Editing Syncom (section)

== 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 and called HS 381 by the manufacturer.<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]]
|}