CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Pilot Tony Antonelli is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Antonelli and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Joseph Acaba is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Acaba and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Steve Swanson is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Swanson and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Richard Arnold is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Behind Arnold is Pilot Tony Antonelli. Arnold, Antonelli and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Commander Lee Archambault is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Archambault and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist John Phillips has donned the harness over his launch-and-entry suit. The White Room provides access into space shuttle Discovery. Phillips and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Koichi Wakata is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Wakata and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist John Phillips (center) is helped by the Closeout Crew to put on his harness. Phillips will join Commander Lee Archambault (background right) and other crew members to enter space shuttle Discovery to conduct a simulated launch countdown. The astronauts are at Kennedy to prepare for launch through Terminal Countdown Demonstration Test activities. The TCDT includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Sandra Joseph, Kevin O'Connell, Tom Farrar

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Pilot Tony Antonelli is helped by the Closeout Crew to put on his harness. Antonelli will enter space shuttle Discovery along with the other crew members to conduct a simulated launch countdown. The astronauts are at Kennedy to prepare for launch through Terminal Countdown Demonstration Test activities. The TCDT includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Sandra Joseph, Kevin O'Connell, Tom Farrar

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Richard Arnold (foreground) is helped by the Closeout Crew to put on his harness. Arnold will join Pilot Tony Antonelli (background right) and other crew members to enter space shuttle Discovery to conduct a simulated launch countdown. The astronauts are at Kennedy to prepare for launch through Terminal Countdown Demonstration Test activities. The TCDT includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Sandra Joseph, Kevin O'Connell, Tom Farrar

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Koichi Wakata is helped by the Closeout Crew to put on his harness. Wakata will join other crew members to enter space shuttle Discovery to conduct a simulated launch countdown. The astronauts are at Kennedy to prepare for launch through Terminal Countdown Demonstration Test activities. The TCDT includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Sandra Joseph, Kevin O'Connell, Tom Farrar

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Commander Lee Archambault is helped by the Closeout Crew to put on his harness. Archambault will enter space shuttle Discovery along with the other crew members to conduct a simulated launch countdown. The astronauts are at Kennedy to prepare for launch through Terminal Countdown Demonstration Test activities. The TCDT includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Sandra Joseph, Kevin O'Connell, Tom Farrar

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Steve Swanson is ready to enter space shuttle Discovery, behind him. The White Room provides access into Discovery. Swanson and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Joseph Acaba is ready to enter space shuttle Discovery, behind him. The White Room provides access into Discovery. Acaba and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Richard Arnold gets ready to enter space shuttle Discovery, behind him. The White Room provides access into Discovery. Arnold and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann

CAPE CANAVERAL, Fla. – In the White Room on NASA Kennedy Space Center's Launch Pad 39A, STS-128 Commander Rick Sturckow is helped with his harness before entering space shuttle Discovery. The White Room is at the end of the orbiter access arm and provides entry into the shuttle. The crew is at Kennedy to take part in the terminal countdown demonstration test, or TCDT, which includes equipment familiarization, emergency exit training and a simulated countdown. On the STS-128 mission, Discovery will deliver 33,000 pounds of equipment to the station, including science and storage racks, a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill. Launch is targeted for late August. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – In the White Room on NASA Kennedy Space Center's Launch Pad 39A, STS-128 Mission Specialist Nicole Stott is helped getting into her parachute harness before entering space shuttle Discovery. The White Room is at the end of the orbiter access arm and provides entry into the shuttle. The crew is at Kennedy to take part in the terminal countdown demonstration test, or TCDT, which includes equipment familiarization, emergency exit training and a simulated countdown. On the STS-128 mission, Discovery will deliver 33,000 pounds of equipment to the station, including science and storage racks, a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill. Launch is targeted for late August. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. – In the White Room on the orbiter access arm of the fixed service structure on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-127 Pilot Doug Hurley is helped to secure the harness over his launch-and-entry suit. He will enter space shuttle Endeavour for the simulated launch countdown. The crew is at Kennedy for a launch dress rehearsal called the terminal countdown demonstration test, or TCDT, which includes the simulation, emergency exit training and equipment familiarization. Endeavour's STS-127 mission is the final of three flights dedicated to the assembly of the Japanese Kibo laboratory complex on the International Space Station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Troy Cryder