release. We are looking forward to receiving data on 14 January at ESA’s Spacecraft Operations Centre in Darmstadt, Germany.”, said Claudio Sollazzo, ESA’s Head of Huygens Spacecraft Operations Unit at NASA/JPL in Pasadena, California.
Artist's impression of Huygens just before entry
At separation, tension-loaded springs will gently push Huygens away from Cassini onto a ballistic 4-million kilometre path to Titan. The Huygens probe will remain dormant until the on-board timer, which has been loaded on 21 December, wakes it up shortly before it reaches Titan's upper atmosphere on 14 January.
“We will then have to wait patiently for the most exciting phase of our mission, when Cassini will send back to Earth the Huygens data. The Huygens descent will be accomplished in less then two and half hours and, if the probe survives the impact with the surface, we could expect up to two extra hours of science results before the onboard batteries die out” said Jean-Pierre Lebreton, ESA’s Huygens Mission Manager and Project Scientist, preparing to follow the separation from NASA/JPL in Pasadena.
At about 1200 km above the surface of Titan, the Huygens probe will begin a dramatic plunge through Titan’s thick haze, with the task to analyze the chemical makeup and composition of the moon’s atmosphere as it descends to touchdown on its surface. With Cassini listening to the probe for 4.5 hours, the data gathered during the descent and on the surface will be transmitted continuously by the probe and recorded onboard the Cassini orbiter.
Cassini will then turn away from Titan and point its antenna to Earth and relay the data through NASA's Deep Space Network to JPL and on to ESA's Space Operations Centre ESOC in Darmstadt, Germany where the Huygens probe data will be analysed by scientists.
After a successful probe release, on 28 December, the Cassini orbiter will perform a deflection manoeuvre to keep it from following Huygens into Titan's atmosphere and to establish the required geometry between the probe and the orbiter for radio communications during the probe’s descent. The Cassini-Huygens mission is a cooperation between NASA, the European Space Agency and ASI, the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, is managing the mission for NASA’s Office of Space Science, Washington.
ottimo, stavo cercando giusto info. ;)
eheh, ogni tanto i grandi passi li facciamo ancora :)
Da Spaceflightnow.com (http://spaceflightnow.com/cassini/041224huygens.html):
Huygens probe set for release from Cassini orbiter
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: December 24, 2004
Editor's note... All times in the following story refer to Earth-received time, i.e., when events are confirmed to have happened, not the actual time an event happens at Saturn. One-way light time from Saturn to Earth currently is about 68 minutes.
A European-built probe carrying cameras and a suite of scientific instruments is primed for release from NASA's Cassini Saturn orbiter Christmas Eve, setting up a dramatic Jan. 14 plunge into the atmosphere of the ringed planet's mysterious moon Titan.
http://spaceflightnow.com/cassini/images/040612huygensdescent.jpg
An artist's concept shows the Huygens craft making its descent to Titan on Jan. 14. Credit: ESA
Ejected by springs that will impart a 7 rpm rotation for stability, the Huygens probe is scheduled for release from the Cassini mothership at 10:08 p.m. EST (0308 GMT). Cassini's antenna will be pointed away from Earth at the moment of release, but communications should be restored shortly before 11 p.m. when engineers expect to confirm separation. If all goes well, the flying saucer-shaped probe will slam into Titan's hydrocarbon atmosphere around 5:13 a.m. Jan. 14 at a velocity of some 12,400 mph.
Descending through the moon's smoggy atmosphere under parachutes, Huygens will finally reach the surface some two-and-a-half hours after atmospheric entry. Throughout the descent, data from Huygens' instruments will be transmitted to Cassini, flying past the moon nearly 40,000 miles away, stored on digital recorders and later re-transmitted to Earth.
Huygens represents one of the most ambitious space projects ever attempted by the European Space Agency and one that if successful, will reveal a new world to the gaze of eager scientists. While Cassini is re-writing the textbooks about Saturn, its rings and several of its many moons, its cameras and cloud-penetrating radar cannot clearly see through Titan's atmosphere. That's where Huygens comes in.
The stage was set for the probe's long-awaited Christmas Eve release on Dec. 16 when flight controllers at the Jet Propulsion Laboratory in Pasadena, Calif., carried out orbital trim maneuver No. 8, an 84.9-second main engine firing that put Cassini - and Huygens - on a collision course with Titan.
"As partners with ESA, one of our obligations was to carry the Huygens probe to Saturn and drop it off at Titan," Robert Mitchell, Cassini program manager, said in a statement. "We've done the first part, and on Christmas Eve we will release Huygens and tension-loaded springs will gently push it away from Cassini onto a ballistic free-fall path to Titan."
On Dec. 27, Cassini's engine will be fired again to move the mother ship off the Huygens impact trajectory and set up the proper geometry to relay data during the entry probe's descent.
A timeline of critical upcoming events is available here (http://spaceflightnow.com/cassini/041224timeline.html).
To reach Titan's surface, Huygens first must survive its high-speed plunge into the moon's atmosphere. After slowing to about 870 mph due to atmospheric friction, Huygens' aft cover will be pulled away by a pilot chute and the spacecraft's 27-foot-wide main parachute will deploy. The chute will be jettisoned 15 minutes after entry begins and from that point on, Huygens will ride beneath a smaller 9.8-foot-wide parachute. Impact on the surface at some 11 mph is expected around 7:31 a.m. on Jan. 14
Assuming the 705-pound Huygens doesn't splash down in a hydrocarbon lake, "we have good confidence the probe will survive landing," said Jean-Pierre Lebreton, European Space Agency project scientist. "The landing speed is very low and there is a very good probability the probe will survive landing and we have capability to do measurements for half an hour on the surface. During the three-hour measurement phase, the probe will transmit its data to the overflying orbiter."
The original flight plan called for Huygens to enter Titan's atmosphere in late November as Cassini streaked overhead at an altitude of just 746 miles. But engineers were forced to delay Huygens' arrival to January because of an issue with the radio aboard the Cassini mothership that will be used to relay data from Huygens to Earth.
During a post-launch test, engineers discovered the radio receiver could not cope with the Doppler shift in the frequency of the signal coming from Huygens due to Cassini's high relative velocity. Much like the pitch of a siren changes as a police car races past a stationary observer, the frequency of radio waves can shift a significant amount if relative velocities are high enough.
"Originally, the closing speed of Cassini coming up on Huygens, which is for all practical purposes sitting still once it's in the atmosphere, the closing speed was about 5.8 kilometers per second (13,000 mph)," Mitchell said in a recent interview. "We were coming in almost dead overhead and going off to the right at about 1,200 kilometers (746 miles) altitude."
The solution was to minimize the Doppler shift by reducing the relative velocities of the two spacecraft. That was accomplished by changing Cassini's trajectory slightly and delaying Huygens' release to Christmas Eve. During the Jan. 14 descent, Cassini now will be 37,300 miles from Titan and the difference in velocity between the two spacecraft will never be more than 8,500 mph.
"We have pretty solid evidence that's going to work," Mitchell said. "We did some tests where we used the Deep Space Network stations transmitting an S-band signal with telemetry modulated onto the carrier so that from the receiver's point of view on the Cassini spacecraft, it should have simulated the probe quite accurately. We adjusted the frequency, taking into account the motion of everything, so that the frequency of the received signal at the receiver should very closely if not exactly match the frequency that the receiver will see coming from Huygens."
The tests were successful and a potentially crippling design flaw was resolved with no significant loss of science. And the scientific community can't wait to get that data.
Bigger than the planet Mercury, Titan is the only moon in the solar system with a thick atmosphere, one in which hydrocarbons are believed to fall as rain, possibly forming liquid ethane pools on the moon's ultra-cold surface.
Cassini flew past Titan in October, beaming back pictures and radar data that revealed a strange, striated landscape with sharply defined bright and dark regions. Few clouds were present and no large craters were apparent, indicating tectonic, volcanic or depositional processes at work that have resurfaced the moon on a global scale.
But there was no clear evidence of lakes or pools of liquid ethane or similar materials that many scientists believe must be present given the moon's ultra-low temperature, high atmospheric pressure and hydrocarbon chemistry.
In short, Titan's mysteries withstood Cassini's initial scientific assault.
"We've been saying for a long time now that Titan was the largest expanse of unexplored terrain in the solar system," said imaging team leader Carolyn Porco, a leading expert on Saturn's rings. "And what remains hidden under the atmosphere and under the haze, the conditions at its surface, its geological history and so on are, at least in my mind, the solar system's last great mystery."
Huygens should answer many of those questions.
Da Spaceflightnow.com (http://spaceflightnow.com):
Separation Timeline (http://spaceflightnow.com/cassini/041224timeline.html)
Cassini orbiter deploys Titan descent probe
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: December 24, 2004; Updated Dec. 25 @ 12:50 a.m. EST following news briefing
Editor's note... All times in the following story refer to Earth-received time, i.e., when events are confirmed to have happened, not the actual time an event happens at Saturn. One-way light time from Saturn to Earth currently is about 68 minutes.
In a long-awaited milestone, a European-built probe carrying cameras and a suite of scientific instruments was released from NASA's Cassini Saturn orbiter Christmas Eve, setting up a dramatic Jan. 14 plunge into the atmosphere of the ringed planet's mysterious moon Titan.
http://spaceflightnow.com/cassini/images/041224huygenssep.jpg
An artist's concept shows Cassini deploying Huygens. Credit: ESA
Ejected by springs designed to impart a 7-rpm rotation for stability, the Huygens probe was jettisoned from the Cassini mothership around 10:08 p.m. EST. Flight controllers at the Jet Propulsion Laboratory in Pasadena, Calif., verified a clean separation 16 minutes later.
"The short story is the release went absolutely nominally," said Earl Maize, Cassini deputy program manager. "As near as we can tell from all the telemetry we've seen, we've had a perfect separation. The release sequence was executed on board the spacecraft at 7:07 this evening Pacific Standard Time. We were out of radio contact at the time, we expected the release to impart a recoil to the spacecraft and it would take it some minutes to recover radio contact with the Earth. We got back into contact at 7:24 and telemetry soon thereafter verified that all of the events went just as we expected."
Data from Cassini showed the main umbilical between the mothership and Huygens was severed as expected, pyrotechnic devices fired as planned and the orbiter recoiled as engineers predicted it would.
"So we he every expectation that the release was perfectly nominal," Maize told reporters in an early Christmas Day teleconference. "The radio contact was right on the spot and detailed analysis is in progress."
Said Jean-Pierre Lebreton, European Space Agency Huygens project scientist: "I feel very happy. We are now on our way to Titan. It will take 20 days and a big day is in front of us on the 14th of January."
Cassini will attempt to photograph the departing Huygens probe later today to more precisely determine its trajectory.
"We wish to congratulate our European partners as their journey begins and wish them well on their descent to Titan," Robert Mitchell, Cassini program manager at the Jet Propulsion Laboratory in Pasadena, Calif., said earlier in a statement. "We are very excited to see the probe off and to have accomplished this part of our job. Now we're ready to finish our part - receiving and relaying the Huygens data back to Earth."
If all goes well, the flying saucer-shaped Huygens will slam into Titan's hydrocarbon-rich atmosphere around 5:13 a.m. Jan. 14 at a velocity of some 12,400 mph.
Descending through the moon's smoggy atmosphere under parachutes, Huygens will finally reach the surface some two-and-a-half hours after atmospheric entry. Throughout the descent, data from Huygens' instruments will be transmitted to Cassini, flying past the moon nearly 40,000 miles away, stored on digital recorders and later re-transmitted to Earth.
Huygens represents one of the most ambitious space projects ever attempted by the European Space Agency and one that if successful, will reveal a new world to the gaze of eager scientists.
"Today's release is another successful milestone in the Cassini-Huygens odyssey," David Southwood, science director for the European Space Agency, said in a statement. "This was an amicable separation after seven years of living together. Our thanks to our partners at NASA for the lift. Each spacecraft will now continue on its own but we expect they'll keep in touch to complete this amazing mission. Now all our hopes and expectations are focused on getting the first in-situ data from a new world we've been dreaming of exploring for decades."
The stage was set for the probe's release Dec. 16 when flight controllers at JPL carried out orbital trim maneuver No. 8, an 84.9-second main engine firing that put Cassini - and Huygens - on a collision course with Titan.
With Huygens now safely on its way, Cassini's engine will be fired again Dec. 27 to move the mother ship off the current impact trajectory and set up the proper geometry to relay data during the entry probe's descent.
http://spaceflightnow.com/cassini/images/041224huygens.jpg
An artist's concept shows Huygens en route to Titan. Credit: ESA
Huygens begins its final journey into the unknown
25 December 2004
ESA PR 67-2004. The European Space Agency’s Huygens probe was successfully released by NASA’s Cassini orbiter early this morning and is now on a controlled collision course toward Saturn’s largest and most mysterious moon, Titan, where on 14 January it will make a descent through one of the most intriguing atmospheres in the solar system to an unknown surface.
