View Full Version : [Space] NASA - Deep Impact - Send your name to a comet!
NASA - Deep Impact Mission
Jet Propulsion Laboratory with University of Maryland and Ball Aerospace & Technology Corp.
Deep Impact è la prossima missione scientifica della NASA. Il suo scopo è quello di raggiungere la cometa Tempel 1 che passerà vicino alla Terra il prossimo luglio del 2004 e far schiantare una una sonda, detta Impactor, in modo da creare un cratere di più di 25 m di profondità e 100 di diametro, così da poter studiare l'intero ghiacciato di una cometa.
L'analisi si protrarrà per 9 mesi e verrà eseguita dalla sonda in orbita attorno alla cometa (detta "flyby spacecraft") e dall'impactor all'interno del cratere. Il cratere sarà scavato utilizzando la sola energia cinetica della sonda d'impatto, ben 19 Gjoules (pari a 4,8 tonnellate di TNT), generata dalla massa della sonda (370 kg) e dalla velocità di impatto (pressapoco 10,2 m/s).
Brevemente:
- Lancio: 30 dicembre 2004 dal KSC con un razzo Delta II
- Incontro (randeveuz) con la cometa Tempel 1: 4 luglio 2004
- Separazione dell'Impactor: 24 prima del randeveuz
- Velocità d'impatto: 10,2 m/s
- Distanza minima sonda orbitante: 500 km
- Fine missione: Agosto 2005
Fatti della missione (tutte le informazioni disponibili):
Mission - Fact Sheet (http://deepimpact.jpl.nasa.gov/mission/factsheet-text.html)
http://deepimpact.jpl.nasa.gov/gallery/jpg/traj_new_color_med.jpg
Per questa missione la NASA ha preparato una speciale campagna per coninvolgere direttamente la gente: Send your name to the comet!
E' aperta a chiunque, da tutto il mondo, e permette di inserire il proprio nome nel database, che poi verrà inciso su un disco che sarà inserito all'interno della sonda d'impatto che si schianterà sulla cometa, rimanendo lì per l'etenità.
Send your name to a comet! (http://deepimpact.jpl.nasa.gov/sendyourname/index.html)
What is the Send Your Name to a Comet campaign?
Glad you asked! The Deep Impact mission will dig deep beneath the surface of a comet to get a first-ever look at the frozen collection of ice and dust left over from the formation of the solar system. Why are we doing it? We learn about comets by studying the ice and dust that flows naturally from a comet as it is warmed by the Sun. But we will learn additional information by getting down inside where the more pristine material is hidden. Scientists expect to find hidden clues about how the solar system formed when they look at the structure of Comet Tempel 1. To accomplish our goal, we will have to make a deep crater in the surface with a 370 kg (820 lb) copper-nosed impactor spacecraft. Telescopes and instruments on the sister spacecraft, the flyby, will observe the impact from a safe distance of 500 km (300 mi).
Sound exciting? Want to be part of it? Well, you can!
You can send your name crashing into Comet Tempel 1 by going to Send Your Name to a Comet. Once you have filled in and submitted the form, your name will be recorded along with many others on a disc mounted on the impactor spacecraft. You may choose to print out a personalized commemorative certificate. Bookmark your certificate for later viewing and tell your friends, so they can send their name to a comet as well!
Dopo aver inserito il nome vi verrà rilasciato un certificato elettronico personale.
Ad oggi si sono iscritte quasi 500.000 persone. Fate presto: termina il 31 gennaio 2004.
jumpermax
25-01-2004, 23:31
non è per togliere poesia a tutto ciò ma... insomma è come arrivare in cima all'everest e buttare delle cartacce per terra dopo averle firmate, o incidere il proprio nome su un albero secolare... che gusto c'è? Ci sono modi migliori per lasciare tracce del nostro passaggio...
bella l'idea dei nomi... cmq questo disco verrà sicuramente polverizzato all'impatto vista la potenza stimata...
PaTLaBoR
26-01-2004, 08:24
già fatto!
ti rilasciano pure un attestato che puoi stampare...
l'ho fatto 4 mesi fa
OLD :D
PaTLaBoR
26-01-2004, 18:38
Originariamente inviato da GioFX
bravo patlabor!
però ne voglio fare un altro con il mio nick :D
Originariamente inviato da PaTLaBoR
però ne voglio fare un altro con il mio nick :D
Facci mettere anche l'avatar che e' carino :sofico:
il mio nome è nella storia :cool:
Adesso gli intasiamo il sito... :D
Originariamente inviato da Korn
il mio nome è nella storia :cool:
Secondo me il tuo non ci sta sul CD e lo scartano... :O
E se poi gli alieni trovano il mio nome e mi vengono a cercare?:fiufiu:
PaTLaBoR
26-01-2004, 18:54
Originariamente inviato da gpc
Facci mettere anche l'avatar che e' carino :sofico:
allora ne devo fà tre.... ok! :D
Originariamente inviato da gpc
Secondo me il tuo non ci sta sul CD e lo scartano... :O
:eek: :cry:
magari porta sfiga... tiè!
jumpermax
27-01-2004, 00:06
volete vedere l'orbita della cometa in tempo reale?
ragazzi da non perdere questo link.... è davvero interessante!
http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=tempel+1&search=Search
Frank1962
27-01-2004, 00:14
sarebbe stato + carino se lo avessero fatto per una sonda da mandare verso marte :(
Deep Impact: NASA's crash course in comet science
BY JUSTIN RAY
SPACEFLIGHT NOW
NASA launches a space mission in January to blast a hole in the side of a comet and learn more about the make up of these icy bodies.
http://www.spaceflightnow.com/delta/d311/images/deepimpact.jpg
The Deep Impact mothership releases its copper laden impactor at Comet Tempel 1. Credit: NASA/JPL
As ancient wanderers of the solar system laden with primordial material frozen in time, comets offer humanity clues to some of the most fundamental questions about conditions when the planets were forming more than four billion years ago.
Buried inside the hearts of these rocky snowballs are the pristine building blocks that hold the chemical records from the solar system's creation. Comets likely peppered the young Earth, possibly delivering the organic materials needed for the rise of life, the water for our oceans and even playing a role in generating the atmosphere.
To capture an unprecedented glimpse at this preserved material, NASA's Deep Impact spacecraft is scheduled for launch January 12 carrying a copper bullet that will be fired into the heart of Tempel 1 next July 4, carving out a stadium-sized crater.
"We're doing this to discover the comet's structure and makeup," said Rick Grammier, NASA's Deep Impact project manager. "This is like swinging an 820-pound slug of copper at this thing and seeing what happens."
Sophisticated instruments on the Deep Impact's mothership will record the blast and peer into a comet's interior for the first time. Observatories around the globe, plus the Hubble and Spitzer space telescopes, will be watching the aftermath to collect crucial information about the dusts and gases blown out of Tempel 1.
Conquering the mysteries
"My interest in comets all along has been trying to understand the chemical composition and to use that to put constraints on our theories of what conditions were like 4.5 billion years ago when the whole solar system was forming," said Michael A'Hearn, astronomer from the University of Maryland and the Deep Impact principal investigator.
"What we see coming out of comets as gas and dust is stuff that has been modified because it is very near the surface, and every time the comet goes around the sun the surface gets heated. So there have been changes in the surface layers... What I really want to do is figure out how different the surface is from what's inside.
Discovered on April 3, 1867 by Ernst Wilhelm Leberecht Tempel in Marseilles, France, Comet 9P/Tempel 1 currently circles the sun every 5.5 years. Its orbit lies between Mars and Jupiter, providing the Deep Impact mission a perfect target for reaching with a modest launch vehicle, striking at high speed and being visible from Earth at impact about 130 million kilometres away.
http://www.spaceflightnow.com/delta/d311/images/trajectory.jpg
Deep Impact launches in January and slams its impactor into Comet Tempel 1 in July. Graphic: Mark McLellan/Astronomy Now
The exact size and shape of the comet's nucleus is unclear from observations made to date. It is thought to be elongated and six kilometres in diameter. How Tempel 1 will react to the impact is also a mystery, but scientists do not believe the comet will shatter apart.
"It has turned out that the physics of how the impact occurs is also a large unknown because we know so little about fragility or strength of the cometary nuclei generally. We certainly know nothing about this particular comet," A'Hearn said.
"There is an outside chance that we could break the comet. We don't think that will happen... We don't think that the comet can propagate a shockwave through from one side to the other so that you can break it because we don't think it's that strong and cohesive everywhere."
Starting two months before the encounter, Deep Impact commences its science observations in earnest, painting a picture of what the spacecraft should expect at arrival and giving ample time to change the approach strategy if necessary. Specifically, mission planners want to pin down how the comet nucleus rotates and examine the jets of gas and dust streaming away from Tempel 1.
Demolition day
One day before the big bang, the mothership releases the impactor. This one-metre diameter, 0.8-metre tall projectile is equipped with an autonomous navigation computer, cameras and a propulsion system to guide itself toward a suitable impact point that is well lit. The mothership performs an evasive manoeuvre, plotting a trajectory to fly past the comet shortly after the impact.
"Early images from the impactor are mainly for navigation... to make sure that it hits in an illuminated area and not in a dark area. As we get closer, those images become important for science because as we get closer and closer we will get higher and higher spatial resolution. We will directly see the change in texture as you change spatial scale. Assuming the camera on the impactor survives until very shortly before impact, these will be the highest resolution pictures ever of a cometary nucleus, much higher than we will get from the flyby [spacecraft]," A'Hearn said.
The flyby craft will be using its spectrometer to identify and quantify the materials across the comet's dust- and gas-filled coma head and taking images in a wide variety of different colours. Since the nucleus is believed to have a 41-hour rotational period, less than half will be seen at good resolution.
