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Friday, 8 February, 2002, 18:19 GMT
Space diary from Kourou
European space experts are preparing to launch the Envisat mission to monitor the Earth for signs of pollution and climate change. Project manager Derek Todman is keeping a diary for BBC News Online.

1 February

Today we completed the Satellite Flight Readiness Review where we confirm and agree with the European Space Agency (Esa) that the satellite is ready for the next phase: fuelling.

It is a major milestone for the team. The review checks that we built the spacecraft correctly to drawing and that all the plans and procedures are in place for the remaining phases to launch.

2 February

Derek Todman of Astrium in front of Envisat (BBC)
Derek Todman in the clean room
Rehearsed the countdown for launch. We want this to run smoothly on the day and therefore before launch we rehearse the launch-day activities.

This was done successfully. We even simulated a few problems for the team to sort out. These were overcome and we would have been OK for launch.

3 February

Gave the team the day off as we have been working quite long hours to make sure we meet the launch date. Rained all day - now I know why they call it the tropical rain forest. When it rains here, it really does rain.

4 February

Start the preparation activities for moving the satellite from the integration hall to the fuelling hall. This involved fitting the last few blankets, the solar array "arm plugs". These complete the circuits so that the solar array can be released in orbit once the correct commands have been received.

Moving the spacecraft (Photo: Astrium)
Moving the spacecraft
The satellite is then finally rotated to the vertical orientation. The air skate was also moved into the integration hall.

The air skate allows the satellite to be moved on a cushion of air between the various clean rooms in the S5 facilities here at Kourou.

5 February

Moved the satellite from the integration stand to the air skate. It was then gently pushed down to the fuelling hall on the air skate.

The total mass is in the order of 16 tonnes and can be easily pushed by 10 people, most of whom are keeping it going straight.

This was for the team that watched it leave the integration hall a funny sort of day. For some, it will be the last time they see the satellite on the ground. Access to the satellite becomes very limited once it is fuelled as there are strict safety rules that must be followed.

The propulsion team in their suits (Photo: Astrium)
The propulsion team in their suits
It also made us all realise that this really is the start of the final preparations for launch. Once the satellite reached the fuelling hall it was transferred to the "simple stand" for the fuelling activities.

The tank of hydrazine, 350 kg, was also moved into the fuelling hall ready to start the fuelling activities.

6 February

The fuelling team carried out all the last minute activities in preparing for fuelling, mainly connecting up the satellite to the fuelling equipment, moving out of the area any unwanted equipment, and making sure all unused electrical equipment is turned off.

They then verified that the flow rates for filling are correctly set and checked again that the hydrazine we are loading is clean.

Map (BBC)
This is important as any particles in the fuel could stop the thrusters working in orbit.

It is a slow process now as the team that carries it out is dressed in protective suits which make it very awkward to do anything and therefore it tends to slow everything down to a snail's pace.

The launch preparation activities are not only here at Kourou, French Guiana; there are teams back in Europe at Mission Control Ground Centre in Darmstadt, Germany, practising commanding the satellite and monitoring the telemetry data to verify the satellite is operating correctly.

Today these teams had another practice session during which a number of faults were simulated which the teams successfully identified and corrected.

7 February

We have now completed filling two of the four hydrazine fuel tanks. The total fuel mass is 300 kg.

This is, as yesterday, a hazardous operation and has to be done in the protective suits and also everything has to be made safe at the end of the operation.

In the next instalment from Kourou: we complete fuelling this weekend. The satellite mates with the ACU (the interface ring between the satellite and the Ariane 5 rocket) and is moved to the BAF (the building where the Ariane is finally assembled and prepared for launch).





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