The separation occurred at 02:00 UTC (03:00 CET): A few minutes after separation, Cassini turned back to Earth and relayed back information about the separation. This signal then took 1 hour and 8 minutes to cross the 1.2 billion kilometres separating the Cassini spacecraft and Earth.
“Today’s release is another successful milestone in the Cassini/Huygens odyssey”, said Dr David Southwood, ESA’s Director of Science Programmes. “This was an amicable separation after seven years of living together. Our thanks to our partners at NASA for the lift. Each spacecraft will now continue on its own but we expect they’ll keep in touch to complete this amazing mission. Now all our hopes and expectations are focused on getting the first in-situ data from a new world we’ve been dreaming of exploring for decades”.
Final stage of a seven-year odyssey
The Cassini/Huygens mission, jointly developed by NASA, ESA and the Italian space agency (ASI), began on 15 October 1997, when the composite spacecraft were launched from Cape Canaveral, Florida, atop a Titan 4B/Centaur vehicle. Together, the two probes weighed 5548 kg at launch and became the largest space mission ever sent to the outer planets. To gain sufficient velocity to reach Saturn, they had to conduct four gravity-assist manoeuvres by flying twice by Venus, once by the Earth and once by Jupiter. On 1 July Cassini/Huygens eventually became the first spacecraft to enter an orbit around Saturn.
On 17 December, while on its third orbit around the ringed planet, the Cassini orbiter performed a manoeuvre to enter a controlled collision trajectory towards Titan. As planned, a fine tuning of the trajectory took place on 22 December to place Huygens on its nominal entry trajectrory. While Huygens will remain on this trajectory till it plunges into Titan’s atmosphere on 14 January, the orbiter will perform a deflection manoeuvre on 28 December to avoid crashing onto the moon. Today’s separation was achieved by the firing of pyrotechnic devices. Under the action of push-off springs, ramps and rollers, the probe was released at a relative velocity of about 0.3 m/s with a spin rate of 7 rpm. Telemetry data confirming the separation were collected by NASA’s Deep Space Network stations in Madrid, Spain and Goldstone, California, when the telemetry playback signal from Cassini eventually reached the Earth.
The Huygens probe is now dormant and will remain so for its 20-day coast phase to Titan. Four days before its release, a triply-redundant timer was programmed in order to wake-up the probe’s systems shortly before arrival on Titan.
Exploring Titan’s atmosphere
Huygens is scheduled to enter Titan’s atmosphere at about 09:06 UTC (10:06 CET) on 14 January, entering at a relatively steep angle of 65° and a velocity of about 6 km/s. The target is over the southern hemisphere, on the day side. Protected by an ablative thermal shield, the probe will decelerate to 400 m/s within 3 minutes before it deploys a 2.6 m pilot chute at about 160 km. After 2.5 seconds this chute will pull away the probe’s aft cover and the main parachute, 8.3 m in diameter, will deploy to stabilise the probe. The front shield will then be released and the probe, whose main objective is to study Titan’s atmosphere, will open inlet ports and deploy booms to collect the scientific data. All instruments will have direct access to the atmosphere to conduct detailed in-situ measurements of its structure, dynamics and chemistry. Imagery of the surface along the track will also be acquired. These data will be transmitted directly to the Cassini orbiter, which, at the same time, will be flying over Titan at 60 000 km at closest approach. Earth-based radiotelescopes will also try to detect the signal’s tone directly.
After 15 minutes, at about 120 km, Huygens will release its main parachute and a smaller 3 m drogue chute will take over to allow a deeper plunge through the atmosphere within the lifetime of the probe’s batteries.
The descent will last about 140 minutes before Huygens impacts the surface at about 6 m/s. If the probe survives all this, its extended mission will start, consisting in direct characterisation of Titan’s surface for as long as the batteries can power the instruments and the Cassini orbiter is visible over the horizon at the landing site, i.e. not more than 130 minutes.
At that time, the Cassini orbiter will reorient its main antenna dish toward Earth in order to play back the data collected by Huygens, which will be received by NASA’s 70-m diameter antenna in Canberra, Australia, 67 minutes later. Three playbacks are planned, to ensure that all recorded data are safely transmitted to Earth. Then Cassini will continue its mission exploring Saturn and its moons, which includes multiple additional flybys of Titan in the coming months and years.
A probe deep into space and time
Bigger than Mercury and slightly smaller than Mars, Titan is unique in having a thick hazy nitrogen-rich atmosphere containing carbon-based compounds that could yield important clues about how Earth came to be habitable. The chemical makeup of the atmosphere is thought to be very similar to Earth’s before life began, although colder (-180°C) and so lacking liquid water. The in-situ results from Huygens, combined with global observations from repeated flybys of Titan by the Cassini orbiter, are thus expected to help us understand not only one of the most exotic members of our Solar System but also the evolution of the early Earth's atmosphere and the mechanisms that led to the dawn of life on our planet.
Europe’s main contribution to the Cassini mission, the Huygens probe, was built for ESA by an industrial team led by Alcatel Space. This 320 kg spacecraft is carrying six science instruments to study the atmosphere during its descent. Laboratories and research centres from all ESA member countries, the United States, Poland and Israel have been involved in developing this science payload. The Huygens atmospheric structure instrument package (HASI) will measure temperature and pressure profiles, and characterise winds and turbulences. It will also be able to detect lightning and even to measure the conductivity and permittivity of the surface if the probe survives the impact. The gas chromatograph mass spectrometer (GCMS) will provide fine chemical analysis of the atmosphere and the aerosols collected by the aerosol collector and pyrolyser (ACP). The descent imager/spectral radiometer (DISR) will collect images, spectra and other data on the atmosphere, the radiation budget, cloud structures, aerosols and the surface. The doppler wind experiment (DWE) will provide a zonal wind profile while the surface science package (SSP) will characterise the landing site if Huygens survives the impact.
The Cassini-Huygens mission is a cooperation between NASA, the European Space Agency and ASI, the Italian space agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, is managing the mission for NASA’s Office of Space Science, Washington. JPL designed, developed and assembled the Cassini orbiter.
For further information, please contact:
ESA Media Relations Division
Tel: +33(0)1.53.69.7155
Fax: +33(0)1.53.69.7690
Da Spaceflightnow.com (http://spaceflightnow.com/cassini/041226huygens.html):
Cassini takes picture of departing Huygens probe
CASSINI PHOTO RELEASE
Posted: December 26, 2004
http://spaceflightnow.com/cassini/images/041226huygens.jpg
Credit: NASA/JPL
The Cassini spacecraft snapped this image of the European Space Agency's Huygens probe about 12 hours after its release from the orbiter. The probe successfully detached from Cassini on Dec. 24, 2004, and is on course for its January 14 encounter with Titan.
The Huygens probe will remain dormant until the onboard timer wakes it up just before the probe reaches Titan's upper atmosphere on Jan. 14, 2005. Then it will begin a dramatic plunge through Titan's murky atmosphere, tasting its chemical makeup and composition as it descends to touch down on its surface. The data gathered during this 2-1/2 hour descent will be transmitted from the probe to the Cassini orbiter.
Afterward, Cassini will point its antenna to Earth and relay the data through NASA's Deep Space Network to JPL and on to the European Space Agency's Space Operations Center in Darmstadt, Germany, which serves as the operations center for the Huygens probe mission. From this control center, ESA engineers will be tracking the probe and scientists will be standing by to process the data from the probe's six instruments.
http://spaceflightnow.com/cassini/images/041226close.jpg
Credit: NASA/JPL
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.
Probe travels to surface of Saturn's moon Titan Friday
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: January 12, 2005
KENNEDY SPACE CENTER, Fla. (CBS) - In one of the boldest space missions ever attempted, a small European-built probe will slam into the atmosphere of Saturn's mysterious moon Titan Friday for a two-and-a-half hour parachute descent to its smog-shrouded surface.
http://spaceflightnow.com/cassini/images/050112huygensentry.jpg
An artist's concept shows Huygens nearing Titan. Credit: ESA
Beaming pictures and a torrent of data to NASA's Cassini Saturn orbiter, the flying saucer-shaped Huygens probe will give scientists their first close-up look at one of the largest expanses of unexplored territory in the solar system.
Researchers are hopeful Huygens will answer their most pressing questions: whether hydrocarbons fall like rain and form pools of liquid ethane and similar compounds on the moon's frigid surface; and what erosional or depositional processes are responsible for covering up impact craters and producing a relatively flat, mountain-free surface.
No matter what Huygens actually sees on the surface, scientists expect to gain insights into the workings of a thick, complex atmosphere that in some respects mirrors Earth's shortly after the planet's birth.
"We ought to be able to see a pretty good panorama of the area that the Huygens probe is going to land in," Jonathan Lunine, a planetary scientist at the University of Arizona, said in a recent interview. "Those pictures will continue all the way down to the surface, they'll be interrupted right at the end when the camera switches over to take what are called spectra, which will tell us about the composition of the surface. So we ought to be able to get a pretty good panorama to start with.
"We ought to be able to see whether the probe came down in an area that's mostly craters or other kinds of land forms. We ought to be able to get a hint of whether there might be pools or lakes of liquid in that area. It won't be immediately apparent whether dark places are liquid or solid, but depending on where the probe lands, we might get some direct information on that. And we might see clouds in the sky toward the horizon.
"There may be some detection of lightning," he said, "although there probably isn't a lot of lightning in Titan's atmosphere. And then after impact, or touchdown, if the antennas aren't pointed in a strange direction, we should be able to get some information about the surface. If we're lucky enough to land in liquid, then the probe should be bobbing up and down and there's a tilt meter that will tell us that. And we might be able to get samples of surface material because the probe will still be warm and anything like these liquid hydrocarbons will vaporize and go up into the sample inlets."
Huygens was released from Cassini on Christmas Eve, placed on a collision course with Titan that was set up to ensure the proper atmospheric entry angle. David Southwood, the European Space Agency's science director, thanked NASA for the lift, saying "now all our hopes and expectations are focused on getting the first in situ data from a new world weÕve been dreaming of exploring for decades."
During flybys of Titan in late October and again in December, Cassini's powerful cameras, an imaging radar system and other instruments mapped the surface in unprecedented detail, revealing a relatively flat terrain and unusual, sharply defined features that defied easy explanation.
Only a handful of large crater-like circular structures were apparent and researchers did not see the sort of specular reflections one might expect from sunlight glinting off a liquid surface.
Whether Huygens will detect standing lakes or pools is a major question mark going into Friday's descent. So far, said Torrence Johnson, a Cassini imaging team member at the Jet Propulsion Laboratory in Pasadena, Calif., "we don't have any evidence (for liquids)."
"Just like we don't have any clear evidence of something we know is a crater, there's nothing there that anybody's willing to hang their hat on yet that yes, we absolutely have a liquid surface," he said in a telephone interview Monday.
"What we saw (in the initial Cassini flybys), of course, was a surface that was much stranger than most of us thought we would see," he said. "The real story so far has been the things we didn't see."
Like large craters, hills or mountain ranges and obvious lakes or river-like structures. But that doesn't mean liquids aren't there. Just that Cassini didn't spot them in its initial looks at the moon.
"It's a distinct possibility that I could be the very first scientist to carry out oceanography on an outer planet of the solar system," said John Zarnecki, principal scientist for the Huygens Science Surface Package. "But equally the probe could land with a thud on hard ground or squelch into a morass of extraterrestrial slime - no one knows for sure.
"In any event, the instruments onboard have been designed to handle a range of possibilities," he said in a statement. "Let's just say that, after a seven-year voyage and twenty years of planning, design and build, I will be extremely pleased to land, whatever the surface."
http://spaceflightnow.com/cassini/images/050112atmosphere.jpg
An artist's concept shows Huygens descending on its parachute. Credit: ESA
Huygens, if it survives long enough, should reveal the surface in sharp detail and send back a wealth of data about its thick atmosphere. But even that will not be enough to answer all the questions posed by the scientific community.
"I think we're going to have to wait several flybys, maybe even several years, before we get a really good indication of what's going on," said Carolyn Porco, the Cassini imaging team leader. "What Huygens will do, of course, is give us a very exquisitely detailed view of one place. So their information will (provide) the 'ground truth' for helping us interpret what we see."
Spinning at 7 rpm for stability, Huygens will slam into the atmosphere Friday at an altitude of 789 miles, traveling at some 12,400 mph. A thick carbon composite heat shield will protect the craft from the fierce heat of atmospheric friction - 21,600 degrees Fahrenheit at maximum - which will quickly slow the probe to more benign speeds. Maximum deceleration is expected to be around 16 Gs.
When the velocity has dropped to about 870 mph, Huygens' aft cover will be pulled away by a pilot chute and the spacecraft's 27-foot-wide main parachute will deploy 2.5 seconds later.
The main chute will be jettisoned 15 minutes later and from that point on, Huygens will ride beneath a smaller 9.8-foot-wide parachute. Impact on the surface at some 11 mph is expected about two-and-a-half hours after entry begins. Regardless of how long Huygens might survive on the surface, Cassini will sink below Titan's horizon about 30 minutes after touchdown.
