The new series of tests are using a developmental engine that is attached to Stennis' A-1 Test Stand, and not one of the actual engines that will be part of an SLS launch. The four engines that will power Exploration Mission-1 have already made their way over to NASA's Michoud Assembly Facility in New Orleans where they will be connected to a core stage. The core stage with all four engines will return for testing at Stennis for a full engine burn on its B-2 Test Stand.