Louis Stork, 13, and Erin Whittle, 14, look on as Brianna Johnson, 14, conducts a 'test' of a space shuttle main engine in the Test Control Center exhibit in StenniSphere, the visitor center at NASA's John C. Stennis Space Center near Bay St. Louis, Miss. The young people were part of a group from Mobile Christian School in Mobile, Ala., that visited StenniSphere on April 21.