The Space Launch System rocket’s interim cryogenic propulsion stage (ICPS) and boosters were powered up overnight. Teams are in the process of clearing all non-essential personnel from the launch pad area in preparation for propellant loading operations.
At 6 a.m. EDT, or L-8 hours, 40 minutes, the launch team is expected to reach a planned 1 hour, 30-minute built-in hold. During this time the mission management team will review the status of operations, receive a weather briefing, and make a “go” or “no-go” decision to proceed with tanking operations.
Tanking milestones include filling the rocket’s core stage with several hundred thousand gallons of liquid oxygen and liquid hydrogen. This will occur over a series of different propellant loading milestones to fill, top off, and replenish the tank. Because of an issue found several days ago with a helium check valve on the rocket which cannot be fixed at the launch pad, cryogenic propellant will not be loaded into the rocket’s upper stage.