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OSCAR (Orbiting Satellite Carrying Amateur Radio) 1 was a privately built satellite designed to send a continuous signal from Earth orbit to be picked up by amateur radio operators across the globe. It was built by volunteer effort of a group of amateur radio operators. OSCAR 1 was the first non-governmental satellite to be launched, and the first satellite launched as a secondary payload and deployed into a separate orbit from the primary satellite. It was the first of what was to become a long series of OSCAR satellites.

Spacecraft and subsystems

OSCAR 1 was a quasi rectangular box, about 30 x 25 x 12 cm, primarily made of magnesium, with a mass of approximately 5 kg. The two approximately square surfaces were slightly curved, but were concentric with each other. One was slightly smaller than the other. 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. It contained a radio transmitter and a keying circuit, which would generate and transmit the word "hi" in morse code. There was also a pair of thermistors and a timer. The timer was connected to the thermistors to control the pace at which the "hi" signal was sent out based on the temperature. Power was provided by three 18V batteries wired in parallel. The interior of the spacecraft was filled with a foam-like substance to protect the components. There was no propulsion or attitude control system on the satellite.

Mission Profile

OSCAR 1 launched on 12 December 1961 at 20:38 UT from Vandenberg Air Force Base. It was a secondary satellite on the Discoverer 36 mission, stored near the bottom of the Thor-Agena launch vehicle. After reaching orbit, OSCAR 1 was jettisoned, using explosive squibs and springs, into a 245 x 474 km altitude orbit with an inclination of 81.2 degrees. The antenna was released by a spring switch. A second spring switch started power to the components. The spacecraft operated for about 20 days, sending out a continuous "hi" message in morse code, received by radio operators in 28 different countries.

Image credit National Air and Space Museum

Alternate Names

  • 00214
  • 1961 Alpha Kappa 2
  • OSCAR1

Facts in Brief

Launch Date: 1961-12-12
Launch Vehicle: Thor-Agena
Launch Site: Vandenberg AFB, United States
Mass: 5 kg

Funding Agencies

  • Project Oscar Inc (United States)
  • Department of Defense-Department of the Air Force (United States)


  • Communications

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Perry I. KleinGeneral ContactAMSAT
Mr. ProjoscarProject ManagerFoothills College
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