KENNEDY SPACE CENTER, FLA. - Space Shuttle Program Manager Wayne Hale answers a question from a reporter during a press conference. He and NASA Launch Director Mike Leinbach and STS-114 External Tank Tiger Team lead Tim Wilson, with the NASA Engineering & Safety Center, briefed the media about the Space Shuttle Program and mission STS-121 from the press site at NASA's Kennedy Space Center in Florida. Photo credit: NASA/Jack Pfaller

KENNEDY SPACE CENTER, FLA. - NASA managers brief the media about the Space Shuttle Program and mission STS-121 from the press site at NASA's Kennedy Space Center in Florida. Public Information Officer Jessica Rye moderated. Seated at her right are Space Shuttle Program Manager Wayne Hale, NASA Launch Director Mike Leinbach and STS-114 External Tank Tiger Team lead Tim Wilson, with the NASA Engineering & Safety Center. Photo credit: NASA/Jack Pfaller

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is helped with his boot during suitup before heading to Launch Pad 39B and the third attempt at liftoff on mission STS-121. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is eager for a third launch attempt on the mission. Here, he is donning his launch suit before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Thomas Reiter is helped with his launch suit before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is eager for a third launch attempt on the mission. Here, he is donning his launch suit before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Michael Fossum is helped with his launch suit before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Piers Sellers fixes one of his gloves during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Pilot Mark Kelly fixes his glove during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Getting ready for a third launch attempt on mission STS-121, Mission Specialist Stephanie Wilson is suiting up before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Thomas Reiter is suiting up before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Stephanie Wilson gets help with her helmet during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Commander Steven Lindsey looks thoughtful as he completes suiting up before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - After suiting up in his launch suit, Mission Specialist Michael Fossum gives a thumbs up for a third launch attempt on mission STS-121. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Mission Specialist Thomas Reiter, happy to be making a third launch attempt on mission STS-121, is suited up before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is helped with her boots during suitup before heading to Launch Pad 39B and a third launch attempt. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Thomas Reiter is helped with his helmet during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Pilot Mark Kelly is helped with his boots during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is happy to be making a third launch attempt on the mission. She is suiting up before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is helped with her boot during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Pilot Mark Kelly is helped with his boot during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is helped with his helmet during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Michael Fossum adjusts part of his launch suit before heading to Launch Pad 39B. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Prior to the third launch attempt on mission STS-121, Mission Specialist Stephanie Wilson pulls on her gloves while getting help with her launch suit before heading to Launch Pad 39B. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Mission Specialist Piers Sellers adjusts his glove while donning his launch suit before heading to Launch Pad 39B and liftoff on mission STS-121. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is donning his launch and entry suit for launch today on Space Shuttle Discovery. Lindsey is making his fourth space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Looking relaxed, STS-121 Pilot Mark Kelly is donning his launch and entry suit for launch today on Space Shuttle Discovery. Kelly is making his second space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is helped with her launch suit during suitup for launch today on Space Shuttle Discovery. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - During suitup for launch today on Space Shuttle Discovery, STS-121 Mission Specialist Piers Sellers adjusts the communication device worn under his helmet. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Stephanie Wilson is helped with her helmet during suitup for launch today on Space Shuttle Discovery. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Pilot Mark Kelly arrives at the Shuttle Landing Facility to get ready for launch on July 1. The launch will be his second space flight. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. This mission is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Michael Fossum is helped with the communication device he wears under his helmet during suitup for launch today on Space Shuttle Discovery. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Michael Fossum is helped with his boot during suitup for launch today on Space Shuttle Discovery. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In the Vehicle Assembly Building at NASA’s Kennedy Space Center, workers are inspecting Solid Rocket Booster segments that will be used to launch Space Shuttle Atlantis on mission STS-121 in July. STS-121 is a Return to Flight Utilities and Logistics Flight (ULF-2) to the International Space Station.

KENNEDY SPACE CENTER, FLA. - In the Vehicle Assembly Building at NASA’s Kennedy Space Center, workers are inspecting Solid Rocket Booster segments that will be used to launch Space Shuttle Atlantis on mission STS-121 in July. STS-121 is a Return to Flight Utilities and Logistics Flight (ULF-2) to the International Space Station.

KENNEDY SPACE CENTER, FLA. - Launch Pad 39B at NASA Kennedy Space Center is clear after launch of Space Shuttle Discovery on Return to Flight mission STS-114. The Mobile Launcher Platform is still in place but will be moved to prepare for Space Shuttle Atlantis, the designated vehicle for mission STS-121 to the International Space Station. Launch of STS-121 is during a window extending from Sept. 9 to Sept. 25.

