[amsat-bb] AO-7

Andrew Glasbrenner glasbrenner at mindspring.com
Fri Jun 13 23:04:23 UTC 2014

I have a theory, and it's just a theory based on my time managing AO-51, and
looking at several of the older available publications that describe the

AO-7 is barrel shaped, with solar panels around the outside of the barrel
(really an octagonal column shape). The top and bottom ends do not have
solar cells or panels. (AO-51 had panels on each Z end, but only half the
number of cells as the sides.) AO-7 is also magnetically stabilized, where
the bottom flat end and the VHF/UHF antenna array of the satellite points
towards magnetic north when in vicinity of the north magnetic pole (Northern

If you look at the position of the sun, AO-7 and north magnetic polar during
most of the reported failures, the satellite is in a position where the sun
is shining down on the top, and only partially illuminating the panels on
the side, and at a very low (poor) angle. In this attitude, the power
generated drops, and the reset occurs, especially in the presence of strong
user signals.

There are other factors, including just the ageing of the solar cells
leading to a reduction in power generated, precession of the orbit, and
probably others.

Just food for thought.

73, Drew KO4MA

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Bob- W7LRD
Sent: Friday, June 13, 2014 6:40 PM
To: amsat-bb at amsat.org
Subject: [amsat-bb] AO-7

At 2231Z AO-7 downlink quit. In full sun, any ideas? 
73 Bob W7LRD 
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