van Hoften next to the crippled Syncom IV-3 (Leasat-3) satellite, during the mission's first EVA.
NamesSpace Transportation System-20
Mission typeSatellites deployment
Satellite repair
COSPAR ID1985-076A Edit this at Wikidata
SATCAT no.15992
Mission duration7 days, 2 hours, 17 minutes, 42 seconds (achieved)
Distance travelled4,698,602 km (2,919,576 mi)
Orbits completed112
Spacecraft properties
SpacecraftSpace Shuttle Discovery
Launch mass118,981 kg (262,308 lb)
Landing mass89,210 kg (196,670 lb)
Payload mass17,540 kg (38,670 lb)[1]
Crew size5
EVA duration11 hours, 46 minutes
First: 7 hours, 20 minutes
Second: 4 hours, 26 minutes
Start of mission
Launch dateAugust 27, 1985, 10:58:01 UTC
RocketSpace Shuttle Discovery
Launch siteKennedy Space Center, LC-39A
ContractorRockwell International
End of mission
Landing dateSeptember 3, 1985, 13:15:43 UTC
Landing siteEdwards Air Force Base,
Runway 23
Orbital parameters
Reference systemGeocentric orbit
RegimeLow Earth orbit
Perigee altitude350 km (220 mi)
Apogee altitude465 km (289 mi)
Period92.00 minutes
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
← 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.


Position Astronaut
Commander Joe H. Engle
Second and last spaceflight
Pilot Richard O. Covey
First spaceflight
Mission Specialist 1 James D. A. van Hoften
Second and last spaceflight
Mission Specialist 2 John M. Lounge
First spaceflight
Mission Specialist 3 William F. Fisher
Only spaceflight


Crew seating arrangements

Seat[2] Launch Landing
Seats 1–4 are on the Flight Deck. Seats 5–7 are on the Middeck.
S1 Engle Engle
S2 Covey Covey
S3 van Hoften Fisher
S4 Lounge Lounge
S5 Fisher van Hoften


Attempt Planned Result Turnaround Reason Decision point Weather go (%) Notes
1 24 Aug 1985, 10:55:00 am scrubbed weather  ​(T-5:00)
2 25 Aug 1985, 10:55:00 am scrubbed 1 day, 0 hours, 0 minutes technical number 5 computer failure
3 27 Aug 1985, 10:58:01 am success 2 days, 0 hours, 3 minutes launch delayed three minutes, one second for weather and ship in entering SRB recovery area

Mission summary

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, and the second because the backup orbiter computer failed and had to be replaced. 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.

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.[3]

Flight Day Song Artist/Composer
Day 2 "Waltzing Matilda"[4] Banjo Paterson
Day 3 "Over the Rainbow" Judy Garland
Day 4 "I Saw the Light" Willie Nelson
Day 5 "I Get Around" Beach Boys
Day 6 "Lucky Old Sun" Willie Nelson
Day 7 "Stormy Weather"[5] Willie Nelson
Day 8 "Living in the USA" Linda Ronstadt


See also


  1. ^ "STS-51-I Press Kit" (PDF). NASA. February 11, 2015. Public Domain This article incorporates text from this source, which is in the public domain.
  2. ^ "STS-51I". Spacefacts. Retrieved February 26, 2014.
  3. ^ Fries, Colin (June 25, 2007). "Chronology of Wakeup Calls" (PDF). NASA. Archived from the original (PDF) on December 20, 2023. Retrieved August 13, 2007. Public Domain This article incorporates text from this source, which is in the public domain.
  4. ^ Chosen to waken the crew as they passed over Australia.
  5. ^ Chosen due to Hurricane Elena, which had been observed earlier from Discovery.