Apr 6 2010, 04:38 PM
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.
movie - http://www.youtube.com/user/galsat400
Apr 6 2010, 04:49 PM
I can't use FB and You Tube at work......
Apr 6 2010, 05:33 PM
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!
Apr 8 2010, 03:57 PM
Apr 8 2010, 04:22 PM
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.
Apr 8 2010, 05:33 PM
Yikes, I hope it doesn't fall off...
Some nice pics of Janus and Epimetheus on this periapsis too.
Apr 8 2010, 05:50 PM
Yes, Bjorn pointed that out.
Is it an icy cliff? Or the wall of a crater?
Apr 8 2010, 05:54 PM
QUOTE (Phil Stooke @ Apr 8 2010, 07:33 PM)
Yikes, I hope it doesn't fall off...
Reminds me of this
Apr 8 2010, 06:29 PM
"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.
Apr 8 2010, 06:41 PM
"The camera was pointing toward SATURN...." Click to view attachment
Apr 9 2010, 12:26 AM
Oh wow..... wow.... wow....
Apr 9 2010, 12:45 AM
...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.
Apr 9 2010, 01:53 AM
QUOTE (Phil Stooke @ Apr 8 2010, 12:29 PM)
If you turn it upside down...
Ahhh.... that did help.
Apr 9 2010, 02:23 AM
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.
Apr 9 2010, 03:19 AM
QUOTE (Phil Stooke @ Apr 8 2010, 10:29 AM)
If you turn it upside down it's easier to interpret. ....
This is a common problem with images that come through Canberra, they wind up upside down. Here it is rotated 180.
Apr 9 2010, 03:35 AM
Bonzer! (hey, where's my Barry McKenzie dictionary?)
Apr 9 2010, 03:48 AM
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?
Apr 10 2010, 06:47 AM
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
Apr 10 2010, 07:02 AM
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
Apr 10 2010, 08:49 AM
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.
Apr 10 2010, 02:36 PM
QUOTE (nprev @ Apr 9 2010, 12:45 AM)
I don't even wanna speculate about what exactly we're looking at; need context.
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.
Apr 10 2010, 03:54 PM
Here's context for that NAC shot:Click to view attachment
Apr 10 2010, 04:22 PM
Wow--that does help. Thanks John and Gordan.
Apr 10 2010, 04:25 PM
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.
Apr 10 2010, 06:06 PM
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!
Apr 10 2010, 06:36 PM
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.
Apr 10 2010, 06:40 PM
It's fractures all the way down to the resolution limit, baby!
Apr 12 2010, 01:16 AM
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?
Apr 12 2010, 01:35 AM
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.
Apr 12 2010, 02:34 AM
QUOTE (jekbradbury @ Apr 11 2010, 09:35 PM)
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.
And if Dione is reflective?
Apr 13 2010, 04:41 PM
Even if Dione is reflective, only the surface in our line of sight can reflect particles toward us.
Apr 28 2010, 05:03 AM
April, 20 view (N00153311/12/13-RGB filters-motion compensated):Click to view attachment
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