Satellite Data System (SDS) spacecraft are communication relay satellites for transmitting real-time data from US reconnaissance satellites (e.g. KH-11) in polar areas. They are also used for communications to USAF aircraft 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 fourth generation of the system, the SDS-4.
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.
|Type / Application:||Comsat / Relay|
|Quasar 20 (SDS-4 1, USA 269, NROL 61) ?||2016-047A||28.07.2016||CC SLC-41||Atlas-5(421)|
|Quasar 21 (SDS-4 2, NROL 52) ?||-||2018||CC SLC-41||Atlas-5(421)|