Steve NelsonEarth isnt doing so great. Thanks to human-induced climate change, the seas are warming and rising, while the land in many places is alternately choked in drought or inundated with floods. As for us humans, we are engaged in warfare on multiple continents, far-right movements are ascendant across the world and, as of last month, dude wipes are available with a pumpkin spice scent in the United States.Meanwhile, the escape hatch to space is creaking open. Elon Musks company SpaceX has a growing fleet of cheap, reusable rockets. In October, the booster stage for its mega-rocket, Starship, was caught in the grip of a skyscraper-high tower as it descended back to Earth. It was an impressive feat. But Musks goal with these vehicles is even more audacious: to start a self-sustaining million-person city on Mars in the next 30 years.Has anyone really thought this through? Well, yes, as it happens, albeit not Musk. We are a wife-and-husband research team a biologist and cartoonist, respectively and we have spent four years looking into how humans will become space settlers for our latest book, A City on Mars. We set out to write the essential guide to a glorious off-world future. What we learned, however, made us space settlement sceptics.Heres the thing: Mars sucks. When you dig into what life would really look like on the Red Planet, in terms of the squishy details of human existence, it becomes hard to avoid an inconvenient conclusion that moving to Mars to escape Earth would be like moving