[Space] NASA-ESA - Cassini-Hyugens

[GioFX]

Originariamente inviato da riaw
intendevo questa

c'erano amici che sostenevano che atterra sui 180-200 orari, ma secondo me era un po impossibile
avevo scommesso sui 400, non ci sono andato lontanissimo

infatti, andrebbe in stallo a quella velocità, considerando la scarsa apertura alare...

[GioFX]

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.


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.

[gpc]

Gio, ti sei svegliato adesso?
Quando vedo tra le email di notifica una fila di thread che iniziano con [Space] so che ti sei collegato...

[GioFX]

Originariamente inviato da gpc
Gio, ti sei svegliato adesso?
Quando vedo tra le email di notifica una fila di thread che iniziano con [Space] so che ti sei collegato...

no beh, un pò di tempo fa... e che ho anche altro da fare...

[GioFX]

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.


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]

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.

[gpc]

Il sito della missione, invece, è http://saturn.jpl.nasa.gov nel caso non fosse stato linkato prima...

[GioFX]

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

[GioFX]

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.

[david-1]

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.

Sei sicuro che no sia stato progettato da Nabrez?

[GioFX]

Originariamente inviato da david-1
Sei sicuro che no sia stato progettato da Nabrez?

no, Nabrez l'avrebbe fatto a legna...

[gpc]

Originariamente inviato da GioFX
no, Nabrez l'avrebbe fatto a legna...

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...

[GioFX]

Originariamente inviato da gpc


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.

[GioFX]

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.


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]

Primo incontro venerdì con Phoebe... guardate quanto è carina... (non fate caso ai brufoli )

http://saturn.jpl.nasa.gov/cgibin/gs...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]

[GioFX]

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.


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


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


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

[Thell]

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?

[GioFX]

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.

[Thell]

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?

[GioFX]

Originariamente inviato da Thell
ma da sott'acqua.......ehm...da sottometano come trasmette?

non è detto che affondi subito...

e cmq in bassa frequenza riesci a trasmettere anche in un mare di cacca...