KENNEDY SPACE CENTER, FLA. - During a Crew Equipment Interface Test (CEIT) inside the Space Station Processing Facility at NASA's Kennedy Space Center, STS-121 Mission Specialists Michael Fossum (left) and Piers Sellers practice removing the cover from the trailing umbilical system reel assembly that will be installed on the International Space Station during their mission. A CEIT provides hands-on experiences with equipment used on-orbit. Mission STS-121 is the second in the Return to Flight sequence and will carry on improvements that debuted during last year's STS-114 mission and build upon those tests. Launch is scheduled in July. Photo credit: NASA/Kim Shiflett KSC-06pd0541