Assuming the 705-pound Huygens doesn't sink in a hydrocarbon lake, "we have good confidence the probe will survive landing," said European Space Agency mission manager Jean-Pierre Lebreton. "The landing speed is very low. We have capability to do measurements for half an hour on the surface."
Here is a detailed timeline of major entry events on Jan. 14 (in EST; all times represent when an event occurs relative to signals received on Earth). Explanations for key events from the European Space Agency's Huygens website; Cassini timeline events provided by the Jet Propulsion Laboratory:
Jan. 14
02:33 AM (-02h40m) - Cassini solid state recorders prepped for support
02:45 AM (-02h28m) - Cassini transition to thruster control for relay
02:55 AM (-02h18m) - Cassini: final recorder configuration for relay
02:57 AM (-02h16m) - Turn on Probe receivers
03:09 AM (-02h04m) - Cassini turns toward Titan
03:21 AM (-01h52m) - Turn to Titan complete
03:24 AM (-01h49m) - Cassini disables X-band downlink
04:51 AM (-00h22m) - Probe turns transmitters on (low power mode)
05:13 AM (-00h00m) - Probe reaches the discernible atmosphere: 789 miles
05:16 AM (+00h03m) - Probe feels maximum deceleration
05:17 AM (+00h04m) - Pilot chute: 106-118 miles altitude; Mach 1.5; The parachute deploys when Huygens detects that it has slowed to 895 mph, at about 112 miles above Titan's surface. The pilot parachute is the probe's smallest, only 8.5 feet in diameter. Its sole purpose is to pull off the probe's rear cover, which protected Huygens from the frictional heat of entry. 2.5 seconds after the pilot parachute is deployed, the rear cover is released and the pilot parachute is pulled away. The main parachute, which is 27.2 feet in diameter, unfurls.
05:18 AM (+00h05m) - At about 99 miles above the surface, the front shield is released. Forty-two seconds after the pilot parachute is deployed, inlet ports are opened up for the Gas Chromatograph Mass Spectrometer and Aerosol Collector Pyrolyser instruments, and booms are extended to expose the Huygens Atmospheric Structure Instruments. The Descent Imager/Spectral Radiometer will capture its first panorama, and it will continue capturing images and spectral data throughout the descent. The Surface Science Package will also be switched on, measuring atmospheric properties.
05:32 AM (+00h19m) - Main parachute separates and drogue parachute deploys: The drogue parachute is 9.8 feet in diameter. At this level in the atmosphere, about 78 miles in altitude, the large main parachute would slow Huygens down so much that the batteries would not last for the entire descent to the surface. The drogue parachute will allow it to descend at the right pace to gather the maximum amount of data.
05:49 AM (+00h36m) - Surface proximity sensor activated: Until this point, all of Huygens's actions have been based on clock timers. At a height of 37 miles, it will be able to detect its own altitude using a pair of radar altimeters, which will be able to measure the exact distance to the surface. The probe will constantly monitor its spin rate and altitude and feed this information to the science instruments. All times after this are approximate.
05:56 AM (+00h43m) - Possible icing effects to Probe (31 miles)
06:57 AM (+01h41m) - Gas Chromatograph Mass Spectrometer begins sampling atmosphere: This is the last of Huygens's instruments to be activated fully. The descent is expected to take 137 minutes in total, plus or minus 15 minutes. Throughout its descent, the spacecraft will continue to spin at a rate of between 1 and 20 rotations per minute, allowing the camera and other instruments to see the entire panorama around the descending spacecraft.
07:19 AM (+02h06m) - Cassini closest approach: 37,282 miles flyby at 12,080 mph, 93 deg phase
07:30 AM (+02h17m) - Descent Imager/Spectral Radiometer lamp turned on: Close to the surface, Huygens's camera instrument will turn on a light. The light is particularly important for the 'Spectral Radiometer' part of the instrument to determine the composition of Titan's surface accurately.
07:34 AM (+02h21m) - Surface touchdown: This time may vary by plus or minus 15 minutes depending on how Titan's atmosphere and winds affect Huygens's parachuting descent. Huygens will hit the surface at a speed of 11.2-13.4 mph. Huygens could land on a hard surface of rock or ice or possibly land on an ethane sea. In either case, Huygens's Surface Science Package is designed to capture every piece of information about the surface that can be determined in the three remaining minutes that Huygens is designed to survive after landing.
09:44 AM (+04h31m) - Cassini stops collecting data; Huygens's landing site drops below Titan's horizon as seen by Cassini and the orbiter stops collecting data. Cassini will listen for Huygens's signal as long as there is the slightest possibility that it can be detected. Once Huygens's landing site disappears below the horizon, there's no more chance of signal, and Huygens's work is finished.
09:46 AM (+04h33m) - Cassini probe data partitions write protected
09:54 AM (+04h41m) - Cassini turns toward Earth
09:57 AM (+04h44m) - Turn to Earth complete
10:06 AM (+04h53m) - Critical sequence ends
10:07 AM (+04h54m) - Post-Probe tracking begins (Canberra)
10:14 AM (+05h01m) - First data sent to Earth: Getting data from Cassini to Earth is now routine, but for the Huygens mission, additional safeguards are put in place to make sure that none of Huygens's data are lost. Giant radio antennas around the world will listen for Cassini as the orbiter relays repeated copies of Huygens data.
10:17 AM (+05h04m) - Probe data replay begins (Canberra: 66,360 bps)
12:57 PM (+07h44m) - End playback of first partition
01:04 PM (+07h51m) - Ascending ring-plane crossing: 18.4 Saturn radii
02:00 PM (+08h47m) - Start tracking at Madrid (142,200 bps)
05:07 PM (+11h54m) - End first full playback of all Probe data
08:29 PM (+15h16m) - Full data set on Earth (likely three hours earlier)
10:35 PM (+17h22m) - Start tracking at Goldstone
Jan. 15
07:07 AM (+01d02h) - Power on of orbiter instruments
08:30 AM (+01d03h) - End nominal playback of Probe data
Cassini braked into orbit around Saturn on July 1 after a seven-year voyage from Earth. The original flight plan called for Huygens to enter Titan's atmosphere in late November as Cassini streaked overhead at an altitude of just 746 miles. But engineers were forced to delay Huygens' arrival to this month because of an issue with the radio aboard the Cassini mothership that will be used to relay data from Huygens to Earth.
During a post-launch test, engineers discovered the radio receiver could not cope with the Doppler shift in the frequency of the signal coming from Huygens due to Cassini's high relative velocity. Much like the pitch of a siren changes as a police car races past a stationary observer, the frequency of radio waves can shift a significant amount if relative velocities are high enough.
"Originally, the closing speed of Cassini coming up on Huygens, which is for all practical purposes sitting still once it's in the atmosphere, the closing speed was about 5.8 kilometers per second (13,000 mph)," Cassini program manager Bob Mitchell said in a recent interview. "And because we were coming in almost dead overhead and going off to the right at about 1,200 kilometers (746 miles) altitude."
The solution was to minimize the Doppler shift by reducing the relative velocities of the two spacecraft. That was accomplished by changing Cassini's trajectory slightly and delaying Huygens' release to Christmas Eve. During the Jan. 14 descent, Cassini now will be 37,300 miles from Titan and the difference in velocity between the two spacecraft will never be more than 8,500 mph.
"We have pretty solid evidence that's going to work," Mitchell said. "We did some tests where we used the Deep Space Network stations transmitting an S-band signal with telemetry modulated onto the carrier so that from the receiver's point of view on the Cassini spacecraft, it should have simulated the probe quite accurately. We adjusted the frequency, taking into account the motion of everything, so that the frequency of the received signal at the receiver should very closely if not exactly match the frequency that the receiver will see coming from Huygens."
The tests were successful and a potentially crippling design flaw was resolved with no significant loss of science. And so, the stage is set for a dramatic voyage of discovery.
"Whatever is there is going to look pretty good, I think," Johnson said. "The probe is spinning as it comes down, sort of a spin-scan imager looking out and down at an angle. Of course, the haze will get less as you go down.
"We had hoped that once it got down to within a hundred kilometers of the surface or something like that we'd start seeing things that looked like pictures out of an airplane window. Based on our data, I think that maybe they will still see a very hazy surface even at longer wavelengths at that type of altitude. Because one of the things that we found is that some of the scattering that's producing this fuzzy appearance on the surface is happening down under 10 kilometers. ... But at some point, we ought to start seeing the surface more clearly. It may be in the last 10 kilometers of descent."
Johnson said he was especially looking forward to finding out "what sort of topography there is. Is it all flat down there? Or are there hints of underlying topography?"
"I would hope we would be able to tell the difference between mantle material that's been covered up by soft aerosols and areas where there might be really flat places with lakes, all of which could be hidden in the data we're seeing now at the resolutions we have."
Whatever Huygens sees, "it could be pretty damn spectacular," Johnson said.
CI SIAMO, IL MOMENTO STA PER ARRIVARE
Tutti i giornali ne parlano , tranne i nostri! :nono:
www.cnn.com
Huygens to plumb secrets of Saturn moon
(CNN) -- The Huygens probe will plunge through the orange clouds of Saturn's moon Titan Friday, offering scientists their first glimpse of the mysterious moon.
"It's going to be the most exotic place we've ever seen," said Candice Hansen, a scientist for the Cassini-Huygens mission. "We've never landed on the surface of an icy satellite. We know from our pictures that there are very different kinds of geological processes."
If all goes well, the saucer-shaped Huygens will enter the thick atmosphere of Titan Friday at about 5:13 a.m. (ET). The data should start trickling in about five hours later.
The Cassini-Huygens mission is an unprecedented $3.3-billion effort between NASA, the European Space Agency and Italy's space program to study Saturn and its 33 known moons. The two vehicles were launched together from Florida in 1997.
"The mission is to explore the entire Saturnian system in considerably greater detail than we have ever been able to do before: the atmosphere, the internal structure, the satellites, the rings, the magnetosphere," said Cassini program manager Bob Mitchell at NASA.
The Huygens probe, about the size of a Volkswagen-Beetle, has been spinning silently toward Titan since it detached from the Cassini spacecraft on December 24. Cassini will remain in orbit around Saturn until at least July 2008.
"[The Cassini-Huygens mission] will probably help answer some of the big questions that NASA has in general about origins and where we came from and where life came from," said Mitchell.
Titan's atmosphere, a murky mix of nitrogen, methane and argon, resembles Earth's before life began more than 3.8 billion years ago. Scientists think the moon may shed light on how life evolved on Earth.
Finding living organisms, however, is a remote possibility. "It is not out of the question, but it is certainly not the first place I would look," said Hansen. "It's really very cold." A lack of sunlight has put Titan into a deep-freeze. Temperatures hover around -292 F (-180 C) making liquid water scarce and hindering chemical reactions needed for organic life.
New discoveries
The mysteries of Saturn, the sixth planet from the sun, have always enticed researchers. Scientists are perplexed why Saturn, a gas-giant composed primarily of hydrogen and helium, releases more energy than it absorbs from faint sunlight. Titan is also the only moon in the solar system to retain a substantial atmosphere, one even thicker than Earth's.
The 703-pound, battery-powered probe will parachute through Titan's clouds of methane and nitrogen for two and a half hours sampling gases and capturing panoramic pictures. Soon afterward, Huygens will reach the surface. However, its landing site is still a matter of conjecture. Scientists say it could be solid, slushy or even a liquid sea of ethane and hydrocarbons.
"Those are the kinds of things that we have theories about, but we really don't have data," said Hansen.
Huygens is expected to hit the upper atmosphere 789 miles (1,270 km) above the moon at a speed of about 13,700 mph (22,000 km/h). A series of three parachutes will slow the craft to just 15 mph (24 km/h). The chutes and special insulation will protect Huygens from temperature swings and violent air currents. Strong winds -- in excess of 311 mph (500 km/h) --will buffet the craft, at times dragging Huygens sideways after its parachute is deployed.
Sensors will deduce wind speed, atmospheric pressure and the conductivity of Titan's air. Methane clouds and possibly hydrocarbon rain can be analyzed by an onboard gas chromatograph. A microphone will listen for thunder.
Three rotating cameras will snap panoramic views of the moon capturing up to 1,100 images. A radar altimeter will map Titan's topography and a special lamp will illuminate the probe's landing spot to help determine the surface composition.
Engineers say they are confident that Huygens and its suite of six sensitive instruments will survive the descent.
"From an engineering standpoint, I'm very confident in a positive outcome," said Shaun Standley, an ESA systems engineer for Huygens at the Jet Propulsion Laboratory in California. "We've been over this again and again for the last three years fine-tuning this."
As the largest and most sophisticated interplanetary vehicle ever launched, according to NASA, Cassini-Huygens has performed well on its 2.2-billion mile (3.5 billion km) journey.
Cassini crossed Saturn's rings without mishap in June 2004 and produced the most revealing photos yet of the rings and massive gas-giant. A problem with the design of an antennae on Cassini almost scrapped Huygens' mission, but engineers altered the spacecrafts' flight plans to resolve the transmission problem.
