In order to provide the astronauts on the International Space Station with vital supplies, the European space ferry ATV (Automated Transfer Vehicle) is launched at regular intervals. As part of the supplies, there are water tanks containing potable water for the engineers. In the early years, these tanks were rubber lined.
The rubber lining of the tanks tainted the water so, in 2000, the task was set to find a non contaminating liner for the steel tanks which could be made to line an existing design of steel tank already developed by MAN Technologie (subsequently MT Aerospace).
In 2000 Man Technologie Germany turned to Holscot, who are well known as the leading European company for specialist FEP constructions, for help developing a unique FEP lining tank.
FEP was identified as the ideal material because it is completely inert and non contaminating. Additionally, being a true thermoplastic, it can be vacuum formed and welded.
The design of the new tanks was refined by using half sized, test model tanks, cycled over a range of fill and empty simulations.
The fabricated liners were thermoformed from Holscot’s own extruded FEP film. The film was vacuum formed in two parts and welded to form a circular tank construction. The top half of the tank was designed to pull down and expel the water under zero-g conditions. The lower half of the tank is bonded onto the tank’s inner shell. For this the FEP had to be externally treated using Holscot’s own proprietary etching process. Almost complete expulsion of the liquid was required. The stainless steel tank was then over wrapped with filament wound carbon fibre.
The first set of these very special tanks was integrated into the European space ferry ATV (Automated Transfer Vehicle) and successfully launched in 2008 by an Ariane 5 Heavy Lift Rocket, as part of the European Union contribution to the continuation of the International Space Station.
To date, 3 sets of these tanks have been integrated and sent to the ISS.
© ESA – A. Le Floc’h.
In time the tanks are back loaded with waste and released to fall back into the earth’s atmosphere and burn up. It is thought by Holscot that this is the first time such an FEP product has been made in this way and for this use. Holscot is proud to be chosen for this demanding application.