Re: Starlink coating

From: George Roberts via Seesat-l <>
Date: Sun, 19 Jan 2020 22:53:16 -0500
Black is rare on things in space. Vacuum is a good insulator, if 
something is painted black and the sun shines on it, well, it can get 
very hot, 120C is the equilibrium temp for a black insulated plate 
facing the sun. Satellites have to take excess heat seriously and have 
to deal with it.  Painting most things white helps a lot.  White paint 
is "black" in the infrared so it emits well and absorbs less radiation 
from the sun.

If you are going to paint parts of your satellite black you need to 
worry a lot where all that heat will go - how to get rid of it without 
damaging any electronics.

- George

On 1/19/20 8:52 PM, Allen Thomson via Seesat-l wrote:
>> Me too. I vaguely recall long-ago discussions about optically stealthy satellites, in which it was said that no coating would yield sufficient blackness. The approach believed to have been used with Misty and Prowler was to reflect sunlight away from detection threats.
> Yes, that's my understanding also.  Mostly mirrors (for radar as well as optical), plus a bit of absorptive material to fill in some gaps.
>> That said, I wonder whether recent advances using carbon nanotube coatings could be practical for satellite stealth.
> It would be useful to understand whether military optical stealth is more or less demanding than low optical brightness to avoid being annoying to astronomers.
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Received on Sun Jan 19 2020 - 21:53:54 UTC

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