Europe’s decision to continue work on a restartable upper-stage engine for the Ariane 5 launch vehicle removed the immediate threat of widespread job losses at Snecma, Europe’s biggest rocket-motor builder, company officials said.

But Snecma officials questioned whether the European launcher alliances forged with Russia and Ukraine will not undermine Europe’s own commercial-launch sector.

Paris-based Snecma, part of the Safran Group, has been able to secure a stable business for its Vernon, France-based rocket design teams following a December agreement by the European government ministers who oversee European Space Agency (ESA) spending to continue development of the Vinci engine.

Vinci would permit the current Ariane 5 ECA rocket to boost its payload capacity to 12,000 kilograms, an increase of about 2,000 kilograms. The new upper stage also would be capable of multiple ignitions once launched, permitting Ariane 5 to place satellites in different orbits. Work on Vinci was sharply cut in 2003 so the money could be spent instead on the Ariane 5 ECA program following a December 2002 launch failure that prompted an expensive redesign.

Both the Vinci development and funding for work to enhance the performance of the Ariane 5 ECA’s Vulcain 2 main-stage engine were approved by ESA government ministers when the met in December.

Safran Chairman Jean-Paul Bechat, addressing a press conference here Jan. 11, said the Vinci and other rocket-motor programs agreed to by ESA are sufficient to continue work at Vernon without the threatened layoffs.

“Our situation is a lot more solid than it was a few months ago,” Bechat said. “We have passed a period of great uncertainty. It’s still far from ideal, but it’s better now.”

Bechat said that beyond the launcher-research problem, the difficult commercial introduction of the Ariane 5 ECA rocket also was accomplished in 2005 with two successful launches as well as three launches of the proven Ariane 5G variant. The rocket is scheduled to fly next in mid-February, carrying two commercial telecommunications satellites.

Safran reported Jan. 11 that its Snecma space division, which includes work with Italy’s Avio S.p.A. on Ariane’s sold-fueled strap-on boosters and development of plasma-electric motors for satellites, posted sales of 538.9 million euros ($646.7 million) in 2005 — a 2-percent increase over 2004.

Michel Laroche, president of the company’s solid propulsion division, said five or six Ariane 5 launches per year and a recent reorganization giving the Safran-Avio Europropulsion joint venture more responsibility for the solid strap-on boosters should help stabilize the division’s revenues for the next couple of years. “But as is always the case, it’s the market for commercial satellite launches that will determine the pace of business,” Laroche said.

Safran officials in the past have questioned European governments’ decision to operate Russia’s Soyuz rocket from Europe’s equatorial spaceport, saying it could take business away from Ariane 5.

Joel Barre, Safran vice president for space motors, said that up until now the Arianespace commercial launch consortium, in which Safran is a 10-percent shareholder, has shown that the Soyuz business can be managed in a way that does not harm Ariane 5. But Barre said it still is not certain whether Europe’s Soyuz decision will live up to its promise of leading to a long-term partnership with Russia on future rocket designs.

Barre said the Soyuz agreement makes sense only if Russia and Europe ultimately join forces in the commercial-launch sector.

“The relationship with Russia should lead to a common development of vehicles,” Barre said. “We should share costs, risks and technology and then put commonly developed products on the market. This model has not yet been proven, and I can only note that today the biggest competitor to Ariane 5 is Russia’s Proton rocket. It’s hard to be competitors and partners at the same time.”

Barre said the same reasoning ultimately could apply to the Arianespace alliance with Sea Launch LLC of Long Beach, Calif., a Boeing Co. affiliate that markets the Russian-Ukrainian Zenit 3SL launch system.

The mutual-backup arrangement between Sea Launch and Arianespace so far has led to two Ariane 5 contracts being transferred to Sea Launch. Sea Launch has begun to market its Land Launch system — the same rocket, but launched from Russia’s Baikonur Cosmodrome in Kazakhstan rather than from a floating platform on the equator in the Pacific Ocean.

The Land Launch system, which in 2005 booked its first commercial orders, is aiming at the same class of commercial satellite as the Soyuz vehicle to be operated by Arianespace.