KENNEDY SPACE CENTER, FLA. - Launch Pad 39B at NASA Kennedy Space Center is clear after launch of Space Shuttle Discovery on Return to Flight mission STS-114. The Mobile Launcher Platform is still in place but will be moved to prepare for Space Shuttle Atlantis, the designated vehicle for mission STS-121 to the International Space Station. Launch of STS-121 is during a window extending from Sept. 9 to Sept. 25.

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Piers Sellers is eager for launch as he suits up before heading to Launch Pad 39B and liftoff. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak shows she is happy and excited to be preparing for launch with the fitting of her launch and entry suit. Nowak is making her first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In Firing Room 4 of the Launch Control Center, Shuttle Launch Director Mike Leinbach (center) and Center Director Jim Kennedy congratulate the launch team after the successful launch of Space Shuttle Discovery on mission STS-121. The launch was the first ever to take place on Independence Day. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In Firing Room 4 of the Launch Control Center, Shuttle Launch Director Mike Leinbach (center) congratulates the launch team after the successful launch of Space Shuttle Discovery on mission STS-121. The launch was the first ever to take place on Independence Day. At far right is Center Director Jim Kennedy. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - During Crew Equipment Interface Test (CEIT) at NASA’s Kennedy Space Center, STS-121 crew members inspect the docking station to become familiar with using the sockets. STS-121 is the second Return to Flight mission to the International Space Station. During CEIT, the crew has an opportunity to get a hands-on look at the orbiter and equipment they will be working with on their mission. Mission STS-121 is scheduled to launch aboard Space Shuttle Atlantis in July.

KENNEDY SPACE CENTER, FLA. - Waving flags for the Fourth of July, the STS-121 crew heads for the Astrovan and the ride to Launch Pad 39B for a third launch attempt. Leading the way are Pilot Mark Kelly (left) and Commander Steven Lindsey (right). Behind them are, left and right, Mission Specialists (second row) Lisa Nowak and Michael Fossum; (third row) Stephanie Wilson and Piers Sellers; and (at the rear) Thomas Reiter, who represents the European Space Agency. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Commander Steven Lindsey is helped by the Closeout Crew to prepare his launch suit for entering Discovery and the launch. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Regina Mitchell-Ryall & Tony Gray

KENNEDY SPACE CENTER, FLA. - Mission Specialist Piers Sellers is happy to be making a third launch attempt on mission STS-121. Here, he fixes one of his gloves during suitup before heading to Launch Pad 39B. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey arrives at KSC aboard a T-38 jet aircraft to get ready for launch on July 1. The launch will be the fourth for Lindsey. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. This mission is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Michael Fossum arrives at KSC aboard a T-38 jet aircraft to get ready for launch on July 1. The launch will be his first space flight. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. This mission is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In NASA Kennedy Space Center's Orbiter Processing Facility bay 3, United Space Alliance shuttle technicians remove the hard cover from a window on Space Shuttle Discovery to enable STS-121 crew members to inspect the window from the cockpit. Launch of Space Shuttle Discovery on mission STS-121, the second return-to-flight mission, is scheduled no earlier than May.

KENNEDY SPACE CENTER, FLA. - Space Shuttle Discovery lands on runway 15 at Kennedy Space Center's Shuttle Landing Facility at 9:14 a.m. EDT. Discovery's landing following the successful STS-121 mission was as exhilarating as its launch, the first to take place on America's Independence Day. During the nearly 13-day mission, the STS-121 crew tested new equipment and procedures to improve shuttle safety, and delivered supplies and made repairs to the International Space Station. Photo credit: NASA/Tom Farrar

KENNEDY SPACE CENTER, FLA. - The STS-121 crew displays the spirit of the Fourth of July holiday with their flags and their eagerness to launch as they stride out of the Operations and Checkout Building. Leading the way are Pilot Mark Kelly (left) and Commander Steven Lindsey (right). Behind them are Mission Specialists (second row) Lisa Nowak and Michael Fossum; (third row) Stephanie Wilson and Piers Sellers; and (at the rear) Thomas Reiter, who represents the European Space Agency. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Mission Specialist Stephanie Wilson is helped by the Closeout Crew to secure her launch suit before entering Discovery. Waiting in the back is Pilot Mark Kelly. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Regina Mitchell-Ryall & Tony Gray

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Mission Specialist Piers Sellers gets help from the Closeout Crew with final preparations on his launch suit before entering Discovery. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station.

