NASA engineers capped a year of Space Launch System testing with a final RS-25 rocket engine hot fire on Dec. 13 at Stennis Space Center near Bay St. Louis, Miss. The 470-second test on the A-1 Test Stand was a “green run” test of an RS-25 flight controller. It marked the eighth RS-25 test of the year and the sixth flight controller to be tested for use on NASA’s new Space Launch System (SLS) vehicle. The engine tested also included a large 3-D-printed part scheduled for use on future RS-25 flight engines.