New Article: A Trillion Tons in Orbit
The physicist Gerard O’Neill thought a planetary surface isn’t the right place for an expanding civilization. As launch costs fall, we need more ambitious goals to drive technology further.
This article by Brian Balkus was published in our Spring print edition PALLADIUM 17: Universal Man on March 26, 2025. Subscribe now to receive your copy of our latest edition.
On December 7, 1972, NASA astronauts landed on the Moon for the final time. The Apollo 17 crewmen spent several days exploring the Moon’s Taurus-Littrow valley on a lunar rover and collecting rock samples. As the crew prepared to return home, astronaut Jack Schmitt gave a short speech saying “We shall return, with peace and hope for all mankind.” Back on Earth, his words were largely ignored. Rather than show the astronauts’ final steps on the Moon, NBC chose to replay an old episode of the Tonight Show. The novelty of Moon missions had worn off and Americans had moved on. NASA’s budget, which peaked at nearly 5% of the federal budget in 1965, declined to a mere 0.98% of the budget by 1975. It sits at just 0.3% today.
Gerard O’Neill, a physicist at Princeton University who had previously applied for NASA’s Astronaut Corps, was dismayed at the growing apathy about space and the future that he was seeing in his students. To inspire them, he began a weekly freshman seminar in 1969 for a group of eight to ten students focused on large-scale engineering problems that could benefit a broad spectrum of humanity. The theme of his first seminar was “Is a planetary surface the right place for an expanding technological civilization?”
Over the course of the seminar, O’Neill and his students considered if, instead of colonizing Mars, we should build a megastructure that could serve as a space colony. Looking at the possible constraints of such a project from first principles, they began to realize they were solvable. This included an analysis of the economics, safety, simplicity, and ruggedness of every element of the megastructure’s conceptual design. While O’Neill initially regarded the class project as a kind of “joke,” the results of this analysis prompted him to take it much more seriously.
The design concept the group settled on became known as “O’Neill cylinders.” These were to be vast space stations dwarfing the small scientific outposts of the 1970s such as Skylab or the contemporary International Space Station, and featured a pair of 20-mile long cylinders with three land areas alternating with three vast windows, plus three mirrors that open and shut to create a day-night cycle. The cylinders rotate in opposite directions, enabling them to remain aimed toward the sun and generating a centrifugal force that simulates the effect of gravity.
Dreams of O’Neill Cylinders and space colonization faded away along with NASA’s budget. But fifty years later, the capabilities of SpaceX’s Starship rocket have created hope that space colonization is within our grasp. The currently active Block 2 variant of Starship can deliver up to 150 metric tons of payload to low Earth orbit per launch surpassing the capacities of the Saturn V rocket used by the Apollo missions. The planned Block 3 variant is estimated to be capable of payloads of up to 200 metric tons per launch.
The capacity to deliver thousands of metric tons of payload to low Earth orbit at a much lower cost has quietly made a manned Mars mission viable. In light of this, NASA’s plans to send humans to Mars in the next decade as part of its Mars Exploration Program, to determine if the planet can become a habitable world, are surprisingly credible.
Mars colonization is widely viewed as the logical end point for the first phase of space exploration. But we should again be asking if this is the right goal, and whether Gerard O’Neill’s vision represents a better path to colonizing space and a better driver of technological development.
A Thousand Strongholds of Mankind
The general concept behind O’Neill Cylinders dates back to a 1954 book titled People in Space—New Projects for Rockets and Space Travel by Hermann Oberth, one of the founding fathers of modern rocketry. The science fiction author and writer of the screenplay for Stanley Kubrick’s 1968 classic 2001: A Space Odyssey, Arthur C. Clarke, portrayed a similar concept constructed by an alien intelligence in his 1973 science fiction novel Rendezvous with Rama.
What made O’Neill different was that he provided scientific authority to the idea. He was an accomplished physicist who was on the short list for the Nobel Prize for his invention of the “particle storage ring,” a technique that allows particle beams to collide head-on in accelerators. Ultimately, other physicists would go on to win the Nobel Prize due to work enabled by his invention.
By lending his credibility to the O’Neill cylinder concept, he was sacrificing scientific authority, and he knew it would likely end any chance of his winning the Nobel Prize. But for a man who dreamed of exploring space himself, the concept was too technically sweet not to publish. In 1974, Gerard O’Neill published an article in Physics Today detailing the O’Neill cylinder concept, and followed up with the book The High Frontier: Human Colonies in Space in 1976. O’Neill began working with NASA to further his concept and briefed Congress on his plans in 1975.
