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 satellite.
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 Canada). 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: [email protected] [mailto:[email protected]] On Behalf Of Bob- W7LRD Sent: Friday, June 13, 2014 6:40 PM To: [email protected] Subject: [amsat-bb] AO-7 At 2231Z AO-7 downlink quit. In full sun, any ideas? 73 Bob W7LRD _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
