.......and why was the crew cabin on the A13 LEM said to be cold on the way back? This question will require a basic knowledge of physics to answer, and without relying on any of the Apollo details or specifics.

Answer: space is colder than an astronaut. Heat tries to reach an equalibrium, therefore will travel from a warmer area to a cooler one. This makes the warmer area cooler and the cooler area warmer.

Now; why is this in CT?

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I would submit that an accurate answer using basic physics, using no specifics or details of Apollo, is as simple as "thermodynamics" or the (slightly) less accurate "radiation".

Why do you need Jay for this? Wouldn't a basic physics textbook do just as well?

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And you, to whom adversity has dealt the final blow
With smiling [faces] lyin' to ye' everywhere ye' go
Turn to, and put out all your strength of arm and heart and brain
And like the Mary Ellen Carter, rise again.

Answer: space is colder than an astronaut.

Space is not cold at all. For our practical purposes, it's a vacuum. There is nothing to be cold (or warm).

Now; why is this in CT?

NEO, in case you haven't been following the other thread, IDW has questions he wants addressed about the veracity of Apollo. He started one thread about the structure of the discussion, now he is beginning the discussion itself.

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"Transport of the mails, transport of the human voice, transport of flickering pictures - in this century, as in others, our highest accomplishments still have the single aim of bringing men together." St. Exupery

I'll certainly defer to Jay's knowledge of the LM ECS because I honestly don't remember if it had much in the way of active heating or not. But power management was of great concern during the A13 abort. So, if cockpit active heating was prioritized off the list of things they had to have in order to survive, radiative heat loss would have resulted in a cold cabin.

Edit to add: Asking details and specifics about the Apollo spacecraft and then placing "Apollo details or specifics" off limits just doesn't make much sense. Please ask your questions. Support provided for the answers will either be relevant or not. I don't think it's fair of you to cherry pick the facts that may support a valid answer.

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Brett
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Apollo suits and space craft used a porous-plate sublimator to reject excess heat. you can by one here if you want.

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Living on Earth may be expensive, but it includes an annual free trip around the Sun.

I would recommend to IW that he not only asks his questions but also clarifies what he believes the answers to be (he obviously has his argunments well thought out, might as well present each on all at once for discussion) rather than just ask simple questions that will be used as bait to lead someone to his "aha! I gotcha!" moment.

IW, just go ahead and tell us how you think the Apollo was cooled and how it pertains to your conspiracy belief. Save us a lot of woo woo time here, please.

Besides, no offense, but the mere fact that you asked the question in the manner you did indicates you do not understand basic physics or thermodynamics, therefore you will not understand the correct answer either.

Your right when you claim all that is required is an elementary knowledge of thermodynamics. Doesn't Jay possess such knowledge? It is the basic physics that cannot be argued against that will prove or disprove my contention that the spacecraft would be unable to shed heat in the vacuum of space through the conversion of heat energy buildup from Solar radiation and internal heat sources into thermal radiation which the spacecraft can shed in space.
I have used a car parked in the Sun as an example in the past. Two things though, the car is under the protection of the atmosphere and the magnetosphere, and air molecules are moving over it to cool it.

No; but I did follow the poster's recent posts to see where this might be coming from.
So; this did give me some indication as to an alterior motive, but I wanted an answer and was trying keep it innocent to avoid any kind of accusations.

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(Note - I've got to run to the airport. Here is a treatise I did last year on spacecraft (and astronaut) cooling. Although the first part is about the moon, it applies to objects in space as well, as both are in a practical vacuum. It does address Apollo 13 specifically.)

Let's talk about the "temperature on the moon". That phrase has led to a lot of confusion. You have no doubt heard that the temperature on the Moon varies from -250F up to 250F. I live in Texas, and in the summertime, the temperature gets up over 100F, so standing on the Moon must be like standing in an oven, right?

No.

If, on a hot summer day here in Texas, I walk out on the sidewalk barefoot, it's hot enough to cause pain. If I step onto the asphalt street, I will blister my feet. Why? 100F is less than two degrees above normal body temperature. The solid pavement is hotter than the transparent air because it absorbs more radiant energy from the sunlight. The light-colored concrete sidewalk may heat-up to 120-140F. The darker asphalt may get up to 180F or more.

When we ask, "what is the temperature outside?" we are asking about the ambient temperature of the air. On the Moon, there is no air, so when we ask about the temperature there, we are asking about the temperature of a specific object on the surface; a patch of dirt, a rock, a camera or an astronaut's spacesuit (and specifying whether it is the side facing towards or away from the Sun). Note that this varies: In my above example, the sidewalk was ~130F, but the asphalt was 180+ F. When a textbook says that it gets up to 250F on the Moon, it is referring to the surface of a black, solid object with its face perpendicular to the Sun at local noon.

