Well, it had to come up at some point. With all the recent talk about a possible manned mission to Mars, one topic that hasn't had a lot of discussion is this: If we send colonists to the red planet, will sex in space be a problem?

And just how much fun is it to experience zero-gravity nookie?

Presumably, if we're going to send people to live on another world, they'll want to have sex somewhere in that final frontier.

NASA hasn't said much about the subject, and it raises some questions: Have any astronauts done it already? And do we know if children could be conceived and survive in space?

Does NASA have any concerns about male and female astronauts engaging in sex in space? It's apparently a big concern when considering a manned mission to Mars.Writing in the newly released book "The Human Mission to Mars: Colonizing the Red Planet" (Cosmology Science Publishers), Rhawn Joseph of the Brain Research Laboratory in Northern California considers the sexual possibilities of space travel.

"Humans are sexual beings and it can be predicted that male and female astronauts will engage in sexual relations during a mission to Mars, leading to conflicts and pregnancies and the first baby born on the red planet," Joseph writes.

He even suggests the possibility that male and female travelers to Mars should fly in separate spacecraft.

On the general subject of sex in space, Joseph says that "the sex act during a journey to Mars may require potentially complex sexual gymnastics. On the other hand, any difficulties associated with sexual intercourse in space may turn out to be an easily solved problem of docking and entry as humans are notorious for inventing ways of having sex despite all manner of logistical impediments."

While NASA doesn't have an official policy regarding sex in space, astronauts are expected to adhere to the part of the "Astronaut Code of Professional Responsibility" that requires them to maintain "a constant commitment to honorable behavior."

But under the conditions of a long space journey, will men and women actually behave according to the rules?

"If male and female astronauts share a cramped space ship for years, surrounded by stars blazing in the blackness of night, thoughts are bound to turn to sex and romance," writes Joseph.

A mission to Mars is expected to take about two years, plenty of time for crew members to act on their sexual urges.He references "the well publicized [2007] case of female astronaut Navy Capt. Lisa Nowak and Space Shuttle pilot Cmdr. William Oefelein, who flew together on the space shuttle and engaged in an adulterous relationship which allegedly almost led to the kidnapping and murder of Nowak's rival, Air Force Capt. Colleen Shipman."

It's estimated that a mission to Mars would take almost two years: nine months in either direction and a three-month stay on the Martian surface. And Joseph hints that the emotional bonds created between the astronauts would potentially lead them to act on their sexual urges and would also affect the rest of the crew.

"It can be surmised that all aspects of the mission would be put in jeopardy. Crew mates would unlikely be supportive as their ability to perform their duties or to live comfortably would be impacted."

Sponsored LinksAnd there are also many unanswered questions regarding any radiation effects on both male and female astronauts during the journey and their time on Mars, as well as how healthy any children who are born in such unknown conditions would be.

Should only married couples be chosen for these voyages? There are no guarantees that a couple would stay together, and they may decide to change partners during a two-year mission.

But Joseph considers a lighter, positive side of all of this sex-in-space talk.

"By contrast, once safely on the red planet, sex on Mars and the subsequent birth of the first Martian would truly make humans a two-planet species, and would be the first step to human colonization of the cosmos."