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Fraser
2004-Jul-26, 04:09 PM
SUMMARY: Cassini returned this image of Saturn's moon Mimas, which looks surprisingly similar to the Death Star from Star Wars. Mimas is 398 km (247 miles) across, and that's not a superlaser you see, but a giant crater called Herschel, which is a third the size of the moon itself. Cassini took this image on July 3, 2004, when the spacecraft was 1.7 million km (1 millions miles) away. Cassini will get a better view on August 2, 2005, when the spacecraft makes a distant flyby of heavily cratered moon.

What do you think about this story? Post your comments below.

Zac
2004-Jul-26, 06:04 PM
nice image from Cassini B)

Doc cjm
2004-Jul-26, 06:55 PM
How can Mimas get hit with as such a big object to creat that crater and still not fracture that moon in a thousand pieces?

Doc CJM

The Meal
2004-Jul-26, 07:18 PM
http://images.google.com/images?q=tbn:0uv4...s_kits/8193.jpg (http://images.google.com/images?q=tbn:0uv4A_z_MZIJ:darkstar-sifi.co.uk/images/stawars_kits/8193.jpg)

Freaky!

~The Meal

Planetwatcher
2004-Jul-26, 07:52 PM
Cool pic. It does look just like the death star.

Epigon
2004-Jul-26, 09:10 PM
Originally posted by Doc cjm@Jul 26 2004, 06:55 PM
How can Mimas get hit with as such a big object to creat that crater and still not fracture that moon in a thousand pieces?

Doc CJM
perhaps it was a small object but with high impact speed. then the inertia of Mimas' matter was probably too high to allow the energy of the impact to travel through the whole moon

antoniseb
2004-Jul-26, 09:26 PM
Originally posted by Doc cjm@Jul 26 2004, 06:55 PM
How can Mimas get hit with as such a big object to creat that crater and still not fracture that moon in a thousand pieces?
There's lots of ways.

1. perhaps it's not an impact crater, but a volcanic caldera [unlikely].
2. perhaps it had a slow collision when the moon was a slushy ice-ball.
3. perhaps it did shatter into a thousand pieces, and this is how it reassembled, and Saturn's E-ring is the rest of the debris.

Here's a Voyager shot of the same moon:


http://www.planetary.org/saturn/images/mimas_v1_801112_dist0425k_528x499.jpg

JESMKS
2004-Jul-27, 04:21 PM
If it had been a slow impact, there probably would not be the energy to create the explosion necessary to create a circular crater unless the impact was vertical to the surface of Minas. The other craters on Minas appear to be circular. Its hard for me to believe that all the impacts on a small moon would have the ability to create circular craters. I'll vote for the caldera theory created by out gassing.
Jack

Duane
2004-Jul-27, 10:56 PM
Jack, how would your idea account for the central peak within the crater? Furthermore, the crater is some 80 miles wide, yet only about 6 miles deep. Where would the material being outgassed come from?

Personally, I think it was a high-speed impact that melted the floor of the crater and very nearly broke the moon apart. It seems to me that images from Voyager of the back-side of Mimas shows a "jumbled" terrain on the opposite side of Herschel crater, suggesting the impact caused significant fracturing.

As the moon is thought to be mostly ice with a rocky core, the impact would not have created a deep hole like you would expect on a rocky planet.

JESMKS
2004-Jul-28, 12:35 AM
Crater lake in Oregon has two central peaks in it's caldera and Newberry Crater, also in Oregon has a central peak. If the blister that formed the caldera came from a steam explosion produced by the low pressure and low temperature acting on ice within the moon , the steam producing the explosion would be lost into space and the remaining rock materials would fall back forming the caldera. A last puff of steam could produce the secondary cone.
Jack

Jerimiah
2004-Aug-17, 12:55 AM
[B]I truely believe it is an impact crater, with the fractures from the other side of the moon evident, it clearly shows that the moon was nearly broken into pieces from the impact. Volcanic, doubtful.

Jerimiah

Jerimiah
2004-Aug-17, 12:57 AM
Originally posted by JESMKS@Jul 28 2004, 12:35 AM
Crater lake in Oregon has two central peaks in it's caldera and Newberry Crater, also in Oregon has a central peak. If the blister that formed the caldera came from a steam explosion produced by the low pressure and low temperature acting on ice within the moon , the steam producing the explosion would be lost into space and the remaining rock materials would fall back forming the caldera. A last puff of steam could produce the secondary cone.
Jack
I agree, there are many craters throughout the world with caldera cones in the center after an eruption.

Jerimiah