Nasa secretly considered all-female missions to Mars in a report examining sexual dynamics among astronauts, it has been claimed.

The paper showed the space agency had considered enforcing a strict gender divide on potential long-haul missions, according to astronaut Helen Sharman.

Britain’s first person in space told a conference that the rumoured document, filed “some years ago”, was designed to address the “impure thoughts” mixed spacefaring crews might suffer, Mail Online reported.

The document’s age could explain its apparent lack of consideration of same-sex attraction.

Ms Sharman told the New Scientist Live conference: “I did hear some years ago that there was a report. Nasa has never released it, but it was done to see exactly the kind of crew makeup was necessary for the reason we have already alluded to.

“It found that the crew should be the same gender – all men or all women.”

All-female crews would have been better than all-male, the report is said to have concluded, due to women's superior cooperation skills.