[meteorite-list] Cassini Flyby of Hyperion Reveals Tortured World

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Sep 28 17:03:24 2005
Message-ID: <200509282101.j8SL1uT09139_at_zagami.jpl.nasa.gov>

http://www.newscientistspace.com/article/dn8065--cassini-flyby-of-hyperion-reveals-tortured-world.html

Cassini flyby of Hyperion reveals tortured world
Stephen Battersby
New Scientist
28 September 2005

Just two days after Cassini visited Saturn's moon Tethys, it has flown
past Hyperion, one of the smaller and odder moons of the ringed planet.

Hyperion is potato-shaped: 360 kilometres long, but only about 250
kilometres across. Its rotation is chaotic, tumbling unpredictably under
the influence of Saturn's and Titan's gravity. And it is exceptionally
dark for a Saturnian moon, reflecting only 30% of the light that falls
on it, with a distinctly red tint.

The biggest question for Cassini to answer is why Hyperion is so
misshapen when other asteroids and moons of about this size are much
more spherical. One theory is that it is merely a fragment of a larger
moon that was shattered in a violent impact.

Cassini's pictures certainly show a tortured world, riven by craters and
girdled by a giant cliff face tens of kilometres high.

The new images were gathered early on Monday morning, from as close as
500 kilometres to Hyperion's surface. During the flyby, Cassini's radar
also measured slight changes in the speed of the spacecraft. This will
give an idea of the strength of Hyperion's gravity, and therefore its
mass. Mission scientists hope to discover whether the moon is solid rock
or a loosely packed "rubble pile".

The Cassini team should also be able to map the chemical make-up of
Hyperion's surface to discover whether it is dusted with dark material
drifting in from Saturn's sooty outer moon, Phoebe.
Received on Wed 28 Sep 2005 05:01:56 PM PDT