A lot happens before an Ariane 6 rocket takes off, especially in the last hours before launch.

The start of an Ariane 6 liftoff countdown happens around 10 hours and 31 minutes before liftoff. Two hours after that, the mobile gantry – a huge hangar surrounding the rocket during its assembly on the launch pad – is rolled away, giving Ariane 6 the space it needs to liftoff.

The ground pipes that supply the rocket with its propellants are chilled slowly to avoid stress on the system – liquid hydrogen flows at –253°C! When the ground pipes are at temperature the upper and core stages are filled with propellants. Then it’s time for the pipes in Ariane 6’s main engine, Vulcain 2.1, to be chilled.

Final weather checks are performed before an automated sequence starts, on the last second before leaving the ground, the rocket is autonomous, no longer needing ground control and… Liftoff!