Now, Huygens is on its own.
Controllers can only that hope years of preparation will pay off. "[Huygens] is on its way, we can't contact it," said Standley. "We can't make any changes of anything that is on board. [It's] just waiting for the right moment."
NASA-ESA CASSINI-HYUGENS MISSION TO SATURN AND TITAN:
- http://saturn.jpl.nasa.gov/home/index.cfm
- http://www.esa.int/esaCP/index.html
TIMELINE:
- http://www.esa.int/esaCP/SEMZGTQ3K3E_index_0.html
NASA TV LIVE COVERAGE:
- http://www.nasa.gov/ram/35037main_portal.ram
HYUGENS POSITION:
http://saturn.jpl.nasa.gov/multimedia/images/moons/images/PIA07229-br402.jpg
Huygens phones home as it descends!!!!
A radio telescope on Earth has detected a faint signal from the descending Huygens spacecraft, confirming the probe is alive, has survived its super-hot entry into the atmosphere and should be carrying out its scientific exploration on the way to the surface of Saturn's moon Titan.
FRIDAY, JANUARY 14, 2005
1033 GMT (5:33 a.m. EST)
SIGNAL FROM HUYGENS! A radio telescope on Earth has detected a faint signal from the descending Huygens spacecraft, confirming the probe is alive, has survived its super-hot entry into the atmosphere and should be carrying out its scientific exploration on the way to the surface of Saturn's moon Titan.
This is just a signal with no actual data included. The data is being relayed to the Cassini orbit and will be played to Earth later today.
Nonetheless, the fact that a signal has been received to verify that Huygens is functioning prompted screams and cheers in mission control.
jumpermax
14-01-2005, 10:56
a leggere ste cose ci si rimane :eek: beccare un segnale del genere da questa distanza....
Originariamente inviato da jumpermax
a leggere ste cose ci si rimane :eek: beccare un segnale del genere da questa distanza....
Hyugens sta scendendo sulla faccia nascosta di Titano, ed evidentemente quella esposta alla Terra, per vengono ricevuti i segnali.
Jumper, perchè non esponi anche a Gio la tua teoria sulle foto in bianco e nero?
jumpermax
14-01-2005, 11:35
Originariamente inviato da gpc
Jumper, perchè non esponi anche a Gio la tua teoria sulle foto in bianco e nero?
ah fetecchione... :D
Secondo gpc non possono fare foto a colori perché contrariamente ai rover marziani la sonda è in movimento. Secondo me invece dipende essenzialmente dal fatto che la luce non è sufficiente per fare foto a colori valide... il problema del movimento si risolve facilmente con 3 sensori separati (come ad esempio fanno le sonde che orbitano attorno a marte) La maggior parte delle foto poi non sono prese nello spettro di luce visibile proprio per questo, la luce non è sufficiente per avere immagini dettagliate. Ma se da una foto all'infrarosso si può ricostruire una forma altrettanto non lo si può fare per i colori...
1115 GMT (6:15 a.m. EST)
Huygens should be continuing its long, parachute-aided fall to the surface of Titan, with the large suite of science instruments operating to study the atmosphere and obtain volumes of pictures. Huygens is doing its work out of view from mission control. Real-time confirmation that the science program is being performed is not available because the craft is sending the information directly to the Cassini orbiter, which itself has turned away from Earth to receive the Huygens data.
Earlier, controllers got a simple tone from Huygens that did announce the craft was at least alive.
A news conference is coming up at 1230 GMT (7:30 a.m. EST). Cassini will resume communications with Earth about three hours later, and the data playback will continue for several hours.
@
PS: ciao gp!
;)
Originariamente inviato da jumpermax
ah fetecchione... :D
Secondo gpc non possono fare foto a colori perché contrariamente ai rover marziani la sonda è in movimento. Secondo me invece dipende essenzialmente dal fatto che la luce non è sufficiente per fare foto a colori valide... il problema del movimento si risolve facilmente con 3 sensori separati (come ad esempio fanno le sonde che orbitano attorno a marte) La maggior parte delle foto poi non sono prese nello spettro di luce visibile proprio per questo, la luce non è sufficiente per avere immagini dettagliate. Ma se da una foto all'infrarosso si può ricostruire una forma altrettanto non lo si può fare per i colori...
Ma guardalo, ma guardalo!
Gli dico di esporre la sua teoria e lui risponde "Secondo gpc..." :nono: Sei proprio diventato un moderatore ormai, non c'è più speranza... :D
Alllllloraaa...
Jumper dice che non si possono fare foto a colori di Saturno perchè c'è troppa poca luce e quindi vengono solo foto in bianco e nero, io invece gli ho spiegato che le foto a colori sono fatte con tre foto in bianco e nero prese con i filtri relativi ai tre colori fondamentali (al che lui ha detto "sì sì, la so anche io quella storiella..." :asd: ) e che, a parte il fatto che di foto a colori ce ne sono eccome, non sempre c'è bisogno di farne tre dello stesso soggetto, sia per una questione di necessità sia per una questione di risparmio di banda.
Inoltre, mentre i rover possono fermarsi e fare i loro mosaici da trecento foto, la sonda si muove e le tre foto, se fatte ad un oggetto troppo vicino, non sarebbero sovrapponibili.
Inoltre, le foto vengono prese a lunghezze d'onda non visibili perchè è a quelle lunghezze d'onda, per esempio, che l'atmosfera di Titano risulta più visibile o che certi fenomeni sono più manifesti, non certamente perchè non c'è abbastanza luce...
Dai Gio, tu che ne pensi? E stai attento, perchè lo sai che discutere con Jumper vuol dire andare avanti finchè uno dei due non è sfinito... (in questo è molto ingegnere, devo riconoscelo... :asd: ) :D :D
PS: Ciao Gio! Hai visto come hanno trattato la missione sulla cometa nell'altro thread? Dicendo che è solo una missione balistica senza nessun senso... :nono:
Lor3nzo76
14-01-2005, 11:52
Originariamente inviato da jumpermax
Ma se da una foto all'infrarosso si può ricostruire una forma altrettanto non lo si può fare per i colori...
In teoria conoscendo la risposta in frequenza, l'assorbimento e l'emissività dei vari materiali si potrebbe ricostruire il colore a partire da un immagine all'infrarosso, ma prevede che di ogni matriale sostanza o miscela si conosca esattamente il diagramma potere emissivo - frequenza, e nel caso di miscele anche la composizione approssimata.
Così però si va nei matti e si otterrebbe comunque un risultato approssimato, visto che sarebbe impossibile conoscere tutte le variabili con uno scarto decente.
Lore
Originariamente inviato da jumpermax
ah fetecchione... :D
Secondo gpc non possono fare foto a colori perché contrariamente ai rover marziani la sonda è in movimento. Secondo me invece dipende essenzialmente dal fatto che la luce non è sufficiente per fare foto a colori valide... il problema del movimento si risolve facilmente con 3 sensori separati (come ad esempio fanno le sonde che orbitano attorno a marte) La maggior parte delle foto poi non sono prese nello spettro di luce visibile proprio per questo, la luce non è sufficiente per avere immagini dettagliate. Ma se da una foto all'infrarosso si può ricostruire una forma altrettanto non lo si può fare per i colori...
Questa volta ha ragione gp, infatti le immagini sono fatte in bianco e nero o con i singoli filtri, per comporre un immagine a colori occorre sovrappore le immagini con i tre filtri relativi ai colori fondamentali.
Per il resto, il tutto viene spiegato in questa discussione di SDC:
http://uplink.space.com/showflat.php?Cat=&Board=missions&Number=64022&page=25&view=collapsed&sb=5&o=0&fpart=
Originariamente inviato da GioFX
Questa volta ha ragione gp
YYYAAAAAAAAAAAAHHHHHH :yeah:
Grazie Gio, lo so che queste frasi ti costano almeno cinque anni di vita l'una... :D :D
Originariamente inviato da gpc
YYYAAAAAAAAAAAAHHHHHH :yeah:
Grazie Gio, lo so che queste frasi ti costano almeno cinque anni di vita l'una... :D :D
meno male, non l'ho dovuto dire io... :fiufiu: :Prrr:
jumpermax
14-01-2005, 12:26
Originariamente inviato da GioFX
Questa volta ha ragione gp, infatti le immagini sono fatte in bianco e nero o con i singoli filtri, per comporre un immagine a colori occorre sovrappore le immagini con i tre filtri relativi ai colori fondamentali.
Per il resto, il tutto viene spiegato in questa discussione di SDC:
http://uplink.space.com/showflat.php?Cat=&Board=missions&Number=64022&page=25&view=collapsed&sb=5&o=0&fpart=
questo lo so, tant'è che ai tempi delle foto marziane me le ero pure ricostruite per conto mio... gpc come al solito ha riportato la sua versione del mio pensiero che ovviamente non è quello che avevo detto :D io gli avevo semplicemente fatto notare che la mancanza di luce rende quasi impossibile la realizzazione di foto a colori, del resto basta guardare cosa Cassini ha fotografato quando è passata vicino a Giove
http://saturn.jpl.nasa.gov/multimedia/images/mission/PIA04866-br500.jpg
e cosa invece abbia preso di saturno
http://saturn.jpl.nasa.gov/multimedia/images/saturn/PIA06060-br500.jpg
per capire come la mancanza di luce renda quasi impossibile una buona foto a colori. Stavolta gpc ha torto... :D
ma sono immagini colorate con l'uso dei filtri.
Originariamente inviato da jumpermax
gpc come al solito ha riportato la sua versione del mio pensiero che ovviamente non è quello che avevo detto :D
Ma sei falso come Ce... ehm, come Giuda! :O :D
Guarda che posto i log di icq, eh! :D
Stavolta gpc ha torto... :D
Miiii nemmeno davanti all'evidenza cede... :cry: :D
Originariamente inviato da GioFX
ma sono immagini colorate con l'uso dei filtri.
Vediamo se tu riesci a convincerlo che se non ci fosse luce per le foto a colori non ce ne sarebbe nemmeno per quelle in bianco e nero, dato che le foto a colori vengono fatte con quelle in bianco e nero...
jumpermax
14-01-2005, 12:37
Originariamente inviato da GioFX
ma sono immagini colorate con l'uso dei filtri.
i filtri non possono ricostruire un'informazione che non c'è... o l'immagine di partenza ha una buona definizione cromatica oppure non c'è verso di ricostruirla in seguito... al massimo la si può ritoccare ma sarebbe una rielaborazione artistica. Senza luce sufficiente si possono fare solo foto in bianco e nero... oppure con falsi colori, ma è un altra questione.
ma jumper, si può fotografare qualsiasi corpo celeste del sistema solare, e oltre, con la luce emessa dal sole... non è questione di quanto siano illuminati i pianeti, anche con un centesimo della luce solare che c'è sulla terra, come è su Titano, esiste luce sufficiente per fare foto nel visibile, sia in bianco e nero, che con i filtri CCD.
jumpermax
14-01-2005, 12:44
Originariamente inviato da gpc
Vediamo se tu riesci a convincerlo che se non ci fosse luce per le foto a colori non ce ne sarebbe nemmeno per quelle in bianco e nero, dato che le foto a colori vengono fatte con quelle in bianco e nero...
Stai ragionando con gli occhi e non con la testa. Per poter cogliere i colori devi avere una determinato spettro, se io voglio capire se un oggetto è rosso o verde ho bisogno di vedere come viene riflessa la luce visibile. Per capirne la forma invece non mi serve tutto ciò una qualsiasi lunghezza d'onda in cui il corpo emetta radiazioni mi sta bene.
Originariamente inviato da jumpermax
i filtri non possono ricostruire un'informazione che non c'è... o l'immagine di partenza ha una buona definizione cromatica oppure non c'è verso di ricostruirla in seguito... al massimo la si può ritoccare ma sarebbe una rielaborazione artistica. Senza luce sufficiente si possono fare solo foto in bianco e nero... oppure con falsi colori, ma è un altra questione.
Jumper ma che stai dicendo? Io faccio una foto con il filtro rosso, verde e blu e ottengo tre immagini in bianco e nero; le metto assieme e ricavo quella a colori. Che caspita c'entra la risoluzione cromatica? Secondo me non hai ben chiaro come funziona il tutto...
jumpermax
14-01-2005, 12:45
Originariamente inviato da GioFX
ma jumper, si può fotografare qualsiasi corpo celeste del sistema solare, e oltre, con la luce emessa dal sole... non è questione di quanto siano illuminati i pianeti, anche con un centesimo della luce solare che c'è sulla terra, come è su Titano, esiste luce sufficiente per fare foto nel visibile, sia in bianco e nero, che con i filtri CCD.
Se fosse come dici tu le immagini provenienti da titano e da saturno sarebbero qualitativamente paragonabili a quelle di giove. Non è così invece, poi è chiaro aumentando il guadagno ed il tempo di esposizione la foto viene, ma mossa e molto rumorosa.
