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Kilometer-High Waves Flow In Saturn's Rings
An anonymous reader sends along a Cosmos Magazine piece on the discovery by NASA's Cassini probe of vertical structures in Saturn's rings, 150 times as high as the rings are thick. The structures were seen because a once-every-15-years orientation of the rings caused vertical features to cast visible shadows. "NASA's Cassini probe has uncovered for the first time towering vertical structures in Saturn's otherwise flat rings that are attributable to the gravitational effects of a small moon. 'We thought that this vertical structure was pretty neat when we first saw it in our simulations,' said John Weiss, the paper's lead author at the Cassini Imaging Central Laboratory for Operations in the US city of Boulder, Colorado. 'But it's a million times cooler to have your theory supported by such gorgeous images. It makes you suspect you might be doing something right,' he added." Update: 06/17 19:29 GMT by KD : The CICLOPS team sent a note correcting the attribution of the quote; the linked article also had it wrong, and has since been corrected.
The Cassini site has a bunch of nice high resolution photos.
http://ciclops.org/view_event/110/Towering_Edge_Waves_Pop_Into_View
Go take a look. They're great!
I am involved with planning the Cassini mission and, in fact, helped plan the images in the current story.
Yet only now are we beginning to receive imagery of detailed ring structure.
You're starting from a mistaken premise. We've been getting detailed images of the rings for the entire mission. In fact, the highest resolution images of the rings to date (probably ever) occurred during orbit insertion at the very beginning of the prime mission.
Since the primary mission has ended it is apparent that obtaining detailed images of ring structure was never a priority.
Nope, rings is a major priority and drives the mission around 20%. (Depending on how you quantify that.)
All of the time has been spent on the moons, Saturn and relatively wide shots of the rings.
Again, blatantly false. Any time we're out of the equatorial plane of Saturn (as we are now and have been many times during the mission to date), we're studying the rings and the magnetosphere (and Saturn, but they tend to be a bit less insistent on this geometry). There are many close-ups of the rings available. Have you looked for them? They're all over at CICLOPS, if you do a search. Or even browse images, really.
Is resolving the ring constituents even feasible for Cassini?
No, we can't get close enough to resolve a 1-m body.
I can see from the flight schedule that close up passes of some sheppard moons will occur in 2010. Will attempts be made to image the detailed structure of the rings at this time?
Yes and no. At the time of flyby, we're in the ringplane and cannot see the rings very well at all. Near that time, I'm sure we'll take images of the rings. As we have always done.
I know the rings are largely particulate; a fog of ice particles.
Not the main rings, no. The main rings are ~30-cm to ~3-m bodies. And there is almost no way to get close enough to image these. It's not even a matter of risk, it's a matter of having to be far, far too close to what amounts to a solid wall of ring. And what good would imaging a few particles in one location do compared to destroying the spacecraft in the process? Apart from satisfying you need to see even closer up to the rings?
We have to apply for extended missions by putting together a plan and pitching what we're going to do. ("More of the same," is generally frowned upon, naturally.) If the mission is healthy and the plan seems reasonable, they'll approve it. From what I've seen (I'm still pretty young in the field), they tend to be pretty favorable to healthy missions, though, so odds seem good of extension. It's pretty much expected that missions will survive their prime missions since those tend to be conservative estimates for life expectancy.
The high gain antenna on Cassini doesn't pack away, it's a solid dish. (Unlike Galileo, then. Also, this one works...) I'm not 100% certain why they made that design choice (way, way before my time), but it has the benefit of being useful as a shield when they plot through potentially hazardous areas, like dusty rings.
And you don't really back up instruments because no one instrument is really vital to the entire mission. If we lost the ability to do IR spectrascopy, it would be quite a blow, sure. But other instruments would go on and get a lot of results anyway. You lose the engine and you're basically done.
(The one exception on Cassini is the imaging science instrument. It has the highest resolution and is regarded as vital for navigating the spacecraft. I'm not certain that they couldn't work around a failure on ISS, but they really, really don't want to. Also, RSS is basically the high gain antenna, as I understand it, so I'm not sure if it's possible to (effectively) lose RSS and still talk to the spacecraft.)
That said, NASA/JPL does everything it can to preserve the instruments because each one *does* contribute valuable and unique science. You don't want to lose any of them, of course. Fortunately, I suspect that protecting them may be a bit easier than the engineering components. The instruments tend to have very few moving parts, for one thing.