[X] My Assistant

[ugordan]

Are there any plans for imaging Rhea on March 21? I noticed all other moons are on the wrong side of Saturn during periapsis passage except Rhea for which there's a pretty close pass, under 100 000 km, although closest approach happens at a very high phase angle.

Rhea approach geometry and closest approach from the Solar System Simulator.

[edstrick]

The Viking Orbiter cameras were designed with a fast readout cycle such that one camera was exposing and reading out while it's twin was erasing and resetting for the next exposure. I think the frame interval was 1.2 seconds between cameras so one camera cycled at 2.4 seconds total. This was necessary for strip-mosaicing of landing site candidates from a 1,500 km periapsis with a 50 meter/pixel resolution.

The drawback of the viking design was the data couldn't be recorded that fast in digital form on one tape track. The data was split into seven parallel data tracks, one pixel per track, then read out in track-sequential manner... which led to a lot of images missing one or many pixel-columns in a repetitive cycle. But they could take and record data in one hell of a hurry.

I don't know what led to the limitations in the Cassini camera frame rate, but it's almost apallingly slow.

[dilo]

High dinamic range image of Rhea+outer rings, color-coded combination of a long and a short esposure: