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Key to Giant Space Sponge Revealed

By Ker Than,
Posted: 2007-07-07 07:20:21
Filed Under: Science News
Space.com


(July 7) - One of the strangest moons in our solar system is Hyperion, a Saturnian satellite so pockmarked by deep craters that it looks like a giant, rotating bath sponge adrift in space. New image analyses suggest the moon's odd appearance is the result of a highly porous surface that preserves craters, allowing them to remain nearly as pristine as the day they were created.

The finding is just one of several new details about the quirky moon revealed in two studies published in the July 5 issue of the journal Nature. Scientists determined that Hyperion is composed mostly of water ice and that the bottoms of its craters are covered in a dark red gunk that could be the key to resolving some of the moon's other strange properties.

Hyperion is all kinds of weird. It is one of the largest non-spherical bodies in the solar system. The moon is oval shaped and about 250 miles at its widest point. Unlike most of Saturn's other satellites, it is not tidally locked to the ringed-planet. Earth's moon is tidally locked, which is why we always see the same face of it. Instead, Hyperion undergoes "chaotic rotation," meaning its axis of rotation shifts so much that scientists can't reliably predict its orientation in space.

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Perhaps the most striking thing about Hyperion, however, is its extremely pitted appearance. Hundreds of craters cover the surface, with most averaging 1 to 6 miles wide.

The latest analyses of data obtained by NASA's Cassini spacecraft during its flybys of Hyperion in 2005 and 2006 show that about 40 percent of the moon is empty space.

Hyperion's high porosity could explain its sponge-like appearance, scientists say. A large meteor striking Earth's moon will gouge a deep hole on the surface and send up a giant spray of rock and dust. The excavated material rains back down onto the lunar surface and into other craters, partially filling them in. In contrast, the surface of Hyperion is so brittle that an object striking it will create a hole but not send any material flying. Surrounding craters remain as deep as when they first formed.

"Theoretical work suggests that if you have a porous target, craters may be more compressional instead of being explosive and tossing stuff out," said Peter Thomas of Cornell University, who led one of the studies.

The new analyses also confirmed that Hyperion is composed mostly of water ice with very little rock. "We find that water ice is the main constituent of the surface, but it's dirty water ice," said Dale Cruickshank, a researcher at NASA Ames Research Center who led the second study. "Fresh water ice would look very bright in reflected sunlight, but this is definitely dingy."

Story Telling Kit

Which mystery is most intriguing?

  • Sponge moon
  • Giant red spot
  • Water on Mars
  • Pluto's status
Cruickshank's team attributes the moon's dinginess to contamination by a dark, organic material that litters Hyperion's surface and is concentrated in several of its craters.

The reddish gunk contains long chains of carbon and hydrogen and appears very similar to material found on other Saturnian satellites, most notably Iaeptus.

The third-largest moon of Saturn, Iaeptus is an unusual two-toned world with one half covered in gleaming ice and the other half coated in the same mysterious dark material that covers Hyperion.

This link has some scientists speculating that Hyperion's strange shape and Iaeptus' odd paint job share a common origin. "Maybe Hyperion got hit and is the origin of this dark stuff which then got spewed out and got swept up by Iapetus," Cruickshank told SPACE.com.

According to this idea, a giant object collided with a still-round Hyperion in the distant past. The impact sent Hyperion into a cosmic spin that it is still reeling from today and caused a shower of dust-like particles to fly outwards through space, where it struck an unaware Iapetus full in the face.

"That's not completely implausible," Cruickshank said. If Iapetus "ran into a dust storm as it orbited around Saturn, the dust would be distributed the way we see it."

As to what the object might have been that struck Hyperion, Cruickshank notes that the same reddish gunk can also be found on other icy objects in the outer solar system, including other moons, Kuiper belt objects and comets.

(c) 1999-2007 Imaginova Corp. ALL RIGHTS RESERVED.

2007-07-05 12:37:09
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tothestarz 04:25:23 PM Jul 08 2007

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The more we learn about the universe, the more cool it gets. There are so many mysteries and revelations to discover! With each new insight the cosmos is less an empty, barren wasteland, and more like a vast, inviting playground. How much more will we learn by venturing beyond this small planet? How much more will we learn about ourselves? Perhaps, even the very mind of God? Maybe if we learn to dwell in the infinite we might experience the shift in perspective we seem to need right now. This is the future of humankind, it is our purpose and our destiny. The stars await.

TuPop Cannoli 04:07:16 AM Jul 08 2007

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LIFE IS A GAME FOR THOSE WHO HAVE IT ALL. TO THE REST OF US, WE JUST WORK AND SPEND OUR WAGES TO KEEP UP WITH THE NEXT GUY WHO'S ALSO SPINNING HIS WHEELS. THE'RE OUT THERE WATCHING ALL THIS BS. WHEN WE KILL EACH OTHER, LIKE IN THE "TWILITEZONE", THE'RE GOING TO SHAKE THE LITTLE GREEN HEADS AND FLY AWAY. IF ALL THE PEOPLE IN THE MIDDLE EAST HAD THE SAME FREEDOMS GOING BACK NOT TO MANY YEARS AGO. WE MIGHT NOT HAVE SEEN SETEMBER 11TH. THE WORLD JUST MIGHT HAVE BEEN A BETTER PLACE. AND JUST MAYBE, THOSE WHO HAVE SO MUCH, WOULD HAVE MORE TO GIVE. YANO, SOME TIMES I THINK LIFE IS JUST BOWL OF CHERRY PITS! ALL WE CAN DO IS "ROCK ON" THE UNIVERSE IS THE MASTER AND ALWAYS WILL BE. WHAT IS MORE POWERFUL THE UNIVERSE IN MOTION? GOD IS THE UNIVERSE. WE JUST CAN'T SEE THAT. SO THE OLD MEN WROTE ALOT OF WORDS THAT REALLY MEAN SOMETHING. IS IT ALL TRUE? THINKABOUTIT.

mismisue 06:46:03 PM Jul 07 2007

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:D

hylandgrl1 03:31:05 PM Jul 07 2007

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I think for to look good you must have money spend. If not, then good to not for looking. American schools only for good to teach English, not for nothing unusual. Future of America only rely on must learn for future. Other culture will much teach America if only wake up.

Diggindanfl91 02:06:41 PM Jul 07 2007

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That guys right, NASA is wastin american dollars. least they could do is design a new shuttle that wont blow up. i mean come on, it was designed in '71, we have new fricken technology, why don't they use it? I personally think they should give space programs to individual companies so that they're not wasting our cash.

rerome6 01:58:08 PM Jul 07 2007

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Well Chicago God wants u to use ur mind but u refuse it, What God can do about it.

archerair 01:53:23 PM Jul 07 2007

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I have no comments for something I have no control.

katseye116 01:47:35 PM Jul 07 2007

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none of you people make any damn sense at all.

jimaddiehaines 01:25:32 PM Jul 07 2007

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These "thoughts" would be interesting if brendance didn't have a comment every 10 seconds. Go worship your fake idol and leave the rest of us in peace

sobiaaziz 01:22:44 PM Jul 07 2007

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Shotcreteman1 what a comment u took the words right out of my mouth its about time someones tell's them up GOOD JOB!

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