S95-09132 (27 Apr. 1995) --- As he watches one his STS-73 crew mates rappel from the top of a ?troubled Shuttle,? astronaut Kenneth D. Bowersox, mission commander, prepares to participate in an emergency egress training session in the Johnson Space Center?s (JSC) Systems Integration Facility. Five astronauts and two payload specialists from the private sector will fly aboard the Space Shuttle Columbia later this year to support the United States Microgravity Laboratory (USML-2) mission.