ESA Confirms Ariane 6 Turbopump Fault, Fewer Launches

The European Space Agency (ESA) confirmed for the first time on September 21 that the launch schedule for its Ariane 6 rocket has slipped. An ESA spokesperson responded to a question from the European Spaceflight news site about reports that a turbopump fault had been found on one of the rocket’s engines, marking the agency’s first official acknowledgment of a problem that had, until then, been reported only on the basis of industry sources rather than ESA itself.

The story first broke on September 17, when the French outlet La Tribune reported that a rocket component required additional checks that could disrupt the launch schedule through the end of 2026. A day later, Peter B. de Selding’s Space Intel Report specified that the component in question was a turbopump, adding that the fault had been discovered during ground testing in August. According to that report, Arianespace might manage only one or two more flights this year, instead of the three or four originally planned. ESA did not comment on those claims until September 21, and it still has not disclosed what caused the fault.

Ariane 6 carries four turbopumps across two liquid propellant engines: the Vulcain 2.1 on the core stage and the Vinci on the upper stage. Each engine has one turbopump for liquid oxygen and one for liquid hydrogen. The oxygen turbopumps are currently built by the Italian company Avio, while ArianeGroup manufactures the hydrogen turbopumps. Under a December 2024 decision by ESA member states, production of the oxygen turbopumps is meant to move to an ArianeGroup plant in Vernon, France, but that transition has not been completed, so Avio is still supplying the parts. As of September 21, it was not known which of the four turbopumps was affected.

The ESA spokesperson kept the statement to a single line.

“ESA is aware of the delays.”

The spokesperson gave that line to European Spaceflight without commenting on the cause of the fault.

ArianeGroup and Arianespace, in a joint statement to the same outlet, confirmed that this year’s mission schedule would need to be adjusted.

“Industrial ramp-up of Ariane 6 production is proceeding smoothly. However, we will need to adjust this year’s mission schedule.”

The companies did not specify whether the additional checks now underway on the Ariane 6 production line relate to the reported turbopump fault, nor did they say when those checks are expected to end.

Arianespace had planned eight Ariane 6 launches for 2026. Four have flown so far, the most recent on August 27, when Ariane 6 carried the Eumetsat MTG-I2 weather satellite to geostationary transfer orbit. Engineers at the Guiana Space Center in Kourou, French Guiana, are now assessing whether the damaged turbopump can be repaired on site or needs to be shipped back to Europe for further inspection. If it can be fixed in Kourou, the remaining launches scheduled for late 2026 could still go ahead as planned. If the turbopump has to go back to Europe for rework, those missions would slip into early 2027.

How many launches will Ariane 6 have left in 2026?

Sources disagree on the exact number, though all point to a lower total than originally planned.

• Space Intel Report writes that 2026 could end with no more than six launches in total.
• SatNews reports that the total number of missions this year will be limited to five or six.
• European Spaceflight, citing Space Intel Report, writes that one or two more launches beyond the current four could still happen by year’s end, rather than the three or four once planned, which likewise points to a total of five or six.

The difference is mostly a matter of phrasing rather than substance: none of the three outlets now consider the original target of eight launches in 2026 achievable.

What ESA has not confirmed is the cause of the fault, which of the four turbopumps is involved, or whether the additional checks on the production line are directly tied to the fault discovered in August. Arianespace has not responded to media questions about the fault itself, and the agency has yet to publish an official, revised launch schedule for the rest of 2026. ArianeGroup and Arianespace are not publicly questioning the program’s goal of reaching nine to ten Ariane 6 launches a year by 2027, but how many launches 2026 ends up with depends on findings that have not been published yet.