The actual lunar surface is not black: It's about the same shade as asphalt (not the fresh-laid black stuff, but rather the dark/medium grey color it fades to after a few years). It heats up to roughly 200F. Mind you, the Moon is the same average distance from the Sun as the Earth. All things being equal, lunar regolith and asphalt should reach the same temperature. However, the asphalt is cooled somewhat because the air in contact with the pavement conducts away some of the heat (we can see it doing this: it causes the shimmering effect when we look across a hot parking lot). Also, daylight only last ~12 hours on Earth, but it's 14 days from sunrise to sunset on the Moon.

I said before that the pavement here in Texas can get up to ~180F. However, on a summer day I can go outside and walk on it barefoot with no discomfort. How? It's simple: I do it at 8:00am, before it gets anywhere near that hot. The Apollo astronauts did the same thing: They landed when the rising sun was only ~10 degrees above the horizon and the surface temperature was ~30F. When they left three days later (on the longest missions), the sun was still only half-way up the sky, and the surface temperature was a bit over 100F (yes, NASA did have the technology to make insulated shoes in the 1960s ).

(Allow me to state the blindingly obvious: The surface starts out cold because it has spent all night radiating its heat into space. As someone else already pointed out, when a surface is in the sun, it absorbs light based on its reflectivity (more reflective absorbs less energy) and its angle to the sun (a perpendicular angle to the light absorbs more than an oblique angle). When the same surface is shaded from the sun, it radiates heat as efficiently as it absorbs it - a black surface radiates faster than a light one.)

For astronauts, heat management is a crucial issue that requires careful engineering, whether they are on the Moon or in Earth orbit - Remember, they are at the same average distance from the Sun. In fact, the Earth is more reflective than the Moon, so astronauts & spacecraft in Earth orbit get more reflected energy than those on the Moon (even though the surface is much further away, there's a lot more area doing the reflecting). For spacecraft & spacesuits (which can be thought of as mini-spacecraft), the engineering solution is basically the same: Keep as much of the outside heat out and control the heat that's being generated on the inside to maintain comfortable levels.

Outside heat from direct & reflected sunlight is kept out by using a reflective outer layer, backed up by layers of insulation. When you look at the flimsy-looking outer covers of the Lunar Module, you're only seeing the reflective skin that covers the actual structural members and pressure vessels beneath. Interestingly, Middle Eastern nomads developed the same principle centuries ago: Those volumous white robes they wear serve the same function, and work better than shorts and a t-shirt to keep them cool in the desert.

Inside, heat is generated by electronics and by the astronauts themselves. On full-size spacecraft, most of the heat comes from electronics, and any excess goes to shielded radiators on the hull (on Apollo 13, when they lost power, they shut down the electronics and therefore their main heat source, which is why it got so cold). Men doing geology on the Moon, and building the International Space Station in orbit are basically doing heavy work for hours in an airtight rubber suit. Beneath the rubber, they wear something like long underwear that has a whole network of tubes. They pump water through the tubes to something called a porous-plate sublimator, which carries the heat away to space.

The smaller pieces of equipment on the Moon, such as cameras and experiment packages mainly relied on reflective outer casings. In these cases, keeping the dark lunar dust off of them was a major concern. On the EVA videos, you can hear some exasperation from the astronauts after the umpteenth request from Houston to dust-off the TV camera because it's overheating. Of course, the astronauts and the still cameras they carried were almost constantly turning this way and that, so individual surfaces spent as much time facing away from the Sun as towards it.

Hopefully this helps clear things up for you.

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"Transport of the mails, transport of the human voice, transport of flickering pictures - in this century, as in others, our highest accomplishments still have the single aim of bringing men together." St. Exupery

You don't need Apollo specifics to answer this question, it is elementary physics.


To answer the other apparent answer to my question,
To my knowledge there were no sublimators on the vehicles themselves, though I could be wrong. Does anyone have a technical description of the apparatus?

I'm certainly no expert on thermodynamics (as my college transcript can attest) but it is my understanding that most spacecraft are cooled by radiation.

I recently saw photos of the ISS showing radiators being installed, and the Shuttle has radiators on the inside of the payload bay doors. Additionally, I seem to recall the Shuttle having "flash evaporators" for cooling when the doors are shut.

As for the A13 situation, most of the heat generating electronics were shut off during the trip home. Without doing any research whatsoever, I'd assume that the CSM radiated heat faster than it was being generated internally by the crew and operational electronics. I don't know if any evaporative cooling was going on, but I'd assume the crew would turn it off if the cabin was getting cold.

With enough work, one could do a thorough analysis of the situation and determine if the temperature in the cabin was consistant with the amount of heat being generated (and absorbed from the sunshine) and radiated away.

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I may have many faults, but being wrong ain't one of them. -- Jimmy Hoffa

...and that would be a bad example.

Z28jerry was correct, if you don't understand the basic physics of why your question is improper, then how will you ever be able to understand the correct answer??

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"The facts gentlemen, and nothing but the facts, for careful eyes are narrowly watching." Isaac Asimov

Now my one question has branched out into two more.
One of you claims a sublimator was used to cool the vehicle and another claims A13 was cold because the 'heater' was turned off.

Guys, I don't think "You don't understand basic science." is the answer our Warrior is looking for.

