The Extraordinary History
of Amateur Radio Satellites

Here's a startling fact — more than 70 Amateur Radio satellites have been launched over four decades. The number is astonishing because these sophisticated and groundbreaking spacecraft are little known outside the ham radio fraternity.

In fact, private groups of Amateur Radio operators around the globe have built and sent dozens and dozens of Amateur Radio communications and science satellites to orbit since the first, OSCAR-1, was launched on December 12, 1961.

The major group involved in space activity is the Radio Amateur Satellite Corporation (AMSAT) headquartered at Washington, D.C. It's membership is composed of volunteer spacecraft designers, builders and operators across America and around the world.

In the beginning. Following the Soviet Union's launch of the first-ever space satellite, Sputnik 1, on October 4, 1957, there was a great deal of interest in the United States in rushing an American satellite to orbit.

At the time, the Jet Propulsion Laboratory (JPL) of the California Institute of Technology, at Pasadena, was a research lab for the U.S. Army. A month after the Sputnik launch, the Army asked JPL to develop a satellite with a science package and communications system. The result was a tiny, 20-lb. spacecraft named Explorer 1.

JPL and the Army Ballistic Missile Agency, at Huntsville, Alabama, blasted the satellite to space on one of the Army's Redstone rockets from the missile test center at Cape Canaveral, Florida, on January 31, 1958. That historic flight of the first U.S. satellite to orbit the Earth launched the nation into the Cold War space race and led to the establishment of the civilian space agency NASA. Today, JPL is a space research center for NASA.

Hams get involved. Amateur radio operators around the world – excited by the beep-beep-beep radio signal they overheard coming down from Sputnik – willing accepted an invitation to tune in Explorer's radio signals. One of the thousands of ham stations searching for signals from space was operated by JPL ham radio operators at the nearby Los Angeles County Sheriff's substation in Temple City, California.      More about    Explorer      Explorer

Some radio amateurs had a bright idea. Hams know all about radio communication. If the government can build a communications satellite, why can't we?

The first amateur radio satellite. A California group of Amateur Radio operators, calling itself Project OSCAR, built the first Amateur Radio satellite in 1961. Since then, the majority of hamsats have been called OSCAR.

Project OSCAR built the first four hamsats. Then AMSAT was founded in 1969. AMSAT's first flight was OSCAR-5 built by Australian students.

All of the high-tech OSCARs have been financed through donations of time, hardware and cash from hams in the United States, Germany, Canada, Great Britain, Australia, Russia, France, Italy, Japan, Brazil, Argentina, Belgium, South Korea, Finland, Israel, Mexico, South Africa, Saudi Arabia, and other nations.

OSCAR. AMSAT satellites are called OSCAR, for Orbital Satellite Carrying Amateur Radio. The number of OSCARs reached a total of 50 satellites in 2002.

Numbers in the OSCAR series are assigned by AMSAT after a satellite has been launched successfully and operated on Amateur Radio frequencies.

For example, two OSCARs launched to space in December 2002 were a German hamsat designated AATiS OSCAR-49 (AO-49) — AATiS is a German group promoting Amateur Radio in schools — and a Saudi Arabian hamsat labeled Saudi OSCAR-50 (SO-50).

Radiosputnik. In addition to the OSCARs, over the years USSR and Russian hams have built and operated 20 separately numbered amateur satellites called Radiosputnik, or RS for short. Three USSR hamsats were called Iskra, which is Russian for "spark."

British Amateur Radio satellites, built at the University of Surrey, have been known as UoSAT. Japanese hamsats have been called Fuji, which is Japanese for "wisteria."

In addition, a handful of Amateur Radio related satellites also have been launched over the years by other groups around the world. The Amateur Radio OSCAR communication and science satellites are not the same as the U.S. Navy series of Oscar navigation satellites. Amateur Radio satellites are referred to informally as hamsats.

