Encyclopedia Astronautica

Crew: Bowersox, Coleman, Leslie, Lopez-Alegria, Rominger, Sacco, Thornton. Carried USML-2 for microgravity experiments (attached to Columbia).

Carried USML-2 for microgravity experiments (attached to Columbia). Payloads: United States Microgravity Laboratory (USML) 2, Orbital Acceleration Research Experiment (OARE).

Orbits of Earth: 256. Distance traveled: 10,621,670 km. Orbiter Liftoff Mass: 116,646 kg. Orbiter Mass at Landing: 104,398 kg. Payload to Orbit: 15,250 kg. Payload Returned: 15,250 kg. Landed at: Concrete runway 33 at Kennedy Space Center, Florida.

NASA Official Mission Summary:

Pad B
72nd Shuttle mission
18th flight OV-102
26th KSC landing
Extended mission
Kenneth D. Bowersox, Mission Commander (3rd)
Kent V. Rominger, Pilot (1st)
Kathryn C. Thornton, Payload Commander (4th)
Catherine G. Coleman, Science Mission Specialist (1st)
Michael E. Lopez-Alegria, Mission Specialist (1st)
Fred W. Leslie, Payload Specialist (1st)
Albert Sacco Jr., Payload Specialist (1st)
Orbiter Preps (move to):
VAB (temporary storage) - April 14, 1995
OPF - April 21, 1995
VAB - Aug. 22, 1995
Pad - Aug. 28, 1995


October 20, 1995, 9:53:00 a.m. EDT. A successful launch after six scrubs tied STS-73 with STS 61-C (Jan. 12-18, 1986) for most number of launch scrubs.

1). Liftoff originally set for Sept. 25 was scrubbed shortly after tanking began, when hydrogen leak was detected in main engine no. 1 main fuel valve. Valve replaced at pad.

2). Launch re-set for Oct. 5, but weather effects due to Hurricane Opal led to L-1 day decision to postpone launch one day to Oct. 6.

3). Oct. 6 launch attempt scrubbed prior to external tank loading when it was determined that hydraulic fluid had been inadvertently drained from hydraulic system 1 following the main engine no. 1 fuel valve replacement. Compressibility test demonstrated system was satisfactory for launch, and liftoff re-set to occur Oct. 7.

4). Launch attempt Oct. 7 scrubbed at T-20 seconds when master events controller 1 (MEC 1) failed to operate properly and mission managers determined it needed to be replaced. Launch reset for Oct. 14 was then

5). Re-scheduled to Oct. 15 to allow additional time to inspect the main engine oxidizer ducts as a result of finding a crack in a test engine oxidizer duct at Stennis. Also during this delay, a faulty general purpose computer 1 (GPC 1) had to be replaced.

6). Launch attempt Oct. 15 postponed at T-5 minutes due to low clouds and rain. Launch tentatively re-set to Oct. 19 pending successful Atlas launch Oct. 18; however, Atlas launch was delayed and STS-73 launch moved to Oct. 20. Countdown to liftoff Oct. 20 was delayed three minutes due to range computer glitch.


November 5, 1995, 6:45:21 a.m. EST, Runway 33, Kennedy Space Center, Fla. Rollout distance: 9,032 feet (2,753 meters). Rollout time: 55 seconds. Mission duration: 15 days, 21 hours, 52 minutes, 28 seconds. Landed revolution 256. Landing occurred on first opportunity at KSC. STS-73 became second longest Shuttle flight.

Mission Highlights:

STS-73 marked second flight of U.S. Microgravity Laboratory (USML) and built on foundation of its predecessor, which flew on Columbia during Mission STS-50 in 1992. Research during USML- 2 concentrated within same overall areas of USML-1, with many experiments flying for second time. Crew divided into two teams to work around the clock in 23-foot (seven-meter) long Spacelab module located in Columbia's payload bay.

Research was conducted in five areas: Fluid physics; materials science; biotechnology; combustion science; and commercial space processing. USML-2 activities were directed by NASA's Spacelab Mission Operations Control facility at Marshall Space Flight Center.

Experiments went smoothly. In some cases, results re-confirmed existing theories, while in other cases results were new and unique. Highlights included unprecedented results from the Surface Tension Driven Convection Experiment, which flew for second time and studied in great detail basic fluid mechanics and heat transfer of thermocapillary flows, motions created within fluids by non-uniform heating of their free surfaces. Oscillations observed on USML-2 samples had never been observed on Earth, and researchers controlling experiment from the ground were able to pinpoint when fluid flows transitioned from stable to unstable. Research has direct applications on Earth, in that unwanted fluid flows during melting and resolidifying can create defects in hightech crystals, metals, alloys and ceramics.

Flying for first time was Fiber Supported Droplet Combustion experiment. More than 25 droplets of variety of fuels were ignited, confirming theories about how fuels burn in microgravity. Results revealed larger droplet extension diameter - size of drop as it burns out - than are capable of being studied on Earth, with burning times 10 times longer. Data confirmed scientific predictions about burn rate and amount of fuel left over after fire goes out. This will allow investigators to refine theories and possibly develop new ones about byproducts such as soot and smog.

