The Missile Defense Agency, supported by NASA and the commercial firm United Launch Alliance, successfully launched the Space Tracking and Surveillance System (STSS) Advanced Technology Risk Reduction (ATRR) satellite from Vandenberg Air Force Base, California, at approximately 1:24 p.m. PDT (4:24 p.m. EDT). The satellite was launched aboard a Delta II 7920-10 launch vehicle. MDA, the U.S. Air Force Space and Missile Center Space Development and Test Wing, and NASA have overall mission management responsibility. Air Force officials say the satellite achieved low Earth orbit about an hour after launch.

STSS ATRR is a small experimental satellite that serves as a pathfinder for next-generation sensor technology for future MDA space missions. The program takes multiple approaches to reduce overall risk to the layered Ballistic Missile Defense System (BMDS) through sensor testing, launch and space vehicle integration, resource protection and security planning, and launch site processing.

Rick Lehner, a spokesman for the Missile Defense Agency, says the satellite is equipped with experimental sensors designed to detect, track and provide targeting information on missiles. MDA is pursuing a space-based sensor layer to detect missile launches, provide continuous target tracking, and pass track data to missile defense interceptors with the accuracy and timeliness necessary to enable successful target interception. Two developmental STSS demonstration satellites will also be launched aboard a single launch vehicle late this summer from Cape Canaveral, Florida.

The BMDS space sensor layer will provide combatant commanders with the ability to continuously track strategic and tactical ballistic missiles from launch through termination. Early launch detection and continuous midcourse tracking of target missiles will significantly improve the engagement time and effective defended area of the BMDS.