Flourishing. The number of Amateur Radio satellites has been mushrooming: Table listing all amateur radio satellite launches »»

What's the difference between amateur radio satellites and amateur-related satellites?

Record launch years were 2000 with nine hamsats launched, followed by 1981 and 1990 with eight hamsats each. Close behind were 1993 and 1998 with five each, and 1991 with four hamsats and eight amateur-related satellites launched. Most hamsats remain in orbit today and many still are in use.

No such thing as a free launch? Over the decades, hamsats often received free rides to space as ballast on U.S., Russian, European and Japanese government rockets that happened to be carrying other commercial or government satellites to orbit. However, with available space over-booked these days, paid tickets usually are required.

Satellite orbits. The major Amateur Radio satellite designs have been labeled Phase-1, Phase-2, and Phase-3: Sky-high repeaters. For the most part, hamsats are communications repeaters in the sky. Their transponders relay voice, Morse code and digital-computer signals. Most amateur satellites today carry gear for digital computer-to-computer communication and store-and-forward message bulletin-board systems (bbs). Sometimes they are science spacecraft with transmitters for radio propagation tests, ionospheric research, radioteletype and meteor sounding; receivers for radioastronomy, radiolocation and other original science research; and television cameras for photos of Earth and space.

Hamsats are open for use by all appropriately-licensed Amateur Radio operators around the world. The satellites serve the public, as well, by training satellite trackers, relaying medical data, teaching school science groups and providing emergency communications for disaster relief.

Beacons. Early amateur satellites carried only one-way radio beacons which sent down telemetry information about conditions of satellite equipment and the space environment to anybody interested in receiving the data. Hamsats of the 21st century still have such beacon transmitters, alongside their high-tech two-way communications transponders.

A hamsat monitors the condition and output of its solar cells and battery. Its telemetry beacon reports the amount of current being generated by the solar cells, the voltage available from the battery, the temperature of the battery, transmitter power, temperatures of other parts of the satellite, and lots of other useful information. Such telemetry data is easily read by amateurs.

Ragchewing. Along with building their spacecraft, hamsat users enjoy an old-fashioned "rag chew" (conversation) via OSCAR. Contests and achievement awards add spice to their time on the air.

Citations awarded to hamsat users can include "Worked All States" for contacting a station in each of the United States via satellite, "Satellite DXCC" for contacting hams in 100 countries via satellite, and a series of technical achievement awards.

Radio amateurs love to track down hidden transmitters in so-called "fox hunts." In a SatFox Test, amateurs at home simulate a hidden transmitter hunt using a hamsat to find a hidden "fox."

A "ZRO Technical Achievement Award" is earned by a hamsat user for superior station performance in a sensitivity test of receiving weak satellite signals.

Weekly Amateur Radio meetings are held on the air. The meetings form a network of operators on the ground and are known as "nets." Participants help each other and spread the latest news of the amateur space program.

Several national organizations support Amateur Radio satellite construction and operation. Among them are:

AMSAT. The Radio Amateur Satellite Corporation (AMSAT) was founded in 1969 as a group of ham operators around the globe who want to build satellites and communicate by satellite. AMSAT groups have constructed and operated numerous OSCARs. ARRL. The American Radio Relay League (ARRL) is the U.S. national Amateur Radio fraternity. Project OSCAR. Project Oscar club is a resurrection in the San Jose, California, area of the original Project Oscar Inc. It is carrying forward the intense interest in amateur radio satellites on behalf of those original members who did so much to make hamsats a reality. The current club members support AMSAT as the North American amateur satellite building organization. Project OSCAR tries to add to the AMSAT effort in any way it can, to further amateur satellite communications and to increase the number of amateurs involved in amateur satellites. TAPR. Tucson Amateur Packet Radio (TAPR) was founded by members of an Arizona chapter of the IEEE Computer Society to develop amateur packet radio, including hamsat systems. Today it is an international organization dedicated to amateur digital communications. Hamsat Chronology.
The 1960s

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