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Mission Specialist Michael Fossum gets help from the Closeout Crew with final preparations on his launch suit before entering Discovery. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station.

KENNEDY SPACE CENTER, FLA. - In In the White Room on Launch Pad 39B, STS-121 Mission Specialist Lisa Nowak is helped by the Closeout Crew with final preparations on her launch suit before entering Discovery. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station.

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Mission Specialist Thomas Reiter is helped by the Closeout Crew to prepare for entering Discovery and the launch. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Regina Mitchell-Ryall & Tony Gray

KENNEDY SPACE CENTER, FLA. - Trying a third time for launch, and still smiling, the STS-121 crew gathers again for the traditional breakfast before suiting up. Seated left to right are Mission Specialists Piers Sellers and Michael Fossum, Pilot Mark Kelly, Commander Steven Lindsey, and Mission Specialists Lisa Nowak, Stephanie Wilson and Thomas Reiter, who represents the European Space Agency. The July 2 launch attempt was scrubbed due to the presence of showers and thunderstorms within the surrounding area of the launch site. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In the White Room on Launch Pad 39B, STS-121 Pilot Mark Kelly heads for the Closeout Crew who will help with final preparations on his launch suit before entering Discovery. Situated on the end of the orbiter access arm, the White Room provides access into the orbiter on the pad. The crew is preparing for the third launch attempt in four days; previous attempts were scrubbed due to weather concerns. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station.

KENNEDY SPACE CENTER, FLA. - Smoke and steam billow across Launch Pad 39B as the launch of Space Shuttle Discovery on mission STS-121 kicks off the fireworks for the U.S. holiday and makes history as the first time a shuttle has launched on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Tony Gray & Tim Powers

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Having his boot worked on is Mission Specialist Thomas Reiter, who represents the European Space Agency. Reiter is making his first space shuttle flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In Firing Room 4 of the Launch Control Center, the launch team stands to view the liftoff of Space Shuttle Discovery on mission STS-121 -- the first ever Independence Day launch of a space shuttle. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Here, Mission Specialist Thomas Reiter, who represents the European Space Agency, is ready to go. Reiter is making his first space shuttle flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Members of the launch team in Firing Room 4 of the Launch Control Center watch the historic ride of Space Shuttle Discovery as it rockets through the sky on mission STS-121 -- the first ever Independence Day launch of a space shuttle. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Smoke and steam billow across Launch Complex 39B as the launch of Space Shuttle Discovery on mission STS-121 kicks off the fireworks for the U.S. holiday and making history as the first time a shuttle has launched on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Sandy Joseph & Robert Murray

KENNEDY SPACE CENTER, FLA. - For the second time in two days, STS-121 Mission Specialist Stephanie Wilson is donning her launch suit for another launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In Firing Room 4 of the Launch Control Center, NASA launch team members cheer and wave American flags at the successful launch of Space Shuttle Discovery on mission STS-121. The launch made history as the first to occur on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Bill Ingalls

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is still eager for launch after suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak is still eager for launch during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Lisa Nowak gets help with her launch suit for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - For the second morning in a row, the STS-121 crew sit for their traditional breakfast before suiting up for launch. Seated from left are Mission Specialists Piers Sellers and Michael Fossum, Pilot Mark Kelly, Commander Steven Lindsey, and Mission Specialists Lisa Nowak, Stephanie Wilson and Thomas Reiter, who represents the European Space Agency. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch of Space Shuttle Discovery on mission STS-121 is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - On Launch Pad 39B, Space Shuttle Discovery is bathed in spotlights under dark skies after the scrub of the launch attempt on mission STS-121. The White Room extends toward the cockpit area where the STS-121 crew patiently waited for the launch just hours earlier. The launch was scrubbed due to weather concerns and postponed 24 hours. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, FLA. - On Launch Pad 39B, Space Shuttle Discovery is bathed in spotlights under dark skies after the scrub of the launch attempt on mission STS-121. The White Room is still extended toward the cockpit area where the STS-121 crew patiently waited for the launch just hours earlier. The launch was scrubbed due to weather concerns and postponed 24 hours. Photo credit: NASA/Ken Thornsley

KENNEDY SPACE CENTER, FLA. - As smoke and team billow across Launch Pad 39B, Space Shuttle Discovery on mission STS-121 kicks off the fireworks for the U.S. holiday and makes history as the first time a shuttle has launched on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Tony Gray

