MiTEx

The Micro-satellite Technology Experiment (MiTEx) is a microsatellite-based mission launched into geosynchronous orbit on June 21, 2006, aboard a Delta II rocket. The US Air Force described the mission as a "technology demonstration" for the Defense Advanced Research Projects Agency (DARPA), the U.S. Air Force, and the U.S. Navy. MiTEx consists of three spacecraft; two inspection satellites, designated USA-187 and USA-188, and an experimental upper stage, designated USA-189. The two inspection satellites were initially used to inspect each other; however, they were later used to inspect DSP-23, a failed missile detection satellite, to find out why it stopped operating.