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{{Short description|1960s and 80s NASA program to develop communications satellites}}
{{More footnotes needed|date=July 2011}}
{{Use American English|date=July 2024}}
{{Use mdy dates|date=July 2024}}
[[File:Syncom colour.jpg|thumb|Artist's vision of Syncom satellite, 1963]]
'''Syncom''' (for "'''synchronous communication satellite'''") started as a 1961 [[NASA]] program for active [[geosynchronous]] [[communication satellite]]s, all of which were developed and manufactured by the Space and Communications division of [[Hughes Aircraft Company]] (now the [[Boeing Satellite Development Center]]). Syncom 2, launched in 1963, was the world's first geosynchronous communications satellite. Syncom 3, launched in 1964, was the world's first [[geostationary satellite]].{{Citation needed|date=July 2024}}

In the 1980s, the series was continued as Syncom IV with some much larger satellites, also manufactured by Hughes. They were leased to the [[United States military]] under the Leasat program.

==Syncom 1, 2 and 3==
=== Common features ===
[[File:Syncom 2 side.jpg|thumb|upright|First generation Syncom satellite]]The three early Syncom satellites were experimental spacecraft built by [[Hughes Aircraft Company]]'s facility in [[Culver City, California]], by a team led by [[Harold Rosen (electrical engineer)|Harold Rosen]], Don Williams, and Thomas Hudspeth.<ref>{{cite news |last=Wichter |first=Zach |date=February 2, 2017 |title=Harold Rosen, Who Ushered in the Era of Communication Satellites, Dies at 90 |url=https://www.nytimes.com/2017/02/02/business/harold-rosen-dead-engineer-satellite.html |work=The New York Times}}</ref> All three satellites were cylindrical in shape, with a diameter of about {{Convert|71|cm}} and a height of about {{Convert|39|cm}}.  Pre-launch fueled masses were {{Convert|68|kg}}, and orbital masses were {{Convert|39|kg}} with a {{Convert|25|kg|adj=on}} [[Payload (air and space craft)|payload]]. They were capable of emitting signals on two [[transponders]] at just 2&nbsp;[[watt|W]]. Thus, Syncom satellites were only capable of carrying a single two-way telephone conversation, or 16 [[Teleprinter|Teletype]] connections. {{As of|2009|6|25|post=,}} all three satellites are still in orbit, although no longer functioning.<ref>{{cite web |title=U.S. Space Objects Registry |url=https://usspaceobjectsregistry.state.gov/Pages/Search.aspx |archive-url=https://web.archive.org/web/20131006073413/https://usspaceobjectsregistry.state.gov/Pages/Search.aspx |archive-date=October 6, 2013 }}</ref>

=== Syncom 1 ===
[[File:Syncom launch sequence.jpg|thumb|Syncom launch sequence]]
'''Syncom 1''' was intended to be the first [[geosynchronous orbit|geosynchronous]] communications satellite.  It was launched on February 14, 1963, with the [[Delta (rocket family)|Delta B]] #16 [[expendable launch system|launch vehicle]] from [[Cape Canaveral]], but was lost on the way to geosynchronous orbit due to an electronics failure.<ref>{{cite magazine |url=http://www.time.com/time/magazine/article/0,9171,898835,00.html |title=The Room-Size World |date=May 14, 1965 |magazine=[[TIME]] |archive-url=https://web.archive.org/web/20090520010007/http://www.time.com/time/magazine/article/0,9171,898835,00.html |archive-date=May 20, 2009 }}
</ref> Seconds after the [[apogee]] kick motor for circularizing the orbit was fired, the spacecraft fell silent. Later telescopic observations verified the satellite was in an orbit with a period of almost 24 hours at a 33° inclination.

=== Syncom 2 ===
'''Syncom 2''' was launched by NASA on July 26, 1963<ref name="D-2911" /> with the [[Delta (rocket family)|Delta B]] #20 launch vehicle from Cape Canaveral. The satellite successfully kept station at the altitude calculated by [[Herman Potočnik|Herman Potočnik Noordung]] in the 1920s.

[[File:USNS Kingsport SYNCOM Call Kennedy-Balewa July 1963.png|thumb|[[Abubakar Tafawa Balewa|Prime Minister Balewa]] (2nd from right) talks to [[John F. Kennedy|President John F. Kennedy]] on the first live broadcast via the Syncom 2 satellite from [[USNS Kingsport|USNS ''Kingsport'']] in [[Lagos|Lagos, Nigeria]].]]

