Project Hail Mary

by Andy Weir

“Your doctorate is in molecular biology, correct? Don’t most scientists agree that liquid water is necessary for life to evolve?” “They’re wrong!” I crossed my arms. “There’s nothing magical about hydrogen and oxygen! They’re required for Earth life, sure. But another planet could have completely different conditions. All life needs is a chemical reaction that results in copies of the original catalyst. And you don’t need water for that!”

Astrophage can propel itself with light and has absurd energy-storage capability. It’s had God-knows-how-many billion years of evolution to get good at it. Just like a horse is more energy efficient than a truck, Astrophage is more energy efficient than a spaceship.

Just like that, all the kids relaxed. “Thirty years?” Trang laughed. “That’s forever!” “It’s not that long…” I said. But to a bunch of twelve- and thirteen-year-olds, thirty years may as well be a million. “Can I be on Tracy’s team for the rock-sorting assignment?” asked Michael. Thirty years. I looked out at their little faces. In thirty years they’d all be in their early forties. They would bear the brunt of it all. And it wouldn’t be easy. These kids were going to grow up in an idyllic world and be thrown into an apocalyptic nightmare. They were the generation that would experience the Sixth Extinction Event.

Light is a funny thing. Its wavelength defines what it can and can’t interact with. Anything smaller than the wavelength is functionally nonexistent to that photon. That’s why there’s a mesh over the window of a microwave. The holes in the mesh are too small for microwaves to pass through. But visible light, with a much shorter wavelength, can go through freely. So you get to watch your food cook without melting your face off.

I sat back down, pulled out my phone, and launched the calculator app. “This would take, like…a lot of energy. Like, more energy than the world has. It would be around ten to the twenty-third Joules. The largest nuclear reactor on Earth makes about eight gigawatts. It would take that reactor two million years to create that much energy.”