They propose turning asteroids into space cities with artificial gravity

Astrophysicists from the University of Rochester, USA, are exploring the possibility of using the “rubble heap” of near-Earth asteroids as habitats for human settlements. The idea is based on principles of physics and engineering that theoretically consists of increasing the spin of the dispersing mass of the asteroid’s regolith to generate the artificial gravity of the spin. This revolutionary concept is based on “O’Neill cylinders,” they recently reported.

In 1972, NASA commissioned physicist Gerard O’Neill to create an alien habitat that would allow humans to live in space. O’Neill and his colleagues designed a plan for the rotating capitals of space consisting of two cylinders spinning in opposite directions. The cylinders would rotate fast enough to give artificial gravity on their inner surface, but would be slow enough that people would not experience motion sickness. It was not developed due to technical limitations at the time.

While the O’Neill Cylinders offer a solution to the lack of gravity in space, getting the building materials needed from Earth into space to create them would be difficult and expensive. However, they soon realized there might have been a solution: Could asteroids be used to create O’Neill cylinders?

“All those flying mountains orbiting the sun could provide a faster, cheaper and more efficient route to space cities,” says Adam Frank, professor of physics and astronomy.

Large, solid, rocky asteroids, more than 10 km in diameter, will not have the pulling force to support the required rates of rotation and will therefore break apart. Similarly, asteroids with less mass, which are “cumulus heaps”, have little pulling force and can disperse quickly.

Rochester scientists believe that the use of strong carbon nanofibers would make it possible to contain the regolith mass of the dispersed asteroid in a large, rotating cylindrical bowl, with moderate tensile strength.

The conducted study expands the pool of potential asteroid candidates for habitat, as it may be possible to build habitats from more numerous and smaller bodies, including near-Earth asteroids. According to the researchers’ calculations, the tensile strength required for the container material will increase with the radius and thickness of the habitat.

For an asteroid with an initial radius of 300 metres, spinning fast enough to provide a third of Earth’s gravity, a container would need a radius of 3 kilometers and withstand a drag of about 200 MPa (two hundred million Pas). All this to preserve debris and regolith with a shield thickness of 2 m to protect against cosmic rays. Ambient solar energy can be harnessed using solar panels to aid in the recycling and processing of materials.

“This project started as a way for physicists and engineers to destress, put mundane stresses aside for a while, and imagine something crazy,” adds Peter Miklavitch, a PhD student in mechanical engineering.

In what they call a “wildly theoretical” paper published in the journal Frontiers in Astronomy and Space Sciences, the researchers lay out their ideas. “Our article lives on the edge between science and science fiction,” Frank concluded.