USA-205

USA-205, also known as Space Tracking and Surveillance System Advanced Technology Risk Reduction (STSS-ATRR), and previously as Block 2010 Spacecraft Risk Reduction is a satellite formerly operated by the United States Missile Defense Agency. It was launched to demonstrate new technology for missile detection early warning systems. The technology demonstrated on STSS-ATRR will be used in the development of the Space Tracking and Surveillance System part of the Space-Based Infrared System.

It was launched on a Delta II 7920-10C rocket from Space Launch Complex 2W at the Vandenberg Air Force Base in California, USA at 20:24:25 UTC on 5 May 2009 into a sun-synchronous orbit. The launch was conducted by United Launch Alliance.

Operational and administrative control of the Space Tracking and Surveillance System Advanced Technology Risk Reduction (STSS ATRR) satellite was transferred to Air Force Space Command effective 31 January 2011. In addition to successfully demonstrating required on orbit system performance parameters for a prototype sensor technology, STSS ATRR conducted Space Situational Awareness and related operations on an as-capable basis.