Defense Satellite Communications System
{{Short description|Defense satellite communications project}}
{{Use American English|date = March 2019}}
{{Use dmy dates|date = March 2019}}
The Defense Satellite Communications System (DSCS){{cite book |last=Burroughs |first=William E. |year=1986 |title=Deep Black |location=New York |publisher=Berkley Publishing Group |isbn=0-425-10879-1 |pages=[https://archive.org/details/deepblackspacees00burr/page/187 187] |url-access=registration |url=https://archive.org/details/deepblackspacees00burr/page/187 }} is a United States Space Force satellite constellation that provides the United States with military communications to support globally distributed military users. Beginning in 2007, DSCS began being replaced by the Wideband Global SATCOM system. A total of 14 DSCS-III satellites were launched between the early 1980s and 2003. Two satellites were launched aboard the Space Shuttle Atlantis in 1985 during the STS-51-J flight. As of 14 September 2021, six DSCS-III satellites were still operational.{{cite web
|url=http://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/
|title=DSCS III Constellation
|work=Air Force Fact Sheet
|access-date=26 April 2017
|archive-url=https://web.archive.org/web/20170427103500/http://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/
|archive-date=27 April 2017
|url-status=dead
}} DSCS operations are currently run by the 4th Space Operations Squadron out of Schriever Space Force Base.
Background
DSCS went through three major phases — IDCSP (Interim Defense Communication Satellite Program), DSCS-II, and DSCS-III. Since the first launch, DSCS has been the "workhorse" of military satellite communications. All DSCS III satellites have exceeded their 10-year design life. The National Science Foundation use the DSCS satellites to provide additional bandwidth to Amundsen–Scott South Pole Station and McMurdo Station on Ross Island on the continent of Antarctica.{{cite web
|url=http://www.southpolestation.com/trivia/10s/10s.html#goes
|title=DSCS III use for Antarctica
|work=Amundsen-Scott South Pole Station
|access-date=26 April 2017
|archive-url=https://web.archive.org/web/20170427103507/http://www.southpolestation.com/trivia/10s/10s.html#goes
|archive-date=27 April 2017
|url-status=live
}}
IDCSP
{{Main|Initial Defense Communications Satellite Program}}
In April 1960, the Advanced Research Projects Agency (ARPA) initiated the Advent program, aiming to deliver a military communication satellite. However, the design concept surpassed the technological capabilities of the time, leading to the cancellation of the program in May 1962. The Initial Defense Communications Satellite Program (IDCSP) was proposed as one of two recommended follow-up approaches to deliver a working satellite.
Philco (now Ford Aerospace) was contracted for the work. The IDCSP delivered a simple, spin-stabilized satellite placed into a sub-synchronous orbit that did not require station-keeping or active altitude control. The capacity was approximately 1 Mbit/s digital data.
The first launch, comprising 7 satellites, took place in June 1966. The system was declared operational with the 1968 launch and renamed to Initial Defense Satellite Communication System (IDSCS).{{cite book |last=Martin |first=Donald H. |year=1986|title=Communication Satellites 1958-1988|location=El Segundo |publisher=Aerospace Corp.|pages=285}}
A total of 34 IDSCS satellites were built, with 8 lost in a launch failure in August 1966.{{Cite web|url=https://www.planet4589.org/space/log/satcat.txt|title=Satellite Catalog|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=27 April 2021}}
DSCS II
{{multiple image |align=right |total_width=450
|image1=DSCS-2 2.jpg |caption1=Illustration of a DSCS II satellite
|image2=US DoD DSCS Overview-1977.ogv |caption2=Overview of DSCS II, circa 1977
}}
DSCS II, developed under Program 777{{Cite book |url=https://books.google.com/books?id=_azf94TByF8C&q=777+DSCS&pg=PA181 |title=Communication Satellites |last=Martin |first=Donald H. |date=2000 |publisher=AIAA |isbn=9781884989094 |language=en}} provided secure voice and data transmission for the United States Armed Forces. The program was managed by the Defense Communications Agency (DCA), now the Defense Information Systems Agency.
The space vehicles were spin stabilized with a de-spun antenna platform. The body was mounted with solar cells, which produced 535 watts. Three NiCd batteries provided electrical power and it was supported by a hydrazine propulsion subsystem.
The communications payload included two 20-watt X band channels. The transponders were supported by steerable narrow beam antennas and drive mechanism for communications privacy.
The first DSCS II launch was in 1971.{{cite encyclopedia |url=http://www.astronautix.com/d/dscsii.html |title=DSCS II |encyclopedia=Encyclopedia Astronautica |access-date=27 April 2017 |archive-url=https://web.archive.org/web/20170626195308/http://www.astronautix.com/d/dscsii.html |archive-date=26 June 2017 |url-status=dead }}
DSCS III
On 12 December 1975, research and development contracts were awarded to General Electric and Hughes Aircraft Company[https://babel.hathitrust.org/cgi/pt?id=mdp.39015074749436;view=1up;seq=719 Fiscal year 1977 authorization for military procurement], pt. 6, p. 3769. to begin DSCS III design studies, with the first Block 1 launch on 30 October 1982.
