How a Scientist and Cartoonist Envision Living on the Moon and Mars

By the 2030s, if NASA’s and other space agencies’ plans come to fruition, astronauts and the occasional tourist group will frequently visit the moon. Not long after that, they’ll be able to live for extended periods on lunar outposts, much like astronauts do in space stations today. By the 2040s or 2050s, travelers to Mars could become common too.

But what will life actually look like for these intrepid space explorers? (Or foolish guinea pigs, depending on your perspective.) Kelly and Zach Weinersmith envision the future of space settlements in A City on Mars, their new book published Tuesday. The married duo dive into details and practical challenges, including water and food supplies, maintaining people’s health, competition for the most desirable territory, raising kids, and even legal troubles in space. They imagine spats over real estate and labor rights, for example.

Kelly Weinersmith is an ecologist and adjunct professor at Rice University, and Zach Weinersmith is the illustrator of the Saturday Morning Breakfast Cereal webcomic. Together, they previously wrote Soonish about emerging technologies. Now they bring their science communication and cartooning skills to bear on space colonization issues, while also debunking misconceptions about what living in a Martian civilization might be like.

For example, the duo critiques boastful claims by the head of NASA and commercial space CEOs about a profitable lunar economy and Gold Rush-like race for water. “There’s just not that much water. It’s hard to get, and it’s in a tiny number of places. We did a rough estimate of the total area of water, and it’s about the size of a modest gentleman’s farm,” Zach Weinersmith says.

While he likes to make jokes with his artwork, he aimed for more than that throughout this book. “The illustrations are there not just for zingers; they’re there to respond to the text and to provide illumination,” he says.

Throughout their book, the Weinersmiths lay out the pros and cons of building and living on the moon, Mars, and in free-floating space structures—with a clarity that’s often lacking in the bold speeches and comments by space colonization advocates like SpaceX founder Elon Musk and Blue Origin founder Jeff Bezos. The Weinersmiths point out that during long lunar nights the moon’s more frigid than Antarctica. It’s also airless, low-gravity, and bombarded with space radiation, and it lacks carbon for growing plants and any valuable minerals.

Mars comes with many of those challenges and more: The dead Martian dirt is filled with poisonous perchlorate, its dust storms are prone to covering outdoor equipment, including much-needed solar panels, and it’s much farther away, which creates a 20-minute time delay when trying to talk to anybody back home. “So that’s Mars. Most of the problems of the Moon, plus toxic dust storms and half-year flight each way. Why then do so many settlement advocates favor it as the ideal second home for humanity?” the couple writes.

Would-be space settlers will need to be well aware of these obstacles before attempting to set up camp. For example, a year or two of exposure to space radiation, or high-energy particles from the sun and galactic cosmic rays, could threaten astronauts with cancer. While someone might one day design geodesic-dome-like habitats that offer sufficient shielding, for now, the couple writes, it might make more sense to build underground. Living in a windowless basement might not be fun, but it might be necessary for the first generation of space visitors.

While the moon’s pretty big, there aren’t that many prime aboveground spots to set up a base. The Weinersmiths propose another option: lava tubes. “The moon has premium real estate, these extravagantly amazing lava tubes that we’ve never looked inside,” Zach Weinersmith says.

More than 3 billion years ago, rivers of lava flowed on the moon. Sometimes a crust formed, cooled, and solidified above them, creating large underground caves. Mars appears to have similar caverns available too. The couple sees them as places that could be further explored and eventually built inside.

So far, all astronauts have been adults, which means that space agencies lack an understanding of how space could affect kids. Those effects could include not only exposure to radiation, but also to growing up in low gravity and in a place where it’s hard to exercise.

Because there’s such extremely limited information about how space could affect childbirth and harm child development, the Weinersmiths express skepticism about moving civilization to space, at least in the near future. “The science about procreation in space is so unsystematic and basically nonexistent,” Zach Weinersmith says, that any attempts in the next decades to create mass settlements “would essentially be experimentation on children. It would be so obviously unethical.”

Few rules govern what astronauts and tourists can do in space. The Outer Space Treaty—which was hammered out in 1967, before anyone even set foot on the moon—says no one can deploy nukes or claim territory for their own. But negotiators let the next generation worry about the details. If they really wanted to, the couple writes, the first batch of 21st-century lunar explorers, who will likely come from NASA and its partners, could use the limited ice to build a huge sculpture or could melt the regolith to pave the surface into a parking lot—and it would all be legal. The US would only have to provide a consultation beforehand.

There isn’t a precedent for how world powers or commercial entities could protect the environment or share equitably with others. Like low Earth orbit or international waters, the moon is a place where international law imposes few restrictions. “In all this time, there has never been an attempt to treat Moon rocks as unpossessable or as special property that humans must share,” the duo writes. An effort to establish a Moon Treaty in 1979 never really got off the ground.

During the Trump administration, US officials developed a document known as the Artemis Accords, rules for exploration of the moon, Mars, comets, and asteroids. But they’re not binding, and so far only 31 nations have signed on. Those guidelines allow NASA and other future lunar explorers to define safety zones around equipment and facilities. That could mean demarcating a space around a favorite ice patch or crater, and taking ownership over resources like water and minerals. One could even plant a flag, like Buzz Aldrin and Neil Armstrong did on the Sea of Tranquility—although that would be symbolic, since these rules still won’t allow anyone to claim ownership of territory.

Still, given the first-come, first-served nature of these “safety zones,” within 10 or 20 years space powers could be scrambling for the best ice-filled craters and the few permanently lit spots that are most suited for harvesting solar power. “My worry is you get a situation where, say, the US and China, and maybe India—where rival powers with nuclear weapons are fighting over scraps of the moon, sort of pointlessly. Turf wars are scary. I think that’s ominous,” Zach Weinersmith says.

The authors also point out the need for explorers to follow space-related rules on Earth. Right now, for example, SpaceX’s Starship remains grounded by the Federal Aviation Administration following a test flight explosion in April. The agency and the US Fish and Wildlife Service are conducting an environmental review of the launch site thanks to concerns about explosion debris and the “rock tornado” the launch caused. “There are rules and they obviously have effects, despite pro-settlement people who want to ignore them or try to find loopholes or hope they’ll go away. But it matters so deeply for any kind of fantasy about Mars colonization,” Zach Weinersmith says.