NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header




The spacecraft (SESP 1971-2) was designed to test advanced development payloads. Included in the instrumentation was a celestial mapping infrared scanner to test the closed loop radiator/pump cooler and to gather celestail background radiation. The spacecraft was equipped with a 457-m flexible roll-up solar cell array with multiple delay-retract cycles so that the mechanics of the system and its long-term power generation characteristics could be tested. The spacecraft also tested a command and control system and obtained data on the interaction of energetic particles with the ionosphere. The spacecraft and experiments worked well until 12/20/73 when a command for the transmitter to stop failed and it wore itself out transmitting. The data coverage was 100 percent for the first few months, 50 percent by the end of the first year, and about 2 orbits per week towards the end of the spacecraft life.

Alternate Names

  • SESP 71-2
  • 05560

Facts in Brief

Launch Date: 1971-10-17
Launch Vehicle: Thor
Launch Site: Vandenberg AFB, United States
Mass: 1500 kg

Funding Agency

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


  • Space Physics
  • Astronomy

Additional Information

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



NameRoleOriginal AffiliationE-mail
[] NASA Logo -