After hurtling around the planet for nine months, freeze-dried mouse sperm exposed to the harsh environment of space have successfully produced litters of healthy baby mice, researchers report today.

While not entirely surprising to medical experts, the result is good news for those thinking about whether assisted reproductive technologies could be used to make future space babies if and when humans begin populating worlds beyond this one. (See "Elon Musk: A Million Humans Could Live on Mars By the 2060s.")

Actually having sex in space is a simple Newtonian physics problem that may or may not have already been solved (try getting someone to admit it). The tricky part is that people and animals in space are exposed to both reduced