Humans may be living on the moon sooner than we'd thought. Earlier this week, NASA Administrator Jared Isaacman announced an advanced timeline for the agency’s plans to return to the moon and establish a permanent base there. If the plans come to fruition, it will mark a major milestone in manned space exploration. While we already know human beings can live and work in microgravity (with a major assist from technology), what about the next frontier—successfully reproducing? New research published today in Communications Biology is taking aim at that question by investigating how sperm cells function in microgravity.
Researchers from Adelaide University in Australia placed sperm samples from mice and humans into mazes that mimic the female reproductive tract and loaded them into a machine to simulate weightlessness. Known as a 3-D clinostat, this machine features two frames continuously spinning on different axes that keep cell cultures in constant motion to simulate the conditions of space. After several hours spinning in the clinostat, the researchers checked their progress.
So how did the little swimmers do? Not great.
“We observed a significant reduction in the number of sperm that were able to successfully find their way through the chamber maze in microgravity conditions compared to normal gravity,” study author Nicole McPherson said in a statement.
Read more: “Should People Live on the Moon?”
While the microgravity conditions didn’t affect the sperm cells’ ability to swim, it did interfere with their ability to navigate. That said, adding a bit of the sex hormone progesterone, which is released from the egg cell, seemed to boost their sense of direction.
The team also investigated the effects of microgravity on mouse egg cell fertilization, noting a 30 percent reduction after four hours spinning in the clinostat.
“We observed reduced fertilization rates during four-to-six hours of exposure to microgravity,” McPherson said. “Prolonged exposure appeared to be even more detrimental, resulting in development delays and, in some cases, reduced cells that go on to form the fetus in the earliest stages of embryo formation.”
Still, some healthy embryos were able to form, even though they were conceived in microgravity conditions. “This gives us hope that reproducing in space may one day be possible,” McPherson said.
Next, the team plans to investigate other gravitational environments, like those found on the moon and Mars, to find out if the declines in fertilization are gradual or if there’s a threshold effect. We may very well have a permanent base on the moon by then, but the first lunar babies won’t be born for quite some time. 
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Lead image: supplement / Adobe Stock
