Workers take as Space Shuttle Discovery lifts off on mission STS-121 the first Independence Day launch of a space shuttle.

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