[time-nuts] Temperature sensors and bridge amps

jimlux jimlux at earthlink.net
Tue Nov 16 00:41:30 EST 2010


Bill Hawkins wrote:
> Harry,
> 
> What's the ambient temperature swing for the outer oven in space? 
> 
> Bill Hawkins
> 

That would depend (a lot) on the thermal design of the spacecraft.  We 
typically design for a temperature range of -20C to +70C, but we don't 
expect to see anywhere near that sort of variation on orbit.  That range 
is more to make sure it works every time.

A piece of equipment on a typical LEO satellite might see 5-10 degree 
variations in temperature at the baseplate during the 100 minute 
revolution, depending on where the orbit is relative to the sun (if you 
go in and out of eclipse, the variations are bigger).  A lot of 
satellites have smaller variations on a hour to hour basis, but might 
have a 5-10 degree change over the seasons.

Radios on Mars rovers and the like see pretty big temperature 
fluctuations between night and day (many tens of degrees C), although, 
again, specifics of design make a difference.  For instance, if you've 
got enough battery, you can run heaters during the night. 
RHU(Radioactive Heating Units) help limit the minimum temperature.

On deep space, the temperature fluctuations are very small.. solar 
loading is pretty constant, attitude is usually kept the same, etc. The 
changes are when different instruments are turned on and off, or if you 
change attitude to point a sensor somewhere.




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