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SAMOS 1 was the first in the series of Satellite and Missile Observation Satellites (SAMOS) launched by the US Air Force from Vandenberg Air Force Base aboard an Atlas Agena-A rocket. It was a first generation photo surveillance satellite intended to radio relay images back to Earth but loss of nitrogen gas pressure disrupted the guidance and control systems, causing a second stage failure. No data were returned.

The major objective of the SAMOS 1 mission was to determine the engineering feasibility of obtaining ground observation capability from an orbiting satellite. It launched on 11 October 1960 at 20:34 UT from the Pacific Missile Range in Point Arguello, California. The first stage separated at 249.9 seconds after liftoff. The Agena second stage ignited at 506.7 seconds and cutoff at 629.3 seconds, as planned, but a loss of nitrogen gas pressure had disrupted the guidance and control systems at 123 seconds, resulting in poor trajectory and failure to orbit the payload. Tracking telemetry were lost prior to the Agena ignition, so the exact trajectory was unknown.

The payload comprised photographic and related test equipment, telemetry, radiation, tracking, and command instrumentation. The payload was housed in the Agena second stage. The entire stage was designed to go into orbit. The stage, including payload and casing, had a planned orbital mass of 1845 kg. It was a 6.7 meter (22 ft.) high, 1.5 meter (5 ft.) diameter cylinder. The first stage was a modified Atlas ICBM. The full rocket was 30.2 m (99 ft.) high with a base diameter of 3.05 m (10 ft.) and a liftoff mass of approximately 124,000 kg.

Facts in Brief

Launch Date: 1960-10-11
Launch Vehicle: Atlas-Agena
Launch Site: Point Arguello, United States
Mass: 1845.0 kg

Funding Agency

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


  • Surveillance and Other Military
  • Space Physics

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David R. Williams.

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