Engineers are preparing to test parts of NASA's Space Launch System (SLS) rocket that will send humans to space. They installed an RS-25 engine on the A-1 Test Stand at Stennis Space Center. The Stennis team will perform developmental and flight certification testing of the RS-25 engine, a modified version of the space shuttle main engine. The SLS's core stage will be powered by a configuration of four RS-25 engines.
Early tests on the engine will collect data on the performance of its new advanced engine controller and other modifications. The controller regulates valves that direct the flow of propellant to the engine, which determines the amount of thrust generated during an engine test, known as a hotfire test. In flight, propellant flow and engine thrust determine the speed and trajectory of a spacecraft. The controller also regulates the engine startup sequence, which is especially important on an engine as sophisticated as the RS-25. Likewise, the controller determines the engine shutdown sequence, ensuring it will proceed properly under both normal and emergency conditions.
Testing of engine No. 0525 begins on a test stand originally built in the 1960s for Apollo-era engines that helped launch the lunar missions. The stand has since been used for several major testing projects, and NASA spent almost a year modifying the structure to accommodate the RS-25 engine.