STENNIS SPACE CENTER, Miss. -- The RS-25 engine, the propulsion system that was highly successful as the Space Shuttle Main Engine, is preparing for a new life with the Space Launch System. Testing at SSC will initially focus on a new Main Engine Controller (MEC) and the ability to accommodate the full range of propellant conditions in its new configuration with the SLS launch vehicle.. SSC engineers have been installing a 7,755-pound thrust frame adapter for the A-1 test stand in order to testing the RS-25s. The first engine on the stand will be 0525. The engine never flew in space, as it was one of two development engines used for component testing on Stand A-2 to support shuttle flights. The other was 0528. (Source: Spaceflight, 02/11/14) Background article