During the first year of Syncom 2 operations, NASA conducted voice, teletype, and facsimile tests,<ref name="D-2911">{{cite journal |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650019255.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650019255.pdf |archive-date=October 9, 2022 |url-status=live |title=Television Tests with the Syncom II Synchronous Communications Satellite (NASA technical note D-2911) |first1=Varice F. |last1=Henry |first2=Michael E. |last2=McDonald |journal=NTRS.nasa.gov |publisher=[[NASA]] |date=July 1965 |access-date=December 7, 2014}}</ref> as well as 110 public demonstrations to show the capabilities of this satellite and invite feedback. In August 1963, President [[John F. Kennedy]] in Washington, D.C., telephoned Nigerian Prime Minister [[Abubakar Tafawa Balewa]] aboard {{USNS|Kingsport|T-AG-164|6}} (the first satellite communication ship) docked in [[Lagos]] Harbor—the first live two-way call between heads of government by satellite. The ''Kingsport'' acted as a control station and uplink station.<ref>{{cite book |last1=Uhlig |first1=Thomas |last2=Sellmaier |first2=Florian |last3=Schmidhuber |first3=Michael |year=2014 |title=Spacecraft Operations |location=New York |publisher=Springer |isbn=9783709118023 |lccn=2014945749 |url=https://books.google.com/books?id=XbZTBAAAQBAJ&pg=PA312 |access-date=June 13, 2020}}</ref>{{Circular reference|date=September 2023}}<ref>{{cite book |last=Williamson |first=Mark |date=2006 |title=Spacecraft Technology: the early years |location=London |publisher=Institution of Electrical Engineers |isbn=9780863415531 |lccn=2008530215 |url=https://books.google.com/books?id=npI5NsFG8ngC&pg=PA185 |access-date=June 13, 2020}}</ref>

Syncom 2 also relayed a number of test television transmissions from [[Fort Dix|Fort Dix, New Jersey]] to a ground station in [[Andover, Maine]], beginning on September 29, 1963.  Although it was low-quality video with no audio, it was the first successful television transmission through a [[geosynchronous satellite]].<ref name="D-2911" />

=== Syncom 3 ===
[[File:Stamp of Ras al-Khaimah-1966-Television-Tower-with-Satellite-Syncom-3-and-Rocket (3).jpg|thumb|Stamp showing Syncom 3]]
'''Syncom 3''' was the first [[Geostationary orbit|geostationary]] communication satellite, launched on August 19, 1964, with the [[Delta rocket|Delta D]] #25 launch vehicle from Cape Canaveral.  The satellite, in orbit near the [[International Date Line]], had the addition of a wideband channel for television and was used to telecast the [[1964 Summer Olympics]] in [[Tokyo]] to the [[United States]].<ref>{{cite magazine |title=For Gold, Silver & Bronze |url=http://www.time.com/time/magazine/article/0,9171,876272,00.html |date=October 16, 1964 |archive-url=https://web.archive.org/web/20080421134503/http://www.time.com/time/magazine/article/0,9171,876272,00.html |archive-date=April 21, 2008 |magazine=[[TIME]] }}</ref> Although Syncom 3 is sometimes credited with the first television program to cross the [[Pacific Ocean]], the [[Relay 1]] satellite first broadcast television from the United States to Japan on November 22, 1963.<ref name="NASA-SP-93">{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660009169_1966009169.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660009169_1966009169.pdf |archive-date=October 9, 2022 |url-status=live |title=Significant Achievements in Space Communications and Navigation, 1958-1964 |date=1966 |work=NASA-SP-93 |publisher=NASA |pages=30–32 |access-date=October 31, 2009 }}</ref>{{Rp|1}}

=== Transfer to Department of Defense control ===
By the end of 1964, Syncoms 2 and 3 had completed NASA's R&D experiments. On January 1, 1965, NASA transferred operation of the satellites to the [[United States Department of Defense]] (DOD) along with telemetry, command stations, and range and rangefinding equipment. DOD had, in fact, provided the communications ground stations used to relay transmissions via the two Syncoms since their launch. DOD agreed to provide telemetry and ranging data of continuing scientific and engineering interest.{{Citation needed|date=July 2024}}

In 1965, Syncom 3 was implemented to support the DOD's communications in Vietnam.<ref name="aa1965">{{cite web |url=https://history.nasa.gov/AAchronologies/1965.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://history.nasa.gov/AAchronologies/1965.pdf |archive-date=October 9, 2022 |url-status=live |title=Aeronautics and Astronautics, 1965 |publisher=NASA |date=1966 |access-date=January 2, 2019 }}</ref>

