Human physiology

Our current knowledge of the health impacts on humans of prolonged exposure to low gravity and cosmic rays remains limited, yet is alarming. Even with astronauts performing mandated exercise and staying for a comparatively short length of time, they often report steep muscle loss and other changes from the low gravity environment, such as lower back pain. The longest any human has spent consecutively in orbit is 437 days (held by Valeri Polyakov), and the longest a human has been in deep space exposed to cosmic radiation without the protection of the Earth's magnetosphere was only 12 days, yet merely one way on a trip to Mars takes six months using current technology. Any trip back would be strictly limited by launch windows for when gravity assists line up, suggesting that even the fastest of Mars jaunts by humans would require spending an exceptionally long time in space. The survivability of such trips, as well as long-term impacts on the human body, are a major question — depending on the kind of Mars settlement, it is possible that "Martians" would be unable to ever safely return to Earth. Blocking radiation is not trivial; incompetently arranged shielding can make radiation even worse, suggesting that only living underground would provide anything like the protection received on Earth from radiation. Astronauts have also reported damage to eyesight, hypothesized to be from radiation.^[5]

Issues often glossed over, but important to a truly long-term human settlement in space, are sex in space, pregnancy, and children. Is it safe or possible to have and raise children in a low-gravity environment such as Mars? It has been suggested that even if it is not, "artificial" gravity could be created, but this leads to its own problems. Hypothetically, a banked racetrack (or "pregnodrome") could be used to constantly accelerate humans downward to Earth-equivalent gravity, but are a mother and child really going to live in some sort of train for 18 years and 9 months? What happens if the vehicle breaks? The problem is even worse for the gravity of the Moon, which is even weaker than Mars.^[6]

Nature of proposed settlements

The Weinersmiths examine what settlements would be like if made. They emphasize that Mars is not a luxurious escape for rich vacationers. Rather, life on Mars would likely be an experience of living underground in tight quarters with little personal space, carefully recycling every drop of carbon including human excrement, eating crickets and drinking beet juice, with mechanical mishaps and failures being potentially deadly. Giant dust storms can cover the entire surface for weeks on Mars. Major questions remain; Martian soil is tainted by perchlorates. Would it be possible to safely grow food with it that would not be similarly tainted? The Moon is even worse, with solely regolith for its surface (equivalent to small shards of glass, far worse than Earth soil), and almost completely lacking in carbon as well as other elements essential to human life such as phosphorus. Finally, giant rotating space stations would at least be able to simulate Earth gravity, but would be completely exposed to radiation, and would require immense amounts of mass to build safely, suggesting a Moon base and a way to build such a structure from mass taken from asteroids or the Moon would be prerequisites to such an endeavor.^[7]

Space psychology also arises as a topic. Current space missions simply use selection to only send the most rock-solid reliable types into space as astronauts, but a major settlement effort would presumably not be able to be as choosy. Would average people be able to adapt to the hardships of space? If someone became irrational, would there be ways to safely restrain them and cover for them? The Weinersmiths examine the closest cases on Earth, involving people cooped up in Antarctica, but even there, rescue and a ride to civilization was possible in the realm of days, rather than months. They also consider the Biosphere 2 experiment, where eight people lived in a tightly controlled ecosystem for a year. While the project lost money, its cost was a tiny fraction compared to the budget of the International Space Station, and suggest that hundreds of similar Biosphere-type experiments could be productively and cheaply run on Earth.^[8]

Sociology, law, and politics

Under the Outer Space Treaty, states cannot be established on the Moon, but acting like a state by occupying territory and taking scarce resources (such as lunar water) is perfectly allowed. Zach Weinersmith's illustrations fill the book, this one of a hypothetical Canadian occupation of a peak of eternal light.

The topic of survival homicide is explored: what would happen if, in the event of an emergency, food and air would better be preserved by killing off some crew members or settlers? And possibly even eating them? Existing precedents such as US v. Holmes and R v Dudley and Stephens are brought up, as well as the likelihood that space settlement would probably proceed under the laws of whichever nation's citizens were sent.^[9] The Weinersmiths also suggest that it is imperative to avoid intentionally creating ethically dubious situations. Space settlement isn't an unplanned disaster like a shipwreck or a mine collapse. If a country was considering sending a group of settlers off to Antarctica, and were warned that if left on their own for a long time they may start treating human life rather cavalierly (e.g. executing the sick, weak, or disabled to conserve scarce resources), the authors say we should not treat that as a cute sociological quirk, but rather a signal that it's not safe to send the settlers yet.

The Outer Space Treaty is discussed, both with what it says and what it doesn't cover (but perhaps should). The OST was written in an era when there were only two major space powers, but the authors consider it in need of an update for the 2020s era of commercial space exploration. Additionally, while the authors are skeptical of the economic case for space (e.g. asteroid mining, hypothetical Helium-3 extraction on the Moon, etc.), if it turns out there really is an economic case for space, they fear it may weaken some of the norms that have kept space exploration peaceful so far, increasing even further the importance of updating global standards on the matter.^[10]

Finally, certain aspects of space settlement suggest that if done with only small populations, the governance style would naturally shift toward authoritarianism, given the strict control of machinery and recycling required for survival. While workers can generally leave an unpleasant company town on Earth at worst, this is substantially dicier on a hypothetical small Mars settlement, where there may be no other place to go, and the bosses control everything about life. This would suggest not making a settlement until ready to "go big" and send a substantial population at once, allowing for redundancy if people quit or die or machines break, given the long travel times to Earth. And while advanced technology is mostly a good thing for space settlement, it still raises its own risks. Powerful future technology to, say, efficiently return material from the Moon to the Earth or perform asteroid mining would also be an extremely potent weapon.^[11]

Conclusions

The authors caution that the difficulties in achieving autarky (that is, true economic self-sufficiency with no need for Earth) remain huge, weakening the case for the first rationale of human survival. Autarky may be distant-to-impossible, requiring millions of thriving settlers or incredibly advanced hypothetical robotics to even consider. The second rationale of "because it's awesome" is only moral if it is also safe. This would likely require biology and ecology research to study and protect humans in space. It would also require aligning spacefaring nations on a new political and legal framework first to avoid the risk of starting World War III in space.^[12]