Originariamente inviato da jumpermax
Stai ragionando con gli occhi e non con la testa. Per poter cogliere i colori devi avere una determinato spettro, se io voglio capire se un oggetto è rosso o verde ho bisogno di vedere come viene riflessa la luce visibile. Per capirne la forma invece non mi serve tutto ciò una qualsiasi lunghezza d'onda in cui il corpo emetta radiazioni mi sta bene.
Sì ma non c'entra nulla. Le foto a colori di Saturno ci sono eccome, questo fatto nudo e crudo dovrebbe bastare a farti capire che ti stai sbagliando...
jumpermax
14-01-2005, 12:47
Originariamente inviato da gpc
Jumper ma che stai dicendo? Io faccio una foto con il filtro rosso, verde e blu e ottengo tre immagini in bianco e nero; le metto assieme e ricavo quella a colori. Che caspita c'entra la risoluzione cromatica? Secondo me non hai ben chiaro come funziona il tutto...
Ti manca un passaggio, per fare la foto hai poi bisogno di una quantità sufficiente di luce nei vari filtri. Se il corpo non ne emette abbastanza ti scordi di poter fare foto... ;) cosa invece che puoi fare in bianco e nero perché non hai bisogno di usare la luce visibile.
Originariamente inviato da jumpermax
Se fosse come dici tu le immagini provenienti da titano e da saturno sarebbero qualitativamente paragonabili a quelle di giove. Non è così invece, poi è chiaro aumentando il guadagno ed il tempo di esposizione la foto viene, ma mossa e molto rumorosa.
Macchè mossa e rumorosa... La sonda non è passata vicino a Giove come è passata vicino a Saturno e Titano, quindi è ovvio che vedi le foto di Giove più "nitide", semplicemente perchè sono fatte più da lontano e mostrano meno particolari!
Secondo te cosa c'è tra Giove e Saturno? Una tenda? Degli scuretti che bloccano il sole? Hanno messo una tapparella? :D
jumpermax
14-01-2005, 12:49
Originariamente inviato da gpc
Sì ma non c'entra nulla. Le foto a colori di Saturno ci sono eccome, questo fatto nudo e crudo dovrebbe bastare a farti capire che ti stai sbagliando...
si bravo, ne ho postata una per confronto qualche riga sopra... ti sembra che la qualità sia la stessa di quella di giove? Hmm quale potrebbe essere la differenza?
a)saturno è più brutto
b)risparmiano sulla pellicola
c)c'è troppa poca luce...
:D
Originariamente inviato da jumpermax
Ti manca un passaggio, per fare la foto hai poi bisogno di una quantità sufficiente di luce nei vari filtri. Se il corpo non ne emette abbastanza ti scordi di poter fare foto... ;) cosa invece che puoi fare in bianco e nero perché non hai bisogno di usare la luce visibile.
Jumper, anche a te manca un passaggio. Ci sono foto a colori fino di Nettuno, mi spieghi con cosa le avrebbero fatte se fosse vero quello che dici tu? Con la sfera di cristallo?
Inoltre, ti ribadisco il concetto, una foto a colori è formata da tre foto in bianco e nero: se non si potessero fare foto a colori, non potresti fare nemmeno foto in bianco e nero.
jumpermax
14-01-2005, 12:51
Originariamente inviato da gpc
Macchè mossa e rumorosa... La sonda non è passata vicino a Giove come è passata vicino a Saturno e Titano, quindi è ovvio che vedi le foto di Giove più "nitide", semplicemente perchè sono fatte più da lontano e mostrano meno particolari!
Secondo te cosa c'è tra Giove e Saturno? Una tenda? Degli scuretti che bloccano il sole? Hanno messo una tapparella? :D
non ragioni in 3D... prova a fare una foto sotto un lampione o a 50 metri.... ;)
Originariamente inviato da jumpermax
si bravo, ne ho postata una per confronto qualche riga sopra... ti sembra che la qualità sia la stessa di quella di giove? Hmm quale potrebbe essere la differenza?
a)saturno è più brutto
b)risparmiano sulla pellicola
c)c'è troppa poca luce...
:D
Mah, sembrano i discorsi che facevi sul patrimonio artistico... :nono:
Su cosa baseresti, di grazia, il tuo confronto tra le due foto?
Originariamente inviato da jumpermax
non ragioni in 3D... prova a fare una foto sotto un lampione o a 50 metri.... ;)
Vabbè, per quel che mi riguarda ci rinuncio, se non accetti nemmeno l'evidenza non so che farci, problema tuo.
Gio, vedi se tu riesci ad essere ascoltato...
jumpermax
14-01-2005, 13:59
Originariamente inviato da gpc
Jumper, anche a te manca un passaggio. Ci sono foto a colori fino di Nettuno, mi spieghi con cosa le avrebbero fatte se fosse vero quello che dici tu? Con la sfera di cristallo?
Inoltre, ti ribadisco il concetto, una foto a colori è formata da tre foto in bianco e nero: se non si potessero fare foto a colori, non potresti fare nemmeno foto in bianco e nero.
ti dimostro dove la tua logica è sbagliata
a) una foto a colori è formata da tre foto in b/n
questo vuol dire
colore->b/n
b)se non si potessero fare foto a colore non potresti fare foto in b/n
questo vuol dire
not colore->not b/n che non puoi desumere dall'affermazione precedente
infatti il massimo che puoi desumere è
not b/n ->not colore
Perchè si possono comunque fare foto in bianco e nero ? Perché il bianco e nero non fa riferimento ad una specifica lunghezza d'onda ma è solo una funzione di intensità del segnale. Mentre una foto a colori insomma ci mostra una composizione di intensità di onde di lunghezza diverse (specifiche però) il bianco e nero da solo un'intensità generica. Per avere immagini da saturno paragonabili a quelle di giove dovresti avere un obbiettivo molto più sensibile alla luce... saturno dista dal sole quasi il doppio di giove. Questo vuol dire che riceve un quarto della luce circa... ergo che ci vuole un sensore 4 volte più grande.
1300 GMT (8:00 a.m. EST)
A huge radio telescope at Green Bank, West Virginia, was able to detect and lock onto a faint carrier signal from the Huygens Titan probe for more than two hours this morning, confirming the spacecraft's continued descent through the moon's atmosphere following a high-speed entry.
A second radio telescope now has picked up the signal as well and Europoean Space Agency project scientist Jean-Pierre Lebreton said engineers were even able to confirm at least one of the probe's six on-board instruments had activated as planned.
1332 GMT (8:32 a.m. EST)
Mission controllers say the tone from Huygens is still being received! The craft appears to have landed around 1245 or 1246 GMT (7:45 or 7:46 a.m. EST) on Titan and continues to operate from the moon's surface.
1403 GMT (9:03 a.m. EST)
Huygens remains alive and sending its beeping signal from the surface -- more than an hour after controllers calculate it landed. The relay of science data to Cassini concludes later this hour as the orbiter goes over the horizon from the landing site.
The first science information is expected on Earth about two hours from now.
Huygens carrier signal 'solid' for more than two hours
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: January 14, 2005
A huge radio telescope at Green Bank, West Virginia, was able to detect and lock onto a faint carrier signal from the Huygens Titan probe for more than two hours this morning, confirming the spacecraft's continued descent through the moon's atmosphere following a high-speed entry around 5:13 a.m. EST (1013 GMT).
A second radio telescope now has picked up the signal as well and Europoean Space Agency project scientist Jean-Pierre Lebreton said engineers were even able to confirm at least one of the probe's six on-board instruments had activated as planned.
Touchdown on Titan's surface was expected around 7:34 a.m.
But detection of a carrier - a feat equivalent to picking up a cell phone call from 751 million miles away - only means the spacecraft was alive and that it survived the rigors of atmospheric entry. Confirmation that actual science data was collected won't be available until 11:15 a.m. EST, after NASA's Cassini spacecraft relays recorded data to Earth.
"We've got a long way to go," said ESA science director David Southwood. "As far as i'm concerned,the baby is out of the womb, but we've yet to count the fingers and toes, so we've still got a long way to go. But it's a major step, a major engineering step. You can probably detect a certain relief on my face. That's real. But there's still a long way to go before the full baby is revealed."
NASA science chief Al Diaz said detection of the carrier signal "means that probably one of the most difficult entry activities ever done has just been accomplished successfully."
Originariamente inviato da jumpermax
ti dimostro dove la tua logica è sbagliata
a) una foto a colori è formata da tre foto in b/n
questo vuol dire
colore->b/n
b)se non si potessero fare foto a colore non potresti fare foto in b/n
questo vuol dire
not colore->not b/n che non puoi desumere dall'affermazione precedente
infatti il massimo che puoi desumere è
not b/n ->not colore
Perchè si possono comunque fare foto in bianco e nero ? Perché il bianco e nero non fa riferimento ad una specifica lunghezza d'onda ma è solo una funzione di intensità del segnale. Mentre una foto a colori insomma ci mostra una composizione di intensità di onde di lunghezza diverse (specifiche però) il bianco e nero da solo un'intensità generica. Per avere immagini da saturno paragonabili a quelle di giove dovresti avere un obbiettivo molto più sensibile alla luce... saturno dista dal sole quasi il doppio di giove. Questo vuol dire che riceve un quarto della luce circa... ergo che ci vuole un sensore 4 volte più grande.
Ci riprovo...
Jumper, il tuo ragionamento è sbagliato in partenza: le foto in B/N che vedi non sono foto in B/N propriamente dette, sono foto relative ad un solo colore!!!!
jumpermax
14-01-2005, 14:36
Originariamente inviato da gpc
Ci riprovo...
Jumper, il tuo ragionamento è sbagliato in partenza: le foto in B/N che vedi non sono foto in B/N propriamente dette, sono foto relative ad un solo colore!!!!
questo mi sembrava chiaro fin dall'inizio... :D
Infatti, ha ragione gp... :)
non te la prendere jumpetto. :D
Frank1962
14-01-2005, 14:46
....ma la sonda quando comincierà a mandare le prime foto/dati ?
jumpermax
14-01-2005, 14:46
Originariamente inviato da GioFX
Infatti, ha ragione gp... :)
non te la prendere jumpetto. :D
perchè dovrei prendermela se voi siete in torto? Prima o poi vedrete la luce... :D
Originariamente inviato da jumpermax
perchè dovrei prendermela se voi siete in torto? Prima o poi vedrete la luce... :D
Quando inauguri il tempio dedicato a te stesso ci chiami, vero? :sofico:
il ragionamento di jumpermax è così chiaro... perchè vi ostinate a contraddirlo... :O
è come se volessimo cercare di rendere a colori quello che guardiamo attraverso i raggi infrarossi...
ci siamo + o - jump?
1445 GMT (9:45 a.m. EST)
Here is the press statement issued by the European Space Agency:
"The Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, USA, a part of the global network of radio telescopes involved in tracking the Huygens Titan probe, has detected the probe's 'carrier' (tone) signal.
"The detection occurred between 11:20 and 11:25 CET (5:20-5:25 a.m. EST), shortly after the probe began its parachute descent through Titan's atmosphere. The extremely feeble signal was first picked up by the Radio Science Receiver supplied by the NASA Jet Propulsion Laboratory. This signal is an important indication that the Huygens probe is 'alive'. However, it does not contain yet any substance; the latter is expected to come a few hours later via the Cassini spacecraft.
"What the Green Bank radio telescope has detected is only a Œcarrier¹ signal. It indicates that the back cover of Huygens must have been ejected, the main parachute must have been deployed and that the probe has begun to transmit, in other words, the probe is Œalive¹. This, however, still does not mean that any data have been acquired, nor that they have been received by Cassini. The carrier signal is sent continuously throughout the descent and as such does not contain any scientific data. It is similar to the tone signal heard in a telephone handset once the latter is picked up.
"Only after having received the data packets at ESOC will it be possible to say with certainty whether data were properly acquired. The first data set from Cassini will reach ESOC in the afternoon. Additional downlinks will follow throughout the evening and night for redundancy.
"Further analysis of the signals will be conducted using other three independent data acquisition systems at the Green Bank Telescope. In addition to the GBT, sixteen other radio telescopes in Australia, China, Japan and the USA are involved in tracking the Huygens probe.
"The ultimate goal of the tracking experiment is to reconstruct the probe's descent trajectory with an unprecedented accuracy of the order of one kilometre. The measurements will be conducted using Very Long Baseline Interferometry (VLBI) and Doppler tracking techniques. This would enable studies of the dynamics of Titan's atmosphere, which is considered to be a 'frozen' copy of that of the early Earth.
"The VLBI component of the tracking experiment is coordinated by the Joint Institute for VLBI in Europe (JIVE) and ESA; the Doppler measurements are conducted by the Jet Propulsion Laboratory."
1501 GMT (10:01 a.m. EST)
A tone is still being emitted from Huygens and detected by radio telescopes on Earth, now more than two hours after landing. Meanwhile, Cassini has turned away from Cassini to re-point its communications antenna for relay of data to Earth.
