Perhaps the most crucial and understudied is how human reproduction would happen in space. There are good reasons to believe it will be difficult, dangerous or potentially impossible. But the data is so limited, and there are too few resources being spent to study it. This is ominous, given that some private space-launch companies, including SpaceX, have an explicit goal of creating civilizations off Earth. These visions are used to attract huge amounts of money and talent, helping to make the space economy worth an anticipated $1 trillion by 2030, and encouraging a new space race with China to build permanent bases on the moon and Mars. And yet without the sure knowledge that humans can be born and develop in these places, any such goal should be considered a fantasy at best, ethically perilous at worst.
Astronauts have confirmed over the past few decades that in space, the flesh is willing. But truth be told, we don’t even know if you can actually do the fun part of making space kids. While the moon and Mars provide some gravity, a vast majority of data on space physiology comes from orbital space stations, where astronauts hang in constant free fall. Weightlessness is ideal for physics problems but not for intercourse; a nudge toward you will send you flying backward with equal and opposite momentum. Without the familiar frame of reference provided by Earth’s gravity, concepts like “top” and “bottom” are without physical meaning. All of this will make the orientationless mambo awkward. The space popularizers James and Alcestis Oberg wrote in 1986 that those who attempt the act “may thrash around helplessly like beached flounders until they meet up with a wall they can smash into.”
Assuming this is undesirable, you’ll want something that keeps people together. The engineer and futurist Thomas Heppenheimer called for an “unchastity belt.” Another concept, pitched by Samuel Coniglio, a former vice president of the Space Tourism Society, is the “snuggle tunnel.” There’s also Vanna Bonta’s 2suit, which would keep a weightless couple connected via Velcro straps.
But what happens after the unchastity belt is unbuckled, the snuggle tunnel sheepishly exited? If the goal is a self-sustaining settlement, it’s important for the encounter to be productive, leading to children, conceived and born on site.
Is this possible? Science can’t answer that yet, but there are plenty of reasons to worry.
The longest consecutive stay in space has been 437 days, and only a few astronauts have gone up for more than 300 days in a row. Bone and muscle loss are commonly observed problems for astronauts. Spacefarers on prolonged missions lose nearly 1 percent of bone mineral density from their lower limbs per month. Bone loss may be less of a problem on Mars, which has 40 percent of Earth’s gravity. But we still don’t know what the effects would be for women planning to give birth or on developing babies, children and adolescents.