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OSCAR 1, 2



OSCAR 1 (Orbiting Satellite Carrying Amateur Radio 1) was the first radio amateur satellite.

It was a curved quasi rectangular box, about 30 × 25 × 12 cm. The two approximately square surfaces were slightly curved, but were concentric with each other. One was slightly smaller than the other. The shape was determined by the shape of some ballast carried on the Agena-B upper stage, which provided the space to carry the satellite. A monopole transmitting antenna about 60 cm long extended from the center of the convex surface of the larger square. Reflective striping was applied for temperature control. This satellite was made by volunteer effort of a group of amateur radio operators and was launched as ballast on an AF launch vehicle. The spacecraft was battery operated and had no attitude control system.

The first OSCAR Phase I amateur satellite was launched piggyback with KH-3 5 (Discoverer 36). A group of enthusiasts in California formed Project OSCAR and persuaded the United States Air Force to replace ballast on the Agena upper stage with the 4.5 kg OSCAR I package. The satellite was box shaped with a single monopole antenna and battery powered. The 140 mW transmitter onboard discharged its batteries after three weeks. 570 Amateurs in 28 countries reported receiving its simple 'HI-HI' morse code signals on the VHF 2 meter band (144.983 MHz) until 1 January 1962. The speed of the HI-HI message was controlled by a temperature sensor inside the spacecraft. OSCAR I re-entered the atmosphere 31 January 1962 after 312 revolutions.

OSCAR 2 was a nearly identical copy of the first satellite. Differences included changing the surface thermal coatings to achieve a cooler internal spacecraft environment, modifying the sensing system so the satellite temperature could be measured accurately as the batteries decayed, and lowering the transmitter power output to 100 mW to extend the life of the onboard battery. OSCAR II was launched piggy back with KH-4 5 and lasted 18 days ceasing operation on 20 June 1962 and re-entered 21 June 1962.

A third OSCAR was designed, built, and tested, but was never launched. Similar in design to OSCAR 1 and 2, OSCAR* contained a 250 mW beacon with phase-coherent keying. OSCAR* was never launched as the workers decided to focus their efforts on the first relay satellite - OSCAR 3.

Nation: USA
Type / Application: Amateur radio communication
Operator: Project OSCAR
Contractors: Project OSCAR
Propulsion: None
Power: Batteries
Lifetime: 20 days (#1); 18 days (#2)
Mass: 5 kg (#1); 10 kg (#2)
Orbit: 372 km × 211 km, 81.2 (#1); 384 km × 206 km, 74.2 (#2)
Satellite COSPAR Date LS Launch Vehicle Remarks
OSCAR 1 1961 ακ 2 12.12.1961 Va 75-3-4 Thor-DM21 Agena-B with KH-3 5
OSCAR 2 1962 χ 2 02.06.1962 Va 75-3-4 Thor-DM21 Agena-B with KH-4 5
OSCAR* - not launched

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