How do you cool a spacesuit in a vacuum?

[myusername]

This has been bugging me all day.

Phase change relies on an external environment to dump the heat energy into. In a vaccuum, the compressor would overheat probably more quickly than the spaceman, right?

You could always carry a finite supply of refrigerant and just evacuate it after the expansion cycle, but what a waste.

Actually, if you were venting to space, you could probably just use water .. but still there would be no reclaiming it. From a cost standpoint, it would probably make sense to look at whatever fluid has the lowest specific gravity.

Chemical reaction would be effective, but like the above would require replenishing from an external source, as well as having a huge gravity bill.

 

[mercanucaribe]

A chemical with a low specific gravity probably also has a low specific heat. I don't know how you cool a space suit.

 

[Powermoloch]

I think NASA had figured that out already...

 

[TitanDiddly]

Spacesuits use much more oxygen than is needed for normal respiratory functions in order to keep the inhabitant cool.

 

[silverpig]

Radiation

 

[myusername]

Originally posted by: Ned
Spacesuits use much more oxygen than is needed for normal respiratory functions in order to keep the inhabitant cool.

I was googling, and it looks to me that the reason for the 100% oxygen is so they can run at lower pressures (so the suits don't balloon up and become bulky and immobile). something like .36 atm. Apparently the Russians run their suits at ~ .56 atm. That would give them the opportunity to throw in some helium, if they were after a cooling effect.

 

[Biggerhammer]

Heinlein's theory was that some waste gas was released from the suit, in part to carry away excess heat. If you're assuming a closed system, your only choices would be heat radiation, stored coolant (dry ice? LN?), or some black box (takes in heat and returns electricity?)

 

[Captante]

In space, unless your right on top of the sun its so cold that radiation should be more the sufficient to dump the heat from a human body, my guess is that staying warm is more of a problem ... a body tempeture (or higher) situation is another question entirely & I unless you expell some gas or liquid as already mentioned I'm not sure how you would do it.

 

[Oscar1613]

space isn't a perfect vacuum

"Near Earth, each cubic centimeter of space ? a volume equivalent to that of a sugar cube ? contains between 100 and 10,000 particles."

 

[SKORPI0]

<a target=_blank class=ftalternatingbarlinklarge href="http://science.howstuffworks.com/space-suit1.htm">The Job of a Spacesuit
</a>

 

[SVT Cobra]

Originally posted by: SKORPI0
<a target=_blank class=ftalternatingbarlinklarge href="http://science.howstuffworks.com/space-suit1.htm">The Job of a Spacesuit
</a>

:thumbsup:

 

[Captante]

Originally posted by: SKORPI0
<a target=_blank class=ftalternatingbarlinklarge href="http://science.howstuffworks.com/space-suit1.htm">The Job of a Spacesuit
</a>

Great read there... very interesting stuff. :beer:

 

[Biggerhammer]

Good find, SKORPIO.

 

[silent tone]

So if it's 120 degrees in the sunlight, why do movies like Apollo 13 portray a ship without life support as freezing when it's not in the shadow of any planet?

 

[InlineFive]

Originally posted by: SKORPI0
<a target=_blank class=ftalternatingbarlinklarge href="http://science.howstuffworks.com/space-suit1.htm">The Job of a Spacesuit
</a>

Very cool. :thumbsup:

 

[brxndxn]

Originally posted by: silent tone
So if it's 120 degrees in the sunlight, why do movies like Apollo 13 portray a ship without life support as freezing when it's not in the shadow of any planet?

Movies are stupid.

 

[Malak]

Originally posted by: brxndxn

Originally posted by: silent tone
So if it's 120 degrees in the sunlight, why do movies like Apollo 13 portray a ship without life support as freezing when it's not in the shadow of any planet?

Movies are stupid.

QFT