The denial came in response to a recent story in SPACE.com that reported on a claim John Lewis made in his 1996 book, Mining the Sky, that he went looking for the Saturn 5 blueprints a few years ago and concluded, incredibly, they had been "lost."

Paul Shawcross, from NASA's Office of Inspector General, came to the agency's defense in comments published on CCNet -- a scholarly electronic newsletter covering the threat of asteroids and comets. Shawcross said the Saturn 5 blueprints are held at the Marshall Space Flight Center on microfilm.

"There is no point in even contemplating trying to rebuild the Saturn 5 ... The real problem is the hundreds of thousands of parts that are simply not manufactured any more."

"The Federal Archives in East Point, Georgia, also has 2,900 cubic feet of Saturn documents," he said. "Rocketdyne has in its archives dozens of volumes from its Knowledge Retention Program. This effort was initiated in the late '60s to document every facet of F 1 and J 2 engine production to assist in any future restart."

Shawcross cautioned that rebuilding a Saturn 5 would require more than good blueprints.

"The problem in recreating the Saturn 5 is not finding the drawings, it is finding vendors who can supply mid-1960's vintage hardware," he wrote, "and the fact that the launch pads and vehicle assembly buildings have been converted to space shuttle use, so you have no place to launch from.

"By the time you redesign to accommodate available hardware and re-modify the launch pads, you may as well have started from scratch with a clean sheet design," he wrote.

In years past, rumors have abounded that in the 1970s the White House or Congress had the Saturn 5 plans destroyed "to prevent the technology from falling into the wrong hands".

That seems doubtful -- it would be a formidable terrorist group that decided to build a Saturn 5 to wreak havoc on the world, or build a lunar base. Also, by the1970s, the Soviets apparently had given up on the race to the moon.

Geoffrey Hughes from the Rotary Rocket Company supported Shawcross's view.

"There is no point in even contemplating trying to rebuild the Saturn 5," he said. "Having a complete set of Saturn 5 blueprints would do us no good whatsoever. True, we would still be able to bend the big pieces of metal fairly easily. But they are not the problem.

"The real problem is the hundreds of thousands of other parts, some as apparently insignificant as a bolt or a washer, that are simply not manufactured any more. Everything would have to be redone. So a simple rebuild would be impossible. The only real answer would be to start from scratch and build anew using modern parts and processes. Yet another immense challenge!"

It turns out that NASA is taking on that challenge, but not necessarily to chase asteroids.

Engineers at NASA's Marshall Space Flight Center are working on designs for a new giant launch vehicle called Magnum. It would use a curious mix of Russian rocket engines -- derived from the abandoned Soviet Energia rocket program -- and newly developed strap-on, liquid-fueled boosters that would first be tested out on space shuttles.

The Magnum would use the space shuttle launch facilities at Cape Canaveral and could launch 80 tons (81,280 kilograms) of payload into low Earth orbit (LEO). This compares with around 20 tons (20,320 kilograms) for the piloted space shuttle, and for un-piloted vehicles like the U.S.' Titan 4-B and the European Space Agency's Ariane 5. Its lift capacity, however, would be less than the 100 tons (101,600 kilograms) that the Saturn 5 and Energia could manage.