Pictures: New Views of Saturn's "Sponge" Moon Hyperion

Spongy Tumbler

Image courtesy Caltech/SSI/NASA

Cassini snapped this close-up of Hyperion's limb during the spacecraft's August 25 flyby. The sponge-like moon has been known to scientists since 1848 and was named after one of the Titans of Greek mythology.

However, Hyperion is one of Saturn's most distant moons and is relatively small, at about 168 miles (270 kilometers) wide. What's more, the moon's potatolike shape causes Hyperion to "tumble" along on its irregular orbit-the only known moon to have such a chaotic rotation.

The moon's wild movements make it nearly impossible for scientists to predict which areas will be visible at any given time, making it hard to target specific areas for imaging. The newly released pictures from Cassini's flyby therefore revealed some regions of Hyperion for the first time.

(Related: "Saturn's 'Walnut' Moon Mystery Cracked?")

Published August 31, 2011

Saturn Moon's Dark Depths

Image courtesy Caltech/SSI/NASA

Dark material inside many of Hyperion's craters—as seen in a close-up from the August 25 flyby—is among the moon's intriguing mysteries. Previously gathered data suggest the material may be organic.

"There has been some pretty good evidence that this material may be rich in complex hydrocarbons, which we sometimes call the building blocks of life," NASA's Buratti said. The organic materials may have come from another Saturn moon, Iapetus.

(See "Saturn 'Sponge Moon' Has Ingredients for Life?")

Published August 31, 2011

Cold Colors

Image courtesy U. Arizona/SSI/NASA

Cassini had previously visited Hyperion in September 2005, and the spacecraft's visual and infrared mapping spectrometer was used to create this colorized map of the substances found on the moon's frigid surface, where temperatures are around -300 degrees F (-180 degrees C).

"We found carbon dioxide on Hyperion," Buratti explained. "The surface is largely water ice, and the craters on the bottom are kind of dominated by that dark material, which we think is rich in complex hydrocarbons."

Cassini's more recent flybyprovided reams of similar data for future analysis of new parts of the moon. (Related: "New Saturn Moon-Tiny Gem Found in Outer Ring.")

Published August 31, 2011

Battered and Bruised

Image courtesy SSI/NASA

In 2005 Cassini buzzed Hyperion's surface at an altitude of just 310 miles (500 kilometers) and snapped high-resolution pictures that showcase the moon's unusual surface.

For instance, this mosaic of five images includes a 650-foot-wide (200-meter-wide) impact crater (right of center) that's filled with dark material and surrounded by numerous bright-rimmed craters.

"It's the only known satellite or moon that's this big and not spherical—it's so battered that it has altered its shape," NASA's Buratti said.

(Also see "Saturn Moon Has Oxygen Atmosphere.")

Published August 31, 2011

Hyperion Compressed?

Image courtesy SSI/NASA

A false-color picture shows crisp detail across Hyperion in a picture based on data from Cassini's 2005 flyby. The colors represent differences in surface composition.

Hyperion is extremely porous and has low gravity on its surface. These traits could mean that collisions with space rocks repeatedly compressed the moon's surface material into the funky shape we see today, while any ejecta simply drifted off into space.

Hyperion itself may be a remnant of an ancient, larger moon that was shattered by a cosmic collision. (Also see "Saturn's Rings Made by Giant 'Lost' Moon, Study Hints.")

Published August 31, 2011