View source for Engineering:UHF Follow-On (satellite)

{{nofootnotes|date=January 2018}}

{{Infobox spacecraft class
| name         = Ultra High Frequency Follow-On
| names_list   = 
| image        = UFO satellite.jpg
| caption      = Artist's impression of an UHF Follow-On satellite in orbit
| image_size   = 300px

| country      = {{wipe|United States}}
| bus          = [[Engineering:Boeing 601|HS-601]]
| mass         = {{cvt|2844|kg}}
| orbits       = [[Astronomy:Geosynchronous orbit|Geosynchronous orbit]]
| lifetime     = 14 years (planned)

| operator     = United States Navy
| applications = [[Social:Military communications|Military communications]]
| status       = Active
| built        = 11
| launched     = 11
| operational  = 
| retired      = 
| failed       = 
| lost         = 1
| first        = 25 March 1993
| last         = 18 December 2003
}}

'''Ultra High Frequency Follow-On''' ('''UFO''') satellite system is a United States Department of Defense (DoD) program sponsored and operated by the United States Navy to provide communications for airborne, ship, submarine and ground forces. The UFO constellation replaced the U.S. DoD Fleet Satellite Communications System (FLTSATCOM) constellation and consisted of eleven satellites. The ground terminal segment consists of equipment and resident personnel at existing satellite communication stations. The satellites are controlled by the Naval Satellite Operations Center ([[Organization:Naval Network Warfare Command|NAVSOC]]) located at the Naval Base Ventura County, Point Mugu, {{wipe|California}}.

== Satellite description ==
The [[Physics:Ultra high frequency|Ultra high frequency]] (UHF) satellites primarily served tactical users. UFO provided almost twice as many channels as FLTSATCOM and has about 10% more power per channel. The [[Physics:Extremely high frequency|Extremely high frequency]] (EHF) package on satellites four through eleven have an Earth coverage beam and a steerable five-degree spot beam that enhances its tactical use. The EHF capability also allows the UFO network to connect to the strategic [[Engineering:Milstar|Milstar]] system. Satellites eight, nine and ten also carry the Global Broadcast Service antennas that operate in the [[Astronomy:Ka band|Ka-band]]. The [[Engineering:Atlas (rocket family)|Atlas]] was the [[Engineering:Launch vehicle|launch vehicle]] of choice; however, space shuttle compatibility existed. The UFO bus and payload weigh {{cvt|2844|kg}}.<ref name="NASA">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1993-015A|title=Display: UFO-1 1993-015A|publisher=NASA|date=27 April 2021|access-date=27 May 2021}} {{PD-notice}}</ref> The [[Physics:Solar panels on spacecraft|solar panels]] spans {{cvt|18.4|m}} and produces 2,500 [[Watt|watts]] at the end of the planned 14-year lifetime. The UHF system supports stationary and mobile users including manportable, ships, submarines, aircraft and other mobile terminals. The UFO Follow-On system is scheduled for replacement by the Mobile User Objective System (MUOS).

== Launch ==
First launch of the UFO took place on 25 March 1993, with constellation completion dependent on replacement needs for the aging FLTSATCOM constellation.

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

== External links ==
* Boeing: [https://web.archive.org/web/20070228081235/http://www.boeing.com/defense-space/space/bss/factsheets/601/uhf_followon/uhf_followon.html UFO System]
* GlobalSecurity.org: [http://www.globalsecurity.org/space/library/report/1999/nssrm/initiatives/ufo.htm UFO System]
* GlobalSecurity.org: [http://www.globalsecurity.org/space/systems/muos.htm MUOS system]

[[Category:Military communications]]

{{Sourceattribution|UHF Follow-On (satellite)|1}}