NASA prepares for major test firing of largest rocket since Saturn V By (0) NASA's Space Launch System moon rocket, shown during recent fuel-loading tests at Stennis Space Center in Mississippi, is prepared for an eight-minute test firing Saturday. Photo courtesy of NASA NASA plans a test firing of the agency's huge SLS moon rocket, shown in an artist's conception here, on Saturday in Mississippi. Image courtesy of NASA NASA's Space Launch System moon rocket, shown during recent fuel-loading tests at Stennis Space Center in Mississippi, is prepared for an eight-minute test firing Saturday. Photo courtesy of NASA Jan. 15 (UPI) -- NASA plans to ignite one of the largest and most powerful rockets ever built, the Space Launch System core stage, for an eight-minute test firing Saturday.