AO-7 'Zombie' Satellite Again Enjoying its Time in the Sun:
from The ARRL Letter on August 8, 2013Website: http://www.arrl.org/
"It's baaaaack! Launched November 15, 1974 as the second AMSAT Phase 2 ham satellite, AO-7 http://www.amsat.org/amsat-new/satellites/sat_summary/ao7.php may be the zombie of the Amateur Radio satellite world, having returned from the dead more than a decade ago, then periodically re-emerging. Next year, it will be 40 years old, ancient in satellite years. After its batteries succumbed to old age, AO-7 went silent in 1981, only to spring back to life in 2002, although some believe it may have resurrected itself as much as a year earlier. AMSAT describes the Mode A/B bird as "semi-operational" and "almost certainly" running solely from its solar panels. The ham satellite organization theorizes that AO-7's batteries shorted when they failed, but the short circuit subsequently opened, allowing the satellite to return to life. This means AO-7 only works when it's receiving direct sunlight and shuts down when in eclipse. Since the satellite became undead, terrestrial users have enjoyed numerous contacts via AO-7.
"AO-7 is alive and doing okay," satellite observer Frank Griffin, K4FEG, reported this week. "This season's eclipse cycle has ended." Griffin explained that the eclipse period, during which AO-7 falls silent, lasts about 9 weeks, from mid-spring to mid-summer. According to its operating plan http://ka9q.net/AMSAT-Newsletter-1974.pdf, AO-7 switches to Mode B (70 centimeters up/2 meters down) at 0000 UTC."
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