US President Barack Obama welcomed the crew of Apollo 11 to the White House on Monday to mark the 40th anniversary of their journey to the moon and called the three men "genuine American heroes."
On July 20, 1969, Neil Armstrong and Buzz Aldrin were the first humans to set foot on the lunar surface, while fellow crew member Michael Collins circled the moon in the command vehicle.
"I think that all of us recall the moment in which mankind finally was untethered from this planet and was able to explore the stars; the moment in which we had one of our own step on the moon and leave that imprint that is there to this day," Obama said.
"And it's because of the heroism, the calm under pressure, the grace with which these three gentlemen operated, but also the entire NASA family that was able to, at great risk oftentimes, and with great danger, was somehow able to lift our sights, not just here in the United States but around the world."
Obama, who has ordered a review of all US manned space flight programmes, said the US would try to "continue the inspirational moments of NASA". The space agency is planning to return to the moon by 2020 in a next generation spacecraft now being developed.
The president recalled watching as a child in Hawaii as the capsules containing Apollo astronauts were fished from the sea and brought back to land.
Monday's 40th anniversary was marked by NASA events with the Apollo astronauts as well as celebrations at the National Air and Space Museum in Washington and a slew of media coverage, including realtime rebroadcasts of the events on the internet.