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SpaceLaunch countdown: from tanking to liftoff: Everything nominal: the count runs straight to T-0
Everything nominal: the count runs straight to T-0. A crewed rocket is on the pad. You run the countdown with the launch team: the go to load propellant, the crew sealed inside, the hatch checks, the flight termination system, the launch director's poll, the terminal count and the handover to the automated sequencer at T-33 seconds. It follows the countdown NASA ran for Artemis II, the crewed flight around the Moon.
Free to startThis scenario
- Everything nominal: the count runs straight to T-0.
The steps
- About 10 hours 50 minutes before launch, the launch team decides go or no-go to begin tanking.
- Chill down the lines and engines, then slow fill and fast fill the core stage with liquid oxygen and liquid hydrogen.
- Bring the crew to the White Room: communication checks and suit leak checks.
- Close the crew module hatch and the launch abort system hatch, with seal pressure decay checks; even a single hair can stop a hatch from closing.
- The closeout crew leaves the pad and the launch control team takes over the count.
- Confirm the flight termination system works: it lets the ground destroy the rocket if it veers off course, to protect the public.
- The launch director runs the go/no-go poll: a unanimous go is needed to enter terminal count.
- At T-10 minutes the ground launch sequencer starts the terminal count.
- T-6 minutes: go for core stage tank pressurization; T-4 minutes 30 seconds: flight termination system armed; T-4 minutes: auxiliary power unit start.
- At T-33 seconds the sequencer sends go for automated launch sequencer.
- T-10 seconds: engine start command; T-0: booster ignition, umbilical separation and liftoff.
Safety rules that stop the station
- Between T-6 minutes and T-1 minute 30 seconds, a hold can last up to 3 minutes; longer, the count recycles to T-10.
- After T-1 minute 30 seconds and before the automated sequencer, the count can recycle to T-10 only if enough window is left.
- After the handover to the automated launch sequencer, any stop ends the launch attempt for the day.
To pass
- A unanimous go in the poll before the terminal count.
- Every step on time and liftoff inside the launch window, which was two hours for Artemis II.
- The team can hold at T-6 minutes for the rest of the window without recycling.
Official source
NASA · Artemis II launch day
Artemis II Launch Day Updates
NASA publishes its Artemis II launch day updates free: every countdown milestone, the poll and the hold rules.
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