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. - 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 (foreground) cheers over the successful liftoff of Space Shuttle Discovery, watching it rocket through the sky on mission STS-121 -- the first ever Independence Day launch of a space shuttle. At far left is Stephanie Stilson, NASA flow director in the Process Integration Branch of the Shuttle Processing Directorate, who began conducting Discovery's processing operations in December 2000. 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. - In Firing Room 4 of the Launch Control Center, NASA Administrator Mike Griffin congratulates the launch team on the successful launch of Space Shuttle Discovery on mission STS-121. The launch was the first ever to take place on Independence Day. Liftoff was on-time at 2:38 p.m. EDT. Others next to Griffin are (left to right) David R. Mould, assistant administrator for NASA Public Affairs ; Lisa Malone, director of External Relations at Kennedy; Bruce Buckingham, news chief at the NASA News Center at Kennedy; and Mike Leinbach, Shuttle Program director. 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, Kennedy Space Center Director Jim Kennedy watches one of the computer screens as the countdown heads for launch of Space Shuttle Discovery on mission STS-121. 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. - In Firing Room 4 of the Launch Control Center, Shuttle Launch Director Mike Leinbach (center) is congratulated by NASA Administrator Mike Griffin (right) for the successful launch of Space Shuttle Discovery on mission STS-121. The launch was the first ever to take place on Independence Day. Behind Leinbach are David R. Mould, assistant administrator for Public Affairs NASA, and Lisa Malone, director of External Relations at Kennedy. 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. - 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. - 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. - In Firing Room 4 of the Launch Control Center, Shuttle Program manager Wayne Hale (far left), NASA Associate Administrator for Space Operations Mission Bill Gerstenmaier (third from left) and Center Director Jim Kennedy (far right) 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. - 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