Fast fill is underway for the Space Launch System (SLS) rocket’s core stage liquid oxygen (LOX) tank. Next, teams will transition from slow fill to fast fill for the liquid hydrogen (LH2) tank and initiate, or “kick start,” the engine bleed, which will begin flowing supercold LH2 to start cooling the four RS-25 engines down to the temperature conditions required for launch.

Follow along with live coverage and with the countdown milestones for the cryogenic demonstration test ahead of the Artemis I mission.

Artemis Cryogenic Test: Core Stage LOX Fast Fill Underway, Proceeding Toward LH2 Slow Fill