Europe's space chief on Monday said the International Space Station faced lean times as a result of the US shuttle phase-out and said project planning for transport to the ISS had been "anarchy".
Jean-Jacques Dordain, director general of the European Space Agency (ESA), said the scheduled phase-out of the US space shuttle meant "we are not in a very comfortable situation, and that's just a euphemism."
"The biggest lesson from the international space station programme is entirely the lack of a joint transportation policy," he said at a press conference on the sidelines of the Paris Air Show.
"The International Space Station is a splendid cooperation between five partners, but they did make a mistake... we didn't discuss things sufficiently," Dordain said.
"Each party made a unilateral decision," Dordain said, admitting though that this approach was "justified on individual grounds."
"NASA made a unilateral decision to stop the shuttle, ESA took the unilateral decision to develop the ATV, Japan took the unilateral decision to develop an HTV. Anarchy," Dordain said.
The ATV (Automated Transfer Vehicle) and the HTV (H-II Transfer Vehicle (HTV) are unmanned supply ships, as is Russia's veteran Progress freighter.
The shuttle has been the key means to take humans and freight to and from the ISS.
Its retirement after its last mission, starting July 8, means that the station will depend entirely on the Russian Soyuz system for transporting astronauts.
The Soyuz cannot take large non-human payloads, such as big experiments or equipment that needs a fix on Earth.
The three other freight systems for the ISS, meanwhile, are all designed to be one-way systems, which means they are sent to Earth to burn up in the atmosphere after separating from the ISS.
This includes Europe's ATV, the second of which, the Johannes Kepler, undocked from the ISS on Monday ahead of a suicide plunge on Tuesday.
Dordain said ESA had no plans to give Europe its own manned flight capability.
Europe has a powerful launcher, the Ariane 5, but in face of the costs of manned space flight has always placed its astronauts on the shuttle or the Soyuz.
Dordain said ESA and NASA were in talks about possibly adapting the ATV for the US agency, which expects a gap of several years between the end of the shuttle and the introduction of a likely rocket-and-capsule system provided by the private sector.
"We are currently discussing with NASA about how we can converge the interests of NASA and the interests of ESA, which are not necessarily the same," he said.
By autumn, he said, ESA hoped to have a convergence of views on a "module," a common blueprint that could be used for NASA but also help to expand the use of the ATV.
"We are working but we are still far from a result," he said.
Explore further: Red moon at night; stargazer's delight