After a hot fire test in January ended early, NASA decided it needed more data on the rocket core stage that it plans to use for missions to the Moon. So today at Stennis Space Center, all four RS-25 engines fired for 499.6 seconds, simulating what they will undergo during every trip to the Moon for the Artemis space program by throttling up and down, and moving to direct thrust.
In a statement, acting NASA Administrator Steve Jurczyk said "Today’s successful hot fire test of the core stage for the SLS is an important milestone in NASA’s goal to return humans to the lunar surface – and beyond." Next, the core stage will go to Kennedy Space Center in Florida where assembly will start preparing to make it part of Artemis I. And that can't come soon enough, as the Space Launch System project is already years behind the original launch projection of 2019.