KENNEDY SPACE CENTER, FLA. - Workers in Firing Room 4 of the Launch Control Center take advantage of the view as Space Shuttle Discovery lifts off on mission STS-121 -- the first ever Independence Day launch of a space shuttle. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - After their arrival at the Shuttle Landing Facility to get ready for launch July 1, STS-121 Mission Specialist Thomas Reiter (second from left) and Commander Steven Lindsey are greeted (at right) by Center Director Jim Kennedy and Shuttle Launch Director Mike Leinbach. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. This mission is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Standing here is Mission Specialist Stephanie Wilson, who is making her first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Pilot Mark Kelly adjusts his helmet during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Adjusting his helmet is Mission Specialist Michael Fossum, who is making his first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Piers Sellers finishes suiting up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Having her boot worked on is Mission Specialist Lisa Nowak, who is making her first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Thomas Reiter is suiting up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. Reiter represents the European Space Agency. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Cameras are the accessory of the day at the Kennedy Space Center's Banana River viewing site. All eyes and lenses are focused on Launch Pad 39B and the successful launch of Space Shuttle Discovery on mission STS-121. It was the third launch attempt in four days; the others were scrubbed due to weather concerns. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Louie Roguevert

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Here, Mission Specialist Piers Sellers adjusts his glove. Sellers is making his second space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Here, Mission Specialist Piers Sellers adjusts part of his helmet. Sellers is making his second space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Michael Fossum has suited up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Pilot Mark Kelly gets help with his helmet fitting during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - For the second time in two days, STS-121 Mission Specialist Stephanie Wilson is suiting up for a launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The moment of ignition is captured in this photo of Space Shuttle Discovery being launched on mission STS-121 from Launch Pad 39B. The launch was the first ever made on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 17 at Kennedy's Shuttle Landing Facility. Photo courtesy of Nikon/Scott Andrews

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Mission Specialist Stephanie Wilson is excited about making her first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey is suiting up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey adjusts a glove during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Thomas Reiter is suiting up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. Reiter represents the European Space Agency. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - The STS-121 crew are donning their orange launch and entry suits for launch today on Space Shuttle Discovery. Seated here is Mission Specialist Michael Fossum, who is making his first space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - From Firing Room 4 of the Launch Control Center, NASA Administrator Mike Griffin uses binoculars to view of the launch of Space Shuttle Discovery (in the background) on mission STS-121. The launch made history as the first to occur on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Bill Ingalls

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey adjusts his glove as he dons his launch and entry suit for launch today on Space Shuttle Discovery. Lindsey is making his fourth space flight. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - STS-121 Commander Steven Lindsey pulls on his glove during suitup for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - Under clear blue skies, the launch of Space Shuttle Discovery on mission STS-121 kicks off the fireworks for the U.S. holiday in its third launch attempt in four days. Liftoff from Launch Pad 39B was on-time at 2:38 p.m. EDT. During the 12-day mission, the STS-121 crew of seven will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Landing is scheduled for July 16 or 17 at Kennedy's Shuttle Landing Facility. Photo credit: NASA/Sandy Joseph & Robert Murrary

KENNEDY SPACE CENTER, FLA. - STS-121 Mission Specialist Piers Sellers is suiting up for a second launch attempt on Space Shuttle Discovery. The first launch attempt July 1 was scrubbed due to weather concerns and postponed 24 hours. The launch is the 115th shuttle flight and the 18th U.S. flight to the International Space Station. During the 12-day mission, the STS-121 crew will test new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo credit: NASA/Kim Shiflett

KENNEDY SPACE CENTER, FLA. - In NASA Kennedy Space Center's Orbiter Processing Facility bay 3, STS-121 Pilot Mark Kelly and Mission Specialist Stephanie Wilson are joined by two shuttle technicians as they examine the orbiter boom sensor system in Discovery's payload bay. 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.

Astronauts Steve Lindsey (left), Stephanie Wilson, Lisa Nowak and Piers Sellers meet with employees at NASA Stennis Space Center. The crewmembers on NASA's space shuttle mission STS-121, which launched July 4, 2006, thanked SSC's workers for their dedication and safe work history. `We feel blessed that you are a part of the NASA family,' Wilson said. All four expressed gratitude for the reliability of the space shuttle's main engines, which helped propel the STS-121 crew into orbit on their 13-day mission.

KENNEDY SPACE CENTER, FLA. - In NASA Kennedy Space Center's Orbiter Processing Facility bay 3, STS-121 Commander Steve Lindsey inspects one of the windows that will fly on Space Shuttle Discovery during the mission. 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.