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Unmanned Spaceflight.com _ Saturn _ Exploring the Rings

Posted by: Bill Harris Jul 29 2010, 01:33 PM

This might be a way for an orbiter to move closer to the ring plane without crossing the ring plane:

http://www.sciencedaily.com/releases/2010/07/100726094749.htm

"The late Dr Forward -- a renowned physicist who worked in the United States and from his second home in Scotland -- believed it was possible to use 'displaced orbits' to deploy more satellites to the north or south of the Earth's equator, helping to meet the growing demand for communications."

--Bill

Posted by: Frank Crary Jul 29 2010, 04:31 PM

Interesting idea. I don't think I've heard Forward's solar sail idea applied to hovering over the rings. But if I did the numbers correctly, you need 4700 square meters of sail per kilogram of spacecraft mass in order to hover 1 km above the A ring. (If anyone cares, that scales with the height over the ring plane divided by the cube of the distance from Saturn.)

Posted by: nprev Dec 2 2010, 05:48 PM

Apologies for resurrecting an old topic (and probably posting on a tangent to boot), but I just had a thought.

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.

Posted by: Frank Crary Dec 2 2010, 07:49 PM

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.)

Posted by: ZLD Dec 2 2010, 07:59 PM

I'm not aware of any detected meteors with Saturn either. It does seem like it would be a relatively common occurrence but I don't think Cassini would be able to pick up the flashes easily. If it were able to take a fast paced video, it would be more likely but the duration of the flashes would be so quick that a photo would likely be shear luck if even possible. As Frank said above, most particles are going to be tiny and many wouldn't cause a flash at all and those that did would be relatively dim. Now if one of the inner moons decided to kamakaze inward, well that'd be something pretty damn spectacular!

Posted by: Dysgraphyk Apr 11 2013, 07:47 PM

A new connection beetween saturn ionosphere and rings

QUOTE

Saturn’s ionosphere is produced when the otherwise neutral atmosphere is exposed to a flow of energetic charged particles or solar radiation1. At low latitudes the solar radiation should result in a weak planet-wide glow in the infrared, corresponding to the planet’s uniform illumination by the Sun2. The observed electron density of the low-latitude ionosphere, however, is lower and its temperature higher than predicted by models3, 4, 5. A planet-to-ring magnetic connection has been previously suggested, in which an influx of water from the rings could explain the lower-than-expected electron densities in Saturn’s atmosphere6, 7, 8. Here we report the detection of a pattern of features, extending across a broad latitude band from 25 to 60 degrees, that is superposed on the lower-latitude background glow, with peaks in emission that map along the planet’s magnetic field lines to gaps in Saturn’s rings. This pattern implies the transfer of charged species derived from water from the ring-plane to the ionosphere, an influx on a global scale, flooding between 30 to 43 per cent of the surface of Saturn’s upper atmosphere. This ring ‘rain’ is important in modulating ionospheric emissions and suppressing electron densities.

on http://www.nature.com/nature/journal/v496/n7444/full/nature12049.htmlhttp://

Posted by: Hungry4info Apr 12 2013, 03:31 PM

Fixed link.
http://www.nature.com/nature/journal/v496/n7444/full/nature12049.html