During
graduate school, Reilly was selected to participate in the 1977–1978 scientific expedition to
Marie Byrd Land,
West Antarctica, as a research scientist specializing in stable isotope
geochronology. In 1979, he started work as an exploration geologist with
Santa Fe Minerals, in Dallas. From 1980 to the time he was selected for the astronaut program, Reilly was employed as an oil and gas exploration geologist for
Enserch Exploration, in Dallas, rising to the position of Chief Geologist of the Offshore Region. At the same time, he was involved in applying new imaging technology for industrial applications in deep water engineering projects and biological research. Reilly spent approximately 22 days in deep submergence vehicles operated by
Harbor Branch Oceanographic Institution and the
U.S. Navy. NASA selected Reilly for the astronaut program in December 1994. He reported to the
Johnson Space Center in March 1995 and completed a year of training and evaluation, and qualified for flight assignment as a mission specialist. Initially, he was assigned to work technical issues for the Astronaut Office Computer Support Branch. Reilly flew on
STS-89 (
Endeavour) in 1998,
STS-104 (
Atlantis) in 2001 and
STS-117 (
Atlantis) in 2007. He has logged over 850 hours in space, including five spacewalks (3 on STS-104, 2 on STS-117) totaling 30 hours and 43 minutes. He has worked both on the
ISS and
Mir space stations. Reilly was next assigned as the Astronaut Office lead on Shuttle training. Concurrent with his crew assignment he is designated as Payloads and Procedures Operations lead for the Astronaut Office ISS Branch. From January 2010 to May 2014, Reilly worked as the
American Public University System's Dean of the School of Science and Technology. In January 2018, U.S. President
Donald Trump nominated Reilly to be the director of the
U.S. Geological Survey. The
U.S. Senate confirmed him in April 2018. After leaving government service in 2020, Reilly later joined defense contractor
Booz Allen Hamilton the following year as an executive adviser. ==Organizations==