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Thread: Cooling in space???

  1. #1 Cooling in space??? 
    Forum Sophomore Kabooom's Avatar
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    How does an astronaut, a space shuttle, the space station, or any other space craft stay cool? The sun's rays are constantly beating on them, but yet they're still cool. How can they stay cool if they have no way to radiate the (kinetic)heat? It's in a near-absolute vacuum, the only way to radiate (kinetic)heat would be in IR or some other forum of radiation that works in a vacuum, but I don't see how this works.

    Also if you're in the moon's shadow, why would you cool down? Wouldn't you just stay the same temperature and only slowly loose heat by radiation? Kind of goes with the whole "Is space cold" question, but it's a vacuum so it doesn't have a temperature.


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  3. #2  
    Forum Ph.D. Nevyn's Avatar
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    it's colder in space than it is on earth because they don't have an atmosphear to trap the heat so a space ship has to have heat generaters on board


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  4. #3  
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    HUh?

    You can completely ignore nevyns post...

    The space station cools it's electronics by a form of refrigeration, extrenally is a space 'radiator' always edge on to the sun so as not to gain extra heat. Liquid is pumped around the station and absorbs heat - outside it radiates it. All bodies above 0 kelvin radiate heat energy.

    There are three types of heat transfer, Convect, Conduct and radiate.

    No time to explain further at present, heat cannot travel through a vacuum but EM waves can, when they strike an object they are 'converted' back to heat. (think about the sun warming the earth!).


    And finally, everbody knows astronauts are cool! :wink:
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  5. #4  
    Forum Ph.D. Nevyn's Avatar
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    hmmmm, sorry Kabooom, i am not feeling so good at the moment and i guess i got a little confused :?
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  6. #5  
    Forum Sophomore Kabooom's Avatar
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    I see, I did know about the convection and conduction ways of passing heat, but I didn't notice EM waves were so commonly radiated. Does anyone happen to have a link that shows how much EM materials radiate at what temperatures and such?

    Thanks for the answers.
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  7. #6  
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    Radiation:-

    A body above 0 Kelvin will radiate electromagnetic waves, the frequency of this radiation depends upon the temperature of the body. the amount of radiation depends upon it's surface area.

    An example of EM radiation is the sun, these waves travel through space and upon contacting a mass some of the energy manifests itself as heat.

    Conduction:

    Imagine placing an iron bar into a hot fire, the heat 'travels' alonfg the bar, the heat is conducted.

    Convection:

    'Hot air rises' this is the movement of 'hot material' [gas or liquid] within itself.


    Consider your cup of coffee, as it cools convection currents within the liquid generally move the heat towards the top, this heats the air immediately above causing convection currents also in the air. Heat from the coffee is conducted through the material of the vessel to the outside surface. The outside surface conducts heat into the surrounding air which then causes more convection in the air. The outside surface also radiates heat, which you can feel by placing your hands close to it.
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  8. #7  
    Forum Professor leohopkins's Avatar
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    Yes, and consider a thermos vacuum flask for keeping your drinks warm. It basically stops convection (although not in the liquid itself) it slows down conduction due to the vacuum, although there is a little bit at the top where the two pieces of glass meet each other, though which coduction can occur, although as this is a small area, it acts like a resistor. A vacuum flask, however, will not stop radiation.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  9. #8  
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    Vacuum flasks are coated in a highly (infrared) reflective material, this reflects most of the heat back into the liquid.
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  10. #9  
    Forum Sophomore Kabooom's Avatar
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    Thanks again MB, and I just found out what a vacuum flash was yesterday when doing research on this question. I didn't notice that was how Thermoses worked.

    Is IR radiation really the only form radiation that has to be worried about with most things on Earth? I know there is such thing as cosmic radiation, but I'm thinking on more of a small scale if that makes any sense.

    *EDIT* And also only with non-nuclear/non-lighting objects, as in like a pebble, cup, or anything of the like.
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