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Re: Repeater on the Moon

The ALSEP experiments didn't survive more than a few months, and they had a 
SNAP-27 RTG for continuous power during the lunar night -- it's not just a 
matter of powering down, it's surviving thermal cycling that LEO and GTO 
sats don't have to deal with.


Hello Bruce and others.

Just a minor nit if I might.  The ALSEPS were quite long lived.  The last 
lunar landing was Apollo 17 Dec 1972.  The ALSEPS were finally turned off on 
1 Oct 1977.  It was purely an economic measure (the cost was about 2 million 
a year) to help pay for the shuttle.  ALSEPS from Apollo 12,14,15,16,and 17 
were all working pretty good.  There were quirks of course  (off the top of 
my head there was an interesting temperature related problem to one of the 
instruments on 16 or 17) but no serious problems.  The power source was such 
that they would still be working today had they not been turned off.

The trick was the RTG...everything stayed warm because it stayed on.

There is NOT a history of solar power working long on the lunar surface.  
The Apollo 11 instruments were powered by solar arrays and I think (from 
memory) lasted 4 lunar nights.  The Surveyors didnt do much better.  The 
Russian Lunokhod's (there were two) the longest lasted 11 months.

There was some interesting failure mode analysis done of the electronics 
brought back from Surveyor 3 and they all showed failure was "cold" related.

Mars landers have gone about the same route.  The solar powered ones die 
relativly quickly.  Had Viking 1 not been sent a bad command (to point its 
antenna off somewhere) it would in all likely hood probably still be sending 

My guess is that a lunar translator awaits a nuke on the moon.

Robert Oler WB5MZO

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