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peter eldergill
2007-Sep-17, 07:33 PM
While watching Apollo 13 on TV yesterday, they indicated that one of the problems with shutting down the computer systems was that the craft was too cold

I've scanned a couple of threads here indicating that too much heat seemed to be more of a problem. I'm a little confused, but do understand basic heat transfer

Are both heat and cold a problem, or what am I missing (and yes, I do know that Apollo 13 was not a documentary :surprised)

What am I missing? Did the computers and other systems emit that much heat? I know the human body emits quite a bit of heat

Pete

samkent
2007-Sep-17, 07:47 PM
The heat from the computer and other electronics is what kept the cabin warm. So warm that they needed a cooling system to remove the excess heat.

JayUtah
2007-Sep-17, 08:18 PM
The electronics generate more heat than they safely handle themselves, so the waste heat has to be conveyed to radiators. Otherwise they would overheat and malfunction. On the other side of the coin the spacecraft was naturally cold inside and borrowed some of that waste heat to bring it up to a livable temperature. This was done on purpose, understanding that it's usually easier to add heat when wanted than to remove it when unwanted. But that coupled the cabin temperature to the operation of the electrical system. The only way the cabin would be livable is when the electronics were operating. And that was a reasonable tradeoff since the designers weren't asked to plan for a time when the ship would be occupied but turned off.

ineluki
2007-Sep-18, 12:33 PM
What am I missing? Did the computers and other systems emit that much heat? I know the human body emits quite a bit of heat

To put it in a simply:

+ Incoming heat
- reflected heat
+ body heat
+ heat of the equipment
------------------------
= nice temperature

Change one of the above, and you will get more heat than you want or less than you would like.

ineluki
2007-Sep-18, 12:59 PM
Change one of the above, and you will get more heat than you want or less than you would like.

To add a real world example, right now, the temperature at my place is about 12°C, and the heat from my TV and PC raise the temperature in my room enough to be comfortable.

BigDon
2007-Sep-18, 01:00 PM
Pete, whenever we had to turn on the electronics of the Tomcat while on the ground we had to hook up these huge 1100 pound airconditioning units to keep the electronics from frying themselves. Major pain in the butt I might add. I recall once a stray cat crawled into the airline, but thats another story.

Swift
2007-Sep-18, 03:18 PM
Pete, whenever we had to turn on the electronics of the Tomcat while on the ground we had to hook up these huge 1100 pound airconditioning units to keep the electronics from frying themselves. Major pain in the butt I might add. I recall once a stray cat crawled into the airline, but thats another story.
Well, the aircraft was a Tomcat! Was this when you served on the Kitty Hawk? :D

NEOWatcher
2007-Sep-18, 04:22 PM
Well, the aircraft was a Tomcat! Was this when you served on the Kitty Hawk? :D
And did you solve the problem by flying over the Catskills?

Jim
2007-Sep-18, 04:45 PM
All right! If this devolves into another of those "my pun's better than yours" threads, I'm closing it! And no pussyfootin' around, either.

Swift
2007-Sep-18, 05:38 PM
All right! If this devolves into another of those "my pun's better than yours" threads, I'm closing it! And no pussyfootin' around, either.
Well!, that was a rather catty comment.

Fazor
2007-Sep-18, 05:48 PM
Ugh, these pun threads always turn out to be catastrophic!

peter eldergill
2007-Sep-18, 05:58 PM
It's all my fault...sorry...meow

Pete

sts60
2007-Sep-18, 06:21 PM
Maybe we should start a beer fund for the moderators. Anyone who makes a bad pun has to feed the kitty.

Fazor
2007-Sep-18, 06:35 PM
In that case, please scratch my last post. I'm too poor for that.

hplasm
2007-Sep-18, 08:44 PM
Maybe we should start a beer fund for the moderators. Anyone who makes a bad pun has to feed the kitty.

:silenced:

Swift
2007-Sep-18, 09:24 PM
In that case, please scratch my last post. I'm too poor for that.
I'm sorry, we can't do that. There is a claws in the BAUT rules against scratching posts.

DrivinWest
2007-Sep-18, 09:52 PM
I posted this in another thread (in reply to a conspiracy theorist who was certain that he'd proven that the Apollo landings were faked):

First, a little about myself: I've been an ISS flight controller (one of those guys in Mission Control with the headsets in front of the big screens) since 1999. My areas of concentration in that time have been ISS Guidance, Navigation, and Control and Environmental Control & Life Support.

The ratio of insolation to eclipse is dependant on the Beta angle. The Beta angle is the angle between the orbital plane of the ISS and the sun. It varies cyclically and predictably over the course of the year. At the time of my posting the ISS spends ~55 minutes of its orbit in the sun and ~35 in the shade.

(This effects the thermal profile of the ISS dramatically)

Yes, it does require massive radiators to remain cool and remain habitable. Clearly you don't understand why...

Yes, ammonia is one of the coolants used. Since ammonia in concentrated form is extremely dangerous to humans, interface heat exchangers are used to couple the ammonia loops outside with water loops inside.

