ESA’s Mission Director Marcus de Deus Silva sends the following update:
ATV-4 refuelling system purging has just taken place successfully. This is a standard operation, carried out after propellant transfer, which is necessary to prepare the refuelling system for ATV departure. Purging means that ATV expels the residual liquid propellant and helium pressurant from the pipes connecting it to the ISS. This was done by opening valves that vented the liquid and gas into the vacuum of space. The venting itself took just a few minutes, after which the vent valves were closed.
Tomorrow, 14 August, a second vacuuming of the refuelling system will take place. This will be the final major operation of the ATV-4 refuelling system.