A top Nasa manager has cast doubt on the space agency’s ability to land astronauts on the moon by 2024.

Kenneth Bowersox, acting associate administrator for human exploration, told a Congressional subcommittee on Wednesday that Nasa is doing its best to meet the White House-imposed deadline.

But he says he would not bet anything on it.

Mr Bowersox — a former space shuttle and space station commander — says it is good for Nasa to have “that aggressive goal”.

He says many things need to come together, like funding and technical challenges, for 2024 to stand a chance.

And he acknowledges there is a lot of risk in making that date.

The Trump administration urged Nasa in March to accelerate its moon-landing plans by four years to 2024.