The Science of Generation Ships: Could We Actually Do It?

Under one of my other pen names, I’ve written an entire series set aboard a generation ship on a thousand-year voyage to the Coalsack area of space. So I’ve spent a lot of time thinking about what it would take to actually pull something like that off.

Short answer? It’s not looking good. Not yet.

The idea of generation ships has been a science fiction staple for decades. It’s irresistible: a giant spacecraft full of people who are born, live, and die aboard a ship that never lands—where their descendants (hopefully) reach a far-off destination centuries later.

But how close are we, really, to building one?

We’re Still Dreaming Big

Back in the day, stories like Brian Aldiss’s Non-Stop (1958) showed us how things could go completely sideways. The crew forgets they’re on a ship at all, society degrades into something tribal, and rediscovery of their situation is the whole story arc.

Fast-forward a few decades, and Kim Stanley Robinson’s Aurora (2015) hits us with some cold reality. Ecological collapse, microbiome instability, psychological strain—it paints a very believable picture of how generation ships might fall apart before they get anywhere. Not exactly a glowing recommendation.

Other recent takes—like An Unkindness of Ghosts by Rivers Solomon and Braking Day by Adam Oyebanji—lean into the social and cultural messiness that would inevitably evolve in a ship-bound society. Humans don’t stop being human just because you seal them inside a tin can and point them at the stars.

And they’re not wrong.

So… Could We Do It?

Let’s break it down.

1. We Need Gravity. Badly.

This is the big one. We have decades of data now from astronauts, and the news isn’t great. Long-term exposure to microgravity messes with basically every system in the human body—muscles waste away, bones lose density, and your cardiovascular system gets lazy.

And then there are the weird little details you never think about until you read astronaut diaries: the tops of your feet grow calluses from hooking under foot straps all the time, and the soles of your feet go baby-soft. It’s disorienting, physically and mentally.

So, if we’re going to send generations of people into deep space, we need artificial gravity. The current best idea is to spin part of the ship to create centrifugal force—but that brings a whole mess of engineering challenges, especially on a structure big enough to house multiple generations of people, ecosystems, and infrastructure.

Still doable. But hard.

2. Closed Ecosystems Are Tricky Beasts

A generation ship can’t rely on supply runs. Everything—air, water, food, waste—has to be endlessly recycled. We’re starting to get a handle on this (the ISS uses some of this tech already), but scaling it up to support hundreds or thousands of people for centuries? That’s a big ask.

We’d essentially need a fully functioning biosphere in a can. With backups. And backup-backups. And people trained to maintain it for their entire lives, and then train their kids to do the same.

No pressure.

3. Humans Are… Complicated

Even if we solve the engineering problems, we’re still left with the social ones. How do you maintain a healthy, stable society when no one on the ship will ever see Earth—or their destination?

Cultural drift is real. Factions will form. Beliefs will evolve. People will want to rewrite the rules. And if things go sideways, there’s no help coming.

Robinson’s Aurora really leans into this—how stress fractures in a closed society, over centuries, become unavoidable. You can’t pause and reset. It just keeps going… or it doesn’t.

The Fiction vs. the Science

I love generation ship stories for the same reason I love writing them: they force us to think long-term. Really long-term. Not just how to survive, but how to keep civilization going in the face of isolation, entropy, and human nature itself.

In fiction, you get to imagine a crew that pulls it off. Or, sometimes, one that crashes and burns in spectacular fashion. Either way, it makes for a great story.

In real life? We’re still at the theory-and-whiteboards stage.

Will We Ever Do It?

Maybe. But it’ll take a massive leap—not just technologically, but culturally. We’d have to be okay with sending people into the void knowing they’ll never see the end of the journey. That’s a tough sell, no matter how inspiring the mission.

Until then, generation ships are our mirror: a way to explore who we are when everything familiar is stripped away, and all we have left is ourselves, a metal hull, and the stars ahead.

What about you? Got a favourite generation ship story that blew your mind (or broke your heart)? I’d love to hear about it. Drop the title—and the author if you remember—in the comments. I’m always on the lookout for more takes on life between the stars.