Satellite Data System

American military satellite communication system

The current SDS-3 constellation, consisting of three Molniya orbit type and two geostationary satellites

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. It is believed that these satellites were known by the code name Quasar.[1] The first generation was named simply 'SDS', the second generation was named 'Quasar' and the third generation each had their own designations.[2]

## Orbital characteristics

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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 Company.

## Mission

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The primary purpose of the SDS satellites is to relay imagery from low-flying reconnaissance satellites, notably the Keyhole optical reconnaissance and Lacrosse/Onyx radar reconnaissance satellites to ground stations in the United States.[3]

## SDS-1

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Releasable Picture of NRO satellite, possible SDS-1 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.

Each SDS-1 satellite had 12 channels available for Ultra high frequency (UHF) communication. They were cylindrical in shape, roughly 25 ft (7.6 m) long. 980 watts of electrical power were available from solar panels and batteries. The SDS-1 had a mass of 630 kg (1,390 lb) and was launched on Titan-3B rockets. The SDS-1 satellites had similar orbits to the Air Force's Jumpseat ELINT satellites.[4]

It has been speculated that the early satellites served as data relays for the first KH-11 Kennen reconnaissance satellites.[5]

## SDS-2

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The SDS-2 is significantly more massive at 2,335 kg (5,148 lb), with three separate communication dishes, including one for a K-band downlink. Two dishes are 4.5 m (15 ft) in diameter, while the third is 2 m (6 ft 7 in) 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 IV launch vehicle.

## Satellites

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Name  | COSPAR ID[6]
SATCAT № | Launch date  | Launch vehicle  | Launch site  | Launch designation | Perigee | Apogee | Inclination  | Remarks

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### First generation

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OPS 7837 | 1976-050A
08871 | 2 June 1976  | Titan III(34)B | VAFB, SLC-4W | SDS F-1  | 380 km  | 39315 km  | 63.3 deg  |
OPS 7940 | 1976-080A
09270 | 6 August 1976  | Titan III(34)B | VAFB, SLC-4W | SDS F-2  | 380 km  | 39315 km  | 63.3 deg  |
OPS 7310 | 1978-075A
10993 | 5 August 1978  | Titan III(34)B | VAFB, SLC-4W | SDS F-3  | 380 km  | 39315 km  | 63.3 deg  |
OPS 5805 | 1980-100A
12093 | 13 December 1980  | Titan III(34)B | VAFB, SLC-4W |  |  |  |  |
USA-4 | 1984-091A
15226 | 28 August 1984  | Titan III(34)B | VAFB, SLC-4W | SDS F-5A  |  |  |  |
USA-9 | 195-014A
15546 | 8 February 1985  | Titan III(34)B | VAFB, SLC-4W | USA-9  |  |  |  |
USA-21 | 1987-015A
17506 | 15 February 1987  | Titan III(34)B | VAFB, SLC-4W | SDS F-6  |  |  |  |

### Second generation

[edit]

USA-40 | 1989-061B
20167 | 2 June 1989  | Space Shuttle Columbia
STS-28/Orbus-21S | KSC, LC-39B | N/A  |  |  |  |
USA-67 | 1990-097B
20963 | 15 November 1990  | Space Shuttle Atlantis
STS-38/Orbus-21S | KSC, LC-39A |  |  |  | Geosynchronous satellite, deployed along with Prowler and initially misidentified as a Magnum SIGINT spacecraft
USA-89 | 1992-086B
22518 | 2 December 1992  | Space Shuttle Discovery
STS-53/Orbus-21S | KSC, LC-39A |  |  |  |
USA-125 | 1996-038A
23945 | 3 July 1996  | Titan IV(405)A | CCAFS, LC-40 |  |  |  |

