On a ring origin of the equatorial ridge of Iapetus |
Unmanned Spaceflight.com > Outer Solar System > Saturn > Cassini Huygens > Cassini's ongoing mission and raw imagesOn a ring origin of the equatorial ridge of Iapetus |
| Guest_AlexBlackwell_* |
 Aug 29 2006, 06:18 PM
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Wing Ip just had an interesting Iapetus-related paper published in GRL.
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Sep 8 2006, 05:54 PM
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 Director of Galilean Photography  Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
I still don't see how the two divergent ridges get created by a decaying ring. The orbital speed of the ring at low altitude would not be the same as the rotational velocity of a proto-Iapetus. So, how do the angled ridges get created?? If the ring was at an angle to Iapetus, as it descended it would not stay above a single location.
I favor a tectonic explaination. We have symmetrical ridges here on Earth due to seafloor spreading. Seems like a reasonable explaination to me. The question would be why would there be a single crack along a great circle? Maybe Iapetus had a Europa-like episode with a shallow ocean, and as it slowly froze it expanded/contracted enough to crack open. Without nearby moons and tides, the crack went around the planet symmetrically. -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Sep 8 2006, 08:29 PM
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 Member Group: Members Posts: 288 Joined: 28-September 05 From: Orion arm Member No.: 516 |
QUOTE 37th DPS Meeting, 4-9 September 2005 Session 47 Icy Satellites [47.08] The topography of Iapetus' leading side B. Giese (DLR-Institute of Planetary Research, Berlin, Germany), T. Denk, G. Neukum (Institut fur Geologische Wissenschaften, Freie Univ. Berlin, Germany), C. C. Porco (Cassini Imaging Central Laboratory for Operations, Space Science Institute, Boulder, CO, USA), T. Roatsch, R. Wagner (DLR-Institute of Planetary Research, Berlin, Germany) We have used Cassini-stereo images to derive a topographic model of Iapetus' leading side. The model reveals that Iapetus has substantial topography with heights (referenced to a 747 x 744 x 713 km ellipsoid (Thomas et al., in preparation)) in the range of -9 km to +15 km... Hhm, this strange ellipsoid figure could be a hint for some internal force once having driven a probable tectonic mechanism and causing the ridge... 
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Sep 9 2006, 05:28 AM
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 Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
QUOTE (TritonAntares @ Sep 8 2006, 03:29 PM)  Hhm, this strange ellipsoid figure could be a hint for some internal force once having driven a probable tectonic mechanism and causing the ridge... Due to Iapetus large distance from Saturn, it's low orbital speed would have caused Iapetus to be the slowest formed satellite of the major Saturnian moons. This would allow longer time for impact heat to radiate away during accretion, and the accreted materials would be more depleted of Al26 (or is it 27? I forget) and subsequent radiogenic heating of Iapetus would be lower. Also, due to the great distance to Saturn, tidal heating of Iapetus would be uniquely low, Iapetus having been very leisurely braked into tide lock with Saturn. The effect of all this is that Iapetus would have experienced much lower temperatures, and have been far more rigid crustally to preserve the 'congenital lumpiness' of its' later stages of accretion. |
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AlexBlackwell On a ring origin of the equatorial ridge of Iapetus Aug 29 2006, 06:18 PM
volcanopele okay, now a ring around Iaptetus is an interesting... Aug 29 2006, 06:20 PM AlexBlackwell Here's an interesting passage from the conclud... Aug 29 2006, 06:25 PM Michael Capobianco Does the paper address why the equatorial ridge do... Aug 29 2006, 06:40 PM
