STS-121 Pilot Mark Kelly is donning his launch and entry suit before the walkout and ride to Launch Pad 39B.

Smiling at the prospect of launch, STS-121 Pilot Mark Kelly is donning his launch and entry suit before the walkout and ride to Launch Pad 39B. 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