Phoebus wires

Close up of the sensors and wires on the Phoebus rocket fuel tank demonstrator during testing.

Lightweight but super-strong. Extremely rigid or flexible and springy. Corrosion-resistant and ideal for complex shapes. All of these benefits come from carbon fibre, and when performance matters it is probably part of the package. Tennis rackets, bicycles, racing cars and airliners are just a few products that rely extensively on this miracle material.

It’s no surprise that modern rockets also perform better thanks to carbon fibre. More formally known as CFRP – carbon fibre reinforced plastic – this mix of super-strong carbon fibres and the binding resin that holds them in place is a great way to reduce the mass of a rocket, and so increase the payload mass it can carry. Ariane 6 and Vega-C both carry CFRP payload fairings, and the body of the P120C solid-fuel rocket motor that serves as Ariane 6’s boosters and the first stage of Vega-C is one of the world’s largest single-piece CFRP structures.

But can CFRP go further, and replace the metallic structures in a rocket’s cryogenic fuel tanks? That is the objective of ESA’s Phoebus programme, which aims to produce upper stage tanks and structures in carbon fibre – and so far it is acing its tests.