Introducing EPCU S5B

If the schedule is met, MSG-3 is planned to move by end of May from EPCU S5C (where it is now tested) to S5B where it will be fuelled. The fuelling is for a satellite equivalent to go to a pump station for car. The difference being in the type of fuel to be delivered and the associated hazards linked to fuelling operations.
Hereunder is an external view on the EPCU S5B (fuelling) building at the CSG.

MSG propulsion, like many other spacecrafts and rockets, is achieved by a classical bi-propellant system, i.e. the combustion of two components: a liquid fuel with a liquid oxidizer.

For MSG-3 the fuel is the  Monomethylhydrazine (MMH) and Mixed Oxides of Nitrogen (MON) the oxidizer.
These two substances should NEVER EVER be in direct contact except in the combustion chamber of the rocket or satellite engines.Therefore, as showed by the picture below, the handling of these two substances follows physically separated routes: one on the right for the MON and another one on the left for the MMH.

At the moment, MSG "drums"containing these two propellants are still in a remote fuel farm (also called ZSE for Zone Stockage d'Ergol).
The S5B facility which has now been accepted for MSG-3 fuelling is now under preparation for performing this operation.

Inside S5B clean hall, Thales staff is validating a special device called DMRP  i.e. Dispositif Mobile de Remplissage et de Presurisation (Fill and Drain Cart). Note there is one cart for the MON and one other for the MMH.

The view below gives an idea of the area where the tank filling will be made. After a transfer from the airlock through the door into the clean hall with a crane, MSG-3 will be put in the middle on the fuelling stand. On the opposite side of the clean hall the MON and MMH rooms will accomodate drums. After being weighted, the MON drum will enter the clean hall the first. When the MON filling is completed, MMH filling will take place. In between decontamination operations is carried out in order to remove any residues of these (extremely) toxic substances inside the facility as well as in the filling material.

The fuelling stand on which MSG-3 will be installed for the fuelling

The propellant team will operate with SCAPE suits (a kind of diving suit) in 4 hour session shifts. The limitation is made by the battery of the radios. Before to don-off  their filling gear, operators have to take a shower. Facilities are foreseen just next to the filling hall.

Before and after the fuelling, the spacecraft is powered on, there fore a cooling device in necessary for the battery. The MICE used in S5C (see previous message), becomes an ICE (for Indoor Cooling Equipment) as it is built-in the facility and no longer a mobile device.

Once the fuelling is made, the SC will move to another area: the BAF (Batiment d'Assemblage Final or Final Assembly Building). At this moment the launch campaign turns into a new phase. The mating on the rocket is getting closer... but we shall let that open for further reporting :-)