NASA and Boeing are ready to light up the core stage of the massive Space Launch System (SLS) rocket in a second hot fire test, currently scheduled for Thursday (Feb. 25).

The critical engine test is the last installment of an eight-part, year-long green run test meant to ensure that the massive rocket will work properly on its first launch, which will send the uncrewed Artemis 1 mission around the moon. A first attempt at the hot fire test, which occurred on Jan. 16, ended early when the engines shut off after firing for about 67 seconds. The test had been targeting an eight-minute fire to simulate the work the rocket will do during launch.