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Transit 1B



Navy Transit 1B was the first experimental orbital navigation satellite. It was launched into orbit by a Thor-Able-Star rocket on 13 April 1960 from Cape Canaveral. The payload was the first navigation system experiment ever put into orbit. It also demonstrated the first engine restart in space and the feasiblity of using satellites as navigational aids. Transit spacecraft were developed for updating the inertial navigation systems on board US Navy Polaris submarines, and later for civilian use. The receivers used the known characteristics of the satellites orbit, measured the Doppler shift of the satellites radio signal, and thereby calculated the receiver's position on the Earth. Transit 1B was a 91 cm diameter sphere with a mass of 121 kg. It was powered by body-mounted solar cells and batteries.

Transit 1B was able to provide positional fixes to within 400 meters on the Earth's surface. It was also able to measure the refraction of radio signals caused by the ionosphere. The launch also carried an 18 kg dummy satellite, a small sphere to test the possibility of deploying small "piggyback" payloads into orbit on launches of larger satellites. The concept lead to the subsequent launches of the SOLRAD satellites. Transit 1B began to fail on 11 July 1960.

Image credit: National Museum of the U.S. Navy

Alternate Names

  • 00031
  • 1960 Gamma 2
  • Transit1B

Facts in Brief

Launch Date: 1960-04-13
Launch Vehicle: Thor
Launch Site: Cape Canaveral, United States
Mass: 121 kg

Funding Agency

  • Department of Defense-Department of the Navy (United States)


  • Navigation/Global Positioning

Additional Information

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



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