Modern technology gives us many things.

Retrotechtacular: The OSCAR 7 Satellite Died And Was Reborn 20 Years Later

If I have to ask you which is the oldest artificial orbital satellite still in use, I expect to hear different answers. Space geeks may mention passive radar calibration spheres or possibly some of the early meteorological satellites. But what about the oldest communication is the satellite still in use?

The answer is complex. Oscar 7 is an amateur radio satellite, launched on November 5, 1974, carrying two transponders and four beacons, all of which operate in bands accessible to amateur radio operators. Almost 45 years later, it still provides radio amateurs with contacts, just as it did in the 1970s. But the story of this bird is anything but ordinary. This is the companion who returned from the dead after being considered lost forever. And just as he was disappearing from sight, he played an unexpected role in the resistance against the communist government in Poland.

Built to last only 3 years

OSCAR 7 is preparing for a vibration test before launch.  (AMSAT)
OSCAR 7 is preparing for a vibration test before launch. (AMSAT)

Since its launch, OSCAR 7 has had a life expectancy of three years. This is not uncommon, these estimates tend to be conservative and fortunately he continued to work after this period of time.

During his initial life, he achieved several first amateur radio satellites, including the first amateur intersatellite relay between him and OSCAR 6. Eventually, in June 1981, he failed periodically and was abandoned by the amateur radio community, its beacons, and two transponders are considered silent forever, just like those from previous OSCAR vessels.

However, all was not lost, as in July 2002 it was heard once more by [G4CUO] in the United Kingdom. It had accomplished the impossible and returned from the dead, and too long ago the amateur radio community had used it again for contacts.

Very, very dead battery

The resurrected OSCAR 7 can only work when bathed in sunlight. The design included batteries to cover full orbit, which almost 30 years after the launch apparently no longer worked. The battery pack is thought to have caused the satellite’s initial failure when it developed a short circuit that drained the vessel’s power supply. After two decades less of space debris, the battery further degraded to the point that it became an open circuit. By effectively removing damage from the system, transponders could receive energy directly from solar panels as long as the sun can reach them.

OSCAR 7 came back to life and I remember the surprise in the community at that time. There were no other satellites missing at the time, but the return of a long-dead satellite was definitely something of a special event.

Polish Communist leader Wojciech Jaruzelski declares martial law.  Warsaw, 13 December 1981 [Public Domain]
Polish Communist leader Wojciech Jaruzelski has declared martial law. Warsaw, 13 December 1981 [Public Domain]

So the amateur radio community built a satellite, lost it, and miraculously regained it. It’s a nice story, but it’s not whole history of OSCAR 7.

When these batteries were damaged in 1981, the satellite did not go out as a light, but continued to operate periodically. As radio amateurs switched to a newer vessel, people deprived of unlimited communication took advantage of the opportunity to use an unattended satellite – even one that was defective. The solidarity movement in Poland was constrained by the government ‘s restriction of communications and uses the satellite to transmit messages internationally and between Polish cities (Polish language, Link to Google Translate.) to assist in the coordination of their activities.

The highly focused nature of the antennas needed to access an amateur radio satellite makes them extremely difficult to detect. OSCAR 7 presented the unthinkable: a relatively secure satellite communication system at no cost.

So, if you’re ever wondering why amateur radio is appropriate or still expanding, consider OSCAR 7. One of the oldest spaceships still in use, which has played a role in world history. The best part is that you can use it yourself for the effort of obtaining an amateur radio license.

Comments are closed.