Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene, Also distant Iapetus |
Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene, Also distant Iapetus |
Feb 26 2010, 09:34 PM
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#16
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Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, texas Member No.: 1828 |
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 -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
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Feb 26 2010, 09:39 PM
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#17
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
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. -------------------- |
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Feb 27 2010, 05:20 PM
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#18
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
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.' |
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Feb 28 2010, 02:27 PM
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#19
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Senior Member Group: Members Posts: 1413 Joined: 26-July 08 Member No.: 4270 |
Quick, dirty gif of a mutual event with Dione and ... Rhea?
(That guess is based off what I found in Celestia I suspect it's Cassini trajectory is out of date.) -------------------- -- Hungry4info (Sirius_Alpha)
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Feb 28 2010, 08:57 PM
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#20
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Senior Member Group: Moderator Posts: 3225 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
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." -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Mar 2 2010, 02:19 PM
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#21
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Junior Member Group: Members Posts: 30 Joined: 30-May 05 Member No.: 396 |
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. |
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Mar 2 2010, 04:22 PM
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#22
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
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).
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Mar 2 2010, 05:14 PM
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#23
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
Interesting JPL blog 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 -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Mar 2 2010, 10:04 PM
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#24
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
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Mar 3 2010, 09:37 AM
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#25
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Senior Member Group: Moderator Posts: 3225 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
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! -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Mar 3 2010, 10:20 AM
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#26
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
Rhea images have started coming down:
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214324 http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214340 http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214348 http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214356 http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214378 -------------------- |
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Mar 3 2010, 01:28 PM
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#27
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Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
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Mar 3 2010, 01:32 PM
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#28
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Lord Of The Uranian Rings Group: Members Posts: 798 Joined: 18-July 05 From: Plymouth, UK Member No.: 437 |
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Guest_Sunspot_* |
Mar 3 2010, 01:41 PM
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#29
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Guests |
Rhea images have started coming down: http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=214324 Is that vertical stripe in your first image some kind of image artefact? |
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Mar 3 2010, 01:54 PM
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#30
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
No, it's a real crack.
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