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On a ring origin of the equatorial ridge of Iapetus
Guest_AlexBlackwell_*
post 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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tasp
post Sep 10 2006, 06:00 PM
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Of course, the most interesting bit of the ridge system (the highest parts) are right at the limb of the existing Cassini images. And there is a tremendous amount of subsequent cratering damage all along the ridge structure.

(oh, to have seen it shiny and new . . . . )


That the highest end is discontinuous is a concern. More cratering damage? Perhaps subsidence of the crust beneath, or collapse of the steeper walls occured.

More pictures are needed. And hopefully we get them in 2007.


Additionally, imagine with the minds eye if you will, the lowest edge of the ring, contacting the very highest spot along the Iapetan equator. As the chunks and particles impact the pinnacle, there will be a spray of pulverized ring material released at the contact point. Any material directed upward will interact (ie. decelerate) any material still orbiting in the ring system above the contact point at that instant.

Some of that material will fall to the surface, downrange of the contact point. Some of that material, even though very slightly decelerated, will still manage to complete one more orbit and return to the contact point.

Some of the material, though, will be decelerated into an orbit that is now eliptical. Depending on how close to the surface such doomed ring particles get, they may intercept other high spots along the ground track and accumulate. The lowest objects may get snagged quite aways around Iapetus, where as a particle in a slightly higher orbit might clear that obstruction, and nail another further along.

I think the ring system can emplace at a main primary point along the equator, but there could be a small percentage of materials that may accumulate almost all the way around Iapetus at more than one other secondary location.

Note, the majority of the materials decelerated by the spray above the conact point will fall to the surface along the ground track up to 90 degrees around from the highest spot along the ridge, and this is why the ridge smoothly slope downward from the high spot. Even the 2 nonparallel diverging ridge attendent structures do so.


If one could look down upon either pole of Iapetus and see the silhouette of the equator, the highest heights would all approximately describe an ellipse of elevations around Iapetus.

We also would not expect to see ring material deposits in large deep basins (such as the famous landside basin photographed by Cassini earlier in the mission), there being no eliptical path from the contact pinnacle to the floor of the basin that does not intersect an obstruction along the way. Where the ridge structure is seen, and where it isn't visible, all tell us how the material was organized as it emplaced.

An internal geological process could not be expected to generate structures with all these characteristics. A lack of discontinuites, fissures, or ridge like structures in the deep landslide basin aligned with the equator is also telling us much about the origin of this amazing ridge structure.
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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
- - hendric   I still don't see how the two divergent ridges...   Sep 8 2006, 05:54 PM
|- - TritonAntares   QUOTE 37th DPS Meeting, 4-9 September 2005 Session...   Sep 8 2006, 08:29 PM
||- - tasp   QUOTE (TritonAntares @ Sep 8 2006, 03:29 ...   Sep 9 2006, 05:28 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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