Enceladus Plume Search, Nov. 27 |
Enceladus Plume Search, Nov. 27 |
Nov 24 2005, 04:01 PM
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
Interesting item in the science plan kernel (S16) just released to the NAIF website:
OBSERVATION_ID: S1629 SEQUENCE: S16 OBSERVATION_TITLE: Plume Search SCIENCE_OBJECTIVE: Hope to detect/observe plumes, whether from volcanic activity or geysers. OBS_DESCRIPTION: Point and stare. SUBSYSTEM: ISS PRIMARY_POINTING: ISS_NAC to Enceladus (0.0,5.0,0.0 deg. offset) REQUEST_ID: ISS_018EN_PLUMES001_PRIME REQUEST_TITLE: ENCELADUS Geyser/Plume Search REQ_DESCRIPTION: 1;ENCELADUS Geyser/Plume Search 1x1xNPp -- 3 different exposures BEGIN_TIME: 2005 NOV 27 19:00:00 UTC END_TIME: 2005 NOV 27 20:00:00 UTC -------------------- |
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Dec 2 2005, 08:14 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
The question that comes to my mind is:
If "warm" ice is convecting towards Enceladus' surface and then fountaining out of these south polar vents in significant quantities, could this have been happening for a very large percentage of Enceladus' existence? Do we have any clue of how much mass is entrained in the E ring? And can we even estimate the rate of mass lost from Enceladus due to this process? Because, for example, even if it's only losing a few tons of material a day, after billions of years, such venting would significantly reduce the mass and size of the body. And what would happen to an icy moon that has lost a significant amount of mass from within -- wouldn't there be signs of global crustal compression? I guess it depends on what's heating the interior ice and forcing convection of "warm ice" to the surface. Since tidal heating seems unlikely for such a small body, perhaps it's radiogenic? Maybe Enceladus happened to form around a rocky core that, for some as-yet-unguessed reason, had an anomalous amount of radiogenic minerals within it? If that's the case, then maybe Enceladus started out a lot bigger and has been losing mass -- and size -- for billions of years. Otherwise, you'd have to think that the activity we're seeing now is relatively rare, and we're lucky to be seeing it... -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Dec 2 2005, 11:18 AM
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#3
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
Interesting comments from Dr. Carolyn Porco:
"We suspect it could be caused by cold vents that lead from somewhere in the subsurface, perhaps as far as 1 kilometer down. Water ice is sublimating (changing directly from a solid to a gas state) and the vapors are coming off and building up to high pressure." http://dsc.discovery.com/news/briefs/20051...eladus_spa.html Since the e-ring has been determined to be particulate, maybe these sublimating water vapor jets have enough pressure to pick up ice particles and send them into space with escape velocity? Based on a web calculator I get 240 m/sec for escape velocity at the surface of Enceladus. Also from the article: "What's puzzling us is how it's getting hot enough," Porco said. "We're still in a quandary over how you'd get this much energy." -------------------- |
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