David QUOTE (Michael Capobianco @ Aug 29 2006, 06... Aug 29 2006, 07:05 PM
Decepticon QUOTE (Michael Capobianco @ Aug 29 2006, 02... Aug 29 2006, 11:56 PM JRehling Roughly speaking, I guess the fact that the ridge ... Aug 30 2006, 01:07 AM jsheff Would this process also explain the albedo assymet... Aug 29 2006, 07:06 PM tasp QUOTE (jsheff @ Aug 29 2006, 02:06 PM) Wo... Sep 10 2006, 01:35 AM AlexBlackwell QUOTE (Michael Capobianco @ Aug 29 2006, 08... Aug 29 2006, 07:44 PM tasp An object skimming the surface of Iapetus will hav... Aug 30 2006, 05:11 AM AlexBlackwell There was a brief blurb about this paper yesterday... Aug 30 2006, 07:53 PM Rob Pinnegar I guess this idea probably originated with those i... Aug 30 2006, 09:41 PM tasp QUOTE (Rob Pinnegar @ Aug 30 2006, 04:41 ... Aug 30 2006, 11:29 PM dvandorn Does Iapetus' ridge have to have been created ... Aug 31 2006, 12:04 AM tasp Maintaining focus (or collimation) of the strand ... Aug 31 2006, 03:02 AM David I think I understand the idea to be one of a low-v... Aug 31 2006, 07:23 AM ngunn Under the scenario proposed I would expect volatil... Aug 31 2006, 10:00 AM ugordan QUOTE (ngunn @ Aug 31 2006, 11:00 AM) Cou... Aug 31 2006, 11:18 AM ngunn QUOTE (ugordan @ Aug 31 2006, 12:18 PM) M... Aug 31 2006, 11:50 AM ugordan The point I was trying to make is the greatest tem... Aug 31 2006, 12:08 PM ngunn QUOTE (ugordan @ Aug 31 2006, 01:08 PM) A... Aug 31 2006, 12:38 PM ngunn One other point - the 'catastrophic atmosphere... Aug 31 2006, 01:06 PM tasp Invoking an atmosphere above a certain very low de... Aug 31 2006, 01:27 PM ngunn QUOTE (tasp @ Aug 31 2006, 02:27 PM) Invo... Aug 31 2006, 02:01 PM The Messenger QUOTE (tasp @ Aug 31 2006, 07:27 AM) I al... Sep 3 2006, 11:22 PM ngunn QUOTE (The Messenger @ Sep 4 2006, 12:22 ... Sep 4 2006, 10:13 AM The Messenger QUOTE (ngunn @ Sep 4 2006, 04:13 AM) Why?... Sep 6 2006, 03:21 AM ngunn QUOTE (The Messenger @ Sep 6 2006, 04:21 ... Sep 6 2006, 08:15 AM JRehling A comment on followup missions: Whatever future mi... Sep 6 2006, 12:02 PM ugordan QUOTE (JRehling @ Sep 6 2006, 01:02 PM) A... Sep 6 2006, 12:29 PM mchan QUOTE (ugordan @ Sep 6 2006, 05:29 AM) Tr... Sep 6 2006, 11:15 PM ugordan QUOTE (mchan @ Sep 7 2006, 12:15 AM) I do... Sep 7 2006, 06:58 AM TritonAntares Hi,
let us anticipate the equatorial ridge was bui... Sep 6 2006, 08:51 AM ugordan The ridge is ancient which means the ring is also ... Sep 6 2006, 09:03 AM ngunn QUOTE (ugordan @ Sep 6 2006, 10:03 AM) Pe... Sep 6 2006, 12:41 PM ngunn QUOTE (TritonAntares @ Sep 6 2006, 09:51 ... Sep 6 2006, 09:05 AM tasp QUOTE (TritonAntares @ Sep 6 2006, 03:51 ... Sep 9 2006, 02:32 PM JRehling QUOTE (The Messenger @ Sep 3 2006, 04:22 ... Sep 5 2006, 04:44 PM tasp And this, consider the oblique impactor that may h... Aug 31 2006, 01:33 PM ngunn Note the following sentence already quoted by Alex... Aug 31 2006, 02:52 PM tasp I am having trouble seeing how the precipitating l... Aug 31 2006, 03:56 PM Rob Pinnegar You mention "attendant ridges". This was... Aug 31 2006, 05:20 PM ngunn On multiple ridges - perhaps the emplacement of th... Sep 1 2006, 11:26 AM tasp I admit a certain favoring of an oblique impact kn... Sep 1 2006, 01:45 PM ngunn This discussion has become really interesting. I... Sep 1 2006, 02:52 PM ngunn Just found John Rehling's rather nice diagram ... Sep 4 2006, 01:49 PM TritonAntares Hi,
I've just been back from a 1-week-vacation... Sep 5 2006, 10:27 AM ngunn I did ask the other day for someone to re-post an ... Sep 6 2006, 02:08 PM ugordan QUOTE (ngunn @ Sep 6 2006, 03:08 PM) I di... Sep 6 2006, 02:15 PM djellison Links to that place are not a good idea. Can peop... Sep 6 2006, 02:13 PM ngunn QUOTE (djellison @ Sep 6 2006, 03:13 PM) ... Sep 6 2006, 02:31 PM Themisto QUOTE (ngunn @ Sep 6 2006, 04:31 PM) Sorr... Sep 6 2006, 03:06 PM djellison That's better
We used to worry about mention... Sep 6 2006, 03:10 PM ngunn OK let's see if this works..
