SAMOS (an acronym for Satellite and Missile Observation System) was an early effort by the U.S. Air Force in developing
satellites
for military reconnaissance from space. The
satellites, built by Lockheed Missiles and Space Company, consisted of an instrumented payload attached to the nose of an Agena upper stage used with the Atlas and Thor boosters. The total weight in orbit was 1,860 kg (4,100 lb). The satellites were made primarily of aluminum and were 1.5 m (5 ft) in diameter and 6.7 m (22 ft) long. They had experimental cameras with focal lengths of at least 102 cm (40 in), infrared sensors, telemetry systems, parachute-recovery systems, and equipment for radio transmission of photographs.SAMOS 1,
launched on Oct. 11, 1960, failed to orbit. SAMOS 2 was launched on Jan. 31, 1961, and its transmitters were turned off on Mar. 10, 1961. After the failed launch on Sept. 9, 1961, of SAMOS 3, the project came under the U.S. Air Force's secrecy procedures; further launches were announced but not identified by name. Although the early launches were marred by failures, pictures from SAMOS 2 permitted the U.S. intelligence community for the first time to have a precise count of the number and location of various Soviet missile-launching sites and silos. The technology derived from the SAMOS satellites led directly to the much larger and more versatile Big Bird reconnaissance satellite.