Cassini closes in on Saturn's tumbling moon Hyperion

This flyby will help scientists improve color measurements of the moon, which will provide additional information about different materials on the satellite’s deeply pitted surface.

By Jet Propulsion Laboratory, Pasadena, California — Published: August 29, 2011

NASA's Cassini spacecraft obtained this unprocessed image of Saturn's moon Hyperion August 25, 2011. Credit: NASA/JPL-Caltech/Space Science Institute

NASA’s Cassini spacecraft captured new views of Saturn’s oddly shaped moon Hyperion during its encounter with this cratered body on Thursday, August 25. Raw images were acquired as the spacecraft flew past the moon at a distance of about 15,500 miles (25,000 kilometers), making this the second-closest encounter.

Hyperion is a small moon — just 168 miles (270 kilometers) across. It has an irregular shape and surface appearance, and it rotates chaotically as it tumbles along in orbit. This odd rotation prevented scientists from predicting exactly what terrain the spacecraft's cameras would image during this flyby.

However, this flyby’s closeness has likely allowed Cassini’s cameras to map new territory. At the very least, it will help scientists improve color measurements of the moon. It will also help them determine how the moon's brightness changes as lighting and viewing conditions change, which can provide insight into the texture of the surface. The color measurements provide additional information about different materials on the moon’s deeply pitted surface.

The latest raw images of Hyperion are online at http://saturn.jpl.nasa.gov/photos/raw/.

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ASHIRA BROOKE from FLORIDA said:

@Alan: I wanted to know more about that too so I looked it up and found this: "Hyperion orbits at a mean distance of 1,481,100 km (920,300 miles) from Saturn in an eccentric orbit. This contributes to variations in the spin or rotation of Hyperion. A stronger effect on Hyperion's rotation is that it is in resonance with Saturn's largest moon, Titan, which orbits at 1,221,850 km (759,200 miles). Thus, the two objects speed up and slow down as they pass each other in a complex set of variations. Because Hyperion is much smaller than Titan, its rotation and orbit are affected vastly more than the larger moon, and Titan apparently keeps the Hyperion orbit eccentric rather than growing more circular over time.

The great distance from Saturn and resonance with Titan has also kept Hyperion from becoming tidally locked facing Saturn. Hyperion rotates roughly every 13 days during its 21-day orbit."

It's from a NASA site: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Hyperion

Submitted: 9/14/2011 9:19:24 PM (CST)

ALAN L FALK from NORTH CAROLINA said:

"and it rotates chaotically as it tumbles along in orbit. This odd rotation..."

Huh? What does that mean? Two axes of rotation? How can that happen?

Thanks!

Submitted: 9/10/2011 11:27:37 PM (CST)

	Sun	Sun	Moon
RISE	—		—	PHASE	—
SET	—		—	DISK	—

Cassini closes in on Saturn's tumbling moon Hyperion

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