The space agency plans to test-fire the four main engines of its first SLS heavy-lift booster on Saturday (Jan. 16) at the Stennis Space Center in Mississippi. It's a critical test for NASA and the final step in the agency's "Green Run" series of tests to ensure the SLS rocket is ready for its first launch, Artemis 1, that will send an uncrewed Orion spacecraft around the moon later this year.

The SLS is NASA's go-to rocket to send astronauts to the moon by 2024 as part of its Artemis program. Artemis 1 is the first of what's expected to be a series of missions leading up to Artemis 3, NASA's first crewed moon landing since the Apollo era.

In the upcoming hot-fire engine test, engineers will load the Boeing-built SLS core booster with over 700,000 gallons of cryogenic (that's really cold) propellant into the rocket's fuel tanks and light all four of its RS-25 engines at once. The engines will fire for 485 seconds (a little over 8 minutes) and generate a whopping 1.6 million pounds of thrust throughout the test.