[meteorite-list] Cassini Prepares for Last Up-close Look at Hyperion

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 28 May 2015 17:08:13 -0700 (PDT)
Message-ID: <201505290008.t4T08Dgc022829_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4606

Cassini Prepares for Last Up-close Look at Hyperion
Jet Propulsion Laboratory
May 28, 2015

[Image]
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

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.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European
Space Agency) and the Italian Space Agency. JPL, a division of the California
Institute of Technology, manages the mission for NASA's Science Mission
Directorate in Washington.

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov


Media Contact

Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches at jpl.nasa.gov

2015-186
Received on Thu 28 May 2015 08:08:13 PM PDT