A City on Mars: Can We Settle Space, Should We Settle Space, and Have We Really Thought This Through?

In one sentence: Biologist Kelly Weinersmith and cartoonist Zach Weinersmith — a married couple — spent four years researching whether humans can actually settle space, and their conclusion is that building a self-sustaining, multi-generational settlement anywhere (Moon, Mars, or orbit) in the near term is far harder than boosters claim.

Overview

The book's organizing question is simple: what does a "successful space settlement" actually require? Kelly Weinersmith spells it out precisely — families genuinely living on the surface of Mars, able to support themselves through careers, and able to have children who themselves grow up and have children. The authors weigh the Moon, Mars, and an orbital space station against each other and land on Mars: "The Moon, Mars, or creating an orbital space station. And among those, Mars is overwhelmingly the best option" — the Moon is too carbon-poor, while Mars has accessible water and is comparatively easier to reach. But most of the book is spent taking that "best option" apart piece by piece: radiation, bone loss, reproduction, food, psychology, governance — each harder than the last.

Why It's Recommended

This book earns its place in the library on sheer weight of evidence: Kelly and Zach Weinersmith appeared on Short Wave twice in their own right, more than six months apart (2024-11-13 and 2025-04-21), walking through the book's arguments point by point — about as solid an "author as guest" credential as this library has. What makes it worth reading is its stance: not anti-space, but anti-hype. The authors deliberately separate "can we" from "should we" — as host Regina Barber puts it, "Can we do it in our lifetimes? And, more importantly, should we?" The picture they paint is unglamorous: shielding from radiation means burying habitats meters underground, not the glossy glass domes of concept art — "So none of those beautiful glass habitats that maybe you've seen in artist renditions. We're living like mole people underground." Protein is unlikely to come from chickens or cows: "you either have to be a vegetarian, or you need to be comfortable with insect as a protein source." And reproduction risk has barely been studied: "I wouldn't want to be the first woman on Mars hoping my hips are going to hold out when labor kicks in."

Yet the Weinersmiths are not pessimists about space itself. Kelly says the research left her loving Earth more, not less: "I really appreciate this planet that we evolved on and we're so well adapted to. I'm staying here." And Zach takes direct aim at treating Earth as expendable: "there is no plan B... he is a fool because Mars is so bad, you could not, for $10 trillion, make Earth as bad as Mars." It's a book that rigorously interrogates the feasibility of space settlement while flatly rejecting the logic that Earth is disposable because Mars is reachable.

Source

Both episodes are hosted by Regina Barber with Kelly and Zach Weinersmith as guests: "Should humans plan to live on Mars? Probably not anytime soon" (2024-11-13) and "Why you probably won't be living on Mars anytime soon" (2025-04-21) — largely overlapping content across the two airings. Both open with Barber's introduction: "she and her partner, Zach Weinersmith, spent four years researching space settlement for a book called City on Mars." (Note: both transcript mirrors give the title as "City on Mars," without the article "A" — inconsistent with the book's official full title. That wording is mirrored verbatim here; the frontmatter title fields use the book's official full title.) Data from the book is cited throughout both interviews, including roughly 1% hip bone loss per month, a Martian atmosphere just 1% as thick as Earth's, and women making up only about 10% of everyone who has ever been to space. Both episodes close on Zach's "no plan B" line.