Neil Armstrong missed out an "a" and did not say "one small step for a man" when he set foot on the Moon in 1969, a linguistic analysis has confirmed.
The researchers show for the first time that he intended to say "a man" and that the "a" may have been lost because he was under pressure.
They say that although the phrase was not strictly correct, it was poetic.
And in its rhythm and the symmetry of its delivery, it perfectly captured the mood of an epic moment in history.
There is also new evidence that his inspirational first words were spoken completely spontaneously - rather than being pre-scripted for him by Nasa or by the White House.