"Dewdrop" spotted on Titan..? |
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"Dewdrop" spotted on Titan..? |
 Dec 16 2008, 07:15 AM
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 The Poet Dude  Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60  |
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Dec 16 2008, 08:44 PM
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#2
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Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
Would methane dew really collect on Huygens? I would expect the probe to be warmer than its surroundings, not colder.
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Dec 17 2008, 04:14 PM
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#3
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 Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
The last 50km of the descent exposed Huygens to colder temperatures. I recollect that methane was evaporated from the surface by the 'hot' intake for the mass spectrometer. However, I expect that the rest of the probe's exterior was cold, being well insulated from the warm interior.
http://www.obspm.fr/actual/nouvelle/nov05/titan.en.shtml |
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Dec 17 2008, 04:36 PM
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#4
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 Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
Also, keep in mind that Huygens was thermally insulated pretty well so on the outside it could have conceivably cooled to ambient temperature.
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Dec 18 2008, 12:04 PM
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
You know it's nice to remember we have pictures from the surface, I had not seen that in many months and it brings back a nice warm feeling of a successful mission.
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Dec 18 2008, 02:21 PM
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#6
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 Member Group: Members Posts: 610 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
QUOTE (ugordan @ Dec 17 2008, 11:36 AM)  Also, keep in mind that Huygens was thermally insulated pretty well so on the outside it could have conceivably cooled to ambient temperature. exactly - see my analysis of the thermal interaction of Huygens with its environment http://www.lpl.arizona.edu/~rlorenz/huygens_thermal.pdf |
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Dec 18 2008, 07:41 PM
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#7
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Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
As far as I can see you estimate in the paper that the skin temperature of Huygens was 5 K above ambient at landing rising to "a few tens of K above ambient" which I should think would preclude condensation.
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Dec 19 2008, 08:14 AM
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#8
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
QUOTE (tty @ Dec 18 2008, 02:41 PM) As far as I can see you estimate in the paper that the skin temperature of Huygens was 5 K above ambient at landing rising to "a few tens of K above ambient" which I should think would preclude condensation. From the link in the opening post: "Scientists think heat from the probe caused humid air to rise and condense on the cold edge of the craft." I think protruding edges would be closer to the ambient temperature than would the overall surface temperature of the probe. And since the ambient temperature quickly rose 24 degrees before impact: "....just prior to surface impact, although the environmental temperature increases from 70 to 94 K...." (from Ralph Lorenz's paper), I can see how it would be possible for protruding edges such as those around the DISR to be colder than the surface ambient temperature for a while after landing. |
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Dec 19 2008, 02:48 PM
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#9
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Member Group: Members Posts: 610 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
QUOTE (tty @ Dec 18 2008, 02:41 PM) As far as I can see you estimate in the paper that the skin temperature of Huygens was 5 K above ambient at landing rising to "a few tens of K above ambient" which I should think would preclude condensation. As long as a surface like the DISR baffle is cooler than the ground spot heated by the lamp you can have condensation |
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