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STS-51-F Instrument Pointing System.jpg
Experiments in Challenger's payload bay
Mission typeAstronomical observations
COSPAR ID1985-063A
SATCAT no.15925
Mission duration7 days, 22 hours, 45 minutes, 26 seconds
Distance travelled5,284,350 kilometres (3,283,543 mi)
Orbits completed127
Spacecraft properties
SpacecraftSpace Shuttle Challenger
Launch mass114,693 kilograms (252,855 lb)
Landing mass98,309 kilograms (216,735 lb)
Payload mass16,309 kilograms (35,955 lb)
Crew size7
Start of mission
Launch dateJuly 29, 1985, 21:00:00 (1985-07-29UTC21Z) UTC
Launch siteKennedy LC-39A
End of mission
Landing dateAugust 6, 1985, 19:45:26 (1985-08-06UTC19:45:27Z) UTC
Landing siteEdwards Runway 23
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude312.1 kilometres (193.9 mi)
Apogee altitude321.1 kilometres (199.5 mi)
Inclination49.5 degrees
Period90.9 min
STS-51-F patch.svg STS-51-F crew.jpg
Front row (seated) L–R: Fullerton, Bridges, Back row (standing) L–R: England, Henize, Musgrave, Acton, Bartoe 

STS-51-F (formerly STS-26 & also known as Spacelab 2) was the 19th flight of NASA's Space Shuttle program and the eighth flight of Space Shuttle Challenger. It launched from Kennedy Space Center, Florida, on July 29, 1985, and landed just under eight days later on August 6.

While STS-51-F's primary payload was the Spacelab 2 laboratory module, the payload that received the most publicity was the Carbonated Beverage Dispenser Evaluation, which was an experiment in which both Coca-Cola and Pepsi tried to make their carbonated drinks available to astronauts.[1] A helium-cooled Infrared telescope (IRT) was also flown on this mission, and while it did have some problems, it observed 60% of the galactic plane in infrared light.[2][3]

During launch Challenger experienced multiple sensor failures in its RS-25 engines and had to perform an "Abort to Orbit" (ATO) emergency procedure. It is the only Shuttle mission to have carried out an abort after launching. As a result of the ATO, the mission was carried out at a slightly lower orbital altitude.


Position Crew member
Commander C. Gordon Fullerton Member of Red Team Member of Blue Team
Second and last spaceflight
Pilot Roy D. Bridges Jr. Member of Red Team
Only spaceflight
Mission Specialist 1 Karl G. Henize Member of Red Team
Only spaceflight
Mission Specialist 2 F. Story Musgrave Member of Blue Team
Second spaceflight
Mission Specialist 3 Anthony W. England Member of Blue Team
Only spaceflight
Payload Specialist 1 Loren W. Acton Member of Red Team
Only spaceflight
Payload Specialist 2 John-David F. Bartoe Member of Blue Team
Only spaceflight

Backup crew[edit]

Position Astronaut
Payload Specialist 1 George W. Simon Member of Red Team
First spaceflight
Payload Specialist 2 Dianne K. Prinz Member of Blue Team
First spaceflight

Crew seating arrangements[edit]

Seat[4] Launch Landing STS-121 seating assignments.png
Seats 1–4 are on the Flight Deck. Seats 5–7 are on the Middeck.
S1 Fullerton Fullerton
S2 Bridges Bridges
S3 Henize Henize
S4 Musgrave Musgrave
S5 England England
S6 Acton Acton
S7 Bartoe Bartoe

Crew notes[edit]

As with previous Spacelab missions, the crew was divided between two 12-hour shifts. Acton, Bridges and Henize made up the "Red Team" while Bartoe, England and Musgrave comprised the "Blue Team"; commander Fullerton could take either shift when needed.[5] Challenger carried two EMUs in the event of an emergency spacewalk, which would have been performed by England and Musgrave.[5]


Aborted launch attempt at T-3 seconds on July 12, 1985
The control panel of the Shuttle on the STS-51-F mission, showing the selection of the Abort-to-Orbit (ATO) option

STS-51-F's first launch attempt on July 12, 1985 was halted with the countdown at T−3 seconds after main engine ignition, when a malfunction of the number two RS-25 coolant valve caused the shutdown of all three main engines. Challenger launched successfully on its second attempt on July 29, 1985, at 17:00 EDT, after a delay of 1 hour 37 minutes due to a problem with the table maintenance block update uplink.