"Shortly before the time of impact, the flyby spacecraft determines how fast it is having to rotate to keep the high-resolution camera pointed at the nucleus. It uses that to calculate when it will be at closest approach and then knowing the difference velocity, when the impactor will impact. It sends that information up to the impactor so the impactor can optimise the imaging sequence at the expected time of impact. Flyby uses it internally, also, to optimise the imaging sequence for the time of closest approach," A'Hearn said.
Information from both craft is fed back to Earth in real-time in case comet shrapnel fatally wounds the mothership during the encounter.
Hit and run
The 370-kilogramme impactor and comet collide at 10.2 km/s, releasing the energy equivalent of 4.4 tonnes of exploding TNT and creating the ultimate fireworks display for Americans on the Fourth of July.
"We put the impactor in the comet's path so that the comet overtakes it. So it is like standing in the middle of the road with semi truck bearing down on you," Grammier said.
The intense forces vaporize the projectile as the circular crater is rapidly excavated. "We expect it could put a crater about the size of a house up to the size of a football stadium and it could be anywhere from seven to 14 stories deep.
"As a result of forming the crater, it will throw out a bunch of the surface and interior material that is displaced. It will come up in a big cloud that will reflect the sunlight. So you will see a large brightening, and you will see that brightening from telescopes on Earth as well. Then you will see it slowly dissipate as the material either settles back down onto the comet itself or becomes part of its coma dust cloud. What we are hoping to see to from the flyby spacecraft viewpoint is being able to look all the way down into the interior of the crater and determine what its materials are made of," Grammier continued.
"Since these are the original remnants of the solar system formation, not knowing how the exterior of a comet relates to interior, what we are hoping to do is expose all of that fresh material and see the material that was actually present at the formation of the solar system."
The impact occurs with the mothership 8,600 kilometres away and closing fast. The medium-resolution camera will be taking pictures as swiftly as possible to capture the moment of impact. "We are hoping to catch a bright flash that will last less than a second by taking four or eight frames per second," A'Hearn said. The high-resolution camera snaps pictures at a slower pace.
http://www.spaceflightnow.com/delta/d311/images/041214deepimpact.jpg
An artist's concept shows the Deep Impact mothership watching the impactor smash into Comet Tempel 1. Credit: Ball Aerospace & Technologies Corp.
Scientists expect the materials thrown out of the freshly bored hole will settle within a few minutes, permitting good visibility into the crater. The mothership has less than 14 minutes to make its observations while zooming toward the comet before passing by Tempel 1 at a distance of 500 kilometres. The craft enters a "shield mode" to protect itself from the powerful sandblasting during flight through the coma at closest approach.
"Our baseline is it will take 200 seconds to form the crater, but uncertainties in the density of the nucleus - something that we just don't know - the crater could take as long as 600 seconds to form. This was one of our mission design problems, making sure we had long enough interval to observe so that we make sure the crater finished forming before we flew by but keeping the interval small enough that we weren't so far away at the time of impact that we had no resolution. This what led us to the 800-second window between impact and the going into our shield mode through the innermost coma," A'Hearn said.
Surviving the getaway
Deep Impact has just one shot at grabbing scientific data on the primordial material packed inside the comet.
"We do maps across the nucleus after the impact to try and get spectra of the crater floor, see how different it is from the neighbouring terrain that is undisturbed," A'Hearn said. "We take some spectra off the limb to look at the gases that are coming out of the crater. As we get very close, we actually have to let the camera drift a little and take a couple of images to make sure we get crater in the high-resolution camera."
About 50 seconds before closest approach, the flyby craft orients itself with protective shielding guarding against a destructive hit by comet dust.
http://www.spaceflightnow.com/delta/d311/images/twocraft.jpg
The mothership spacecraft is seen here over the tiny impactor during final testing. Credit: NASA-KSC
"We've designed extra shielding on certain parts of the spacecraft. So when I say it turns to shield mode, what that means is it actually places those shields in the direction of the cometary dust and debris. That is meant to protect the spacecraft itself from any particle hits. That shielding was designed based on what we know today of probable particle sizes, distribution and density at that distance from the comet," Grammier said.
Despite the added protection, the mothership will be relaying its pictures and information to Earth live in case the craft doesn't survive the encounter to tell the tale afterward.
"There are worries, that is why we are transmitting as much as we can in real-time, as much as the communications system will allow us to," A'Hearn said. "The engineers have predicted that the probability of a fatal hit is down at the one or a couple percent level, given the amount of shielding we have."
Once through the dangerous region, the departing mothership manoeuvres to observe the comet's back side a quarter-hour after closest approach.
"We fly through the innermost coma, fly through the orbital plane and then turn around and look back... to take images of the other side. When we take pictures of the other side, the crater itself will be hidden, but we will still be looking to see if we can see ejecta from the crater. A likely scenario is that after we make the crater, there will be a lot spontaneous outgasing from the floor of the crater because there is very volatile ice near the surface that used to be buried deeply.
There is a reasonable chance that we would see a new jet in the coma coming from the crater - and we would see it where it comes out from behind the limb of the nucleus," A'Hearn said.
Aftermath
"We also use these look-back images to figure out the three-dimensional shape of the nucleus since we don't get to see a full rotation. We do the look-back monitoring for up to a day after impact."
Ground-based telescopes in Hawaii will have prime viewing with the comet high in the sky at the time of impact, while the southwestern U.S. and Baja California will have Tempel 1 low in the sky. But a global campaign is underway to provide thorough monitoring of the comet before and after the collision with special imaging techniques.
http://www.spaceflightnow.com/delta/d311/images/041214deepimpactart.jpg
An artist's concept shows the Deep Impact mothership watching the comet collision. Credit: Ball Aerospace & Technologies Corp.
"We may create this new jet that may persist for hours or days or weeks or even months. So we are looking for observations afterwards," A'Hearn said.
"We are trying to get complete longitude coverage so we can monitor the comet continuously from something like four days before the impact - two rotation periods - until a week after the impact."
The $320 million mission follows NASA's Stardust project that flew past Comet Wild 2 in January, catching dust particles for return to Earth in 2006. The European Rosetta mission is currently flying to Comet Churyumov-Gerasimenko where a tiny lander will be dispatched to the frigid nucleus.
If the Deep Impact mothership remains in good health, NASA could route the craft to other comets for close-up imaging by the onboard cameras, A'Hearn said.
Daemonarch
07-01-2005, 20:14
Come si fà a mettere il mio nome?
se inseriscono il database in un hd maxtor , non fa manco tempo a partire che e' gia' bello schiattato!
:O
Ciaozzz
Originariamente inviato da Daemonarch
Come si fà a mettere il mio nome?
forse sei giusto un pò in ritardo... :O
:p
Probe launched to smack heart of wandering comet
BY JUSTIN RAY
SPACEFLIGHT NOW
Posted: January 12, 2005
CAPE CANAVERAL, Fla. - Look out Comet Tempel 1, here comes Deep Impact!
A washing machine-sized projectile tucked inside its mothership spacecraft launched from Earth today on a 268-million-mile collision course that promises to create spectacular July Fourth fireworks when the 820-pound copper-tipped bullet smashes into the comet's frigid heart.
http://spaceflightnow.com/delta/d311/images/050112launch.jpg
The Deep Impact blasts off atop a Boeing Delta 2 rocket from Cape Canaveral, Florida. Credit: Boeing photo by Carleton Bailie
Comets are wandering cosmic time capsules preserving 4.5-billion-year-old primordial material that holds the chemical records of the solar system's creation. Deep Impact's violent rendezvous with Tempel 1 is designed to burst through the crust coating the comet's nucleus, form a stadium-sized crater and offer an unprecedented glimpse at ancient ices packed beneath the surface.
"What we see coming out of comets as gas and dust is stuff that has been modified because it is very near the surface, and every time the comet goes around the sun the surface gets heated. So there have been changes in the surface layers... What I really want to do is figure out how different the surface is from what's inside," said Michael A'Hearn, astronomer from the University of Maryland and the Deep Impact principal investigator.
The pristine building blocks buried inside these rocky snowballs will tell astronomers what conditions were like when the solar system was spawning planets. Uncovering the compositional fingerprints of comets has become a priority for scientists because these objects peppered the young Earth, possibly delivering the organic materials needed for the rise of life, the water for our oceans and even playing a role in generating the atmosphere.
"Deep Impact is a bold, innovative and exciting mission which will attempt something never done before to try to uncover clues about our own origins," said Andy Dantzler, acting director of the Solar System Division at NASA Headquarters.
"Why understand comets? Why study comets at all? Comets are the most primitive bodies in our solar system and they are made up of the very material from which all of the planets and the sun, in fact, are made."
http://spaceflightnow.com/delta/d311/images/050112impact.jpg
An artist's concept shows the Deep Impact projectile hitting the comet while the mothership flies past. Credit: NASA
Past spacecraft have flown close to comets, but Deep Impact will be the first to reach and out touch one.
"We're really excited about this mission," said Rick Grammier, Deep Impact project manager at the Jet Propulsion Laboratory in Pasadena, Calif. "We're doing something that's never been done before, we're actually going to go smash a big piece of copper into a comet nucleus and see what happens and see what's inside."
About 24 hours before arriving at the comet, the explosive bolts holding the projectile within the Deep Impact mothership will detonate and the impactor spring-ejects for its cruise to collision. Both craft were built by Ball Aerospace.
The impactor, a stubby-nosed bullet about two-and-a-half feet tall and three feet in diameter, sports a manhole cover-sized disc of copper with even more copper mass behind it to penetrate as deep into the comet as possible. A quarter of the impactor's launch weight is copper.
