STS121-S-064 (17 July 2006) --- Dr. Michael Griffin (right), NASA administrator; and William H. Gerstenmaier, associate administrator for Space Operations, inspect the Space Shuttle Discovery after the landing and conclusion of mission STS-121. The crew of seven tested new equipment and procedures to improve shuttle safety, as well as deliver supplies and make repairs to the International Space Station. Photo Credit: NASA/Bill Ingalls