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Transit 3B



The LOFTI satellite configuration consisted of a 25.9-kg aluminum-covered sphere with a diameter of 50.8 cm. It was mounted piggyback on the 113-kg Transit 3B satellite, which was spherical in shape with a 91.4-cm diameter. The two satellites were designed to separate after injection into orbit. The smaller LOFTI was a low-frequency trans-ionospheric satellite that was designed to explore low-frequency radio wave propagation through the ionosphere. The satellite was powered by nickel-cadmium batteries that were charged by six groups of solar cells arranged around the surface of the sphere. The LOFTI contained a telemetry system, a 136.17-MHz transmitter, a command receiver, and two VLF receivers for 18-KHz signals from a VLF transmitter (NBA) in the Panama Canal zone. The transit 3B satellite was powered by nickel-cadmium batteries charged by 6600 solar cells. It contained instruments for advanced development of an all-weather global navigation system for surface craft, submarines, and aircraft. Transit 3B contained two transmitting systems, a command system, a despin system, and electronic clock, a telemetry system, and a digital memory system for storing orbital data from ground stations to compute an accurate navigational fix. A SECOR (SEquential COllation of Range) transponder was carried as part of a new geodetic survey system. The two satellites failed to separate owing to a programmer malfunction during launch. The orbit was more elliptical than the planned circular orbit, which shortened the satellite's lifetime to 37 days. Satellite transmitters functioned normally, and signals were received although the elliptical orbit decreased the value of the data.

Alternate Names

  • LOFTI 1
  • 1961 Eta 1
  • 00087
  • Transit3B

Facts in Brief

Launch Date: 1961-02-22
Launch Vehicle: Thor
Launch Site: Cape Canaveral, United States
Mass: 600 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: Coordinated Request and User Support Office

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