[amsat-bb] Re: PEHEUNSAT-1 heard on 2 metres.

[Bob McGwier]

This spacecraft will necessarily be out of service for long periods of 
time and it is to be hoped that during these times the batteries do not 
freeze solid.   The spacecraft mechanical design and thermal design 
contain a few flaws.

The solar panels are on what I will call the +Z side of the spacecraft 
in all the pictures we see, especially those at the AATE site where we 
see launcher close out pictures.  I believe that (SHUDDER) there are 
solar cells only on one face of the spacecraft.   The thing is a flat 
box with horrible asymmetry in the battery placement and a honking 
antenna coming out the side.   But I still believe its principle spin 
axis is perpendicular to this solar array side with the center of mass 
nowhere near the center of the +Z face.  So it will spin like a pancake 
on a pencil but the pencil is nowhere near the center of the pancake.    
There is a large antenna poking out the side and it has unknown mass but 
this will make the spin geometry quite difficult to guess perfectly, but 
nevertheless there will still be long periods during which the principle 
spin axis will be nearly PERPENDICULAR to the satellite-sun vector.   
This means that the panels will receive almost no illumination and one 
can expect the small ampere hour batteries to be discharged quickly and 
also for the VERY large radiating surface (the +Z and -Z) to very 
quickly cool down the inside of the spacecraft to extremely frigid 
temperatures.


The following link is to a wma file which contains a recording of PEHEUNSAT

http://www.human.space.edu/pehuensat.wma

and the following is a link to a FLASH video of the launch:

http://www.ibnlive.com/videos/30805/pslvc7-sucessfully-lifts-off.html


Congratulations to AMSAT-LU and AATE and ISRO for their spacecraft and 
the successful launch.

Enjoy this while it lasts!
73's
Bob
N4HY


-- 
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
(609)-924-4600
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