"We don't know what comets are made of, we don't know how strong they are. They could be weak and fluffy like a bowl of corn flakes, it could be like a concrete sidewalk that we are hitting. Part of the challenge in the design of the impactor was to take into account either possibility," Jay Melosh, Deep Impact co-investigator.
http://spaceflightnow.com/delta/d311/images/050112steam.jpg
The Delta rocket soars away from Earth. Credit: Boeing photo by Carleton Bailie
Deep Impact began its voyage atop a Boeing Delta 2 rocket, blasting off at 1:47:08 p.m. EST (1847:08 GMT) from pad 17B at Cape Canaveral Air Force Station, Florida.
The three-stage booster took an eastward heading, achieving an initial parking orbit around Earth less than 10 minutes after launch. Another engine firing nudged the rocket higher, and then the solid-fueled third stage motor propelled the spacecraft out of Earth orbit to cap the 34-minute launch sequence.
"We had a perfect launch," NASA launch manager Omar Baez said.
But an overly conservative setting for a temperature gauge put the Deep Impact spacecraft into a protective safe-mode soon after separating from the Delta rocket. The parameter can be adjusted and engineers were optimistic Deep Impact would return to normal operating conditions within the next 24 hours.
Today Comet Tempel 1 is about 160 million miles away in the asteroid belt on the inbound route of its orbit around the sun. It remains in a quiet state but that won't last much longer.
"The comet will be active when we encounter it. It'll be as close to the sun as it ever gets, it will be boiling gas and dust off and we have to go through that before we can strike the comet," Melosh said.
Starting two months before the encounter, Deep Impact commences its science observations in earnest, painting a picture of what the spacecraft should expect at arrival and giving ample time to change the approach strategy if necessary. Specifically, mission planners want to pin down how the comet nucleus rotates and examine the jets of gas and dust streaming away from Tempel 1.
Discovered on April 3, 1867 by Ernst Wilhelm Leberecht Tempel in Marseilles, France, Comet 9P/Tempel 1 currently circles the sun every 5.5 years. Its orbit lies between Mars and Jupiter, providing the Deep Impact mission a perfect target for reaching with a modest launch vehicle, striking at high speed and being visible from Earth at impact.
http://spaceflightnow.com/delta/d311/images/deepimpact.jpg
The Deep Impact mothership releases its copper laden impactor at Comet Tempel 1. Credit: NASA/JPL
The exact size and shape of the comet's nucleus is unclear from observations made to date. It is thought to be elongated and 3.7 miles in diameter. How Tempel 1 will react to the impact is also a mystery, but scientists do not believe the comet will shatter apart.
"It has turned out that the physics of how the impact occurs is also a large unknown because we know so little about fragility or strength of the cometary nuclei generally. We certainly know nothing about this particular comet," A'Hearn said.
"There is an outside chance that we could break the comet. We don't think that will happen... We don't think that the comet can propagate a shockwave through from one side to the other so that you can break it because we don't think it's that strong and cohesive everywhere."
The impactor is equipped with an autonomous navigation computer, cameras and a propulsion system to guide itself toward a suitable impact point that is well lit. After releasing the impactor, the mothership performs an evasive maneuver, plotting a trajectory to fly past the comet shortly after the impact.
"Early images from the impactor are mainly for navigation... to make sure that it hits in an illuminated area and not in a dark area. As we get closer, those images become important for science because as we get closer and closer we will get higher and higher spatial resolution. We will directly see the change in texture as you change spatial scale. Assuming the camera on the impactor survives until very shortly before impact, these will be the highest resolution pictures ever of a cometary nucleus, much higher than we will get from the flyby [spacecraft]," A'Hearn said.
http://spaceflightnow.com/delta/d311/images/050112fairing.jpg
The Deep Impact spacecraft is seen packaged atop the Delta rocket as the nose cone is installed during in the final days before liftoff. Credit: NASA-KSC
Sophisticated instruments on the mothership will record the blast and peer into a crater that is formed. Meanwhile, observatories around the globe, plus the Hubble, Chandra and Spitzer space telescopes, will be watching the aftermath to collect crucial information about the dusts and gases blown out of Tempel 1.
Sky watchers in the western U.S., Hawaii, New Zealand, eastern Australia and the South Pacific could be able to see the impact, which happens 83 million miles away from Earth around 2 a.m. EST (0600 GMT) July 4.
"We expect to provide some great fireworks for all our observatories," said Karen Meech, Deep Impact co-Investigator at the Institute for Astronomy in Hilo, Hawaii "That's exciting, to do it on July Fourth."
The flyby craft will be using its spectrometer to identify and quantify the materials across the comet's dust- and gas-filled coma head and taking images in a wide variety of different colors. Since the nucleus is believed to have a 41-hour rotational period, less than half will be seen at good resolution.
"Shortly before the time of impact, the flyby spacecraft determines how fast it is having to rotate to keep the high-resolution camera pointed at the nucleus. It uses that to calculate when it will be at closest approach and then knowing the difference velocity, when the impactor will impact. It sends that information up to the impactor so the impactor can optimize the imaging sequence at the expected time of impact. Flyby uses it internally, also, to optimize the imaging sequence for the time of closest approach," A'Hearn said.
Information from both craft is fed back to Earth in real-time in case comet shrapnel fatally wounds the mothership during the encounter.
The impactor and comet collide at 23,000 mph, releasing the energy equivalent of 4.5 tons of exploding TNT.
"We put the impactor in the comet's path so that the comet overtakes it. So it is like standing in the middle of the road with semi truck bearing down on you," Grammier said.
The intense forces vaporize the projectile as the circular crater -- perhaps 300 feet in diameter and 100 feet deep -- is rapidly excavated.
"We expect it could put a crater about the size of a house up to the size of a football stadium and it could be anywhere from seven to 14 stories deep.
"As a result of forming the crater, it will throw out a bunch of the surface and interior material that is displaced. It will come up in a big cloud that will reflect the sunlight. So you will see a large brightening, and you will see that brightening from telescopes on Earth as well. Then you will see it slowly dissipate as the material either settles back down onto the comet itself or becomes part of its coma dust cloud. What we are hoping to see to from the flyby spacecraft viewpoint is being able to look all the way down into the interior of the crater and determine what its materials are made of," Grammier continued.
"Since these are the original remnants of the solar system formation, not knowing how the exterior of a comet relates to interior, what we are hoping to do is expose all of that fresh material and see the material that was actually present at the formation of the solar system."
"By understanding and watching how this crater develops, and then fine-tuning our computer models to reproduce what is actually observed, we can determine how the comet is put together," added Don Yeomans, Deep Impact project scientist from the Jet Propulsion Lab.
The impact occurs with the mothership 5,400 miles away and closing fast. The medium-resolution camera will be taking pictures as swiftly as possible to capture the moment of impact. "We are hoping to catch a bright flash that will last less than a second by taking four or eight frames per second," A'Hearn said. The high-resolution camera snaps pictures at a slower pace.
http://spaceflightnow.com/delta/d311/images/050112cameras.jpg
The mothership's high-resolution telescope (right) and medium-resolution package (left) are seen here in assembly and testing. Credit: NASA
Scientists expect the materials thrown out of the freshly bored hole will settle within a few minutes, permitting good visibility into the crater. The mothership has less than 14 minutes to make its observations while zooming toward the comet before passing by Tempel 1 at a distance of 300 miles. The craft enters a "shield mode" to protect itself from the powerful sandblasting during flight through the coma at closest approach.
"Our baseline is it will take 200 seconds to form the crater, but uncertainties in the density of the nucleus - something that we just don't know - the crater could take as long as 600 seconds to form. This was one of our mission design problems, making sure we had long enough interval to observe so that we make sure the crater finished forming before we flew by but keeping the interval small enough that we weren't so far away at the time of impact that we had no resolution. This what led us to the 800-second window between impact and the going into our shield mode through the innermost coma," A'Hearn said.
"The biggest uncertainty in the mission is what the phenomena will be at the time of impact. And that is because there are many different ideas in the scientific community about the nature of the cometary nucleus.
"There are some people in the community who think the nuclei are strong and that we will have an ejecta cone that leaves the nucleus entirely. We think the cone will stay attached to the nucleus and the crater will be controlled by gravity.
"Other people think we will fracture the nucleus into several pieces, other people think we may just compress material downward and not eject anything outward, or almost nothing outward," A'Hearn said. "It is this uncertainty in the predictions, or the wide range of predictions, that makes it particularly important to do this conceptually very simple experiment."
one shot at grabbing scientific data on the primordial material packed inside the comet.
"We do maps across the nucleus after the impact to try and get spectra of the crater floor, see how different it is from the neighboring terrain that is undisturbed," A'Hearn said. "We take some spectra off the limb to look at the gases that are coming out of the crater. As we get very close, we actually have to let the camera drift a little and take a couple of images to make sure we get crater in the high-resolution camera."
What might the craft see down in the crater?
"My guess is if we excavate more deeply, we will see more carbon dioxide and carbon monoxide, dry ice vaporizing instead of water ice vaporizing," A'Hearn said. "The more volatile ices have been depleted in the surface layers. That's the kind of signature that we're looking for, to see how that composition changes."
About 50 seconds before closest approach, the flyby craft orients itself with protective shielding guarding against a destructive hit by comet dust.
"We've designed extra shielding on certain parts of the spacecraft. So when I say it turns to shield mode, what that means is it actually places those shields in the direction of the cometary dust and debris. That is meant to protect the spacecraft itself from any particle hits. That shielding was designed based on what we know today of probable particle sizes, distribution and density at that distance from the comet," Grammier said.
Despite the added protection, the mothership will be relaying its pictures and information to Earth live in case the craft doesn't survive the encounter to tell the tale afterward.
"There are worries, that is why we are transmitting as much as we can in real-time, as much as the communications system will allow us to," A'Hearn said. "The engineers have predicted that the probability of a fatal hit is down at the one or a couple percent level, given the amount of shielding we have."
Once through the dangerous region, the departing mothership maneuvers to observe the comet's back side a quarter-hour after closest approach.
