Extreme insulation for Ariane 6
It takes 180 tons of fuel to launch an Ariane 6 rocket into space. The cryogenic fuel consists of high-energy liquid oxygen and liquid hydrogen. These substances maintain their aggregate state only at very low temperatures – minus 200 °C (-328 °F) and minus 253 °C (-423 °F) respectively. The challenge is to keep these temperatures constant during the rocket's ascent and mission – otherwise they become gas again and endanger the expedition. It is very difficult to maintain these very low temperatures inside the rocket because during flight in the Earth's atmosphere, the surface of the rocket sometimes is subject to extreme heat of several hundred degrees Celsius.
Two new processes in development
The ArianeGroup in Bremen has developed new insulation technologies that offer optimal thermal protection and at the same time can be applied to the tanks in a more environmentally friendly, faster and thus more cost-effective way. Two completely new processes are currently planned for Ariane 6. First, laser surface treatment (LSI): in this process, lasers clean and smooth the surface of the rocket tanks with unrivaled quality, so that insulation material applied later adheres perfectly to the tanks even under the extreme conditions in space. So far, solvents have been used for this in a chemical process.
Secondly, a newly developed thermal protection called external thermal insulation (ETI) will also be applied. Robots spray the special PU foam fully automatically onto the surfaces of the tanks, followed by milling work, which ensures accessibility for subsequent work inside the tanks.
Future of the European launch vehicle
The new insulation technologies play their part in making Ariane 6 much cheaper and faster to build. For example, ETI replaces several insulation materials previously used, which considerably reduces the number of work steps required. Both the foam used and the LSI process are environmentally friendly and generate virtually no industrial waste – expensive disposal is no longer necessary. Overall, insulation costs are reduced by about half compared to Ariane 5. And the new, significantly more efficient technologies will also help to ensure that 12 Ariane 6 rockets can be built each year in the future – a maximum of only seven Ariane 5 launch vehicles can be delivered annually.
The innovative insulation processes are also highly interesting for application in other areas. For shipping, for example: the first cruise ships are using an environmentally friendly liquefied natural gas (LNG) propulsion system that, like the Ariane 6, requires perfect, cost-effective insulation of their tanks that can be produced in series. In enabling this, the ArianeGroup developers also support the green revolution for the world's oceans.
The development of the new technology is currently nearing completion. A first Ariane 6 tank has already been subject to the process. Further pilot applications will follow soon before the processes are actually used in the production of the first Ariane 6.