Turned off in 1969, Syncom 3 remains in [[geosynchronous orbit]] {{As of|2024|lc=on|post=.}}<ref>{{cite web |title=Detailed information about SYNCOM 3 satellite, 1964-047A, TLE data for Norad 858 |url=http://www.infosatellites.com/syncom3-satellite-information-norad-858.html |website=Infosatellites.com |quote=The spacecraft next carried out a series of attitude and velocity maneuvers to align itself with the equator at an inclination of 0.1 degrees and to slow its speed so it drifted west to the planned location at 180 degrees longitude where its speed at altitude was synchronized with the Earth. |url-status=live |archive-url=https://web.archive.org/web/20160304114945/http://www.infosatellites.com/syncom3-satellite-information-norad-858.html |archive-date=March 4, 2016 |access-date=July 14, 2024 }}</ref> In 50 years it has drifted east, to longitude 123&nbsp;W.<ref>{{cite web |title=Track SYNCOM 3 Satellite in Real Time |url=http://www.infosatellites.com/syncom3-satellite-tracking-norad-858.html |website=Infosatellites.com |archive-url=https://web.archive.org/web/20160304032039/http://www.infosatellites.com/syncom3-satellite-tracking-norad-858.html |archive-date=March 4, 2016 }} Requires Javascript.</ref>

== Syncom IV (Leasat) ==
[[File:LEASAT satellite.jpg|thumb|Leasat (Syncom IV) satellite]]
[[File:STS-51-A Syncom IV-1 deployment.jpg|thumb|Leasat F1 satellite after deployment from STS-51-A]]
[[File:STS41D-36-111.jpg|thumb|Leasat F2 satellite after deployment from STS-41-D]]
[[File:Syncom LEASAT.jpg|thumb|Leasat F3 after its deployment from the shuttle Discovery during mission STS-51-D]]
[[File:Leasat 3 STS-51-I.jpg|thumb|Astronaut James van Hoften manipulating Leasat F3 satellite during STS-51-I]]
[[File:STS-51-I SYNCOM IV-4 deployment.jpg|thumb|Leasat F4 deployed<nowiki/> from the payload bay of the Shuttle Discovery on STS-51-I]]
[[File:1990 s32 Syncom 4-F5 Deployment.jpg|thumb|Leasat F4 released "frisbee-style" from the payload bay of Columbia on mission STS-32]]
The five satellites of the 1980s Leasat (Leased Satellite) program (Leasat F1 through Leasat F5) were alternatively named Syncom IV-1 to Syncom IV-5, all using Hughes' HS-381 platform of satellite.<ref name="summer1994">{{cite web |title=The Men Who Staff HCI's LEASAT Earth Stations Are Accustomed to Working on Their Own |date=Summer 1994 |archive-url=https://web.archive.org/web/19990505230020/http://www.spaceway.com/uplink/archive/up942/leasat942.html |archive-date=May 5, 1999 |url=http://www.spaceway.com/uplink/archive/up942/leasat942.html |work=Uplink |publisher=Hughes Communications }}</ref> These satellites were considerably larger than Syncoms 1 to 3, weighing 1.3 [[tonne]]s each (over 7 tonnes with launch fuel). At {{Convert|4.26|m}}, the satellites were the first to be designed for launch from the [[Space Shuttle]] payload bay,<ref name="fas">{{cite web |title=LEASAT |work=Military Space Programs |publisher=Federation of American Scientists |url=http://fas.org/spp/military/program/com/leasat.htm |archive-url=https://web.archive.org/web/20120623040907/http://fas.org/spp/military/program/com/leasat.htm |archive-date=June 23, 2012 }}</ref> and were deployed like a [[Frisbee]].<ref name="Beginnings">{{cite web |last=Fisher |first=Jack |date=January 3, 2013 |title=Leasat Beginnings and Significance–Boris Subbotin |url=http://www.hughesscgheritage.com/leasat-beginnings-and-significance-dr-boris-t-subbotin/ |work=Our Space Heritage 1960–2000 }}</ref> The satellites are 30&nbsp;rpm [[Spin-stabilized satellite|spin-stabilized]] with a despun communications and antenna section. They were made with a solid rocket motor for initial perigee burn and [[hydrazine]] propellant for station keeping and spin stabilization. The communications systems offers a wideband UHF channel (500&nbsp;kHz bandwidth), six relay 25&nbsp;kHz channels, and five narrowband 5&nbsp;kHz channels.<ref name="hughes-boeing">{{cite web |title=First Satellite Designed for Space Shuttle Launch |work=Defense, Space & Security |publisher=Boeing |archive-url=https://web.archive.org/web/20091230151101/http://boeing.com/defense-space/space/bss/factsheets/government/leasat/leasat.html |archive-date=December 30, 2009 |url=http://boeing.com/defense-space/space/bss/factsheets/government/leasat/leasat.html }}</ref> This is in addition to the fleet broadcast frequency, which is in the military's X-band. The system was used by military customers in the US and later in Australia. Most of the satellites were retired in the 1990s, but one would remain operational until 2015. During the [[Gulf War|First Gulf War]], Leasat would be used for personal communications between Secretary of State [[James Baker]] and President [[George H. W. Bush]],<ref name="ott" /> but was more typically used by "mobile air, surface, subsurface, and fixed earth stations of the Navy, Marine Corps, Air Force, and Army."<ref name="hughes-boeing" />