"We fly through the innermost coma, fly through the orbital plane and then turn around and look back... to take images of the other side. When we take pictures of the other side, the crater itself will be hidden, but we will still be looking to see if we can see ejecta from the crater. A likely scenario is that after we make the crater, there will be a lot spontaneous outgasing from the floor of the crater because there is very volatile ice near the surface that used to be buried deeply. There is a reasonable chance that we would see a new jet in the coma coming from the crater - and we would see it where it comes out from behind the limb of the nucleus," A'Hearn said.
"We also use these look-back images to figure out the three-dimensional shape of the nucleus since we don't get to see a full rotation. We do the look-back monitoring for up to a day after impact."
http://spaceflightnow.com/delta/d311/images/trajectory.jpg
Deep Impact launches in January and slams its impactor into Comet Tempel 1 in July. Graphic: Mark McLellan/Astronomy Now
Ground-based telescopes in Hawaii will have prime viewing with the comet high in the sky at the time of impact, while the southwestern U.S. and Baja California will have Tempel 1 low in the sky. But a global campaign is underway to provide thorough monitoring of the comet before and after the collision with special imaging techniques.
"We may create this new jet that may persist for hours or days or weeks or even months. So we are looking for observations afterwards," A'Hearn said.
"We are trying to get complete longitude coverage so we can monitor the comet continuously from something like four days before the impact - two rotation periods - until a week after the impact."
"At the time of encounter, we may be able to see a bright flash of light momentarily," Meech said. "But the main part that we're going to be looking for from the ground will be some of the long-term effects. For example, as the dust from this newly excavated crater starts to flow away from the comet, it will take many days to spread...and form a nice dust tail.
"Ground-based observations with a wide-angle field of view can best watch the tail develop. In addition, we will get to look at wavelength regions we won't have on the spacecraft and can look for molecules coming outside from the nucleus, different types of molecules. We're hoping to see a change in the chemistry after the impact as compared to pre impact.
"So there will be a lot of exciting science...at various observatories all over the world," she said. "Basically, everybody's going to be able to participate."
The impact will have no detectable influence on the comet's orbit around the sun, scientists say.
"The comet is so large and the spacecraft is so small that it's sort of like an 18-wheeler running over a gnat," Yeomans said.
The mission follows NASA's Stardust project that flew past Comet Wild 2 last January, catching dust particles for return to Earth in 2006. The European Rosetta mission is currently flying to Comet Churyumov-Gerasimenko where a tiny lander will be dispatched to the frigid nucleus.
If the Deep Impact mothership remains in good health, NASA could route the craft to other comets for close-up imaging by the onboard cameras, A'Hearn said.
Fico.
Ma con la fortuna che ho addosso ultimamente, se lanciano un cd con su il mio nome, quello torna giù... cometa compreso! :D
625,000 Names to be Vaporized in Deep Impact
By Bjorn Carey
Staff Writer
posted: 30 June 2005
7:00 am ET
The names of more than 600,000 people will be part of the fireworks July 3-4 when Comet Tempel 1 collides with the Deep Impact impactor spacecraft.
When Deep Impact was in its final stages of development, organizers in NASA's Education and Public Outreach program created the Send Your Name to a Comet campaign. The Internet-based effort allowed participants to sign their name up for destruction and print out an official certificate documenting their place on the list.
"We thought it would be fun for people to say their name was on the impactor that collided with the comet," organizer Maura Roundtree-Brown told SPACE.com. "We thought it would let them feel like they were part of the mission."
Although people could submit their names between May 2003 and January 2004, a large number waited until the last minute to sign up.
"In the end they were trying to sign up so fast that it was almost more than the system could take," Roundtree-Brown said. "In all we got about 625,000 names. It was a surprise."
Once registration closed, the list was burned onto a mini-CD and attached to the spacecraft -- tucked under the thermal blanketing to make sure no harm could come to it.
No amount of thermal blanketing will protect the CD on this holiday weekend when the impactor and comet slam together at 23,000 mph.
"It will be vaporized along with the impactor," Roundtree-Brown said.
Been Done Before
The Stardust mission, which sent a spacecraft to collect close-up data on comet Wild 2, also carried a list of names. That list will return to Earth in one piece.
At least one group of names on the list will be eagerly watching the sky, waiting for impact. Dee McLellan's seventh grade class at the Meadow Creek School in Andover, Minnesota did a special Deep Impact math project.
McLellan designed a class project where her students collected an amount of pennies equivalent to the mass of the impactor's copper tip -- about 300 pounds. That's a lot of pennies -- around 50,000 -- and the whole town helped the kids come up with the total.
By the end of the project, the students had raised $500, which they donated along with school supplies to their sister school in the Ukraine.
"The first we heard about it was that the class contacted us asking how much of the total mass of the impactor was copper," Roundtree-Brown said. "The exciting and successful thing for us as an outreach project is when it goes out of our hands to teachers and students and, in this case, a whole community."
While NASA will have to wait until Monday to see if they hit the mark with their impactor, Roundtree-Brown is pleased with the way the Send Your Name to a Comet campaign turned out.
"I was surprised how many people sent us emails and said that being able to submit their names to the impactor made them feel like they were part of the mission," Roundtree-Brown said. "And that's why we did it -- because it would be fun for people to be connected to the mission."
Questa volta potrò dire, io c'ero :D
io alla fine non l'ho fatto perchè ho pensato che porterà sfiga!
:read:
io alla fine non l'ho fatto perchè ho pensato che porterà sfiga!
:read:
quindi se qualcosa va storto è colpa mia? :stordita: :D
Deep Impact fires its bullet at Comet Tempel 1
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 3, 2005
PASADENA, Calif. (CBS) - NASA's Deep Impact probe released a compact, instrumented smart bomb Sunday, a copper-clad robotic kamikaze programmed to place itself in the path of a speeding comet early Monday for a scientifically spectacular 23,000-mph Fourth of July collision.
http://spaceflightnow.com/delta/d311/images/deepimpact.jpg
An artist's concept shows the Deep Impact mothership releasing its copper laden impactor at Comet Tempel 1. Credit: NASA/JPL
Releasing the energy equivalent of 4.5 tons of TNT, the 820-pound "impactor" spacecraft, blasting through comet Tempel 1's dark crust and into its icy interior, is expected to blow out a crater that could be as small as a house or as large and deep as a football stadium.
Either way, the crater and the cloud of debris blown back out into space will give scientists their first glimpse into a comet's hidden interior and in so doing, open a new window on the birth of the solar system.
"Deep Impact will provide the most detailed pictures we've ever seen of a comet," said Lindley Johnson, Deep Impact program executive at NASA headquarters. "But instead of just looking at the surface of the comet, it's actually going to plunge in and blow out the material so we can see what's inside."
Said Jessica Sunshine, a co-investigator with Science Applications International Corp.: "Like any good geologist, we take our hammer and we hit it and find out how strong it is and what it's made out of on the inside. ... Literally, these materials have not seen the light of day in 4.6 billion years."
Launched Jan. 12, the $333 million Deep Impact mission entered its final stages at 2:07 a.m. Sunday (11:07 p.m. PDT Saturday) when radio signals confirmed release of the impactor spacecraft some 500,000 miles from Tempel 1.
Twelve minutes after release, the Deep Impact mothership, known as the flyby spacecraft, carried out a 14-minute thruster firing to change its velocity by nearly 230 mph, putting it on a course that ultimately will carry it below and then behind the comet.
Both spacecraft were reported to be in good health after the make-or-break maneuvers, setting the stage for impact at 1:52 a.m. Monday (10:52 p.m. PDT Sunday).
Instruments aboard the flyby spacecraft will watch the crash from a distance of some 5,348 miles - far enough to eliminate any threat of comet dust or crater debris. It also will relay pictures and telemetry from the impactor back to the Jet Propulsion Laboratory before skimming just 300 miles or so below the comet at closest approach 14 minutes after impact.
"If all goes well, the impactor spacecraft will be taking images all the way in to the point of impact, sending those images back to the flyby spacecraft, providing us with some of the most astonishing pictures of a comet ever taken," said mission manager Dave Spencer."
But getting those pictures will be challenging to say the least.
Tempel 1 is barreling through space at some 66,880 mph. Released almost directly in front of the comet on a near-miss trajectory, the impactor was moving at roughly 49,000 mph. Navigating autonomously, the impactor was programmed to make up to three maneuvers during its final two hours of life to position itself so the comet runs it down at a relative velocity of 23,000 mph.
"This is a tremendously exciting, daring first-of-a-kind mission to impact the nucleus of a comet," said project manager Rick Grammier. "What makes it daring and exciting also makes it extremely difficult and challenging from a technical and orchestration viewpoint. Let me give you an analogy of what this mission is like. It's a bullet trying to hit a second bullet with a third bullet at the right place and the right time watching the first two bullets and gathering the scientific data from that impact. That is extremely challenging."
Monte Henderson, deputy program manager with spacecraft-builder Ball Aerospace and Technologies Corp., said not even a right-stuff fighter pilot could pull off the flying challenge faced by the two Deep Impact spacecraft. As a result, both were programmed in advance to collect their own navigation data and to maneuver autonomously as required.
"These two spacecraft have been designed to accomplish something the best fighter pilots in our country would not be able to do," Henderson said. "The primary challenge of this mission - two spacecraft independently locating an illuminated area on the comet, the impactor flying itself into the lit area and impacting the comet while the flyby diverts itself out of the path of the comet and images that same lit area to watch the encounter and the resulting crater formation and debris field - is something that could not be accomplished using human reflexes and human vision. So we had to design a navigation and control system that would allow the flyby and the impactor spacecraft to perform this very intricate ballet."
The collision will change the comet's velocity by a barely noticeable 014 inches per hour. It will change the time needed for one orbit by less than one second and raise the low-point of the comet's orbit by about 33 feet. A NASA press kit says the collision will be similar to that of a 767 jet airliner running into a mosquito.
