Beautiful image of Dione



If Dione didn't have those white streaks it would look a lot like Iapetus

That reminds me of a Voyager picture.

Some new Dione images are up...

Stitched the available imagery - 155kb
http://mer.rlproject.com/dione_dec15th.jpg

WOW!

And that was a non Targeted flyby!

Is this just the beginning? What is the resolution we are dealing with? WWWWWOOOOOWWWWWW!!!!!!!!!!!!!!

Good stitch Doug. I still don't know how to align the images as well as you did, but I deinterlaced the right part of this image:

Very nice work, Doug. The resolution on those images is 430 m/pixel.

BTW, doug, which filter did you use? If you used the IR1 filter, then the lower right frame was summed. All the others were not.

The IR1 filter. It's not a perfect stitch - just rushed it together to have a look at the full picture I've deinterlaced all four images, and resized up the bottom right frame (didnt figure that that's what it needed ! works a treat though ) and thought I'd try using the same pan program I use for my MER pics - PTGui.

It works a TREAT!! I just set the f.o.v. of the lens to be 1 degree (I'm not sure what it actually is - but I figured that 1 degree is nominally very very small, and small enough to not inflict and sort of distortion on the image as one would at 16.6 or 45 like with MER ) At first try - it classified the control-point accuracy as 'too good to be true' at less than half a pixel I've never EVER had that with ANY other pan I've worked on, be it MER, MPF, or normal digi cam stuff from this planet

http://mer.rlproject.com/dione_dec15th2.jpg

Now THAT - is a perfect stitch


Doug

WOW, even better. Would you mind if I sent that to a couple of team members?

Are there still more images of Doine waiting to be transmitted (or at least released on the Raw Images page?) It would seem based on the use of interlaced compression that these are the first of many.

Wow.
Is that straight line near the terminator real or an artifact?

It appears to be a real crack within Carthage Linea.

I was also wondering about the slight diagonal lines near the center of the image. Looks like it's scraped with a brush. I'd be freaked out if that wasn't an artifact of some sort...

I thinks it from the lines in the raw image.
http://saturn.jpl.nasa.gov/multimedia/imag...6/N00025776.jpg

Will there be any more Doine images?

There should be some lower resolution frames in multiple filters coming. The observation used by Doug is all in the raw page.

They are here!

Alot of the images have alternating lines of data missing on the right side of the frames...whats causing that? I've seen it on quite a few of the images,

This image is a must see:

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29076

Damn, beat me by 2 minutes

Oh YES! Fantastic:

Hmmm, these two are strange:

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29078
http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29077

Was cassini firing its thrusters as it was snapping these pictures?

don't know But we did get a clear version of that view

Are these fractures from tidal forces?

Dinoquakes

It's likely that the specific filters used for those images required fairly long exposures and as Cassini was tracking Saturn during the exposure anything else in the image will have moved and appear blurred.

In the first image of dione that is smeared the clouds on saturn are not smeared, it must have been tracking on saturn

Of course you can - hell - you guys took the pictures I just piss about with them

New Dione image




Makes an interesting and exciting diversion from MER images It seems possible to get a LOT more information out of the cassini raw jpgs than the mer ones. Even when a cassini JPG appears totalyl whited out - using levels you can - more often than not - get something back.

Doug

Doug, your two Dione images are exquisite. The first (stiched) one is already my new wallpaper.
A gazillion thanks, you 're

I can't wait to see global maps of dione. Is anyone working on a Updated Voyager/Cassini Global map?

you know....it's great to be here! some amazing work!

Wow. That's an amazing photograph.

Would anyone be willing to provide a link to a description of the different filters used by Cassini, and perhaps another with an explanation of the file naming conventions used for the raw images?

This feiImageID=xxxxx stuff looks pretty cryptic to me. Am I missing something?

This same information from the MER mission was relatively easy to obtain.

Unfortunately - there isnt the same MER convention. They're just sequential numbers

However - on the page describing each frame is a descriptor

i.e.

http://saturn.jpl.nasa.gov/multimedia/imag...&storedQ=762004

Lots of piccies -all of the same thing - so you can guess, lots of different filters

What you WANT - is the ones with CL1 and RED, GRN and BL1

On that page - they start with the last one - and the first two of the following page...thus

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29068

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29067

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=29066

You often find that if there are a LOT of images of the same thing ( i.e. it's been taken thru lots of filters ) - if there ARE Red,Green and blue then they are often the 5th, 4th and 3rd from last of the sequence - or there abouts!

Doug

Doug,

Hope you don't mind, but I just wanted to say a big, and overdue, thank you for sharing all the amazing pics - first of Mars, and now Saturn, etc - you take so long producing. I'm sure that I speak for many people who visit this Forum when I say that your site is as much a part of our browsing routine now as the official NASA MER and CASSINI websites, and you constantly amaze us with the quality of your work here. Each time I go online and visit the site I feel spoiled by the latest wonders from you, and very grateful to you for sharing them with us.

Wider - and official - recognition of your imaging work is long overdue.

