[X] My Assistant

[alan]

Six days to go until Enceladus flyby ( E2? ) at 175 km

[Decepticon]

Very nice.

I wonder how enceladus magnetic field/south pole lines up with those "4 cat scratches"

[Decepticon]

Another attempt at a coloring.


I'm not sure how this is done correctly.
Is there a site that explains how to this in adobe?

[tedstryk]

I think that we got some pretty good coverage of the North Polar region on the leading hemisphere from Saturnshine images. As for the other side, the highest resolution Voyager set covers much of it. I am working on a super-res image.

[pioneer]

I don't know about anyone else, but I haven't found any signs of ice volcanoes or guysers yet.

[scalbers]

I shamelessly stole Steve Albers' cylindrical projection of Enceladus (thanks!) and made this polar projection of the southern hemisphere (just using the polar coordinates function in Photoshop):

[attachment=930:attachment]

Incidentally, the saturnshine images from the last imaging sequence on this orbit show new territory west of Voyager 2 coverage which could be added in to the northern hemisphere of the map.
Phil

Phil,

Thanks for the polar view - interesting to see it all laid out. I'll probably be working on adding one or more additional sunlit images from this flyby, particularly at high southerly latitudes. After that I can see what would be involved in some of the Saturnshine images.

[tedstryk]

Here is all I could do...the images are at impossibly different angles.

[alan]

Bizarre boulders litter Saturn moon's icy surface

On 14 July, Cassini swooped in for an unprecedented close-up view of the wrinkled moon. Its Imaging Science Subsystem (ISS) camera has since returned pictures of a boulder-strewn landscape that is currently beyond explanation. The "boulders" appear to range between 10 and 20 metres in diameter in the highest-resolution images, which can resolve features just 4 m across.
“That’s a surface texture I have never seen anywhere else in the solar system,” says David Rothery, a planetary geologist at the Open University in Milton Keynes, UK.
Cracks crisscross Enceladus's surface - possibly as a result of the moon being repeatedly squeezed and stretched by the gravity of Saturn and other moons nearby. But Rothery points out the boulders avoid - rather than fill - the cracks. This might indicate that the fracturing took place after the boulders had already formed.
Alien landscape
John Spencer, a Cassini team member at the Southwest Research Institute in Boulder, Colorado, US, agrees that the images are puzzling. “You would expect to see small craters or a smooth, snow-covered landscape at this resolution," he told New Scientist. "This is just strange. In fact, I have a really hard time understanding what I’m seeing.”

http://www.newscientistspace.com/article.ns?id=dn7692

I wonder what happens when a mixture of water and ammonia freezes. Would some of the water freeze first, forming ice boulders, leaving a more concentrated mixture of water and ammonia behind? If a mix of icy boulders and liquid water-ammonia reached the surface, the liquid at the top could vaporize leaving the boulders behind.

[edstrick]

Post-Voyager, there was a spate of studying the potential of ammonia/water volcanism. Assorted studies of the very complex phase diagram of the two ices and the physical properties of melts. Some melts at low temperatures are very runny-liquid, while higher temperature melts with a different ammonia/water molecular ratio is like soft-taffy! Certainly there were a number of abstracts in the yellow-books: LPSC conference Abstracts from the period. Where final papers were published, I don't know.

Note that it's unlikely ammonia will be dectected on Enceladus's surface even if eruption is happening recently in geologic terms.. It takes hard UV to split oxygen and hydrogen. Quite soft UV, of which sunlight has a lot more, is all you need to split nitrogen and hydrogen. Exposed ammonia ice will have a quite short <years? decades?> lifetime.

[Roby72]

Any news about the INMS and UVIS observations ?

[Gsnorgathon]

...
Exposed ammonia ice will have a quite short <years?  decades?> lifetime.
...

I've seen the expected lifetime of methane in the martian atmosphere mentioned all over the place, but never the expected lifetime of exposed ammonia on any out solar system body.

[Guest_Myran_*]

Gsnorgathon said: I've seen the expected lifetime of methane in the martian atmosphere mentioned all over the place, but never the expected lifetime of exposed ammonia on any out solar system body.

Not me either, but I do remember from one article that the author expected that the ultraviolet radiation from the sun would have broken down ammonia on the surface of Saturn's smaller moons over time.

But again Pluto's moon Charon is thought to have ammonia ices,
Evidence for Crystalline Water and Ammonia Ices on Pluto's Satellite Charon

Even without more exact numbers I can still say to edstrick&Gsnorgathon that it would be far longer than years or decades, rather millennia to millions of years.

[Decepticon]

New update.


http://ciclops.org/view_event.php?id=23

[dilo]

New update.
http://ciclops.org/view_event.php?id=23

Yes, absolutely magnificent images, but very slow link in this moment (too traffic, maybe)
I enhanced colors here, pretty nice and interesting:

[volcanopele]

The magnetometer instrument confirmed an atmosphere at Enceladus during the July 14 flyby. Data from this flyby and modeling work of previous data shows that the atmosphere is concentrated over the south polar region and is much more rarified over the rest of the surface.

The plot thickens...

http://www.pparc.ac.uk/Nw/enceladus_flyby.asp

http://volcanopele.blogspot.com/2005/07/pr...instrument.html

[volcanopele]

UVIS detects Enceladus' atmosphere (and also sees the same spatial non-uniformity that MAG found):

http://photojournal.jpl.nasa.gov/catalog/PIA06431

And now for the punch-line: CIRS found a hot spot near Enceladus' south pole:

http://photojournal.jpl.nasa.gov/catalog/PIA06432