Greetings from Puerto Rico!

I've finished my presentation of these new data (Schenk, Bull. AAS, vol. 41, p. 992, 2009), and so can now post our new color maps of the 5 inner large icy satellites of Saturn: namely Mimas, Enceladus, Tethys, Dione and Rhea. There is a lot of interesting information in these data, which our team (currently at 5 members) is working on and will publish on later this year! Here is a short summary. Moe details can be found at http://stereomoons.blogspot.com. I show the full color maps here.

The most interesting features in these new maps are the UV-bright equatorial band on Mimas and the anomalous equatorial feature on Rhea. The Mimas band is in fact very similar to the dark band across the front face of Tethys and probably formed by the same mechanism. We think we have an explanation for this involving high energy electrons and are working on the details. The Rhea feature is very narrow, only a few km across and very close to the equator (part of this feature has in fact been described previously in another umsf post in a ring section, but ours is an independent discovery of the same feature, our color map is global and we show here that it IS unique to Rhea). The image below is a section of the Rhea map zooming in very close the equator across the entire leading hemisphere. We therefore support the idea that these features (which oddly resemble machine-gun fire across Rhea) formed by the impact of infalling debris from a circum-Rhea ring. There is lots more that I havent talked about (the global asymmetries, the tectonic patterns on Rhea and Dione, etc.) which i will go into more detail int he future, but its clear from the maps that the icy satellites of Saturn are anything but bland.

paul

NEW DETAILS:
The global maps shown here are three-color maps using IR, Green and UV. They are essentially enhanced natural color.
The narrow Rhea map is a part of the IR/UV ratio map of Rhea which i will post hopefully tomorrow. It shows the equatorial region of the leading hemisphere only.

VERY interesting with the Rhea equatorial 'stripe' (as noticed here some months back by UMSF'er Gordon U.) There has obviously been a quite energetic 'dark-material' event in the saturn system at some stage - we have darker 'stuff' in the craters of Janus, Hyperion and Epimetheus, the aforementioned Rhea band (and possibly rings), that on Tethys and Mimas and half of Iapetus coated with gunk.
A past impact of a Kuiper belt object perhaps ??

It's worth noting the Rhea image is actually an ir/uv ratio mosaic which shows the pattern is blue. The spots are not dark at all and barely noticeable if at all in single band images. They have almost no albedo contrast. my apologies to gordon and thanks for his postings. I do not usually read the ring related posts and completely missed it. I discovered that thread some time after we made our own discovery of the Rhea features, which lead to the subsequent full global maps of each satellite. It was motivated by my stereo work in the same area, which i will post later . . .
cheers
Paul

Any thoughts on that other geometrically perfect icy moon equatorial feature, the Iapetus ridge? Does the Rhea discovery tip the balance of plausibility there?

If you look at Dione and Rhea, they look very much alike in those images! Except Rhea seems more battered and Dione is more smooth.