Rhea Revisited, Mosaics from the 30 August 2007 Encounter Options

[dvandorn]

Ya know, EC... back when the forum was deciding (in some poll or another) that Rhea was undoubtedly the most boring single object in the Solar System, I vehemently disagreed, noting many of the features you're pointing out in these excellent images. Especially the massive proliferation of what are either endogenously-controlled graben or exogenously-controlled crater chains.

Thank you very much for bringing into focus this quite fascinating satellite.



-the other Doug

[volcanopele]

It is still the most boring moon in the solar system (that meets the spherical requirement for being a planet). But no one says that boring can't have some beauty to it.

[Mariner9]

My vote for the single most boring object in the solar system is a tie between Dr. Phil and Regis Philbin.

In third place, Rhea is the solid contender.

That being said, these mosaics are beautiful. Especially the rayed crater. Thanks for processing these and sharing.

[tedstryk]

Wow, strange coincidences. After too much beer, I almost posted to "inform" exploitcorporations that the images were of Rhea, not Dione...not sure why I was thinking Dione.

[belleraphon1]

Absolutely stunning, EC!!!!! As always.

Rhea is almost like the control blank for the Saturn system. Heavily pelted and now serene(?!) under all those scars.

Craig

[ugordan]

Superb mosaics, Exploitcorporations!

(psssst....I'd like to see that whole mosaic in color sometime. If anyone can do it, it's you.)

I'm not sure I'll be doing the whole huge color mosaic soon, too many frames and Rhea rotates considerably during the one or so hour it took. Here's just one section in false color, contrast-stretched and I subdued the hues a bit. Removed the Saturn backdrop as perspective change between footprints caused registration problems.



It looks pretty nice, even if I do say so myself. Rhea may be the most boring moon, but I prefer it over say Dione as it's actually got some nice brownish hue to it. Dione is greenish in false color; yuck!

[centsworth_II]

[stevesliva]

The closeup view in the upper right corner begs a few questions...."Is all that powdery craterless freshness landslides? What's up with that peppering of tiny craters near the central peak? Are those layers in them thar walls?"

Some massive settling on the left post-impact means fewer secondary impact craters than on the right?

[ugordan]

Speaking of impact deposits, did anyone take note of a string of dark stains seen vertical (splitting the mosaic right in half) in my above composite? Here's a crop and enhancement at the original geometry, equator is roughy horizontal:


They're very faint, but are black-ish unlike the rest of Rhean regolith. Apparently they can only be seen in lower phase imagery due to very low contrast. Do we know of a crater whose ejecta might have produced this (although ejecta on Rhea seems brighter than the surroundings) or could this have something to do with the hypothesized ring? I found the equatorial orientation somewhat interesting, otherwise I'd pay no attention to this.

[ElkGroveDan]

It has the appearance of a massive landslide or escarpment.

[stevesliva]

They're very faint, but are black-ish unlike the rest of Rhean regolith. Apparently they can only be seen in lower phase imagery due to very low contrast. Do we know of a crater whose ejecta might have produced this (although ejecta on Rhea seems brighter than the surroundings) or could this have something to do with the hypothesized ring? I found the equatorial orientation somewhat interesting, otherwise I'd pay no attention to this.

Very very interesting. So this obviously can't be Rhea. I don't really see deposits like that forming linear features in other directions.

[Exploitcorporati...]

Here's the parting global mosaic , with the poorly registering Saturn backdrop replaced. 24 clear filtered images are used, with one WAC image plugging gaps in the western limb.

ISS_049RH_REGMAP001_PRIME:

[jasedm]

^ Magnificent!
I've often felt slightly guilty at vicariously enjoying the fantastic image products showcased here, so I've recently bought Photoshop and am slowly teaching myself the basics - hopefully I'll be able to post some mosaics myself at some stage.

Ugordan - very intriguing dark markings near Rhea's equator (and well-spotted once again), it would be interesting to see how closely they match with the supposed orientation of any ring material.
There seems to be a large amount of dark material in the Saturn system (Phoebe, Iapetus, and at the bottom of craters on Hyperion, Janus and Epimetheus, to say nothing of regional differences on Dione and Tethys) I wonder how similar the material is spectroscopically?

[tasp]

The Gehrels Asteroid book indicates the Iapetan dark stuff is quite similar to D type asteroid spectra.

IIRC, we also have Cassini data indicating the Hyperion and Iapetan dark stuffs are quite similar to each other.

Also note, the Iapetan dark stuff shows a visual subtle color shift going from east to west (or west to east if you think about it).

To me, the color shift is kind of a problem for the folks theorizing the dark stuff is evaporative residue. Particularly if there is a mechanism for an externally sourced dark material that might sequentially apply (react?) longitudinally in synchrony with Iapetus' position around Saturn.

[hendric]

Sorry for being lazy/absent/ugly/electrocuted/ect. I lurk religiously and post stingily. Except for today.

We've been missing you. Now get over to the HAPS thread pronto.