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Quasar 20, 21 (SDS-4 1, 2)

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: ?
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)
Quasar 21 (SDS-4 2, USA 279, NROL 52) ? 2017-066A 15.10.2017 CC SLC-41 Atlas-5(421)

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