ESA contemplates remedying Ariane 6’s shortcomings by converting it into a Franken-rocket

Bruno Le Maire, the former French finance minister, remarked in 2021 that the Ariane 6 was a “poor strategic decision.” More recently, in October of last year, the head of ESA warned that Europe’s space industry must “catch up” with international competitors like SpaceX and develop a reusable launcher “relatively fast.”

In its submission to ESA’s BEST! initiative, ArianeGroup suggests swapping Ariane 6’s solid-fueled side boosters for new liquid-fueled ones. The boosters would be developed by MaiaSpace, a French ArianeGroup subsidiary working on its own partially reusable small satellite launcher. MaiaSpace and ArianeGroup would adapt the Maia rocket’s methane-fueled booster for use on the Ariane 6.

Isar Aerospace’s concept for a reusable first stage booster (left) and ArianeGroup’s proposal for an Ariane 6 rocket with reusable strap-on boosters (right).

Credit:
ESA/Isar Aerospace/ArianeGroup

ArianeGroup’s proposal was first reported by European Spaceflight, which said the concept shown to ESA is similar to a 2022 ArianeGroup idea that described the liquid reusable boosters as a “plug-and-play” alternative to Ariane 6’s solid-fueled strap-ons, intended to cut operating costs and raise launch cadence.

The specifics of ArianeGroup’s latest plan haven’t been released, but the concept was summarized in a paper presented at the European Conference for Aeronautics and Space Sciences in 2025.

Isar Aerospace, a German rocket startup, won a separate BEST! contract from ESA to study a demonstrator for a reusable first stage based on the company’s light-class Spectrum rocket. The Spectrum vehicle was initially designed to be expendable. Its first test flight last year failed, and Isar is preparing a second Spectrum for another launch attempt later this month.

ESA asked ArianeGroup and Isar Aerospace to evaluate the feasibility of their concepts, prepare technology and system development plans, and outline schedules and costs for a “major flight demonstration.”

MaiaSpace’s launcher won’t fly until 2027 at the earliest, and any decision to base new Ariane 6 boosters on it is unlikely to produce results until well after Maia’s own flight. Even if ESA and ArianeGroup follow that path, the Ariane 6 would remain largely expendable.