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Headshot of Emily Lakdawalla

Mimas and Pandora dance

Posted By Emily Lakdawalla

15-05-2013 17:02 CDT

Topics: Cassini, pretty pictures, amateur image processing, Saturn's small moons, Saturn's moons, Mimas, Saturn's rings

I've been out of town for a couple of days and am overwhelmed with work and an overflowing email box. So what do I do about that? I ignore what I'm supposed to be doing and play with Cassini raw image data, of course. Here is a "mutual event" of Mimas (the bigger moon) and Pandora (the outer shepherd of the F ring).

Mimas-Pandora mutual event

NASA / JPL / SSI / Emily Lakdawalla

Mimas-Pandora mutual event
Cassini watched Pandora and Mimas dance on the far side of Saturn's rings on May 15, 2013 at roughly 16:30 UT.

The original set of images was centered on Mimas but when I animated it like that, it was hard to tell what the rings were doing. So instead I aligned the frames vertically on the edge of the A ring, which makes it clearer that you're seeing the rings "close up." Cassini's orbit is currently highly inclined (it's tilted more than 60 degrees). At the time that Cassini took these photos, it was near periapsis and plunging rapidly from north to south; it would cross the ring plane just 8 hours later. So even though Mimas appears to be moving vertically in the animation, it's not; you're actually seeing an effect of Cassini's vertical motion.

Watch Mimas closely and you'll see it's rotating, too. If you notice a falling donut at the bottom of the image, it's an artifact -- a mote of dust somewhere in the camera's optics.

See other posts from May 2013


Read more blog entries about: Cassini, pretty pictures, amateur image processing, Saturn's small moons, Saturn's moons, Mimas, Saturn's rings


Bob Ware: 05/15/2013 07:39 CDT

That's a really nice piece of work Emily! Thanks for the effort! The "movie" had a pretty good sized chunk of rotation in Mimas too. It's also nice to see that the Death Star (Mimas) did not zap Pandora! LOL!! (dated myself!) Thanks again!

Kalle Centergren: 05/16/2013 02:44 CDT

Emily you got it all wrong, thats no moon, its a space station!

Bob Ware: 05/16/2013 10:18 CDT

Kalle - Thanks for the backup!!!! LOL!!!

Mike Martinez: 05/16/2013 11:03 CDT

Too bad it didn't show when it crossed the ring plane to the other side (60 degrees in relation to the ring plane. Would it have been possible to have seen individual particles in the nearest ring to Cassini?

Tam Mallory: 05/17/2013 08:18 CDT

Man-you're good!!

Emily Lakdawalla: 05/17/2013 10:47 CDT

Mike, no, they keep Cassini sufficiently far from the rings that it will never (hopefully) be close enough to ring particles to actually photograph individual particles. The narrow-angle camera has a field of view of 0.006 radians, or about a third of a degree -- it's a very tight beam, and consequently the things it photographs are much farther away than they seem.

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