PARIS — Europe’s Air & Space Academy says the French and European space agencies are moving in the wrong direction on the future Ariane 6 rocket and should delay development in favor of a redesign that provides more growth potential.

The academy is urging the agencies to stop work on the Ariane 6 they approved in November with a view to beginning full development in 2014. The academy-favored rocket would use liquid propulsion instead of solid, and would face four more years of preparatory work before moving to full development in 2018.

In the meantime, the academy says, Europe should focus on an upgraded heavy-lift Ariane 5 that would fly for a decade before both it and the Europeanized version of Russia’s medium-lift Soyuz rocket are replaced by the all-liquid Ariane 6 in 2027. This rocket, called Ariane 5 ME, has been in design for several years. Continued work on it was approved, alongside Ariane 6, at the November meeting of European Space Agency (ESA) governments.

Further modifications of the Ariane 5 ME could be made to assure it is capable of maintaining Europe’s place in the global market to launch commercial telecommunications satellites. The academy suggests that the Ariane 5 ME’s promise of deorbiting its upper stage to remove orbital debris could be suspended, when necessary, to give the vehicle the requisite payload lift capability.

In a May 8 letter sent to ESA Director-General Jean-Jacques Dordain, the academy’s launch vehicle working group — comprised of former ESA directors and European space industry officials — urges ESA to “urgently reopen the configuration studies” for Ariane 6.

The academy specifically alleges that the current Ariane 6 version of two solid-fueled stages topped by a cryogenic upper stage is a dead-end design that does not permit the flexibility needed in a rocket that will serve as Europe’s main launcher for several decades. “It is the wrong choice,” the letter says.

Beyond the engineering debate of solid- versus liquid-fueled rockets — a debate as old as the space age — the academy’s letter and annex of supporting arguments says the current Ariane 6 design cannot win sufficient political support in Europe to assure its long-term success.

“The upheaval of the European launcher industry which would ensue with the development of [the solid-fueled Ariane 6 now being designed] would not be industrially recoverable,” the letter says. “Further, it would be extremely difficult to maintain the European character of such a program and to rally around it broad support from [ESA] member states.”

The academy reasons that the design-to-cost obsession of Ariane 6 promoters will force the program into a corner in which too few European governments will be motivated to support its expected development cost of around 4 billion euros ($5.2 billion).

The backers of the current Ariane 6 design agree that one of the program’s principal challenges, in addition to meeting the goal of a vehicle that can be assembled and launched for 70 million euros, is finding sufficient room for German industry to entice German government financial support.

The friction between France and Germany on the way forward in launch vehicles was papered over at ESA’s November meeting by an agreement to continue work on both Ariane 5 ME and Ariane 6, with a separate budget line devoted to finding synergies between the two vehicles’ upper stages.

Whether both vehicles’ full development can be financed at next year’s ESA conference is unclear. German government officials have said: We support Ariane 5 ME and we will reserve judgment on Ariane 6. French officials say: We are all-in for Ariane 6, and unsure about Ariane 5 ME.

In an annex to its letter to ESA, the academy says a liquid-fueled Ariane 6 would not cost much more than the current solid-fueled Ariane 6 design but would provide more room for growth as the vehicle navigates the launch-services market’s evolution over the next few decades.

The annex notes that launchers in the United States, Russia and China all feature liquid-fueled designs, and that even the solid-fueled Ariane 6 will have trouble meeting the 70 million-euro cost target.

The academy estimates that today’s Ariane 5 ECA rocket costs 145 million euros per launch. The solid-fueled Ariane 6 will likely cost 98 million per launch, at least at the outset. It will be difficult to cut costs to arrive at the announced target.

The liquid-fueled Ariane 6 would also cost 98 million euros per launch, meaning costs should not be a factor in the competing designs. 

“Is it possible to get a 25-30 percent reduction in launch cost?” the academy says. “The 70-million-euro objective is, in any case, difficult to attain … since one cannot expect meaningful technological jumps in the solid boosters’ domain.”

But while it costs little more than the solid-fueled version, the liquid-fueled Ariane 6 could be upgraded with two liquid-fueled strap-on boosters to provide substantially more heft. The academy calls this rocket the Ariane 6 Heavy and it resembles the Delta 4 Heavy.

“The commitment made will cover a very long time, many decades,” the academy says in urging ESA to step back from the current Ariane 6 design. “Any error made will be very costly, for a very long time.”


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Peter B. de Selding was the Paris Bureau Chief for SpaceNews.