Please make a donation to support Gunter's Space Page.
Thank you very much for visiting Gunter's Space Page. I hope that this site is useful and informative for you.
If you appreciate the information provided on this site, please consider supporting my work by making a simple and secure donation via PayPal. Please help to run the website and keep everything free of charge. Thank you very much.

Quasar 8, 9, 10, 11 (SDS-2 1, 2, 3, 4)


Satellite Data System (SDS) spacecraft are communication relay satellites for transmiting real-time data from US reconnaissance satellites (e.g. KH-11) 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 KH-11 data to a ground station at Fort Belvoir, Virginia.

Like their SDS predecessors, the most of the SDS-2 spacecraft are in highly elliptical Molniya orbits of 368 × 39700 km at an inclination of 57 to 63, but one (#2) appears to have a geostationary position.

The SDS-2 are reported to carry the HERITAGE infrared early warning system for detection of ballistic missile launches. The inclusion of this package has not been confirmed.

Hughes has continued as the main contractor of the SDS-2 program. The SDS-2 program is operated by the Consolidated Space Test Center.

The Shuttle payload envelope has defined the satellite's design. The SDS-2 features two 15 ft diameter dish antennas and a third dish (6.6 ft in diameter), which serves as a K-band antenna downlink. The SDS-2 has two more antennas, one that is used for uplink communications, and another that is a telemetry and command antenna, which is used as a back-up. The body itself, appears to based on the HS-389 (Intelsat 6) or the HS-381 (Leasat) bus and has likely the designation HS-386.

It was designed to be launched by the Shuttle, although the fourth was launched by a Titan-4(05)A. They probably used an Orbus-21S or a TU-882 kick motor to leave low earth orbit. The SDS-2 cylindrical drop-skirt solar array generates 1,238 Watts of power with support from three 25-amp-hour nickel-cadium batteries.

NRO unveiled in March 1998 photographs, which most probably show the SDS-2 spacecraft. The code-name QUASAR has confirmed by leaked budgets in 2013 to be associated with these satellites.

A sixth satellite was apparently built, but not launched. The bus was donated in March 2017 to NASA as NSTP-Sat (NASA Science/Technology Platform Satellite) for a prurpose to be determined.

Note: The numbering is not sure, as it is not confirmed, how many first generation Quasar were launched.

Nation: USA
Type / Application: Comsat / Relay
Operator: NRO
Contractors: Hughes
Equipment: ?
Configuration: HS-386 ?
Propulsion: ?
Power: Solar cells (body mounted and drop-skirt), batteries
Lifetime: 8 years ?
Mass: ~ 3000 kg ?
Orbit: Molniya Orbit (#8, #10, #11, #12), GEO (#9)
Satellite COSPAR Date LS Launch Vehicle Remarks
Quasar 8 (SDS-2 1, USA 40) 1989-061B 08.08.1989 CCK LC-39B Shuttle [TU-882 ?] with Columbia F8 (STS 28R), USA 41
Quasar 9 (SDS-2 2, USA 67) 1990-097B 15.11.1990 CCK LC-39A Shuttle [TU-882 ?] with Atlantis F7 (STS 38), Prowler 1 (?)
Quasar 10 (SDS-2 3, USA 89) 1992-086B 02.12.1992 CCK LC-39A Shuttle [TU-882 ?] with Discovery F15 (STS 53), ODERACS (A),(B),(C),(D),(E),(F)
Quasar 11 (SDS-2 4, USA 125) 1996-038A 03.07.1996 CC LC-40 Titan-4(05)A [TU-882 ?]
Quasar 12 (SDS-2 5, USA 137, NROL 5) 1998-005A 29.01.1998 CC SLC-36A Atlas-2A
Quasar x (SDS-2 6) - not launched donated to NASA as NSTP-Sat

Cite this page: