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Unmanned Spaceflight.com _ Cassini's ongoing mission and raw images _ Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene

Posted by: elakdawalla Feb 20 2010, 04:29 AM

Holy moly are these back-to-back flybys of Rhea and Helene going to ROCK!!!! Jason's http://ciclops.org/view/6221/Rev127?js=1 has all the details. Wispy terrain high-res mosaic -- close look at putative impact sites of former ring particles -- MIMI attempt to confirm presence of Rhea ring -- Imaging of pretty much all of Helene using Saturnshine to illuminate sub-Saturn hemisphere on approach, sunshine on anti-Saturn hemisphere on departure -- departure shots will be against Saturn as a backdrop -- C/A shots will use skeet shoot technique derived for Encelauds -- etc. etc. --

I can't wait!! Thanks Jason for the preview!!!

Posted by: volcanopele Feb 20 2010, 04:33 AM

The CICLOPS Looking Ahead article for Rev127 (February 22-March 12) is now online, detailing the upcoming targeted flybys of Rhea and the trojan moon, Helene. In the case of Rhea, Cassini will fly within 100 km of the surface in order to confirm the presence of a set of narrow rings at that satellite. Images will be acquired of portions of the trailing hemisphere wispy terrain and the equator.

However, the flyby I am looking forward to the most is that of Helene on March 3 @ 13:41 UTC, with an altitude of 1,817 km. In preparation of this encounter, I have created an animation in Celestia showing the views of Helene from the ISS narrow-angle camera (missing some on the third trigger, since there were 48...and I'm tired):



To give you an idea of what Cassini has seen of Helene before:

Rev094 (November 25, 2008): http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=174939
Rev048 (July 20, 2007): http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=116643
Rev027 (August 17, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=80845
Rev027 (August 17, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=80858
Rev021 (February 25, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=64363

Posted by: jasedm Feb 21 2010, 08:28 AM

I'm loving the ring-plane orbits with all these icy moon/rock encounters - lots more to come in the next few months. Thanks VP for the detail included in the looking ahead articles - always very informative, and appetite-whetting.
I must admit I'm a little surprised that that the the 'skeet-shoot' technique is being employed at Helene, but delighted nonetheless - it'll be very intriguing to see how 'smooth' the moon is at a few tens of metres resolution.

Posted by: TritonAntares Feb 21 2010, 11:23 AM

Hi,

just to http://ciclops.org/view/6221/Rev127?js=1:

QUOTE
Cassini's ISS camera starts its observations for Rev127 the day after apoapse by taking images of Iapetus, 1.53 million kilometers (0.95 million miles) away.
During this distant observation, ISS will observe the southern, sub-Saturn hemisphere of Iapetus.
Over the next four days, ISS will take four more multi-spectral observations of Iapetus,
with the distance to the satellite ranging from 1.55 to 1.92 million kilometers (0.97 to 1.12 million miles) away.

As there won't be any more close encounters of this outer large saturnian satellite, these far imagings are the only opportunities to get some further informations, e.g. the north/south pole and hopefully the region around the 'Snowman'.
Any information of other - probably closer - encounters until 2017 available ?

Thanks & Bye.

Posted by: Floyd Feb 21 2010, 02:15 PM

I think not. A search of the SM-7_all.doc (posted here on UMSF somewhere) did not have the word Iapetus. If I recall correctly, it would have taken too much fuel to get into that orbit. If you go to the Cassini site, click Mission Overview, then Saturn Tour Dates. About 10 lines down on that page is a link http://saturn.jpl.nasa.gov/mission/saturntourdates/saturntourdates2010/ for a more complete list of the planned tour dates in 2010. From there you can get to activities for each remaining year of the mission.

Posted by: belleraphon1 Feb 23 2010, 01:06 AM

Looking forward to this one as well.

If Helene is like Calypso, be great to get high resolution of 'striated' terrain. Plus the Rhea "ring" impactors.

Glorious!!!

Craig

Posted by: tasp Feb 23 2010, 03:38 AM

Do we get some close ups of the intriguing equatorial stains ??

I am greatly interested in the 'stuff' orbiting Rhea too. Is it organized more like the asteroid belt (variety of inclinations and eccentricities), or more like the Saturnian rings (more planar and circular orbits)? And perhaps we can pin down the periods of the orbiting 'stuff' and see if there is a correlation to the Rhean period about Saturn.