Data from the impactor and the mothership will be transmitted to Earth in realtime. For redundancy, a complete set of data also will be recorded on board the mothership for later transmission.
Eighty-three million miles away, NASA's Hubble Space Telescope, the Spitzer infrared telescope, the Chandra X-ray Observatory and some 60 ground-based telescopes in 20 countries will study the impact in a variety of wavelengths. The giant 33-foot Keck telescopes and others in Hawaii will have ringside seats for the blast, which will occur in darkness over the south Pacific Ocean.
While visible, in theory, to the unaided eye from the southwestern United States, "you won't be able to see it with the naked eye, most likely," Grammier said. Even with a telescope, "we expect that the flash of the impact will be very momentary so you need to be trained on the comet at the time. Obviously, we expect the observatories ... to see it because they'll be watching for it."
Here is a timeline of upcoming events (all times in EDT):
TIME...........EVENT
July 3
02:00 p.m......Pre-impact news briefing/update
03:00 p.m......Flyby diversion trim maneuver
05:45 p.m......Ephemeris update
11:30 p.m......NASA television coverage begins
11:53 p.m......Start impactor auto-navigation imaging
July 4
12:21 a.m......Impactor trajectory maneuver No. 1
01:17 a.m......Impactor trajectory maneuver No. 2
01:39 a.m......Impactor trajectory maneuver No. 3
01:52 a.m......Impact
02:05 a.m......Flyby reorients to shield mode for close approach
02:06 a.m......Flyby closest approach
02:51 a.m......Flyby first post-impact image
04:00 a.m......Post-impact news briefing on NASA TV
02:00 p.m......Deep Impact news conference on NASA TV
Comet 9P/Tempel 1 was discovered in 1867 by Ernst Wilhelm Leberecht Tempel, a German-born astronomer who was searching for comets from Marseilles, France. Tempel 1 orbits the sun between Mars and Jupiter, taking 5.5 years to complete one revolution. Based on very limited observations, scientists believe the slightly elongated nucleus is roughly 3.7 miles across.
Deep Impact co-investigator Donald Yeomans, a comet expert at the Jet Propulsion Laboratory, described the comet as a "jet-black pickle-shaped icy dirtball the size of Washington DC."
Tempel 1 was chosen for the Deep Impact mission because it is reachable in the mission timeframe, the nucleus is fairly large and thus relatively easy to hit and its orbit allows the impact to occur on the sunlit side.
Tempel 1 originated in the Kuiper Belt, a wide flattened disk of icy debris extending from the orbit of Neptune to well beyond Pluto. Perturbed by gravitational interactions, primarily involving Jupiter and Saturn, a Kuiper Belt comet can fall into the inner solar system and become captured in a so-called short-period orbit.
In the early solar system, gravitational encounters also threw large numbers of comets into a vast, spherical shell known as the Oort Cloud. Comets that eventually fall back into the inner solar system from the Oort Cloud typically have orbits measured in millions of years.
"Comets formed in the outer part of the solar system and preserve clues to its formation," said principal investigator Michael A'Hearn. "They formed from Jupiter on out to beyond Neptune four-and-a-half billion years ago, together with all the planets. The inner ones got ejected to the Oort Cloud, which extends halfway to the next star, whereas the ones that formed in the Kuiper Belt are probably still in the Kuiper Belt.
"We are examining comets that come in from the Kuiper Belt with Deep Impact. The problem in understanding the comets is, each time the comet goes close to the sun, the surface layer gets heated and this changes the surface layers. So it's only the interior that preserves the clues to the formation of the solar system."
Some models hold that cyclic solar heating affects only the top foot or so of a comet's crust. Other models hold that surface evolution extends to much greater depths.
"A related question is, we know comets eventually stop out-gassing," A'Hearn said. "Why is this? is this because they've exhausted all the gas in the interior, all of the ices have evaporated, all the gasses have flown out? Or is it because the surface layer has developed some sort of a crust of organic goo or just overbearing materials that prevents the ice inside from evaporating and escaping as gas."
By studying the shape of the cone of debris released by the impact, scientists will gain additional insights.
"The biggest uncertainty in the mission is what the phenomena will be at the time of impact," A'Hearn said. "And that is because there are many different ideas in the scientific community about the nature of the cometary nucleus.
"There are some people in the community who think the nuclei are strong and that we will have an ejecta cone that leaves the nucleus entirely. We think the cone will stay attached to the nucleus and the crater will be controlled by gravity.
"Other people think we will fracture the nucleus into several pieces, other people think we may just compress material downward and not eject anything outward, or almost nothing outward," A'Hearn said. "It is this uncertainty in the predictions, or the wide range of predictions, that makes it particularly important to do this conceptually very simple experiment."
If all goes well, Deep Impact will answer those questions, and more.
Depending on the strength of the nucleus, A'Hearn expects the impactor to blast a crater at large as a football stadium or as small as an average home. If the cloud of dust normally surrounding the comet is relatively thin, the last image taken by the impactor's 4.7-inch telescope, at an altitude of 12 miles or so, will show details as small as 8 inches across. If the dust is thicker, the camera's optics will be sand-blasted earlier and the final image would be snapped from a higher altitude, reducing resolution to 10 feet or so.
For comparison, the European Space Agency's Giotto probe could not distinguish surface features on Halley's comet smaller than about 300 feet across - the size of a football field.
"Our mission, the Deep Impact mission, is going to resolve objects on the surface (of Tempel 1) about the size of the football," said Yeomans. "So we're making a huge leap forward in resolution."
The ejecta cone will be observed in detail by the mothership's 11.8-inch high-resolution instrument, or HRI, the large telescope that delivers magnified images to a multi-spectral camera and an infrared spectrometer. Once within 420 miles of Tempel 1, the HRI should achieve a resolution of six feet per pixel.
A medium-resolution instrument aboard the mothership features a 4.7-inch telescope, identical to the one on the impactor, to provide a wider field of view with a maximum resolution of about 33 feet per pixel. The MRI will observe the entire crater and surrounding territory while the HRI focuses on small areas of the crater's interior.
The instruments will photograph the collision, the resulting crater and analyze light reflected from the dust blown back into space to characterize its chemical composition.
"The ejecta in the case of a big crater, will be comparable to what the comet normally releases over the period of about five days," A'Hearn said. "And it will all come out in four or five minutes. An optimistic assumption is ... sunlight reflecting off that dust will be visible to the naked eye from Earth. The pessimistic assumption is the comet is very strong.
"When you get the small end of the cratering ... then you don't get nearly as much ejecta," he said. "The key observation is to look at the ejecta cone and see if it grows wider and wider and stays attached to the nucleus or does it lift off?"
The former implies a low-density, gravity-dominated nucleus while the latter implies a nucleus that includes some sort of bonding agent to give the material strength.
As for what the mothership's instruments might see peering down into the crater, "my guess is if we excavate more deeply, we will see more carbon dioxide and carbon monoxide, dry ice vaporizing instead of water ice vaporizing," A'Hearn said. "The more volatile ices have been depleted in the surface layers. That's the kind of signature that we're looking for, to see how that composition changes."
The mothership will have less than 14 minutes to collect the impact data before it turns away, re-orienting itself into a protective position to prevent damage as it flies through the thicker regions of the dust cloud surrounding the nucleus.
"These two spacecraft are the armored Humvees of deep space experiments," Henderson said. "They're smart and they're tough. We have the potential to encounter significant debris as we're flying into the coma and the tail of the comet. So we have installed debris shields on both the flyby and the impactor spacecraft to protect ourselves from debris.
"Let's keep in mind the size of the debris we can protect against. We're traveling at 23,000 miles per hour and these shields were designed to stop particles up to a quarter of a gram, or one fourth the size of an M&M. All of our models and the data we've received from previous flyby missions tells us we're going to be fine. But certainly for the impactor, it's going to be a very bumpy ride as it gets closer and closer to the comet."
Once safely past the nucleus, the flyby spacecraft will turn again to take a final few photographs of the crater and the ejecta cone and to transmit its stored data to Earth. The impact should make quite a splash, at least for space-based and large ground-based telescopes like those atop Mauna Kea, Hawaii.
"At the time of encounter, we may be able to see a bright flash of light momentarily," said Karen Meech, a Deep Impact science team member. "But the main part that we're going to be looking for from the ground will be some of the long-term effects. For example, as the dust from this newly excavated crater starts to flow away from the comet, it will take many days to spread ... and form a nice dust tail.
"Ground-based observations with a wide-angle field of view can best watch the tail develop. In addition, we will get to look at wavelength regions we won't have on the spacecraft and can look for molecules coming outside from the nucleus, different types of molecules. We're hoping to see a change in the chemistry after the impact as compared to pre impact.
"So there will be a lot of exciting science ... at various observatories all over the world," she said. "Basically, everybody's going to be able to participate."
CONFITEOR
04-07-2005, 03:48
Nasa: al via missione Deep Impact, attacco alla cometa
PASADENA (California) - Dovrebbe avvenire intorno alle 7.50 di oggi, 4 luglio, ora italiana, la missione della Nasa Deep Impact che consiste nel far esplodere una parte della cometa Tempel-1 con una sonda-missile, per studiarne l'interno. Secondo l'ente spaziale americano non dovrebbe esserci alcun rischio di una modifica sostanziale di Tempel-1 e di una collisione futura fra la cometa e la Terra, anche se un'astrologa russa, Marina Bai, ha denunciato la Nasa per l'esperimento, considerato un "attentato allo stato naturale dell'Universo". La missione, secondo la studiosa, distruggerebbe l'equilibrio del Cosmo. (Agr)
CONFITEOR
04-07-2005, 03:49
3 luglio 2005 (17:40) - Ormai giunta al penultimo dei 172 giorni di viaggio verso la cometa Tempel 1, la sonda della NASA Deep Impact ha effettuato con successo il distacco del suo impactor alle 8:07 (ora italiana) di stamani. Al momento del rilascio, l’impactor si trovava a circa 880.000 km dalla sua preda.
