Editing Satellite Data System

{{Short description|American military satellite communication system}}
{{Use American English|date=January 2019}}
{{Use dmy dates|date=January 2021}}

[[File:SDS3 const.png|thumb|upright=1.3|right|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 satellite|military communications satellite]]s.  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''.<ref>[http://planet4589.org/nro/nro.html Jonathan's Space Report: ''NRO Satellite Names'']</ref> The first generation was named simply 'SDS', the second generation was named 'Quasar' and the third generation each had their own designations.<ref>[http://planet4589.org/space/log/satcat.txt Jonathan's Space Report: ''Satellite Catalogue'']</ref>

== Orbital characteristics ==
SDS satellites have a [[highly elliptical orbit]], going from about 300 kilometers at [[Apsis|perigee]] to roughly 39,000&nbsp;km at [[Apsis|apogee]] in order to allow communications with [[Geographical pole|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 ==
The primary purpose of the SDS satellites is to relay imagery from low-flying [[reconnaissance satellite]]s, notably the [[Corona (satellite)|Keyhole]] optical reconnaissance and [[Lacrosse (satellite)|Lacrosse/Onyx]] radar reconnaissance satellites to ground stations in the [[United States]].<ref name=Richelson>{{cite book |last=Richelson |first=J.T. |date=2001 |title=The Wizards of Langley. Inside the CIA's Directorate of Science and Technology |location=Boulder, Colorado |publisher=Westview Press |isbn=9780813340593}}</ref>

== SDS-1 ==
[[File:NRO comm satellite.PNG|thumb|upright=1.3|right|Releasable Picture of NRO satellite, possible SDS-1]]
[[File:USA179 SDS 3 4.jpg|thumb|upright=1.3|right|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 [[Cylinder|cylindrical]] in shape, roughly {{cvt|25|ft|m}} long. 980 [[watt]]s of electrical power were available from [[Photovoltaic module|solar panel]]s and [[Electric battery|batteries]]. The SDS-1 had a mass of {{cvt|630|kg}} and was launched on [[Titan (rocket family)|Titan-3B]] rockets. The SDS-1 satellites had similar orbits to the Air Force's [[Jumpseat (satellite)|Jumpseat]] [[Signals intelligence|ELINT]] satellites.<ref>[http://www.zianet.com/jpage/black/NRO%20Brochure.pdf National Reconnaissance Office: "NRO Brochure circa 1997"]{{dead link|date=December 2017|bot=InternetArchiveBot|fix-attempted=yes}}</ref>

It has been speculated that the early satellites served as data relays for the first [[KH-11 Kennen]] reconnaissance satellites.<ref name=TheSpaceReview20180267>{{cite web|first=Dwayne A.|last=Day|date=26 February 2018|url=http://www.thespacereview.com/article/3440/1|title=Shadow dancing: the Satellite Data System|publisher=The Space Review}}</ref>

== SDS-2 ==
The SDS-2 is significantly more massive at {{cvt|2335|kg}}, with three separate communication dishes, including one for a [[K band (IEEE)|K-band]] downlink. Two dishes are {{cvt|4.5|m}} in diameter, while the third is {{cvt|2|m}} in diameter. The solar arrays generate 1238 watts of power. It is believed that the [[Space Shuttle program|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 ==
{|class="wikitable"
|-
! Name
! [[International Designator|COSPAR ID]]<ref>[http://planet4589.org/space/log/ Jonathan's Space Report: ''List of satellite launches'']</ref><br/><small>[[Satellite Catalog Number|SATCAT №]]</small>
! Launch date
! Launch vehicle
! Launch site
! [[List of NRO Launches|Launch designation]]
! [[Perigee]]
! [[Apogee]]
! Inclination
! Remarks
|-
| colspan=10|

=== First generation ===
|-
| [[OPS 7837]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1976-050A 1976-050A]<br/><small>08871</small>
| 2 June 1976
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| SDS F-1
| 380 km
| 39315 km
| 63.3 deg
| 
|-

| [[OPS 7940]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1976-080A 1976-080A]<br/><small>09270</small>
| 6 August 1976
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| SDS F-2
| 380 km
| 39315 km
| 63.3 deg
| 
|-

| [[OPS 7310]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-075A 1978-075A]<br/><small>10993</small>
| 5 August 1978
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| SDS F-3
| 380 km
| 39315 km
| 63.3 deg
|
|-

| [[OPS 5805]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1980-100A 1980-100A]<br/><small>12093</small>
| 13 December 1980
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| 
| 
| 
| 
| 
|-

| [[USA-4]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-091A 1984-091A]<br/><small>15226</small>
| 28 August 1984
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| SDS F-5A
| 
| 
| 
| 
|-

| [[USA-9]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-014A 195-014A]<br/><small>15546</small>
| 8 February 1985
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| USA-9
| 
| 
| 
| 
|-

| [[USA-21]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1987-015A 1987-015A]<br/><small>17506</small>
| 15 February 1987
| [[Titan IIIB|Titan III(34)B]]
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 4|SLC-4W]]
| SDS F-6
|
| 
| 
| 
|-
| colspan=10|

