Space Tracking and Surveillance System

The Missile Defense Agency operates the Space Tracking and Surveillance System (STSS), which consists of two satellites in low Earth orbit. These satellites, launched on September 25, 2009, detect visible and infrared light to support the Ballistic Missile Defense System. They are currently functioning from Schriever AFB, Colorado, and are involved in missile defense system testing. The STSS contributes to risk reduction and supports the development of future missile defense space trackers.