Selected as an astronaut by the Canadian Space Agency in 1992, Dr. Williams participated in Neurolab, a 16-day mission in 1998, flying aboard the Space Shuttle Columbia. He and seven crewmembers served as both experiment subjects and operators for 26 life science experiments focused on the effects of microgravity on the brain and the nervous system.
Dr. Williams was appointed Director of NASA's Space and Life Sciences Directorate at the Johnson Space Center in Houston, Texas, and then Deputy Associate Administrator for Crew Health and Safety of the Office of Space Flight at NASA Headquarters, while he continued active astronaut training.
Dr. Williams has also participated in two underwater missions, one as Commander. The NEEMO missions assessed the potential of space-delivered tele-medicine as a way to deliver medical care to remote locations, important, as well, for the future of extended spaceflight.
In August 2007, Dr. Williams completed his second spaceflight as a mission specialist on STS-118, where he established a Canadian record of 17 hours and 47 minutes in three spacewalks accomplished in one mission, supporting construction of the International Space Station.
In all Dr. Dave Williams has flown more than 18 million kilometres and spent 28 days, 15 hours, 45 minutes and 33 seconds in space.