Amy Svitak Paris

After six months of back-and-forth, and with a key budget meeting fast approaching, France and Germany staked out a modest but crucial piece of common ground last month: In the debate over whether to start work on Europe's next-generation launch vehicle, the tab for building a successor to the Ariane 5 will run €3.8-5 billion ($5-6.5 billion) over a decade.

The agreement between the French and German space agencies, however, is just the beginning. Detailed in a report delivered to their respective governments in recent weeks, the cost estimate is only a point of departure from which the often polarized partners will move forward this fall, when European Space Agency (ESA) ministers meet in Caserta, Italy, to settle the organization's multi-year spending program.

At stake is France's continued support for key ESA programs, including the International Space Station (ISS), Europe's next-generation polar-orbiting weather satellite and an ambitious proposal to send robotic probes to Mars before the decade's end—all of which could be compromised if ESA presses ahead with development of the next-generation launch vehicle the French have tentatively dubbed Ariane 6. As the primary financial load-bearer for Europe's Ariane family of rockets, France is considering a proposal to scrap current Ariane 5 modernization efforts and go straight to development of the next-generation launcher. But as ESA's largest financial contributor, along with Germany, it is unclear whether France can pay the lion's share of Ariane 6 development without jeopardizing its contributions to other ESA programs.

“It should not be that we come out of the ministerial with only one program that is called the new launcher,” says Johann-Dietrich Woerner, chairman of the German Aerospace Center DLR. “We have to pay for Earth observation, the barter element for the ISS, and ExoMars, so my opinion is the ESA governments are not ready to pay the majority of their money just for a new launcher.”

Germany, which favors continued work on an upgrade to the current Ariane 5, known as the Ariane 5 Midlife Evolution (Ariane 5ME), argues that tandem development of both vehicles would only cost a bit more than continuing with Ariane 5ME alone. Woerner says synergies between the two rockets' industrial teams could cover as much as 25% of the cost to develop and produce the Ariane 6.

Woerner says going straight to Ariane 6 raises questions about industrial work share, and that it remains to be seen whether the new launcher will end roughly €120 million in annual ESA support payments to Arianespace, the commercial launch consortium that operates Ariane 5. Despite going almost a decade without a failure—Ariane 5 boasts 50 straight successes and claims approximately 50% of the commercial launch market—Arianespace is unable to break even without continued financial backing from the space agency's member states.

Even if it does, another decade could pass before the Ariane 6 is operational, leaving ESA to foot the bill for continued price supports to the tune of €1.2 billion during development.