KENNEDY SPACE CENTER, Fla. -- STS-118 Commander Scott Kelly climbs aboard the shuttle training aircraft, known as an STA, for landing practice. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown.The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- One of two shuttle training aircraft, or STA, taxis out to the runway at the Shuttle Landing Facility. STS-118 Commander Scott Kelly and Pilot Charlie Hobaugh are each piloting one of the STAs for landing practice. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- STS-118 Commander Scott Kelly checks the fit of his launch and entry suit. The fitting is part of the Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. Kelly is suiting up also for landing practice in the shuttle training aircraft, known as an STA. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- STS-118 Commander Scott Kelly settles in his cockpit seat aboard the shuttle training aircraft, known as an STA, for landing practice. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- Two shuttle training aircraft, or STAs, wait to taxi onto the runway at the Shuttle Landing Facility. STS-118 Commander Scott Kelly and Pilot Charlie Hobaugh are each piloting one of the STAs for landing practice. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- STS-118 Commander Scott Kelly, left, and Pilot Charlie Hobaugh check the fit of their launch and entry suits. The fitting is part of the Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. Kelly and Hobaugh are suiting up also for landing practice in the shuttle training aircraft, known as an STA. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- Dressed in their launch and entry suits, STS-118 Pilot Charlie Hobaugh and Commander Scott Kelly (waving) are headed for the runway for landing practice in the shuttle training aircraft, known as an STA. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew gets instructions on emergency exit procedures from Launch Pad 39A. From left are Mission Specialist Rick Mastracchio, Pilot Charlie Hobaugh, Mission Specialist Alvin Drew, Commander Scott Kelly, and Mission Specialists Tracy Caldwell, Dave Williams and Barbara R. Morgan, whojoined NASA's Teacher in Space program in 1985. She was selected as an astronaut in 1998. TCDT activities include the M-113 training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. From left are Mission Specialists Barbara R. Morgan, Dave Williams and Rick Mastracchio. Williams represents the Canadian Space Agency. Morgan joined NASA's Teacher in Space program in 1985 and was selected as an astronaut in 1998. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. From left are Mission Specialist Barbara R. Morgan, Commander Scott Kelly and Mission Specialist Alvin Drew. Morgan joined NASA's Teacher in Space program in 1985 and was selected as an astronaut in 1998. DT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. From left are Mission Specialist Barbara R. Morgan, Commander Scott Kelly and Mission Specialist Alvin Drew. Morgan joined NASA's Teacher in Space program in 1985 and was selected as an astronaut in 1998. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. From left are Mission Specialists Alvin Drew; Barbara R. Morgan; Dave Williams, representing the Canadian Space Agency; Rick Mastracchio; Tracy Caldwell; Pilot Charlie Hobaugh and Commander Scott Kelly. Morgan joined NASA's Teacher in Space program in 1985 and was selected as an astronaut in 1998. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. Shuttle Launch Director Mike Leinbach (left) welcomes Mission Specialists Tracy Caldwell, Rick Mastracchio and Dave Williams of the Canadian Space Agency, as Commander Scott Kelly (back to camera) looks on. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. Commander Scott Kelly (at microphone) introduces his crew to media representatives on site to welcome them. From left are Mission Specialists Alvin Drew; Barbara R. Morgan; Dave Williams, representing the Canadian Space Agency; Rick Mastracchio; Tracy Caldwell; and Pilot Charlie Hobaugh. Morgan joined NASA's Teacher in Space program in 1985 and was selected as an astronaut in 1998. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/George Shelton

KENNEDY SPACE CENTER, Fla. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. Mission Specialist Barbara R. Morgan, NASA's first educator astronaut, acknowledges those who have turned out to welcome them. TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, FLA. -- The STS-118 crew arrives at Kennedy's Shuttle Landing Facility aboard a Shuttle Training Aircraft to take part in the Terminal Countdown Demonstration Test (TCDT), a dress rehearsal for launch. Shuttle Launch Director Mike Leinbach (left) welcomes Commander Scott Kelly (right). TCDT activities include M-113 armored personnel carrier training, payload familiarization, emergency egress training at the pad and a simulated launch countdown. The STS-118 payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. The mission is the 22nd flight to the International Space Station and is targeted for launch on Aug.7. Photo credit: NASA/George Shelton