Theoretical Model Proposes Converting Asteroids Into Spinning Space Cities

Rochester researchers imagine covering an asteroid in a flexible, mesh bag made of ultralight and high-strength carbon nanofibers as the key to creating human cities in space (University of Rochester illustration/Michael Osadciw)

Rochester researchers imagine covering an asteroid in a flexible, mesh bag made of ultralight and high-strength carbon nanofibers as the key to creating human cities in space

(University of Rochester illustration/Michael Osadciw)

As a child — long before you learned anything about gravity and centrifugal force — did you ever wonder why living beings weren’t simply being thrown off Earth while spinning at crazy speeds on its axis? If you did, you’ve perhaps solved that little puzzle by now.

So here’s another head-scratcher for you: can humans live on/in a world spinning several times faster than Earth and has no gravity to speak of?

Is your mind wandering towards a centrifuge-like setup working on the principle of centripetal force that has human bodies getting sedimented at the bottom? Let us assure you that the picture isn’t nearly as grotesque.

Scientists have actually given this some thought, and believe that humans can establish colonies on asteroids. What’s more, the physics adds up, too — if only with some minor tweaks.

In a study deemed ‘wildly theoretical’ by the researchers themselves, the team from the University of Rochester has outlined a plan for creating large cities on asteroids.

“Our paper lives on the edge of science and science fiction. 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,” said Adam Frank, one of the authors of the study.

Building elaborate spinning space metropolises

The researchers began working on this project during the pandemic simply to blow off some steam. But to get to the origin of this idea, we need to travel forty years back in time.

In 1972, NASA commissioned physicist Gerard O’Neill to design a space habitat that could allow humans to live in space. What O’Neill and his colleagues created were spinning space metropolises made up of two cylinders rotating in opposite directions. A rod connected the two cylinders at each end. And these cylinders would rotate fast enough to provide artificial gravity on their inner surface, but slow enough that people living in them would not experience motion sickness.

Not only did movie franchises like Star Trek incorporate these ‘O’Neill cylinders’ in their fictional worlds, but business moguls Jeff Bezos and Elon Musk have also referenced these structures in their visions for future space habitats.

Merging fact with fiction

While O’Neill cylinders solved the problem of the lack of gravity in space, there was still the problem of getting the necessary building supplies from Earth to space and the associated costs.

Coming back to the present day, the team at Rochester posed this seemingly crazy question: could asteroids be used to create O’Neill cylinders?

Scientists estimate there about a thousand asteroids larger than one mile across exist in our solar system. This abundance and the layers of rock that could potentially shield us from the Sun’s deadly cosmic radiation are definitely advantageous.

“All those flying mountains whirling around the sun might provide a faster, cheaper, and more effective path to space cities,” Frank said.

Bringing the O’Neill cylinders to life

Despite the obvious advantages of establishing habitats on asteroids, there also seemed to be quite a few drawbacks. The rock making up the asteroids is not strong enough to handle getting even one-third of Earth’s gravity from spinning, and most asteroids aren’t even solid but merely piles of rubble.

So to make space habitats out of these asteroids, the researchers had to figure out how to work with rubble piles. But the illustrious team had an answer to this conundrum as well: a very big and flexible bag.

The plan would entail covering the asteroid in a flexible, mesh bag made of ultralight and high-strength carbon nanofibers — each just a few atoms in diameter. The bag would then envelope and support the entire spinning mass of the asteroid’s rubble and the habitat within, while supporting its own weight as it spins.

So imagine that the asteroid covered in the mesh bag is being spun at high speed to create artificial gravity. The rubble flying away from it would get caught in the bag. And once the bag reached its maximum capacity, the carbon nanofibers would snap taut, catching the expanding rubble. This would eventually produce a thick layer of rubble that might act as a shield against radiation for anyone living inside. The cylinder’s spin would induce artificial gravity on the inner surface.

“Based on our calculations, a 300-meter-diameter asteroid just a few football fields across could be expanded into a cylindrical space habitat with about 22 square miles of living area — that’s roughly the size of Manhattan (or slightly bigger than New Delhi) ,” Frank added.

This line of research is still in its infancy, and we won’t be seeing spinning asteroid cities any time in the near future. However, it is interesting to see how something that seemed fictitious could enter the realm of possibility owing to the gigantic technological leaps humanity has made in the last few decades.

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