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Thread: Covering one's heat signature in space

  1. #1 Covering one's heat signature in space 
    Time Lord
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    There was discussion a few years ago about this. Apparently one problem in science fiction for space battles is that it is almost impossible for any object in space not to be visible to everyone else unless it either

    A)- Is totally cold (down the the level of the CMBR at 2.725 Kelvin)

    or

    B) - Conceals its heat somehow.

    Otherwise everyone else will be able to see the black body radiation it emits. Falling short of being as cold as ambient space, it might be enough to just be cold enough that the majority of the radiation the space ship exists is in a very low frequency range. Then the presence would be detectable but probably the location would be too difficult to pinpoint. The degree to which we can determine the direction light comes from is proportional to the frequency, so at very low frequencies, they would need a huge telescope to determine the exact location of the source.

    http://en.wikipedia.org/wiki/Angular_resolution

    Quote Originally Posted by wiki
    The angular resolution R of a telescope can usually be approximated by


    where

    λ is the wavelength of the observed radiationand
    D is the diameter of the telescope's objective.



    If you know what direction your enemy is watching you from, you could put a small panel between you and them and perhaps cool it (in the process you'd generate more heat, so you'd have to let that heat spill out in the remaining directions.) If your enemy has a lot of eyes in the sky, it's unlikely you'd be able to avoid being seen by more than just a few of them that way.


    I'm not sure, but I'm thinking another possibility would be to do like they do with stealth fighters to give them small radar signatures. Build the surface of the ship out of flat materials so maybe the majority of the emitted heat is getting emitted in directions perpendicular to the flat surfaces (to have a low probability of just so happening to be flat to the exact direction it is observed from). I'm not sure if that actually has any effect on blackbody radiation.

    Black body - Wikipedia, the free encyclopedia

    Any other ideas how to do it? Of course, in faster-than-light sci fi it doesn't really matter how much radiation your ship emits because you'll probably arrive at your target before the radiation arrives anyway.


    Some clocks are only right twice a day, but they are still right when they are right.
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  3. #2  
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    enjoy


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  4. #3  
    Comet Dust Collector Moderator
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    Not applicable to space where the CMBR is 2.75 K
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  5. #4  
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    A heat bath might also work eg using the evaporation of hydrogen from a liquid tank during the space ships operation. Space is full of radiation though so you needn't drop to cryogenic temperatures to be stealth. I'd think the main problem would be from reflected sunlight and the heat you need to get rid of from activity like firing lasers or the operation of sensors/specialist equipment etc.
    At least controlled evaporation could solve one of those. The other might require a nanomaterial with negative refractive index (like the microwave cloaking device but with light).
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  6. #5  
    Forum Radioactive Isotope MagiMaster's Avatar
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    What's with all the necromancy lately? Anyway, this has been discussed at least once or twice since this thread. The short answer is it will never work. The long answer can be found here.
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  7. #6  
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    Coat it with low emissivity materials, particularly in the direction of the observer....some common ones such as Al, and Ag emit less than 5% black body.
    Meteorologist/Naturalist & Retired Soldier
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