Astronaut Kathryn Thornton, payload commander for the STS-73 mission, attired in a high fidelity training version of the Extravehicular Mobility Unit (EMU) space suit, prepares to go underwater in the Johnson Space Center’s (JSC) Weightless Environment Training Facility (WET-F). The STS-73 mission was the second flight of the United States Microgravity Laboratory (USML-2), managed by scientists and engineers from the Marshall Space Flight Center.