|SPACE TODAY ONLINE COVERING SPACE FROM EARTH TO THE EDGE OF THE UNIVERSE|
|COVER||SOLAR SYSTEM||DEEP SPACE||SHUTTLES||STATIONS||ASTRONAUTS||SATELLITES||ROCKETS||HISTORY||GLOBAL LINKS||SEARCH|
Private groups of Amateur Radio operators around the globe have built and sent dozens of Amateur Radio communications and science satellites to orbit since the first, OSCAR-1, was launched on December 12, 1961.
That date already held a special place in radio history. It was the 60th anniversary of the first radio transmission across the Atlantic Ocean. Guglielmo Marconi had completed his famous transmission and reception of Morse code for the letter S -- three dots -- from England to Newfoundland on December 12, 1901.
Here is a summary, in chronological order, of the first four Amateur Radio satellites, launched in the 1960s:
Just four years after the USSR launched the Space Age with its Sputnik artificial satellite, a 10-lb. Orbital Satellite Carrying Amateur Radio, or OSCAR for short, was launched December 12, 1961, as ballast on a Thor-Agena rocket which carried the U.S. military satellite Discoverer-36.
The rocket left OSCAR in an elliptical orbit ranging from 152 to 295 miles above Earth's surface, just above our planet's atmosphere. Known today as OSCAR-1, it was the very first hamsat.
That first tiny 11-lb. hamsat measured 9 in. by 12 in. by 6 in. tall. OSCAR did not offer two-way communications. Its radio only transmitted HI in International Morse code with 140 milliwatts of power on a frequency of 144.983 MHz-fourteen times the power of the 10-milliwatt radio in Explorer-1, America's first satellite.
There was a bit of scientific value in OSCAR's BEEP-BEEP-BEEP-BEEP BEEP-BEEP greeting. The speed of the message was controlled by the temperature inside the satellite.
OSCAR's battery wasn't rechargeable and had only enough strength to power the transmitter for 22 days. During that time, hundreds of amateurs in 28 nations around the globe picked up OSCAR's call from space and mailed in reception reports.
The satellite's low altitude let it stay in orbit above Earth only 50 days. OSCAR slipped down into the atmosphere and burned January 31, 1962.
VINTAGE OSCAR-1 PHOTOS FROM DECEMBER 1961
SOURCE: PROJECT OSCAR INC. AND DON FERGUSON KD6IRE
CLICK AN IMAGE TO ENLARGE LOTS MORE OSCAR-1 PHOTOS »»
The second hamsat was very similar to the first. OSCAR-2 was launched to a 240-mile-high orbit June 2, 1962, just six months after OSCAR-1.
OSCAR-2's transmitter power was lowered to 100 milliwatts to make its battery last longer. However, it operated only 19 days and fell into the atmosphere June 21, 1962.
Another OSCAR, built about the same time with a 250-milliwatt transmitter, wasn't launched.
The third hamsat was the first-ever active telecommunications satellite with free access to all. OSCAR-3 was launched to a 590-mile-high orbit on March 9, 1965. It was the first hamsat to have a two-way signal-repeating transponder making it a radio-relay station in the sky.
OSCAR-3's transponder received signals and used a 1-watt transmitter to repeat those signals. The transponder worked for 18 days in space.
The satellite also had two radio beacons. One sent a continuous signal for tracking and propagation studies. The other sent telemetry data about temperatures and battery voltages.
More than 1,000 hams from 22 nations chatted via OSCAR-3 during its 18 days of operation. The first trans-Atlantic ham satellite link was made. The hamsat also carried the first direct contacts with hams in Eastern European countries such as Bulgaria and the nation known at that time as Czechoslovakia. Other long-distance (DX) contacts linked New Jersey with Spain, Massachusetts with Germany and New York with Alaska.
A few solar cells were attached to the satellite to recharge the battery powering the beacons, thus OSCAR-3 became the first amateur spacecraft to use solar power. However, the satellite was not fully solar powered. The solar cells allowed the beacons to continue transmitting months longer than the transponder. Without electricity, its radios are dead, but the satellite remains in orbit.
More on OSCAR-3: The First Repeater in the Sky
To mark the fourth anniversary of OSCAR-1, the fourth hamsat was launched to orbit December 21, 1965. Unfortunately, OSCAR-4 was the first amateur satellite to have a partial launch failure.
The 30-lb. satellite was blasted into space aboard a Titan 3-C rocket, but the rocket's upper stage failed and the satellite did not make it to its intended 21,000-mi.-high circular orbit. Instead, the satellite ended up in a highly-elliptical orbit ranging from a low point of 122 miles altitude out to 20,875 miles.
OSCAR-4 was the first satellite to be powered fully by solar-cells generating electricity. It also was the first hamsat to use two bands, receiving signals on 144 MHz and transmiting three watts of power on 432 MHz. The first U.S.-to-USSR satellite contact was made through OSCAR-4.
No telemetry beacon was included, so hams were unable to know why OSCAR-4's radio failed after a few weeks. The battery may have overheated or radiation may have knocked out the solar cells.
The radio operated only 85 days. Then, in May 1966, the U.S. worldwide satellite tracking network lost track of Oscar-4, but the small spacecraft was found again April 15, 1972. The satellite stayed in space almost eleven years, falling into the atmosphere April 12, 1976.
Project Oscar was the U.S. West Coast group which designed, constructed and launched the first four OSCARs. In 1969, the Radio Amateur Satellite Corp. (AMSAT) was formed by an East Coast group of amateurs to build and fly hamsats.
Table listing all amateur radio satellite launches »»
The next page continues this interesting story of Amateur Radio satellites with the six hamsats launched in the 1970s:
Satellites Search STO STO cover K3RXK Questions Feedback Suggestions © 2006 Space Today Online