The DPS conference in Pasadena is now in full swing (and I am not there). News and press releases are slowly trickling out of that conference, from New Scientist which reported on an Enceladus theory relating cosmic rays and Enceladus' jets and warm south polar region, to public releases at the Cassini JPL site, to glogger Brad Thomson reporting on the conference for the Planetary Society. So I thought I would create a thread just for Cassini news from this conference.

Enceladus
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There is already a thread regarding the Cooper et al. theory relating cosmic rays and the jets, so I won't touch on that here. Brad Thomson went to a few of the Enceladus talks and had a few interesting things to report. First, the ISS team is now moving away from the idea that the thrust faulting seen along the south polar terrain margin as well as the overall global tectonic pattern suggests that Enceladus experienced a flattening of its polar axis (due to an increasing in its rotation rate for example), and moving more toward a regional tectonism explaination. Again, any theory regarding the south polar terrain not only has to explain the appearance of that area, but also the tectonic pattern seen in other regions as well. Perhaps Nimmo and Pappalardo's diapir theory would work best here. The ISS team also reported on the leading hemisphere terrain. Only the western margin of this terrain has been observed at resolutions better than 1 km/pixel (that will change next year, IIRC), but what has been seen is reminiscent of the south polar region, with its criss-crossing network of ridges and troughs. Another example of a "south polar-like relic terrain" is south of Diyar and Sarandib Planitiae.

Brad also reported on talks given by John Spencer, Andy Ingersoll, and Feng Tian. John Spencer gave a plenary talk on the current state of Enceladus science on Monday. One interesting tidbit was that one of the Voyagers (I presume 2 since it came much closer to Enceladus) could have observed the tiger stripe sulci had it not been for an error that prevented the acquitition of high-resolutions of Enceladus. Would be curious to know the details on these observations (Phil?). Ingersoll examined the dynamics of the plumes and showed that some of the geysers point in directions different from normal to the surface (which of course complicates my vent location idents). Not sure about the continuous source comment. Maybe this has to do with CDA's need for a moon-wide source of dust in addition to the south polar source... Feng Tian's work on ejection velocities seem to further rule out sublimation as a plume mechanism.

Saturn
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VIMS has released an image, String of Pearls, which shows a pattern of cloud clearings in Saturn's northern hemisphere. These clearings maybe related to a large planetary wave at that latitude.

The Voyager problem that prevented observations of the tiger stripes was the infamous scan platform jamming - it happened at the time of the most target-rich part of the fly-by, when rapid slews were needed to observe everything. It caused the tragic loss of high resolution mosaics of the south pole of Enceladus and much of Tethys, as well as other observations. Superhuman efforts made the instruments operational in time for the distant Phoebe flyby a week or so later.

Phil

Faint Rings Fun
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The are two press releases dealing with talks by Matt Hedman on faint rings in the Saturnian system. The first, Saturn's rings show evidence of a modern-day collision, discusses analysis of the changing structure of the outer D-ring. Changes in the spacing of ringlets and the structure of these ringlets suggest that a collision occured between the D-ring and an outside meteor sometime in the mid-1980s. In the other release, analysis of high-phase images from last month indicate the presence of faint diffuse rings in the Cassini Division as well as in the orbits of Janus, Epimetheus, and Pallene.

A number of images accompany this release, including a mosaic of Saturn when the sun was behind it last month: http://photojournal.jpl.nasa.gov/catalog/PIA08329

zOMFG!

Yeah - that is a very purdy picture indeed.

<clink>worthy!

stunning!!!!!!!!!!!

Volcanopele, don't you know whether the released image is considerably downsampled? If yes, is there any chance of getting the full resolution thing?

Borek

That is the full resolution thing. A number of the wide-angle frames were binned 2x2 onboard so there's nothing to be done there. The mosaic is still some 4000 pixels wide. I recommend getting the product directly from CICLOPS, they also provide PNG versions which are significantly smaller than TIFFs on Photojournal, while retaining losslessness.

I have asked because the big approach pan was some 8000px wide. But I understand, those were narrow-angle frames stitched together. Never mind, it's big enough

Borek

Here's my first star map version ...

Still i'm searching for Dione, Mimas and Mars.

I don't know how meaningful it is to locate stars in a large mosaic such as this because there are too many individual footprints taken over some 3 hours that star positions will be pretty distorted during that time. Some stars might appear twice, while others not even once. There's too much parallax between footprints on account of slow readout times of the ISS cameras.

