Andrew "Andy" Sydney Withiel Thomas, AO (born 18 December 1951 in Adelaide, South Australia) is an Australian and American aerospace engineer and a NASA astronaut. He has dual nationality; he became a U.S. citizen in December 1986, hoping to gain entry to NASA's astronaut program. 

Thomas was selected by NASA in March 1992 and reported to the Johnson Space Center in August 1992.

In August 1993, following one year of training, he was appointed a member of the NASA Astronaut Corps and was qualified for an assignment as a mission specialist on Space Shuttle flight crews.

While awaiting space flight assignment, Thomas supported shuttle launch and landing operations as an Astronaut Support Person (ASP) at the Kennedy Space Center.

He also provided technical support to the Space Shuttle Main Engine project, the Solid Rocket Motor project and the External Tank project at the Marshall Space Flight Center. In June 1995, Thomas was named as payload commander for STS-77 and flew his first flight in space on Endeavour in May 1996.

Although Paul D. Scully-Power had entered orbit as an oceanographer in 1985, Thomas was the first Australia-born professional astronaut to enter space. 

According to en.wikipedia