PARIS — The German government has agreed to drop its demand that Europe develop a long-planned upgrade of today’s Ariane 5 rocket and instead proceed with a new-generation Ariane 6 that borrows heavily on Ariane 5 technology, Germany’s space minister said.

The decision ends an impasse that has bedeviled the European Space Agency for more than two years as it prepares for a Dec. 2 conference of its governments.

While noting that certain funding details and a clarification of industry’s risk-taking guarantee remain to be ironed out, Brigitte Zypries said Germany and France now agree to back Ariane 6 and to scrap the Ariane 5 Midlife Evolution (ME) rocket that European governments have been developing for several years.

“We have found a compromise that is OK for both countries, for the other participating states and also for industry,” Zypries said in a Nov. 15 emailed response to SpaceNews questions. “The important elements are the joint intention to develop a new launcher as part of a concept based mainly on Ariane 5 ME technology and Vega, and a new launcher governance.”

Vega is the Italian-led small-satellite launcher. A Vega upgrade, along with Ariane 6, Europe’s participation in the international space station and a European Mars exploration project will all be on the table at the ministerial conference in Luxembourg.

The debate about future Ariane 5 investment has been the major roadblock to an agreement on all these subjects. Germany had said the Ariane 6 business model, industrial work-share distribution and the role of Ariane manufacturers in assuming market risk all were too ill-defined to permit a full-scale go-ahead.

Zypries is Germany’s parliamentary state secretary in the Federal Ministry for Economic Affairs and Energy, and the government’s coordinator for aviation and space policy.

Her French counterpart, Genevieve Fioraso, who is state secretary in the French Ministry for Higher Education and Research, alluded to a French-German agreement in a briefing with journalists Nov. 12.

Fioraso and Zypries met Nov. 13 in Cologne, Germany, with ministers from Italy and several other governments.

Germany had said the Ariane 5 ME, which is basically today’s Ariane 5 with a new, multi-ignition upper stage and about 20 percent more power, is a much lower-risk endeavor and should be approved before any commitment to Ariane 6.

France had argued otherwise, first by proposing a solid-fuel-based Ariane 6 that found little support in industry or among commercial satellite fleet operators — the main customers for today’s Ariane 5 — and then by aligning with a proposal by Ariane prime contractor Airbus Defence and Space and motor-maker Safran on Ariane 6.

The Ariane 6 comes in two models: an Ariane 62 that would be used mainly for government missions to medium- and low-Earth orbit, and a heavier Ariane 64 with solid-rocket boosters that would share technologies with the enhanced Vega rocket.

The new Ariane 6 program model, as described by ESA Director-General Jean-Jacques Dordain in an Oct. 29 response questions from Germany, would force industry to assume the risks associated with the commercial market, meaning no more annual government support payments to permit the launch services business to make ends meet.

In return, European governments would guarantee an average of five launches per year using Ariane, at set prices, to allow industry enough business to attack the commercial market on its own.

The new Ariane 6 approach thus represents a climb-down from the earlier positions held by both the French and German governments, and by ESA, whose governments in late 2012 agreed to fund initial studies of the now-scrapped, solid-fueled Ariane 6 design.

The Ariane 6 rocket would be ready for an inaugural flight in 2020.

ESA has proposed to spend 8 billion euros ($10 billion) in total on launchers beween 2015 and 2024, including some 4.3 billion euros on Ariane 6, including a new launch pad at Europe’s Guiana Space Center spaceport in French Guiana. The price-support payments, which now average some 100 million euros per year, could continue until Ariane 6 is operational.

Zypries said Germany would insist that the 10-year commitment, which ESA has proposed be divided into payments to be released only after industry has reached certain milestones, be subject to a review at the next ESA ministerial conference, scheduled for 2016.

France has said it would finance 50 percent of Ariane 6’s development. The German contribution is expected to be around 20 percent, with Italy and a handful of other ESA governments paying the rest.

With the key strategic issue now settled between France and Germany, governments and industry will focus on several outstanding questions related to Ariane 6. Among them: What happens if governments cannot maintain a five-per-year launch rate for their own satellites? Does industry then have a right to demand support payments as it battles Space Exploration Technologies Corp., also known as SpaceX, of the United States, Russia’s Proton and other rockets on the commercial market?

“Governance, meaning the share of risk between public and industry, needs some more work,” Zypries said.

European governments have not yet firmly committed to maintaining their share of international space station work through 2020, although they agree that 2020 is all but certain. Beyond 2020 — NASA wants to operate the facility through 2024 — is an open question.

In 2012 Germany agreed to increase its share of total European space station funding following the collapse of Italy’s contribution in the face of the financial crisis in Italy. France also has hesitated on space station support, and German officials have said Germany will no longer provide a financial backstop for other nations’ station roles.

Zypries said Germany, France and Italy, Europe’s top three station backers, have reached an unwritten understanding that all of them will return to the space station percentage shares they agreed to in 1995 at an ESA ministerial conference in Toulouse, France.

“We underlined that the compromise includes the funding of the space station as the ESA executive has proposed, meaning the Toulouse key,” Zypries said. “France and Italy did not object, which we take to mean that they have the same understanding.”

The Italian-led ExoMars program, a two-launch mission in 2016 and 2018, meanwhile, remains short of needed financing by around 200 million euros. Zypries said no decisions were reached on this program, but that “Germany proposed to offer some in-kind contribution” beyond its agreed-to financial contribution level.