Keeping Herschel cool before launch

A helium vent connected to the fairing of the Ariane 5 in the final assembly building in the launch site on 12 May 2009. The Herschel cryostat will be flushed with helium until the day before launch when the cryostat will be closed, the vents and auxiliary connections removed, and the doors of the fairing shut. This process keeps the cryostat and the instruments as cool as possible.