### Third generation

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USA-137 | 1998-005A
25148 | 29 January 1998  | Atlas IIA | CCAFS, SLC-36A | NROL-5  |  |  |  | Capricorn, Molniya orbit
USA-155 | 2000-080A
26635 | 6 December 2000  | Atlas IIAS | CCAFS, SLC-36A | NROL-10  |  |  |  | Great Bear, geosynchronous satellite at 10° West
USA-162 | 2001-046A
26948 | 11 October 2001  | Atlas IIAS | CCAFS, SLC-36B | NROL-12  |  |  |  | Aquila, geosynchronous satellite at 144° West
USA-179 | 2004-034A
28384 | 31 August 2004  | Atlas IIAS | CCAFS, SLC-36A | NROL-1  |  |  |  | Nemesis, Molniya orbit, final Atlas II launch
USA-198 | 2007-060A
32378 | 10 December 2007  | Atlas V 401  | CCAFS, SLC-41 | NROL-24  |  |  |  | Scorpius, Molniya orbit
USA-227 | 2011-011A
37377 | 11 March 2011  | Delta IV-M+(4,2) | CCAFS, SLC-37B | NROL-27  |  |  |  | Gryphon, geosynchronous satellite at 10° West, replaced USA-155
USA-236 | 2012-033A
38466 | 20 June 2012  | Atlas V 401  | CCAFS, SLC-41 | NROL-38  |  |  |  | Drake, geosynchronous satellite at 144° West, replacement for USA-162
USA-252 | 2014-027A
39751 | 22 May 2014  | Atlas V 401  | CCAFS, SLC-41 | NROL-33  |  |  |  | Geosynchronous satellite
USA-269 | 2016-047A
41724 | 28 July 2016  | Atlas V 421  | CCAFS SLC-41 | NROL-61  |  |  |  | Spike, Geosynchronous orbit, might be a new generation [7]
USA-279 | 2017-066A
42973 | 15 October 2017  | Atlas V 421  | CCAFS, SLC-41 | NROL-52 |  |  |  | Likely Geosynchronous orbit[8]

## References

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* Spaceflight portal

1. ^ Jonathan's Space Report: NRO Satellite Names
2. ^ Jonathan's Space Report: Satellite Catalogue
3. ^ Richelson, J.T. (2001). The Wizards of Langley. Inside the CIA's Directorate of Science and Technology. Boulder, Colorado: Westview Press. ISBN 9780813340593.
4. ^ National Reconnaissance Office: "NRO Brochure circa 1997"[permanent dead link]
5. ^ Day, Dwayne A. (26 February 2018). "Shadow dancing: the Satellite Data System". The Space Review.
6. ^ Jonathan's Space Report: List of satellite launches
7. ^ "NROL-61 satellite launched Thursday spotted in space by sky-watchers". Spaceflight Now. 30 July 2016.
8. ^ Graham, William (15 October 2017). "Atlas V finally launches with NROL-52". NASASpaceFlight.com. Retrieved 15 October 2017.

* Vick, Berman, Lindborg, Fellow (March 19, 1997) SDS-1 Military Communications Satellite Archived 28 August 2016 at the Wayback Machine Federation of American Scientists Accessed April 24, 2004
* Vick, Berman, Lindborg, Fellow, Pike, Aftergood (March 19, 1997) SDS-2 Military Communications Satellite Archived 20 September 2016 at the Wayback Machine Federation of American Scientists Accessed April 24, 2004

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National Reconnaissance Office

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* Sentient (intelligence analysis system) (2009-unknown)
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History|

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Founders|

* William O. Baker
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* William J. Perry
* Edward M. Purcell

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Satellites of the National Reconnaissance Office

Imaging|

| Optical|

| Keyhole|

* Corona
* Argon
* Lanyard
* Gambit 1
* Gambit 3
* Hexagon
* Kennen/Crystal

|

Misty|

* Misty
* EIS

Other|

* Samos

Radar|

* Quill
* Lacrosse/Onyx
* FIA-R

SIGINT|

| Radar location|

* Canyon
* Chalet/Vortex
* Mercury

|

Ship location|

* Poppy
* NOSS

ELINT|

| GEO|

* Rhyolite/Aquacade
* Magnum/Orion
* Mentor

|

HEO|

* Jumpseat
* Trumpet

LEO|

* Samos-F
* Poppy

Communication|

* SDS
* SLDCOM

Technology|

* STEX
* GeoLITE
* USA-193
* Colony
* RPP

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