1510 GMT (10:10 a.m. EST)
"This is clearly an engineering success and we know the probe has been successfully entering the atmosphere, has been descending on the parachute to the surface," said Jean-Pierre Lebreton, ESA's Huygens project scientist.
"But at this moment we cannot say more. I mean, we have not seen the data. What we have seen is a tone, a signal, which was indicating that the probe was transmitting but we have not seen any real data yet. So I would like to wait a bit more to say whether we have a successful mission or not."
The first Huygens data via the Cassini telemetry playback is expected in about an hour.
jumpermax
14-01-2005, 15:27
Originariamente inviato da AMDman
il ragionamento di jumpermax è così chiaro... perchè vi ostinate a contraddirlo... :O
è come se volessimo cercare di rendere a colori quello che guardiamo attraverso i raggi infrarossi...
ci siamo + o - jump?
bingo.... ;)
1526 GMT (10:26 a.m. EST)
The communications link between Cassini and Earth has been established.
1530 GMT (10:30 a.m. EST)
Scientists have another 40 minutes of suspense before the first Huygens data arrives on Earth, which will confirm probe's transmissions to Cassini and recording aboard the orbiter has worked.
Originariamente inviato da AMDman
il ragionamento di jumpermax è così chiaro... perchè vi ostinate a contraddirlo... :O
è come se volessimo cercare di rendere a colori quello che guardiamo attraverso i raggi infrarossi...
ci siamo + o - jump?
Ah beh allora Jumper non ha capito anche altre cose oltre a quelle già elencate :D
Per esempio non ha capito che gli infrarossi sono UN filtro, ci sono i filtri dei colori visibili, gli ultravioletti, etc, e ovviamente quando fanno le foto a colori usano l'RGB, quando vogliono osservare fenomeni meglio visibili in altre lunghezze d'onda usano altri filtri...
Insomma, non c'azzecca proprio per nulla il discorso di Jumper, ma lui s'è convinto e manco se venisse il padreterno a dirglielo cambierebbe idea :D
jumpermax
14-01-2005, 15:53
Originariamente inviato da gpc
Ah beh allora Jumper non ha capito anche altre cose oltre a quelle già elencate :D
Per esempio non ha capito che gli infrarossi sono UN filtro, ci sono i filtri dei colori visibili, gli ultravioletti, etc, e ovviamente quando fanno le foto a colori usano l'RGB, quando vogliono osservare fenomeni meglio visibili in altre lunghezze d'onda usano altri filtri...
Insomma, non c'azzecca proprio per nulla il discorso di Jumper, ma lui s'è convinto e manco se venisse il padreterno a dirglielo cambierebbe idea :D
beh finchè continui a tirare fuori concetti che non contraddicono quanto ho detto difficile che mi convinci... :D
spinbird
14-01-2005, 15:53
ha ragione gpc...anche se purtroppo è del vecchio ordinamento:p
Originariamente inviato da jumpermax
beh finchè continui a tirare fuori concetti che non contraddicono quanto ho detto difficile che mi convinci... :D
Jumper, allora non leggi: ti ho (ti abbiamo, perchè se vedi adesso siamo in tre a sostenere la stessa cosa) detto che quello che dici tu non è vero, che il ragionamento che fai è sbagliato, che le conclusioni che trai non hanno fondamento. Di più, non so che fare :D Se vuoi sentire un parere dal padreterno, poi fammi sapere che ti ha detto... :D
jumpermax
14-01-2005, 16:04
Originariamente inviato da gpc
Jumper, allora non leggi: ti ho (ti abbiamo, perchè se vedi adesso siamo in tre a sostenere la stessa cosa) detto che quello che dici tu non è vero, che il ragionamento che fai è sbagliato, che le conclusioni che trai non hanno fondamento. Di più, non so che fare :D Se vuoi sentire un parere dal padreterno, poi fammi sapere che ti ha detto... :D
Da quando in qua queste cose si decidono per alzata di mano? :D Scusate ma davvero siete convinti che se saturno fosse nelle condizioni di luminosità di giove le foto verrebbero in quel modo? :D
1605 GMT (11:05 a.m. EST)
Scientists, engineers and senior officials have gathered in a large crowd within the European mission control center. Everyone is nervously awaiting the first bits of data from Huygens.
Vabbè, io ci rinuncio per davvero. Tanto se non vuoi ascoltare è inutile stare a parlare.
NASA TV - Live Coverage (http://www.nasa.gov/ram/35037main_portal.ram)
Originariamente inviato da GioFX
NASA TV - Live Coverage (rstp://www.nasa.gov/ram/35037main_portal.ram)
Non me lo apre! Cos'è "rstp"??
Originariamente inviato da gpc
Non me lo apre! Cos'è "rstp"??
Riprova adesso, ho cambiato in http!
1619 GMT (11:19 a.m. EST)
The Huygens data is being received! Applause has erupted in the German control room after the tense and anxious wait. It will take some time to begin examining the information. The first pictures from Huygens could be released later today.
1630 GMT (11:30 a.m. EST)
We're awaiting the start of a planned news conference. The top science officials from ESA and NASA were in the room and then left.
1635 GMT (11:35 a.m. EST)
The news briefing has begun.
"We have scientific success," the ESA director general reports.
"We are the first visitors of Titan."
Ah ecco, adesso che parla in tedesco è più chiaro... :fagiano:
Originariamente inviato da gpc
Ah ecco, adesso che parla in tedesco è più chiaro... :fagiano:
perchè prima tu capivi qualcosa? :D :sofico: :D
1645 GMT (11:45 a.m. EST)
Here is a press statement from Alcatel:
"The Huygens space probe has arrived on Titan. The probe was built by prime contractor Alcatel Space, a subsidiary of Alcatel, leading a consortium of 40 companies and laboratories. Alcatel Space is the first European company to have met the challenge of constructing a spacecraft designed to resist such draconian conditions. This is the first time that a man-made object has landed on the moon of a planet so far away in our solar system. This is also the first time that an European probe has successfully landed on another part of the solar system.
"The interplanetary voyage of Cassini/Huygens took seven years, and made use of successive gravity boosts from Venus (twice), the Earth and Jupiter. Huygens had to stand up to temperatures of 212 deg F near Venus, and made a blind crossing of the asteroid belt between Mars and Jupiter, then the rings of Saturn. However, the technical challenge reached its zenith during the descent towards Titan, which lasted nearly three weeks after the separation from the Cassini mother-craft on December 25. Following aerodynamic braking in the upper atmosphere, then deployment of three parachutes to control the descent, the probe landed on the surface of Titan. Huygens is a veritable flying lab, featuring six advanced instruments to carry out all measurements expected by the scientific community.
"Meanwhile, Cassini is in orbit around Saturn for its own observation mission, while relaying data from Huygens back to Earth.
"The Cassini/Huygens programs was an unprecedented technical challenge, tackling aspects that had never before been studied:
- Major restrictions on mass and energy, given the distance to be traveled and the complex trajectory needed to reach Saturn via gravity boosts form Venus, Earth and Jupiter.
- Completely autonomous operation.
- High-precision Cassini/Huygens separation maneuvers.
Thermal shield adapted to an entry into Titan's atmosphere.
- Parachute deployment at supersonic speed.
- Sufficient robustness to stand up to unknown elements, especially atmospheric (furthermore, scientists have continuously changed their models since the knowledge of Titan was increased, which required an important effort to ensure successful entry).
"We are especially proud of this huge success by our customer ESA, in partnership with NASA and ASI," said Pascale Sourisse, Chairman and CEO of Alcatel Space. "Not only is it a world first in exploration of the universe, it also marks a major step forward in better understanding the origins of life. With the Huygens mission now accomplished, we want to reaffirm our unyielding commitment to carrying out the most demanding programs for interplanetary exploration and observation of the universe, alongside European scientists and space agencies. We hope that this mission will pave the way to other adventures that prove to be just as exciting, both scientifically and technologically."
1655 GMT (11:55 a.m. EST)
ESA says data is being received normally on the Channel B telemetry steam. However, the Channel A has a question mark surrounding it.
1658 GMT (11:58 a.m. EST)
The probe went through the entry phase, the parachute deployment was within 15 seconds of the planned time and onboard accelerometer data worked normally, officials are saying at the news conference. The playback of data continues.
1701 GMT (12:01 p.m. EST)
The temperature inside the probe was 25 degrees C as it was descending through 50 km altitude, the ongoing data review shows.
1706 GMT (12:06 p.m. EST)
Engineers says the Channel A and Channel B data paths from Huygens are redundant with the exception that Channel A is needed for the Doppler wind experiment with the Cassini orbiter. The Channel A telemetry stream isn't working as expected, but Channel B appears normal, ESA says.
Ma l'ambiente esterno come si suppone che sia ?
Frank1962
14-01-2005, 17:23
Originariamente inviato da cionci
Ma l'ambiente esterno come si suppone che sia ?
.....ma sopratutto, sta sonda ha mandato qualche immagine?
:confused: :muro:
ma li leggete mai i post? :O
e scusate, pensate poi che sia istantaneo ricostruire immagini partendo da un flusso di dati a bassissimo transfer rate?
:mbe: :mbe:
1722 GMT (12:22 p.m. EST)
NASA's Cassini Saturn orbiter began downlinking science data from the European Space Agency's Huygens probe at 11:19 a.m. EST (1619 GMT), confirming the spacecraft not only survived its high-speed plunge into the atmosphere of Saturn's moon, Titan, but that its instruments worked to remotely explore one of the strangest worlds in the solar system.
Frank1962
14-01-2005, 17:32
Originariamente inviato da GioFX
ma li leggete mai i post? :O
e scusate, pensate poi che sia istantaneo ricostruire immagini partendo da un flusso di dati a bassissimo transfer rate? :muro: :O
parli della pappardella anglosassone che posti a tonnellate ogni volta che c'è un avvenimento di questo tipo!? :rolleyes: :D :D :D
ps: il mio eng non che sia il massimo....mea culpa :cry:
B]1955 GMT (2:55 p.m. EST)[/B]
The first picture from the descending Huygens probe showing the Titan surface has been revealed in mission control!
1956 GMT (2:56 p.m. EST)
The first image shows what appear to be drainage channels flowing to a possible shoreline, the camera's scientist says. The pictures are raw and unprocessed.
http://www.spaceflightnow.com/cassini/images/050114huygens1.jpg
This is the first picture from Huygens released by ESA. It was taken at an altitude of 16 km as Huygens made its descent. Credit: ESA/NASA TV
Frank1962
14-01-2005, 20:37
http://www.esa.int/images/landing01_L.jpg
...la prima immagine al mondo della superfice di titano! ;)
Matrixbob
14-01-2005, 21:23
Originariamente inviato da Frank1962
http://www.esa.int/images/landing01_L.jpg
...la prima immagine al mondo della superfice di titano! ;)
Viva!!!:cool:
... ma come so che è autentica e non il cortile di casa tua?!:mbe:
Frank1962
14-01-2005, 21:27
Originariamente inviato da Matrixbob
Viva!!!:cool:
... ma come so che è autentica e non il cortile di casa tua?!:mbe:
potrebbe essere il cortile di quelli dell'esa....
http://www.esa.int/SPECIALS/Cassini-Huygens/index.html
:D
Veramente è questa la prima immagine...
http://www.spaceflightnow.com/cassini/images/050114huygens1.jpg
:O
Matrixbob
14-01-2005, 22:29
... mah li non ha ancora attitanato ehm atterrato :D
Ma non doveva essere liquida la superficie ? Sembra marte :confused:
bob_marley_23
15-01-2005, 10:28
ma è vero che la sonda atterrata nn è sopravvissuta + di 3 min?
cioè dovremo accontentarci di qualke fotarella e basta?....:(
jumpermax
15-01-2005, 11:09
Originariamente inviato da GioFX
1655 GMT (11:55 a.m. EST)
ESA says data is being received normally on the Channel B telemetry steam. However, the Channel A has a question mark surrounding it.
1658 GMT (11:58 a.m. EST)
The probe went through the entry phase, the parachute deployment was within 15 seconds of the planned time and onboard accelerometer data worked normally, officials are saying at the news conference. The playback of data continues.
1701 GMT (12:01 p.m. EST)
The temperature inside the probe was 25 degrees C as it was descending through 50 km altitude, the ongoing data review shows.
25 ° celsius? :eek:
jumpermax
15-01-2005, 11:14
ok qualche news e qualche foto nuova
http://www.esa.int/esaCP/SEMTKR71Y3E_index_1.html
http://esamultimedia.esa.int/images/cassini_huygens/huygens_land/Picture2.jpg
http://www.esa.int/images/Picture7_L.jpg
Matrixbob
15-01-2005, 11:30
Originariamente inviato da bob_marley_23
ma è vero che la sonda atterrata nn è sopravvissuta + di 3 min?
cioè dovremo accontentarci di qualke fotarella e basta?....:(
Ma vah doveva durare almeno 2 ore e così mi pare abbia fatto.
