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Spacelab Module LM1 in Columbia's payload bay, serving as the United States Microgravity Laboratory
Mission typeMicrogravity research
COSPAR ID1995-056A Edit this at Wikidata
SATCAT no.23688
Mission duration15 days, 21 hours, 53 minutes, 16 seconds
Distance travelled10,600,000 kilometres (6,600,000 mi)
Orbits completed255
Spacecraft properties
SpacecraftSpace Shuttle Columbia
Payload mass15,250 kilograms (33,620 lb)
Crew size7
Start of mission
Launch date20 October 1995, 13:53:00 (1995-10-20UTC13:53Z) UTC
Launch siteKennedy LC-39B
End of mission
Landing date5 November 1995, 11:45:21 (1995-11-05UTC11:45:22Z) UTC
Landing siteKennedy SLF Runway 33
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude241 kilometres (150 mi)
Apogee altitude241 kilometres (150 mi)
Inclination39.0 degrees
Period89.7 min

Left to right - Seated: Sacco, Rominger, Lopez-Alegria; Standing: Coleman, Bowersox, Leslie, Thornton
← STS-69 (71)
STS-74 (73) →

STS-73 was a Space Shuttle program mission, during October–November 1995, on board the Space Shuttle Columbia. The mission was the second mission for the United States Microgravity Laboratory. The crew, who spent 16 days in space, were broken up into 2 teams, the red team and the blue team. The mission also included several Detailed Test Objectives or DTO's.


Position Astronaut
Commander Kenneth D. Bowersox
Third spaceflight
Pilot Kent V. Rominger
First spaceflight
Mission Specialist 1 Catherine G. Coleman
First spaceflight
Mission Specialist 2 Michael López-Alegría
First spaceflight
Mission Specialist 3 Kathryn C. Thornton
Fourth and last spaceflight
Payload Specialist 1 Fred W. Leslie
Only spaceflight
Payload Specialist 2 Albert Sacco Jr.
Only spaceflight

Backup crew[edit]

Position Astronaut
Payload Specialist 1 R. Glynn Holt
Only spaceflight
Payload Specialist 2 David H. Matthiesen
Only spaceflight

Mission highlights[edit]

Launch of STS-73

The second United States Microgravity Laboratory (USML-2) Spacelab mission was the prime payload on STS-73. The 16-day flight continued a cooperative effort of the U.S. government, universities and industry to push back the frontiers of science and technology in "microgravity", the near-weightless environment of space.

On October 26, through pre-recorded video, Mission Commander Ken Bowersox threw out the first pitch for Game 5 of the 1995 World Series between the Cleveland Indians and the Atlanta Braves from orbit.[1]

Some of the experiments carried on the USML-2 payload were suggested by the results of the first USML mission that flew aboard Columbia in 1992 during STS-50. The USML-1 mission provided new insights into theoretical models of fluid physics, the role of gravity in combustion and flame spreading, and how gravity affects the formation of semiconductor crystals. Data collected from several protein crystals grown on USML-1 enabled scientists to determine the molecular structures of those proteins.

USML-2 built on that foundation. Technical knowledge gained was incorporated into the mission plan to enhance procedures and operations. Where possible, experiment teams refined their hardware to increase scientific understanding of basic physical processes on Earth and in space, as well as to prepare for more advanced operations aboard the International Space Station and other future space programs.

The landing of STS-73.

USML-2 Flight controllers and experiment scientists directed science activities from NASA's Spacelab Mission Operations Control facility at the Marshall Space Flight Center. In addition, science teams at several NASA centers and universities monitored and supported operations of a number of experiments.

Other payloads on board included the Orbital Acceleration Research Experiment (OARE), Space Acceleration Measurement System (SAMS), Three Dimensional Microgravity Accelerometer (3DMA), Suppression of Transient Accelerations By Levitation Evaluation (STABLE) and the High-Packed Digital Television Technical Demonstration system.

Launch was originally scheduled for 25 September 1995 but endured six scrubbed launch attempts before its 20 October 1995 lift off. STS-73 and STS-61C both carry the distinction of being tied for the most scrubbed launches, each having launched on their seventh attempt.[2]

After the mission, five of the crew members, namely, Bowersox, Coleman, Thornton, Leslie, and Sacco appeared on the 13 February 1996 episode of Home Improvement, "Fear of Flying", on a segment of Tool Time.[3] It was Bowersox's second time on the show.

See also[edit]


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

  1. ^ "First Pitch From Space". www.nasa.gov. NASA. Retrieved 1 February 2022.
  2. ^ "Mission Archives". Retrieved 16 August 2010.
  3. ^ "Fear of Flying". www.imdb.com. 13 February 1996.

External links[edit]