SpaceBuilt-in hold: checks and fixes
A built-in hold is a planned pause written into the countdown. The clock stops, the launch time does not move, and the team uses the time to check the vehicle's health, review the data and fix small issues. You run the holds of launch day as NASA ran them for Artemis II, from the hold before tanking to the hold at T-10 minutes.
Free to startScenarios
- The built-in hold before tanking, after the air-to-gaseous nitrogen changeover and cavity inerting.
- The planned 1-hour 10-minute hold, with every cryogenic stage in replenish mode.
- The T-10 minute hold is extended to give engineers time for the final preparations.
The steps
- Stop the clock at the planned built-in hold; the launch time stays where it is.
- Run the final configuration checks and review the health of the systems.
- Review the data from cryogenic loading, propulsion systems and communications against the safety and performance criteria.
- Confirm all the launch criteria are met.
- Use the hold to resolve minor issues without impacting the overall timeline.
- Keep the propellant at flight-ready levels: in replenish mode the tanks are topped off as the super-cold propellant boils off.
- When the hold ends, resume the count with the next phase, as Artemis II resumed with the crew's arrival at the pad.
- If the hold at T-10 minutes needs more time, extend it and set a new liftoff time inside the launch window.
Safety rules that stop the station
- An extended hold must leave the new liftoff time inside the launch window, two hours long for Artemis II.
To pass
- Every check of the hold done and the launch criteria met before the clock resumes.
- Minor issues resolved inside the hold, without moving the launch time.
- The count resumed on time with the next phase, or a new liftoff time set inside the window.
Official source
Artemis II Launch Day Updates
NASA publishes its Artemis II launch day updates free: each built-in hold, what the teams did during it and how long it lasted.
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