European governments declined to give the go-ahead for work to begin on European participation in Russia’s proposed Clipper manned space exploration vehicle after concluding that the project is not yet clearly defined, according to European government and industry officials.

The decision, made June 22 at a meeting of European Space Agency (ESA) governments in Darmstadt, Germany, nonetheless left the door open for a Euro-Russian cooperative effort to be considered by ESA government ministers at a meeting they have scheduled for December in Berlin, officials said.

Anatoly N. Perminov, head of Russia’s Federal Space Agency, Roskosmos, told ESA governments the week of June 15-17 in Paris that the winged Clipper spacecraft could be the centerpiece of a Euro-Russian cooperative effort in manned space.

The winged vehicle, which resembles some of the designs being considered by NASA for a Crew Exploration Vehicle, would carry six astronauts into space with a conventional rocket. It would return to Earth to land glider-style.

Design teams at RSC Energia outside Moscow, who conceived the project, say that in addition to carrying double the number of passengers compared to today’s Russian Soyuz capsules — six compared to three — Clipper could remain docked to the international space station for up to one year, compared to six months for Soyuz. Clipper’s current configuration envisions that the 13,000-kilogram crew transporter could be reused up to 25 times.

But Energia officials interviewed during the Paris air show said Clipper remains “a pre-project” that has not received much funding from Roskosmos, according to one Energia official, who added: “Discussions with Europe are still embryonic. Nothing is decided and it is not yet known what ESA’s involvement might be.”

Several European companies are participating in consortia backing two competing designs for NASA’s proposed Crew Exploration Vehicle. But European governments are not involved.

ESA officials have said their goal is to assure that whatever international space-exploration effort materializes to serve the international space station, and later lunar and Mars missions, it should not be dependent on a single crew-transport vehicle.

The dependence of Europe and Japan on the U.S. space shuttle for servicing the space station has made these nations determined not to repeat that mistake.

ESA officials had proposed to their delegations at the June 21-22 Darmstadt meeting that they approve what is known as an “enabling resolution” to prepare a proposal to be delivered to their ministers for formal review in December. This resolution was viewed as premature, according to government officials, and was not approved.

Daniel Sacotte, ESA’s head of manned space and space exploration, has said he hoped to persuade ESA governments in December that detailed studies of Clipper be started with Russia on a no-exchange-of-funds basis.

Peter B. de Selding was the Paris bureau chief for SpaceNews.