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29.05.2015
This false-color view of Hyperion was obtained during Cassini's closest flyby of Saturn's odd, tumbling moon on Sept. 26, 2005. Image credit: NASA/JPL-Caltech/SSI
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NASA's Cassini spacecraft will make its final close approach to Saturn's large, irregularly shaped moon Hyperion on Sunday, May 31.
The Saturn-orbiting spacecraft will pass Hyperion at a distance of about 21,000 miles (34,000 kilometers) at approximately 6:36 a.m. PDT (9:36 a.m. EDT). Mission controllers expect images from the encounter to arrive on Earth within 24 to 48 hours.
Mission scientists have hopes of seeing different terrain on Hyperion than the mission has previously explored in detail during the encounter, but this is not guaranteed. Hyperion (168 miles, 270 kilometers across) rotates chaotically, essentially tumbling unpredictably through space as it orbits Saturn. Because of this, it's challenging to target a specific region of the moon's surface, and most of Cassini's previous close approaches have encountered more or less the same familiar side of the craggy moon.
Cassini scientists attribute Hyperion's unusual, sponge-like appearance to the fact that it has an unusually low density for such a large object -- about half that of water. Its low density makes Hyperion quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.
Cassini's closest-ever Hyperion flyby took place on September 26, 2005, at a distance of 314 miles (505 kilometers).
Cassini's next notable flyby after May 31 is slated for June 16, when the spacecraft will pass 321 miles (516 kilometers) above icy Dione. That flyby will represent the mission's penultimate close approach to that moon. In October, Cassini will make two close flybys of the active moon Enceladus, with its jets of icy spray, coming as close as 30 miles (48 kilometers) in the final pass. In late 2015, the spacecraft will again depart Saturn's equatorial plane -- where moon flybys occur most frequently -- to begin a year-long setup of the mission's daring final year. For its grand finale, Cassini will repeatedly dive through the space between Saturn and its rings.
Quelle: NASA
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Update: 3.06.2015
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Cassini Sends Final Close Views of Odd Moon Hyperion
NASA's Cassini imaging scientists processed this view of Saturn's moon Hyperion, taken during a close flyby on May 31, 2015.
Credits: NASA/JPL-Caltech/Space Science Institute
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This raw, unprocessed image of Hyperion was taken on May 31, 2015 and received on Earth June 1, 2015. The camera was pointing toward Hyperion at approximately kilometers away, and the image was taken using the IR2 and IR1 filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2016.
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This raw, unprocessed image of Hyperion was taken on May 31, 2015 and received on Earth June 1, 2015. The camera was pointing toward Hyperion at approximately kilometers away, and the image was taken using the BL1 and CL2 filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2016.
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This raw, unprocessed image of Hyperion was taken on May 31, 2015 and received on Earth June 1, 2015. The camera was pointing toward Hyperion at approximately kilometers away, and the image was taken using the CL1 and IR1 filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2016.
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This raw, unprocessed image of Hyperion was taken on May 31, 2015 and received on Earth June 1, 2015. The camera was pointing toward Hyperion at approximately kilometers away, and the image was taken using the CL1 and GRN filters. The image has not been validated or calibrated. A validated/calibrated image will be archived with the Planetary Data System in 2016.
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NASA's Cassini spacecraft has returned images from its final close approach to Saturn's oddball moon Hyperion, upholding the moon's reputation as one of the most bizarre objects in the solar system. The views show Hyperion's deeply impact-scarred surface, with many craters displaying dark material on their floors.
During this flyby, Cassini passed Hyperion at a distance of about 21,000 miles (34,000 kilometers) at closest approach. Cassini's closest-ever Hyperion flyby took place on Sept. 26, 2005, at a distance of 314 miles (505 kilometers).
Hyperion is the largest of Saturn’s irregular, or potato-shaped, moons and may be the remnant of a violent collision that shattered a larger object into pieces. Cassini scientists attribute Hyperion's peculiar, sponge-like appearance to the fact that it has an unusually low density for such a large object -- about half that of water. Its low density indicates Hyperion is quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.
Cassini will make several more close flybys of Saturn's moons this year before departing the planet's equatorial plane to begin a year-long setup of the mission's daring final act. For its grand finale, set for 2017, Cassini will repeatedly dive through the space between Saturn and its rings.
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado. The California Institute of Technology in Pasadena manages JPL for NASA.
Quelle: NASA
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