(04/17/1998) --- STS-90 Mission Specialist Dafydd (Dave) Williams, M.D., with the Canadian Space Agency is assisted by NASA and USA closeout crew members immediately preceding launch for the nearly 17-day Neurolab mission. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. Seen behind Williams also in an orange launch and re-entry suit is Mission Specialist Richard Linnehan, D.V.M. Williams and six fellow crew members will shortly enter the orbiter at KSC's Launch Pad 39B, where the Space Shuttle Columbia will lift off during a launch window that opens at 2:19 p.m. EDT, April 17