Space — the final frontier! Well. For a small part of humankind, at least. Out of the eight billion humans who constitute the extent of our species in the Milky Way, five billion live on Earth, most of the other three on Earth-like worlds, and few of them have any desire to leave their cradle. In total, less than 5% of humanity has embraced the spacer lifestyle, inhabiting stations, spaceships, and underground settlements on moons or planetoids.

Still, four hundred million spacers is a lot of people, and some of these communities have been around for almost two centuries — the oldest off-world settlement is the lunar city of Shackleton crater, which recently celebrated the 175th anniversary of its foundation. How did spacers adapt so well to their new environment? Such was the question journalist Peter Vangelis tasked himself with answering in this pop-science book, as he took a shuttle to the nearest space station, the venerable Nana Buluku Orbital in low Earth orbit.

Instead, he found a wild and somewhat inconvenient truth — spacers did not really adapt. Because space sucks. The list of adverse health effects zero-g and radiation have on the human body takes a good third of the book — because they are quite numerous. Zero-g puts a heavy toll on pretty much every single part of the human body, from the obvious (bone and muscle loss, the face becoming puffier), to the lesser known (spacers have skyrocketing rates of eye diseases due to issues with the pressure in their cornea) and the frankly arcane (the gut microbiome really doesn't enjoy the absence of gravity, and it turns out neurons don't either). Radiation exposure especially doesn't only increase the rates of tumours, but it also has cascading impacts on every part of the human body. And treating wounds? Oh, yes, blood doesn't flow outside the wounds, it has to be mechanically pumped out. And anaesthesia doesn't work as well as it should, or in some cases, doesn't work whatsoever.

Space really sucks. The whole universe wants you dead. So what did we do about it?

Not much, in the grand scheme of things, and it's not by lack of trying — just about all medical techniques, with the notable exception of full genetic engineering (the voluntary creation of human subspecies remains a touchy and complex political topic) have been mobilised to try to solve the plight of spacers. With the hindsight of two centuries of continued space presence, modern technology has managed to mitigate the most grievous impacts somewhat. After all, most spacers live long and fulfilling lives, their life expectancy in good health is only slightly below average (115 years instead of 121 for the terrestrial human cohort) and, odd skin colours notwithstanding, they look broadly human. Radiation turned out to be less of a problem than anticipated, and modern treatments are superb at handling cancer, especially in the preventative phase. We can replace eyes. We can fix gut microbiomes. We can put spacers in centrifugal gravity stations so they give birth without complications. We can handle zero-g traumatic injuries with enough training and dedicated equipment. We can, broadly speaking, alleviate the murderous desires of space.

Or can we? What Vangelis discovered in his investigations is that spacers…actually spend quite a lot of time on solid, Earth-like ground! On average, a spacer spends three months a year in the environment of a terrestrial garden world, and those who don't tend to live in massive centrifugal gravity stations that emulate such environments. Spacers who never come back to a planet-like environment, now, that's another issue. Focusing on this cohort paints a much bleaker picture -- because modern medicine can only do so much. It can't repair multiple failing organs at once. It can't rewire neurons. It can't support weakened hearts for a century. Even implants can't do much when they themselves are getting tumours. That's why most deep space travellers either take frequent stops on uninhabited Earth-likes, or are artificial intelligences, unconstrained by human bodies.

We don't live in space, concludes Vangelis, not really. We live alongside it. Because while it's beautiful and full of wonders, it still wants to kill us.

Art made for Starmoth by Garnouille.