In NASA Kennedy Space Center's Orbiter Processing Facility bay 3, members of the STS-121 crew, under the watchful eyes of Tomas Gonzalez-Torres, with NASA's Johnson Space Center, practice working with hardware for the mission. Seen are (second from left) Mission Specialists Michael Fossum and Piers Sellers and Pilot Mark Kelly. The crew is at Kennedy to take part in the crew equipment interface test, which provides hands-on experience with equipment to be used on-orbit. Launch of Space Shuttle Discovery on mission STS-121, the second return-to-flight mission, is scheduled no earlier than May.