Satellite Data System (SDS) spacecraft are communication relay satellites for transmiting real-time data from US reconnaissance satellites (e.g. KH-12) in polar areas. They are also used for communications to USAF air craft on polar routes and connect the various ground stations of the Air Force Satellite Control Network (AFSCN). The spacecraft relay the downlinked data to a ground station at Fort Belvoir, Virginia.
These satellites are the third generation of the system, the SDS-3. Four of them (#1, #4, #5) are in highly elliptical Molniya orbits, but the other two (#2, 3) appears to have a geostationary position. Unlike the Trumpet Follow On Elint satellites, the SDS-3 satellites are not placed directly into the Molniya orbit, but use a lower apogee transfer orbit.
The code-name QUASAR has been suspected to be associated with these satellites.
The SDS-3 operating in highly elliptical Molniya-orbits are reported to carry the HERITAGE (Radiant Agate) infrared early warning system for detection of ballistic missile launches. The inclusion of this package has not been confirmed.
| Nation: | USA |
|---|---|
| Type / Application: | Comsat / Relay, early warning |
| Operator: | USAF |
| Contractors: | ? |
| Equipment: | ? |
| Configuration: | ? |
| Propulsion: | ? |
| Lifetime: | |
| Mass: | ? |
| Orbit: | Molniya Orbit (#1, #4, #5), GEO (#2, #3) |
| Satellite | Date | LS | Launcher | Remarks: | |
|---|---|---|---|---|---|
| SDS-3 1 ? (USA 137) | 29.01.1998 | CC SLC-36A | Atlas-2A | ||
| SDS-3 2 ? (USA 155) | 06.12.2000 | CC SLC-36A | Atlas-2AS | ||
| SDS-3 3 ? (USA 162) | 11.10.2001 | CC SLC-36B | Atlas-2AS | ||
| SDS-3 4 ? (USA 179, NROL 1) | 31.08.2004 | CC SLC-36A | Atlas-2AS | ||
| SDS-3 5 ? (USA 198, NROL 24) | 10.12.2007 | CC SLC-41 | Atlas-5(401) |
| Further SDS missions: |
Last update: 27.09.2009
Contact: gunter.krebs@skyrocket.de
© Gunter Dirk Krebs