If they were, I'd expect them to be centered on the anti- or sub-Saturnian hemispheres but instead they are roughly centered in the trailing hemisphere. My thinking is that early in Dione's history (given that there are a few large craters post-dating the fracturing) a diapir of warm ice inpinged on the brittle icy crust from below. The extent of the volcanism was just a round of outgassing that produced the dark diffuse material (dark in UV). Then as the stresses increased, the crust fractured as you see it today. This must have been early, maybe ~4 Ga, or there abouts. that's just MY idea, I still haven't vetted that through the team and I am certainly no expert on the history and physics of mid-sized icy satellites. I am just trying to come up with a way to causing such extensive fractuing focused on one area (and dark material in one area) yet have much of the rest of the satellite look as dead as a doornail.

That's part of a huge sequence of images in MANY filters. I am actually surprised to see that Doug hasn't tried to play around with that.

If you are Doug, and just not done yet, use the two UV filters (UV3 and UV1) as two of your filters then select what ever you want as red and be ready for a great view

I plan to do a quick and dirty (similar to the Tethys map I posted a few weeks ago in a different thread) cylindrical map of Dione as soon as I can but unfortunately I probably do not have time to do so until next week at earliest.

Check out
http://photojournal.jpl.nasa.gov/catalog/PIA06162

I knew it!!! I knew they had to take a global mosaic. Wonder why all the raw data wasn't released. There are a whole lot of Titan and Doine images on the photojournal now.

Lots of new images at cassini site check out the haze layers
http://photojournal.jpl.nasa.gov/jpeg/PIA06160.jpg

From cassini home

http://photojournal.jpl.nasa.gov/jpegMod/PIA06162_modest.jpg

"Five narrow angle frames comprise this view of the `wispy terrain' on the anti-Saturn side of Dione. To the surprise of Cassini imaging scientists, the wispy terrain does not consist of thick ice deposits, but rather the bright ice cliffs created by tectonic fractures. The surface is also clearly very heavily cratered. The image scale is 0.9 kilometers (0.6 miles) per pixel; the phase angle is 34 degrees."

I was expecting the same thing, large deposits of ice, I thought the dark areas around the bright wisps were deposits that had darkened with age, was expecting to see the same thing on Iapetus. Well, there goes that theory.

Thanks, Doug. That really explains a lot. It's unfortunate one has to dig for such basic info. I wonder why the Cassini team didn't use a more efficient naming convention, like the one used by MER.

Now, the only thing I'd like to find is a listing of the filters with the wavelengths and bandpasses of each.

I don't know what caused those fractures, either. But their Horst and Graben geometry indicates they were caused by tensional forces, rather than compressional ones. Something stretched the crust apart to form them.

A simple increase in the internal temperature of Dione could cause them. So could some kind of convection mechanism.

That's just a single frame taken from further out

Doug

http://www.spaceflightnow.com/cassini/041216science.html

No, it is 1270x1200 pixels across. And if you compare the per pixel scale of the image, it is clearly made from the same frames as the midrange multicolor sequence that clips off the edges (compare, for example, http://photojournal.jpl.nasa.gov/jpeg/PIA06162.jpg and http://saturn.jpl.nasa.gov/multimedia/imag...6/N00025936.jpg

side by side. They are from the same range. But there are no frames in the raw image section to finish the mosaic. And the edges are clearly not interpolated.

There are three frames of the mosaic on the raw images page. At least two are missing. Attached are two views of Doine (Cassini and Voyager). It seems the trailing and leading hemispheres are very different. I wonder what we will see with Rhea. We thought of it as a Calisto with a fault or two with Voyager, but given the appearance from a distance of the trailing hemisphere, this could be interesting.

Ted

On second thought, I would like to suggest a shockwave origin for the features.

I noticed that there are two, very large circles on Dione. The smaller of the two is roughly centered on 210 degrees longitude, and the larger circle is roughly centered at 30 degrees in this projection.

http://photojournal.jpl.nasa.gov/jpeg/PIA06150.jpg

Those locations are pretty much 180 degrees apart. I don't claim to understand all of the mechanisms that may be involved, but if a major impact occurs on a spherical body, wouldn't one expect that shock waves would travel symmetrically away from the impact site, and converge on a point located 180 degrees away, and then reflect back?

I can imagine a major impact essentially turning a moon into a ringing bell with seismic waves constructively and destructively interferring, creating all kinds of havoc, but mostly preserving the 180 degree symmetry in the end.

I have observed similar things on a number of the moons in our solar system.

I still favor a convection mechanism. I think it explains boththe dark material (outgassing) and the fracturing centered on one area. I'm not sure I'm seeing these "circles" you are talking about (maybe the one at 210 W, with the rough circular shape surrounded on the east by Padua Linea). One the west, are you talking about one surrounded by Carthage Linea and Palentine Linea?

Regarding the cause of the really impressive rifts on Dione (and Tethys and Rhea): the theory suggested as the favorite at Thursday's AGU press conference was simple expansion as the liquid water-ammonia mantle of the just-formed Dione froze. As one paper I've seen recently on Europa points out: in a situation like that the outer layer of ice is then the first to chill below its point of maximum expansion and so start shrinking again, thus getting stretched over the still-warmer and thus larger underlying ice to form extensional cracks, which don't close completely even after the underlying layers of ice also chill down to the point that they start contracting again as well. The particular patterns of resulting stress cracks might have something to do with the distribution of Saturnian tidal forces, or simply random factors.