Hughes was contracted to provide a worldwide communications system based on four satellites, one over the continental United States (CONUS), and one each over the [[Atlantic Ocean|Atlantic]], [[Pacific Ocean|Pacific]], and [[Indian Ocean|Indian]] oceans, spaced about 90 degrees apart.<ref name="fas" /> Five satellites were ordered, with one as a replacement. Also part of the contract were the associated control systems and ground stations. The lease contracts were typically for five-year terms, with the lessee having the opportunity to extend the lease or to purchase the equipment outright. The [[US Navy]] was the original lessee.

'''Leasat F1'''<nowiki/>'s launch was canceled just prior to lift-off, and '''F2''' became the first into orbit on August 30, 1984, aboard {{OV|Discovery}} on shuttle mission [[STS-41-D]]. F2 was largely successful, but its wideband receiver was out of commission after only four months.<ref name="ott" /> F1 was launched successfully on November 8, 1984, aboard [[STS-51-A]]. This was followed on April 12, 1985, by '''Leasat F3''' on [[STS-51-D]]. F3's launch was declared a failure when the satellite failed to start its maneuver to geostationary orbit once released from {{OV|Discovery|full=no}}. Attempts by Shuttle astronauts to activate F3 with a makeshift "flyswatter" were unsuccessful.<ref name="ott" /> The satellite was left in [[low Earth orbit]], and the Space Shuttle returned to Earth. This failure made front-page news in ''[[The New York Times]]''.<ref name="rescue">{{cite web |last=Fisher |first=Jack |date=April 23, 2013 |title=The Leasat Rescue Mission—Steve Dorfman |url=http://www.hughesscgheritage.com/the-leasat-rescue-mission-steve-dorfman/ |work=Our Space Heritage 1960–2000 }}</ref> Hughes had an insurance policy on the satellite, and so claimed a total loss for the spacecraft of about $200 million, an amount underwritten by numerous parties.

However, with another satellite planned to be launched, it was determined that a space walk by a subsequent Shuttle crew might be able to "wake" the craft. The best guess was that a switch had failed to turn on the satellite. A "bypass box" was hastily constructed, NASA was excited to offer assistance, the customer was supportive, and the insurance underwriters agreed to fund the first ever attempt at space salvage.<ref name="rescue" />

On August 27, 1985 {{OV|Discovery|full=no}} was again used to launch '''Leasat F4''', and during the same mission ([[STS-51-I]]) captured the 15,000&nbsp;lb stricken F3. Astronaut [[James van Hoften]] grappled and then {{Em|manually}} spun down the F3 satellite. After the bypass box was installed by van Hoften and [[William Frederick Fisher|Bill Fisher]],<ref name="winter1993">{{cite web |title=The LEASAT Program That Launched HCI Completes 13 Years Of Service |date=Winter 1993 |archive-url=https://web.archive.org/web/19990507015718/http://www.spaceway.com/uplink/archive/up964/leasat964.html |archive-date=May 7, 1999 |url=http://www.spaceway.com/uplink/archive/up964/leasat964.html |work=Uplink |publisher=Hughes Communications }}</ref> van Hoften manually spun the satellite up. Once released, the F3 successfully powered up, fired its perigee motor and obtained a geostationary orbit. (This scenario would play out again in 1992 with [[Intelsat 603]] and {{OV|Endeavour|full=nolink}}.) While F3 was now operational, Leasat F4 soon failed and was itself declared a loss after only 40 hours of RF communications.<ref name="ott" /><ref name="winter1993" />

The stricken F4 did not remain a complete failure. Data from F4's failure permitted the saving of F1 from a premature failure. Since all of the Leasats are spin-stabilized, they have a bearing that connects the non-rotating and rotating parts of the spacecraft. After F4's communication failure, it suffered a spin lock while attempting to jostle the communications payload: the spun and despun sections locked together.<ref name="ott" /> Remembering this second failure of F4, and with F1 beginning to wear out at the spin bearing, it was decided to "flip" F1 every six months to keep the payload in the sun.<ref name="ott" /> Thus F1 went on to operate smoothly for its remaining life and never encountered a locked despun section.

