The US Congress on Wednesday will award the nation's highest civilian honor, the Congressional Gold Medal, to four American astronauts, including the first man to walk on the Moon, Neil Armstrong.

Other recipients are Buzz Aldrin, who was second man to walk on the Moon; and Michael Collins, who was the command module pilot for Apollo 11, the first manned mission to the Moon in 1969.

The fourth winner is former senator John Glenn, the first American to orbit the Earth in 1962.

They were given the nod by Congress in 2009 to receive the award, on what was then the 40th anniversary of the pioneering US mission to the Moon.

The ceremony is set for 11:00 am (1600 GMT) at the US Capitol Rotunda.

Past winners of the Congressional Gold Medal, described as the "highest expression of national appreciation for distinguished achievements and contributions," include Myanmar pro-democracy icon Aung San Suu Kyi, the Dalai Lama, Walt Disney and Pope John Paul II.

Armstrong was on Capitol Hill in September, when he told lawmakers that the end of the space shuttle era has left the American human spaceflight program in an "embarrassing" state and urged US space agency NASA to return to the Moon.