View source for STS-51-I

{{Short description|1985 American crewed spaceflight to Syncom IV-3}}
{{distinguish|STS-51-L}}
{{Use American English|date=January 2014}}
{{Use mdy dates|date=October 2022}}
{{Infobox spaceflight
| name               = STS-51-I
| names_list         = [[Space Transportation System]]-20
| image              = STS-51-I SYNCOM IV-3 EVA by James van Hoften.jpg
| image_caption      = van&nbsp;Hoften next to the crippled Syncom IV-3 (Leasat-3) satellite, during the mission's first EVA.
| mission_type       = Satellites deployment<br />Satellite repair
| operator           = [[NASA]]
| mission_duration   = {{time interval|August 27, 1985, 10:58:01|September 3, 1985, 13:15:43|show=dhms|sep=,}}
| distance_travelled = {{cvt|4698602|km}}
| orbits_completed   = 112
| spacecraft         = {{OV|103}}
| launch_mass        = {{cvt|118981|kg}}
| landing_mass       = {{cvt|89210|kg}}
| payload_mass       = {{cvt|17540|kg}}<ref>{{cite web|title=STS-51-I Press Kit|date=February 11, 2015 |url=https://www.nasa.gov/wp-content/uploads/2023/05/sts-51i-press-kit.pdf?emrc=d890cd|publisher=NASA}} {{PD-notice}}</ref>
| crew_size          = 5
| crew_members       = {{Unbulleted list|[[Joe Engle|Joe H. Engle]]|[[Richard O. Covey]]|[[James van Hoften|James D. A. van&nbsp;Hoften]]|[[John M. Lounge]]|[[William Frederick Fisher|William F. Fisher]]}}
| crew_EVAs          = 2
| crew_EVA_duration  = {{Unbulleted list
   | 11&nbsp;hours, 46&nbsp;minutes
   | {{small|1st&nbsp;EVA: 7&nbsp;hours, 20&nbsp;minutes}}
   | {{small|2nd&nbsp;EVA: 4&nbsp;hours, 26&nbsp;minutes}}
   }}
| launch_date        = {{Start date text|August 27, 1985, 10:58:01|timezone=yes}}{{nbsp}}[[Coordinated Universal Time|UTC]] (6:58:01{{nbsp}}am{{nbsp}}[[Eastern Daylight Time|EDT]])
| launch_site        = [[Kennedy Space Center|Kennedy]], [[Kennedy Space Center Launch Complex 39A|LC-39A]]
| launch_contractor  = [[Rockwell International]]
| landing_date       = {{End date text|September 3, 1985, 13:15:43|timezone=yes}}{{nbsp}}UTC (6:15:43{{nbsp}}am{{nbsp}}[[Pacific Daylight Time|PDT]])
| landing_site       = [[Edwards Air Force Base|Edwards]], Runway{{nbsp}}23
| orbit_reference    = [[Geocentric orbit]]
| orbit_regime       = [[Low Earth orbit]]
| orbit_periapsis    = {{cvt|350|km}}
| orbit_apoapsis     = {{cvt|465|km}}
| orbit_inclination  = 28.45°
| orbit_period       = 92.00 minutes
| apsis              = gee
| instruments        = Physical Vapor Transport Organic Solid Experiment (PVTOS)
| insignia           = Sts-51-i-patch.png
| insignia_caption   = STS-51-I mission patch
| crew_photo         = STS-51-I crew NASA.jpg
| crew_photo_caption = Back row: [[James van&nbsp;Hoften|James D. A. van&nbsp;Hoften]], [[William Frederick Fisher|William F. Fisher]]<br />Front row: [[Joe Engle|Joe H. Engle]], [[Richard O. Covey]], [[John M. Lounge]]
| programme          = [[Space Shuttle program]]
| previous_mission   = [[STS-51-F]] (19)
| next_mission       = [[STS-51-J]] (21)
}}

'''STS-51-I''' was the 20th mission of [[NASA]]'s [[Space Shuttle]] program and the sixth flight of [[Space Shuttle Discovery|Space Shuttle ''Discovery'']]. During the mission, ''Discovery'' deployed three [[communications satellite]]s into orbit. The mission launched from [[Kennedy Space Center]], [[Florida]], on August 27, 1985, and landed at [[Edwards Air Force Base]], [[California]], on September 3, 1985.

