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 on March 18 at NASA’s Stennis Space Center. 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.

Engineers designed the eight-part Green Run test campaign to gradually bring the SLS core stage to life for the first time, culminating with the hot fire. The team will use data from the tests to validate the core stage design for flight.

NASA previously conducted a hot fire test of the SLS core stage on January 16, 2020. The four RS-25 engines fired together for the first time for about one minute before the test ended earlier than planned. Following data analysis, NASA determined a second, longer hot fire test would provide valuable data to help verify the core stage design for flight, while posing minimal risk to the Artemis I core stage.

During the second hot fire test, the stage fired the engines for a little more than eight minutes, just like it will during every Artemis launch to the Moon. The longer duration hot fire tested a variety of operational conditions, including moving the four engines in specific patterns to direct thrust and powering the engines up to 109% power, throttling down and back up, as they will during flight.

Test teams at Stennis supervised a network of 114 tanker trucks and six propellant barges that provided liquid propellant through the B-2 Test Stand to the core stage. Test teams also delivered operational electrical power, supplied more than 1,135,623 liters (330,000 gallons) of water per minute to the stand’s flame deflector, and monitored structural interfaces of both the hardware and the stand.

SLS, Orion, and the ground systems at Kennedy, along with the human landing system and the Gateway in orbit around the Moon, are NASA’s backbone for deep space exploration. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon on a single mission. The exploration of the Moon with NASA’s Artemis program includes preparations to send astronauts to Mars as part of America’s Moon to Mars exploration approach.

For more on NASA’s SLS, visit https://www.nasa.gov/sls.

For more on NASA’s SLS core stage Green Run test series, visit https://www.nasa.gov/greenrun.