SDS satellites

Description:

• The Satellite Data System (SDS) is a system of United States military communications satellites. At least three generations have been used:
  SDS-1 from 1976 to 1987; SDS-2 from 1989 to 1996; SDS-3 from 1998 to the present.
  SDS satellites have a highly elliptical orbit, going from about 300 kilometers at perigee to roughly 39,000 km at apogee in order to allow communications with polar stations that cannot contact geosynchronous satellites. The high apogee meant that the polar regions were visible for long amounts of time, and only two satellites were required in order to achieve constant communications ability. In addition, two geostationary satellites appear to be part of the system. The SDS satellites were constructed by Hughes Aircraft.
• The primary purpose of the SDS satellites is to relay imagery from low-flying reconnaissance satellites, notably the Keyhole optic reconnaissance and Lacrosse/Onyx radar reconnaissance satellites to ground stations in the United States.
• Each SDS-1 satellite had 12 channels available for ultra-high frequency communication. They were cylindrical in shape, roughly 25 feet (7.6 m) long. 980 watts of electrical power were available from solar panels and batteries. The SDS-1 had a mass of 1385 pounds (630 kilograms) and was launched on Titan-3B rockets. The SDS-1 satellites had similar orbits to the Air Force's Jumpseat ELINT satellites.
• The SDS-2 is significantly more massive at 5150 pounds (2335 kg), with three separate communication dishes, including one for a K band downlink. Two dishes are 15 feet (4.5 meters) in diameter, while the third is 6.6 feet (2 m) in diameter. The solar arrays generate 1238 watts of power. It is believed that the Space Shuttle has been used to launch several satellites, possibly on missions STS-28, STS-38, and STS-53. Other launches have used the Titan-4 rocket.
• The third generation of the system are the SDS-3. Some of them (#12, #15, #16) are in highly elliptical Molniya orbits, but the other (#13, #14, #17, #18) have a geostationary position. #19 will also be launched into a geostationary orbit. 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 SDS 3-4 satellite (USA 179, 2004-034A) created a tiny trail perpendicular to the star trails in this 10 second exposure with a Zeiss Sonnar MC 2.8/180mm lens made by amateur satellite observer Marco Langbroek
• Quasar is the rumored code name for the communications satellite.
  The code-name QUASAR has confirmed by leaked budgets in 2013 to be associated with these satellites.
  There are reports, that the satellites launched from 2011 onwards might represent a fourth generation.

Launches:

SDS-1:

    * SDS F-1 launched 02 Jun 1976 1976-050A (OPS-7837) (Quasar 1)
    * SDS F-2 launched 06 Aug 1976 1976-080A (OPS-7940) (Quasar 2)
    * SDS F-3 launched 05 Aug 1978 1978-075A (OPS-7310) (Quasar 3)
    * SDS F-4 launched 24 Apr 1981 1981-038A (OPS-7225) (Quasar 4)
    * SDS F-5A launched 28 Aug 1984 1984-091A (USA-4) (Quasar 5)
    * USA-9 launched 08 Feb 1985 1985-014A (USA-9) (Quasar 6)
    * SDS F-6 launched 12 Feb 1987 1987-015A (USA-21) (Quasar 7)

SDS-2:

    * USA-40 launched 08 Aug 1989 on STS-28 1989-061B (USA-40) (Quasar 8)
    * USA-67 launched 15 Nov 1990 on STS-38 1990-097B)(USA-67) (Quasar 9)
    * USA-89 launched 02 Dec 1992 on STS-53 1992-086B (USA-89) (Quasar 10)
    * USA-125 launched by Titan IV 03 Jul 1996 1996-038A (USA-125) (Quasar 11)

SDS-3:

    * USA-137 Capricorn launched by Atlas IIA 29 Jan 1998 1998-005A (Quasar 12)
    * USA-155 Great Bear launched by Atlas IIAS 06 Dec 2000 2000-080A (Quasar 13)
    * USA-162 Aquilla launched by Atlas IIAS 11 Nov 2001 2001-046A (Quasar 14)
    * USA-179 Nemesis launched by Atlas IIAS 31 Aug 2004 2004-034A (Quasar 15)
    * USA-198 Scorpius launched by Atlas V 401 10 Dec 2007 2007-060A (Quasar 16)
    * USA-227 launched by Delta-4M 11 Mar 2011 2011-011A (Quasar 17)
    * USA-236 launched by Atlas-5(401) 20 June 2011-2 2012-033A (Quasar 18)
    * USA-252 Quasar 19 launched by Atlas-5(401) 22 May 2014 2014-027A (Quasar 19)

USA 155 and USA 162 are geostationary satellites.

External resources

• The first generation SDS satellites were launched by Titan 34B/Agena D rockets and deployed directly into 12-hour orbits. These were highly elliptical NRO signals itelligense missions (First generation, n° 5-7)

     Flight Designation Date         LV                  Orbit km x km x deg
         [First generation]
     1      -           1971 Mar 21  Titan 23B/Agena     328 x 39264 x 63.2
     2      -           1972 Feb 16  Titan 23B/Agena     Failed to orbit
     3      -           1973 Aug 21  Titan 23B/Agena     392 x 39132 x 63.3
     4      -           1975 Mar 10  Titan 34B/Agena     295 x 39338 x 63.5
     5      -           1978 Aug  5  Titan 34B/Agena     315 x 39053 x 62.5
     6      -           1981 Apr 24  Titan 34B/Agena     Orbital data unknown
     7      USA 4       1984 Aug 28  Titan 34B/Agena     342 x 38347 x 63.6
  

• Here is a list of more recent SDS HEO (highly elliptical orbit) satellites:

  SDS HEO Launches                     Parking orbit      Deployment orbit
  
  1989-61B  USA 40                     401 x 502 x 57.0   532 x  8135 x 57.0
  1992-86B  USA 89                     364 x 380 x 57.0   372 x  7300?x 56.9
  1996-38A  USA 125                    292 x 300 x 54.9   383 x 14072 x 55.4
  1998-05A  USA 137 (CAPRICORN)        191 x 795 x 62.5   Unknown
  2004-34A  USA 179 (NROL-1/NEMESIS)   191 x 400 x 58.4   267 x 15379 x 58.0
  2007-60A  USA 198 (NROL-24/SCORPIUS) 209 x 262 x 60.0   261 x 16776 x 60.0