NASA Conducts 5th Test in RS-25 Series Supporting Artemis Moon Missions July 14, 2021 NASA conducted a fifth RS-25 single-engine hot fire July 14 as a continuation of its ongoing seven-part test series, supporting development and production of engines for the agency’s Space Launch System (SLS) rocket on future missions to the Moon. Operators fired the engine for more than eight minutes (500 seconds) on the A-1 Test Stand at Stennis Space Center near Bay St. Louis, Mississippi, providing data to Aerojet Rocketdyne, lead contractor for the SLS engines, as it produces engines for use after the first four SLS flights. Four RS-25 engines, along with a pair of solid rocket boosters, will help power SLS, firing simultaneously to generate a combined 1.6 million pounds of thrust at launch and 2 million pounds during ascent.