The largest rocket element NASA has ever built, the core stage of NASA’s Space Launch System (SLS) rocket, fired its four RS-25 engines for 8 minutes and 19 seconds Thursday at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. The successful test, known as a hot fire, is a critical milestone ahead of the agency’s Artemis I mission, which will send an uncrewed Orion spacecraft on a test flight around the Moon and back to Earth, paving the way for future Artemis missions with astronauts.