Also, is more material within or outside the Rhean Roche limit . . . .

Posted by: DrShank Feb 25 2010, 06:31 PM

here are some nice perspective views of Rhea, target of the 100km pass next week.
they are based on stereo imaging of these regions acquired back in 2008. The first shows the western half
of the 6 km deep and 370 km wide Tirawa impact basin. The second shows the now
infamous blue equatorial streaks attributed to impact of Rhea's ring on to the surface. The frames
are from two Rhea flyover videos (too large to upload here) now on youtube (www.youtube.com/galsat400).
The Blue Streak movie shows one of these streaks lying across the top of a battered topographic ridge,
a common occurrence for these features consistent with a ring origin. The paper describing these
and the other Saturn ice moon color features has now been submitted for publication!

more details at http://stereomoons.blogspot.com
and http://www.youtube.com/galsat400

 

Posted by: TritonAntares Feb 25 2010, 10:53 PM

So,
about 75 images are http://saturn.jpl.nasa.gov/photos/raw/index.cfm?start=1&storedQ=2201417.

Here a quickout:


Distance: 1470377 km
Date: 2010-02-21

Nice but distant view of the snowman.

Btw., I thought about some unlisted encounters like this one, when Cassini is near apoapse, roughly 2.4 million kilometers away from Saturn.
From time to time the spacecraft gets in the vicinity of this outer large saturnian satellite.
May be one of the members is able to calculate the closest encounters until 2017 ?

Bye.

Posted by: Adam Hurcewicz Feb 26 2010, 12:54 AM

QUOTE (TritonAntares @ Feb 25 2010, 11:53 PM) *
May be one of the members is able to calculate the closest encounters until 2017 ?
Bye.


Try, use JPL HORIZONS Web-Interface to calculate distance Cassini - Iapetus smile.gif
http://ssd.jpl.nasa.gov/horizons.cgi

Posted by: Floyd Feb 26 2010, 01:39 AM

Hi Adam,
Tried your link, but I can't get it to leave earth for an observer point. What am I doing wrong?

Posted by: Adam Hurcewicz Feb 26 2010, 01:47 AM

QUOTE (Floyd @ Feb 26 2010, 02:39 AM) *
Hi Adam,
Tried your link, but I can't get it to leave earth for an observer point. What am I doing wrong?


Try write:
@Iapetus
or
@608


Posted by: Elias Feb 26 2010, 05:40 PM

I am not sure if MIMI data can confirm the disk/rings scenario. What MIMI data may tell us is whether the structures that will be observed during the flyby in electrons and ions, under a much different geometry compared to the two previous flybys, are consistent with that exciting scenario (or not). Consistent observations under much different geometries, may strengthen the initial interpretation, but definitely not prove it.

I think proof can only come from imaging observations (or maybe other, more direct methods than those based primarily on charged particle data).

Posted by: DrShank Feb 26 2010, 06:45 PM

QUOTE (Elias @ Feb 26 2010, 11:40 AM) *
I am not sure if MIMI data can confirm the disk/rings scenario. What MIMI data may tell us is whether the structures that will be observed during the flyby in electrons and ions, under a much different geometry compared to the two previous flybys, are consistent with that exciting scenario (or not). Consistent observations under much different geometries, may strengthen the initial interpretation, but definitely not prove it.

I think proof can only come from imaging observations (or maybe other, more direct methods than those based primarily on charged particle data).



if it cant be seen from orbit, the best case for corraborative proof then comes from the equatorial features i and others have shown above and elsewhere that are very difficult to attribute to anything but debris orbiting Rhea in a very thin and low density disk. but the motivation for the flyby is these "rings" so here's hoping they find something

Posted by: Elias Feb 26 2010, 09:20 PM

QUOTE (DrShank @ Feb 26 2010, 07:45 PM) *
if it cant be seen from orbit, the best case for corraborative proof then comes from the equatorial features i and others have shown above and elsewhere that are very difficult to attribute to anything but debris orbiting Rhea in a very thin and low density disk. but the motivation for the flyby is these "rings" so here's hoping they find something



But the equatorial features may simply indicate that there was a ring sometime in the past, and its collapse has formed them. Is that right? Its not necessary that the ring system/disk still exists (although in the context of the MIMI observations, one may assume that).

