Astronauts Steve Lindsey (left), Stephanie Wilson, Lisa Nowak and Piers Sellers meet with employees at NASA Stennis Space Center. The crewmembers on NASA's space shuttle mission STS-121, which launched July 4, 2006, thanked SSC's workers for their dedication and safe work history. `We feel blessed that you are a part of the NASA family,' Wilson said. All four expressed gratitude for the reliability of the space shuttle's main engines, which helped propel the STS-121 crew into orbit on their 13-day mission.