20 years ago, Arthur C. Clarke looked ahead to the 50th anniversary of man's landing on the Moon and wrote a "Letter From Clavius" dated July 20th, 2019:

It doesn’t seem like fifty years—but I cannot be sure which memories are false, and which are real.

Present and past are inextricably entangled. The monitor screen has just shown the ceremony at Tranquillity Base, culminating with the third hoisting of the American flag. It was blown down, of course, by the blast of Eagle’s ascent stage, and lay there on the trampled Moon soil for thirty-six years until the Apollo Historical Committee reerected it. Then the big quake of 2009 knocked it down again; this time, we’re assured, it would take a direct hit by a fair-sized meteor to lower it.

Now, immediately after the live transmission from Tranquillity, they’ve put on a grainy old tape—yes, tape, not vidule!—from exactly half a century ago. And there I am back in the CBS Studio on West 57th Street with dear old Walter Cronkite and. wise-cracking Wally Schirra, watching Neil Armstrong take that first step off the ladder.

For the hundredth time, I strain my ears. Neil Armstrong once told me (and by then he must have been heartily fed up with the whole subject), “What I intended to say was: ‘That’s one small step for a man, one giant leap for mankind.’ And that’s what I thought I said."

Sorry, Neil—you fluffed! The “a” got short-circuited between brain and tongue. But it doesn’t matter; this time, at least, history has been correctly reedited.

Fast-forward to the present, and an article titled, "One small word is one giant sigh of relief for Armstrong" in England's Times Online, dated October 2nd:

Mr Armstrong has long insisted that he meant to say “one small step for a man . . .” — which would have been a more meaningful and grammatically correct version, free of tautology. But even the astronaut himself could not be sure.

“Damn, I really did it. I blew the first words on the Moon, didn’t I?” he is reported to have asked officials later, amid uncertainty as to whether he had blown the moment or simply been drowned out by static interference as his words were relayed 250,000 miles back to Earth.

Now, after almost four decades, the spaceman has been vindicated. Using high-tech sound analysis techniques, an Australian computer expert has rediscovered the missing “a” in Mr Armstrong’s famous quote. Peter Shann Ford ran the Nasa recording through sound-editing software and clearly picked up an acoustic wave from the word “a”, finding that Mr Armstrong spoke it at a rate of 35 milliseconds — ten times too fast for it to be audible.

Mr Ford’s findings have been presented to Nasa officials in Washington and to a relieved Mr Armstrong, who issued a statement saying: “I find the technology interesting and useful. I also find his conclusion persuasive.”