Dec 20, 2022 I Paul Seaburn

Forget Mars - We May Be Closer to Building Cities on Asteroids

A favorite novel of high school English teachers is “The Little Prince” by French writer and military pilot Antoine de Saint-Exupéry. It tells the tales of a young prince who visits Earth and other planets from his home on an asteroid. The novella’s themes of loneliness, friendship, love, loss and human nature has long put it in a literature class, but today it might fight just as well in a science or physics program. Why? A research team from New York’s from University of Rochester have published a paper laying out how some asteroids can be easily modified to have solar-powered Earth-like gravity for human mineral miners, a protective radiation sheild for safe living quarters and even turn the asteroids into spaceships. If Antoine de Saint-Exupéry were alive today, a sequel to “The Little Prince” might be in order with a less somber, more scientific tone … and a happier ending.

A depiction of the Little Prince on his home asteroid

“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.”

Adam Frank, Helen F. and Fred H. Gowen Professor of Physics and Astronomy, explains in a University of Rochester press release announcing the publication of “Habitat Bennu: Design Concepts for Spinning Habitats Constructed From Rubble Pile Near-Earth Asteroids” in the journal Frontiers in Astronomy and Space Sciences how his team began with a seemingly theoretical idea out of science fiction and “The Little Prince” and quickly discovered that space science has progressed far faster that the authors realized. The project began during the COVID-19 pandemic lockdown when Frank and eventual co-author Peter Miklavčič, a PhD candidate in mechanical engineering, began acting like bored scientists with no lab and kicking around possible applications for O’Neill cylinders. These are the invention of physicist Gerard O’Neill who was tasked by NASA to design space habitats. Since this was 1972, O’Neill came up with two cylinders rotating in opposite directions with a rod connecting them at each end. The spin provided safe artificial gravity on the insides – a concept we’ve seen many times since but has never been successfully implemented. Frank and Miklavčič decided the main inhibitor was the cost of transporting parts and building the habitat in space and began looking for a cheaper alternative.

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

One of the jobs of the Little Prince on his home (and coincidentally house-sized) asteroid “B 612” was to clean the volcanoes. Frank looked at asteroids as flying mountains and tasked the research team of students to convert an asteroid mountain into a habitat. Unlike B 612, most asteroids are merely piles of rubble and have a fraction of Earth’s gravity. Spinning it like an O’Neil cylinder won’t work, so they came up with an alternative.

“Instead, it is proposed in this work to take advantage of the rubble composition and to intentionally disintegrate an asteroid with overwhelming spin so as to capture it into a larger cylindrical external containment structure. In doing so, a thick layer of regolith is created along the interior surface of this structure which forms a shielded interior volume that can be developed for human occupation. Furthermore, by using a stronger external frame the cylindrical habitat can be spun about its central axis to produce an artificial gravity field within.”

To keep the cost down, the “containment structure” would be a giant flexible mesh bag made of ultralight and high-strength carbon nanofibers which would surround and support the spinning asteroid. The rubble would be caught in the mesh and form a protect radiation shield while the asteroid would be solid to support a habitat and have gravity to hold down the humans. “A 300-meter-diameter asteroid just a few football fields wide could be expanded into a cylindrical space habitat with about 22 square miles of living area” that would be “roughly the size of Manhattan,” according to Frank. While the Little Prince’s asteroid only had one house, Frank’s new spinner could support a million people.

In a sense, this is a reconstructed hollow asteroid with the rubble being spun off of the original rock’s surface to form a shell shaped by the cylindrical mesh bag. The rubble found on the surface of most asteroids is nowhere near enough to create a full protective shield, so the team came up with the idea of mounting cannons in the mesh, aiming them at the asteroid and blasting it with projectiles to create more rubble. While the Little Prince might object, this seems like a viable solution.

The research team also considered hollowing out an asteroid to create a radiation-proof inner habitat. This is not viable for rubble-covered asteroids because the loose rocks would not provide an adequate shield. Unfortunately, the more rare solid asteroids would not work either. While they could be hollowed out, the gravity-producing spinning would induce too much stress on the outer layer and cause it to disintegrate. For those who can understand them, the paper does an excellent job of laying out the mathematical calculations the researchers used to determine the tolerances the asteroids could withstand before spinning themselves into pieces. That brings up an important point:

“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.”

According to Frank and Miklavčič, the spinning bag of asteroid violates no laws of physics and can be down using existing materials and technology. Frank concludes with an example that pilot Antoine de Saint-Exupéry, who wrote “The Little Prince” based on his own experiences after crashing a plane in the Sahara Desert in 1935 while attempting to set a speed record, could relate to.

“The idea of asteroid cities might seem too distant until you realize that in 1900 no one had ever flown in an airplane, yet right this minute thousands of people are sitting comfortably in chairs as they hurdle at hundreds of miles an hour, miles above the ground. Space cities might seem like a fantasy now, but history shows that a century or so of technological progress can make impossible things possible.”

A start of an asteroid city in a giant bag?

Will we have to wait a century to live on an asteroid inside of a giant spinning bag? Probably not. Japanese scientists have already sent a mission to the asteroid Bennu and returned with a sample of its rubble, and NASA and the Chinese space program aren’t far behind. Big business has already seen the big potential of mining on asteroids filled with rare minerals and metals. Money drives progress and it could easily push asteroid settlement ahead of establishing a Martian or lunar colony. The Little Prince might not like that aspect of human nature, but this is almost 2023, not 1943 when the book was written.

Antoine de Saint-Exupéry's aircraft disappeared over the Mediterranean in July 1944 while attempting to move what was still the new science of flying forward, and “The Little Prince” was published posthumously. A city on an asteroid might be the perfect tribute to him and his book.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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