QUOTE (ugordan @ Jul 20 2011, 09:56 AM)
I don't think that's Rhea there, it's too bright and the terrain looks like Tethys so I'm gonna go with... Tethys?
The CICLOPS "Looking ahead" page mentions a Dione-Rhea mutual event, so it should be Rhea:
"On July 18, ISS will image Dione as it passes in front of the southern half of Rhea. Dione will be 2.19 million kilometers away, while behind it Rhea will be 3.09 million kilometers from Cassini. During this transit, portions of Rhea's northern hemisphere will be obscured by Saturn's main rings."