Under pressure

With the launch of Sentinel-3A confirmed for 16 February, preparations for liftoff are charging full speed ahead. The tricky task of fuelling the satellite has now been ticked off the ‘to do list’ and the propulsion team is already decontaminating their equipment before returning home.

Official confirmation of the new launch date had to come before the team could start this delicate operation. The hydrazine fuel is extremely toxic so only a few specialists remained in the cleanroom during fuelling. A doctor and security staff waited nearby with an ambulance and fire engine ready to respond to any problems.

Thumbs on the fuelling front. (ESA)

After fuelling, the tank was pressurised to an ‘intermediate level’ and left to stabilise overnight. The following day, the team gradually increased the pressure to the required level of 20.5 bar.

ESA’s Sentinel-3A launch campaign manager, Kristof Gantois, said, “We are really happy to have passed this important milestone. The Thales Alenia Space propulsion team and our propulsion expert executed this challenging task brilliantly.”

Upon confirmation that there were no hydrazine traces in the air, the fuelling lines could be disconnected and the decontamination phase started.

The fill and drain valves have been closed, torqued to the flight value and wire-locked. The drum with the remaining hydrazine has been moved, ready to be taken out of the cleanroom and back to its container.

Suited for fuelling. (ESA)

The feedthroughs between the cleanroom and the electrical ground support equipment room have been unsealed.

The decontamination phase involves decontaminating of all of the equipment that has been used for the fuelling operation. This means ensuring that the equipment is hydrazine-free at the level of 0.1 part-per-million before the equipment is packed, ready for shipment back to Europe.

This activity will last few days before being completed, but it will be carried out in parallel with other activities.

On the launcher side, the Breeze stage was prepared for fuelling today it will be brought to the fuelling station. All the activities are so far fully nominal.

Today is the last day of our ‘stand alone’ activities, which will mainly focus on finalising the configuration of the satellite before the ‘combined operations’ of mating it to the launch vehicle adapter.

A small team will also go to the vault to do a last check on the links between the vault and the launch tower.

The hotel in Plesetsk is fully booked again with arrival reinforcements and there is an air of excitement as we are now fast approaching launch!

Weather in Plesetsk: –2 to –4 °C, partially cloudy with some light snow.

For information about our Sentinel-3 mission visit www.esa.int/sentinel-3

From the ESA Sentinel-3A team at the Plesetsk cosmodrome in Russia.