The United States space agency Nasa will lose about 3,900 employees under President Donald Trump’s sweeping effort to trim the federal workforce, at the same time as he prioritises plans for crewed missions to the Moon and Mars.

In an emailed statement, Nasa said around 3,000 employees took part in the second round of its deferred resignation programme, which closed late on Friday.

Combined with the 870 who joined the first round and regular staff departures, the agency’s civil servant workforce is set to drop from more than 18,000 before Trump took office in January to roughly 14,000 — a decrease of more than 20 per cent.

Those leaving Nasa on the deferred resignation programme will be placed on administrative leave until an agreed departure date. An agency spokesperson said the figures could shift slightly in the coming weeks.

“Safety remains a top priority for our agency as we balance the need to become a more streamlined and more efficient organisation and work to ensure we remain fully capable of pursuing a golden era of exploration and innovation, including to the Moon and Mars,” the agency said.

Earlier this year, the Trump administration’s proposed Nasa budget put a return to the Moon and a journey to Mars front and centre, slashing science and climate programmes.

The White House says it wants to focus on “beating China back to the Moon and putting the first human on Mars”.

China is aiming for its first crewed lunar landing by 2030, while the US programme, called Artemis, has faced repeated delays.

Nasa is still run by an acting administrator after the administration’s initial pick to lead the agency, tech billionaire Jared Isaacman — endorsed by former Trump adviser Elon Musk — was ultimately rejected by the Republican president.