WASHINGTON — The European Space Agency is delaying the final flight of the original version of the Vega rocket because of a problem with the rocket’s upper stage.

During a Dec. 14 briefing after a meeting of the ESA Council, agency officials said the next and final launch of the Vega rocket, previously scheduled for the spring of 2024, has been delayed to September because of missing tanks for the rocket’s Avum upper stage.

The publication European Spaceflight reported Dec. 4 that two tanks built for the final Avum upper stage went missing from an Italian factory used by Avio, the prime contractor for the rocket, during a renovation of that facility. The stages were reportedly later found in a landfill, crushed and unusable.

“Avio has confirmed to ESA that there is an issue with tanks for the last Vega flight,” said Toni Tolker-Nielsen, ESA director of space transportation. He did not confirm the specifics about the tank issue but said the tanks had not been stolen. The new September launch date, he said, is based on a “workaround solution to these missing tanks.”

ESA and Avio considered two solutions. One was to use tanks originally built for qualification of the Vega more than a decade ago. That would have allowed a launch as soon as July. “But that solution is risky,” he said because the tanks could fail requalification tests before launch.

The option that the agency appears likely to follow is to use tanks for the larger Avum+ stage for the Vega C rocket. “It would necessitate some structural modification of the inner structure of the Avum,” he said. “It seems a good, feasible solution.” That approach would support a Vega launch in September 2024.

That final Vega mission was previously set to launch the Biomass Earth science satellite for ESA. It is now currently scheduled to launch Sentinel-2C, another Earth science spacecraft that is part of the Copernicus program. Simonetta Cheli, ESA’s director of Earth observation, said that ESA has not yet identified a new launch opportunity for Biomass.

The problem with the final Vega is separate from ongoing work to return the Vega C to flight after a launch failure nearly a year ago. The next Vega C launch is currently scheduled for between mid-November and mid-December of 2024, Tolker-Nielsen said, after two static-fire tests of the Zefiro-40 second stage of that vehicle with a redesigned nozzle.

Ariane 6 setback

Tolker-Nielsen also revealed at the briefing that there was a problem during a Dec. 7 test of the upper stage of the Ariane 6. That hot-fire test at a German facility was intended to analyze the performance of the upper stage in degraded conditions.

“Unfortunately we had an abort two minutes into the firing test,” he said. The cause of the abort is under investigation by ArianeGroup, the prime contractor for the rocket. The issue, for now, does not affect the schedule for the first Ariane 6 launch, announced for between June 15 and July 31 of 2024.

He said that another wet dress rehearsal of an Ariane 6 test model, called the combined test loading 3, remains scheduled for Dec. 15 at the spaceport in Kourou, French Guiana. That test will conclude with a brief firing of the core stage engine.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...