=== Second generation ===
|-
| [[USA-40]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-061B 1989-061B]<br/><small>20167</small>
| 2 June 1989
| {{OV|102}}<br/>[[STS-28]]/[[Orbus-21S]]
| [[Kennedy Space Center|KSC]], [[Kennedy Space Center Launch Complex 39B|LC-39B]]
| rowspan=4| N/A
| 
| 
| 
| 
|-

| [[USA-67]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1990-097B 1990-097B]<br/><small>20963</small>
| 15 November 1990
| {{OV|104}}<br/>[[STS-38]]/[[Orbus-21S]]
| [[Kennedy Space Center|KSC]], [[Kennedy Space Center Launch Complex 39A|LC-39A]]
| 
| 
| 
| Geosynchronous satellite, deployed along with [[Prowler (satellite)|Prowler]] and initially misidentified as a [[Magnum (satellite)|Magnum]] SIGINT spacecraft
|-

| [[USA-89]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-086B 1992-086B]<br/><small>22518</small>
| 2 December 1992
| {{nowrap|{{OV|103}}}}<br/>[[STS-53]]/[[Orbus-21S]]
| [[Kennedy Space Center|KSC]], [[Kennedy Space Center Launch Complex 39A|LC-39A]]
| 
| 
| 
| 
|-

| [[USA-125]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-038A 1996-038A]<br/><small>23945</small>
| 3 July 1996
| [[Titan IV|Titan IV(405)A]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 40|LC-40]]
| 
| 
| 
| 
|- 
| colspan=10|

=== Third generation ===
|-
| [[USA-137]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-005A 1998-005A]<br/><small>25148</small>
| 29 January 1998
| [[Atlas II|Atlas IIA]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Launch Complex 36|SLC-36A]]
| NROL-5
| 
| 
| 
| ''Capricorn'', [[Molniya orbit]]
|-

| [[USA-155]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2000-080A 2000-080A]<br/><small>26635</small>
| 6 December 2000
| [[Atlas II|Atlas IIAS]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Launch Complex 36|SLC-36A]]
| NROL-10
| 
| 
| 
| ''Great Bear'', geosynchronous satellite at 10° West
|-

| [[USA-162]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2001-046A 2001-046A]<br/><small>26948</small>
| 11 October 2001
| [[Atlas II|Atlas IIAS]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Launch Complex 36|SLC-36B]]
| NROL-12
| 
| 
| 
| ''Aquila'', geosynchronous satellite at 144° West
|-

| [[USA-179]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-034A 2004-034A]<br/><small>28384</small>
| 31 August 2004
| [[Atlas II|Atlas IIAS]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Launch Complex 36|SLC-36A]]
| NROL-1
| 
| 
| 
| ''Nemesis'', [[Molniya orbit]], final Atlas II launch
|-

| [[USA-198]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-060A 2007-060A]<br/><small>32378</small>
| 10 December 2007
| [[Atlas V]] 401
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 41|SLC-41]]
| NROL-24
| 
| 
| 
| ''Scorpius'', [[Molniya orbit]]
|-

| [[USA-227]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2011-011A 2011-011A]<br/><small>37377</small>
| 11 March 2011
| [[Delta IV|Delta IV-M+(4,2)]]
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| NROL-27
| 
| 
| 
| ''Gryphon'', geosynchronous satellite at 10° West, replaced USA-155
|-

| [[USA-236]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2012-033A 2012-033A]<br/><small>38466</small>
| 20 June 2012
| [[Atlas V]] 401
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Air Force Station Space Launch Complex 41|SLC-41]]
| NROL-38
| 
| 
| 
| ''Drake'', geosynchronous satellite at 144° West, replacement for USA-162
|-

| [[USA-252]]
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2014-027A 2014-027A]<br/><small>39751</small>
| 22 May 2014
| [[Atlas V]] 401
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 41|SLC-41]]
| NROL-33
| 
| 
| 
| Geosynchronous satellite
|-

| [[USA-269]]
| {{COSPAR|2016-047A}}<br/><small>41724</small>
| 28 July 2016
| [[Atlas V]] 421
| [[Cape Canaveral Air Force Station|CCAFS]] [[Cape Canaveral Air Force Station Space Launch Complex 41|SLC-41]]
| NROL-61
| 
| 
| 
| ''Spike'', [[Geosynchronous orbit]], might be a new generation <ref>{{cite news|url=https://spaceflightnow.com/2016/07/30/nrol-61-satellite-launched-thursday-spotted-in-space-by-sky-watchers/|title=NROL-61 satellite launched Thursday spotted in space by sky-watchers|publisher=Spaceflight Now|date=July 30, 2016}}</ref>
|-

| [[USA-279]]
| {{COSPAR|2017-066A}}<br/><small>42973</small>
| 15 October 2017
| [[Atlas V]] 421
| [[Cape Canaveral Space Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 41|SLC-41]]
| [[List of NRO launches|NROL-52]]
| 
| 
| 
| Likely [[Geosynchronous orbit]]<ref>{{cite news|url=https://www.nasaspaceflight.com/2017/10/ula-atlas-v-nrol-52-launch-cape-canaveral/|title=Atlas V finally launches with NROL-52 |publisher=NASASpaceFlight.com|first=William|last=Graham|date=October 15, 2017|access-date=October 15, 2017}}</ref>

|}

== References ==
{{Portal|Spaceflight}}
{{Reflist|30em}}

* Vick, Berman, Lindborg, Fellow (March 19, 1997) [https://fas.org/spp/military/program/com/sds_1.htm SDS-1 Military Communications Satellite] {{Webarchive|url=https://web.archive.org/web/20160828024008/http://fas.org/spp/military/program/com/sds_1.htm |date=28 August 2016 }} ''Federation of American Scientists''  Accessed April 24, 2004
* Vick, Berman, Lindborg, Fellow, Pike, Aftergood (March 19, 1997) [https://fas.org/spp/military/program/com/sds_2.htm SDS-2 Military Communications Satellite] {{Webarchive|url=https://web.archive.org/web/20160920050553/https://fas.org/spp/military/program/com/sds_2.htm |date=20 September 2016 }} ''Federation of American Scientists''  Accessed April 24, 2004

{{NRO satellites}}

[[Category:Communications satellites]]
[[Category:Hughes Aircraft Company]]
[[Category:Military satellites]]