La separazione tra la sonda-madre e l’impactor, un proiettile di rame delle dimensioni di una lavatrice, è stata soltanto una delle fasi essenziali che porteranno all’incontro programmato con la cometa per le 7:52 di domattina.
Sei ore prima del rilascio dell’impactor, la sonda Deep Impact aveva completato anche la sua quarta manovra di correzione della traiettoria (v. ASTROnews Le fasi finali). L’accensione dei motori, durata 30 secondi, ha modificato la velocità della sonda di circa 1 km/h. L’obiettivo della manovra era di portare l’impactor il più possibile vicino al percorso diretto della sopraggiungente cometa Tempel 1. [L’impactor sarà infatti “investito” dalla cometa, ndt]
Poco dopo il completamento della manovra, gli ingegneri dell’impactor hanno iniziato a prepararlo al distacco. Le batterie sono state attivate alle 7:12 di stamani. L’impactor infatti non dispone di pannelli solari; le batterie del veicolo forniranno tutta l’energia di cui ha bisogno per la sua breve vita di un giorno.
Per rilasciare l’impactor sono state azionate cariche esplosive, le quali hanno liberato una molla che ha separato le due sonde ad una velocità di circa 35 cm al secondo.
Ora che la Tempel 1 sta accorciando rapidamente le distanze con l’impactor procedendo nella sua direzione a 10 km al secondo (36.000 km/h), non resta molto tempo al personale di controllo di missione per contemplare il proprio lavoro. Dodici minuti dopo la separazione, la sonda madre ha iniziato una manovra diversiva di 14 minuti, che ha rallentato la sua velocità relativa all’impactor di 102 m al secondo, spostandola così dalla traiettoria del nucleo della cometa in arrivo e preparando il terreno per un posto in prima fila per i fuochi d’artificio celesti che cominceranno fra poche ore.
Il controllo di missione ha confermato che l’antenna in banda S sta comunicando correttamente con la sonda madre. Tutti i dati dall’impactor, comprese le attesissime immagini del suo tuffo finale nel nucleo della cometa, saranno trasmesse alla sonda e rinviate da questa alle antenne del Deep Space Network che saranno in ascolto a 134 milioni di km di distanza.
Mentre tutto sembra andare come previsto per Deep Impact, anche la cometa sta preparando uno show. Il nucleo della cometa, lungo 14 km, ha mostrato un altro outburst, un aumento nell’emissione di gas e polveri, il 2 luglio alle 10:34 (ora italiana) quando una massiccia espulsione di ghiaccio e altre particelle ha temporaneamente aumentato le dimensioni e la luminosità della nube (coma) che circonda la cometa.
L’outburst del 2 luglio è il quarto osservato nelle scorse tre settimane. I precedenti tre, anche se sembrano aver avuto origine sempre nella stessa area del nucleo, non sarebbero avvenuti ogni volta quando questa era rivolta verso il Sole.
“La cometa è stata certamente ricca di sorprese e probabilmente ne ha in serbo altre per noi” ha detto il project manager di deep impact Rick Grammier del Jet Propulsion Laboratory della NASA. “Nessuno di questi eventi, tuttavia, ci preoccupa o ci ha costretto a cambiare il nostro piano di missione”.
Fonte: JPL/NASA Press Release 2005-108
CONFITEOR
04-07-2005, 04:00
Roma, 3 lug. (Adnkronos) - Domani, all'alba, nello spazio profondo si giocherà una nuova sfida dell'uomo alla scoperta delle origini del sistema solare. O almeno, così, sperano gli scienziati della NasaUn proiettile da 370 chili, sparato alla velocità di 37mila chilometri orari (pari un viaggio da New York a Los Angeles in meno di sei minuti e mezzo) dalla sonda Deep Impact della Nasa, trafiggerà la cometa Tempel 1 per arrivarle al 'cuore' e tentare di svelare così i tanti misteri delle stelle con la coda. La collisione del modulo Impactor, sganciato questa mattina (alle 2.07 a.m. Edt), è previsto alle ore 8.00 ora italiana (1.52 a.m. Edt) di domani 4 luglio, giorno in cui si celebra in America l'Independence Day. Ed il proiettile, completamente rafforzato con rame, colpirà la Tempel 1 creando un cratere grande come un campo di calcio e profondo come un palazzo di sette piani. Gli scienziati della Nasa sperano di poter studiare la materia di cui la cometa è composta sotto il suo nucleo ghiacciato, alla ricerca di tracce delle sostanze che risalgono all'origine delle galassie. Secondo gli esperti, infatti, le affascinanti quanto misteriose stelle con la coda portano al loro interno gli 'ingredienti' che hanno consentito non solo la formazione di stelle e pianeti ma anche dell'acqua e, quindi, della vita sulla Terra.
Al momento dell'impatto, la sonda si troverà a circa 500 chilometri dalla cometa e, con una sofisticata macchina fotografica, invierà in tempo reale al centro della Nasa immagini ravvicinate del nucleo della cometa.
La grande caccia alla cometa Tempel 1 è cominciata dalle paludi del Kennedy Space Center, in Florida. Qui, il 12 gennaio scorso alle 19.47 locali, si sono accesi i razzi del gigantesco Delta 2, utilizzato per mettere in orbita la sonda con un mandato da 'missione hollywoodiana' fin dal nome Deep Impact, come il titolo di un film del 1998 con Bruce Willis, improvvisato astronauta spedito nello spazio per distruggere una cometa che minaccia la terra.
"La parte più difficile e la sfida maggiore sarà l'incontro vero e proprio, perché stiamo facendo cose che non sono mai state fatte prima", aveva detto subito dopo il lancio della sonda Jay Melosh, un geologo planetario dell'Università dell'Arizona che fa parte del team della Nasa che ha messo a punto la straordinaria missione. Secondo quanto spiegato in una recente intervista da Michael A'Hearn, esperto dell'Università del Maryland che segue e supervisiona la missione, "nelle 24 ore successive all'impatto si mostreranno agli studiosi i più spettacolari fenomeni scientifici nella storia della scienza cometaria". "Con le informazioni che riceveremo dopo l'impatto si aprirà un nuovo scenario -ha detto A'Hearn-, conosciamo così poco sulle strutture del nucleo delle comete che ogni momento aspettiamo di scoprire qualcosa di nuovo". A'Hearn, inoltre, ha sottolineato che a seguito dell'impatto "gli scienziati dovranno osservare come si formano i crateri, misurarne la profondità e il diametro oltre alla composizione interna. Fondamentale sarà la possibilità di studiare la composizione della cometa al di sotto della superficie ghiacciata per rispondere a importanti questioni riguardo la formazione del sistema solare".
Ma nonostante il fascino e l'importanza dell'impatto, la collissione spaventa alcuni scienziati perplessi per il danno che potrebbe provocare al grande corpo celeste. "La collisione del proiettile su Tempel 1 -assicurano però dalla Nasa- non provocherà particolari danni alla cometa, ma permetterà di dare un'occhiata sotto la superficie della stessa, dove il materiale non è cambiato molto dal momento della formazione del sistema solare".
Dunque è tutto pronto per il conto alla rovescia che vedrà in primo piano la cometa che deve il nome al suo scopritore, il francese Ernst Wilhelm Liebrecht Tempel. Lo scienziato la battezzò cosi' nell'aprile del 1867. E, da allora, ha fatto sorridere non poche volte gli astronomi a causa della sua "ironica forma a cetriolo".
Luther Blissett
04-07-2005, 07:06
Bum.
http://www.nasa.gov/images/content/121347main_confirmation-330.jpg
duchetto
04-07-2005, 08:52
non ci sono ancora foto scattate dalla navetta madre?
lunaticgate
04-07-2005, 09:04
Gli americani non sanno più a chi buttare missili e bombe ed adesso se la pigliano con le comete! :D
:stordita:
non ci sono ancora foto scattate dalla navetta madre?
Quella che ho postato cos'è? :stordita:
Gli americani non sanno più a chi buttare missili e bombe ed adesso se la pigliano con le comete! :D
:stordita:
Non era un missile :fagiano:
Per chi volesse seguire:
http://www.nasa.gov/mission_pages/deepimpact/main/index.html?msource=release289
duchetto
04-07-2005, 09:32
Quella che ho postato cos'è? :stordita:
credevo fosse una foto dall'impactor :stordita:
credevo fosse una foto dall'impactor :stordita:
Veramente è la foto dell'impatto... :D
duchetto
04-07-2005, 10:25
speravo in immagini più nitide...abituato alle risoluzioni di opportunity e spirit..
interessante questa foto dall'Hubble
http://www.nasa.gov/images/content/119326main_tempel1_hst_062705_516.jpg
Però se non ricordo male quella foto riporta un fenomeno naturale della cometa, non l'impatto...
duchetto
04-07-2005, 11:12
Però se non ricordo male quella foto riporta un fenomeno naturale della cometa, non l'impatto...
si hai ragione
Hubble photos of comet Tempel 1
In a dress rehearsal for the rendezvous between NASA's Deep Impact spacecraft and comet 9P/Tempel 1, the Hubble Space Telescope captured dramatic images of a new jet of dust streaming from the icy comet.
The images are a reminder that Tempel 1's icy nucleus, roughly half the size of Manhattan, is dynamic and volatile. Astronomers hope the eruption of dust seen in these observations is a preview of the fireworks that may come July 4, when a probe from the Deep Impact spacecraft will slam into the comet, possibly blasting off material and giving rise to a similar dust plume.