As an extreme example, I think Enceladus shows up twice in the mosaic, the other occurence being slightly to the right of your labeled version.

An abstract and some interesting Bruce Moomaw comments here:
http://tech.groups.yahoo.com/group/jupiter_list/message/7515

That Saturnian panorama is pretty impressive. When I first saw the thumbnail version, I thought it was computer-generated artwork (similar to the Solar System Simulator, but with a bit more work). It took me a couple of seconds to realize that it was composed of processed real images.

One of the first things that surprised me was the near-moonlessness of this mosaic, but if you think about it, this is a very unfavorable phase angle for viewing an airless world.

That mosaic of Saturn has got to be THE most spectacular astronomical view I've ever seen. I can't find enough words to describe it.
I showed it to my colleages at work and they were also immediately blown away by it. My wife couldn't believe at first it wasn't an artistic rendering!

Absolutely beautiful -big hats off to the Cassini team

Nico

The PR states:

"This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006". Are you sure there isn't a larger version flopping around somewhere?

[Edit: The Ciclops site mentions that "The full mosaic consists of three rows of nine wide-angle camera footprints; only a portion of the full mosaic is shown here."

Anyone know how one could obtain the full resolution mosaic?]

9 frames wide by 3 frames tall at 2 x 2 binning is only 3600 x 1200 on an 800 x 800 ccd.

I'd say 3976x1332 is the full image at full resolution.

Perhaps they intend to put the binned colour onto unbinnned clear filters - but in terms of the colour data - I think we have seen it in all its glory.

Doug

The CCDs are 1024x1024 pix. Galileo's SSI had 800x800.

Given the height is three footprints which is 3x512 and the size turned out at 1330, it's reasonable to assume 15% overlap between footprints. This would give 9 footprints horizontally at 9*512/1.15 = 4007, pretty close to 3976.

I'm puzzled by this image, though, the coverage wasn't 9x3, so they obviously cheated a bit at extreme edges. Keep in mind the 165 image figure takes into account multi-filtered frames (at least 3 - IR,clear,UV, plus various exposures).

So yeah, I agree with Doug, this is as good as it gets. The extreme edges are probably devoid of significant ring material anyway.

DOH..

I actually wrote that post with 1024 x 1024 maths...then thought "Duh - Ciclops is 800 x 800 CCD's..."

0.64 Megapixels is so 1980s

Looking back at the raw jpgs - I see 7 filters for most of the patches almost all 2 x 2 binned.

IR3 short exp
IR3 long exp
VIO long
VIO short
Clear Long
Clear Short
Clear Medium Exp NOT 2 x 2 binned.

165 / 7 = 23 and a bit pointings...perhaps they dropped some of the short exposures for pointings most distant from the 'diamond ring' area.

Doug

Ok thanks. The largest size I was able to download was 2766x1364 though even though the Ciclops (Eclipse Mosaic) site states the full size version is 3986x1364. If anyone has a link to the 3986 pixel wide version, kindly post it.

I didn't even notice it until you brought it up, but the mosaics are indeed 2776 pix, not 3986. This would be in line with the above coverage map I linked to showing the complete coverage is not 9x3 but 7x3. They must have messed something up in their release. I still maintain that's the full resolution image, there is no data for an expanded mosaic, unless you drop the lowest footprint row.

Hey, "it's big enough" as has already been said.

Small correction- I did mention in my talk that I'd checked with Candy Hansen, who's now on the Cassini UVIS team and worked on the Voyager imaging team in the 1980s, whether Voyager 2 could have seen the tiger stripes or plumes if the scan platform hadn't jammed. But the answer was no- the lost highest-resolution images were still taken from north of the equator so wouldn't have seen the tiger stripes. And the phase angle on Enceladus as seen from Voyager 2 never got much higher than 90 degrees so it wouldn't have seen the plumes either. I didn't check whether Voyager 1 (which never got close to Enceladus) might have seen the plumes had it taken a distant image at the right time- it would be interesting to look into that.

It would also be fun, if someone was motivated, to simulate what the lost Voyager 2 Enceladus images would have looked like had the scan platform not jammed- we probably have coverage of the relevant bits of Enceladus by now.

John.

Voyager 1 "saw" the tiger stripes or related terrain as higher contrast albedo markings in long range approach images that were part of a distant enceladus partial rotational coverage sequence. It's clear there there was likely to be something interesting to look at there... but no possibility of looking with Voyager's northern views during relatively close approach.