STS-51-D Syncom IV-3 activation effort.jpg
The crew attempt to activate Syncom IV-3 via a "flyswatter" device attached to Discovery's Canadarm
Mission typeSatellite deployment
COSPAR ID1985-028A
SATCAT no.15641
Mission duration6 days, 23 hours, 55 minutes, 23 seconds
Distance travelled4,650,658 kilometres (2,889,785 mi)
Orbits completed110
Spacecraft properties
SpacecraftSpace Shuttle Discovery
Launch mass113,802 kilograms (250,891 lb)
Landing mass89,818 kilograms (198,014 lb)
Payload mass13,039 kilograms (28,747 lb)
Crew size7
EVA duration3 hours, 6 minutes
Start of mission
Launch dateApril 12, 1985, 13:59:05 (1985-04-12UTC13:59:05Z) UTC
Launch siteKennedy LC-39A
End of mission
Landing dateApril 19, 1985, 13:54:28 (1985-04-19UTC13:54:29Z) UTC
Landing siteKennedy SLF Runway 33
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude300 kilometres (160 nmi)
Apogee altitude452 kilometres (244 nmi)
Inclination28.5 degrees
Period94.4 minutes
EpochApril 14, 1985[1]
Sts-51-d-patch.png STS-51-D Crew March 1985.jpg
Back row L-R: Griggs, Walker, Garn
Front row: L-R: Bobko, Williams, Seddon, Hoffman. 

STS-51-D (formerly STS-23) was the 16th flight of NASA's Space Shuttle program, and the fourth flight of Space Shuttle Discovery.[2] The launch of STS-51-D from Kennedy Space Center (KSC), Florida, on April 12, 1985 was delayed by 55 minutes, after a boat strayed into the restricted Solid Rocket Booster (SRB) recovery zone. STS-51-D was the third shuttle mission to be extended.

On April 19, after a week-long flight, Discovery conducted the fifth shuttle landing at KSC. The shuttle suffered extensive brake damage and a ruptured tire during landing. This forced all subsequent shuttle landings to be done at Edwards Air Force Base, California, until the development and implementation of nose wheel steering made landings at KSC more feasible.


Position Astronaut
Commander Karol J. Bobko
Second spaceflight
Pilot Donald E. Williams
First spaceflight
Mission Specialist 1 M. Rhea Seddon
First spaceflight
Mission Specialist 2 S. David Griggs
Only spaceflight
Mission Specialist 3 Jeffrey A. Hoffman
First spaceflight
Payload Specialist 1 Charles D. Walker
Second spaceflight
Payload Specialist 2 Edwin J. 'Jake' Garn
Only spaceflight
Garn was a Republican Senator from Utah acting as a congressional
observer. He was the first sitting member of Congress in space.


  • Hoffman and Griggs – EVA 1
  • EVA 1 Start: April 16, 1985
  • EVA 1 End: April 16, 1985
  • Duration: 3 hours, 06 minutes

Crew seating arrangements

Seat[3] Launch Landing STS-121 seating assignments.png
Seats 1–4 are on the Flight Deck. Seats 5–7 are on the Middeck.
S1 Bobko Bobko
S2 Williams Williams
S3 Seddon Hoffman
S4 Griggs Griggs
S5 Hoffman Seddon
S6 Walker Walker
S7 Garn Garn

Mission summary

During STS-51-D, the shuttle crew deployed two communications satellites: Telesat-I (Anik C1) and Syncom IV-3 (also known as Leasat-3). Telesat-I was attached to a Payload Assist Module (PAM-D) motor and successfully deployed. Syncom IV-3, however, failed to initiate antenna deployment and spin-up, or ignite its perigee kick motor upon deployment. The mission was consequently extended by two days to ensure that the satellite's spacecraft sequencer start lever was in its proper position. Griggs and Hoffman performed an unscheduled EVA to attach homemade "Flyswatter" devices to the shuttle's Remote Manipulator System (RMS). Seddon then engaged the satellite's start lever using the RMS, but again the post-deployment sequence did not begin.[4] The satellite was subsequently retrieved, repaired and successfully redeployed during the STS-51-I mission later that year.

Discovery's other mission payloads included the Continuous Flow Electrophoresis System (CFES) III, which was flying for sixth time; two Shuttle Student Involvement Program (SSIP) experiments; the American Flight Echo-cardiograph (AFE); two Getaway Specials; a set of Phase Partitioning Experiments (PPE); an astronomical photography verification test; various medical experiments; and "Toys in Space," an informal study of the behavior of simple toys in a microgravity environment, with the results being made available to school students upon the shuttle's return.[5]

During the shuttle's landing at KSC on April 19, 1985, extensive brake damage was suffered, and a landing gear tire ruptured. This prompted future shuttle flights to land at Edwards Air Force Base, California, until effective nose wheel steering could be implemented to reduce risks during landing.

Wake-up calls

NASA began a tradition of playing music to astronauts during the Gemini program, 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.[6]

Flight Day Song Artist/Composer
Day 2 "Top of the World" The Carpenters
Day 3 "Rescue Aid Society" Song from the Disney film, The Rescuers


See also


 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

  1. ^ McDowell, Jonathan. "SATCAT". Jonathan's Space Pages. Retrieved March 24, 2014.
  2. ^ NASA. "STS-51D Press Kit" (PDF). Retrieved December 16, 2009.
  3. ^ "STS-51D". Spacefacts. Retrieved February 26, 2014.
  4. ^ Walker, Charles D. (April 14, 2005). "Oral History Transcript". NASA Johnson Space Center Oral History Project (Interview). Interviewed by Johnson, Sandra. |access-date= requires |url= (help)
  5. ^ "STS-51D". NASA. February 18, 2010. Retrieved January 16, 2018.
  6. ^ Fries, Colin (June 25, 2007). "Chronology of Wakeup Calls" (PDF). NASA. Retrieved August 13, 2007.

External links

  • NASA mission summary
  • STS-51D Video Highlights