Posted by: DrShank Feb 26 2010, 09:34 PM

QUOTE (Elias @ Feb 26 2010, 03:20 PM) *
But the equatorial features may simply indicate that there was a ring sometime in the past, and its collapse has formed them. Is that right? Its not necessary that the ring system/disk still exists (although in the context of the MIMI observations, one may assume that).


yes that is true, we cant determine the date of the equatorial features. they could be very recent or not forming today.
one thing is fairly clear is they are not ancient or they would have been erased by now!
paul

Posted by: ugordan Feb 26 2010, 09:39 PM

QUOTE (DrShank @ Feb 26 2010, 10:34 PM) *
one thing is fairly clear is they are not ancient or they would have been erased by now!

I.e. they wouldn't be as UV-bright as they are.

Posted by: jasedm Feb 27 2010, 05:20 PM

QUOTE (Elias @ Feb 26 2010, 05:40 PM) *
I am not sure if MIMI data can confirm the disk/rings scenario. What MIMI data may tell us is whether the structures that will be observed during the flyby in electrons and ions, under a much different geometry compared to the two previous flybys, are consistent with that exciting scenario (or not). Consistent observations under much different geometries, may strengthen the initial interpretation, but definitely not prove it.

I think proof can only come from imaging observations (or maybe other, more direct methods than those based primarily on charged particle data).



This may be pertinent:

From the latest Cassini significant events report:

"ULO has received an absolute timed real-time command file from the Cosmic Dust Analyzer instrument team. Starting on DOY-061T16:00, the commands will customize the instrument's visibility to bigger particles during the upcoming Rhea flyby on Mar. 2 and the following periapse passage. The command approval meeting for this file is scheduled for Thursday, Feb. 25.'

Posted by: Hungry4info Feb 28 2010, 02:27 PM

Quick, dirty gif of a mutual event with Dione and ... Rhea?
(That guess is based off what I found in Celestia unsure.gif I suspect it's Cassini trajectory is out of date.)

 

Posted by: volcanopele Feb 28 2010, 08:57 PM

QUOTE (Hungry4info @ Feb 28 2010, 07:27 AM) *
a mutual event with Dione and ... Rhea?

From the Rev127 Looking Ahead article: "Also on February 24, Cassini will observe Dione partially occult Enceladus and its south polar plume. During this observation, Dione will be 2.04 million kilometers (1.27 million miles) away from Cassini and Enceladus 2.27 million kilometers (1.41 million miles) away."

Posted by: Elias Mar 2 2010, 02:19 PM

QUOTE (DrShank @ Feb 26 2010, 10:34 PM) *
yes that is true, we cant determine the date of the equatorial features. they could be very recent or not forming today.
one thing is fairly clear is they are not ancient or they would have been erased by now!
paul


Thanks for the clarification. How can such structures be erased in a inactive moon? Charged particles or interplanetary dust impacts for instance? The E-ring dust can only modify the trailing hemisphere, I assume.



Posted by: tasp Mar 2 2010, 04:22 PM

I am not sure if this would be compression artifacts or just maybe a quirk of the pixel geometry due to the differing colors, but some of the ridges and crater rims in the lower portion of the RH image in post 6 seem to have very fine crenelation (for lack of a better word).


Posted by: peter59 Mar 2 2010, 05:14 PM

http://blogs.jpl.nasa.gov/?p=62 with a fantastic movie made by Cassini navigator Brent Buffington that shows each of the activities performed during Rhea flyby.
http://saturn.jpl.nasa.gov/video/videodetails/?videoID=207

Posted by: ugordan Mar 2 2010, 10:04 PM

Enceladus, plume and rings, RGB:


Posted by: volcanopele Mar 3 2010, 09:37 AM

Animation of Helene flyby just uploaded to youtube (may take 30-60 minutes to finish processing, so be patient):

http://www.youtube.com/watch?v=0aVbvAojQlw

Only 4 hours and 4 minutes until Helene closest approach!

Posted by: ugordan Mar 3 2010, 10:20 AM

Rhea images have started coming down:
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214324
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214340
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214348
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214356
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214378

Posted by: Astro0 Mar 3 2010, 01:28 PM

Handstitched mosaic of Rhea. Image sequence N00152147,51,55,59,67,75,83,91 taken on March 02, 2010 and received on Earth March 03, 2010.


Posted by: Ian R Mar 3 2010, 01:32 PM

Here's a global colour view of Rhea (IR-GR-VIO):


Posted by: Sunspot Mar 3 2010, 01:41 PM

QUOTE (ugordan @ Mar 3 2010, 10:20 AM) *
Rhea images have started coming down:
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214324


Is that vertical stripe in your first image some kind of image artefact?

