In early December 1961, a United States Air Force rocket took off from Vandenberg Air Force Base in California carrying a special payload. The main payload was a Corona surveillance satellite, but tucked just aft of that spacecraft was a tiny package of homebrew electronics stuffed into something the looked like a slice of cake. What was in that package and how it came to tag along on a top-secret military mission is the story of OSCAR 1, the world’s first amateur radio satellite.
The Sputnik Crisis
The late 1950s were a tumultuous time in a lot of ways, but the 1957 launch of Sputnik by the Soviets really kicked things into high gear. In a single day, humanity had been transformed into a space-faring species, a fact anyone could witness just by looking into the sky around sunset as that polished sphere orbited the planet. And you could listen in, too – Sputnik’s 20 and 40 MHz beacons were easily picked up on shortwave sets. Amateur radio operators all over the world tuned to Sputnik’s beacon. In fact, the first re-broadcast of Sputnik’s signal to the general public was courtesy of the Columbia University amateur radio club; members recorded the signal and played the tape over the university’s FM station, beating NBC to the punch.
The “Sputnik Crisis” that ensued was a catalyst for a lot of the changes that led to the world we know today; after all, one of the agencies created to deal with Sputnik was the Advanced Research Projects Agency, or ARPA, which later became DARPA and led to the Internet. But Sputnik also had immediate effects, two of which would combine to make an amateur radio satellite a reality within a few short years. First, Sputnik provided focus for a struggling American space program; beset by a very spectacular series of public failures, Soviet success provided the impetus for the Americans to start getting things right on space delivery systems. And three weeks of listening to the simple shortwave beeps as Sputnik orbited inspired some hams to dream an audacious dream – to build and launch their own satellite.
The Mercedes Man’s Baby
The first glimmers of what was to become Project OSCAR – a somewhat forced acronym for “Orbital Satellite Carrying Amateur Radio” – came in 1959, barely two years after Sputnik. To call the idea audacious is an understatement. Space exploration at the time was the turf of the superpowers; after all, who else would have the resources to put a package into orbit? And so when Don Stoner, a man who would later build his radio shack into the front of a Mercedes, wrote an article that year in CQ Magazine decrying the fact that hams were being left behind in the space race and that they could easily build a satellite if only somebody had a missile handy to launch it, it actually got noticed, and in an atmosphere of “Sputnik fever”, things started happening.
Hams in California started brainstorming about what an amateur radio satellite would look like. While setting a stretch goal of building an orbiting repeater that all hams could access, they also recognized the need for baby steps, and so began designing a simple beacon. Still lacking a delivery vehicle, they stuck to the electronic design and settled on a simple transistorized VHF transmitter. It would be battery-powered to avoid the complexities of solar power, transmitting a simple beacon signal over a monopole antenna. Transmissions would be the classic Morse cypher for laughter, “HI”, sent by an electronic keyer that would vary the speed of the signal based on the temperature of the satellite.
Socially Engineered Launch Vehicle
There aren’t a lot of details out there on how the hams managed to convince the Air Force to let them piggyback onto a mission. The fact that a good number of the OSCAR hams had day jobs in the burgeoning aerospace industry in California was probably a factor, and Stoner himself mentions a 1960 meeting between the would-be satellite builders and the chief of the Space Instrumentation Section at JPL, himself a ham. It would appear that when you want to get a package into orbit, it pays to have connections.
Whatever social engineering went on, the net result was an agreement to piggyback on an upcoming Air Force launch. The satellite was Discoverer 36, a KH-3 Corona surveillance satellite designed to take photographs from orbit and return the film package on a parachute that would be snared by a plane. The amateurs were offered some space in the aft of the payload compartment, space that would normally be occupied by ballast. This set the physical parameters for the satellite, and construction began.
The wedge-shaped body that resulted ended up being only about 10 pounds thanks to its magnesium skin and frame. The builders knew they’d have no attitude control or active systems to manage heat gain, so they settled on passive thermal management. The body was gold-plated to reflect as much incident sunlight as possible. Strips of absorptive paint were then added to the outside to absorb some heat to keep the innards from freezing, and the space inside was filled with foam insulation.
Having been built for a grand total of $63 in parts and now dubbed OSCAR 1, the satellite was tested as best as it could be given an essentially non-existent budget. The build team had to prove that their package not only wouldn’t jeopardize the reconnaissance mission of Discoverer 36, but that they had a decent chance to succeed in their own mission. Airplane flights with a mockup of the satellite were conducted around California, with hams volunteering to monitor the beacon. Procedures were put into place for ground monitoring of the signals. The energy budget of the mercury batteries was tweaked by manipulating the transmitter power, and the thermal characteristics of the spacecraft were analyzed.
Finally, on December 12th, the Thor booster lifted off with OSCAR aboard. Once in orbit, an explosive bolt released, and a spring that had been bought at Sears for a buck ejected the world’s first non-governmental satellite from its mothership. It entered its own orbit and immediately began transmitting its friendly “di-di-di-dit di-dit” greeting to hams the world over. OSCAR 1 worked flawlessly, transmitting for 20 days before the batteries died. A total of 570 hams from 28 countries reported hearing OSCAR 1, which completed about 280 orbits before reentry in late January 1962.
For a minimalist build, OSCAR 1 was hugely successful. Aside from achieving the goal of placing amateur radio in space and proving that civilian groups could cooperate with the military and huge government contractors, OSCAR yielded valuable data, especially on the thermal management system. This was used to improve the thermal design of OSCAR 2, essentially a clone of the first satellite, and eventually OSCAR 3, the first amateur repeater in space. The OSCAR team also invented the concept of launching a sub-satellite from a larger bus and proved that it would work.
The OSCAR project eventually morphed into AMSAT, a volunteer group that has launched a fleet of amateur radio satellites and still runs them today. A small constellation of amateur satellites now orbits the planet, and ham radio is firmly entrenched in space. And it all started with a $63 satellite that was built in a basement by a bunch of hackers who knew what they wanted to accomplish, and found a way to succeed.
[Main image source: National Air and Space Museum]