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Frosted honeycomb of a moon

Cassini images reveal ice on Saturn satellite Hyperion

Hyperion may look like a wet sponge, but the Saturnian moon is actually covered in ice. New studies of images taken by NASA’s Cassini spacecraft in September 2005 reveal that the moon — a weirdly rotating, reddish, potato-shaped satellite with a honeycomblike surface — is covered in water and carbon dioxide ices, with hydrocarbons and iron-containing compounds mixed in. In some ways, Hyperion is similar to certain comets, which suggests the moon formed elsewhere before being snared by the ringed planet, scientists report in an upcoming issue of Icarus. Further analyses, conducted by a separate team of researchers and published in the same journal, describe Hyperion’s perplexing, spongelike surface as the product of several moonscaping processes: Impacts blasting debris into space, eroding crater walls, mass wasting and sublimation have all sculpted one of the solar system’s weirdest-looking objects, the team proposes.

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