Posted by: ugordan Mar 3 2010, 01:54 PM

No, it's a real crack.

Posted by: Hungry4info Mar 3 2010, 02:50 PM

Really neat images!

Posted by: Exploitcorporations Mar 3 2010, 08:09 PM

First Helene images arriving:

http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214390

Posted by: Sunspot Mar 3 2010, 08:20 PM

Looks like the pointing is off sad.gif

Posted by: Bjorn Jonsson Mar 3 2010, 08:21 PM

Well, Helene's surface certainly appears smooth as expected:

http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214400

It will be interesting to see the closeups...

Posted by: ugordan Mar 3 2010, 08:27 PM

QUOTE (Sunspot @ Mar 3 2010, 09:20 PM) *
Looks like the pointing is off sad.gif

Yes, but... we got a better shot of Saturn's cloudtops in return!

http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214425

Posted by: Ian R Mar 3 2010, 08:29 PM

Helene in Saturn-shine:


Posted by: volcanopele Mar 3 2010, 08:36 PM

QUOTE (Sunspot @ Mar 3 2010, 01:20 PM) *
Looks like the pointing is off sad.gif

Yes, it is a bit disappointing, but have no fear! We get another flyby of this gal next year!

Posted by: Ian R Mar 3 2010, 08:43 PM

I guess this will be the highest resolution view of Helene for a while, then...

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS58/N00152244.jpg

Posted by: volcanopele Mar 3 2010, 08:56 PM

Nope this beats it:

http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=214417

Posted by: Exploitcorporations Mar 3 2010, 09:06 PM

I imagine that some careful compositing, a la Tempel 1, might make for some beautiful mosaics with patches of high resolution. The varied perpectives of the lower-resolution global frames are very nice too.

Posted by: ugordan Mar 3 2010, 09:07 PM

Looks to me there's too much rotation to pull off a Deep Impact impactor-camera-type mosaic.

Posted by: Phil Stooke Mar 3 2010, 09:11 PM

Cripes - now we've got gullies on Helene...

Phil

Posted by: volcanopele Mar 3 2010, 09:53 PM

Phil, that sent a chuckle among the HiRISE people here laugh.gif

Posted by: jasedm Mar 3 2010, 10:06 PM

It just shows the standard we've come to expect from this mission that we're a tad disappointed with the images at closest approach. I'm sure the pointing commands for the follow-up flyby will be tweaked based on the results from this one, with even more spectacular results. Kudos to the Cassini team for the double-header flyby.

Incidentally, I wonder how difficult in comparison it will be to image Methone in a couple of years time. The flyby is a similar range, but Cassini will be travelling faster, and Methone is a tenth the size of Helene....

Posted by: ngunn Mar 3 2010, 10:17 PM

Have we had all the Rhea images now, and if so has anybody found signs of the possibly ring related equatorial marks?

Posted by: volcanopele Mar 3 2010, 10:19 PM

Well, the issue might have been not so much the pointing, but our understanding of the position of Helene... mean, we were pointed where we planned it, but Helene was not where we expected it to be. High resolution images such as these presumably will also be used to help refine our knowledge of the orbit of Helene.

Posted by: jasedm Mar 3 2010, 10:21 PM

One of the better global raws, rotated so the large crater is at the top, and with a bit of shadow/highlight enhancement:


 

Posted by: AndyG Mar 3 2010, 10:23 PM

QUOTE (volcanopele @ Mar 3 2010, 10:19 PM) *
...we were pointed where we planned it, but Helene was not where we expected it to be.


When was Newton taken off the wheel? rolleyes.gif

(Just kidding)

Andy

Posted by: volcanopele Mar 3 2010, 10:39 PM

QUOTE (jasedm @ Mar 3 2010, 03:21 PM) *
One of the better global raws, rotated so the large crater is at the top, and with a bit of shadow/highlight enhancement:

North is to the lower right in your image there.

Posted by: jasedm Mar 3 2010, 10:45 PM

Ah yes, you're right, I overlooked the rim of that (relatively) huge crater.

Posted by: ngunn Mar 3 2010, 10:52 PM

QUOTE (AndyG @ Mar 3 2010, 10:23 PM) *
When was Newton taken off the wheel?


