Satellite Data System (SDS) spacecraft are communication relay satellites for transmitting real-time data from US reconnaissance satellites (e.g. KH-11, Onyx, Topaz). They are also used for communications to USAF aircraft 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 fourth generation of the system, the SDS-4, which appears to use only the geostationary orbit and no longer the highly elliptical Molniya orbits of the earlier generations.
The code-name QUASAR has been confirmed by leaked budgets in 2013 to be associated with these satellites.
Note: The numbering is not sure, as it is not confirmed, how many first generation Quasar were launched.
Note: The NROL designations refer to the launch, not to the payload.
| Nation: | USA |
|---|---|
| Type / Application: | Comsat / Relay |
| Operator: | NRO |
| Contractors: | ? |
| Equipment: | ? |
| Configuration: | ? |
| Propulsion: | ? |
| Power: | |
| Lifetime: | |
| Mass: | |
| Orbit: | GEO |
| Satellite | COSPAR | Date | LS | Launch Vehicle | Remarks | |
|---|---|---|---|---|---|---|
| Quasar 20 (SDS-4 1, USA 269, NROL 61) ? | 2016-047A | 28.07.2016 | CC SLC-41 | Atlas-5(421)¹ | ||
| Quasar 21 (SDS-4 2, USA 279, NROL 52) ? | 2017-066A | 15.10.2017 | CC SLC-41 | Atlas-5(421)¹ |
