(07/01/1997) --- STS-94 Mission Specialist Donald A. Thomas prepares to enter the Space Shuttle Columbia at Launch Pad 39A in preparation for launch. He has flown on STS-83, STS-70 and STS-65. He holds a doctorate in materials science and has been the Principal Investigator for a Space Shuttle crystal growth experiment. Because of his background in materials science, Thomas will be concentrating his efforts during the Red shift on the five experiments in this discipline in the Large Isothermal Furnace. He also will work on the ten materials science investigations in the Electromagnetic Containerless Processing Facility and four that will be measuring the effects of microgravity and motion in the orbiter on the experiments. Thomas and six fellow crew members will lift off during a launch window that opens at 1:50 p.m. EDT, July 1. The launch window will open 47 minutes early to improve the opportunity to lift off before Florida summer rain showers reach the space center