{{Short description|US space force communication system}} thumb|FLTSATCOM Satellite '''FLTSATCOM''' (also '''FLTSAT''') is a satellite communication system controlled by the U.S. Space Force (formally SPAWARSYSCOM) which was used for UHF radio communications between ships, submarines, airplanes and ground stations of the Navy.<ref>{{cite news | url=https://spacenews.com/army-navy-satellite-operations-to-consolidate-under-space-force/ | title=Army, Navy satellite operations to consolidate under Space Force | first=Sandra |last=Irwin |publisher=Space News |date=23 June 2021 |access-date=May 24, 2025}}</ref>
Most of the transponders on these satellites were simple repeaters with no authentication or control over what they retransmitted.<ref>{{cite web|title=Hunting for Space Radio Pirates on the US Military Fleet Satcom Satellites |date=March 3, 2023 |url=https://www.rtl-sdr.com/hunting-for-space-radio-pirates-on-the-us-military-flt-satcom-satellites/ |website=rtl-sdr.com |access-date=May 24, 2025}}</ref>
==Satellite Characteristics== thumb|Launch of Atlas G AC-66 rocket with FLTSATCOM-7 Altogether eight satellites were launched from 1978 to 1989 by Atlas-Centaur rockets into geostationary orbit.<ref name=":0">{{Cite web |title=FLTSATCOM 1, 2, 3, 4, 5 (Block 1) |url=https://space.skyrocket.de/doc_sdat/fltsatcom-1.htm |access-date=2025-11-21 |website=Gunter's Space Page |language=en}}</ref><ref name=":1">{{Cite web |title=FLTSATCOM 6, 7, 8 (Block 2) |url=https://space.skyrocket.de/doc_sdat/fltsatcom-2.htm |access-date=2025-11-21 |website=Gunter's Space Page |language=en}}</ref> The system became operational in 1981. The satellites were manufactured by TRW. The solar array of each satellite had a span of over 13.2 m. A special characteristic was a UHF transmit antenna reflector 4.9 m in diameter.<ref>{{cite web|title=FLTSATCOM Fleet Satellite Communications System |website=Globalsecurity.org |url=https://www.globalsecurity.org/space/systems/fltsat.htm |access-date=May 24, 2025}}</ref> Each satellite had 12 transponders, which worked in the UHF range from 240 - 400 megahertz. Additionally FLTSATCOM 7 and 8 included an experimental EHF transponder built by Lincoln Laboratory intended to test the MILSTAR ground terminals. The first seven satellites each had a launch mass of 1884 kg and the remaining two were 2310 kg, with the additional mass due to the EHF payload module.<ref>{{cite web |work= NASA Mission and Spacecraft Library |url= http://msl.jpl.nasa.gov/QuickLooks/fltsatcomQL.html |title= QuickLooks FLTSATCOM |archive-url= https://web.archive.org/web/20060929054027/http://msl.jpl.nasa.gov/QuickLooks/fltsatcomQL.html |archive-date= 29 September 2006 |url-status= dead |publisher= NASA JPL }}</ref><ref name=":0" />
In the late 1990s, FLTSATCOM satellites were gradually replaced by the UFO satellites.<ref>{{cite web|title=From the Sea to the Stars - A Chronicle of the U.S. Navy's Space and Space-related Activities, 1944-2009 |url=https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/f/from-sea-stars.html#bookmark161 |page=116 |website=navy.mil |date=2010|access-date=May 24, 2025}}</ref>
FLTSATCOM 7 and FLTSATCOM 8 have been used for repeating UHF Satcom transmissions by unauthorized radio users particularly in Brazil, including criminals, illegal loggers, truckers and individuals located in remote areas. This has been met with limited law enforcement action.<ref>{{cite magazine|url=https://www.wired.com/2009/04/fleetcom/|title=The Great Brazilian Sat-Hack Crackdown|last=Soares|first=Marcelo|date=2009-04-20|magazine=Wired|accessdate=2018-09-03}}</ref>
{{As of|September 2025}}, only one remains operational.<ref>{{Cite web|url=https://nps.edu/-/the-last-telemetry-of-fltsatcom|date=September 11, 2025|access-date=November 20, 2025|title=The Last Telemetry of FLTSATCOM|first=Dan|last=Linihan|publisher=Naval Postgraduate School}}</ref>
==Launches== Altogether eight satellites were launched from 1978 to 1989 by Atlas-Centaur rockets into geostationary orbit. The system became operational in 1981.<ref>{{cite web|title=FLTSATCOM |first=Mark |last=Wade |url=http://www.astronautix.com/f/fltsatcom.html |website=astronautix.com |access-date=May 25, 2025}}</ref><ref name=":0" /><ref name=":1" />
The fifth satellite reached geosynchronous orbit, but had severely limited utility due to damage to the solar arrays and antennas. The failure was attributed to explosive delamination of the fiberglass honeycomb fairing during flight. The inside wall of the fairing extensively damaged one of the solar arrays, and bent the transmit antenna mast which prevented the antenna from deploying fully.<ref>{{cite news|title=Launch failures: fairings |first=Wayne |last=Eleazer |date=March 28, 2022 |url=https://www.thespacereview.com/article/4354/1 |publisher=Space Review |access-date=May 25, 2025}}</ref>
Flight 7 was launched out of sequence after a launch failure of a Delta mission carrying the GOES-G weather satellite grounded the entire US launch fleet weeks prior to the scheduled launch of F-6. By the time the Delta mishap investigation concluded there was no risk to the Atlas-Centaur system, F-7 was ready to launch and the system managers elected to swap missions to avoid delaying EHF system testing.
