The US shuttle is the only vehicle that can carry large equipment to the International Space Station and its grounding has left the European Space Agency wondering how else it might send the Columbus research centre into orbit.
"What we hope is for the Columbus to be launched as quickly as possible," Jean-Jacques Dordain, director general of the European Space Agency, told a news conference on Monday.
US space agency Nasa halted shuttle flights for more than two years after the space shuttle Columbia disintegrated over Texas in February 2003, killing seven astronauts.
It launched the Discovery shuttle last July but the fleet was quickly grounded again because of new problems.
The next shuttle flight is tentatively scheduled for May. But Dordain said there are other countries with scientific projects waiting to catch a ride.
"There are others in the queue, notably the Japanese who want their laboratory launched as quickly as possible," he said.
The shuttle has been grounded
at least until May
He also wants to make sure that there will be enough flights for scientists to access the European laboratory after it has been sent into orbit.
"We are trying to avoid a situation where we can launch Columbus but not use it," he said.
The problem has Dordain looking for alternatives. He said he is still keen to work with Nasa but says in future there must be two transport systems in case one breaks down.
No European shuttle
"If there is one lesson we have learnt from the space station, it's that it should not depend on one launcher," he said.
He said there is no way that Europe will be able to build its own shuttle in the foreseeable future.
Russia's Soyuz rockets are the
only link to the space station
Budget constraints and a focus on science projects that could bring more practical benefits to Europeans mean that building a space transport system for goods or people is not a priority.
One possibility is to contribute to a Russian project to develop its reusable Clipper shuttle that might be ready for test flights early next decade.
It would then gradually take over from the Soyuz spaceship, which has been putting cosmonauts in orbit since the 1960s and has been the primary carrier of supplies to the ISS since the shuttle disaster.