It’s a little more difficult in space...
If we’re going to successfully leave Earth, we’ll need to figure out how to conceive in space. One potential hurdle is the effects of weightlessness on sperm – something that’s currently being investigated by NASA.
In April this year, the Micro-11 project sent human sperm to the ISS for the first time. Researchers are still awaiting the results, but previous work from the same team has shown that bull and sea urchin sperm fare pretty well in space. The bull sperm move faster in microgravity (a trait that’s generally associated with higher fertility), while, in sea urchin sperm, the chemicals that get the sperm cells to start swimming also kick in faster.
“Given what we know from the previous data, our hypothesis is that [human] sperm are going to be found to swim faster in microgravity,” says Dr Joseph Tash at the University of Kansas, leader of the Micro-11 project. If this does happen, he hopes the project will be able to figure out why.
But sperm is only half of the equation. Previous experiments on Space Shuttle missions with female mice suggest that microgravity delays the release of mature eggs from ovaries. Tash has got another experiment in the works to test whether this is a long-term effect – if it is, it’ll be another bridge we need to cross.
Another obstacle to making space babies might be high-energy cosmic rays and the charged particles streaming from the Sun. While radiation levels on the ISS are 10 times higher than on Earth’s surface, they’re nothing compared to levels outside the protection of Earth’s magnetic field, which acts as a deflective shield. Radiation can stop sperm and eggs from being produced, and can also cause mutations, leading to damaged foetuses. We’ll need to find ways to shield space travellers from these effects with radiation-proof habitats, or medicines that can help repair DNA damage.
Once we’ve got over these biological hurdles, we’ll also need to make sure that we send enough people to our new home to keep the gene pool healthy and avoid inbreeding. One hypothetical plan for a 6,300-year trip to nearby exoplanet Proxima Centauri b estimates as few as 98 people would be enough to prevent inbreeding. Others think a crew on the order of thousands is a better bet for such a long mission, to cope with the possibility of a catastrophic event and keep the crew as healthy as possible.
“IN APRIL THIS YEAR, THE MICRO-11 PROJECT SENT HUMAN SPERM TO THE ISS FOR THE FIRST TIME”
Any children born in space will grow up in a very different world from our own Kelly Oakes is a science writer based in London.Colin Stuart is an astronomy author. His latest book, How To Live In Space, is out on 4 October (Andre Deutsch, £16.99).