27 November: satellite fuelling

Having passed their fit check and functional tests with flying colours, the two Galileo satellites made their way to fuelling facility to be loaded with propellant.

Before adding fuel, the satellites underwent pressure testing to ensure they wouldn't leak any fuel. Only then is it safe to begin adding fuel.

The satellites are fuelled in a special facility, separate from other parts of the spaceport. To get there, they were once again packed into their transport containers.

Fuelling involves hydrazine, a propellant that is both toxic and explosive. For this reason, only a handful of specialists remain inside the cleanroom during the process, fully protected by their astronaut-like SCAPE suits (Self-Contained Atmospheric Protection Ensemble).

Once in orbit, 23 222 km above Earth, this fuel will propel the satellites to their final position and keep them precisely aligned.

A launch is a meticulous process where every step is planned well in advance. Fuelling must be completed early before the next major step: the satellites’ integration on the launcher.