At 3 minutes 31 seconds into the ascent, one of the center engine's two high-pressure fuel turbopump turbine discharge temperature sensors failed. 2 minutes and 12 seconds later, the second sensor failed, causing the shutdown of the center engine. This was the only in-flight main-engine failure of the Space Shuttle program. Approximately 8 minutes into the flight, one of the same temperature sensors in the right engine failed, and the remaining right-engine temperature sensor displayed readings near the redline for engine shutdown. Booster Systems Engineer Jenny M. Howard acted quickly to command the crew to inhibit any further automatic RS-25 shutdowns based on readings from the remaining sensors, preventing the potential shutdown of a second engine and a possible abort mode that may have resulted in the loss of the vehicle and crew.[6]

The failed RS-25 resulted in an Abort to Orbit (ATO) trajectory, whereby the shuttle achieved a lower-than-planned orbital altitude. The plan had been for a 208 nautical miles (385 km) by 206 nautical miles (382 km) orbit,[7] but the mission was carried out at 143 nautical miles (265 km) by 109 nautical miles (202 km).[8]

Attempt Planned Result Turnaround Reason Decision point Weather go (%) Notes
1 12 Jul 1985, 3:30:00 pm scrubbed technical 12 Jul 1985, 3:29 pm ​(T-0:03) pad abort: malfunction in SSME #2 coolant valve shutdown of all three main engines[9][10]
2 29 Jul 1985, 5:00:00 pm success 17 days, 1 hour, 30 minutes 29 Jul 1985, 5:00 pm Launched after 1 hour 37 minute delay to resolve issue with table maintenance block update uplink. At T+343s, #1 SSME shut down leading to ATO (Abort to Orbit.) [8]

Mission summary[edit]

The Plasma Diagnostics Package (PDP) grappled by the Remote Manipulator System (RMS)
Space art for the Spacelab 2 mission, showing some of the various experiments in the payload bay
Tony England drinks soda in space
A view of the Sierra Nevada mountains and surroundings from Earth orbit, taken on the STS-51-F mission

STS-51-F's primary payload was the laboratory module Spacelab 2. A special part of the modular Spacelab system, the "igloo", which was located at head of a three-pallet train, provided on-site support to instruments mounted on pallets. The main mission objective was to verify performance of Spacelab systems, determine the interface capability of the orbiter, and measure the environment created by the spacecraft. Experiments covered life sciences, plasma physics, astronomy, high-energy astrophysics, solar physics, atmospheric physics and technology research. Despite mission replanning necessitated by Challenger's abort to orbit trajectory, the Spacelab mission was declared a success.

The flight marked the first time the ESA Instrument Pointing System (IPS) was tested in orbit. This unique pointing instrument was designed with an accuracy of one arcsecond. Initially, some problems were experienced when it was commanded to track the Sun, but a series of software fixes were made and the problem was corrected. In addition, Tony England became the second amateur radio operator to transmit from space during the mission.

Spacelab Infrared Telescope[edit]

The Spacelab Infrared Telescope (IRT) was also flown on the mission.[3] The IRT was a 15.2 cm aperture helium-cooled infrared telescope, observing light between wavelengths of 1.7 to 118 μm.[3] The experiment experienced some problems, it was thought heat emissions from the Shuttle corrupting long-wavelength data, but it still returned useful astronomical data.[3] Another problem was that a piece of mylar insulation broke loose and floated in the line-of-sight of the telescope.[3] IRT collected infrared data on 60% of the galactic plane.[2] (see also List of largest infrared telescopes) A later space mission that experienced a stray light problem from debris was Gaia astrometry spacecraft launch in 2013 by the ESA—the source of the stray light was later identified as the fibers of the sunshield, protruding beyond the edges of the shield.[11]

PDP, Cola etc[edit]

The Plasma Diagnostics Package (PDP), which had been previously flown on STS-3, made its return on the mission, and was part of a set of plasma physics experiments designed to study the Earth's ionosphere. During the third day of the mission, it was grappled out of the payload bay by the Remote Manipulator System and released for six hours.[12] During this time, Challenger maneuvered around the PDP as part of a targeted proximity operations exercise. The PDP was successfully grappled by the RMS and returned to the payload bay at the beginning of the fourth day of the mission.[12]

In a heavily publicized marketing experiment, astronauts aboard STS-51-F drank carbonated beverages from specially designed cans from Cola Wars competitors Coca-Cola and Pepsi.[13] According to Acton, after Coke developed its experimental dispenser for an earlier shuttle flight, Pepsi insisted to the Reagan administration that Coke should not be the first cola in space. The experiment was delayed until Pepsi could develop its own system, and the two companies' products were assigned to STS-51-F.[14]

Red Team tested Coke, and Blue Team tested Pepsi. As part of the experiment, each team was photographed with the cola logo. Acton said that while the sophisticated Coke system "dispensed soda kind of like what we’re used to drinking on Earth", the Pepsi can was a shaving cream can with the Pepsi logo on a paper wrapper, which "dispensed soda filled with bubbles" that was "not very drinkable".[14]

Acton said that when he gives speeches in schools, audiences are much more interested in hearing about the cola experiment than in solar physics.[14] Post-flight, the astronauts revealed that they preferred Tang, in part because it could be mixed on-orbit with existing chilled-water supplies, whereas there was no dedicated refrigeration equipment on board to chill the cans, which also fizzed excessively in microgravity.

