Monday, March 15, 2010

NASA Cassini Cruises By Rhea And Helene

Cassini's closest-ever flyby of Saturn's moon Rhea went quite smoothly and teams are busy checking out their data! These flybys never fail to amaze me. And the raw images - which give us an unprocessed first look - are really cool!

Raw image N00152150 gives us a view of part of the bright, fractured terrain we refer to as "wispy terrain" from about 14,000 kilometers (8,900 miles) away.
We know that Rhea's albedo overall is quite high. (When I say "albedo," I basically mean "brightness" or "reflectivity." Studying the albedo can tell a lot about surface composition, geologic processes, and interactions with external environment.)

But this image demonstrates how bright these cracks are since they are so shiny that the surrounding terrain looks quite dark. There are also some interesting apparent albedo variations seen in this image, which are really intriguing.

This raw image (N00152175) from Cassini's narrow-angle camera image was taken about 40 minutes after closest approach. The image shows a region adjacent to the wispy terrain -craters, craters everywhere! And those crater rims bright compared to the surrounding terrain.

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