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USA 205 launch.jpg
Launch of a Delta II rocket carrying an experimental satellite for the Missile Defense Agency's STSS-ATRR.
Mission typeUS military technology demonstration
OperatorMissile Defense Agency
COSPAR ID2009-023A
SATCAT no.34903
Start of mission
Launch date5 May 2009, 20:24:25 (2009-05-05UTC20:24:25Z) UTC
RocketDelta II 7920-10C
Launch siteVandenberg, SLC-2W
Orbital parameters
Reference systemGeocentric
RegimeLow Earth

USA-205,[1] 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.[1] 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.[2]

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.[3]

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.[4]


  1. ^ a b Krebs, Gunter. "STSS-ATRR". Retrieved 2009-04-18.
  2. ^ STSS Risk Reduction Flight Eyes Launch, Aviation Week & Space Technology, April 28, 2009
  3. ^ United Launch Alliance Mission Overview
  4. ^ Missile Defense Agency Space Tracking and Surveillance System Advanced Technology Risk Reduction Satellite transfers to Air Force Space Command, Missile Defense Agency, February 26, 2011, archived from the original on December 2, 2011