In an experiment during the mission, thruster rockets were fired at a point over Tasmania and also above Boston to create two "holes" – plasma depletion regions – in the ionosphere. A worldwide group of geophysicists[15] collaborated with the observations made from Spacelab 2.


Challenger landed at Edwards Air Force Base, California, on August 6, 1985, at 12:45:26 p.m. PDT. Its rollout distance was 8,569 feet (2,612 m). The mission had been extended by 17 orbits for additional payload activities due to the Abort to Orbit. The orbiter arrived back at Kennedy Space Center on August 11, 1985.

Mission insignia[edit]

The mission insignia was designed by Houston artist Skip Bradley. Space Shuttle Challenger is depicted ascending toward the heavens in search of new knowledge in the field of solar and stellar astronomy, with its Spacelab 2 payload. The constellations Leo and Orion are shown in the positions they were in relative to the Sun during the flight. The nineteen stars indicate that the mission is the 19th shuttle flight.

Crew bios[edit]

C. Gordon Fullerton died on August 21, 2013, aged 76.[16]

Karl Gordon Henize died October 5, 1993 on an expedition to Mount Everest studying the effects of radiation from space.[17][18][19] (age 66)


One of the purposes of the mission was to test how suitable the Shuttle was for conducting infrared observations, and the IRT was operated on this mission.[20] However, the orbiter was found to have some draw-backs for infrared astronomy, and this led to later infrared telescopes being free-flying from the Shuttle orbiter.[20]

See also[edit]


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

  1. ^ 9 Weird Things That Flew on NASA's Space Shuttles | Final Shuttle Missions & NASA's Space Shuttle Souvenirs | NASA Shuttle Program |
  2. ^ a b "Archived copy of Infrared Astronomy From Earth Orbit". Archived from the original on December 21, 2016. Retrieved December 10, 2016.
  3. ^ a b c d e Kent, et al. – Galactic structure from the Spacelab infrared telescope (1992).
  4. ^ "STS-51F". Spacefacts. Retrieved February 26, 2014.
  5. ^ a b "Space Shuttle Mission STS-51F Press Kit" (PDF). NASA. 1985. Retrieved March 1, 2014.
  6. ^ Welch, Brian (August 9, 1985). "Limits to inhibit" (PDF). Space News Roundup. Houston, TX: NASA Lyndon B. Johnson Space Center. pp. 1, 3. Archived from the original (PDF) on March 22, 2009. Retrieved January 10, 2010.
  7. ^ "STS-51F Press Kit" (Press release). NASA. July, 1985. Check date values in: |date= (help)
  8. ^ a b Robert D. Legler; Floyd V. Bennett (September 2011). "Space Shuttle Missions Summary" (PDF). NASA Scientific and Technical Information Program Office. Archived from the original (PDF) on January 6, 2021. CS1 maint: discouraged parameter (link)
  9. ^ "STS-51F Launch attempt #1". NASA.
  10. ^ "Radio Coverage of STS-51F launch attempt 1". AP.
  11. ^ "STATUS OF THE GAIA STRAYLIGHT ANALYSIS AND MITIGATION ACTIONS". December 17, 2014. Retrieved January 1, 2015.
  12. ^ a b "STS-51F National Space Transportation System Mission Report". NASA Lyndon B. Johnson Space Center. September 1985. p. 2. Retrieved March 1, 2014.
  13. ^ Pearlman, Robert (May 31, 2001). "A Brief History of Space Marketing". Archived from the original on February 14, 2009. Retrieved March 24, 2014.
  14. ^ a b c "Loren Acton: The Coke and Pepsi Flight". Air & Space. November 18, 2010.
  15. ^ "Elizabeth A. Essex-Cohen Ionospheric Physics Papers". Retrieved February 17, 2016.
  16. ^ Robert Z. Pearlman (2013). "Gordon Fullerton, space shuttle test pilot, dies at 76". collectSPACE. Retrieved August 21, 2013.
  17. ^ Tom Read, Freefall, Pages 224-235 (Little Brown, Edition 1, 1998). ISBN 0-316-64303-3.
  18. ^ - The Independent Newspaper reporting on the Death of Karl Heinze, 23 October 1993
  19. ^ - NASA: Press Release: Former Astronaut Karl Henize dies on Mt. Everest Expedition, 8 October 1993
  20. ^ a b "The Space Review: From Skylab to Shuttle to the Smithsonian". Retrieved September 18, 2019.

External links[edit]