PARIS — The space ministers of France, Germany and Italy are scheduled to meet Sept. 23 in Zurich to assess how far they are from agreement on strategy and funding for Europe’s next-generation Ariane rocket, upgrades to the light-lift Vega vehicle and — as a lower priority — their continued participation in the international space station.

The meeting should give these governments a better sense of whether a formal conference of European Space Agency ministers scheduled for Dec. 2 in Luxembourg will be able to make firm decisions, or will be limited to expressions of goodwill.

France, Germany and Italy account for most European space spending, and they are the three biggest backers of Europe’s launch vehicle and space station programs.

After working through the summer, officials from the three governments and from the 20-nation ESA — pushed by an emerging consensus among industrial contractors and Ariane rocket customers — appear to have settled on an Ariane 6 design that meets the strategic and financial requirements.

Ariane 6, like the Ariane 4 rocket retired in the late 1990s and replaced by the heavy-lift Ariane 5, will start with one version — a common core with a first stage powered by the Vulcain 2 cryogenic engine, an upper cryogenic stage powered by the Vinci engine, and flanked by as many as four solid-rocket boosters, depending on mission requirements.

It is not an entirely new rocket. The Vulcain 2 engine was developed for Ariane 5. The Vinci upper-stage engine was developed for an upgraded Ariane 5, called Ariane 5 Mid-life Evolution, that now appears less likely to win final funding approval at December’s ministerial conference.

The Ariane 6 solid-rocket stages, each carrying 120,000 kilograms of propellant, will share development costs with the Vega rocket. The new stages, called P120, will power the first stage of the Vega Consolidated (Vega C) vehicle awaiting government approval.

With so many elements borrowed from other programs, the Ariane 6 could be operational as soon as 2019 or 2020 — just a year or two later than the Ariane 5 ME — at a cost that government officials said would be around 3 billion euros ($3.9 billion).

Ariane 5 ME’s development cost has been estimated at 1.2 billion euros. With self-imposed spending limit on rockets of 8 billion euros over 10 years, ESA likely cannot afford to build both Ariane 5 ME and Ariane 6 at the same time. The 8-billion-euro ceiling includes all launcher spending at ESA, including ESA’s share of Ariane 5 and Vega operations.

Ariane 6’s operating cost, once production reaches its cruise-phase, would be some 90 million euros with four strap-on boosters, and be able to lift 11,000 kilograms of payload into geostationary orbit, the destination of most telecommunications satellites.

The lighter Ariane 6, with per-vehicle production costs estimated at 80 million euros, would be used for European government missions, ultimately replacing the Europeanized Russian Soyuz rocket that is operated from Europe’s Guiana Space Center on the northeast coast of South America.

The differences of opinion about Ariane 6, whose design configuration has changed at least twice in the past year, have so preoccupied French, German and Italian government discussions that they have had little time to think about the international space station.

“The station has really not been on the agenda at these meetings,” one government official said. “Set alongside the debate over launch vehicles, it doesn’t exist. But obviously it needs to be addressed, once the launcher issues are settled.”

Pleading empty pockets, Italy sharply reduced its space station contribution in 2012. Germany picked up the tab, with a small assist from Britain. German officials, who in recent years have been the station’s biggest European supporters, have insisted they will not do so again.

If other governments cannot commit to operating the station, German officials have said, then so be it.

Government officials have said it is all but inconceivable that ESA ministers will opt out of the station before 2020, especially since they have already started investing in a service module for NASA’s Orion crew-transport vehicle.

The service module is designed to cover ESA’s share of the station’s common operating costs at least to 2020. But only half the funds needed for it have been allocated. The remaining half awaits the ministerial conference.

Space station proponents in Europe are counting on the push of embarrassment that would follow a European departure, rather than the pull of enthusiasm for the space station, to force ESA governments to find the necessary resources to remain in the station partnership to 2020 and beyond.