RS-25 rocket engine No. 2059 is removed from the A-1 Test Stand at Stennis Space Center on May 19, 2016. The engine was tested March 10 on the stand and is ready for use on NASA’s new Space Launch System (SLS) vehicle. NASA is developing the SLS to carry humans deeper into space than ever before. The SLS core stage will be powered by four RS-25 engines. Engine No. 2059 is scheduled for use on the first crewed SLS mission, Exploration Mission-2, which will carry American astronauts beyond low-Earth orbit for the first time since 1972. The photo above shows the engine, as well as the yellow thrust frame adapter above it, which holds the engine in place for testing.