KENNEDY SPACE CENTER, FLA. - The STS-121 crew have breakfast in the Operations and Checkout Building at NASA's Kennedy Space Center before suiting up for the simulated countdown at the launch pad. Seated left to right are Mission Specialists Thomas Reiter of Germany and Michael Fossum, Pilot Mark Kelly, Commander Steven Lindsey, and Mission Specialists Lisa Nowak, Piers Sellers and Stephanie Wilson. Reiter represents the European Space Agency. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Pilot Mark Kelly is helped with his glove after donning his launch and entry suit in preparation for the simulated countdown he and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey has his helmet secured to his launch and entry suit in preparation for the simulated countdown he and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is helped with her boot after donning her launch and entry suit in preparation for the simulated countdown she and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Piers Sellers signals okay after donning his launch and entry suit in preparation for the simulated countdown he and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The suited STS-121 crew members stride out of the Operations and Checkout Building on their way to Launch Pad 39B for a simulated countdown. Leading the way are Pilot Mark Kelly (left) and Commander Steven Lindsey. Behind Kelly are Mission Specialists Lisa Nowak, Stephanie Wilson and Thomas Reiter of Germany, who represents the European Space Agency. Behind Lindsey are Mission Specialists Michael Fossum and Piers Sellers. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - At the Shuttle Landing Facility, STS-121 Pilot Mark Kelly gets ready for a training flight in a Shuttle Training Aircraft (STA). He will be practicing landing the orbiter using the STA, which is a modified 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. Because the orbiter is unpowered during re-entry and landing, its high-speed glide must be perfectly executed the first time. Space Shuttle Discovery is scheduled to launch July 1 on mission STS-121. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Michael Fossum has donned his launch and entry suit in preparation for the simulated countdown he and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Stephanie Wilson signals all is well after donning her launch and entry suit in preparation for the simulated countdown she and other crew members will undertake. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Thomas Reiter wears his launch and entry suit in preparation for the simulated countdown he and other crew members will undertake. Reiter is from Germany and represents the European Space Agency. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The suited STS-121 crew members walk to the bus that will take them to Launch Pad 39B for a simulated countdown. On the left, back to front, are Mission Specialists Stephanie Wilson and Lisa Nowak, and Pilot Mark Kelly. On the right, back to front, are Mission Specialists Thomas Reiter of Germany, Piers Sellers and Michael Fossum, and Commander Steven Lindsey. Reiter represents the European Space Agency. The crew is taking part in Terminal Countdown Demonstration Test activities, including the dress rehearsal for launch. Mission STS-121 is scheduled to be launched July 1. Photo credit: NASA/Kim Shiflett