QUOTE (nprev @ Dec 2 2010, 05:48 PM)
Has Cassini done any extended nightside obs of Saturn's equatorial region? Reason I ask is that I would expect that at least some small fraction of the ring material eventually impacts the planet, and therefore there might be observable meteors. Constraining that infall rate would seem to be a significant data point for understanding the rings evolution & longevity. Might even help to derive a size distribution for the larger (<10cm?) ring particles.
I don't know if this is even possible to do given the enormous amount of backlighting in the Saturn system from the rings, and you'd probably have to do it when Cassini wasn't in an equatorial orbit. Still, I'm curious.
I'd have to check the latitude, but it's possible. There have been night side images taken to look for lightning. My guess is that any influx of ring particles could not be seen. There is (or should be) D ring particles entering the atmosphere, but those are primarily < 0.1 mm (see Hedman et al., 2007.) They definitely wouldn't produce enough of a flash to be seen. In addition, lightning has been observed, but only at equinox (where the ring shine went to zero) and I think those were estimated to be very large events by terrestrial standards. If you take that as a standard for just-detectable flashes, I doubt Cassini could see a meteor.
(By the way, in the earlier post, I did drop a zero. It should be a 470 m^2/kg, not 4700, sail to hover a kilometer over the rings.)