Nasa’s budget will be cut by 20 per cent, eliminating as a result a major partnership with Europe on Mars exploration, scientists said.

For the White House is proposing a $1.2 billion budget for the US space agency, down from $1.5 billion this year, says Louis Friedman, a former Nasa official.

“It’s certainly dead,” he added, referring to the ExoMars project which aimed to send an orbiter to the Red Planet in 2016 followed by a pair of rovers in 2018, ahead of a possible mission to return samples from Mars to Earth in the 2020s.

According to the deal Nasa and the European Space Agency made in 2009, Nasa would contribute $1.4 billion to the project and ESA would chip in $1.2 billion.

Mr Friedman added that the political will in Europe and the United States was likely strong enough to push efforts towards a new deal of some kind, but the details remain to be seen.

“I don’t think it is hopeless. But there is no indication that Congress is willing to help,” he said.