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




USA 51 was launched from Cape Canaveral, Florida, using a Delta rocket for the US Department of Defense. Also known as the Low-power Atmospheric Compensation Experiment (LACE), this spacecraft carried visible, infrared and phased sensors to measure distortions in laser beams targeting it from earth. The satellite, built by the Naval Research Laboratory, also carried an ultraviolet plume instrument to determine the best wavelengths to track rocket plumes, and an Army Background Experiment to measure neutron activity in space. Results from experiments aboard this satellite will aid in the design of laser defenses against missile threats. LACE was a gravity gradient stabilized spacecraft with attitude measurement accuracy better than 1 degree. The spacecraft was designed to operate the primary experiment for a 30-month lifetime. It was decommissioned on February 14, 1993.

Alternate Names

  • 20496
  • USA 51
  • Low-power Atmospheric Compensation Experiment

Facts in Brief

Launch Date: 1990-02-14
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States
Mass: 1430 kg

Funding Agency

  • Department of Defense (United States)


  • Surveillance and Other Military

Additional Information

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

[] NASA Logo -