‘A City on Mars’ is a reality check for anyone dreaming about life on the Red Planet

That’s the book we pitched, that’s not the book we wrote. The more research we did, the more we felt like settling Mars was way out in the future, not the next couple decades. In fact, if we rushed it, it could be to our detriment because we don’t know enough.

For example, the moon is carbon-poor. Being carbon-based lifeforms, that means we’re going to have to bring a lot of carbon up there if we are going to be making humans and if we are going to be growing plants — all of those things require carbon. The soil on Mars is laden with perchlorates, which is a chemical that binds to your thyroid and messes with all the hormones your thyroid makes. We were like, ‘That doesn’t seem like a great environment to be having kids in.’

And so every chapter ended up being slightly more critical, and then over time, we sort of realized that we were writing about different things. The chapter on how you pick the members to go in the first crew got cut and instead, we ended up adding a couple chapters on international law and how you might actually govern the commons.

But it wasn’t until like three quarters of the way through where our editor was like, ‘Okay, you guys are still trying to make this book sound like space settlements are awesome and coming soon, but you clearly don’t believe that anymore.’

It wasn’t until maybe a year before we were done writing — and we wrote for four years — that we decided this book is actually about why space settlements aren’t coming soon instead of why they are coming in the next decade or two.

But for me, the thing that was the most uncomfortable was thinking about what life would be like if you had babies on Mars. Musk talks about having boots on the ground by 2029 and, two to three decades after that, having a million people there. I think he has said something to the effect of, ‘We don’t need to worry about the reproduction angle. You can just send a million people out there to make it self-sustaining and then we can figure that stuff out later.’

But I can’t imagine a million people being like, ‘We’re just not gonna have sex or babies until this is all figured out and we know it’s safe.’ That’s not how humans function. Between not understanding how we respond to partial gravity and what the kind of radiation you encounter on Mars is likely to do during developments, to having everything figured out so you can get the perchlorates out of the soil before you’re using it to grow your plants, it feels like human experimentation — to be going out to Mars without doing a lot more research.

There are not a lot of books where people want to be wet blankets. And what does get written tends to be written by advocates who are excited about it. It is a beautiful dream to pitch, so I think it’s easier to pitch this as a cool dream than to explain why we need to slow it down. I’m still excited about space settlements but I do think we gotta slow it down a lot.

Most of us specialize. I’m an adjunct faculty at Rice University. I study a very particular kind of parasite and how it manipulates the behavior of fish in particular. So I get that we really narrow down, especially in academia, but the space settlement picture looks scarier when you take a big step back and you look at how all of the different pieces are incomplete right now.

I would love it if everybody who has their own specialty read the book so they could take a broader step back and look at everything. And then I’d love to see us discussing these issues more. I don’t think any of these issues need to stop us from going to Mars. I think they are things we need to work on. Also, I think it is inspiring for the next generation. There’s so many cool questions that need to be answered still and so much cool work to be done in international law, reproduction in space, etc.

You’ll hear, ‘We’re gonna go to the moon and collect helium-3, and helium-3 is going to be awesome.’ Actually, long story short, helium-3 is probably not going to be a great investment in my opinion — we go into it in the book — but anytime you read an article about space settlement, you should realize there’s probably a lot that’s left out. All of these issues are incredibly complicated, and the way that they’re complicated is interesting. So I would love the public to have a more nuanced view of all of the different things that go into space settlement, why it’s complicated and why we can still be excited about it but we shouldn’t rush.

As someone who is in academia, I really like more detailed explanations; I want to know why things work the way they do. Between the two of us, we were able to do four years of research with both of us reading for a couple hours a day, so we were able to amass that knowledge together.

The book starts with biology, so that made it easier for me to get started. At the end of the day, we’re both mega nerds. When it came time to do international law, Zach got the giant textbook on the United Nations Convention on the Law of the Sea and I got the textbooks on the Outer Space Treaty, and we both just read for months at a time until we felt like we understood it.

The Outer Space Treaty is like 2,000 words. It’s so easy to read it and think, ‘Oh, I understand it.’ But once you also read the law, there is a lot of interpretation that goes into it and the history of how it was written impacts how it is interpreted.

I am an ecologist and I’ve helped describe some of the wasp species. There are no wasps on the moon or Mars. At the end of the day, I would never leave Earth; I don’t want to go somewhere where there are no new wasps to discover!

I have always loved Earth, but I appreciate more all the ecosystems it provides us that you just don’t get in a desolate wasteland like the moon or Mars.