PARIS — The head of the German space agency on July 12 said Germany remains unconvinced that the Ariane 6 design decided by the European Space Agency () and enthusiastically endorsed by France is the right way forward for Europe’s launcher sector.
Johann-Dietrich Woerner, chairman of the German Aerospace Center, DLR, said the German government remains in favor of continued development of the current Ariane 5 heavy-lift rocket, with possible evolutions including environmentally acceptable new fuels in place of the vehicle’s current solid-rocket boosters.
Speaking three days after French Research Minister Genevieve Fioraso applauded the solid-fuel design of the next-generation Ariane 6 and the consensus among European governments backing it, Woerner suggested that whatever consensus there may be on Ariane 6 is wafer-thin.
“I am quite certain that after Ariane 5 there will be an Ariane 6,” Woerner said. “But Ariane 5 still has a large potential for improvement, and the question is where the best place is to invest in Europe’s launchers.”
German-French differences about the urgency of developing Ariane 6 — France wants to move quickly, Germany does not — were papered over at last November’s ESA ministerial conference in Naples, Italy, with a compromise that called for preliminary design work on Ariane 6 and continued development of the Ariane 5 upgrade called Midlife Evolution, or ME.
After seven months of work, the 20-nation ESA on July 8 presented what the agency said is the Ariane 6 design that is most likely to be operational by 2021, to cost no more than 70 million euros ($92 million) per launch, and to replace both today’s Ariane 5 and the medium-lift Russian Soyuz rocket that Europe operates from its spaceport in French Guiana.
Antonio Fabrizi, ESA’s launcher director, said in a July 9 interview that the agency concluded that a liquid-fueled Ariane 6 would be more costly to produce per launch than the mainly solid-fueled version the agency decided to pursue.
Two industrial consortia looking at future launcher options concluded that liquid- and solid-fueled Ariane 6 versions would cost about the same if one assumed a launch rate of at least nine or 10 campaigns per year. Any lower launch cadence, he said, would argue for solid propellant.
Woerner did not disagree with that, but said solid propellant carries other disadvantages, including the fact that a solid-fueled second stage adds vibration risks to sensitive satellite payloads and also pollutes the upper atmosphere.
“The solution selected seems to be the most workable in terms of costs, but from an environmental point of view we are really taking a step backward,” Woerner said. “But my main point is: What is this launcher for? Is it to make life easy for commercial satellite operators, or is it to assure European launcher autonomy? If it’s the latter, then there are lots of ways of meeting this objective.”
The Ariane 6 design unveiled by ESA has a payload capability limited to one satellite weighing up to 6,500 kilograms to be launched into geostationary orbit.
Woerner said most studies suggest that satellites, on average, are getting heavier, not lighter, and that a capacity limited to 6,500 kilograms for a launcher to enter service in the 2020s is insufficient. It is also insufficient to carry many Earth escape-orbit payloads that Europe may well need as it works with NASA and others on a space exploration program.
Citing one example, he said, the Ariane 6 design would not be able to carry the NASA-led Orion Multi-Purpose Crew Vehicle whose service module Europe is providing under a barter arrangement with the U.S. space agency.
Any hope that Europe one day would be launching its own astronauts would evaporate with Ariane 6, Woerner said.
Fabrizi said the Ariane 6, while currently designed to launch in a single configuration, has room to grow. For example, he said, the four identical solid-rocket boosters that make up the vehicle’s first and second stages — three comprising the first stage, one as the second stage — could be increased in size to carry heavier payloads.
Jean-Yves Le Gall, president of the French space agency, CNES, said the Ariane 6 design offers the best chance for Europe’s launcher sector to remain competitive in the global commercial market. While the Ariane 6 business model may not need as much commercial business as the current Ariane 5 ECA rocket to be viable, it will need several commercial launches per year to keep per-launch costs down for European governments using the rocket for their civil and military payloads.
“The key to the Ariane 6 DNA lies in having four identical boosters,” Le Gall said in a July 11 interview. “If we’re launching 15 times per year, that’s 60 identical boosters because we have a single design for the vehicle. This is how we can keep costs down.”
Woerner said that for this kind of scale economy to work, all the Ariane 6 solid-fueled boosters would need to be made in the same place. Given today’s European industrial landscape, he said, that would mean in Italy.
But if Italy’s industry is to be given such a large role in Ariane 6’s development, the Italian government will have to agree to pay a corresponding share of Ariane 6’s development costs. Given the French insistence that Ariane 6 be approved for full development starting in 2014, can Italy support such a financial charge? Woerner asked.
In addition to the cost of up to 3.5 billion euros ($4.6 billion) for Ariane 6, European ministers next year will be asked to decide on whether to complete development of the Ariane 5 ME, at a cost of about 1.5 billion euros.
With France tentatively agreeing to fund about 50 percent of each vehicle, that would mean the French government committing, starting next year, to 2.5 billion euros in rocket development payments. Asked whether France could finance both programs, Le Gall said it is too early to determine what will cost how much.
Fabrizi said ESA will finish its preliminary requirements review for Ariane 6 in October, at which point a more detailed cost and performance estimate will be available.
“We are at risk here of the European Space Agency becoming, in effect, a European Launcher Agency,” Woerner said. “We in Germany happen to think there are many things ESA does — environmental observation, the international space station and other things — that should not be sacrificed to launchers at a time when overall space budgets will remain flat.”