STS-51-I

STS-51-I

van Hoften next to the crippled Syncom IV-3 (Leasat-3) satellite, during the mission's first EVA.
Names	Space Transportation System-20
Mission type	Satellites deployment Satellite repair
Operator	NASA
COSPAR ID	1985-076A
SATCAT no.	15992
Mission duration	7 days, 2 hours, 17 minutes, 42 seconds
Distance travelled	4,698,602 km (2,919,576 mi)
Orbits completed	112
Spacecraft properties
Spacecraft	Space Shuttle Discovery
Launch mass	118,981 kg (262,308 lb)
Landing mass	89,210 kg (196,670 lb)
Payload mass	17,540 kg (38,670 lb)[1]
Crew
Crew size	5
Members	Joe H. Engle Richard O. Covey James D. A. van Hoften John M. Lounge William F. Fisher
EVAs	2
EVA duration	11 hours, 46 minutes 1st EVA: 7 hours, 20 minutes 2nd EVA: 4 hours, 26 minutes
Start of mission
Launch date	August 27, 1985, 10:58:01 (August 27, 1985, 10:58:01) UTC (6:58:01 am EDT)
Launch site	Kennedy, LC-39A
Contractor	Rockwell International
End of mission
Landing date	September 3, 1985, 13:15:43 (September 3, 1985, 13:15:43) UTC (6:15:43 am PDT)
Landing site	Edwards, Runway 23
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	350 km (220 mi)
Apogee altitude	465 km (289 mi)
Inclination	28.45°
Period	92.00 minutes
Instruments
Physical Vapor Transport Organic Solid Experiment (PVTOS)
STS-51-I mission patch Back row: James D. A. van Hoften, John M. Lounge, William F. Fisher Front row: Joe H. Engle, Richard O. Covey Space Shuttle program ← STS-51-F (19) 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. During the mission, Discovery deployed three communications satellites 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.

EVA 1

• Personnel: Fisher and van Hoften
• Date: August 31, 1985 (≈12:10–19:10 UTC)^[2]
• Duration: 7 hours, 20 minutes

EVA 2

• Personnel: Fisher and van Hoften
• Date: September 1, 1985 (≈12:10–16:30 UTC)^[2]
• Duration: 4 hours, 26 minutes

Seat[2]	Launch	Landing	Seats 1–4 are on the flight deck. Seats 5–7 are on the mid-deck.
1	Engle
2	Covey
3	van Hoften	Fisher
4	Lounge
5	Fisher	van Hoften
6	Unused
7	Unused

Discovery launched at 6:58 a.m. 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,^[3] and the second because the backup orbiter computer failed and had to be replaced.^[4] The successful launch on August 27, 1985, took place just as an approaching 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 Hoften, John M. Lounge, and William F. Fisher, mission specialists. Their primary mission was to deploy three 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 Aussat-1, a multi-purpose spacecraft owned by Australia; ASC-1, owned and operated by the American Satellite Corporation (ASC); and Syncom IV-4 (Leasat-4), leased to the 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 orbits and became operational.

On the fifth day of the mission, astronauts Fisher and van 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 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. 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.

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.

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.^[5]

• 
  Deployment of Aussat-1
• 
  Deployment of ASC-1
• 
  Deployment of Syncom IV-4 (Leasat-4)

• List of human spaceflights
• List of Space Shuttle missions

• NASA mission summary Archived December 9, 2012, at the Wayback Machine
• STS-51I Video Highlights Archived July 18, 2012, at the Wayback Machine