Space Shuttle Discovery kicks off the Fourth of July fireworks with its own fiery display as it rockets into the blue sky, spewing foam and smoke over the ground, 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 17 at Kennedy’s Shuttle Landing Facility.