The two images, taken seven hours apart on June 14, show Tempel 1 and its new jet. The image at left, taken at 2:17 a.m. (EDT), is a view of the comet before the outburst. The bright dot is light reflecting from the comet’s nucleus, which appears star-like in these images because it is too small even for Hubble to resolve. The nucleus, a potato-shaped object, is 8.7 miles (14 kilometers) wide and 2.5 miles (4 kilometers) long. Hubble's viewing the nucleus is as difficult as someone trying to spot a potato in Salt Lake City from New York City.
The photo at right, snapped at 9:15 a.m. (EDT), reveals the jet [the bright fan-shaped area]. The jet extends about 1,400 miles (2,200 kilometers), which is roughly half the distance across the U.S. It is pointing in the direction of the Sun.
ma 10 m/s non sono pochi? un corpo che cade penso che vada molto + veloce di 36 km/h...
ma 10 m/s non sono pochi? un corpo che cade penso che vada molto + veloce di 36 km/h...
Dove li hai letti i 10 m/s?
NASA - Deep Impact Mission
Il cratere sarà scavato utilizzando la sola energia cinetica della sonda d'impatto, ben 19 Gjoules (pari a 4,8 tonnellate di TNT), generata dalla massa della sonda (370 kg) e dalla velocità di impatto (pressapoco 10,2 m/s).
[/b]
...
OT: gpc, PM incoming for you
...
OT: gpc, PM incoming for you
Ah, si sono dimenticati una k... :D
"At the moment the impactor was vaporizing itself in its 10 kilometers per second (6.3 miles per second) collision with comet Tempel 1"
Per favore, potete dirmi se vi funziona questo link?
http://photojournal.jpl.nasa.gov/catalog/PIA02122
E' una settimana ormai che non riesco ad accedere al sito photojournal...
These pictures of comet Tempel 1 were taken by NASA's Hubble Space Telescope. They show the comet before and after it ran over NASA's Deep Impact probe.
http://img287.imageshack.us/img287/3825/pia02122modest9zq.th.jpg (http://img287.imageshack.us/my.php?image=pia02122modest9zq.jpg)
Non funziona.
Benissimo :muro:
Deep Impact is a smashing success
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 4, 2005; Updated: 5:45 a.m. EDT
PASADENA, Calif. (CBS) - A scientific smart bomb crashed into Comet Tempel 1 early today, blasting a sparkling shower of icy debris into space in a 23,000-mph Fourth of July spectacular 83 million miles from Earth.
http://spaceflightnow.com/deepimpact/images/050704deepimpact.jpg
This image shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel 1 at 1:52 a.m. EDT. The picture was taken by the mothership's medium-resolution camera 16 seconds after impact. Credit: NASA/JPL-Caltech/UMD
"Jeez, and we thought it was going to be subtle!" marveled comet expert Donald Yeomans as images of the impact were received at the Jet Propulsion Laboratory. "We've had a far bigger explosion than we anticipated. ... I can't imagine how this could go any better."
Said Rick Grammier, the Deep Impact project manager: "It came together quite well, just phenomenal. It went very much like clockwork. We didn't exercise a single contingency plan."
As it closed in on Tempel 1 at 11 times the speed of a rifle bullet, the impactor beamed back a stream of ever more detailed pictures, showing circular craters, plain-like areas, a long, snaking ridge and jumbled-looking terrain similar to regions on the moon.
"It's illuminating some extremely interesting surface features," Yeomans said, describing the pictures as they as they came in. "That's going to keep the scientists going for a long time. The navigation was perfect, it couldn't have been any better. The impact was bigger than I expected, bigger than most of us expected. So this is going to tell us a great deal about how this comet is put together."
The 820-pound impactor spacecraft, programmed to place itself directly in the comet's path, collided with Tempel 1 at 1:52 a.m. EDT (10:52 p.m. PDT Sunday), releasing the energy equivalent of 4.5 tons of TNT as it vaporized in a sudden, spectacular flash.
Looking on 5,250 miles away, the Deep Impact mothership that ferried the impactor to Tempel 1 trained two telescopes and an infrared spectrometer on the impact site, studying the subsurface ices blown into space by the collision.
The crater that almost certainly resulted from the impact was not immediately visible in an obscuring cloud of debris that spread outward into deep space like some ghostly fog.
"Obviously, it was a very big impact," principal investigator Michael A'Hearn said at a post-impact news conference. "Presumably, we have a large crater in one of those images that hasn't played back yet.
"Interpreting the ejecta cone ... is going to take a bit of time. There's a lot of structure in it that's of interest to understanding the nature of the comet. We'll be working that over the next half day and weeks and months and years. I just look forward to a wealth of data that will take me to retirement."
While he provided no details, A'Hearn said flyby craft's infrared spectrometer captured clear chemical signatures of various icy compounds including some that were clearly unexpected.
During the final stages of the encounter flight controllers frequently gasped and broke out in repeated cheers as more detailed images rolled in from space.
"I'm at a loss to explain just how on Earth our little washing machine-sized impactor caused such a disturbance some 83 million miles away," said the normally unflappable Yeomans.. "This is going to take some work to explain, but it's sure taken me by surprise. And I suspect some of my colleagues up in the science area are equally surprised."
The flyby spacecraft had just 13 minutes to collect and transmit its highest-priority data before re-orienting itself, bringing protective dust shields to bear as it fell behind the comet, passing just 300 miles below the Washington, DC-size nucleus at closest approach.
About 27 minutes later, the flyby craft turned back toward the receding comet for additional observations, surviving its close flyby of Tempel 1 in near-perfect health. By then, A'Hearn said, the expanding ejecta cone was larger than the nucleus of the comet and still evolving.
Back on Earth, meanwhile, astronomers in virtually every major observatory in the world with a view of the collision aimed their telescopes at Tempel 1 to monitor the flash of the impactor's destruction.
The Hubble Space Telescope, the Spitzer Infrared Telescope and the Chandra X-Ray Observatory also monitored the collision from Earth orbit. Hubble measured a two-magnitude increase in light output, corresponding to about a six-fold jump in brightness. Before-and-after images from Hubble showed a distinct brightening with a fair amount of structure in the debris cloud.
Tempel 1 was just above the southwestern horizion for observers in the extreme western United States, but it was not immediately known how many amateurs might have been able to detect the sudden brightening that signaled the impactor's crash.
But it was the flyby spacecraft that had the best seat in the house, making its own observations while relaying final close-up images from the impactor taken just a few minutes before its kamikaze-like destruction.
In its final few shots, Yeomans estimated the impactor's camera was able to detect features as small as about eight inches across. The final picture was snapped just 3.7 seconds before impact. For comparison, the European Space Agency's Giotto probe was unable to detect features on Halley's Comet in 1986 smaller than about the length of a football field.
To give the small impactor enough mass to excavate a significant crater, it was loaded with enough copper to make 45,000 pennies. Copper was chosen for the bulk of the impactor's mass because it is not present in comets, allowing astronomers to ignore the remains of the spacecraft in spectroscopic studies of the resulting debris cloud.
While it will take time to fully analyze the downlinked data, astronomers almost certainly will learn more than enough to re-write their textbooks about cometary structure and evolution. On a more fundamental level, the $333 million Deep Impact mission will shed light on the composition of the cloud of gas and dust that coalesced to form the solar system 4.6 billion years ago.
And while it was not a primary goal of the mission, the deep space fireworks display will give scientists and engineers valuable insights into what might be needed someday to divert or destroy a comet on a collision course with Earth.
"It's considerably brighter, there's considerably more material coming off than I thought," Yeomans said, watching the initial impact images come in. "The predictions on the science team were all over the map. Someone won a fairly large-size pool here with a long-shot prediction of a rather extraordinary impact.
"We've got an object the size of a washing machine going in here creating a crater and ejecta that's just enormous. At least that's the way it looks like now. ... One of our science team members actually predicted the impact would release sub-surface pressure and we'd have a far bigger explosion than they anticipated. That may be what happened, I don't know."
Deep Impact was launched from Cape Canaveral, Fla., Jan. 12. The impactor was released from the flyby spacecraft early Sunday, roughly 24 hours before the collision, at a point in space about 500,000 miles in front of Tempel 1.
As the much-faster comet overtook the two spacecraft, a steady stream of images was transmitted to Earth, revealing more and more surface detail as the distance between the hunters and their quarry closed.
The final few pictures were quickly assembled into a sort of stop-action movie, showing the nucleus grow from a small, unfocused blur of light to a sharply defined, cratered body with a wealth of surface detail.
Tempel 1 originated in the Kuiper Belt, a broad flattened disk of icy debris extending from the orbit of Neptune to well beyond Pluto. Disturbed by gravitational interactions, primarily involving Jupiter and Saturn, a Kuiper Belt comet can fall into the inner solar system and become captured in a so-called short-period orbit.
In the early solar system, gravitational encounters also threw large numbers of comets into a vast, spherical shell known as the Oort Cloud. Comets that eventually fall back into the inner solar system from the Oort Cloud typically have orbits measured in millions of years.
"Comets formed in the outer part of the solar system and preserve clues to its formation," said A'Hearn. "They formed from Jupiter on out to beyond Neptune four-and-a-half billion years ago, together with all the planets. The inner ones got ejected to the Oort Cloud, which extends halfway to the next star, whereas the ones that formed in the Kuiper Belt are probably still in the Kuiper Belt.
"We are examining comets that come in from the Kuiper Belt with Deep Impact. The problem in understanding the comets is, each time the comet goes close to the sun, the surface layer gets heated and this changes the surface layers. So it's only the interior that preserves the clues to the formation of the solar system."
One reason for the current interest in comets is the believe they may have played a major role in the development of Earth's biosphere.
"In terms of their relationship with life, they may well have brought the water and carbon-based molecules to the early Earth that allowed life to form," Yeomans said in an interview for the author's book "Space Odyssey: Voyaging Through the Cosmos." "Subsequent collisions may have punctuated the evolution, wiped out the dinosaurs 65 million years ago and so allowed only the mammals to move forward.
