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STS 83



The primary payload on STS 83 was the Microgravity Science Laboratory (MSL), a collection of microgravity experiments housed inside a European Spacelab. First flight of the MSL was cut short due to concerns about one of three fuel cells, marking only the third time in Shuttle program history a mission ended early. (STS-2, 1981 and STS-44, 1991 were the other two times). Fuel cell No. 2 had shown some erratic readings during prelaunch startup, but was cleared to fly after additional checkout and test. Shortly after on-orbit operations began, the fuel cell no. 2 substack no. 3 differential voltage began trending upward. There are three fuel cells on each orbiter, each containing three substacks made up of two banks of 16 cells. In one substack of fuel cell no. 2, the difference in output voltage between the two banks of cells was increasing. The fuel cells use a reaction of liquid hydrogen and liquid oxygen to generate electricity and produce drinking water. Although one fuel cell produces enough electricity to conduct on-orbit and landing operations, Shuttle flight rules require all three to be functioning well to ensure crew safety and provide sufficient backup capability during reentry and landing.

When a purge failed to halt the upward trend, the fuel cell was shut down. Additional purges and other measures failed to correct the anomaly, and around 10 a.m., April 6, the Mission Management Team ordered the mission to end early. Fuel cell no. 2 was shut down for good later that afternoon and safed.

The crew was able to conduct some science in the MSL-1 Spacelab module despite the early return. Work was performed in the German electromagnetic levitation furnace facility (TEMPUS) on an experiment called Thermophysical Properties of Undercooled Metallic Melts. This experiment studies the amount of undercooling that can be achieved before solidification occurs. Another experiment performed was the Liquid-Phase Sintering II experiment in the Large Isothermal Furnace. This investigation uses heat and pressure to test theories about how the liquefied component bonds with the solid particles of a mixture without reaching the melting point of the new alloy combination.

Also conducted were two fire-related experiments. The Laminar Soot Processes experiment allowed scientists to observe for the first time the concentration and structure of soot from a fire burning in microgravity. The Structure of Flame Balls at Low Lewis-number experiment completed two runs. This experiment is designed to determine under what conditions a stable flame ball can exist, and if heat loss is responsible in some way for the stablilization of the flame ball during burning.

A decision to refly the mission in its entirety was made by the Mission Management Team in the days following Columbia's return. The reflight was first designated STS-83R and then renamed STS-94.

Alternate Names

  • 24755
  • STS83

Facts in Brief

Launch Date: 1997-04-04
Launch Vehicle: Shuttle
Launch Site: Cape Canaveral, United States

Funding Agency

  • NASA-Office of Space Flight (United States)


  • Life Science
  • Human Crew

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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