BERLIN — An initial design review of a new, more-powerful upper stage for Europe’s Ariane 5 rocket has concluded that the stage is too heavy to deliver the required performance, according to European government and industry officials.

One official said the evaluation, called the Stage and System Concept Review and conducted at Astrium Space Transportation’s Les Mureaux, France, facilities the week of June 4, is almost certain to revive questions about whether the proposed Ariane 5 Mid-life Evolution (Ariane 5 ME) investment is worthwhile.

European government officials have been debating for more than a year whether spending some 2 billion euros ($2.4 billion) on Ariane 5 ME, which likely will not be in service before 2017, should be scrapped in favor of proceeding directly with a next-generation rocket that ultimately would replace Ariane 5.

The debate remains sensitive as some in Europe, notably the German Aerospace Center, have made strong endorsements of Ariane 5 ME and said they are not prepared to discuss an Ariane 5 replacement at this point.

The 18-nation European Space Agency (ESA) in November 2008 agreed to continue work on the Ariane 5 ME upper stage, notably its Vinci restartable engine, through 2011 with a budget of 357 million euros.

Vinci, developed by Snecma Motors, a division of Paris-based Safran, has been in development for a decade but has suffered from gaps in funding, notably in 2002 as Vinci funds were transferred to current Ariane 5 issues following a launch failure.

In December, ESA awarded Astrium Space Transportation, Ariane 5’s prime contractor, an Ariane 5 ME system-design contract valued at 157 million euros, which was drawn from the budget approved in late 2008.

Government officials, in approving the 2008 investment, said they would decide in 2011 or 2012 whether to proceed with full development of the Ariane 5 ME stage, which they estimated would cost an additional 1.5 billion euros.

The Stage and System Concept Review was intended as a six-month checkup on the work.

Equipped with the new Vinci upper stage, the Ariane 5 ME would be able to carry two commercial telecommunications satellites weighing a combined 12,000 kilograms into geostationary transfer orbit, compared with around 9,000 kilograms for the current Ariane 5 ECA vehicle.

The performance improvement would make it much easier for the Arianespace launch consortium of Evry, France, to find two compatible satellites without having to worry about bumping into the vehicle’s performance ceiling, especially since satellites weighing 5,000 kilograms have become standard in the commercial market.

But the French government is also beginning early designs for a new Ariane rocket that would carry only one satellite at a time and would feature a modular design enabling it to handle lighter Earth observation and scientific satellites as well as commercial telecommunications spacecraft weighing up to 6,000 kilograms.

The French government has announced plans to use a public bond issue to invest 250 million euros in preliminary work on this vehicle, which in principle could be ready for launch in 2025, according to current planning.

In a June 9 interview, ESA Launcher Director Antonio Fabrizi acknowledged that the initial design of Ariane 5 ME raised questions about its performance, price and development schedule.

But he said that is what the review was intended to do. The review, he said, would be completed in July and will be used to steer Ariane 5 ME development in the coming year.

“Our view is that the recurring cost of building the Ariane 5 ME should be no higher than the cost of building the current ECA version of Ariane 5,” Fabrizi said. “Performance is of course a must, but the cost of manufacturing is also an issue, as is the schedule. We are under pressure from our member states to have the vehicle available by around 2016. We’ll see whether we can make this date, but in any event an Ariane 5 ME arrival in 2020 would be too late, in which case we will do something else.”

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