They signed a development contract at the Paris Airshow on Thursday to develop a demonstrator engine, powered by liquid oxygen and methane.

Airbus Safran said it would use new manufacturing techniques, including the use of 3D printers, to keep the engine's cost down to around 1 million euros ($1.1 million).

"The commercial market - at least the European one - is asking for reliability, on-time delivery and cost, and we have to find the best way to answer these market expectations," its CEO, Alain Charmeau, told Reuters.

The firm, a joint venture between Airbus and Safran that will become ArianeGroup on July 1, currently powers the rockets it uses to launch satellites for commercial clients with Vulcain 2 engines costing around 10 million euros each.

Prometheus, whose partners also include Italy's Avio, GKN from Sweden, and Safran AeroBooster from Belgium, demonstrated Europe's commitment to remain a major player in the global "race for access to space", Charmeau said.

As one growth driver for the industry he identified the adoption of technology enabling driverless cars, which would boost demand for communications satellites - and hence for rockets to launch them - to relay uninterrupted signals.

"We know it will happen. We see prototypes that are already working in Germany and California," he said. "We know this will be a big market but when is difficult to predict."

In the near term, ArianeGroup would remain focused on rolling out the successor to its current Ariane 5 rocket.

"We need, and will have Ariane 6 in 2020, but we also have to prepare for the future ...and that is why this (Prometheus) program is important," he said.

The jury was still out on the issue of reusability, however.

California-based Space Exploration Technologies (SpaceX) earlier this year achieved what it called "a huge revolution in spaceflight" by reusing part of one of its Falcon 9 rocket on a subsequent launch.

Charmeau said Prometheus would include work on reusability. "(But) the market is not asking for reusability... As long as we have a limited number of institutional launches it's difficult to bet on reusability."

If the market grew significantly, reusability could become a more important factor, but that was unlikely for 15 years, Charmeau said, adding that ArianeGroup was not competing directly with SpaceX.

He said the group would have estimated sales of 3 billion euros in 2017 and expected flat revenues with a slight upward trend over the next few years, with stronger growth to kick in from 2020.

Avio chief executive Giulio Ranzo told Reuters that reusable engines were not necessarily economically efficient given their need to be refurbished. To cut unit costs, Avio had started standardizing components for different launchers, a solution that was "as efficient as reusable engines".