Purging the pipes

ATV-5 approaching Station in August. Credits: Roscosmos-O. Artemyev

Another update from ATV Control Centre on ATV-5’s last fueling operations in space: Fuel purging took place Wednesday morning. The reason we need to do this is to prevent propellant liquid escaping when ATV Georges Lemaître undocks from the International Space Station at the end of its mission. The purging operation safely emptied the propellant liquid remaining in the lines between ATV-5’s tanks and the Space Station, including the connectors in ATV’s docking ring, into the vacuum of space. This followed on from yesterday’s refuelling propellant transfer activity.

Today we opened the oxidiser propellant line vent valves for a second time to expel any residual gas and liquid remaining after yesterday’s purging thus concluding ATV-5 refuelling operations. The final operation was “Second Vacuuming” which finished at lunch time. During this operation the venting valves of the refuelling oxidiser transfer lines were opened for about 90 minutes. This expelled a small amount of residual gas and liquid in these lines which remained after yesterday’s purging activity. The valves have now been closed and propellant transfer lines are now completely empty meaning that it is safe for ATV to undock from the space station.