Five small potatoes were grown on-orbit from tubers in the Astroculture plant growth facility. USML-2 marked final test flight of Astroculture hardware, with unit set to become available commercially for sale or lease. Technologies incorporated in Astroculture hardware design already are finding application on Earth; for example, technology behind light-emitting diodes (LEDs) that provide high levels of light on-orbit within limited electrical power is finding its way into energy-efficient lighting systems for large-scale commercial plant nurseries. Successful on-orbit growth demonstrated Astroculture's usefulness as plant growth facility and showed edible foods could be grown in space.

Record number of Protein Crystal Growth (PCG) samples - around 1,500 - were flown on USML-2 and initial results indicated many had produced crystals which were further studied after landing. Other crystal growth experiments were equally successful. In the Crystal Growth Furnace, which flew for first time on USML- 1, a crystal was grown for first time as a liquid bridge to minimize contact with container wall, thus decreasing number of defects in crystal. Eight semiconductor crystals were grown, also a very thin crystal and two crystals which could lead to products such as computer chips that are faster and use less power than traditional computer chips.

Crew took time out from Spacelab work to tape ceremonial first pitch for Game Five of baseball World Series, marking first time the thrower was not actually in the ballpark for the pitch.

Orbiter Columbia performed without serious problems, with only notable glitch being two vernier thruster jets failing several times throughout mission; function was restored by cycling them on and off. Also, equipment failure at ground terminal for NASA's Tracking and Data Relay Communications (TDRS) satellites necessitated two extended communications outages between Columbia and Earth in order to perform repair.

AKA: Columbia.
First Launch: 1995.10.20.
Last Launch: 1995.11.05.
Duration: 15.91 days.

More... - Chronology...

Associated People
  • Sacco Sacco, Dr Albert Jr 'Al' (1949-) American chemical engineer payload specialist astronaut. Flew on STS-73. More...
  • Leslie Leslie, Dr Fred Weldon (1951-) American meteorologist payload specialist astronaut. Flew on STS-73. More...
  • Thornton Thornton, Dr Kathryn Ryan Cordell 'Kathy' (1952-) American physicist mission specialist astronaut. Flew on STS-33, STS-49, STS-61, STS-73. More...
  • Rominger Rominger, Kent Vernon (1956-) American test pilot astronaut. Flew on STS-73, STS-80, STS-85, STS-96, STS-100. More...
  • Bowersox Bowersox, Kenneth Duane 'Ken' (1956-) American test pilot astronaut. Flew on STS-50, STS-61, STS-73, STS-82, ISS EO-6. More...
  • Lopez-Alegria Lopez-Alegria, Michael Eladio 'LA' (1958-) Spanish-American test pilot mission specialist astronaut. Flew on STS-73, STS-92, STS-113, ISS EO-14. More...
  • Coleman Coleman, Dr Catherine Grace 'Cady' (1960-) American materials scientist mission specialist astronaut. Flew on STS-73, STS-93, ISS EO-26. US Air Force engineer. More...

Associated Countries
Associated Spacecraft
  • Columbia American manned spaceplane. 28 launches, 1981.04.12 (STS-1) to 2003.01.16 (STS-107). Columbia, the first orbiter in the Shuttle fleet, was named after the sloop that accomplished the first American circumnavigation of the globe. More...

See also
Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • NASA Houston American agency overseeing development of rockets and spacecraft. Houston, Houston, USA. More...

Associated Programs
  • STS The Space Transportation System (Space Shuttle) was conceived originally as a completely reusable system that would provide cheap, routine access to space and replace all American and civilian military launch vehicles. Crippled by technological overreach, political compromise, and budget limitations, it instead ended up costing more than the expendable rockets it was to have replaced. STS sucked the money out of all other NASA projects for half a century. The military abandoned its use after the Challenger shuttle explosion in the 1980's. More...

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...

STS-73 Chronology

1995 October 20 - . 13:53 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39B. LV Family: Shuttle. Launch Vehicle: Shuttle. LV Configuration: Space Shuttle STS-73.
  • STS-73 - . Call Sign: Columbia. Crew: Bowersox; Coleman; Leslie; Lopez-Alegria; Rominger; Sacco; Thornton. Payload: Columbia F18 / Spacelab LM / EDO. Mass: 15,250 kg (33,620 lb). Nation: USA. Related Persons: Bowersox; Coleman; Leslie; Lopez-Alegria; Rominger; Sacco; Thornton. Agency: NASA Houston. Program: STS. Class: Manned. Type: Manned spaceplane. Flight: STS-73. Spacecraft: Columbia. Duration: 15.91 days. Decay Date: 1995-11-05 . USAF Sat Cat: 23688 . COSPAR: 1995-056A. Apogee: 241 km (149 mi). Perigee: 241 km (149 mi). Inclination: 39.0000 deg. Period: 89.70 min. Summary: Carried USML-2 for microgravity experiments (attached to Columbia). Payloads: United States Microgravity Laboratory (USML) 2, Orbital Acceleration Research Experiment (OARE)..

1995 November 5 - .
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