The High Frontier depicted three space structures, dubbed “islands,” that were located at Lagrange points—areas of gravitational equilibrium where objects remain relatively stationary—in the Earth-Moon system. They would be constructed in sequence, with each stage advancing in complexity and ambition. The first two islands were rotating spherical shells that resembled large green valleys located around the equator of the sphere. The third island was two O’Neill Cylinders, which would be built using raw material from the Moon and near-Earth asteroids.
The material would be transported to the site using an electromagnetic catapult concept called a mass driver, a non-rocket method of space launch that is viable on astronomical bodies with no atmosphere, which in turn would necessitate powered flight overcoming drag. The in-space sourcing of materials was critical to success, because launching material from Earth would make the whole project prohibitively expensive. After the mining infrastructure and mass drivers were built on asteroids and the Moon, and the O’Neill Cylinder concept was proven, more and larger cylinders could be built at ever-decreasing costs.
There was a political element to Gerard O’Neill’s vision that was influenced by the Malthusian concerns reflected in the popular book The Population Bomb by Stanford professor Paul Ehrlich. The book depicted an overpopulated world riven by social catastrophes, military conflict, industrial pollution, extinction of entire ecosystems, and a perpetual energy crisis. In an interview alongside O’Neill, the famed science fiction author Isaac Asimov mused about achieving world peace by building “an Israel in space, a Palestine in space, a Northern Ireland in space.”
Unlike our slowly centralizing home planet, where land and sovereignty have long been parceled out, there could be a political and demographic exit for those seeking escape. The centralizing trend in politics is perhaps true for all planetary civilizations, as, for example, a Martian colony would naturally trend towards centralization due to both the resource demands as well as the need for a political body with planet-wide sovereignty necessary for the terraforming process. O’Neill Cylinders offer the promise of political experimentation and competing systems and ways of living. If residents are unhappy in one settlement, they could have the right to exit to another.
To further O’Neil’s vision, a NASA Summer Study exploring designs for space colonies was held at Stanford University in 1975. As part of the study, a similar concept to the O’Neill cylinder that could house up to 140,000 people was developed and became known as the Stanford Torus.
No one disputed that the fundamental conceptual elements of both designs were scientifically sound and could be built with sufficiently advanced technology. But the technological breakthroughs that would be required were far outside of humanity’s grasp—as was the cost. In 1976, O’Neill estimated a project to build an O’Neill Cylinder capable of housing one million people would cost $3 trillion, or $1.1 trillion more than the entire U.S. GDP at the time.
The Charismatic Yet Lethal Red Planet
That NASA would devote resources to studying space megastructures, and that Gerard O’Neill was asked to brief Congress on his concepts, illustrates a difference in acceptable levels of ambition between then and now. The same year the Apollo Program ended, President Nixon canceled a government initiative to build a supersonic commercial passenger jet and U.S. government spending on space exploration and scientific research and development as a percentage of GDP began what would turn out to be half a century of decline.
But despite this decline, the U.S. never gave up on the old idea of reaching Mars. The dream of reaching a new world was simply too interwoven with the political legitimacy of the U.S. itself—since the American people were the descendants of those who had ventured to and laid possession of a new world as a cornerstone of their nation's sovereignty. The thought of astronauts planting the American flag on Mars and exploring another world was too compelling. It was inevitable that every president would attempt to borrow at least some of that political authority for themselves. From 1980 through today, Bill Clinton was the only president who did not direct NASA to work towards a manned Mars mission.
As soon as men invented modern rockets, they began dreaming of visiting the Red Planet. In a 1987 interview, Hermann Oberth recalled the Mars “furors” of 1907, 1909, and 1916, when Earth was very close to Mars and there was widespread speculation about potential life on Mars. This curiosity was shared by Wernher von Braun, who started his career as an apprentice to Oberth, and after designing the V-2 rocket for the German military in World War II, would go on become the chief architect of the Saturn V rocket that put men on the Moon. Like Oberth, von Braun attracted talented engineers to work on his projects by setting ambitious and technically interesting goals and presenting them either in technical papers or science fiction.
