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Post by grashtel on Jul 10, 2006 22:21:48 GMT -4
After roughly 100 hours of continuous sun exposure, the moon's surface temperature during this feather experiment was only about 130 F? That's about the same temperature as a hot day in Death Valley California and it only has sunlight for 12 hours a day. Its also an awful lot hotter than Antarctica after over 4000 hours of exposure to sunlight. Exposure time is only part of the story when working out the temperature of a surface.
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Post by freon on Jul 10, 2006 23:00:53 GMT -4
It's possible to cook eggs on sidewalks at that temperature . All you need is surface temperature of 144F-158F to achieve this.
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Post by freon on Jul 10, 2006 23:07:27 GMT -4
Weren't most of the Apollo landings, especially Apollo 16 more centered around the moon's equator where the sun's light would be more direct than if they had landed at the moon's poles?
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Post by PeterB on Jul 10, 2006 23:26:14 GMT -4
Freon
Yes, the landings generally were close to the equator. But they also landed early in the lunar morning when the Sun was still low in the sky. Therefore, the Moon was still warming up from the deep freeze of the previous lunar night.
Also, while the temperature you describe may be hot enough to cook an egg (though I think I'd go for a higher temperature) have you actually subjected a feather to that temperature to see what it does?
Finally, the temperature of the surface of the Moon is irrelevant when it comes to the temperature of the feather sitting inside a pocket of a white space suit in a vacuum. The feather isn't going to be subjected to the Moon's surface temperature. Instead, it's going to be close to the temperature of the object it's in contact with - the inside of the pocket of the white space suit. The feather only touched the 85 degrees C Moon surface when it landed on the Moon. But by that point, the experiment was over.
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Post by Count Zero on Jul 11, 2006 0:33:55 GMT -4
The feather only touched the 85 degrees C Moon surface when it landed on the Moon. More precisely, it landed on soil that Scott had kicked-up repeatedly while moving around. It was probably cooler than the surrounding, undisturbed soil. The FeatherI'm curious about what would happen to objects exposed to high heat in vacuum. Without air they wouldn't oxidize or char (the temperatures we're talking about are too low for that anyway). If they had a significant percentage of water in their makeup you'd see shrinkage as they dessicated. Feathers are basically dry. I could be wrong, but I wouldn't think that much of anything would happen to one on the surface.
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Post by PhantomWolf on Jul 11, 2006 5:50:21 GMT -4
A bunch of litter louts weren't they.
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Post by Count Zero on Jul 11, 2006 7:08:30 GMT -4
A bunch of litter louts weren't they. Oooh yeah. Apollo 15 was the only mission where they had the TV mounted on a tripod showing them setting up rover (after deployment). On the DVD you can see them clipping-off several tie-downs and tossing them aside. I don't know if the astronauts were aware of it at the time, but just a routine flick of the wrist made those little things go sailing up & out of the frame!
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Post by PhantomWolf on Jul 11, 2006 7:46:12 GMT -4
Yeah, I have the Apollo 15 DVDs and my comment was remarkably the same as above, lol. It seems we've littered on nearly every planet in the Solar System we can get our mitts on.
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Post by freon on Jul 11, 2006 10:43:44 GMT -4
Did I grasp this correctly? The terminator and the previous lunar night passed about four days earlier approximately 100 hours prior. The surface of the moon had been heated by the sun now for 100 continuos hours and darkness at the site wouldn't fall for another 10 days or so. The Apollo 16 crew landed at about 10 degrees from the moon's equator and the surface temperature was around 150-185F during the experiment. And as the feather lay on the surface of the moon, nothing happens to its condition. Nobody was curious because the experiment was over by then.
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Post by sts60 on Jul 11, 2006 11:23:35 GMT -4
Why should a visible change happen to the feather while they were there?
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Post by Jason Thompson on Jul 11, 2006 11:48:39 GMT -4
Apollo 15, not sixteen, performed the hammer and feather experiment. No-one looked at the feather again because:
a) the only purpose of the experiment was a verification of Galileo's principle of falling masses, which was really just a piece of frivolous fun because it had already been experimentally verified on Earth. The benefit of being on the Moon was that it allowed the use of an object that would otherwise be subject to air effects, i.e. a feather.
b) Why should anyone be interested in what happens to a feather on the lunar surface? If they were interested, on that scale a lab setup here on Earth could be used to provide a hot surface in a vacuum.
c) It was one of the last things done at the end of the final EVA. The astronauts were then occupied packing up the LM and getting ready to depart. They were back in the LM and repressurised about half an hour after the hammer and feather.
The terminator and the previous lunar night passed about four days earlier approximately 100 hours prior. The surface of the moon had been heated by the sun now for 100 continuos hours
As I and others have pointed out, there is no reason to assume the paricular surface the feather was dropped on had been subject to 100 hours of sunlight. It was right next to the LM. It may have been in shadow for some or all of that period, either from the LM itself or from other things like the rover or some experimental packages which may have been placed on it. It had definitely been kicked up by the astronauts, and the soil under the top layer had not been subjected to any sunlight. The soil where the feather fell was almost certainly cooler than the surface soil that had been warmed continuously.
Again I come back to the simple question: why are you so fixated on this point?
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Post by Jason Thompson on Jul 11, 2006 11:53:54 GMT -4
OK, I just watched the clip online. The ground that the hammer and feather were dropped on was in sunlight, but it was not far outside the shadow of the LM, and it was definitely covered in fotprints and churned up. I would venture to say it is possible that that particular piece of ground was in shadow earlier in the mission, but without more precise information I can't be sure. However, it seems highly unlikely it was as hot as undisturbed soil that had been illuminated for 4 days straight.
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Post by scooter on Jul 11, 2006 15:22:54 GMT -4
OK, I swear I'm going to go into the back yard, find a birdie feather, the toss it onto a 180 degree frying pan...what should happen. Will it disintegrate? Melt? Burst into flames? Float? Become invisible?
What is the "expectation" here, and why should it do what my experiment does?
Dang, I wish he's dropped a sheet of newspaper instead!!!
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Post by Count Zero on Jul 11, 2006 17:12:43 GMT -4
[moonman]Don't forget to spray your frying pan with vacuum, first![/moonman] ;D
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Post by freon on Jul 11, 2006 20:16:36 GMT -4
For the record, I've never said or implied any other mission than Apollo 16. I was just curious if the feather was 1. In the suit at all times - taken in and out of the pressurized cabin mulitiple times throughout the mission during the EVAs. What affect that would have had on its condition. 2. If they observed what the solar radiation and surface temperature did to it, since bird feathers are organic, contain oils, keratin cells, etc. Did it last long?
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