YNOT – If humanity is going to survive for the long haul, meaning thousands of years, at some point we are going to have to leave the Earth behind. As things stand now, we’re trashing the planet, using up non-renewable resources and generally overpopulating the joint at a breathtaking pace.

Heading out into the Great Beyond will not be easy, though.

“The distances to the stars at vast,” Athena Andreadis, a biologist at the University of Massachusetts Medical School, told attendees at the 100-Year Starship Symposium in Orlando, Fla., recently. “Large starships will have to be self-sustainable. We don’t have such technology yet.”

But that’s hardly the biggest of mankind’s problems with interstellar travel. Instead, scientists at the symposium agreed sex in space presents an enormous set of challenges that must be overcome in order for mankind to survive.

Even though making whoopee in space has been a nerd fantasy for a very long time, the reality is far from alluring.

“Sex is very difficult in zero gravity, apparently, because you have no traction and you keep bumping against the walls,” Andreadis said. “Think about it: You have no friction, you have no resistance.”

Has anyone ever attempted to prove or disprove that hypothesis? The official word from governmental authorities is “no.”

“There is no official or unofficial evidence that there were instances of sexual intercourse or the carrying out of sexual experiments in space,” Valery Gogomolov, deputy director of the Moscow-based Institute of Biomedical Problems, told Space.com earlier this year. “At least, in the history of Russian or Soviet space exploration, this most certainly was not the case.”

Although NASA didn’t weigh in for the U.S., someone with first-hand knowledge of space travel did.

“As for any couple having had sex in space, I seriously doubt it,” former U.S. astronaut Leroy Chiao told Space.com. “Guys are guys. If a guy had sex in space, he would not be able to stand not bragging about it. Sorry to disappoint you, but there it is. We would all know about it. Or, I should say, we will all know about it when it happens.”