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WG3K > ANS 17.11.24 01:22l 18 Lines 2206 Bytes #56 (0) @ AMSAT
BID : ANS322.1
Read: GAST
Subj: AMSAT OSCAR-7 50th Anniversary – A Testbed for Saving Live
Path: DB0FFL<OE2XZR<OE6XPE<DB0ERF<IZ3LSV<I0OJJ<GB7CIP<KA1VSC<WG3K
Sent: 241117/0014Z 10047@WG3K.#SMD.MD.USA.NOAM LinBPQ6.0.24
As we observe AMSAT OSCAR-7â€Ös 50th anniversary as the oldest operating satellite, we should recall what may be its most noteworthy accomplishment.
OSCAR-7 was used to investigate the possibility of locating downed aircraft and disabled sea vessels by using Doppler analysis of signals from emergency location transmitters (ELTâ€Ös).
As envisioned by spacecraft engineers from the United States and Russia, the concept was to relay signals from beacon devices, ELTâ€Ös or emergency location transmitters, already installed on large and small aircraft and on ships and smaller vessels equipped with EPIRBâ€Ös or Emergency Position-Indicating Radiobeacon Stations. These one-way beacon transmitters, originally intended to be received by surface rescue parties, could also be received and transponded by a LEO spacecraft, greatly extending the rescue potential.
[https://www.amsat.org/wordpress/wp-content/uploads/2024/11/Cospas-Sarsat-Log...]
The signals could also be Doppler tracked, one-way, by processing the beacon uplink signal on-board the spacecraft. This would allow the spacecraft to find the source beaconâ€Ös location immediately. This would allow the emergency beacon to be identified and located and the position stored for immediate downlink at the next available ground station. We know it is hard to remember but this was in an era before the creation of GPS!
Scientists from the Russian COSPAS (Russian acronym for “Space System for the Search of Vessels in Distress) and the U.S. SARSAT (Search and Rescue Satellite) teams simulated ELTâ€Ös on amateur radio stations and demonstrated how receiving and relaying ELT transmissions and analyzing Doppler shift as OSCAR-7 passed overhead could accurately locate the emergency beacons.
The tests were highly successful. The COSPAS/SARSAT program went ahead and has been operational since 1982. From that time until 2021, when the program merged with others providing similar capability via LEO, MEO and GEO spacecraft, the program had saved the lives of 57,413 persons in 17,663 separate rescue events, involving downed aircraft and ships at sea.
[ANS thanks Jan King, W3GEY, AMSAT AO-7 Project Manager for the above information]
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