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volcanopele
A couple of papers on the Hyperion, Saturn's large, hamburger-shaped, semi-chaotically rotating satellite has been published in Science based on results from the September 27, 2005 flyby by Cassini. The first paper, by Peter Thomas et al., discusses ISS results at this moon. The second paper, by Cruikshank et al., discusses VIMS results. Here are a few links

Nature press release
http://www.nature.com/news/2007/070702/full/070702-11.html

Hyperion's sponge-like appearance
Thomas, P. C. et al.
Nature 448, 50-56 (5 July 2007)
http://www.nature.com/nature/journal/v448/...ature05779.html

Surface composition of Hyperion
D. P. Cruikshank et al.
Nature 448, 54-56 (5 July 2007)
http://www.nature.com/nature/journal/v448/...ature05948.html

NASA Finds Hydrocarbons on Saturn's Moon Hyperion
http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=758

Cassini Scientists Wring Out The Details On Spongy Hyperion
http://ciclops.org/view.php?id=3303&js=1
nprev
Fresh off the JPL presses:

http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=758
ugordan
There's already a thread open on the subject here.
volcanopele
I've merged these topics
nprev
Cool....sorry for the mis-post, all!

From the CICLOPS article: "According to the researchers, impactors smacking into Hyperionís porous outer layers form craters more by compressing the surface than by blasting out material, as they do on denser bodies." Strange. It almost sounds like it's made of styrofoam or something like that!

Hyperion might be more like a comet in terms of composition than like a "traditional" icy moon...what bothers me about that thought is that it has one hell of a lot of craters...is this actually an errant KBO subjected to the ravages of the inner Solar System but kept too cold to erase its history?
belleraphon1
"The low-albedo material has spectral similarities and compositional signatures that link it with the surface of Phoebe and a hemisphere-wide superficial coating on Iapetus."

I have always felt there was some connection because of all the strangness in this region of the Saturn system..... Hyperion's unique structure, Iapetus dark smear, even the impact like appearance of Elba and Senkyo on Titan's leading hemisphere..... is there some connection beyond the hydrocarbon dust? Did some catastrophic event mark all the bodies?

Craig
Littlebit
The CICLOPS article states that the natural color of Hyperion is a 'reddish tint". Earlier articles have identified 'red' parts of Phoebe as being ferric iron. http://www.solarviews.com/eng/phoebe.htm Are the 'spectral similarities' of Hyperion and Iapetus with Phoebe rust?
ugordan
As I understand, Iapetus' and Hyperion's color is mutually a much better match (save for significant albedo difference) than either is to Phoebe.
volcanopele
Littlebit: Red bits on Phoebe? Where? As far as I know that moon is pretty greyish with no color variations (in the visible). Are you referring to the colorized VIMS images of Phoebe?

belleraphon1: Between Iapetus and Hyperion, sure, why not. I think connecting it to eastern Aztlan (the area surrounding Elba Facula) is a bit of a stretch. Yeah, keep in mind, the brightness distribution is "evolved", due to dark particulates settling in the area. Titan != Ganymede (no matter how much their interiors are similar) wink.gif
ugordan
QUOTE (volcanopele @ Jul 5 2007, 06:29 PM) *
Red bits on Phoebe? Where?
That's what I was wondering this whole time. Back in 2004, before Cassini encountered Phoebe it was said it had a reddish tint to it. Try as I might, I couldn't detect a trace of red in color images CICLOPS released. It was totally gray for all practical purposes. I'm interested in finding out who started this Phoebe-is-red story in the first place.
volcanopele
Just flipping through the composition paper, a few highlights:

1) The dark crater floors show shallower H2O absorption bands compared to the higher albedo crater walls, where higher concentrations of crystalline water ice was observed. The dark material also has an additional absorption band at 2.42 microns, like the result of higher concentrations of CN-bearing compounds, most likely Potassium cyanide (so DO NOT ingest Hyperion dark material!!!). A similar signature was observed in Cassini Regio on Iapetus and on Phoebe.
2) Dark material on Hyperion contains more complexed CO2 than in the higher albedo regions, based on an absorption band at 4.25 microns. The bright regions contain a mix of pure CO2 frost/ice and the complexed CO2. CO2 concentration varies across the satellite with no apparent correlation with geologic structures.
3) Polycyclic Aromatic Hydrocarbons (PAHs) may have been observed on Hyperion based on a possible absorption band at 3.28 microns.
4) The results at Hyperion can be explained with a country rock consisting of a heterogeneous mixture of H2O and CO2 ices with deposits of cyanides and nitrogen-rich organics filling in some crater floors.
5) The closest spectral match to Hyperion's surface is a mixture of H2O ice and the material in Cassini Regio on Iapetus.
Littlebit
QUOTE (ugordan @ Jul 5 2007, 11:32 AM) *
That's what I was wondering this whole time. Back in 2004, before Cassini encountered Phoebe it was said it had a reddish tint to it. Try as I might, I couldn't detect a trace of red in color images CICLOPS released. It was totally gray for all practical purposes. I'm interested in finding out who started this Phoebe-is-red story in the first place.

It predates Cassini:
http://www.solarviews.com/eng/phoebe.htm
"At that distance it was only a vague dark shape with some lighter patches and somewhat red in color."

The spectral analysis indicates a detectable amount of ferrous Iron scattered across the surface, so I am still wondering if parts of Phoebe have at least a dark reddish hue.

http://www.solarviews.com/raw/pia/PIA06400.jpg

Cyanide could explain the red of hyperion - could somebody please ship a Raman spectrometer to Cassini, so we can nail down this nondescript dark stuff? How long would it take to Fedex to Saturn?
ugordan
For reference, here's the color rotation movie of Phoebe Cassini took on approach. Apart from slight color fringing due to rotation/registration there's really not much color there.
ugordan
I've completed another Hyperion movie from the imaging sequence Cassini took spanning 2006-06-27 13:47 UTC through 2006-06-29 08:13 UTC that hit PDS recently. It's composed of 17 narrow-angle filter sets, 15 of which are IR1/GRN/UV3 filters processed to match the two natural color ones.

Magnified 2x and preserving relative brightness (shows large phase angle brightness variation). The time intervals are discontinuous and focus on far approach images, closest approach and outbound sequence. A snapshot of the movie at closest approach is the only natural color image of Hyperion the imaging team has released so far. Their famous false color mosaic is so widely distributed people probably assume that's how Hyperion really looks like...
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