The U.S. Missile Defense Agency (MDA) has completed its demonstration program with a classified experimental missile tracking satellite and will transition it to the control of Air Force Space Command to support the service’s space situational awareness mission, according to a Nov. 8 MDA press release.

The Space Tracking and Surveillance System (STSS) Advanced Technology Risk Reduction satellite, built by Northrop Grumman Aerospace Systems of Los Angeles, was launched in May 2009. Northrop Grumman also built a pair of unclassified STSS demonstration satellites that were launched four months later; all three spacecraft are precursors to an operational missile tracking constellation planned by the MDA.

The classified STSS satellite has demonstrated the required on-orbit system capabilities, and has also been performing space situational awareness functions, the press release said.