[amsat-bb] Re: PEHEUNSAT-1 heard on 2 metres.
n4hy at idaccr.org
Tue Jan 16 08:55:50 PST 2007
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
The following link is to a wma file which contains a recording of PEHEUNSAT
and the following is a link to a FLASH video of the launch:
Congratulations to AMSAT-LU and AATE and ISRO for their spacecraft and
the successful launch.
Enjoy this while it lasts!
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
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