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

Posted by: NickF Mar 3 2010, 10:54 PM

QUOTE (volcanopele @ Mar 3 2010, 10:19 PM) *
Well, the issue might have been not so much the pointing, but our understanding of the position of Helene... mean, we were pointed where we planned it, but Helene was not where we expected it to be.


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

Posted by: machi Mar 4 2010, 10:57 AM

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

 

Posted by: stevesliva Mar 4 2010, 05:25 PM

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.

Posted by: Frank Crary Mar 4 2010, 07:52 PM

QUOTE (ngunn @ Mar 3 2010, 10:52 PM) *
QUOTE (AndyG @ Mar 3 2010, 10:23 PM) *
When was Newton taken off the wheel?

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


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.

Posted by: ngunn Mar 4 2010, 09:59 PM

Welcome to UMSF Frank.

Posted by: Ian R Mar 5 2010, 01:53 AM

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:


Posted by: machi Mar 7 2010, 03:58 PM

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).

 

Posted by: machi Mar 7 2010, 04:28 PM

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


 

Posted by: alan Mar 7 2010, 04:51 PM

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?

Posted by: Ian R Mar 8 2010, 01:42 AM

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


Posted by: Ian R Mar 11 2010, 01:05 AM

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



PNG Version:

http://img36.imageshack.us/i/heleneminiatlaspng.png/

Posted by: elakdawalla Mar 11 2010, 02:08 AM

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?

Posted by: machi Mar 11 2010, 10:26 AM

I always love images of this kind!

Posted by: Ian R Mar 11 2010, 11:36 AM

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/rawimagedetails/index.cfm?imageID=174939
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=175050

Ian.

Posted by: tasp Mar 11 2010, 02:37 PM

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.




Posted by: jasedm Mar 11 2010, 08:46 PM

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

Posted by: belleraphon1 Mar 15 2010, 10:11 PM


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

Posted by: Antdoghalo Mar 16 2010, 01:56 AM

QUOTE (belleraphon1 @ Mar 15 2010, 06:11 PM) *
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?! blink.gif

Posted by: nprev Mar 16 2010, 02:00 AM

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.

Posted by: Juramike Mar 16 2010, 02:50 AM

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

Posted by: ugordan Mar 16 2010, 09:11 AM

QUOTE (belleraphon1 @ Mar 15 2010, 11:11 PM) *
Some of the magnetospheric and plasma science instruments teams reported that they’re seeing some really interesting and surprising results!

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

Posted by: tasp Mar 16 2010, 01:54 PM

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



Posted by: Ian R Sep 23 2010, 11:49 AM

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:



Posted by: Ian R Sep 30 2010, 02:42 PM

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

Posted by: Phil Stooke Sep 30 2010, 07:27 PM

Very nice - thanks!

Phil

Posted by: Hungry4info Nov 26 2010, 03:04 AM

An oxygen-carbon dioxide atmosphere has been observed at Rhea.
http://news.nationalgeographic.com/news/2010/11/101125-saturn-moon-oxygen-atmosphere-discovered-science-space

And a rather shocking interpretation of this,
http://io9.com/5699149/saturns-moon-rhea-may-have-a-breathable-atmosphere

Posted by: nprev Nov 26 2010, 03:28 AM

mad.gif

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.

Posted by: belleraphon1 Nov 26 2010, 12:03 PM


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

Craig

Posted by: centsworth_II Nov 26 2010, 01:17 PM

QUOTE (nprev @ Nov 25 2010, 10:28 PM) *
At least the comments are (mostly) quite properly skeptical; nobody's buying it....

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

Posted by: nprev Nov 26 2010, 06:02 PM

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

Posted by: Hungry4info Nov 27 2010, 05:11 PM

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.

 

Posted by: Elias Nov 29 2010, 10:36 PM

QUOTE (Hungry4info @ Nov 27 2010, 07:11 PM) *
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.

Posted by: Paolo Dec 23 2010, 08:04 PM

the discovery of Rhea's "atmosphere" is now on Science: http://www.sciencemag.org/content/330/6012/1813.abstract

Posted by: Juramike Jun 1 2011, 03:46 AM

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



(Processing details on http://www.flickr.com/photos/31678681@N07/5784294693/in/photostream)

Posted by: nprev Jun 1 2011, 03:59 AM

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

Posted by: AndyG Jun 1 2011, 10:52 AM

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

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