== Crew ==
{{Spaceflight crew
| terminology = Astronaut
| position1   = Commander
| crew1_up    = [[Joe Engle|Joe H. Engle]]
| flights1_up = Second and last
| position2   = Pilot
| crew2_up    = [[Richard O. Covey]]
| flights2_up = First
| position3   = Mission Specialist 1
| crew3_up    = [[James van Hoften|James D. A. van&nbsp;Hoften]]
| flights3_up = Second and last
| position4   = Mission Specialist 2<br />Flight Engineer
| crew4_up    = [[John M. Lounge]]
| flights4_up = First
| position5   = Mission Specialist 3
| crew5_up    = [[William Frederick Fisher|William F. Fisher]]
| flights5_up = Only
}}

=== Spacewalks ===
;EVA 1
* '''Personnel''': Fisher and van&nbsp;Hoften
* '''Date''': August 31, 1985 (≈12:10–19:10 UTC)<ref name="spacefacts" />
* '''Duration''': 7&nbsp;hours, 20&nbsp;minutes
;EVA 2
* '''Personnel''': Fisher and van&nbsp;Hoften
* '''Date''': September 1, 1985 (≈12:10–16:30 UTC)<ref name="spacefacts" />
* '''Duration''': 4&nbsp;hours, 26&nbsp;minutes

=== Crew seat assignments ===
{| class="wikitable" style="text-align:center"
! Seat<ref name="spacefacts">{{Cite web |title=STS-51I |url=http://spacefacts.de/mission/english/sts-51i.htm |access-date=February 26, 2014 |publisher=Spacefacts}}</ref>
! Launch
! Landing
|rowspan=8| [[File:Space Shuttle seating plan.svg|150px]]<br />Seats 1–4 are on the flight deck.<br />Seats 5–7 are on the mid-deck.
|-
! 1
|colspan=2| Engle
|-
! 2
|colspan=2| Covey
|-
! 3
| van&nbsp;Hoften
| Fisher
|-
! 4
|colspan=2| Lounge
|-
! 5
| Fisher
| van&nbsp;Hoften
|-
! 6
|colspan=2 style="background-color:lightgray"| ''Unused''
|-
! 7
|colspan=2 style="background-color:lightgray"| ''Unused''
|}

== Launch ==
{{LaunchAttempt
| date1           = 1985-08-24, 08:38:00
| result1         = Scrubbed
| reason1         = Weather
| decision_date1  = 1985-08-24, 09:06:00
| decision_clock1 = −00:05:00
| weathergo1      = 
| notes1          = Thunderstorms in the KSC area and a ship entering the SRB recovery area
| date2           = 1985-08-25, 07:57:00
| result2         = Scrubbed
| reason2         = Technical
| decision_date2  = 1985-08-25, 08:11:00
| decision_clock2 = −00:09:00 hold
| weathergo2      = 
| notes2          = Computer failure
| date3           = 1985-08-27, 06:58:01
| result3         = Success
| reason3         = 
| decision_date3  = 
| decision_clock3 = 
| weathergo3      = 
| notes3          = Launch delayed 3 minutes, 1 second for weather and ship in entering SRB recovery area.
}}

== Mission summary ==
''Discovery'' launched at 6:58 a.m. [[Eastern Time Zone|EDT]] on August 27, 1985. Two earlier launch attempts, one on August 24 and another on August 25, were scrubbed – the first because of poor weather,<ref>{{Cite news |last=O'Toole |first=Thomas |date=1985-08-24 |title=Rain Delays Discovery's Liftoff |url=https://www.washingtonpost.com/archive/politics/1985/08/25/rain-delays-discoverys-liftoff/223c11b9-1a7c-4fda-8d48-95dac276d1a5/ |access-date=2024-11-16 |work=The Washington Post |issn=0190-8286}}</ref> and the second because the backup orbiter computer failed and had to be replaced.<ref>{{Cite news |last=O'Toole |first=Thomas |date=1985-08-26 |title=Computer Failure Grounds Shuttle |url=https://www.washingtonpost.com/archive/politics/1985/08/26/computer-failure-grounds-shuttle/aa30cb72-0c2e-4a4c-8d5f-2651a4f2b43f/ |access-date=2024-11-16 |work=The Washington Post |issn=0190-8286}}</ref> The successful launch on August 27, 1985, took place just as an approaching [[thunderstorm|storm]] front reached the launch pad area.

The five-man STS-51-I crew included Joe H. Engle, commander; Richard O. Covey, pilot; and James D. A. van&nbsp;Hoften, John M. Lounge, and William F. Fisher, mission specialists. Their primary mission was to deploy three [[Communications satellite|commercial communications satellites]] and retrieve and repair the [[Syncom]] IV-3 (Leasat-3) satellite, which had been deployed during the [[STS-51-D]] mission in April 1985, but had malfunctioned. In addition, a mid-deck materials processing experiment, the Physical Vapor Transport Organic Solid Experiment (PVTOS), was flown aboard ''Discovery''.

The three communications satellites were [[Optus (satellite)|Aussat-1]], a multi-purpose spacecraft owned by [[Australia]]; ASC-1, owned and operated by the [[American Satellite Corporation]] (ASC); and Syncom IV-4 ([[Syncom|Leasat-4]]), leased to the [[United States Department of Defense|Department of Defense]] (DoD) by its builder, [[Hughes Space and Communications]]. Both Aussat-1 and ASC-1 were deployed on the day of the launch, August 27, 1985. Syncom IV-4 (Leasat-4) was deployed two days later. All three achieved their planned [[geosynchronous orbit]]s and became operational.

