[time-nuts] temperature stability basics

[Bob Camp]

Hi

The gold color in a space thermal blanket is from - gold. The normal formula is to use gold leaf and tissue paper (not quite the Kleenex variety, but similar) in layers. The gold leaf is *very* good for IR reflection. The tissue paper is porous  enough that there's very little air trapped in it. The real insulation is the vacuum (courtesy of mother nature). The gold leaf and the spacer material just take care of the IR part of the equation without adding a lot of conductivity. 

Bob


On Nov 26, 2010, at 5:43 PM, J. Forster wrote:

> That's what those golden thermal blankets are on spacecraft and in
> cryostats. I'm not quite sure whether the golden color comes from a
> deposited film of Au, or whether it's color comes from the Mylar. It's
> more likely the former. I've seen the stuff up close, but have not worked
> wit it personally.
> 
> Anyway, the blankets are made of a mulit-layer sandwich of the film and
> something like spider web as spacers between layers. In vacuum there is no
> convective transfer, the spider spacers reduce conduction, and the
> metalization reduces radiation.
> 
> Best,
> 
> -John
> 
> ============.
> 
> 
>> 
>> namichie at gmail.com said:
>>> Find some closed cell polyethylene that is quite thin and some very
>>> light
>>> aluminium foil and you could make many layers.
>> 
>> How about aluminized Mylar?
>> 
>> If the many-reflective-layers idea really works, I'd expect somebody to
>> sell
>> foam built that way.  Why don't they?
>> 
>> --
>> These are my opinions, not necessarily my employer's.  I hate spam.
>> 
>> 
>> 
>> 
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> 
> 
> 
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