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.
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.
In the recording of Neil Armstrong's iconic phrase he says: "One small step for man. One giant leap for mankind". However, "man" and "mankind" mean much the same thing in this context.
Explanations offered for the discrepancy are that perhaps transmission static wiped out the "a" or that Commander Armstrong's Ohio accent meant that his "a's" were spoken softly.
In 2006, an analysis by an Australian entrepreneur added credence to these explanations - as it found there was a gap for the "a". However, subsequent analyses disputed this conclusion.