DSCS III satellites support globally distributed Department of Defense (DoD) and national security users. The final 4 of 14 satellites received Service Life Enhancement Program (SLEP) modifications. These changes provided substantial capacity improvements through higher power amplifiers, more sensitive receivers, and additional antenna connectivity options. The DSCS communications payload includes six independent Super High Frequency (SHF) transponder channels that cover a 500 MHz bandwidth. Three receive and five transmit antennas provide selectable options for Earth coverage, area coverage and/or spot beam coverage. A special purpose single-channel transponder is also on board.{{cite web
|url=http://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/
|title=DSCS III
|work=Air Force Fact Sheet
|access-date=26 April 2017
|archive-url=https://web.archive.org/web/20170427103500/http://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/
|archive-date=27 April 2017
|url-status=dead
}}
=DSCS III Spacecraft=
| class="wikitable" |
| Spacecraft Name
! Other Designation ! Launch date/time (UTC) ! Rocket ! Status/Remarks |
|---|
| DSCS III-01
|DSCS III-A1 |1982-10-30, 04:05:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1982-106B 1982-106B] |Decommissioned/Launched with DSCS II-16 |
| USA-11
|DSCS III-B4 |1985-10-03, 15:15:30 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-092B 1985-092B] |Decommissioned{{cite web |url=https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/ |title=Defense Satellite Communications System |work=United States Air Force |date=November 2015 |access-date=7 January 2023 |archive-date=7 January 2023 |archive-url=https://web.archive.org/web/20230107212437/https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104555/defense-satellite-communications-system/ |url-status=dead }} |
| USA-12
|DSCS III-B5 |1985-10-03, 15:15:30 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-092C 1985-092C] |
| USA-43
|DSCS III-06 or DSCS III-A2 |1989-09-04, 05:54:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-069A 1989-069A] |
| USA-44
|DSCS III-07 |1989-09-04, 05:54:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-069B 1989-069B] | |
| USA-78
|DSCS III-08 |1992-02-10, 00:41:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-006A 1992-006A] |
| USA-82
|DSCS III-09 |1992-07-02, 21:54:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-037A 1992-037A] |
| USA-93
|DSCS III-10 |1993-07-19, 22:04:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1993-046A 1993-046A] |
| USA-97
|DSCS III-11 |1993-11-28, 23:40:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1993-074A 1993-074A] | |
| USA-113
|DSCS III-B7 |1995-07-31, 23:30:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1995-038A 1995-038A] |Decommissioned on 9 December 2022.{{cite web |last=Gibson |first=Hillary |url=https://www.spoc.spaceforce.mil/News/Article-Display/Article/3245751/spoc-officially-retires-dscs-satellite |title=SpOC officially retires DSCS satellite |work=Space Operations Command |publisher=United States Space Force |date=14 December 2022 |access-date=2 January 2023}} |
| USA-134
|DSCS III-B13 |1997-10-25, 00:46:00 |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1997-065A 1997-065A] |
| USA-148
|DSCS III-B11 |2000-01-25, 01:03:00 UTC |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2000-001A 2000-001A] |
| USA-167
|DSCS III-A3 |2003-03-11, 00:59:00 UTC |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2003-008A 2003-008A] |
| USA-170
|DSCS III-B6 |2003-08-29, 23:13:00 UTC |[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2003-040A 2003-040A] |
Image gallery
File:DSCS 2 diagram.PNG|DSCS-2 diagram
File:DSCS 3 diagram.PNG|DSCS-3 diagram
See also
References
{{reflist}}
External links
- [http://www.lockheedmartin.com/us/products/dscs.html Lockheed Martin's Page on DSCS]
- [http://www.fas.org/spp/military/program/com/dscs_3.htm Federation of American Scientists - DSCS 3]
- [https://www.losangeles.spaceforce.mil/?id=5322 U.S. Air Force MILSATCOM - DSCS]
- [https://web.archive.org/web/20070429104831/http://msl.jpl.nasa.gov/Programs/dscs.html NASA JPL - DSCS]
- [https://web.archive.org/web/20130917233415/http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104555/defense-satellite-communications-system.aspx Air Force - DSCS III]
- [http://nssdc.gsfc.nasa.gov/nmc/SpacecraftQuery.jsp NASA's National Space Science Data Center (NSSDC) - Master Catalog - Spacecraft Query]
{{USAF space vehicles}}
{{Use American English|date=January 2014}}
6
Category:Communications satellite constellations
Category:Military communications of the United States
Category:Military satellites of the United States
Category:Spacecraft launched by Atlas rockets
Category:Spacecraft launched by Delta IV rockets
Category:Spacecraft launched by the Space Shuttle
Category:Spacecraft launched by Titan rockets
Category:Equipment of the United States Space Force