Cassini's second hyperclose pass of Dione is just days away. Ive posted some new views and thoughts about Dione
on FB and YT (links below) of some of the features that might be visible in the images, which will show mostly the leading
hemisphere. Jeff Moore and I have been working on a volcanic hypothesis for the smooth plains and the odd features found within
it, which we hope to submit for publication very soon.


images-
http://www.facebook.com/paul.schenk?ref=profile
http://stereomoons.blogspot.com/
movie -
http://www.youtube.com/user/galsat400

I can't use FB and You Tube at work......

We'll you'll either have to quit your job or just wait till you get home to look at that stuff then!

Thanks for the links, Paul. Looking forward to the flyby!

Images from the Dione flyby are starting to show up even though some of the image links at the Cassini website are broken. Some semi-random examples:

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215456
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215471
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215449

Interesting fractures and linear features - I doubt the horizontal lines are real but don't have time for detailed inspection of the images now:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215441

More bright fractures:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215427

This is surely not Saturn as the image caption states:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215391

And not this one either:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215388

The Dione images labeled "Saturn" are taken during closest approach, from a range of a few 100 km- the spacecraft was in a fixed attitude to measure particles and fields, but we were able to arrange it so the fields of view of the cameras and other remote sensing instruments were dragged across the disk of Dione during the passage. That explains why some of the NACs are blurred- the spacecraft was not tracking Dione, and we were very close.

John

Good grief...

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215529

Yikes, I hope it doesn't fall off...

Some nice pics of Janus and Epimetheus on this periapsis too.

Phil

Oh boy...

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=215391

Yes, Bjorn pointed that out.

Is it an icy cliff? Or the wall of a crater?

Reminds me of this.

"Is it an icy cliff? Or the wall of a crater? "

Both. If you turn it upside down it's easier to interpret. It's an oblique view across fractured terrain and a crater.

Phil

"The camera was pointing toward SATURN...."
Click to view attachment

Oh wow..... wow.... wow....

...yeah, what Lyford said!

This one's really giving me a 'what the hell?!' feeling like the early encounters of other moons. I don't even wanna speculate about what exactly we're looking at; need context.

Ahhh.... that did help.

That's a little better. There are still some very puzzling small-scale features, though, and it does give the impression of relative youth to me.

This is a common problem with images that come through Canberra, they wind up upside down. Here it is rotated 180.

Bonzer! (hey, where's my Barry McKenzie dictionary?)

Phil

Cool!

Bright short wavy fractures, bright icy-cliffed craters and long straight lineaments.
This recent image of Dione: http://saturn.jpl.nasa.gov/multimedia/imag...9/W00063496.jpg

Looks real similar to features on Rhea:
fractures/bright crater on Rhea: http://www.flickr.com/photos/31678681@N07/...57622089931268/
long lineaments on Rhea: http://www.flickr.com/photos/31678681@N07/...57622089931268/

Note how the lineament on Dione cuts right through the crater, but seems offset. Perspective due to depth?

Maybe it prexisted before the crater formed?

that is starting to look like what i am getting in blender
N1481738274_4.img
Click to view attachment

or should i say I am getting close to Cassini

EGD: This is a common problem with images that come through Canberra, they wind up upside down.

Nah, we get 'em the right way up, we just turn them upsidedown to confuse you northeners

Had to play with this lovely view of Dione.
A blending of images W00063488 and W00063489 with a touch of colour for effect.
Click to view attachment

That's a keeper, Astro0!

The oblique view of the tectonic cliffs has to be one of the classic images from this mission. Absolutely jaw-dropping, and a human-scale landscape to boot. I expect to see this one widely published for years to come.

Note that there is context for most or all of the highest-res NAC images taken during the "ORS Drag" at closest approach (the ones labeled "Saturn") - there are simultaneous WACs, though they are not next to each other on the raw image pages so you have to look around to match them up.

John

Here's context for that NAC shot:

Click to view attachment

Wow--that does help. Thanks John and Gordan.

Another pair, also rotated 180 deg, to make illumination come from "above":

Click to view attachment

That looks like a much higher resolution shot than above.

Wow, look at the very narrow fractures in the highest resolution shot. They would be completely unexpected based on the other image alone, even though that looks like it's "very high resolution" itself. Now we need a context image for the first one!

Phil

The scale on that NAC image is about 6 meters/pixel, though smear and noise make the resolution worse than that. So the fracture is really tiny- something like 50 meters wide.

John

It's fractures all the way down to the resolution limit, baby!

Belated thanks as well, John & Gordan!

Interesting observation as well, Gordan: "...fractures all the way down to the resolution limit..." Hmm.

Occurs to me that such widespread fracturing could vastly increase the total amount of Dione's surface area to space & radiation. Could sputtering alone explain Dione's apparent low-level outgassing?

Radiationwise, the surface area of a given body is always the same: the area subtended by the body from the perspective of an observer at a distance of infinity in the direction the radiation is coming from. That is, there is no possible path of an incoming ray that would hit the surface of a highly-fractured Dione but not a smooth Dione. The same argument applies to cratering. However, that doesn't mean there aren't other reasons why a high surface area could increase outgassing - but it's unlikely that such a property could actually cause outgassing that would not otherwise occur at all.

And if Dione is reflective?

Same response.

Even if Dione is reflective, only the surface in our line of sight can reflect particles toward us.

April, 20 view (N00153311/12/13-RGB filters-motion compensated):
Click to view attachment