We could build space cities in asteroids like in sci-fi with this wild concept

Artist's conception of a futuristic city inside an asteroid, nearby a planet.
Artist's conception of a futuristic city inside an asteroid, nearby a planet. (Image credit: University of Rochester illustration / Michael Osadciw)

A pandemic-induced "lockdown" project produced a new vision for how to build cities on asteroids.

The wild asteroid concept would see far-future humans gather up rock rubble in a massive bag made of nanofiber mesh, allowing future astronauts to build a habitat inside the loose asteroid bits as the rocks spin in space.

"This project started as just a way for physicists and engineers to blow off steam, set aside worldly stresses for a while, and imagine something crazy," Ph.D. candidate and study lead author Peter Miklavčič, who is based at the University of Rochester, said in a statement.

The researchers suggest that future Manhattan-sized cities of 22 square miles (57 square kilometers) could be built on these space rocks, just like in science fiction, assuming the base asteroid is at least 1,000 feet (300 meters) across.

Related: Humans could move to this floating asteroid belt colony in the next 15 years, astrophysicist says

"We're taking a science fiction idea that has been very popular recently — in TV shows like Amazon's "The Expanse" — and offering a new path for using an asteroid to build a city in space," added co-author Adam Frank, who teaches physics and astronomy at Rochester, in the same statement.

The study team argues that if their concept indeed works, it would (eventually) allow for lower-cost exploration of the solar system and open up living off-planet to far more people than just billionaires. 

That said, the launch infrastructure is not yet in place for rapid and affordable access to space, let alone any asteroid city-building materials; that may take a few decades at least to build, if not centuries.

The new study borrows from the oft-cited "O'Neill cylinder" concept, first proposed by physicist Gerard O'Neill in a 1972 NASA study. Simply put, the design includes two cylinders that rotate in opposite directions, inspiring billionaires like Blue Origin's Jeff Bezos (who made his fortune with Amazon) or SpaceX's Elon Musk. But past work has suggested that supplying the necessary materials from Earth would be quite costly.

Related: As space billionaires take flight, 'the right stuff' for space travel enters a new era

Miklavčič studies the space rubble that often arises in asteroids, which can in many cases only be loosely held together by gravity. Since a rotating O'Neill cylinder would make such an asteroid fly apart, a flexible bag could be one solution to holding the materials in and allowing a stable base for a city.

The mesh bag would be made out of carbon nanofibers, which are lightweight and yet strong enough to hold together the asteroid rubble in a potential habitat. In theory, a spun-up asteroid inside a bag would fling its rocks into the sides, allowing the bag to expand and hold the rocks tight with the help of the nanofibers. The rubble peppering the bag's side would be held there by artificial gravity and would shield the inhabitants from space radiation. 

While the study is literally 'out there,' the researchers emphasized all the technology is currently in place (albeit at an early stage) and that the science stands up. 

"Obviously, no one will be building asteroid cities anytime soon, but the technologies required to accomplish this kind of engineering don't break any laws of physics," Frank said.

A study based on the research was published in January in Frontiers in Astronomy and Space Sciences, and highlighted by the university in December.

Elizabeth Howell is the co-author of "Why Am I Taller?" (ECW Press, 2022; with Canadian astronaut Dave Williams), a book about space medicine. Follow her on Twitter @howellspace. Follow us on Twitter @Spacedotcom or Facebook.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace

  • Unclear Engineer
    Not seeing the shielding claimed from "space radiation" if the thing looks like the illustration. "Space radiation" comes from all directions, so the big open ends of that spinning tube are tremendous holes in the "shield".

    And, if the asteroid material is so easily displaced that spinning it to 1 G of centrifugal force will make it fly out to the mech tube, then building structures "on top" of it (i.e., at a slghtly smaller radius from the center), and counting on it to support those structures against radial force would seem like building on an unconsolidated rubble pile here on Earth - not acceptably stable.

    And, then there is the need for propellant to accelerate the spin. And of course the need for energy to run systems - so where are the solar collectors and how do you point them at the sun on a rapidly spinning tube - maybe just coat the whole exterior with solar cells?

    Finally, how stable are carbon nanotubes against the space environment? If that mesh tube has a failure, this whole city would have a disaster.
  • ezsimple
    The 1977 report linked in the article addresses these items and is an interesting read.
  • oleg.alexandrov
    The idea of using space rubble is sound, but simply stuffing it in a "carbon fiber sock" is likely not going to produce a reliable structure. The rocks can be heated, pressed, and processed into interlocking bricks for which one can reliably measure their compressive and tensile strength. Will have a higher density as well, so can protect from radiation better. Then, fiber can be spun from basalt and other rock, if needed to tie things together.
  • bolide
    What would be a generic term for this sort of thing? Let’s call it a ‘habifact,’ for ‘habitable artifact.’

    So we’re out there building this thing, and along comes this humongous spaceship. It’s so big it hosts an entire civilization inside. Its denizens have no memory of living anywhere else—just a vague ideal of finding some place to settle down.

    They’re excited to see that we are building our own habifact. But it’s not done yet, so—“Where’s your current habifact?” they ask. “Oh, we don’t have one yet, this is our first. We came from that planet just over there.”

    They are gobsmacked. “You—you have a Planet? An actual planet, that’s nice enough to live on, and allowed you to evolve to this high state, without need of survival technology? Then why in the infinite universe would you want to live out here????”
  • RevKeith
    This might be a viable method to clean up space junk orbiting earth.©2022 lol