His space flights include the Atlantis mission in May 2000 to construct the International Space Station (ISS) and install equipment and supplies. In March 2001 he became a member of the second resident crew on the ISS, transported there on the space shuttle Discovery for a four-month stay. He has logged 201 days in space with four space walks totalling over 22 hours. Voss joined NASA's Johnson Space Center in 1984 as a vehicle integration test engineer. He was selected as an astronaut in 1987. He went on to be the deputy for flight operations in the Mission Integration and Operations Office for the Space Station Program.