A French astronomer's claims that astronauts had sex in space - for research purposes, of course - has prompted Nasa to issue a flat denial.

"We are not, have not, and do not plan to conduct any sex experiments," Nasa spokesman Ed Campion said.

The number of less-than-earth-shattering positions

In his new book, The Final Mission, author Pierre Kohler said that American and Russian astronauts have ventured where no-one has gone before - with the blessing of the space agencies.

Both countries have conducted separate research programmes on the limits of cosmic sex to provide clues on how human beings might survive years in orbit, Mr Kohler said.

"Scientists need to know how far sexual relations are possible without gravity."

The experiments related to future missions planned for married couples on the International Space Station, he said.

Cyberspace documents

Mr Kohler, a respected French scientific writer, cited documents said to have been posted on the internet by a United States researcher on Project STS-XX.


"It appears the so-called missionary position is an easy position only on Earth" - Pierre Kohler

Nasa said the documents were false, and the numbers Mr Kohler cited did not correspond to any numbering system it used.

A spokesman said the "spurious" story was based on internet gossip that dated back a number of years.

The documents allegedly described how scientists drew up a short list of 10 sexual positions to be tested in zero gravity.

Only four positions were possible without the aid of an elasticised belt and an inflatable sleeping bag to keep the pair in close contact.

Blast-off: Did the earth move?

"It appears the classical approach, the so-called missionary position, is an easy position only on Earth, when gravity keeps you pinned down, and that it would be ruled out in space," Mr Kohler said.

Even the successful positions proved to be a struggle - the couple had to rely on sheer muscle power to avoid drifting apart.

"If it was really a joke it wouldn't have been written like this," he said.

The results were videotaped, he said, but were considered so sensitive that the scientists only released censored copies to the space agency.

Taboo topic

Mr Kohler said space agencies always killed speculation on taboo issues.


"We are not, have not, and do not plan to conduct any sex experiments" -Nasa

He remained convinced that the internet information was genuine.

"It's credible. The only problem is that I haven't been able to identify the precise mission."

He had pinpointed all shuttle trips in 1996, but got little further than identifying those with both men and women on board.

The book's publisher, Calmann-Levy, planned to issue The Final Mission on Thursday.