Last June, after the number of women on board the International Space Station doubled to four, NASA commander Alex Poindexter issued a formal policy: Space sex will not be tolerated. "We are a group of professionals," he said at the time. "Personal relationships are not...an issue...we don't have them and we won't." But even if the astronauts did violate Poindexter's decree, there appears to be little chance that any relations would have resulted in an errant pregnancy.

The reason? Space appears to provide its own sort of contraception in the form of sterilizing proton particles that pass through ineffective shuttle shielding, reports Andy Bloxham at The Telegraph. The findings arrive courtesy of scientists at NASA's Ames Research Center, who found that these particles "would probably sterilise any female embryo conceived in deep space" and also reduce the sperm count in men.

As Bloxham notes, "given that travel to distant planets is likely to take decades, centuries or longer, this could make any mission to colonise other environments a non-starter." Meaning, for instance, that a potential death mission to Mars would have little chance of spawning a colony without better shielding technology.

Of course, this hasn't deterred those who continue to plan a Martian foray. Russians cooped up for over half a year as part of a faux-Mars mission to test psychological endurance for a real mission have just now completed their fake Mars walk. Is this useful? Or merely the most expensive piece of performance art to date?