* Astronomy

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RE: The Cassini spacecraft

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After so many close flybys of Enceladus, were starting to feel as if this little moon of Saturn is an old friend. But during the encounter planned for Nov. 2, 2009, we are going to get up-close and personal. Cassini is going to take its deepest dive yet into the plumes spewing out from the moons south pole to try to learn more about their composition and density.
The spacecraft is going to approach within about 100 kilometres of the surface. Weve been closer before (25 kilometres), but weve never plunged quite so deeply into the heart of the plume.
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Cassini Data Help Redraw Shape of Solar System
Images from the Ion and Neutral Camera on NASA's Cassini spacecraft suggest that the heliosphere, the region of the sun's influence, may not have the comet-like shape predicted by existing models. In a paper published Oct. 15 in Science Express, researchers from the Johns Hopkins Applied Physics Laboratory present a new view of the heliosphere, and the forces that shape it.

"These images have revolutionised what we thought we knew for the past 50 years; the sun travels through the galaxy not like a comet but more like a big, round bubble. It's amazing how a single new observation can change an entire concept that most scientists had taken as true for nearly fifty years" - Stamatios Krimigis of the Applied Physics Lab, in Laurel, Md., principal investigator for Cassini's Magnetospheric Imaging Instrument which carries the Ion and Neutral Camera.

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Cassini Reveals New Ring Quirks, Shadows During Saturn Equinox
NASA scientists are marvelling over the extent of ruffles and dust clouds revealed in the rings of Saturn during the planet's equinox last month. Scientists once thought the rings were almost completely flat, but new images reveal the heights of some newly discovered bumps in the rings are as high as the Rocky Mountains. NASA released the images Monday.

"It's like putting on 3-D glasses and seeing the third dimension for the first time. This is among the most important events Cassini has shown us" - Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

On Aug. 11, sunlight hit Saturn's rings exactly edge-on, performing a celestial magic trick that made them all but disappear. The spectacle occurs twice during each orbit Saturn makes around the sun, which takes approximately 10,759 Earth days, or about 29.7 Earth years. Earth experiences a similar equinox phenomenon twice a year; the autumnal equinox will occur Sept. 22, when the sun will shine directly over Earth's equator.

Source: NASA

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Saturn and the orbiting Cassini spacecraft are currently on the opposite side of the Sun, from the Earth.

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Credit: SOHO

This Solar & Heliospheric Observatory (SOHO) image was taken on the 18th September, 2009, and shows Saturn before it passed behind the Sun.
Saturn is currently at Superior Conjunction.

Source: Jet Propulsion Laboratory

Blobrana · L

Cassini spacecraft

Blobrana · L

RE: The Cassini spacecraft

Blobrana · L

Saturn, with its majestic rings and mysterious icy moons, has long captured the imagination.
This week, images from the Cassini spacecraft revealing the secrets of the ringed planet went on display at the Royal Observatory in Greenwich, London. Cassini, a joint mission of Nasa, the European Space Agency and the Italian Space Agency, sent back the images between 2004 and 2008.

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The Cassini spacecraft flew by Titan at an altitude of 4,146 kilometres. During this flyby, the Radio Science Subsystem (RSS) observed atmospheric and ionospheric occultations. This was the first near-equatorial radio occultation in the mission. The Ultraviolet Imaging Spectrograph (UVIS) watched Titan occult the star Alpha Eri. Earlier, RADAR got good northern polar coverage, which will help fill in a gap in the brightness temperature map

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Early this morning the Cassini spacecraft relayed information that it had successfully swapped to a backup set of propulsion thrusters late Wednesday.
The swap was performed because of degradation in the performance of the primary thrusters, which had been in use since Cassini's launch in 1997. This is only the second time in Cassini's 11 years of flight that the engineering teams have gone to a backup system.
The thrusters are used for making small corrections to the spacecraft's course, for some attitude control functions, and for making angular momentum adjustments in the reaction wheels, which also are used for attitude control. The redundant set is an identical set of eight thrusters. Almost all Cassini engineering subsystems have redundant backup capability.
Cassini has successfully completed its original four-year planned tour of Saturn and is now in extended mission operations.

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