February 1st 2017 is the second season premiere of The Expanse, a Syfy Channel television thriller set in the 23rd century, when humans have a thriving civilization on Mars. Earth and Mars are not friendly, so a chilling scene during the first season shows how to torture native Martians visiting Earth: simply tie them to a wall, forcing them to stand in Earth-normal gravity. Gravitational pull at the Martian surface is just 38 percent what we feel here (0.38 G), so it has been speculated that a child conceived and born on Mars might not be strong enough to survive here. This is just one of many unknowns related to human reproduction off of the Earth. But people are gearing to settle the Red Planet anyway.
Mars One is a human Mars settlement program that’s somewhat ahead of itself. They have no interplanetary space vehicles, no launch vehicles, no Mars landing or ascent vehicles, no engines, no life support systems, no space suits. They nearly had a reality television show, although the deal did not go through, but they’re selecting astronauts to begin living the Red Planet in the early 2030s. Based in The Netherlands, the Mars One Corporation may be an extreme example of putting the cart before the horse, but other organizations and government space agencies do have technical capability to get people across space, so the question is whether we’re ready for a colony.
If we’re only sending astronauts to explore Mars and come home, we are prepared to handle things from a medical standpoint. By “prepared”, I mean that we know enough about the medical dangers of space radiation, weightlessness, low weight, and other issues of interplanetary travel that we can keep astronauts reasonably safe and maximize their performance compared with non-medical dangers, such as the risk of catastrophic vehicle failure. Space radiation and weightlessness will put astronauts at risk for developing several diseases, but it’s possible to reduce the risk and severity with radiation shielding, exercise, and medications. People who volunteer for space missions understand that the protection is not perfect. They put the medical risk in perspective with the risk of trouble resulting from something going wrong with hardware.
But, everything changes when you consider having Martian children. Experiments with different types of animals and eggs in the weightlessness of low Earth orbit (LEO) suggest that humans may have trouble getting pregnant in that environment. This is because a gravity vector (a definite up and down) enables embryos and fetuses to orient in the mother’s uterus. So far, there has not been much research simulating a gravitational acceleration intermediate between weightlessness and the full “1G” that we feel here on Earth. This means that Mars gravity may be enough for pregnancy, or maybe not. We just don’t know yet, nor do we know how children resulting from successful pregnancies in 0.38 G would grow up. Maybe they’d be strong enough to visit Earth, or maybe not. Should being able to visit Earth be a requirement? That is a matter of opinion.
The radiation of interplanetary space also may be harmful to an embryo/fetus developing in the womb. Mars has no magnetic field and its atmosphere is thin, so a lot of the space radiation gets to the surface and colonists would be living underground. All in all, if we’re going to start a colony on Mars, we have some homework to do when it comes to pregnancy.