AMSAT-OSCAR 7, or AO-7, is the second Phase 2 amateur radio satellite constructed by the Radio Amateur Satellite Corporation (AMSAT). It was launched into Low Earth Orbit on 15 November 1974 and remained operational until a battery failure in 1981. After 21 years of apparent silence, the satellite was heard again on 21 June 2002 – 27 years after launch, and it continues to be used by amateurs daily even now. For a couple of decades, AMSAT has been able to proudly boast that this bird is the oldest operating satellite in space.
However, that record has been challenged. After 47 years of silence, LES-1, a satellite launched by the U.S. Air Force and MIT’s Lincoln Laboratory in 1965, began transmitting again. Its signals were detected by Phil Williams, G3YPQ, from North Cornwall in southwest England on 18 December 2012, verified by other members of the Hearsat group, Flávio A. B. Archangelo, PY2ZX, in Brazil on 22 December 2012, and Matthias Bopp, DD1US, in Germany on 27 December 2012.
According to Williams, LES-1 was determined to be tumbling with a rotation rate of once every four seconds, as determined by distinctive fading of the signals. It is possible that, after 47 years, the batteries failed in a manner that allows them to carry charge directly through to the transmitter on 237 MHz, allowing the satellite to resume transmissions when it is in sunlight. The satellite continues to be operational as tracked by the SatNOGS network.
