The European Space Agency has shelved planned "Block 3" upgrades to its Ariane 6 rocket, including a lighter carbon-composite ICARUS upper stage, in a decision that raises questions about the vehicle's long-term future despite a largely successful launch record. The cancellation affects some ESA science missions, including a planned probe to Saturn's moon Enceladus, and appears to reflect growing impatience among the European ministers who fund the programme over the rocket's high cost.

Ariane 6 has flown eight successful missions since its debut two years ago and can carry over 20 metric tons to low-Earth orbit, giving Europe independent access to space after it cut ties with Russian launchers and reduced reliance on SpaceX. However, each launch is heavily subsidised: Europe spent roughly 3.6 billion euros developing the rocket, and ESA director general Josef Aschbacher has confirmed governments must still pay 32–38 million euros per flight in subsidies on top of the 80–100 million euro cost customers such as Amazon are charged. ESA is aiming for nine or ten flights a year, with discussions ongoing about scaling up to 12, 15 or even 20 annual launches, and Aschbacher hopes for clarity from ministers on production plans by the end of the year.