It is not widely known that the Apollo 11 television broadcast from the moon was a high-quality transmission, far sharper than the blurry version relayed instantly to the world on that July day in 1969. Among those battling to unscramble the mystery is John Sarkissian, a CSIRO scientist stationed at Parkes for a decade. "We are working on the assumption they still exist," Mr Sarkissian told the Herald.

"Your guess is a good as mine as to where they are." Mr Sarkissian began researching the role of Parkes in Apollo 11's mission in 1997, before the movie The Dish was made. However, when he later contacted NASA colleagues to ask about the tapes, they could not be found. "People may have thought 'we have tapes of the moon walk, we don't need these'," said the scientist who hopes a new, intensive hunt will locate them.

If they can be found, he proposes making digitalised copies to treat the world to a very different view of history. But the searchers may be running out of time. The only known equipment on which the original analogue tapes can be decoded is at a Goddard centre set to close in October, raising fears that even if they are found before they deteriorate, copying them may be impossible.

"We want the public to see it the way the moon walk was meant to be seen," Mr Sarkissian said. "There will only ever be one first moon walk." Originally stored at Goddard, the tapes were moved in 1970 to the US National Archives. No one knows why, but in 1984 about 700 boxes of space flight tapes there were returned to Goddard.

"We have the documents to say they were withdrawn, but no one knows exactly where they went," Mr Sarkissian said. Many people involved had retired or died.

Also among tapes feared missing are the original recordings of the other five Apollo moon landings. The format used by the original pictures beamed from the moon was not compatible with commercial technology used by television networks. So the images received at Parkes, and at tracking stations near Canberra and in California, were played on screens mounted in front of conventional television cameras. "The quality of what you saw on TV at home was substantially degraded" in the process, Mr Sarkissian said, creating the ghostly images of Armstrong and Aldrin that strained the eyes of hundreds of millions of people watching around the world. Even Polaroid photographs of the screen that showed the original images received by Parkes are significantly sharper than what the public saw. While the technique looks primitive today, Mr Sarkissian said it was the best solution that 1969 technology offered.

Among the few who saw the original high-quality broadcast was David Cooke, a Parkes control room engineer in 1969. "I can still see the screen," Mr Cook, 74, said. "I was amazed, the quality was fairly good."