Leasat F4 was subsequently powered down and moved to a [[graveyard orbit]] with a large amount of station keeping fuel in reserve. This was fortuitous; when another satellite suffered a loss of its fuel ten years later, Hughes engineers pioneered the use of alternative propellants with Leasat F4. Long after its primary mission had failed, F4 was powered back on to test whether a satellite could be kept on station using nonvolatile propellants.<ref name="ott" /> F4 was used to perform numerous tests, including maneuvers with oxidizer for propulsion once the hydrazine ran out.

The fifth and last '''Leasat (F5)''', which was built as a spare, was successfully launched by {{OV|Columbia}} mission [[STS-32]] on January 9, 1990. The last active Leasat, it was officially decommissioned on September 24, 2015, at 18:25:13&nbsp;UTC.<ref>{{cite web |url=http://www.intelsat.com/blog/industry-news-blog/another-intelsat-satellite-serves-customers-for-more-than-25-years/ |title=Another Intelsat Satellite Serves Customers for More Than 25 Years |publisher=Intelsat |first=Sharyn |last=Nerenberg |date=January 24, 2015 |access-date=September 25, 2015 |archive-url=https://web.archive.org/web/20150926034550/http://www.intelsat.com/blog/industry-news-blog/another-intelsat-satellite-serves-customers-for-more-than-25-years/ |archive-date=September 26, 2015 }}</ref> F5 was one of the longest-serving and most successful commercial satellites. Towards the end of its 25-year life, F5 had been leased by the [[Australian Defence Force]] for UHF service.

{| class="wikitable sortable"
|+Syncom / Leasat satellites
|-
! Date
! Name
! [[International Designator|ID]]
! Launch vehicle
|-
| 1963-02-14
| Syncom 1 
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-004A 1963-004A]
| [[Delta B|Thor Delta B]]
|-
| 1963-07-26
| Syncom 2
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-031A 1963-031A]
| [[Delta B|Thor Delta B]]
|-
| 1964-08-19
| Syncom 3
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-047A 1964-047A]
| [[Delta D|Thor Delta D]]
|-
| 1984-11-10
| Syncom IV Leasat F1
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-093C 1984-093C]
| {{OV|Discovery}}, [[STS-51-A]]
|-
| 1984-08-31
| Syncom IV Leasat F2
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-113C 1984-113C]
| {{OV|Discovery|full=nolink}}, [[STS-41-D]] 
|-
| 1985-04-12
| Syncom IV Leasat F3 
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-028C 1985-028C]
| {{OV|Discovery|full=nolink}}, [[STS-51-D]]
|-
| 1985-08-29
| Syncom IV Leasat F4 
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-076D 1985-076D]
| {{OV|Discovery|full=nolink}}, [[STS-51-I]]
|-
| 1990-01-09
| Syncom IV Leasat F5 
| [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1990-002B 1990-002B]
| {{OV|Columbia|full=nolink}}, [[STS-32]]
|}

==See also==
* [[List of communications satellite firsts]]
* {{Annotated link|ATS-1}}
* {{Annotated link|John H. Rubel}}

==References==
{{Reflist|refs=

<ref name="ott">{{cite web |last=Fisher |first=Jack |date=November 2, 2015 |title=LEASAT F5, The Final Chapter-Andy Ott |url=http://www.hughesscgheritage.com/leasat-f5-the-final-chapter-andy-ott/ |work=Our Space Heritage 1960-2000}}</ref>

}}

== Further reading ==
* {{cite web  |title=Boeing. Satellite Development Center. Syncom. The world's first geosynchronous communications satellite |url=http://www.boeing.com/defense-space/space/bss/factsheets/376/syncom/syncom.html |archive-url=https://web.archive.org/web/20101111082736/http://www.boeing.com/defense-space/space/bss/factsheets/376/syncom/syncom.html |archive-date=November 11, 2010 |quote=For example, no transistor amplifiers existed, and transistors then didn't work well at frequencies above 70&nbsp;MHz. We had to get up to 10&nbsp;GHz. So we used a chain of diode frequency multipliers, or doublers. }}

== External links ==
* [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-031A Syncom 2 satellite description]
* NASA Goddard Space Flight center descriptions:
** [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-004A Syncom 1]
** [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-031A Syncom 2]
** [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-047A Syncom 3]

[[Category:1961 establishments in the United States]]
[[Category:1963 in spaceflight]]
[[Category:Communications satellites]]
[[Category:History of telecommunications]]
[[Category:NASA programs]]
[[Category:Satellite series]]
[[Category:Satellites in geosynchronous orbit]]