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You asked the question, not Jay.

You need to consult a physics textbook. Heat radiates in a vacuum.

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And you, to whom adversity has dealt the final blow
With smiling [faces] lyin' to ye' everywhere ye' go
Turn to, and put out all your strength of arm and heart and brain
And like the Mary Ellen Carter, rise again.

The heat sources on the CSM included body heat and the electronics, with the latter providing most of the heat. On A13, most of the the electronics were shut off, removing the primary source of cabin heat. The CSM was covered in a mirrored insulation that was designed to reflect solar heat with layers of thermal insulation underneath that. The remaining A13 CSM heat sources simply did not produce sufficient heat to replace the heat lost to to space by radiance. So the capsule interior cooled.

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Living on Earth may be expensive, but it includes an annual free trip around the Sun.

The Apollo capsule was shiny.

But weren't the Mercury capsules black? If so, did they have cooling problems?

This answer highlights why "Apollo details or specifics" are indeed important to answer questions of "elementary physics" when it's applied to real world engineering. We're not talking about theoretical black bodies as is so often used in discussions of thermodynamics. Unlike the CM, your average car wasn't designed to reflect solar energy as a means of heat management. That's why some enterprising companies sell shiny silver panels to put in your car windshield.

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Brett
Peters Creek, Alaska
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Even on A13, after the accident, the crew attempter to maintain something resembling a "barbecue roll" of the spacecraft. The sun heated those parts of the spacecraft so exposed, while the "shaded" areas were radiating their heat away. Trying to maintain something of a equiluilibrium without overly heat or cold soaking any hardware parts.
They weren't able to really establish a good long duration roll, so mainly depended on rolling the stack 90 degrees every 30 minutes or so.
From the crew, closing the shades during one sleep period seemed to start some significant loss of heat input to the cabin (sun through the windows). This, and the loss of electronic waste heat (normally shedded through SM radiators) was apparently a contributor to the "excess radiational cooling" of the spacecraft.

Weren't they only in sunlight for about 45 minutes at a time?

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Brett
Peters Creek, Alaska
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What would stop Apollo from radiating to space? What makes it different from other spacecraft or the Earth for that matter?

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Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

How IDW reacts to this statement will be very "telling".

He could either say, "gee, I was wrong", which would indicate that he is objectively evaluating the evidence, or he could say, "no, you guys are wrong", which would "expose" him as just your typical, uninformed hoax believer.

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They were in the shade every twenty minutes.

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And you, to whom adversity has dealt the final blow
With smiling [faces] lyin' to ye' everywhere ye' go
Turn to, and put out all your strength of arm and heart and brain
And like the Mary Ellen Carter, rise again.

To be only a little more specific, a body radiates heat, and the amount of heat it radiates is an increasing function of its temperature. So the spacecraft is simultaneously heated (solar radiation, internal sources of heat) and cooled (radiation of heat out into space). If the amount of heating is greater than the amount of cooling, the spacecraft temperature will increase, which increases the rate at which it radiates energy into space. If the amount of cooling is greater than the amount of heating, the spacecraft temperature will decrease, which decreases the rate at which it radiates energy into space. Either way, eventually, an equilibrium will be reached (assuming constant conditions, that is, constant exposure to the sun, constant amount of heat generated from the inside, and the like) in which the spacecraft radiates out to space an amount of heat exactly equal to the amount it receives through solar radiation and from internal sources.

So the interesting question is not how the spacecraft was cooled - that's through radiation. The interesting question is what the equilibrium temperature of the spacecraft would be. This of course depends on its design (what is its shape, how much power do the electronics consume, things like that), so it's a little tough to determine that without using specific information about the Apollo crafts.

Unfortunately, you do need the Apollo specifics to know how they applied the elementary physics.

In your OP, you said, "This question will require a basic knowledge of physics to answer, and without relying on any of the Apollo details or specifics." (emphasis added) Have you decided that prohibition is no longer in effect?

Also, as has been pointed out by various posters, I think you need to explain to us how these elementary physics worked in the case of Apollo. The approach you have chosen places you at a distinct and unfair advantage, since you can then cherry pick and snipe at the responses and avoid giving us your views.

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On an 88.5 minute orbit?
You may have double divided somehow...

Anyway; didn't the other craft generate less heat in the first place?

Plus; I remember them opening the door alot.

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Numbers are not case sensitive. (me)

You don't need Apollo specifics to answer this question, it is elementary physics.

I thoroughly disagree. I reject outright the premise that the authenticity of Apollo's thermal behavior can be meaningfully discussed without knowledge of Apollo's detailed design that addressed thermal issues.

As to whether it is subject to "elementary physics," I'll have to wait until it's more clearly understood what level of knowledge is implied by that phrase.

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Clavius Moon Base

Now we see an example of several posters describing the same thermodynamic situation applied to Apollo, in their own words. Do these explanations make sense, IDW, or are they wrong in your view?

Apollo specifics must indeed apply here, as the spacecraft systems were designed specifically to deal with the thermal issues of the environment.