Originariamente inviato da bob_marley_23
ma è vero che la sonda atterrata nn è sopravvissuta + di 3 min?
cioè dovremo accontentarci di qualke fotarella e basta?....:(
Il popolo si deve accontentare sempre solo di qualche fotarella, gli scienziati di tutti i dati raccolti.
Inoltre la sonda è durata più delle due ore di tempo disponibili per il link con la sonda...
Originariamente inviato da Matrixbob
Ma vah doveva durare almeno 2 ore e così mi pare abbia fatto.
No, se non ricordo male doveva durare pochi minuti dopo l'atterraggio e invece ha sforato perfino il tempo disponibile per la comunicazione con Cassini...
jumpermax
15-01-2005, 11:37
Originariamente inviato da gpc
No, se non ricordo male doveva durare pochi minuti dopo l'atterraggio e invece ha sforato perfino il tempo disponibile per la comunicazione con Cassini...
azz peccato... non avrà più finestre di comunicazione suppongo...
Originariamente inviato da jumpermax
azz peccato... non avrà più finestre di comunicazione suppongo...
Beh credo di no, ma non erano nemmeno previste, anzi non era nemmeno previsto che le batterie durassero così a lungo.
Il suono di Titano:
15 January 2005
Audio recordings made by the Huygens Atmospheric Structure Instrument (HASI), which includes an acoustic sensor, during and after Huygen's descent, 14 January 2005. These audio tracks are from the most distant world ever visited by a man-made probe.
Descent:
http://esamultimedia.esa.int/multimedia/sounds/cassini-huygens/Sound_of_Titan-Nominal_Decent.mp3
Post-landing:
http://esamultimedia.esa.int/multimedia/sounds/cassini-huygens/Sound_of_Titan-After_Impact.mp3
The first file, made during the descent, includes a 'lot of acoustic noise', according to Peter Falkner from the HASI science team. The second, made after landing, features only silence; the sound that can be heard is merely electronic noise from an on-board amplifier.
Come è già stato scritto diverse volte, Hyugens era dotata di molti strumenti avanzatissimi, tra i quali due fotocamere ad alta risoluzione. La durata della missione stimata era di poco meno di 3 ore, con la discesa e mezz'ora dopo l'atterraggio. Questo perchè la durata della batterie, che tra l'altro dovevano alimentare tutti gli strumenti di bordo, era ovviamente ridotta, e perchè Cassini dopo poco la fine stimata delle batterie scompariva sotto la linea dell'orizzonte.
Huygens mission ends
BY WILLIAM HARWOOD
Posted: January 14, 2005
NASA's Cassini Saturn orbiter has turned back toward Earth and started transmitting stored data from Europe's Huygens probe, which was still broadcasting a faint carrier signal from the surface of the moon Titan more than two hours after touching down and well after Cassini had turned away.
The carrier signal, detected by an Earth-based radio telescope network, confirmed the spacecraft survived atmospheric entry and reached the surface of Titan around 7:45 a.m. EST (1245 GMT), within 11 minutes or so of the predicted impact time.
At Saturn's distance of 751 million miles, the carrier was 50 quadrillion times weaker than the FM radio signal picked up by a car radio, according to an engineer at the Jet Propulsion Laboratory in Pasadena, Calif. The signal continued until well after Cassini dropped below Titan's horizon two hours after touchdown, surprising scientists at the European Space Agency's Space Operations Center in Germany.
The Cassini orbiter spent the morning out of contact with Earth, aiming its high gain antenna at the Huygens landing site to collect the entry probe's priceless science data. The orbiter was programmed to turn back toward Earth a few minutes before 10 a.m. EST and officials confirmed the Cassini started transmitting stored data as expected. But the first actual science data from Huygens' suit of instruments was not expected to show up on the ground until around 11:15 a.m.
"This is clearly an engineering success," said ESA project scientist Jean-Pierre Lebreton. "But at this moment, we cannot say more. ... We have not seen any real data yet."
Titan is the sixth world in the solar system, after the moon, Venus, Mars, Jupiter and an asteroid, that has been visited by a robotic emissary from Earth. But Titan is by far the most distant such planetary outpost.
"This whole thing of approaching Titan, descending down through its atmosphere and landing on its surface to me is like out of Jules Verne," said Carolyn Porco, the Cassini imaging team leader. "It's like a combination of 'Journey to the Moon' and '20,000 Leagues Under the Sea,' all wrapped up together, it's that kind of adventure in my mind.
"We've just extended our reach twice as far as we had before when we talk about physically making contact. ... This is a big moment and because of this, we can now look in the sky and when we see Saturn, we can say we've been there and we've made our mark. In that sense, the solar system, with this one event today, has become a very much smaller place. And that is very big."
http://www.spaceflightnow.com/cassini/images/050115color.jpg
This image was returned January 14 by ESA's Huygens probe during its successful descent to land on Titan. This is the coloured view, following processing to add reflection spectra data, gives a better indication of the actual colour of the surface. Initially thought to be rocks or ice blocks, they are more pebble-sized. The two rock-like objects just below the middle of the image are about 15 centimetres (left) and 4 centimetres (centre) across respectively, at a distance of about 85 centimetres from Huygens. The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. There is also evidence of erosion at the base of these objects, indicating possible fluvial activity. Credits: ESA/NASA/University of Arizona
Originariamente inviato da Proteus
Ma non è un isotopo, il più stabile, dell'uranio ad avere numero atomici 238 mentre il plutonio, elemento transuranico non esistente, come altri con peso oltre il 240, in natura, ha il 239 ?.
Ciao
-EDIT cavolata-
http://www.spaceflightnow.com/cassini/images/050115mosaic.jpg
This composite was produced from images returned January 14 by ESA's Huygens probe during its successful descent to land on Titan. It shows a full 360-degree view around Huygens. The left-hand side, behind Huygens, shows a boundary between light and dark areas. The white streaks seen near this boundary could be ground 'fog', as they were not immediately visible from higher altitudes. As the probe descended, it drifted over a plateau (centre of image) and was heading towards its landing site in a dark area (right). From the drift of the probe, the wind speed has been estimated at around 6-7 kilometres per hour. These images were taken from an altitude of about 8 kilometres with a resolution of about 20 metres per pixel. Credits: ESA/NASA/University of Arizona
Frank1962
15-01-2005, 12:40
Originariamente inviato da GioFX
Come è già stato scritto diverse volte, Hyugens era dotata di molti strumenti avanzatissimi, tra i quali due fotocamere ad alta risoluzione.....
....queste foto non mi sembrano affatto ad alta risoluzione! :(
Originariamente inviato da Frank1962
....queste foto non mi sembrano affatto ad alta risoluzione! :(
perchè forse sono di press-release?!?
Originariamente inviato da Proteus
A me pare proprio che l'isotopo 235 sia quello fissile, l'arricchimento serve proprio ad aumentare la percentuale di questo isotopo per comporre le barre di combustibile per le centrali elettronucleari e spingendo la raffinazione si ottiene un prodotto con tanta presenza di U-235 da rendere fattibile, la coistruzione di bombe termonucleari, l'atomica esplode e fonde l'idrogeno, come quelle in stoccaggio ora.
hai ragione :p
il 238 è quello più comune in natura ;)
Originariamente inviato da Proteus
Meno male perchè già pensavo ad un deterioramento grave della mia memoria con arteriosclerosi precoce e galoppante. Mi hai quasi fatto venire uno sciopone.;) ;)
Ciao
siccome ho sempre in mente 238->239 per creare instabilità allora aveso indirettamente pensato anche 235->238 ;) invece è il contrario :) Quello sensibile ai neutroni è il 235.
Originariamente inviato da Proteus
Hai mica qualche link sulle prime foto di Cassini per caso ?. Pare che abbia fotografato cose di grande interesse oltre all'aver registrato i suoni ambientali, e mi piacerebbe dare un'occhiata.
Ciao
http://saturn.jpl.nasa.gov/multimedia/images/index.cfm
Ma perchè la esa mette sempre delle foto a risoluzioni ridicole? :muro:
Originariamente inviato da Spike
Ma perchè la esa mette sempre delle foto a risoluzioni ridicole? :muro:
come quelle giganti di ME? :O
ma gli mp3 sono fruscii totali....... ci sono anche versioni
trattate ?
Originariamente inviato da ENGINE
ma gli mp3 sono fruscii totali....... ci sono anche versioni
trattate ?
E per cosa dovrebbero trattarle? Il coretto di benvenuto non credo l'abbiano fatto :D
Frank1962
16-01-2005, 10:13
http://www.corriere.it/Primo_Piano/Scienze_e_Tecnologie/2005/01_Gennaio/16/titano.shtml
1ora luce? ......mazz se è lontano saturno!!
Originariamente inviato da gpc
E per cosa dovrebbero trattarle? Il coretto di benvenuto non credo l'abbiano fatto :D
Non hai capito..... almeno depurarli dai fruscii e i disturbi in genere che si sono inseriti sopra........
non mi dirai che quello E' il suono VERO che si sente sulla superfice o mentre la sonda scendeva..........
Io ho provato con GOLDWAVE a maneggiare i due file per vedere
se riuscivo a fare qualche cosa......... ma avete visto che stranissimo spettro sonoro che hanno ? cmq non sono riuscito a fare molto, ci vorrebbe uno studio audio e soprattutto dei tecnici audio con relative strumentazioni .
Mi sembra strano che le foto siano curate per renderle chiare e nitide e su quei due file nessuno ci ha messo mani..........
Originariamente inviato da GioFX
come quelle giganti di ME? :O
no, mi riferisco solo a questa missione. anche le foto degli anelli erano minuscole!
Curiosità...
che ci frega di andare su Titano?
non sarebbe stato meglio spendere quei soldi per le ricerche sulla fusione nucleare per produrre energia?
Il giorno in cui la fusione si potrà controllare come la fissione, avremo tanta energia per farci qualunque cosa..
ciao :)
jumpermax
16-01-2005, 20:18
Originariamente inviato da dupa
Curiosità...
che ci frega di andare su Titano?
non sarebbe stato meglio spendere quei soldi per le ricerche sulla fusione nucleare per produrre energia?
Il giorno in cui la fusione si potrà controllare come la fissione, avremo tanta energia per farci qualunque cosa..
ciao :)
già certo cosa mai ci avrà portato l'esplorazione spaziale di buono... le celle a combustibile, i satelliti per le comunicazioni... ne potevamo anche fare a meno... la scienza è anche esplorazione, non puoi ragionare a compartimenti stagni.
Originariamente inviato da ENGINE
Non hai capito..... almeno depurarli dai fruscii e i disturbi in genere che si sono inseriti sopra........
non mi dirai che quello E' il suono VERO che si sente sulla superfice o mentre la sonda scendeva..........
Io ho provato con GOLDWAVE a maneggiare i due file per vedere
se riuscivo a fare qualche cosa......... ma avete visto che stranissimo spettro sonoro che hanno ? cmq non sono riuscito a fare molto, ci vorrebbe uno studio audio e soprattutto dei tecnici audio con relative strumentazioni .
Mi sembra strano che le foto siano curate per renderle chiare e nitide e su quei due file nessuno ci ha messo mani..........
Ma certo che quello era il suono... se metti la testa fuori dal finestrino di un'aereo senti solo "fruscii"...
Per curiosità, secondo te cosa si doveva sentire?
Originariamente inviato da jumpermax
già certo cosa mai ci avrà portato l'esplorazione spaziale di buono... le celle a combustibile, i satelliti per le comunicazioni... ne potevamo anche fare a meno... la scienza è anche esplorazione, non puoi ragionare a compartimenti stagni.
Dimentichi buona parte delle tecnologie e dei materiali usati in tantissimi campi...
spinbird
16-01-2005, 21:07
Originariamente inviato da gpc
Dimentichi buona parte delle tecnologie e dei materiali usati in tantissimi campi...
come il velcro!
Io comunque sto parlando di Titano, non dell'esplorazione spaziale in genere.
L'unica cosa utile di Titano è che ha un atmosfera simile a quella terrestre primordiale..
E cosa c'è di quella atmosfera che non sarebbe riproducibile in laboratorio?
Marte sarebbe decisamente molto più interessante, a livello teorico potrebbero essere esistita su Marte una natura simile a quella terreste con vegetazione e animali evoluti, e magari ci sono in giro fossili o le ossa dei "dinosauri marziani" per il pianeta.
Invece Titano mi sembra altamente inutile... boh.
Comunque non vedo tutte ste grandi innovazioni portate dall'esplorazione spaziale.. infatti l'unica che si cita sempre è il velcro..
Sono molto utili i sistemi di satelliti che girano attorno alla Terra, per le telecomunicazioni, per la sicurezza e per altro... ma andare oltre la Terra, fino ad oggi non è servito a nulla.
Le grandi innovazioni sono generalmente portate dalle guerre e dalle tecnologie militari
incredibile, guarda che al di là delle tecnologie derivate dalle missioni spaziali la cosa più importante è e rimane l'aspetto scientifico: altrimenti perchè si chiamarebbero missioni scientifiche spaziali (o space science)?