"So in a sense, we may owe our position atop the world's food chain to the fact that the dinosaurs checked out as a result of an impact. So I think there's an increased realization that comets and asteroids are not just the flotsam and jetsam of the solar system. They really are, next to the sun itself, probably the most important objects in terms of power over life."
Press Conference ora in corso:
http://www.nasa.gov/ram/35037main_portal.ram
duchetto
04-07-2005, 20:52
una curiosità ,ma la collisione non ha prodotto nessun rumore?
Luther Blissett
04-07-2005, 21:12
una curiosità ,ma la collisione non ha prodotto nessun rumore?
...
una curiosità ,ma la collisione non ha prodotto nessun rumore?
io ho sentito qualcosina sta' mattina a dire il vero..... :D
una curiosità ,ma la collisione non ha prodotto nessun rumore?
Rumore nello spazio?? :confused: :mbe:
duchetto
04-07-2005, 21:52
Rumore nello spazio?? :confused: :mbe:
appunto
Luther Blissett
04-07-2005, 21:54
appunto
Appunto cosa?
Dai, l'hai sparata grossa.
duchetto
04-07-2005, 22:39
Appunto cosa?
Dai, l'hai sparata grossa.
ma io più che altro volevo una conferma, lo so che nello spazio non si propaga rumore,
vabbè lasciamo perdere :doh:
PaTLaBoR
04-07-2005, 22:41
inchia quanti genii
http://www.farzadsf1gallery.com/image_upload/tumbleweed.gif
Avete qualche link in italiano anche un pò ridotto, va bene uguale
http://www.repubblica.it/2005/g/sezioni/scienza_e_tecnologia/cometa/impatto/impatto.html
appena lo ritrovo vi posto il filmato dell' impatto dal punto di vista della sonda.
(se non è :old: )
http://www.nasa.gov/mov/121493main_Impactor%20POV%20to%20crash.mov
CONFITEOR
05-07-2005, 19:03
http://www.savonanotizie.it/foto/1701.jpg
Obiettivo: portare alla luce i segreti che si nascondono sotto la sua superficie in una missione mai tentata prima
Segnaliamo subito che è stato accennato a un aumento della luminosità della cometa "di circa 5 volte" (A'Hearn). In particolare, la luminosità sarebbe aumentata di tale valore nel corso delle prime due ore, per poi ridiscendere di circa due terzi. [Osservatori statunitensi avevano in mattinata riportato osservazioni di un repentino aumento di magnitudine, in grado - ad esempio - di rendere evidente la cometa, altrimenti osservabile soltanto con visione distolta.
La sonda è in ottima forma, la memoria è piena di dati che sono in fase di scaricamento a Terra. Ha ancora 160 kg di carburante disponibile. Nei prossimi giorni si deciderà se fare una extended missione o crearne una nuova.
Le immagini riprese da Deep Impact, riunite in un video, sono sensazionali. Si nota chiaramente un intenso flash iniziale; pochi istanti dopo uno sbuffo di materiale si espande rapidamente al di sopra dell'area di impatto, e solo successivamente un secondo sbuffo di materiale comincia a espandersi più lentamente dal punto di impatto, proiettando un'ombra sulla superficie.
La questione dei "due sbuffi" è fra quelle che ha maggiormente interessato gli scienziati presenti alla conferenza stampa: sembra essere una chiara indicazione - confermata da una delle numerose simulazioni realizzate in precedenza - che l'impactor ha attraversato prima una crosta superficiale di bassissima densità, incontrando poi improvvisamente un materiale molto più compatto che ha causato il secondo sbuffo di materia.
Un'altra caratteristica osservata è stata la distribuzione della temperatura sul nucleo prima dell'impatto. Le zone più spesso in ombra hanno una temperatura decisamente inferiore: ciò darà indicazioni utili per comprendere le proprietà termiche della cometa e contribuire a definirne meglio la composizione.
Altre nuove domande cui dare una risposta: già sulla cometa Borrelly erano state osservate delle zone piatte. Ora, anche su Tempel 1 sono state riscontrate alcune regioni dello stesso tipo. Il fenomeno che le ha originate non è ancora chiaro.
Non ci sono ancora immagini del cratere, che probabilmente sarà "ben più grande di una casa". Non ci sono soprattutto per la quantità di ejecta prodotti. Occorrerà almeno una settimana di lavoro per filtrare le immagini e riuscire a guardare attraverso gli sbuffi di materiale.
Fonte Unione Astrofili Italiani http://www.uai.it
CONFITEOR
05-07-2005, 19:04
Qualcuno sa dove trovare il video?
CONFITEOR
05-07-2005, 19:13
Il proiettile americano centra la cometa
Fuochi d'artificio nello spazio. La Nasa: «Un vero successo»
I fuochi d'artificio, questa volta, sono esplosi nello spazio. Il «proiettile» lanciato dalla Nasa a gennaio, la sonda «Deep Impact», ha centrato ieri, alle 7,52 ora italiana, la cometa «Tempel 1», provocando una deflagrazione pari a cinque tonnellate di tritolo nello spazio, a 133 milioni di chilometri dalla Terra. Un impatto tremendo, avvenuto alla velocità di 37 mila chilometri orari, che apre nuovi orizzonti alla ricerca spaziale. E che è stato definito dall'agenzia spaziale Usa «un vero successo». L'America festeggia così il suo 4 luglio, la Festa dell'Indipendenza nazionale, raggiunta 229 anni fa. Lo fa in pompa magna, come suo solito, con una missione che sinistramente evoca scenari da film di fantascienza ma che, in realtà, ha precise finalità scientifiche.
La sonda «Deep Impact» ha colpito la cometa per raccogliere informazioni utili a risalire alla formazione del sistema solare e all'origine della vita.
«Abbiamo tutti i dati che avremmo mai potuto desiderare», ha rivelato esultante Don Yeomans del Jet Propulsory Laboratory (Jpl), la sezione della Nasa che ha lavorato al progetto. «Il lavoro cominciato oggi ci accompagnerà fino alla pensione». Nulla a che vedere, quindi, con i disastri del film di Mimi Leder (Deep Impact, uscito nel 1998) da cui ci si è ispirati per dar nome alla sonda. «Tempel 1 non costituisce alcun pericolo per la Terra, né adesso, né nel futuro prevedibile», assicura Yeomans. A un anno e mezzo dalla tragedia del Columbia, la navetta con sette astronauti a bordo disintegratasi al rientro nell'atmosfera, la missione di «Deep Impact» regala un motivo di incoraggiamento e speranza alle attività della Nasa. Il momento dello scontro è stato accolto al centro di Pasadena da un tripudio di applausi e abbracci.
Sono le 22.52 a Los Angeles (le 7,52 in Italia) quando la sonda grossa come un bidone di benzina colpisce Tempel 1, dopo un viaggio di 173 giorni e un percorso lungo 431 milioni di chilometri. Una missione preparata per anni e durata 6 interminabili mesi. Tre minuti più tardi arriva la conferma. Missione compiuta. Circa 3,7 secondi prima erano giunte al centro di Pasadena le prime immagini ad alta risoluzione del corpo celeste. La grossa «patata» da 362 chili, che da sola ricoprirebbe metà dell'isola di Manhattan con il suo diametro da 6,4 chilometri, appariva segnata da dorsali, crateri, ghiacciai. Ora lo scontro assumeva connotati fantascientifici. «L'impatto è stato più violento di quello che ci aspettavamo. Non poteva andare meglio», è stato il commento di uno scienziato.
Le immagini della collisione, anche se in bianco e nero, sono state girate subito sul sito della Nasa. Le riprese della navetta madre del «proiettile» sonda Deep Impact colgono il momento dell'impatto e gli attimi successivi. Le foto, scattate da circa 500 chilometri di distanza, mostrano un bagliore bianco intenso, dalla forma irregolare e allungata, che stride sullo sfondo nero dello spazio.
Dalla cometa schizza fuori un cono rovesciato di detriti provocati dall'esplosione. Tanti curiosi e appassionati si sono riuniti in molte località statunitensi per vedere l'evento dagli osservatori astronomici. «E' come vedere un film di fantascienza», ha commentato un medico sulla spiaggia di Waikiki, nelle Hawaii.
Durante la missione non sono mancanti momenti di tensione. Per centrare il bersaglio la sonda, dotata di mezzi direzionali, ha dovuto effettuare tre successive piccole correzioni di rotta negli ultimi 90 minuti antecedenti la collisione.
L'impresa presentava enormi difficoltà: «E' come un proiettile che cerca di colpire una altro proiettile» ha provato a spiegare Rick Grammier, capo progettista della sonda. Al Diza, numero due della Nasa, esprime tutta la sua soddisfazione: «E' assolutamente straordinario riuscire a star dietro a una cometa per così tanto tempo e piazzare una sonda nel posto giusto, al momento giusto per creare la situazione ideale per le ricerche».
Infatti ora per gli scienziati arriva il momento più bello. Si inizierà ad analizzare il materiale prodotto dal «botto galattico» di Tempel 1, la cometa scoperta nel lontano 1867 e che circumnaviga l'orbita del Sole in cinque anni e mezzo (l'urto, secondo gli scienziati, non dovrebbe averne modificato di molto la traiettoria). Si valuteranno le informazioni che l'esplosione consentirà di ricavare: l'obbiettivo è capire la composizione e la struttura della cometa, formatasi miliardi di anni fa, quando il Sistema solare era ai primordi. Nella speranza di conoscere qualcosa in più del mistero dell'Universo.
CONFITEOR
05-07-2005, 19:18
NASA
http://deepimpact.jpl.nasa.gov/home/index.html
http://www.nasa.gov/mission_pages/deepimpact/main/index.html
jumpermax
05-07-2005, 19:25
:stordita: -edit-
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