MON fuelling started

On Saturday 16/06/2012, the preparation for the MSG-3 fuelling started in EPCU S5B hall as planned. The first propellant to be injected is the MON (the oxidizer). The corresponding drum has been moved from the storage room to the S5B clean hall as seen above on the right hand side under the crane.
The completion of the preparatory activities were related to the final connection of pipes and tubes from the drum to the spacecraft (blue caps) via the kart (Fuelling Ground Support Equipment).

On Monday 18/06/2012 the MON fuelling started. This hazardous activity is performed by a specialised group of people (called "ergoliers" in French) who perform in SCAPE suits (Self Contained Atmospheric Protective Ensemble). Their activity is monitored from a remote room through video, radio and data links. The few pictures below are taken from the monitor screens the only place where the fuelling can be witnessed. This explains their poor quality.

There are two teams of two staffs operating in four hour shifts. A total of 601,5 kgs of MON will be injected in two tanks. This will be achieved by six injections of MON today and two others tomorrow 19/06/2012. During these active phases, to prevent any mistakes, each fueller check the work of his colleague, under the supervision of the remote control room.

Stabilisation phases are necessary between injections to make sure that propellant quantity is equally split between the two tanks. During these stabilisation phases, fuellers are requested to remain in the S5B Main Hall. In this phase, they may take a rest to recover from the extremely exhausting (physically and mentally) injection phase. Here below one of the fueller is in resting position for his head, the weight of the heavy helmet being particularly tiring.

The weight of the remaining propellant in the drum is measured by mean of a load cell (with a back up) and can be permanently read. The exact quantity of propellant injected into the spacecraft is calculated in real time by deducting what is read to the known total weight of the propellant in the drum.

Note: the MMH read on the TV monitor does not mean that MMH propellant is fuelled but it is the identification of the two cameras (Monitoring Main Hall :-)