The €50 million agreement – a rider to an earlier contract for design studies – will demonstrate the feasibility and benefits of carbon-fibre tanks and structures applied to high-impulse hydrogen and oxygen cryogenic propellants. The agreement was signed in Bremen, Germany by ESA Head of Future Space Transportation Rüdeger Albat, on behalf of ESA Director of Space Transportation Daniel Neuenschwander, and Karl-Heinz Servos, head of ArianeGroup’s Industry Directorate.

These so-called “black stages” – named after the distinctive colour of carbon fibre structures – could become a feature of future European rockets. The weight reduction offered by a Phoebus stage could increase payload performance by up to 2 tonnes – with the added benefit of lower production costs compared to traditional metal structures.

Phoebus is also an important step on the way to reusable upper stages, which require ultra-lightweight tanks for green propellants.