The US space agency National Aeronautics and Space Administration (Nasa) will lose about 3,900 employees under Donald Trump's sweeping effort to trim the federal workforce — at the same time as the president prioritises plans for crewed missions to the Moon and Mars.

With looming budget cuts at NASA, scientists are voicing their fears about the safety of ongoing missions. Echoing the tragic Challenger incident, a collective letter from NASA staff raises alarms over the potential loss of crucial data and the jeopardizing of international collaborations.