The mission management team has polled “go” to proceed with the terminal count sequence. The launch director is also “go” and teams have set a new target launch time of 1:47 a.m. EST and the countdown clock  resumed at 1:37 a.m.

With approval from the launch director and managers, a series of countdown milestones for the Artemis I terminal count to launch will be initiated by the Ground Launch Sequencer at T-10 minutes:

  • Ground Launch Sequencer (GLS) initiates terminal count (T-10M)
  • GLS go for core stage tank pressurization (T-6M)
  • Orion ascent pyros are armed (T-6M)
  • Orion set to internal power (T-6M)
  • Core Stage LH2 terminate replenish (T-5M57S)
  • GLS is go for flight termination system (FTS) arm (T-5M)
  • GLS is go for LH2 high flow bleed check (T-4M40S)
  • GLS is go for core stage auxiliary power unit (APU) start (T-4M)
  • Core Stage auxiliary power unit starts (T-4M)
  • Core stage L0X terminate replenish (T-4M)
  • ICPS LOX terminate replenish (T-3M30S)
  • GLS is go for purge sequence 4 (T-3M10S)
  • ICPS switches to internal battery power (T-1M56S)
  • Core stage switches to internal power (T-1M30S)
  • ICPS enters terminal countdown mode (T-1M20S)
  • ICPS LH2 terminate replenish (T-50S)
  • GLS sends “Go for automated launch sequencer” command (T-33S)
  • Core stage flight computer to automated launching sequencer (T-30S)
  • Hydrogen burn off igniters initiated (T-12S)
  • GLS sends the command for core stage engine start (T-10S)
  • RS-25 engines startup (T-6.36S)

Liftoff (T-0)

  • Solid rocket booster separation (Mission Elapsed Time 00:02:12)
  • Service module fairing jettison (MET 00:03:11)
  • Launch abort system jettison (MET 00:03:16)
  • Core stage main engine cutoff commanded (MET 00:08:03)
  • Core stage/ICPS separation (MET 00:08:15)
  • Orion solar array wing deploy begins (MET 00:18:09) – approx. 12 min duration
  • Perigee raise maneuver (MET 00:52:56)
  • Trans-lunar injection (MET 01:29:27)
  • Orion/ICPS separation (MET 01:57:36)

The timing of events after liftoff may vary by a few seconds.

Launch Managers Give “Go” to Proceed with Terminal Count, Launch Set for 1:47 a.m.