Con chi considera inutile conoscere la storia e l'evoluzione dell'universo e del sistema solare c'è poco da discutere.
E, tanto per la cronaca, parli di Titano e tutto il resto come se si conoscesse già tutto. Anzi, peggio ancora, parli di Marte come più misterioso di Titano. Ma dico, scherziamo?
Huygens è la prima cosa costruita dall'uomo a giungere sulla superficie di un pianeta del sistema solare esterno. Titano oltretutto è il satellite che più ha affascinato gli scienziati da sempre, per la presenza unica di un'atmosfera la più simile a quella terrestre, che si considera essere assai vicina a quella della Terra all'inizio della sua vita geologica.
Oltretutto, quello che si IPOTIZZAVA sulla luna di saturno sta venendo largamente modificato dai dati raccolti dalla sonda, nella missione scientifica più complessa della storia.
Una missione umana su Titano è fattibile allo stato attuale delle tecnologie? Costi a parte...
spinbird
16-01-2005, 22:59
Originariamente inviato da drakend
Una missione umana su Titano è fattibile allo stato attuale delle tecnologie? Costi a parte...
ma in quale fanta epoca vivete?
Matrixbob
16-01-2005, 23:01
Originariamente inviato da drakend
Una missione umana su Titano è fattibile allo stato attuale delle tecnologie? Costi a parte...
Sarà fattibile solo dopo una base sulla luna e una su marte quindi, con un po' di fortuna, la potranno iniziare quando noi saremmo dei vecchietti decrepiti :)
jumpermax
16-01-2005, 23:12
Originariamente inviato da spinbird
ma in quale fanta epoca vivete?
beh ha aggiunto una parolina che è magica direi "costi a parte".
Credo che la biologia per ora costituisca un ostacolo insormontabile... a meno che non riescano a sviluppare un veicolo in grado di andare e tornare da titano in un paio di anni (parliamo di 1400 milioni di km Marte che già è al limite rimane ad un 100naio circa) gli effetti di una permanenza così lunga nello spazio sarebbero deleteri.
Se saremo fortunati vedremo il primo uomo su Marte... ed è già un obbiettivo tecnologicamente molto difficile...
jumpermax
16-01-2005, 23:13
Originariamente inviato da GioFX
incredibile, guarda che al di là delle tecnologie derivate dalle missioni spaziali la cosa più importante è e rimane l'aspetto scientifico: altrimenti perchè si chiamarebbero missioni scientifiche spaziali (o space science)?
Con chi considera inutile conoscere la storia e l'evoluzione dell'universo e del sistema solare c'è poco da discutere.
E, tanto per la cronaca, parli di Titano e tutto il resto come se si conoscesse già tutto. Anzi, peggio ancora, parli di Marte come più misterioso di Titano. Ma dico, scherziamo?
Huygens è la prima cosa costruita dall'uomo a giungere sulla superficie di un pianeta del sistema solare esterno. Titano oltretutto è il satellite che più ha affascinato gli scienziati da sempre, per la presenza unica di un'atmosfera la più simile a quella terrestre, che si considera essere assai vicina a quella della Terra all'inizio della sua vita geologica.
Oltretutto, quello che si IPOTIZZAVA sulla luna di saturno sta venendo largamente modificato dai dati raccolti dalla sonda, nella missione scientifica più complessa della storia.
E' il ragionare nella scienza con mentalità aziendale. O lo studio ha applicabilità immediata oppure è inutile...
Originariamente inviato da spinbird
ma in quale fanta epoca vivete?
Ora non si può fare nemmeno una domanda per soddisfare una propria curiosità che deve arrivare il sapientone a fare il belloccio?
Lascia stare le fanta epoche, Titano e tutte queste cose difficili per te: ti serve in primo luogo un corso di umiltà accelerato.
jumpermax
16-01-2005, 23:51
Originariamente inviato da drakend
Ora non si può fare nemmeno una domanda per soddisfare una propria curiosità che deve arrivare il sapientone a fare il belloccio?
Lascia stare le fanta epoche, Titano e tutte queste cose difficili per te: ti serve in primo luogo un corso di umiltà accelerato.
bboni... :O se avete questioni personali ci sono i pvt ;)
ChristinaAemiliana
17-01-2005, 00:06
Originariamente inviato da jumpermax
bboni... :O se avete questioni personali ci sono i pvt ;)
Ehi, non si consiglia alla gente di scornarsi in pvt! :sofico:
SPAZIO: TITAN SU SATURNO, L'ESA FESTEGGIA
(AGI/AFP) - Darmstadt (Germania), 14 gen. - L'Agenzia spaziale europea (Esa) brinda al successo della missione che oggi ha portato la sonda Titan sul suolo di Saturno. Le prime foto della superficie del pianeta sono attese per le prossime ore.
Il direttore generale dell'Esa, Jean Jacques Dordain ha riferito che a terra e' arrivato un flusso di dati sulla missione attraverso la sonda Cassini, che orbita attorno a Titano. "Speriamo di avere i primi risultati stasera", ha detto ai giornalisti, definendo la missione "un fantastico successo dell'Europa". (AGI) .
141814 GEN 05
http://www.agi.it/news.pl?doc=200501141814-1210-RT1-CRO-0-NF20&page=0&id=agionline.europa
jumpermax
17-01-2005, 01:15
Originariamente inviato da ChristinaAemiliana
Ehi, non si consiglia alla gente di scornarsi in pvt! :sofico:
Infatti era sottointeso che dovranno educatamente cercare di risolvere la loro divergenza confrontando in modo rispettoso i loro differenti punti di vista... :D
oscuroviandante
17-01-2005, 11:05
Mi intrufolo nella discussione....:D
Da appassionato di Sci-Fi non posso fare altro che sognare quando leggo queste notizie.
Fosse per me la ricerca spaziale dovrebbe avere stanziamenti 100 volte più altri di adesso.
Molti si chiedono il perchè andare a buttare via soldi ...
Un motivo oggi davvero da fantascienza può essere lo sfruttamento di idrocarburi.
Titano ne è totalmente ricoperto a quanto sembra.
Già oggi si parla di lottizzazione della Luna.
Mettiamo caso che entro la fine del secolo incominci una "corsa all'oro" dei giacimenti di idrocarburi e minerali.
Magari nel 2099 l'Europa potrebbe affermare che nel 2005 una propria sonda fu la prima ad atterrarci e rivendicare la proprietà dell'intero pianeta.
So di parlare di fantascienza ...ma fino a quanto?
Guardate Star Trek
Il teletrasporto...... fatto
L'antimateria..........praticamente fatta
Velocità Warp.........progetto teorico di un motore stellare (Un centro di ricerca Inglese se non mi sbaglio)
dai chi non ha mai sognato di dire SUL SERIO "signor sulu...velocità Warp...attivare" :D
Matrixbob
17-01-2005, 11:11
Originariamente inviato da oscuroviandante
Guardate Star Trek
Il teletrasporto...... fatto
L'antimateria..........praticamente fatta
Velocità Warp.........progetto teorico di un motore stellare (Un centro di ricerca Inglese se non mi sbaglio)
Tu stai sognando ad occhi aperti, è tutto altamente instabile ed approssimativo quanto hai elencato.
Saresti dovuto vivere tra 100 anni, allora si che magari qualche sfizio te lo toglievi :)
jumpermax
17-01-2005, 11:13
Originariamente inviato da oscuroviandante
Mi intrufolo nella discussione....:D
Da appassionato di Sci-Fi non posso fare altro che sognare quando leggo queste notizie.
Fosse per me la ricerca spaziale dovrebbe avere stanziamenti 100 volte più altri di adesso.
Molti si chiedono il perchè andare a buttare via soldi ...
Un motivo oggi davvero da fantascienza può essere lo sfruttamento di idrocarburi.
Titano ne è totalmente ricoperto a quanto sembra.
Già oggi si parla di lottizzazione della Luna.
Mettiamo caso che entro la fine del secolo incominci una "corsa all'oro" dei giacimenti di idrocarburi e minerali.
Magari nel 2099 l'Europa potrebbe affermare che nel 2005 una propria sonda fu la prima ad atterrarci e rivendicare la proprietà dell'intero pianeta.
So di parlare di fantascienza ...ma fino a quanto?
Guardate Star Trek
Il teletrasporto...... fatto
L'antimateria..........praticamente fatta
Velocità Warp.........progetto teorico di un motore stellare (Un centro di ricerca Inglese se non mi sbaglio)
dai chi non ha mai sognato di dire SUL SERIO "signor sulu...velocità Warp...attivare" :D
Anche se è vero che questi pianeti sono ricchi di idrocarburi dubito che ce ne faremo qualcosa... salvo trovarsi ingenti quantità di ossigeno. Su titano infatti si dovrebbe girare con serbatoi di ossigeno anzichè di carburante... ma comunque sempre l'ossigeno sarebbe necessario.
Originariamente inviato da oscuroviandante
Guardate Star Trek
Il teletrasporto...... fatto
L'antimateria..........praticamente fatta
Velocità Warp.........progetto teorico di un motore stellare (Un centro di ricerca Inglese se non mi sbaglio)
http://deepnet.altervista.org/altro/marmotta.gif
a parte la marmotta, mi sembra un po assurdo poter dare per superati traguardi come il teletrasporto, l' antimateria, e il motore Warp.
In star trek si teletrasportano persone, qui a malapena fotoni, privi di massa effettiva (nonostante Erwin Schrodinger e Werner Heisenberg non sarebbero d'accordo).
L'antimateria e' stata ottenuta per una frazione di secondo, e in maniera del tutto astabile (non instabile).
Peraltro si sono ottenuti al piu' antiatomi di antiidrogeno al cern, e non si sono comportati come avrebbero dovuto.
Sul motore warp lessi qualcosa a riguardo, ma si sentiva parlare di deformazioni spazio temporali sull' onda gaudge.
Onestamente temo che ce ne voglia ancora per poter andare a fare un picnic su saturno.;)
jumpermax
17-01-2005, 11:38
Originariamente inviato da Fede
http://deepnet.altervista.org/altro/marmotta.gif
a parte la marmotta, mi sembra un po assurdo poter dare per superati traguardi come il teletrasporto, l' antimateria, e il motore Warp.
In star trek si teletrasportano persone, qui a malapena fotoni, privi di massa effettiva (nonostante Erwin Schrodinger e Werner Heisenberg non sarebbero d'accordo).
L'antimateria e' stata ottenuta per una frazione di secondo, e in maniera del tutto astabile (non instabile).
Peraltro si sono ottenuti al piu' antiatomi di antiidrogeno al cern, e non si sono comportati come avrebbero dovuto.
Sul motore warp lessi qualcosa a riguardo, ma si sentiva parlare di deformazioni spazio temporali sull' onda gaudge.
Onestamente temo che ce ne voglia ancora per poter andare a fare un picnic su saturno.;)
beh senza scomodare star trek già se si riuscisse a perfezionare i motori ionici e scendessero di un ordine di grandezza i costi di messa in orbita di materiale se non saturno forse marte sarebbe a portata turistica... di sicuro a portata c'è già il turismo orbitale, almeno per chi ha qualche decina di milioni di dollari da spendere...
oscuroviandante
17-01-2005, 11:40
e io che volevo invitarvi ad un lan party intergalattico su Urano...
CALMA CALMA....
so che warp ,teletrasporto e compagnia bella non sono traguardi raggiunti e chissa se e quando li raggiungeremo.
Ma il fatto che illustri scienziati li stiano studiando per applicazioni pratiche fa pensare che a volte la fantascienza non è tanto lontana dalla realtà.
Nel medioevo se qualcuno affermava che una sonda automatica avrebbe raggiunto un satellite di un altro pianeta ....l'avrebbero allegramente messo al rogo.
Riuscireste davvero ad immaginare il mondo fra 500 anni?
Originariamente inviato da jumpermax
beh senza scomodare star trek già se si riuscisse a perfezionare i motori ionici e scendessero di un ordine di grandezza i costi di messa in orbita di materiale se non saturno forse marte sarebbe a portata turistica... di sicuro a portata c'è già il turismo orbitale, almeno per chi ha qualche decina di milioni di dollari da spendere...
non lo metto in dubbio...:)
P.s: certo che meraviglia, spero prima di non esserci piu' di poter provare l'ebrezza della O gravity.
oscuroviandante
17-01-2005, 11:41
Originariamente inviato da jumpermax
beh senza scomodare star trek già se si riuscisse a perfezionare i motori ionici e scendessero di un ordine di grandezza i costi di messa in orbita di materiale se non saturno forse marte sarebbe a portata turistica... di sicuro a portata c'è già il turismo orbitale, almeno per chi ha qualche decina di milioni di dollari da spendere...
e pensare che i motori ionici erano fantascienza degli anni 50....
Originariamente inviato da oscuroviandante
Riuscireste davvero ad immaginare il mondo fra 500 anni?
non mi tange, e mi fa solo invidia:)
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