Rev 49 - Aug 9-Sep 14, 2007 - Iapetus I1, The only close flyby of Iapetus Options

[Holder of the Tw...]

What an extreme day.

I start out elated when I see that the first NAC images of the ridge were right on target.

Then I go home three hours ago with the latest news that the global coverage is toast, and I'm feeling kinda miserable about that.

I come back here and just a few minutes ago find out that things aren't all that bad. Still a little sad about the VIMS global (and rooting for another pass the EEM), but I least I won't have to compose a heartfelt condolence to Mr. Albers.

Then I see the latest images.

And... I... am... just...

STUNNED!!!

[belleraphon1]

Duh!!!!!

The white stuff IS virgin snow if it is the result of the dark stuff causing water/co2 ice to sublimate and migrate to colder surfaces.

Really going to bed now.

Craig

[tasp]

My take on the black stuff:

Surfaces that achieve a minimum angle to the sun's rays turn dark.

Iapetus is a thermographic printer.

(And the minimum angle is related mathematically to latitude and longitude. Angle smoothly increases east and west from a point centered halfway between sub-Saturn and anti-Saturn points on the leading hemisphere. Moving north and south of the equator, the angle again smoothly increases. Light and dark regions can change at the same scale the surface angle changes right down to the resolution of the Cassini camera.)

Find out the sun angle on these pictures and sight across the dips and dales and hills and vales.

It's all geometry and sunlight.

[GregM]

.

[Exploitcorporati...]

I broke my swear jar and ate both the contents and the glass fragments alike with a garnish of happy obscenities in as many languages as I could babel fish for. I've been in the process of moving back to Seattle after a short absence, so I've missed much of the excitement until this morning...I can't even think of an unoffensive acronym to encapsulate just how hard my jaw hit the floor with the sample of images released thus far. Special thanks to Ugordan for the view of Saturn from here (18x now...you should start up a wallpaper surcharge here). See you all here soon. BTW...my money's on the white painted over black now.

[David]

On the white/black question: could it be that neither of these substances is the underlying surface -- i.e., that there is both a "snow" coating (similar to other bright icy moons) and an "ash" coating, and that, depending on surface conditions -- topography and external heating -- you can get snow over ash, or ash over snow?

In that #13 image, however, while I can imagine conditions that would give us those patterns as snow-on-ash, I can't come up with anything that makes sense for ash-on-snow. But I think we've seen other, earlier images where ash-on-snow made more sense.

[tasp]

Just for fun (and maybe a bit more), here's a photo negative of the amazing splotch/snowdrift picture:

Attached thumbnail(s)

 

[tasp]

OK, now think about that picture. The most intense sunlight (averaged over 40 days) is striking the white parts now. Lesser levels of illumination strike all the rest of the terrain.

Everything that is white has parallel sight lines.

There is no white in the shadow of white anywhere.

[Rob Pinnegar]

More images have just come down the pipe. Quite a few more, actually.

These include some amazing shots of what look to be two of the white Voyager Mountains.

[volcanopele]

Highest resolution image: http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091974.jpg
Ray Crater: http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091978.jpg
Lots of little craters: http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091970.jpg

[tasp]

It 'works' on the other picture too:

Attached thumbnail(s)

 

[nprev]

Just had a thought...IF (and only if) white-on-black is correct, and IF (and only if), the white stuff is exogenic and presumably from a source in Saturn's vicinity, and IF (and only if), Iapetus is a captured object, THEN how many more pitch-black, virtually invisible Iapetii may be lurking undetected in the outer Solar System, unbound to major planets...

Three "IFs" usually is a death knoll for any theory...just thought I'd scare you all! (Congrats on the Seattle return, EC! )

[David]

The curved edges and bays in the "snow" region in #14 (http://ciclops.org/view.php?id=3764) remind me of the shapes of retreating glaciers. The inverse pattern, the shape of the "ash" region, doesn't make much sense on its own.

tasp, I'm not sure I'm following your argument. Do you think you could rephrase it for a dullard?

[Rob Pinnegar]

Uhhh... whaddaya call *this*???

http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126253

[Edit: I just tried clicking on this link and it didn't work... the image I'm looking at is N00091956.]

[nprev]

Rob, can you post it for us image illiterati?