So WHY is there a massive cooling system on ISS? To reject the heat created by the computers, batteries, power relays, payloads, etc. All this equipment turns electricity to heat and it gets hot - very hot. This equipment operates without the advantage of gravity-aided convection. To remedy this, the equipment is placed on cold-plates which transfer the heat to the internal water loop and then to the external ammonia loop. The heat is then rejected by the radiators.

The crew cabin tends to stay pretty close to a shirt-sleeve environment thanks to the all the heat that is generated in the station. Inter- and intramodule ventilation helps to even the temperature across the station's air volume (and ensure no pockets of Carbon Dioxide!).

Do you know what the Shuttle provides to ISS components which are en route to the ISS? Power. Why? To run heaters. Without the internal equipment running the hardware gets VERY cold in space. Every mission has a thermal constraint related to the payload - go without power long enough and your hardware will be permantly damaged by the cold. Even some powered and mated modules have "shell heaters" to prevent humidity from condensing on the cold hull.

So now you know - and that's half the battle.

-DW

It's a good question when it's posed as a question, not when it's stated incorrectly and used to support wrong conclusion a la our local tin-foil hat lot!

Nicolas
2007-Sep-18, 09:58 PM
Tin foil cat?

captain swoop
2007-Sep-18, 10:03 PM
careful, we don't want to be pun ished

ZappBrannigan
2007-Sep-18, 11:10 PM
http://icanhascheezburger.wordpress.com/files/2007/08/skeptical-cat-is-fraught-with-skepticism.jpg (http://icanhascheezburger.com/2007/08/02/skeptical-cat/)

PhantomWolf
2007-Sep-18, 11:19 PM
To be redone when I get it uploaded properly

Nicolas
2007-Sep-18, 11:47 PM
LOL, the Skeptical Cat.

KaiYeves
2007-Sep-19, 12:09 AM
Am I the only one who always cries at the end of Apollo 13?

pzkpfw
2007-Sep-19, 12:37 AM
Am I the only one who always cries at the end of Apollo 13?

No.

Even my wife did, who only saw the last few minutes.

Grashtel
2007-Sep-19, 12:52 AM
http://bighugelabs.com/flickr/output/lolcat1326026.jpg
Um, you might want to make sure that the sites you are embedding images form allows that in the future.

Occam
2007-Sep-19, 01:20 AM
Am I the only one who always cries at the end of Apollo 13?
Absolutely not. On the real Apollo 13, when I saw those chutes and heard their voices after the interminable wait of re-entry, I was leaping around, yelling, laughing and crying at the same time.

PhantomWolf
2007-Sep-19, 02:12 AM
Um, you might want to make sure that the sites you are embedding images form allows that in the future.

As far as I know it does, since it's an LOLcat generator and I made that one.

ZappBrannigan
2007-Sep-19, 02:41 AM
As far as I know it does, since it's an LOLcat generator and I made that one.
Mine is from http://www.icanhascheezburger.com, and they provide code for linking pictures.

However, when I right-clicked and chose "show picture in new window" on yours, I saw a little graphic that says, "bighugelabs.com. Do not direct link to images here. Save a copy instead. Thank you."

Grashtel
2007-Sep-19, 03:05 AM
As far as I know it does, since it's an LOLcat generator and I made that one.
It doesn't, well unless you made a little (136x102) image that says "bighugelabs.com. Do not direct link to images here. Save a copy instead. Thank you.", which given the context seems somewhat unlikely.

Swift
2007-Sep-19, 03:22 AM
Am I the only one who always cries at the end of Apollo 13?
Even though I've seen the movie a dozen times, at the end, when Gene Kranz signs off and sits down, I always get a tear in my eye.

I saw a TV program (maybe a PBS Nova) a few years ago about the real Apollo 13, where they interviewed Kranz a lot. At one point he talks about that moment in the mission and even he gets visibly choked up, even after all these years.

Count Zero
2007-Sep-19, 04:06 AM
That was the outstanding Apollo 13: To the Edge and Back (http://www.imdb.com/title/tt0180443/). I also saw that on PBS. It actually came out a couple of years before the Tom Hanks movie. It may have been what motivated him to make the movie. It certainly re-ignited my interest in Apollo. My only gripe about it was that they inexplicably omitted any photographs of the damaged service module (http://www.hq.nasa.gov/office/pao/History/alsj/a13/AS13-59-8500.jpg) after it was jettisoned. I can only conclude that this was an editing oversight. It happens.

PhantomWolf
2007-Sep-19, 04:14 AM
It doesn't, well unless you made a little (136x102) image that says "bighugelabs.com. Do not direct link to images here. Save a copy instead. Thank you.", which given the context seems somewhat unlikely.

ahhhh, must be a buffer thing, since I can see it, lol. I switch it to my site when I get home.

KaiYeves
2007-Sep-20, 01:05 AM
Even though I've seen the movie a dozen times, at the end, when Gene Kranz signs off and sits down, I always get a tear in my eye.

