Tuesday, September 27, 2005

Cassini Approaching Tethys (And Hyperion Too!)

This orbit by the Cassini orbiter will include flybys of both Hyperion and Tethys. The Tethys flyby was added a few months ago due to increasing interest in this moon as a contributor of ring material. Here are the best Voyager views of this moon.

This view, from Voyager 1, clearly shows a dark band across the center of the disk. The existance of this has been seen in Cassini's images too, but the orgin is not yet known.

This is a color view of Tethys from Voyager 2's approach to the moon. It shows on the terminator the degraded Ithaca Chasma, a huge canyon bisecting this moon.

This is the last Voyager 2 view, showing Ithaca Chasma in the center and to the left. Within the next view days, Cassini should supercede this view. This was the best view (5 km/pixel) that either Voyager obtained before pointing errors and scan platform problems ruined imaging sequences.

With the scan platform sticking and the spacecraft off target, this is the only frame from the highest resolution mosaic of Tethys, taken at 2.2 km/pixel, to catch a corner of the moon. For years, this stood as the mysterious best view of this world. Cassini has already doubled this resolution, and at last the weekend has arrived where Tethys receives true closeup treatment! Stay tooned!

No comments: