Rhea, Dione and Mimas

[mmcirvin]

A nice three-moon shot taken as a visible-light color separation:



This should be close to a natural-color picture. The relative positions of the moons and spacecraft moved significantly between shots; I chose to use the positions as shown in the blue-filter image. Mimas may be a little further off in color than the rest of the picture, since it was out of frame for the red-filter image so I had to make do with the other two channels; I duplicated the green data for the red.

Mimas's elongated shape is fairly apparent here; Saturn is off to the left.

Comments

[glitter-ninja.livejournal.com]

I know I said I wouldn't do this, but -- OOH! COOL! I dig space photography, and it's so much clearer than it was when I was in high school, it's just fascinating.

[mmcirvin.livejournal.com]

This one of Titan and Dione (http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1439) is nice too.

[ronebofh.livejournal.com]

Is the line the rings?

[mmcirvin.livejournal.com]

Yes, that's the rings. Because Cassini didn't swing by Titan to alter its orbit this time, this orbit is almost exactly like the previous one, very close to the ring plane. So the rings appear either edge-on or very close to it, and it makes for a lot of dramatic multi-moon/ring pictures.

I was confused for a while about why the terminator line on Rhea seems to have more curvature, given that the sun's rays are effectively parallel here. I think it's a perspective effect. Cassini is not so far from Saturn here that the moons are all effectively at the same distance. Mimas in the upper right appears to be the furthest from Saturn, but it's actually the closest to both Saturn and the camera by a considerable margin; Dione is further away, and Rhea on the left is further still.

[mmcirvin.livejournal.com]

A large part of making this look nice was just figuring out the most artistic way to rotate and crop it. (South is up, in case you're trying to identify surface features on the moons. I think the triangle of prominent craters near the terminator of Dione are Dido, Antenor and Romulus; Remus is just barely into night. The two longest wisps sticking over the horizon are Palatine Linea and Carthage Linea.)

[ex-askesis860.livejournal.com]

I read this (http://badnewshughes.blogspot.com/2004/08/diary-of-indignities-fun-with-science.html) today, and thought of you. Why? Because you "champion the former perspective." It will make sense in context.

[mmcirvin.livejournal.com]

Thanks...

Champion it, maybe. I get slightly embarrassed by comments like this because, as I have to repeat periodically, I'm not an actual scientist; I'm just a washout with a degree. And several people on my friends list are actual working scientists, so I feel like I'm taking something away from them by getting all Dr. Science here.

[ex-askesis860.livejournal.com]

I know a lot of real scientists, too. Dating one, even. And they usually didn't want to talk science for the same reason I don't want to talk AI - it's after 5. You're not taking anything from them. The way I see it, you're giving them something: the fan-like attention they deserve for being the rock stars they are.

[mmcirvin.livejournal.com]

Sometimes I think I was too captivated with the romance of science to actually hunker down and spend thirteen hours a day working on something extremely specific, which is what you have to do in order to make real progress. Whereas in my adopted profession I can get that keyhole focus sometimes, in part because I don't have much of the trained computer-science academic's yearning to work on something more conceptually interesting. (Wherever I go I seem to get a reputation as a tenacious bug-smasher.)

In one of his many autobiographical introductions, Kurt Vonnegut was talking (as he often does) about his ambiguous feelings toward his brother Bernard, who was a prominent expert on thunderstorms. He said once that he'd complained to his editor about how onerous a task writing had become for him, and the editor quoted somebody as defining a writer as somebody who hates writing, and added that "the blacksmith always hates his anvil". He repeated that to Bernard and got only puzzlement, since Bernard's whole career had been "a continuous love affair with his anvil" (this also worked as a pun on the characteristic shape of thunderclouds, I suppose). Vonnegut had the idea that all scientists were like his brother, which fed into his strange combined envy, admiration and fear of scientists, but I think it's considerably more various than he thought.

[mmcirvin.livejournal.com]

...In the specific case of Cassini I do feel like I'm helping to deliver value for money back to the public. This long field trip to Saturn is expensive as unmanned space missions go; it cost a lot of American and European tax money, and the launch was associated with some public controversy as well, but trips to someplace like Saturn do have the advantage that they deliver many visual wonders that anyone can viscerally understand to go along with the data for the scientists. And while not everyone may consider that worthwhile, enough people do that, say, the Hubble Space Telescope has gone from embarrassment to beloved icon largely on the strength of astoundingly lovely public photo releases.

At this point, the haul of wonders from Cassini has already been so immense that the mission would be impressive even if the spacecraft failed tomorrow. And it's important to remember that, though the Huygens landing is over (and got some of the usual "it's just a picture of rocks" ridicule in the media), and the close inspection of the rings during Saturn orbit insertion was a one-off thing, the Cassini tour is really only just beginning. If you look at the whole multi-year plan, there is cool stuff to come that is going to blow away much of what we've already seen, and if it survives that long (no reason why it shouldn't) there will surely be an extended mission as well, in which the mission planners are likely to be willing to take bigger risks for spectacular payoff.

The only moons that have had extreme close-ups are Phoebe, Titan and Enceladus; all the major moons except Mimas are going to get pictures about that good during the primary mission (and there will be much better pictures of Mimas than we've seen so far). Those jaw-droppingly weird pictures of Iapetus on New Year's Eve are nothing compared to the ones that are going to come back during the real flyby in September 2007. There are going to be pretty good pictures of Hyperion this summer and a close flyby in the fall. Essentially the whole surface of Titan is going to be mapped in the infrared, and a large chunk of it in radar (full Titan mapping in radar may well turn out to be an extended-mission priority, given how great those radar images have turned out). They're talking about trying to get radar maps of the Huygens landing site. And when Cassini starts looping way out of the ring plane in 2006-07 and again in 2008, I promise you the pictures of Saturn are going to be all over the news.

Also, we've really only seen a tiny fraction of the scientific results from the data that have already been collected; JPL dumps raw camera images on the Web almost as they come, but the camera is the exception; there are many cool pictures already gotten by the VIMS, UVIS and radar teams that nobody else has seen yet.