SpaceX founder Elon Musk today applies some of the same methods used by the German rocket scientists, and has produced videos and documentaries advocating Mars colonization and promoting the company itself. It is SpaceX’s focus on the goal of taking people to Mars that helps it attract elite engineering talent. It is these engineers who are willing to work exceptionally hard to help make humanity multiplanetary. Even though the majority of SpaceX’s revenue comes from defense contracts and Starlink services, the company couldn’t have recruited comparable talent if they had set such breadwinning as their ultimate goal. It is Musk’s grasp of how to use social technology to advance material technology that made Starship possible.
Musk doesn’t downplay the risks inherent in the mission, noting “a bunch of people will probably die" on Mars—just as colonists did when settling the New World. The Red Planet is an unremittingly hostile place for human life. Its thin atmosphere provides almost no shielding against cosmic radiation and is composed mainly of carbon dioxide, making the air unbreathable. Martian colonists would be exposed to radiation doses up to 700 times higher than Earth’s, which could cause severe damage to the central nervous system, cancer, cardiac disease, immune system weakening, and DNA damage resulting in mutations and genetic abnormalities.
Martian colonists would need to remain in pressurized suits, without which the fluids in their body would boil due to low atmospheric pressure. They would also have to deal with an extreme climate where temperatures fluctuate from up to 20 degrees Celsius during the day to negative 70 degrees Celsius at night. This thin atmosphere is also unfortunately thick enough to make non-rocket means of space launch like mass drivers impractical—putting a floor on how low launch costs from an industrial Martian civilization can go. The Earth-Luna system might yet have a permanent advantage there, in its atmosphere-free special economic zone.
Because Mars only has 38% of the Earth’s gravity, astronauts could suffer from vision problems, weakened bones, muscle atrophy, cardiovascular deconditioning, and a weakened immune system. While decades of study have provided us with an accurate medical model of microgravity, we do not yet have any long-term understanding of mere low gravity. Can a pregnancy be brought to term at less than half the Earth’s gravity? We simply don’t yet know.
Terraforming Mars to make it more hospitable to human life would likely take hundreds if not thousands of years. This might be a viable political project for a thriving Mars civilization, as that world’s manifest destiny. But there is yet no merely economic or politically expedient justification for such an effort and resource expenditure for us here on Earth. As with the Apollo Program, once the novelty wore off, sustaining spending at the necessary levels would be politically very difficult.
One of Musk’s stated reasons for Martian colonization is the existential risk posed to humanity by only being on one planet. A nuclear war or a planet-killing asteroid strike could wipe out human life forever. But this is as much an argument for spending money to prevent existential risks on Earth, such as investing in technology to enable planetary defense from asteroids. In addition to the romance of a new landmass to settle, part of the fixation on Mars is driven by what the science fiction author Isaac Asimov termed “planetary chauvinism.” We are simply used to living on a planet, so we assume that the only place humans can live on permanently must be another planet. But O’Neill Cylinders can provide all of the benefits of a planet too.
Escaping Planetary Limits
One of O’Neill’s students at Princeton in the 1980s was Jeff Bezos. Bezos was a former child prodigy who was obsessed with space from the age of five and gave his high school valedictorian speech on space colonization. Only six years after founding Amazon, Bezos started the space exploration company Blue Origin, and would later purchase a 400,000 acre ranch in Texas for rocket testing. Unlike SpaceX, whose founding mission was driven by Elon Musk’s aim to enable Mars colonization, Bezos’s goal was for Blue Origin to “build the necessary infrastructure for future generations to have an entrepreneurial explosion into space.”
In Washington, D.C. in 2019, Bezos delivered a presentation titled “For the Benefit of Earth” that illustrated his ultimate ambitions for Blue Origin. Bezos spoke of building multiple O’Neill Cylinders holding a million or more people. The interiors of the cylinders could resemble architecture on Earth or take on a more science fiction-infused appearance. The climate could be like a perfect day on Maui or any other climate its residents desired. Some cylinders would be vacation destinations and offer “zero-G gravity so you can go flying with your own wings.”
Residents of the cylinders could return to Earth for vacation and, if anything went wrong, people on Earth could quickly respond with help. This, in the early stages, represents an important advantage over planetary colonization, since if anything went wrong on a Martian colony, it would take six months for help to arrive. Any Martian colonists would be on a distant island in an environment that is doing everything it can to kill them.
In Bezos’s vision, much of Earth could be converted into a kind of giant national park with industrial production moved to space. Truthfully, it is perhaps at least as likely that Earth would become the densely populated and greatly desired Manhattan of the elites of the distant future, as it is to become something like a nature-conserving Yellowstone Park. After all, natural habitats can be recreated in orbit just as easily.
