For the first time, NASA's Cassini spacecraft revealed surface details of Saturn's moon Hyperion. During a flyby in September 2005, it saw cup-like craters filled with hydrocarbons. These substances may indicate a more widespread presence of basic chemicals necessary for life in our solar system.

Water and carbon dioxide ices were found, as well as dark material that fits the spectral profile of hydrocarbons.

Cassini's ultraviolet imaging spectrograph and visual and infrared mapping spectrometer captured compositional variations in Hyperion's surface. These instruments, which map mineral and chemical features of the moon, returned data confirming the presence of frozen water found by earlier ground-based observations, but also discovered solid carbon dioxide (dry ice) mixed in unexpected ways with the ordinary ice. Images of the brightest regions of Hyperion's surface show frozen water that is crystalline in form, like that found on Earth.

In this map, blue shows the maximum exposure of frozen water, red denotes carbon dioxide ice ("dry ice"), magenta indicates regions of water plus carbon dioxide, yellow is a mix of carbon dioxide and an unidentified material.

The July 5 issue of Nature reports details of Hyperion's surface craters and composition observed during this flyby, including keys to understanding the moon's origin and evolution over 4.5 billion years. This is the first time scientists were able to map the surface material on Hyperion.

Hyperion, Saturn's eighth largest moon, has a chaotic spin and orbits Saturn every 21 days.

• Key to Giant Space Sponge Revealed
• New Pictures of Saturn's Battered Moons
• Saturn Data Sheet

--NASA and SPACE.com Staff

Credit: NASA/JPL/University of Arizona/Ames