Posted on 04/15/2016 5:23:58 PM PDT by MtnClimber
While planning the lunar landings, Nasa had a decision to make: What route would they use to reach the Moon? It was one of many that needed to be made, but little did they know then, it would have an important effect of the survival of the ill-fated Apollo 13 crew.
This Sunday, 17 April, marks the safe return of James Lovell, “Jack” Swigert and Fred Haise after almost 88 tense hours on board their critically wounded craft thanks to that stroke of luck. The drama started unfolding at almost 56 hours Ground Elapsed Time (GET), meaning it was the evening of 13 April in Houston. Shortly after a live television broadcast, Mission Control had asked Apollo 13 to run through some standard checks.
"13, we've got one more item for you, when you get a chance. We'd like you to stir up the cryo tanks,” said capsule communicator Jack Lousma at Mission Control. The purpose of stirring the cryogenic tanks containing the hydrogen and oxygen was to give more accurate readings of how much gas was left. But because of an electrical fault, one of the oxygen tanks exploded. Initially the crew thought a meteoroid had hit them, but it soon became apparent they were losing oxygen. “It looks to me… that we are venting something,” replied Jack Swigert. “It’s a gas of some sort.” The clock was ticking. The explosion on board Apollo 13 marked the start of one of the greatest rescue missions in human exploration, but the three crewmembers owed their lives to a decision made years previously.
(Excerpt) Read more at bbc.com ...
Boiling in a vacuum is not due to heat. But it is a heat transfer to the ambient.
Space is near absolute zero.
I’m rather shocked that they were able to maintain 38F.
38F is 311K. In perspective, that’s quite hot. As for humidity, people expel a lot of water vapor.
Surface area versus enclosed volume plays a role in what form thermal management takes. The gold foil encasing space vehicles is a radiant barrier to block absorption of heat from the sun. The spacecraft were also engineered for a certain heat load which included dissipation from electrical equipment operating within the craft. And the ship was designed with an electrical heating system, as the engineering decisions were biased for the natural equilibrium to be on the cooler side.
The cold was bad enough; but, the crew’s source of water was the waste stream of the fuel cells-—hydrogen combined with oxygen results in electricity and water. The crew was sufficiently short of water to affect how much they could consume of food, thus less calories to burn fighting off the cold. Fat calories are more easily burned from exercise but little option for movement is available in the cramped spaces.
The movie followed the report.
But the report didn't follow the physics.
Those guys were literally in a vacuum bottle. Vacuum bottles keep hot things hot because of the vacuum. People run hot, compared to space. Also, the walls of the LM were not insulated. You're supposed to be in a space suit when you use the thing under normal conditions. So why was it only 38 degrees inside, when it was over 200 degrees colder on the other side of the aluminum hull? Try that in Alaska during winter, see how cold it gets.
Doesn't add up either way. Should have been way colder with no people in it, or way hotter with people in it.
Boiling is always a combination of heat and pressure.
Yes it is a vacuum and what does a rocket engine push against to propel itself? The vacuum kept the astronauts from being imeadiately flash frozen. That’s how cold 2.7K is.
In addition to being in the extreme cold of space, the LM was exposed to sunlight on the trip. 38 F is quite reasonable in those conditions.
Under normal conditions they used refrigeration units, hooked to a pair of deployed CM radiators, I believe. The gold foil would just make the internal heating worse. The problem is getting rid of the internal body-generated heat, not solar heating, although that adds to it. As I said, ISS runs huge heat radiators. It's a known issue.
Of course it about heat transfer and pressure. But the boiling would not be due to heat added, but to pressure lost.
It’s amazing what you can do with slide rules. Just think, if they had used Common Core, we’d still be waiting to get there.
They were in pressurized space suits which helped retain heat even in a 38F environment.
The rocket exhaust pushes against the spacecraft. The vacuum doesn't allow the release of heat from the insulated CM. The bodies of the astronauts generate huge amounts of heat. That heat didn't go anywhere once the refrigeration units failed for lack of power. Their problem therefore also included getting back before they overheated and died. The International Space Station has the same problem on a much bigger scale, which it also solves with refrigeration units and huge heart radiators. So they were hot, not cold. Period.
The boiling point of water is about pressure. It does happen to transfer heat to the ambient environment.
They weren't in their suits - they were too hot, not too cold.
Even the moon suits carried refrigeration units on their backs, and they certainly weren't in those - they wouldn't fit, and there were only two anyway.
>> in truth, they’d roast by their own body heat.
Do you “roast” on a 99 degree day?
It’s not possible for the interior of the capsule to exceed that temperature solely from their “own body heat”.
And as their heat radiates out from the capsule the temperature can only drop.
Physics is hard!
They were not in pressurized suits.
The interior temperature dropped to 38 degrees and moisture did condense on everything.
http://history.nasa.gov/SP-350/ch-13-5.html
What part of "vacuum" don't you get? Are you in a vacuum on a 99 degree day? Is that 99 degree day made from a 99 degree sun? What does that have to do with human bodies constantly pumping out 99 degree heat? Is there an atmosphere to dissipate the heat on a 99 degree day? Where is that dissipation atmosphere in space? If those bodies keep pumping out 99 degrees into a sealed vacuum bottle that can't release any heat, where will that heat go? If I wrapped you up in a down blanket on a 99 degree day in a sealed room, would your temperature go up? Would you overheat?
Physics is harder for some people than others.
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