CREW 19/20 . ... ISS Flight Engineer, . ... From May 1991 to July 1992 he worked at JSC in Life Sciences Office and served on the Health Maintenance Facility Project related to the Hyperbaric and Respiratory Subsystems for Space Station Freedom. ... From July 1995 through July 1998, he served as Medical Operations Lead for the International Space Station. ... From July 1998 until selected as an astronaut candidate, Barratt served as lead crew surgeon for the first expedition crew to ISS. ...