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Post by sts60 on Jun 8, 2005 22:11:59 GMT -4
Remember in the movie Apollo 13 how they were shivering with everything powered down to the bare minimum? There was a nice litte 1500 W or so of heat cranking away... just a few feet away, attached to one of the LM's legs, was the SNAP-27 heat source and generator.
Much discussion went on about how to get it inside just for the heat, but apparently it just wasn't feasible. Let alone trying to figure out how to use its electrical output.
I never really thought of that, and I know it's not news to a lot of people, but my boss was talking about it and I thought it was kinda cool. So close, and yet so far...
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Post by Data Cable on Jun 9, 2005 6:06:21 GMT -4
Yeah, I'd think a cabin repress would be just about the last thing they'd want to attempt, given the narrow margins availible at the time. (And silly me, for some reason I used to think that they compressed the cabin air into a tank before opening the hatch, rather than just waste it by venting into the vacuum.)
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Post by martin on Jun 9, 2005 9:34:39 GMT -4
"Earth diameter is 7,900 miles, and Moon diameter is 2,160 miles. It takes on average 90 minutes to complete one Earth orbit, so one Moon orbit should take roughly 25 minutes." - Sam "NasaScam" Colby I thought on this some more. When someone is travelling around the moon in 25 minutes, there is need for quite a lot of fuel to do this. But I am also calculating that the force experienced by this person is almost three times earth surface gravity. This will not be so pleasant, will it? Martin |
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Post by sts60 on Jun 9, 2005 10:10:40 GMT -4
Well, no, because they're in free fall. On the other hand, if you were standing on this high-G Moon, the life of a couch potato would be attractive...
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Post by papageno on Jun 9, 2005 10:23:19 GMT -4
Well, no, because they're in free fall. On the other hand, if you were standing on this high-G Moon, the life of a couch potato would be attractive... You can (free fall) orbit around the Moon in 25 minutes only at a certain altitude. If you want to do it in 25 mins at a different altitude, you need the engines to provide the appropriate acceleration to stay at that altitude, in which case it is no longer free fall and the astronauts would feeel the effects of that acceleration. |
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Post by martin on Jun 9, 2005 10:34:29 GMT -4
Well, no, because they're in free fall. On the other hand, if you were standing on this high-G Moon, the life of a couch potato would be attractive... But to orbit the moon in 25 minutes without acceleration from engines, the radius of orbit must be smaller than the radius of the moon, then you have a problem of friction with moon rocks ;D ;D ;D If travelling around the moon in 25 minutes just above the surface, then the accelartion towards the centre is more than three times earth surface gravity. Difference between this force and the moon surface gravity, which is small fraction of earth surface gravity, is force experience by astronauts. If travelling in 25 minutes at a higher radius, then the force is larger... Martin Edit - I see what is happened, you are changing mass of moon to allow orbit in 25 minutes, I am holding mass fixed and using engines to go faster than natural orbit period. So this is why we are coming to different answers... |
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Bob B.
Bob the Excel Guru?
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Post by Bob B. on Jun 9, 2005 10:35:32 GMT -4
Well, no, because they're in free fall. On the other hand, if you were standing on this high-G Moon, the life of a couch potato would be attractive... I just performed a few calculations to satisfy my curiosity. Let's assume a body orbits the Moon in 25 minutes at an altitude of 111 km (60 nautical miles). What would the mass of the Moon need to be to hold the body in this orbit? Answer: 1.662E+24 kg This means the Moon's density would be 75.6* g/cc versus 5.5 g/cc for Earth. (So much for the hollow Moon theory.) The acceleration of gravity at the Moon's surface would be 36.7 m/s^2, or about 3.74 times Earth. * This is 4 times the density of uranium. |
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Post by martin on Jun 9, 2005 10:40:16 GMT -4
The acceleration of gravity at the Moon's surface would be 36.7 m/s^2, or about 3.74 times Earth. Nasascam can use this also. If orbit of moon takes 25 minutes, then moon must have very high gravity, and films of astronauts show low gravity. Hmm... ;D ;D ;D |
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Post by JayUtah on Jun 9, 2005 11:51:32 GMT -4
A fun computation would be the difference in ocean tides with this "new" moon.
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Post by martin on Jun 9, 2005 14:07:22 GMT -4
A fun computation would be the difference in ocean tides with this "new" moon. Force is twenty times more, but if tides respond in a linear way, I do not know... Martin |
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jun 9, 2005 16:54:36 GMT -4
A fun computation would be the difference in ocean tides with this "new" moon. I don't know about tides, but I just calculated that this new moon's sidereal period would be 24.3 days instead of the current period of 27.3 days. |
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Post by martin on Jun 9, 2005 17:21:11 GMT -4
A fun computation would be the difference in ocean tides with this "new" moon. I don't know about tides, but I just calculated that this new moon's sidereal period would be 24.3 days instead of the current period of 27.3 days. And lunar module can not take off with the small engine it has... This is very strange. Soon we will calculate entire physics and astronomy of this alternate universe ;D ;D ;D Martin |
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Post by JayUtah on Jun 9, 2005 19:10:14 GMT -4
Tide height would not be a linear function of the moon's gravity. That's what makes it a fun computation.
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Post by Data Cable on Jun 10, 2005 0:32:01 GMT -4
Wow, been using that quote in my sig for years over on BABB... first time it's actually generated anything beyond a one-off passing comment. ;D
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Post by jaydeehess on Jul 4, 2005 23:27:43 GMT -4
I recall hearing a bit concerning the number of people Earth-side that were brought into working on various aspects of the problem of getting Apollo 13 home and that one group of mathematicians at a Canadian University received a call and were asked to take on some calculations. That is as much as this poor excuse for a memory retained. Does anyone have any idea of what I am talking about?
The details I would like are;
Who were the group of Canadians?
What university were they from?
What calculations were they tasked with?
Also, about Apollo 13, when the astronauts do the manual control for Earth orbit injection, just how difficult is that. My idea of an analogy would be that it was as difficult as a first time carrier landing, difficult, nerve-racking but doable.(and if my poor excuse for a memory actually dragged that analogy up without proper referencing forgive me for plagerism),
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