"NASA has briefed ESA about the Budget Request, and while some questions still remain about the full repercussions, follow-up meetings are already taking place with NASA."

The European Space Agency said on Monday it was studying the impact of U.S. budget proposals that include cuts to NASA moon programmes in which it has a role, and said it remained open to cooperation with the U.

The International Space Station is facing a $1 billion budget shortfall – separate from President Donald Trump's plans to further cut funding – that will require dropping the number of NASA astronauts on the orbiting platform.