I don't expect more images, why image Dione when hundreds of ring images need to be taken.

Steve,

There is now a good opnav that shows the "hole" region - http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=146810

There is a also a lone wide angle frame from the 23rd, which is odd. Makes me wonder if there are more Dione shots waiting to be transmitted.

Dione is slightly off center -- I'll bet you your lone wide angle shot is a context shot for a CIRS observation. A reminder of the various boresights:



--Emily

That diagram looks pretty accurate except for the CIRS fields of view, which in reality are offset in the direction of the round "FP1" detector- FP1 is just outside the ISS NAC field of view and the other two detectors, FP3 and FP4, are both on the right-hand side of the NAC field of view.

John.

A update Dione Map http://saturn.jpl.nasa.gov/multimedia/imag...fm?imageID=3079

Very noticeable that the feature previously known as Cassandra (~245deg West 42 deg South) doesn't show up too well on the new map. It was exceptionally prominent in distant Voyager images because of the albedo differential (and was assumed to be a ray crater)
The name Cassandra has now been used for a nearby crater by the IAU as the 'rays' with Cassini's better vision appear to be a series of tectonic features radiating from a central source.

Great to be party to the mapping of new worlds

This is some very interesting work. The first, third, and fifth pages are the most interesting:

http://www.dlr.de/en/desktopdefault.aspx/t...ry-1/51_read-1/
http://www.dlr.de/en/desktopdefault.aspx/t...ry-1/51_read-2/
http://www.dlr.de/en/desktopdefault.aspx/t...ry-1/51_read-3/
http://www.dlr.de/en/desktopdefault.aspx/t...ry-1/51_read-4/
http://www.dlr.de/en/desktopdefault.aspx/t...ry-1/51_read-5/

I've recently been playing around with the September 30th 2007 flyby PDS data. Here's the inbound 2-frame mosaic, IR1/GRN/UV3 stretched, low-res color overlaid on full frame clear images:



Here's one of the highest resolution footprints in enhanced (boosted saturation and UV channel) IR1/GRN/UV3 color, taken from 47 000 km:


Notice the small, yellowish craters. There's material for a high resolution color mosaic, but there might be several data dropouts. I didn't even attempt it due to substantial viewing geometry change. I did do the outbound global mosaic, 7 NAC frames also in IR1/GRN/UV3 color, about 90 000 km distance:




Lastly, here's a quick-n-dirty enhancement of the splat subtly visible in even more distant imagery:
Click to view attachment

Fabulous work! - I particularly like the crescent view.

Wow, that crater left quite a splat! Great work, Ugordan!

Here's the raw image merge from this post using calibrated data for comparison:

Click to view attachment

By "raw" do you mean true raw images or the "raw" jpegs?

Seconded! That splat is quite remarkable. Makes you wonder whether a darker, redder body impacted Dione, or an impactor exhumed a darker, redder layer out from under the bland icy crust.

Doesn't look like a deeper or fresher crater than others which left no splat, so I'm leaning towards the former.

-the other Doug

No, that's not the real color.

Phil

I was referring to the raw (as in JPEG) merge from that post, only done with PDS data this time.

Phil is right, that's not the actual color, it's an enhancement to show the outlines of the splat. The ejecta blanket is subtly yellowish in stretched colors - similar to the high res shot showing a small crater inside. In natural color it's effectively unnoticeable.

Amazing work.

Anything coming up for the non-targeted flyby on July 11? Looks about 87000km distance on dmuller's Cassini timeline.

Hi Steve,
Having checked out the Ciclops 'looking ahead' article for the next revolution, it appears there are no plans to image Dione on this pass. A shame, as I think some N. polar territory which has been poorly imaged hitherto would have been in view at Voyager-class distances (see SSS simulation below).

Obviously equinox studies are rightly taking precedence for the next month or so at or around periapse.

Dione will have a handful of very good passes in the XXM (if approved) so that's yet another thing to look forward to on this mission.

Jase

I spoke too soon, and reckoned without the ingenuity of the image-sequencing people....
They nabbed an opnav-range image of Dione which reveals some more detail in the N. polar region.

Range 427,997 taken on 11th July, slightly enhanced and cropped and rotated to match the solar system simulator view alongside.

Jase,

Thanks for the heads up, the new image indeed fills in northern areas in my map:

http://laps.noaa.gov/albers/sos/sos.html#DIONE

Click to view attachment

Kind of neat with the solar declination close to zero now and going towards positive.

Steve

Here's a revisited Dione crescent mosaic from October 11, 2005. Official release is here. Due to the substantial amount of saturnshine present (remember, the flyby was low phase inbound with Saturn as backdrop so practically a "full" Saturn illuminates Dione's nightside here), there's a lot of detail present on the nightside, but it's lost in the official version.



