A team of NASA specialists conducted another test of the RS-25 rocket engine with serial number 10001 at the Stennis Space Center, located near Bay St. Louis, Mississippi. The test took place on October 21, 2026 and consisted of a hot-fire test lasting nearly eight and a half minutes, or 500 seconds. This engine operating duration is not arbitrary — it is the exact amount of time the RS-25 functions during an actual launch of NASA's heavy-lift Space Launch System (SLS) rocket, which is used as part of the Artemis lunar program. During the test, the engine operated at 111% of its nominal power level, which allows engineers to verify its performance under conditions approaching maximum operational loads. Such tests are an integral part of the program preparing RS-25 engines for future missions. They enable NASA specialists and contractors to gather data on the operation of turbopumps, combustion chambers, and other critical engine components, confirming their reliability and flight readiness. Stennis Space Center has traditionally served as the primary test facility for such hot-fire tests of rocket engines used in the American space program. The RS-25 engines, formerly known as the Space Shuttle Main Engines (SSME), have been adapted for use as part of the SLS rocket. Each SLS rocket is equipped with four such engines, which provide the primary thrust during the ascent phase to place the Orion spacecraft and other payload on a trajectory toward the Moon.