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Post by sts60 on Nov 16, 2007 16:03:41 GMT -4
In this video the idea that the soil kicked up by the rover encounters atmosphere is discussed. It's pointed out that the soil clumps when it encounters atmosphere. I can see he clumps. ... I think he's right about the soil encountering atmosphere. It would not have clumped in mid-air if it had been on the moon. Apologies for the thread necromancy, but as part of working on a lunar power source study, I was looking at Apollo LRV experience with containment of the dust ejected by the wheels, and found this (note: 8 MB PDF) study, in which an LRV tire was driven around inside a vacuum chamber over simulated lunar soil, all at 1/6 G in a "Vomit Comet" flight. My goodness! If rocky's mad research skillz hadn't been confined completely to YouTube and random HB sites, he could have waved this around triumphantly. Of course, later on the study points out: Now, I have read that the lunar soil is so clumpy because of a lot of jagged particulates - which have been cited as an inhalation hazard for future long-stay crews as they bring the stuff into airlocks. I suppose the truth is some combination of the two. If anybody knows any more about it, please chime in. * Note: 760 torr ~ 1 atmosphere; 1 torr = 1 mm Hg pressure.
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Post by AtomicDog on Nov 16, 2007 17:49:09 GMT -4
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Post by JayUtah on Nov 16, 2007 17:49:41 GMT -4
I suppose the truth is some combination of the two. If anybody knows any more about it, please chime in.
The truth is indeed some combination of the two. Chemical and thermophysical (i.e., "cold welding") cementation was considered in the Apollo 11 Preliminary Science Report. The implication at that time was that any application in which lunar dust were to be compressed or displaced at high rates would expect an uncommonly high degree of resistance due to the cementation that occurs when clean bodies rub under compression or agitation. This was not fully considered for the LRV since ejecta management did not rely on the clumping behavior of the material but solely only its likely aggregated trajectories.
Physical matrixing of lunar regolith was generalized from similar soil mechanics work in terrestrial particulates in which jagged particles exhibited certain cohesion modes (e.g., higher angles of repose) than rounded particles. Lunar regolith is composed of varying proportions of jagged, irregular particles and larger spherules. Thus the mechanics of cohesion vary from place to place on the surface.
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Post by JayUtah on Nov 16, 2007 17:53:06 GMT -4
The chemical reactiveness of clean body particulates is a concern. Where drawn into an oxygen environment, they may provide toxicity factors for human occupants or corrosion factors for machinery.
The jagged particles are uncommonly abrasive, which property wreaks havoc on machinery that depends for correct operation on tight tolerances, such as suit seals and drive line bearings. There is also the mechanical effects of the inhalation hazard -- jagged particles will lodge more readily in pulmonary alveoli.
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
Posts: 1,453
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Post by Al Johnston on Nov 16, 2007 18:06:32 GMT -4
jagged particles will lodge more readily in pulmonary alveoli. One reason why asbestos is so nasty.
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Post by Joe Durnavich on Nov 16, 2007 18:50:59 GMT -4
The jagged particles are uncommonly abrasive...The really jagged particles are the agglutinates. Agglutinates are grains that have been fused together by micrometeorite impact. They make up a good portion of the regolith. See page 9 of this for a picture: Contamination Control of Dust and Volatiles
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Post by randomguy on Jan 29, 2010 10:17:45 GMT -4
Your old friend rocky/cosmored has decided to spread his wisdom far and wide. Now, I cannot read up on the good stuff about my beloved San Antonio Spurs without having to have "moon hoax" stupidity dumped on my head. www.spurstalk.com/forums/showthread.php?t=144487Not exactly sure what rift in the time space continuum led his fevered brain to pick a basketball forum to spam his, um, unique brand of thinking, but now we are cursed with having to put up with it. Sigh.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jan 29, 2010 11:00:13 GMT -4
If this guy ever shows up on a Cleveland Cavaliers' forum, I might be impelled to join in the fray.
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Post by randomguy on Jan 29, 2010 13:48:41 GMT -4
If this guy ever shows up on a Cleveland Cavaliers' forum, I might be impelled to join in the fray. ;D Go Spurs!... back to topic, sorry for the interruption.
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Post by echnaton on Jan 29, 2010 19:26:57 GMT -4
my beloved San Antonio Spurs I thought the Rockets were the favorite team here.
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Post by Grand Lunar on Feb 1, 2010 12:01:18 GMT -4
Your old friend rocky/cosmored has decided to spread his wisdom far and wide. Now, I cannot read up on the good stuff about my beloved San Antonio Spurs without having to have "moon hoax" stupidity dumped on my head. www.spurstalk.com/forums/showthread.php?t=144487Not exactly sure what rift in the time space continuum led his fevered brain to pick a basketball forum to spam his, um, unique brand of thinking, but now we are cursed with having to put up with it. Sigh. That stinks. He continues to spread his stupidity on YouTube as well, under the name FatFreddy. Weird name. I now have the image of Rocky as being like Micheal Moore. Wonder what his excuse for LRO images is supposed to be?
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Post by echnaton on Feb 1, 2010 13:10:15 GMT -4
He continues to spread his stupidity on YouTube as well, under the name FatFreddy. Weird name. Does he have a cat?
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Post by Count Zero on Feb 1, 2010 21:43:30 GMT -4
;D You win one (1) internet!
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Post by echnaton on Feb 2, 2010 10:40:42 GMT -4
;D You win one (1) internet! Do I get to collect tolls or trolls?
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Post by PhantomWolf on Feb 2, 2010 15:41:58 GMT -4
Pity you can't just toll the trolls.
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