Sunstruck WAC frame for context:

Magnificent Gordan.
Your version of the hi-res crescent shows unequivocally how icy the surface actually is, rather than being composed mostly of silicates.
It's easy to forget that these moons, were they orbiting closer to the sun, would have surfaces covered with water oceans.

Wow! Not only that, but look at that looooong slump face near the terminator - there are two large craters that have been so neatly sectioned in half they look like illustrations out of a book!

P

Wouldn't the water just boil instead of becoming liquid? The idea of a liquid ocean on these moons implies an atmospheric pressure suitable to allow water to exist in a liquid phase.

If Dione were near the sun, I would expect it to resemble a giant comet instead.

Yes, I'm sure you're correct H4I - I neglected to account for the atmospheric pressure....

It would have to be large enough to have enough gravity to hold on to an atmosphere. Other than Titan (rather obviously) only Ganymede has enough mass to hold on to one, correct?

Yes and no. Keep in mind that surface temperature plays a role. In general, the higher the temperature, the faster the molecular speed. At Ganymede, that speed is faster than the escape velocity. At Titan, it isn't.

That splat is also visible in my color ratio maps and in stephans recent dione paper. Creusus is the name i think. nice to see the global view too!

that is a good "splat" all right
a few views from a mesh in blender
Click to view attachmentClick to view attachment Click to view attachmentClick to view attachment Click to view attachment
and a bump map - dem
Click to view attachment

All four Galilean moons have tenuous atmospheres. Triton and Luna as well.
All of them except Triton, if I recall correctly, are constantly replenished (else they would quickly leave).

Creusa. The flyby during Rev129 also provided some great views of that crater as well.

My first hi-res Dione (at 72 m/pix).
Filters IR3+GRN+UV3.

Heh, you have a good eye! I picked that exactly the same footprint to single out a while ago. Never did get the willpower to do the whole globe, but the lighting in this one seemed the best. Looks like I managed to upload a mirror image somehow - if it weren't for you I'd never figure it out

So this is funny
I controlled all your images, which I downloaded to my computer and I thought, that you haven't this.
Another interesting thing - We both used same image orientation!

with IR and UV the color can " be fun" to get near right

on average i use this formula -- give or take some--
------ Red ------------Green -----------Blue
(IR+ "20% green") ,( green) , (UV + " 20% green" )

10 to 30 % depending on just how FAR the IR and UV are away from the Visible

most of the time this works well

Padua Linea mosaic. Images from NAC camera overlaid over WAC frame (respective part of it).
Color from IR3, GRN and UV3 filters.
Images were calibrated by IMG2PNG (thanks Bjorn!) and warped by unwarpJ plugin in ImageJ.

Padua Linea registered and reprojected (and subsampled)!

Looks like the most recent flyby adds a bit to Steve Albert's Dione Map!

Click to view attachment

Yes looks like some northern areas in particular were in view. Do any of the raw images show this well?

The September 3rd encounter really had some jaw-droppy stuff! Here's the monster mosaic, with 22 clear-filter footprints using one of the WAC frames for control. Steve, this one is unusually precise for me so parts of it might be useful for your map, at least until the professionals release the definitive version:

Click to view attachment

Color and annotated versions with north at the top. The location of the pole is a guesstumentation, as it was Terra Incognito until a few weeks ago. I'm sure someone can correct it.

Click to view attachment

Click to view attachment

ISS managed to cram in some amazing Saturnshine coverage complementary to the mosaic, and by complementary I mean an awesome Rorschach-blot split right down the terminator. The crater in the middle is Dercennus, with the Clusium Fossae to the northwest and Eurotas Chasmata to the northeast.

Click to view attachment

Wild speculation,...I'm convinced that the area surrounding Amata is a large, badly degraded palimpsest. The name Amata was of course reassigned to a crater because the feature that had that name pre-Cassini proved to be imaginary due to low resolution. There does seem to be a big, obvious circular feature there in low sun, but since I have a habit of imagining circular features, I will just leave this vaguely misleading, conspiracy-theorist-looking graphic and shuffle away whistling....

That's Neith in the middle of the bottom row:Click to view attachment

AMAZING!

You should really change your username to "exploitimagery"

I agree Ted!

indeed, i presented my poster yesterday at DPS that showed this very same basin in my global topographic map of Dione. (I think i also showed it at the London meeting in 2008). it is about 350 km across and very visible as an asymmetric topographic ring with an offset central mound. the floor is relaxed, tho the rim and mound are about 2-3 km high.


(ps. preparing a blog on this and the other moons for later today . . . or tmrw!)

Oh that's simply gorgeous. Jaw-droppy indeed. Thanks for sharing.

Wow, thanks for the new desktop! It never ceases to amaze me what talent exists out here....

EC strikes again!!! Great stuff, always; thank you!