| Name of Satellite, Alternate Names | STSS ATRR (Space Tracking and Surveillance System Advanced Technology Risk Reduction Satellite, USA 205) |
| Country of Operator/Owner | USA |
| Operator/Owner | Missile Defense Agency (MDA) |
| Users | Military |
| Purpose | Technology Development |
| Class of Orbit | LEO |
| Type of Orbit | Sun-Synchronous |
| Longitude of GEO (degrees) | 0 |
| Perigee (km) | 867 |
| Apogee (km) | 879 |
| Eccentricity | 0.000828386027888996 |
| Inclination (degrees) | 98.93 |
| Period (minutes) | 102.41 |
| Launch Mass (kg.) | |
| Dry Mass (kg.) | |
| Power (watts) | |
| Date of Launch | 05-05-2009 |
| Expected Lifetime | |
| Contractor | Northrop Grumman |
| Country of Contractor | USA |
| Launch Site | Vandenberg AFB |
| Launch Vehicle | Delta 2 |
| COSPAR Number | 2009-023A |
| NORAD Number | 34903 |
| Comments | Detect and track missile flights. |