[X] My Assistant

[Guest_Sunspot_*]

A nice shot of Hyperion

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=33556

[Phil Stooke]

Here is a composite view of the images taken during the August flyby of Hyperion.



It is lower resolution than the June flyby (I also posted a composite of those images), but still better than Voyager resolution. It very conveniently fills the gap in Hyperion rotation that was missing in June.

The most prominent feature is the long curving scarp, Bond-Lassell Dorsum. Since it has a mound at its center I interpret it as the remains of a crater with a diameter about 80% of the long axis of Hyperion. Some people doubt that such large craters can be formed without destroying the target, but this is, I think, based on a misunderstanding of the physics of the cratering process. The crater is excavated by an expanding hemispherical shock wave, which loses energy as (i) some is used to eject debris, and (ii) it is spread out over a larger surface. By the time it gets to full crater size it has lost much of its disruptive power (or it wouldn't be at full crater size...) Only if the shock wave is still capable of digging a crater after it has fully traversed the target does the target get blown apart completely.

Deimos and Vesta both have craters this size, relative to their mean diameters, at their south poles. (Rapid rotators would preferentially reorient to place a giant crater at a pole).

Phil