Making Synapses · Bringing Knowledge to Mankind
SpaceGo for the automated launch sequencer
At T-33 seconds the ground hands the count to the rocket. The ground launch sequencer sends "go for automated launch sequencer", the core stage flight computer takes over and, from that moment, there is no recycle left for the day. You run the last half minute of the Artemis II count, up to the start of the RS-25 engines.
Free to startScenarios
- Everything nominal: the handover happens at T-33 seconds and the engines start at T-6.36 seconds.
- An issue appears after the handover to the automated launch sequencer.
- The clock stops at T-40 seconds, before the handover.
The steps
- Confirm the core stage is on internal power since T-1 minute 30 seconds and the upper stage entered terminal countdown mode at T-1 minute 20 seconds.
- T-50 seconds: end upper stage liquid hydrogen replenish.
- T-33 seconds: the ground launch sequencer sends the "go for automated launch sequencer" command.
- T-30 seconds: the core stage flight computer passes to the automated launching sequencer.
- T-12 seconds: start the hydrogen burn off igniters.
- T-10 seconds: the ground launch sequencer sends the command for core stage engine start.
- T-6.36 seconds: the RS-25 engines start up.
Safety rules that stop the station
- After the handover to the automated launch sequencer, any issue that stops the countdown ends the launch attempt for that day.
- Before the handover, after T-1 minute 30 seconds, the count can still recycle to T-10 if enough window is left.
To pass
- The handover at T-33 seconds and each command of the last seconds on time.
- A stop after the handover ends the day's attempt; a stop before it recycles to T-10 only with window left.
Official source
NASA · Artemis II launch day
Artemis II Launch Day Updates
NASA publishes its Artemis II launch day updates free: the last seconds of the countdown and what happens if the count stops after the handover to the automated sequencer.
Making Synapses is not affiliated with, sponsored by or endorsed by NASA, the FAA, the Canadian Space Agency or any launch provider. Agency, mission and program names are named only to describe the content.