Stock Photo - FILE: In this photo released by NASA, waving flags for the Fourth of July, the STS-121 crew heads for the Astrovan and the ride to Launch Pad 39B at the Kennedy Space Center, Florida on July 4, 2006 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 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. .Mandatory Credit: Kim Shiflett - NASA via CNP | usage worldwide. - Kennedy Space Center/Florida/United States of America