One of Bezos’s presentation slides was labeled “Our Choice: Stasis & Rationing or Dynamism & Growth.” In place of the Malthusian concerns of the 1970s, degrowth movements have emerged with renewed concerns about ecological devastation and resource exhaustion. The resources on Earth are not infinite and at some point in the far future we will have to move beyond this planet or live in a world filled with competition over a shrinking supply of everything needed to sustain civilization.
Elon Musk was quick to dismiss Bezos’s vision as mere fantasy, pointing out that building an O’Neill cylinder was like trying to build the “United States in the middle of the ocean.” Perhaps the decentralized dream really is too similar to seasteading concepts. The cost and difficulty of transporting massive amounts of mass from the Moon and asteroids to build colonies is beyond today’s economies.
Further Technological Progress Will Only Happen With Goals Worthy of It
We have not yet reached the technological peaks required to build space megastructures. But this is more of a reason to pursue such a project, as it would function as a replacement for war as an impetus for large-scale technological progress and unlock completely new technologies we would otherwise have never developed. It was World War II that enabled the development of radar, jet engines, programmable general-purpose digital computers, long-range guided missiles, the atomic bomb, and more, over a six-year period.
The developmental benefits carried over to the Cold War, with NASA itself a thinly-disguised military organization. When NASA was founded there was open speculation in Washington about satellites armed with nuclear missiles and military moon bases, with some influential figures believing “mastery of outer space meant mastery of the world.” Military and NASA spending in the 1960s created the industrial structure and financial strength needed to pursue ambitious commercial projects and advance nascent technology. By the mid-1960s, NASA was purchasing sixty percent of the integrated circuits produced in the United States, which led to the development of Silicon Valley.
The English novelist J. G. Ballard once compared the Boeing 747 airplane to the Parthenon, writing that each gave shape to “mathematics, aesthetics, and an entire geopolitical worldview.” The U.S. was able to achieve geopolitical dominance because it possessed technical capabilities no other nation possessed and were impossible to replicate. The Soviet Union bankrupted itself trying. In some ways, the U.S. is still living off the fumes of the technological advances made in the 1960s. A replacement of parts of the military-industrial complex with a space-industrial complex focused on building space structures could enable step change technological improvements across a wide range of areas.
In the half-century since O’Neil gave his estimate of $3 trillion as the cost for space habitat for one million people. While dollars buy less today than in 2025 due to inflation, some technologies have continued to advance and soundly beat inflation. For example it cost approximately $1,311 in 1976 dollars for Saturn V to bring a kilogram of mass into low Earth orbit, this works out to about $7,000 in today’s dollars. Starship is currently estimated to bring down costs as low as $150 per kilogram for single-use missions and perhaps as low as $25 per kilogram with high reusability. This means a key cost is perhaps two orders of magnitude cheaper than half a century ago!
Which other factors might have changed drastically? Without a funded and clear detailed technical study, we don’t yet know. In the political moment of a Musk and Trump alliance presenting such a study to congress seems less farfetched than last year. A current technical presentation on orbital habitats might prove to be the best stimulus bill that the legislative body ever considered since science fiction projects can only be built by a science fiction industrial base.
A selection of the technical advances that a structure on this scale would provide reason to develop could include self-replicating and autonomous construction and asteroid mining robots, extraordinarily strong and flexible materials, ultra-efficient water purification and recycling, hydroponics, and air filtration. Or maybe basic atomic manipulation to create materials and objects on demand, along with the ability to convert carbon to food and chemicals, as well as fusion power and space-based solar energy, among many other technologies. All of these technologies would transform life on Earth forever.
A program to develop O’Neill Cylinders or any other habitable megastructures in space is in reality a program to develop a post-scarcity society on Earth and extend human civilization throughout the universe. It would require a sequential approach starting with a Moon colony and asteroid mining before the construction of a pilot project. The first structures may be built on asteroids themselves, with near-Earth asteroids such as Bennu viewed as plausible construction sites.
Human history is filled with stories of exploration and discovery. Space is the final frontier. But perhaps we should be thinking of ourselves as engineers, rather than explorers. The goal shouldn’t be to settle a new planet like we once settled a new continent, but to build new artificial worlds of our own design.
Brian Balkus is a senior director of strategy at an energy infrastructure firm.