QUOTE (djellison @ Feb 14 2007, 11:21 AM)
Problem is, it'd be fairly hard to see - and require an exposure long enough to probably smear such a shadow to a greater ammount than its own width
Hmmm...I'm not so sure. Here's my reasoning:
Previous sixty-second pancam exposures of the night sky resulted in stars of around the 7th magnitude being seen. Thinking empirically, Deimos's casting of a shadow - on a par with Venus's and at the limit of human eye perception, should be just catchable in an exposure that roughly mimicks that of the human eye. Since we have a limiting magnitude of around 6, that would suggest a Pancam exposure of around 25 seconds would be the minimum required.
Since Phobos is "up" for around five and a half hours at the MERs latitude, and Deimos even longer the angles of shadows won't change much at all over (even more shadow-catching) 1 to 2 minute exposures. Being near the equator doesn't help much in terms of getting good, long shadows when the moons are near their zenith, but this means short shadows won't move much either.
As Phobos does about 1860m/s over the ground, at an altitude of some 5830 km, the end of the shadow of a 1.4m-tall pancam mast is only going to move at just over an inch in a minute.
All that said, if I see a problem at all, it's with the nearly forty-to-one contrast ratio between the two light sources: I'm not sure the pancam could detect a washed-out Deimos shadow at that level.
Andy