I love this shot of Janus!
I fully understand the need to focus on Titan, and the results of all the flybys have been stupendous, but I must say, imaging of the small moons is very interesting to me. Also, the other large moons, Iapetus in particular, are of great interest to me. Iapetus is a mysterious object, and even with the two close flybys, remains so. The imaging of its equatorial mountain range was quite literally, stunning! I spotted multiple landslides of enormous scale on the flanks of the mountain range, but I've not seen any discussion of those amazing slump features.
There is one other really dramatic landslide in evidence on Iapetus, within one of the large craters. This large crater is approximately 375 miles across, and features a smaller, 75 mile diameter crater within it, that appears to have impacted such that it's rim is almost exactly tangent to the inner rim of the larger crater. This smaller crater is nearly half filled with an enormous landslide that propagated off the rim of the larger crater, which at this location is about 15km high! From the looks of the landslide, it appears to be perhaps 5km thick? When that landslide cut loose, it's impossible to imagine the forces involved...truly an awesome feature on Iapetus!
The best image I've seen of it is at the following address...
http://photojournal.jpl.nasa.gov/jpeg/PIA06171.jpg
Great examples of massive slumping are evident on many of the moons, including the bright splat crater on Rhea, which has large lobular flows off of it's crater walls. That one in particular brought a question to my mind, which is, where did the energy come from to soften that material enough to cause the mass slippage? The crater floor is peppered with small craters, but the landslides are free of craters, which indicates that the slumping occurred long after the formation of the crater, and at least geologically speaking, perhaps not so long ago (a billion years?)...which makes the question of where the energy came from even more interesting. I thought, other nearby impacts, but the lobular form of the slides would seem to indicate liquefaction occurred...which would seem to indicate thermal energy transfer? The related image (wide angle) that I've looked at was taken on November, 26, 2005, is as follows...W00012124...an amazing image to be sure. So...anyone have theories on how those lobular flows were formed, in such a low energy environment?
One other moon that has been woefully missed, in terms of hi-resolution imagery, is Mimas. No hi-res imagery of the crater Herschel have been captured, only medium res. It's clear from the medium res imagery that this crater has been filled with mass slumping...but the lack of hi-res imagery makes it very frustrating. And while this post might indicate otherwise, I'm NOT obsessed with landslides!
I think I've written enough for now...
Matt
Great image.
Saw this once before as a shadowy noisey raw image. It's great to see that some of the smaller moons are also being researched like Hyperion, Janus, Epimetheus, Helene, Telesto, Phoebe, etc.
Wonder if Janus is like Epimetheus, an icy rubble pile held together by gravity?
Does anyone know when the Helene encounter will be? Is there any chance of a close passes of Calypso, Telesto (again) Polydeuces, etc?
Andrew Brown.
