IT WAS one of the most watched moments in television history, with more than half a billion people glued to their sets as Neil Armstrong took the first steps on the Moon on 20 July, 1969.
But now, in the scientific equivalent of recording a soap opera over the prized video of a daughter's wedding day, Nasa admits it probably erased its only high-resolution images of the first moonwalk to make room for data from a satellite.
It leaves the snowy, ghosting images of Armstrong's "giant leap for mankind" as all that remain from the mission, although the space agency has digitally remastered the footage into new "broadcast-quality" pictures released yesterday.
"The inescapable conclusion is that the recordings are no longer," said Dick Nafzger, one of the last Apollo-era video engineers still working for the US space agency at Maryland's Goddard Space Flight Centre.
"The question is why didn't someone see these tapes as something special and keep them. Boy, do we wish they'd done that. Of course, we should have had a historian running around saying, 'I don't care if you want to use them for something else, we have got to keep them'.
"But I don't think anyone in the Nasa organisation did anything wrong. It slipped through the cracks, and nobody's happy about it." Mr Nafzger's findings follow an exhaustive four-year search through tens of thousands of boxes stored in dusty basements for 45 so-called "lost tapes" from the Apollo XI mission.
Nasa believed they might contain electronic information that was linked from the Moon to a radio telescope in Australia which could be converted into much sharper pictures than those broadcast on the day.
The grainy images the world saw in 1969 came from a TV camera pointed at a giant wall monitor at mission control of a live feed, from pictures sent by satellite from Australia to California and on by land-line to Houston – effectively a copy of a copy.
Now, agency officials have concluded that the missing electronic data was inadvertently erased. Hundreds of thousands of boxes of magnetic tapes were recycled in the 1970s and 1980s as Nasa struggled to record electronic output from a burgeoning number of satellites.
"I don't believe that the tapes exist today at all," said Stan Lebar, the designer of the original lunar camera used by Armstrong. "It was a hard thing to accept. But there was overwhelming evidence that led us to believe that they just don't exist any more. And you have to accept reality."
Mr Nafzger said the newly restored footage is an ample consolation. It shows more clearly Armstrong's climb down the ladder from the Eagle lunar module and first step on to the lunar surface, plus several scenes of Armstrong and fellow moonwalker Buzz Aldrin on the Moon.
Neil Armstrong and Buzz Aldrin raise the American flag on the moon. The video compares existing footage with the partially restored video. The thumbnail image shows the new footage on the left and the old on the right.