The ESA needs to grow "its resilience and autonomy, for its own good", ESA chief Josef Aschbacher, told journalists.

That requires bolstering links with other partners, he said, citing Canada, India and Japan.

The announcement, made after a meeting of the ESA's board, came as NASA faces drastic budget cuts under US President Donald Trump's administration.

The cost-cutting measures, which have to be approved by US lawmakers later this year, would hit NASA projects involving the ESA.

Those include the development of an Orion moon capsule, building a Gateway space station orbiting the moon, and the return to Earth of Mars rock samples.

Aschbacher said the scope of the NASA budget cuts was still being studied, but ESA's member countries were already working out how to proceed.