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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:
- Only four were orbited in all of the 1960s.
- Six went to space in the 1970s.
- Seventeen amateur radio and amateur-related satellites were launched in the 1980s.
- Two dozen amateur radio and amateur-related satellites were launched in the 1990s.
- More than a dozen have been launched since the turn of the century.
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:
- Most hamsats have been Phase-1 and Phase-2. They fly in north-south polar orbits or low east-west equatorial orbits from 200-1,000 miles altitude. By comparison, that's about where a space shuttle usually flies or a bit higher. Such a low-flying hamsat circles the globe, coming within range of a ham station on the ground every hour or so. It stays overhead only 15 to 30 minutes. Polar-orbit satellites come within range of a ground station about the same time every day. These are Low Earth Orbit (LEO) satellites. The original Phase-1 satellites had severely limited electrical power and could last only a few weeks. Phase-2 hamsats work longer and communicate over distances up to 4,000 miles.
- Entering the 1980s, AMSAT envisioned larger amateur satellites in long elliptical orbits that would keep them in view of ground stations for hours at a time. These Phase-3 hamsats would be more complex and use higher radio frequencies. Phase-3 satellites could provide communication over longer distances because of their higher altitudes. These high-fliers would range out 20,000-30,000 miles from Earth, then loop back around the planet, dropping to within 1,500-2,500 miles of the surface every ten to twelve hours. Such long elliptical tracks are known as Molniya orbits after a class of Russian communications satellites which followed similar paths through space.
- If there ever were to be a Phase-4 hamsat, it would be an OSCAR in a stationary orbit some 22,300 miles above Earth. It would appear to stay over the same area of the globe. However, there won't be any of those for a while.
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.
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Address: AMSAT, P.O. Box 27, Washington, D.C. 20044
www.amsat.org
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Address: ARRL, 225 Main Street, Newington, Connecticut 06111
www.arrl.org
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www.projectoscar.net
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Address: TAPR, 8987-309 E. Tanque Verde Rd., #337, Tucson, AZ 85749-9399
www.tapr.org
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What follows is the interesting and exciting four-decade history of Amateur Radio satellites:
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