Is it just me or is it difficult to overcome the optical illusion in the closeup Dione photos that the craters look instead like mounds. I've turned my head sideways this way or that and I am unable to view these photos correctly. Perhaps if I download them and turn them completely upside down. Or maybe they really are undiscovered mounds - Ha!
I've been looking at enlargements of Hyperion images and finally realize what it is that makes it look so different to me from other moons. It reminds me of what a close-up of a lump of slightly eroded coral looks like: the larger crater being the polyp cores. The other imagery is that of worm pumice stone: the larger craters like the surface bubbles. What all three might have in common is a lightness and porosity.
The other oddity is that craters are of three distinct sizes: the obvious large craters; craters about a tenth the size and then very very small craters. And between all of these craters is a very soft surface void of any large craters like it was dusted over with snow. This would imply to me that Hyperion either has been subject to different conditions in space (was it a comet?)or its own unique geology, as Enceladus has its own unique geology.
Regarding PIA12809, the new closeup of Rhea's main fractures, I detect some 'smudging' in the central fracture line showing the bright cliffs which to me look like what vapor jets would look like from a fissure as we have seen on Enceladus. Likely it is just a smudge in the image, but it did catch my attention as I panned down an enlarged view of this image. Comments?