Kelly Weinersmith and Zach Weinersmith are a husband-and-wife, New York Times bestselling book-writing duo. Kelly is a behavioral ecologist with a particular interest in parasite manipulation of host behavior and is an adjunct faculty member in the BioSciences Department at Rice University. Zach is the cartoonist behind the popular webcomic Saturday Morning Breakfast Cereal. Both have had their work featured in major publications, such as The Economist, Discovery Magazine, and National Geographic.
Below, co-authors Kelly and Zach share 5 key insights from their new book, A City on Mars: Can We Settle Space, Should We Settle Space, and Have We Really Thought This Through?. Listen to the audio version—read by Kelly—in the Next Big Idea App.
1. Most arguments in favor of space settlement are bad.
There are a lot of aspirational arguments that say we need to go to space soon: to save the environment, to become a wiser species, to end war, to end poverty, or to reinvigorate a wimpy bureaucratized homogenized Earth. The short version is that none of this stuff is likely. The environmental ideas won’t work soon enough to stop climate change and might never be cheaper than things we can do on Earth. There’s no evidence humans become wise, or unified, or peaceful because of space launch. And we’re unlikely to get rich because even fantastic drops in the cost of space launch will cost a fortune to access.
Often, these ideas are based on folk beliefs, not held by actual scholars. The idea that space travel makes you wise largely derives from the writings of a single philosopher, but the empirical evidence is limited and weak. Even the platitudes of astronauts about the view from space aren’t always right. The phrase “you don’t see borders up there” is used often but isn’t even correct. You can see borders between, for example, North and South Korea. Nor would it be wise not to see where light stops and darkness begins.
The environmental arguments might sound more plausible, but they won’t work in this century for climate change. Moving humans and industry to space could conceivably reduce our burden on the planet. But, to keep the population steady at current birth rates, we’d have to move something like 220,000 people to space per day just to keep Earth’s population stable. We currently have no way to get that many people into space and no way to house them. Maybe it’ll work in the 22nd century, but not now.
Unfortunately, aspirational arguments for space settlement are not well-grounded in data.
2. We don’t know enough about how bodies and minds respond to space to settle it safely.
Most of what we know about how bodies and minds respond to space comes from data on astronauts residing aboard space stations orbiting the Earth for short periods. This data is not super useful for understanding how a human would fare spending their whole lives living on Mars, which has more radiation and less gravity than Earth.
Our science from the International Space Station is ominous. Life in microgravity degrades bones, muscles, and eyesight. The 1/6th Earth gravity of the Moon or the 2/5th Earth gravity of Mars may be enough to keep bodies healthy, but we don’t know.
“We have no idea if humans can be conceived, gestated, and born off-world, and we don’t know if those babies can grow up to have babies of their own.”
Also, the data we have may not be applicable to all humans. Astronauts have mostly been male, middle-aged ultra-elites, very few of whom went up for more than half a year, with the record consecutive stay being 437 days. There are animal experiments, too, but they’re short and unsystematic.
This lack of knowledge is especially worrisome when you realize that a successful space settlement will need to allow for human reproduction. We know even less about this than we know about human physiology in space. We have no idea if humans can be conceived, gestated, and born off-world, and we don’t know if those babies can grow up to have babies of their own.
Even if we can get that knowledge ethically, it would take decades and be quite expensive. Without that knowledge, any large-scale space settlement would be experimenting on babies.
3. We don’t know enough about building space habitats to settle Mars.
With current technology, it takes about six months to get to Mars. Once there, you must wait about a year for the launch window to start the six-month trip home. Your equipment had better be reliable!
It’ll always be expensive to ship supplies to Mars, and will (at least initially) be difficult to extract resources from the Red Planet. So you’ll want to be able to recycle as much as you can—everything, including human waste, needs to be incorporated back into a built ecosystem.
