From Star Trek to Passengers, sex in space has been depicted in science fiction blockbusters for years.

And while NASA categorically insists that 'no humans have had sex in space', that could soon change with the proliferation of space tourism.

Private space firms including Jeff Bezos' Blue Origin and Richard Branson's Virgin Galactic are now offering civilians the chance to venture into space, albeit for a hefty price.

With this new era of spaceflight, David Cullen, Professor of Bioanalytical Technology at Cranfield University, is calling for urgent research into the consequences of sex in space.

'My colleagues and I believe that space tourism companies haven't adequately prepared for the consequences of people joining what we could call the "Kármán line club",' he wrote in an article for The Conversation.

The Kármán line is a boundary 62 miles above sea level that marks the beginning of space. 

While NASA doesn't explicitly ban sex in space, its astronaut code of conduct calls for 'relationships of trust' and 'professional standards' to be maintained at all times.

The space agency has also banned any married couples from going into space together – although this is mostly due to group dynamics, rather than worries of them having sex.

Despite this, Professor Cullen claims that sex in space will happen within the next decade.

'Considering that space travel is no longer reserved for professional astronauts, the various motivations of space tourists and upcoming spacecraft developments, we concluded that in-space sex will probably happen within the next ten years,' he wrote.

But sex in space won't be straightforward. 

Speaking to MailOnline, Professor Anja Geitmann, Dean of the Department of Plant Sciences at McGill University in Montreal, who has done significant research on sex in space, explained that the main issue would be 'for the partners to try to remain in physical proximity, since one can't rely on gravity to push one partner against the other.'