http://www.aaw-d... Sep 6 2006, 03:45 PM tasp 3 intersecting ridges, all describing segments of ... Sep 6 2006, 06:47 PM ngunn QUOTE (tasp @ Sep 6 2006, 07:47 PM) The f... Sep 7 2006, 08:51 AM tasp Some of the criteria that seem to be needed for us... Sep 7 2006, 02:58 PM ngunn QUOTE (tasp @ Sep 7 2006, 03:58 PM) Some ... Sep 7 2006, 03:45 PM tasp We may find Iapetan like ridge structures on a per... Sep 7 2006, 03:03 PM TritonAntares Hi,
before we should keep on speculating whether t... Sep 7 2006, 03:50 PM ngunn QUOTE (TritonAntares @ Sep 7 2006, 04:50 ... Sep 8 2006, 10:44 AM ugordan I have absolutely no idea on which internal proces... Sep 8 2006, 11:05 AM ngunn QUOTE (ugordan @ Sep 8 2006, 12:05 PM) I ... Sep 8 2006, 12:04 PM ugordan QUOTE (ngunn @ Sep 8 2006, 01:04 PM) On g... Sep 8 2006, 12:25 PM ngunn QUOTE (ugordan @ Sep 8 2006, 01:25 PM) It... Sep 8 2006, 12:45 PM ugordan Yeah, but why would it flatten itself along the eq... Sep 8 2006, 12:50 PM Rob Pinnegar Two things today:
QUOTE (ugordan @ Sep 8 200... Sep 8 2006, 01:56 PM ynyralmaen QUOTE (ngunn @ Sep 8 2006, 12:44 PM) So, ... Sep 8 2006, 11:34 AM ngunn QUOTE (ynyralmaen @ Sep 8 2006, 12:34 PM)... Sep 8 2006, 12:12 PM tasp QUOTE (ngunn @ Sep 8 2006, 05:44 AM) So, ... Sep 8 2006, 01:33 PM Bill Harris This has been a fascinating discussion. Before Ca... Sep 8 2006, 12:56 PM ngunn Hello Bill - nice to know it's not just the 4 ... Sep 8 2006, 01:18 PM tasp QUOTE (ngunn @ Sep 8 2006, 08:18 AM) Hell... Sep 8 2006, 01:40 PM tasp Some where here at UMSF is a nice map of Iapetus (... Sep 8 2006, 02:27 PM tasp I will note that Iapetus is subject to the smalles... Sep 8 2006, 02:30 PM ugordan However, the surface gravity at Iapetus is also va... Sep 8 2006, 02:38 PM tasp I also point out that the New Solar System books... Sep 8 2006, 02:36 PM tasp Virtually all solar system objects are believed to... Sep 8 2006, 02:52 PM ngunn Is this the one? http://photojournal.jpl.nasa.gov/... Sep 8 2006, 02:54 PM tasp QUOTE (ngunn @ Sep 8 2006, 09:54 AM) Is t... Sep 8 2006, 02:59 PM ugordan Iapetus is undeniably oblate, but the question is ... Sep 8 2006, 03:04 PM tasp QUOTE (ugordan @ Sep 8 2006, 10:04 AM) Ia... Sep 9 2006, 05:31 AM ngunn QUOTE (TritonAntares @ Sep 8 2006, 09:29 ... Sep 9 2006, 08:59 AM tasp QUOTE (ngunn @ Sep 9 2006, 03:59 AM) . . ... Sep 9 2006, 01:56 PM ngunn QUOTE (tasp @ Sep 9 2006, 02:56 PM) I hav... Sep 9 2006, 09:56 PM tasp QUOTE (hendric @ Sep 8 2006, 12:54 PM) I ... Sep 9 2006, 05:10 AM tasp Also, check out the big elongated crater at 0 to 3... Sep 9 2006, 05:35 AM tasp Just noticed I did not address moonlets below sync... Sep 9 2006, 09:00 PM tasp I am thinking we aren't going to see an Iapeta... Sep 10 2006, 01:00 AM tasp Speaking of New Horizons, how far out can it produ... Sep 10 2006, 01:11 AM tasp Regarding perturbations of a possible Iapetan ring... Sep 10 2006, 05:08 PM Michael Capobianco Well, I'm still a bit skeptical as well. For o... Sep 10 2006, 05:18 PM tasp Of course, the most interesting bit of the ridge s... Sep 10 2006, 06:00 PM ngunn So much to reply to (no, it isn't driving me t... Sep 10 2006, 08:05 PM tasp QUOTE (ngunn @ Sep 10 2006, 03:05 PM) On ... Sep 11 2006, 02:42 AM |
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