On the fifth day of the mission, astronauts Fisher and van&nbsp;Hoften began repair efforts on the malfunctioning Syncom IV-3, following a successful rendezvous maneuver by ''Discovery''. The effort was slowed by a problem with the Remote Manipulator System ([[Canadarm]]) elbow joint. After a second EVA by Fisher and van&nbsp;Hoften, the satellite's control lever was repaired, permitting commands from the ground to activate the spacecraft's systems and eventually send it into its proper geosynchronous orbit. The two EVAs lasted a total of 11 hours and 46 minutes.

''Discovery'' landed on Runway 23 at [[Edwards Air Force Base]] at 6:16 a.m. [[Pacific Time Zone|PDT]] on September 3, 1985. The flight lasted a total of 7 days, 2 hours, 18 minutes and 42 seconds, during which the shuttle completed 112 orbits of the [[Earth]].

== Mission insignia ==
The insignia depicts an American [[bald eagle]], trailing red and white stripes, and pushing a boundary layer forward. The 19 stars, along with the eagle, are references to the 20th shuttle mission (with the eagle representing the orbiter and thus being the 20th "star"). Lining the patch are the surnames of the crew members.

== Wake-up calls ==
NASA began a tradition of playing music to astronauts during the [[Project Gemini]], and first used music to wake up a flight crew during [[Apollo 15]]. Each track is specially chosen, often by the astronauts' families, and usually has a special meaning to an individual member of the crew, or is applicable to their daily activities.<ref name="chronology">{{cite news|first=Colin|last=Fries|title=Chronology of Wakeup Calls|date=June 25, 2007|publisher=NASA|url=https://history.nasa.gov/wakeup%20calls.pdf|access-date=August 13, 2007|archive-date=December 20, 2023|archive-url=https://web.archive.org/web/20231220093919/https://history.nasa.gov/wakeup%20calls.pdf|url-status=dead}} {{PD-notice}}</ref>

{| class="wikitable"
|-
! Flight Day
! Song
! Artist/Composer
|-
| Day 2
| "[[Waltzing Matilda]]"<ref>Chosen to waken the crew as they passed over [[Australia]].</ref>
| [[Banjo Paterson]]
|-
| Day 3
| "[[Over the Rainbow]]"
| [[Judy Garland]]
|-
| Day 4
| "[[I Saw the Light (Hank Williams song)|I Saw the Light]]"
| [[Willie Nelson]]
|-
| Day 5
| "[[I Get Around]]"
| [[Beach Boys]]
|-
| Day 6
| "[[Lucky Old Sun]]"
| [[Willie Nelson]]
|-
| Day 7
| "[[Stormy Weather (song)|Stormy Weather]]"<ref>Chosen due to [[Hurricane Elena]], which had been observed earlier from Discovery.</ref>
| [[Willie Nelson]]
|-
| Day 8
| "[[Living in the USA]]"
| [[Linda Ronstadt]]
|}

== Gallery ==
<gallery heights="160">
File:STS-51-I Launch.jpg|Launch of Space Shuttle Discovery
File:STS-51-I AUSSAT 1 deployment.jpg|Deployment of Aussat-1
File:STS-51-I ASC-1 deployment.jpg|Deployment of ASC-1
File:STS-51-I SYNCOM IV-4 deployment.jpg|Deployment of Syncom IV-4 (Leasat-4)
File:Space Shuttle Discovery Lands at Edwards Air Force Base.jpg|Space Shuttle Discovery Landing
</gallery>

== See also ==
{{Portal|Spaceflight}}
* [[List of human spaceflights]]
* [[List of Space Shuttle missions]]

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

== External links ==
* [http://science.ksc.nasa.gov/shuttle/missions/ NASA mission summary] {{Webarchive|url=https://web.archive.org/web/20121209083933/http://science.ksc.nasa.gov/shuttle/missions/ |date=December 9, 2012 }}
* [http://www.nss.org/resources/library/shuttlevideos/shuttle20.htm STS-51I Video Highlights] {{Webarchive|url=https://web.archive.org/web/20120718061547/http://www.nss.org/resources/library/shuttlevideos/shuttle20.htm |date=July 18, 2012 }}

{{Space Shuttle Discovery}}
{{All U.S. Space Shuttle Missions}}
{{Orbital launches in 1985}}

[[Category:Space Shuttle missions]]
[[Category:Edwards Air Force Base]]
[[Category:1985 in spaceflight]]
[[Category:1985 in the United States]]
[[Category:Spacecraft launched in 1985]]
[[Category:Spacecraft which reentered in 1985]]
[[Category:Satellite servicing missions]]