He was no good. As soon as there were more than two bodies his calculations went to pieces.

Better this way than Cassini ending up as bugsplat on Helene's windshield

Darkside of Helene.
Combination from five raw images.
Approximately 2× magnified.

Nice machi! You brought out some gullies/streaks in the lower left there.

They all remind me of that closeup of the crater in Stickney on Phobos.

Actually, that's another reason the Helene images very interesting. Helene is a trojan moon of Dione. It turns out the three-body interaction makes Helene's orbit a sensitive measure of the Dione:Saturn mass ratio. I suspect someone can turn an off-center image of Helene into an improved determination of Dione's mass.

Welcome to UMSF Frank.

In this montage, the two views to the right are wide-angle shots of Helene which I presume were taken during the unsuccessful skeet-shoot sequence, while the left-most view is a NAC frame taken as Cassini was receding from the moon with Saturn providing a backdrop:

Click to view attachment

Nice montage Ian R!

I send another two views of Helene.
First image is higher resolution combination of the darkside (from 4 images).
Second is highest resolution image of Helene (global image is WAC frame). Resolution of this image is aproximately 20 meters per pixel (my rough estimate).

And third image.
It's a combination from 13 images.

Lots of linear features on the crater rim, the results of landslides I assume. If a landslide was occurring while you were observing Helene, at ~0.001g, could you tell it was happening?

Very nice work indeed, Machi. Here's my attempt to link together all of the medium-resolution views of this moon, using some of its more prominent surface features:

Click to view attachment

Here's another attempt of making sense of the many different views of this little moon:

Click to view attachment

PNG Version:

This is really awesome. One thing that I think would add to it is if you could trace in different colors the longitude lines on the simulated views that mark 0 (sub-Saturn), 90, 180 (anti-Saturn), and 270. That's something I wish the rings node viewer did automatically, but it doesn't. It'd really help me orient myself. What do you think?

I always love images of this kind!

Glad you got a kick out of my little experiment Emily; I went ahead and added the coloured meridians to the simulated views as per your suggestion (see my original post).

I enjoyed your latest blog entry elucidating the possible reasons why the skeet-shoot encounter didn't entirely go to plan. For the UMSF folks who haven't seen or read it yet, you can find the article here:

http://www.planetary.org/blog/article/00002383/

Interestingly, this isn't the first time that a non-targeted flyby of Helene has produced some poorly-framed views; the of images taken in November 2008 show the moon right at the edge of the frame, slowly moving out of sight as the sequence progresses:

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=174939
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=175050

Ian.

Fascinating how Helene can probe the mass ratio of Dione to Saturn for us.

At first glance, one might think whatever the initial trajectory of Helene was as it morphed into the Trojan relationship (assuming it did not form there) would swamp any subtle effects like the mass ratio effect. I concede I tend to think of these Trojan objects in a 2 dimensional realm as they 'wobble' about the actual Trojan point, where as in reality, objects like Helene would be exhibiting 'wobbles' in inclination too, making for three dimensional excursions in it's 'average' alignment with Dione and Saturn.

Taking this a step further, that initial orbit of Helene prior to dropping into the Trojan relationship (again, assuming it had one) would be even harder to discern now.

Just wanted to add to the chorus of approval of your montage Ian - stirling stuff!

Rhea encounter...

" At a science meeting Friday (03/05/10?), we talked about a few of the preliminary results. Some of the magnetospheric and plasma science instruments teams reported that they’re seeing some really interesting and surprising results! So stay tuned to hear more about those!"
Amanda Hendrix

http://blogs.jpl.nasa.gov/?p=64

Craig

I cant wait to find out what they found!
Did they find more evidence of rings?!
Or did they find a volcanic plume?!

It sounds interesting all right, but don't get too excited yet.

Saturn's immediate neighborhood is a very dynamic place, and without knowing the specifics there are a great many less spectacular possible explanations for unusual magnetic/plasma observations. Let's wait & see.

I think Rhea has been underappreciated. I'm looking forward to hearing more!

Ahh, so the Monolith is there! I wondered where that thing went...

Evidently, Cassini did not impact anything too big near Rhea . . . .

I notice that the best narrow-angle shot of Helene from the March flyby has been released:

http://photojournal.jpl.nasa.gov/catalog/PIA12723

I've rotated the TIFF, so that north is up, and generated an enhanced version that highlights the small-scale surface features:

Click to view attachment

Of minor interest, I'm sure, is a video of the Helene flyby I put together ages ago, quickly forgot about and then rediscovered only recently:

http://www.youtube.com/watch?v=SP1fnh4vsKQ&fmt=43

Very nice - thanks!

Phil

An oxygen-carbon dioxide atmosphere has been observed at Rhea.
National Geographic link

And a rather shocking interpretation of this,
Saturn's moon Rhea may have a breathable atmosphere

At least the comments are (mostly) quite properly skeptical; nobody's buying it.

This site's audience seems far more informed than the author of that piece of tripe.

EDIT: Just sent a blistering e-mail to the editor-in-chief of that site; let's see if it does any good.

Deep breathes, nprev, deep breathes...... just don't do that on the surface of Rhea.

Craig

I noticed that too. I liked this one: "And now I would like to submit my application for io9 science editor... "

Grr. (I'm cool, Craig, I'm cool!) Article's still up as of 26 Nov/1743 GMT, no retractions, no corrections.

Must be a US site, nobody's watching the store during the (informal) holiday here. No reply to my e-mail from last night, either.

I will maintain robotic vigilance (that's the best kind, of course) over this issue

Dropping the S/N for a sec for an artistic interpretation of the latest news.

I'm curious what the presence of the atmosphere means for those strange readings that was originally interpreted as a ring.

Not much... This exosphere is not that dense to either absorb high-energy electrons or to drive a strong interaction with the flowing plasma, like we see at Io, Europa, Enceladus etc.

the discovery of Rhea's "atmosphere" is now on Science: Cassini Finds an Oxygen–Carbon Dioxide Atmosphere at Saturn’s Icy Moon Rhea

Image of Helene from March 3, 2010 flyby using "super-resolution" technique and PDS images:

Click to view attachment

(Processing details on flickr)

That's an "oooo!!!" That's an "ahhhhh!" Like WOW, Mike!

And I can't help but add "groovy".