On Wed, Dec 21, 2005 at 12:39:01PM -0000, Alan B. Pearce wrote:
> >How about a 2-sided Mirror on the clock mechanism
> >reflecting the beam from a stationary laser, so it
> >gives a 180 deg sweep for each 12 hour period
> >(clock mech driven at half speed to give 1 rotation
> >every 24 hrs)
> 
> hey we do that on our space craft instrument to scan the earth each rotation
> of the craft.
> 
> Next one being launched tonight 22:33GMT. Details at
> http://www.sstd.rl.ac.uk/ under "launches and events" "MSG2".

Thanks for the link! Interesting work, nice "big-money" looking
pictures, compared to the stuff I do.

One question... I noticed that you mention that the survival heaters are
turned on before launch keeping the temperature at 17C or so. These
heaters seem pretty common in craft that I've seen to keep the
electronics from freezing up. What I'm interested in is how much of the
power budget gets used for that kind of thing? I assume less so then you
might think, given that in space all cooling has to happen by radiation,
am I right?

Keeping my parents house at 17C up in -45C far-north Yellowknife, Canada
is hard enough with a 3000 litres of oil in a nice tank! Let alone
trying to do it in space with solar power.

-- 
pete@petertodd.ca http://www.petertodd.ca
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