How good are we at building recycling systems? On the International Space Station, some water gets recycled, which is why the potable water in orbit is sometimes referred to as “yesterday’s coffee.” That’s pretty much it for space recycling.
Down on Earth, the largest closed-loop ecosystem ever attempted was Biosphere 2 in the 90’s. It was a 3.14-acre facility which housed eight people for two years. They all survived, but they were starving by the time the experiment was over. At one point, they were getting headaches as carbon dioxide levels soared, and oxygen had to get pumped in. They also split into two hateful factions. All subsequent studies have been smaller, and none have attempted to close the loop fully.
So, the best-closed ecology we’ve ever done barely kept eight people alive. Elon Musk wants a million people on Mars in about 25-35 years. But scaling something like Biosphere 2 to a million people would likely require a greenhouse operation the size of Singapore. Even if we somehow deliver that much material to Mars, we do not know how to run such a vast sealed ecosystem because, like with the science of human reproduction, there is little funding.
We need this science if we want a space settlement. The people in Biosphere 2 had to be saved by outside help, which wouldn’t be possible on Mars.
4. A scramble for land or resources in space could create conflict between nuclear powers here on Earth.
Space sucks. A lot. In our solar system neighborhood, the places that suck the least for humans are probably the Moon and Mars. While Mars has a lot more of the stuff that humans need to stay alive, the Moon is closer. So, the Moon is probably where we’re going to go first to test out living in space.
Some parts of the Moon suck less than other parts. At the lunar equator, there’s no water, and nights and days are two Earth-weeks long, meaning you need very robust equipment and batteries or nuclear power to survive the night. But, at the poles, there are small areas where high crater rims catch near perpetual sunlight while also enclosing the only lunar reserves of water in the form of ice. The total area of these special spots is minuscule—something like a few hundred acres.
“What would happen if China and the United States scrambled for the few good parts of the Moon?”
Nations that want permanent Moon bases will want the best spots. But International Law is very unclear about what they can do there. Under the 1967 Outer Space Treaty, nations can’t claim Moon territory, but under the interpretation favored by the U.S. and a number of allies, they could use lunar resources ad libitum. That means lunar water resources are finders-keepers.
What would happen if China and the United States scrambled for the few good parts of the Moon? Some people say this New Space Race has already started. Whereas the first space race was about getting on the Moon first, this second space race is liable to be about something much more conflict-prone: turf. We need a legal system that regulates these claims before fighting starts.
5. Space won’t solve existential risk, but solving existential risk might get us to space.
Given the difficulty of settling space, those who favor it generally come to the table with aspirational goals for humanity. One of the most plausible is that a second human civilization is a backup copy for our species in case we accidentally nuke this one. Or cook it. Or it gets hit by an asteroid. In this vision, space settlement is a Plan B for our species, which makes space settlement a worthy goal regardless of risk or short-term return on investment.
It’s a nice idea, but the danger is that settling Mars may increase the risk to the species—either by sparking a dangerous scramble for turf or simply by requiring a vast infrastructure made of large, heavy, fast-moving objects flying over Earth perpetually controlled by a variety of nations, corporations, and perhaps individual people.
If humanity had some Star Wars force‐field technology, or if war and terrorism were unthinkable, then we wouldn’t have to worry about heavy stuff falling on us from the heavens. But we don’t have this technology and have not moved beyond conflict on Earth. Our ability to harm ourselves vastly outweighs our ability to protect ourselves. As long as that’s the case, settling the solar system will likely increase risks to our species. During the last century, humanity has stacked up a good half‐dozen brand‐new modes of self-annihilation. Do we want to add one more?
This doesn’t have to be a pessimistic vision. If anything, our work convinced us that there’s lots of amazing work to be done in every field, from biology and physics to international relations. We’re not saying we should never settle space. We’re simply saying that going to space will not make us a better species. We must become a better species if we want to go to space.
To listen to the audio version read by co-author Kelly Weinersmith, download the Next Big Idea App today: