| Name of Satellite, Alternate Names | STSS Demo-1 (Space Tracking and Surveillance System Demonstrator) |
| Country of Operator/Owner | USA |
| Operator/Owner | Missile Defense Agency (MDA) |
| Users | Military |
| Purpose | Technology Development |
| Class of Orbit | LEO |
| Type of Orbit | |
| Longitude of GEO (degrees) | 0 |
| Perigee (km) | 1347 |
| Apogee (km) | 1352 |
| Eccentricity | 0.000323855171967096 |
| Inclination (degrees) | 58 |
| Period (minutes) | 112.68 |
| Launch Mass (kg.) | 2240 |
| Dry Mass (kg.) | 1100 |
| Power (watts) | |
| Date of Launch | 25-09-2009 |
| Expected Lifetime | 2-4 yrs. |
| Contractor | Northrop Grumman |
| Country of Contractor | USA |
| Launch Site | Cape Canaveral |
| Launch Vehicle | Delta 2 |
| COSPAR Number | 2009-052A |
| NORAD Number | 35937 |
| Comments | Use sensors on the two spacecraft to track ballistic missiles. |