[X] My Assistant

[Decepticon]

Here's a nice look at Rhea. http://saturn1.jpl.nasa.gov/multimedia/ima...9/N00030797.jpg


Tethys @
http://saturn1.jpl.nasa.gov/multimedia/ima...9/N00030798.jpg

[Gsnorgathon]

Well, looking at the feature at upper left, I see what you're talking it about. It definitely looks crater-chain-like ("catena-like"?) especially at the far end. The fact that most of the features you've highlighted have a similar orientation still suggests structural control to me. :@P

[dvandorn]

Well, looking at the feature at upper left, I see what you're talking it about. It definitely looks crater-chain-like ("catena-like"?) especially at the far end. The fact that most of the features you've highlighted have a similar orientation still suggests structural control to me. :@P

Yeah -- most (though not all) of the crater chains *do* seem to be organized along similar orientations relative to Rhea, it's true. And that does give them the appearance of being endogenically controlled.

I have an image, however, of some type of gravitational interaction flinging a stream of ring particles out of their orbits and out into the realm of the icy moons. Assuming there was no out-of-plane vector associated with the interaction, such a stream of particles would strike a moon along the ring plane, leaving chains of craters in its wake. The fact that these crater chains are no longer aligned with the ring plane could invalidate that theory, or could simply mean that Rhea's orientation to the ring plane has changed since a majority of the crater chains were formed.

On the side of structural control, we've seen these kind of "cracks" in the crusts of most of Saturn's icy moons, though in most cases they don't appear to be formed by chains of individual craters. And as they say, zero, one and many are significant findings, but "a few" means you probably don't have a complete dataset. In other words, if two other Saturnian icy moons display endogenic cracks modifying their surfaces, and we see what appear to be similar (though not identical) cracks on Rhea, the odds are high that the processes are interrelated, if not the same...

I think the jury's still out as to the formation of these crater chains, but the more data we collect, the closer we get to coming up with better theories...

-the other Doug