At splashdown, and just after, when the frogman looks in the window and makes the "thumbs up" sign... :cry:
Even on airplanes.
(Not sure if this counts as a movie goof, but in dive training I was taught to completely phase "thumbs up" out of my mind, as it means "I want to go to the surface" in scuba sign language. Instead they teach you a sign that means "OK". However, I quess that he got caught up in the moment, or maybe scuba signs hadn't been developed in 1970.)
Either way, great movie.

PhantomWolf
2007-Sep-20, 09:19 PM
At splashdown, and just after, when the frogman looks in the window and makes the "thumbs up" sign... :cry:
Even on airplanes.
(Not sure if this counts as a movie goof, but in dive training I was taught to completely phase "thumbs up" out of my mind, as it means "I want to go to the surface" in scuba sign language. Instead they teach you a sign that means "OK". However, I quess that he got caught up in the moment, or maybe scuba signs hadn't been developed in 1970.)
Either way, great movie.

Or perhaps he was communicating with people that wouldn't know their dive signals. ;)

Bolasanibk
2007-Sep-21, 07:49 AM

How cold did it get in the LEM anyway?

I looked around a bit, but didnt find any numbers. and I am not brave enough to go through all those threads of woo.

Bob B.
2007-Sep-21, 01:10 PM
How cold did it get in the LEM anyway?

I don't remember exact figures but I think it fell to somewhere between 32 and 40 degrees F. I believe the CM got colder than the LM but I don't know by how much.

Bob B.
2007-Sep-21, 03:31 PM
It seems the 32°-40° F range may be a little too low. According to this page (http://history.nasa.gov/SP-4029/Apollo_18-39_CModule_Cabin_Temperature_History.htm) the low CM temperature was 58° F, however this measurement is qualified with the following footnote:

"Further examination of Biomedical Results of Apollo reveals that actual cabin temperatures dropped to a low of 43°F. It is likely that the figure in the original text refers to the low cabin temperature while the Command Module was powered up."

And regarding the LM temperature, we're given the following:

"Biomedical Results of Apollo, SP-368, p. 133. All temperatures were measured at the heat exchanger inlet. During the Apollo 13 mission, the LM environmental control system provided a habitable environment for about 83 hours (57:45 to 141:05 GET). Cabin temperature remained low due to low electrical power levels. This caused crew discomfort during much of this period, with cabin temperatures ranging between 49°F and 55 °F."

The reason I thought the temperature reached into the 30s is because a saw an interview with Jim Lovell in which he said there was some freezing of water in the spacecraft. Perhaps there were some cold spots or cold surfaces where this occured.

Dave J
2007-Sep-21, 03:37 PM
From the mission debrief (Haise), it was still "icy cold" with them breathing visible vapor in the CM after splashdown...surprising.

JMV
2007-Sep-21, 04:01 PM
It seems the 32°-40° F range may be a little too low. According to this page (http://history.nasa.gov/SP-4029/Apollo_18-39_CModule_Cabin_Temperature_History.htm) the low CM temperature was 58° F, however this measurement is qualified with the following footnote:

"Further examination of Biomedical Results of Apollo reveals that actual cabin temperatures dropped to a low of 43°F. It is likely that the figure in the original text refers to the low cabin temperature while the Command Module was powered up."

And regarding the LM temperature, we're given the following:

"Biomedical Results of Apollo, SP-368, p. 133. All temperatures were measured at the heat exchanger inlet. During the Apollo 13 mission, the LM environmental control system provided a habitable environment for about 83 hours (57:45 to 141:05 GET). Cabin temperature remained low due to low electrical power levels. This caused crew discomfort during much of this period, with cabin temperatures ranging between 49°F and 55 °F."

The reason I thought the temperature reached into the 30s is because a saw an interview with Jim Lovell in which he said there was some freezing of water in the spacecraft. Perhaps there were some cold spots or cold surfaces where this occured.
Here's the table (http://lsda.jsc.nasa.gov/books/apollo/Resize-jpg/ts6c5-4.jpg) in Biomedical Results of Apollo they were referring to with that 43°F figure. Note the GET 141:15, the time of glycol pump activation; CM power up had been started about an hour earlier, so it's not inconceivable that the temps were somewhat lower than that before CM power up.

There's also this mention in Biomedical Results of Apollo Section VI Chapter 5:

A reported inability by the crew to obtain additional drinking water and a subsequent thermal model analysis indicate that the water tanks, or more probably the water lines in the aft compartment, froze late in the powered down period.

Bolasanibk
2007-Sep-21, 05:35 PM
Damn, that's pretty ... cold.

KaiYeves
2007-Sep-21, 11:19 PM
"Or perhaps he was communicating with people that wouldn't know their dive signals."
I meant that divers are told never to do thumbs up, as it might slip in underwater. But I see your point.

Van Rijn
2007-Sep-21, 11:50 PM
The reason I thought the temperature reached into the 30s is because a saw an interview with Jim Lovell in which he said there was some freezing of water in the spacecraft. Perhaps there were some cold spots or cold surfaces where this occured.

Perhaps the coldplates that normally kept the electronics cool?