Flight 6 was destroyed in a launch failure. The Atlas-Centaur was launched on March 26, 1987 into a heavy overcast with light rain. 51 seconds into the flight, the Atlas was struck by lightning and the resulting EMP changed a value in the guidance computer's core memory, causing the rocket to yaw and break apart from aerodynamic stress. As a result of this mishap, NASA and the Air Force re-emphasised and clarified the original weather guidelines developed after the Apollo 12 on-stand lightning strike for all future launches.<ref name="ac67">{{cite journal|title=The Atlas-Centaur 67 incident |first1=H.J. |last1=Christian |first2= K. |last2=Crouch |first3=B. |last3=Fisher |first4=V. |last4=Mazur |first5=R.A. |last5=Perala |first6=L. |last6=Ruhnke |doi=10.2514/6.1988-389 |journal=26th Aerospace Sciences Meeting |date=January 1988}}</ref>
===Launch Data=== {| class="wikitable sortable" ! |Satellite ! |Date/Time (UTC) ! |Rocket !S/N !Image ! |Note |- |FLTSATCOM 1<ref>{{cite web |title=NSSDCA - FLTSATCOM 1 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-016A |website=NASA |access-date=May 24, 2025}}</ref> | 1978-02-09 21:17:01 | Atlas-SLV3D |AC-44 |frameless|150x150px | {{Success}} |- |FLTSATCOM 2<ref>{{Cite book |url=https://ntrs.nasa.gov/api/citations/19790012938/downloads/19790012938.pdf?attachment=true |title=Mission Operation Report FLTSATCOM-B |date=May 1979 |publisher=NASA}}</ref> | 4 May 1979 18:57:00 | Atlas-SLV3D |AC-47 |frameless|197x197px | {{Success}} |- |FLTSATCOM 3 | 1980-01-18 01:26:00 | Atlas-SLV3D |AC-49 | | {{Success}} |- |FLTSATCOM 4 | 1980-10-31 03:54:00 | Atlas-SLV3D |AC-57 | | {{Success}} |- |FLTSATCOM 5 | 1981-08-06 08:16:00 | Atlas-SLV3D |AC-59 | | Damaged upon launch |- |FLTSATCOM 7<ref>{{cite web|title=NSSDCA - FLTSATCOM 7 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1986-096A |website=NASA |access-date=May 24, 2025}}</ref> | 1986-12-05 02:30:01 | Atlas-G |AC-66 |frameless|150x150px | {{Success}} |- |FLTSATCOM 6 | 1987-03-26
| Atlas-G |AC-67 | | Lightning strike destroyed the rocket<ref name="ac67"/> |- |FLTSATCOM 8 | 1989-09-25 08:56:02 | Atlas-G |AC-68 |frameless|150x150px | {{Success}} |}
==See also== *Electronics Technician
==References== {{Reflist}}
==External links== * FLTSATCOM Flight 6 Launch Book - TRW Electronics and Defense Sector, April 1986
Category:Military communications of the United States Category:Communications satellites Category:Satellites in geosynchronous orbit Category:Equipment of the United States Space Force