KENNEDY SPACE CENTER, FLA. -- Space shuttle Atlantis STS-122 Mission Specialist Leland Melvin, strapped in his seat on Atlantis' fight deck, signals that he is ready to proceed with the simulated launch countdown. The exercise is part of terminal countdown demonstration test, or TCDT, activities at NASA's Kennedy Space Center. The TCDT is a dress rehearsal for launch and also provides astronauts and ground crews with equipment familiarization and emergency egress training. On mission STS-122, Atlantis will deliver the Columbus module to the International Space Station. The European Space Agency's largest single contribution to the station, Columbus is a multifunctional, pressurized laboratory that will be permanently attached to U.S. Node 2, called Harmony. The laboratory will expand the research facilities aboard the station, providing crew members and scientists from around the world the ability to conduct a variety of experiments in the physical, materials and life sciences. At