Bring plenty of leather belts.

That is the advice from astrophysicist and pop scientist Neil DeGrasse Tyson for anyone hoping to have sex in space. Responding to a fan question on National Geographic Channel’s Star Talk, Tyson said you would need the belts to keep cavorting astronauts together.

“Everything is different when you are having sex in a weightless environment,” Tyson said with a smile. “You need things like straps. There are probably some people who are fully equipped with this anyway.”

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Tyson wasn’t so much talking "Fifty Shades Of Grey” as much as explaining the unusual requirements that come with trying to get romantic in an environment where “you are drifting toward  your destination.”

"You begin to see the manifestation of Newton’s Law of motion. You're there floating in space and then you move towards someone and they just sort of bounce off,” he said. “The movement is sort of preserved. There is no friction. So if you want to get together and stay together, you need something to keep you together during all the normal body movements that would characterize having sex in space.”

Related: Sex in Space? Beware the Radiation, Scientists Say

Sex in space has been a sensitive subject for NASA, whose code of conduct for astronauts dictates that "relationships of trust" and "professional standards" are to be maintained at all times. But in all likelihood, colonization would follow exploration and in many cases that would include reproduction.

But a 2011 study in the Journal of Cosmology found that getting pregnant in deep space carries plenty of risks. It found that high-energy particles bombarding the ship would almost certainly sterilize any female fetus conceived in deep space, making it that much more difficult to establish a successful Mars colony once the crew lands.