A Home on the High Frontier

Last week saw the launch of two of the most powerful rockets ever flown. On 16 January, SpaceX’s Starship was launched for its seventh test flight and its first stage booster was successfully caught—even though the upper stage was lost in a quite spectacular manner.

Earlier on the same day, New Glenn, the flagship of Jeff Bezos’s space company Blue Origin took its maiden flight. Although the company’s much smaller New Shepard vehicle has performed many sub-orbital flights, this is the company’s first orbital vehicle. New Glenn is a similar vehicle to Falcon 9, but larger, and like Falcon 9 the first stage is designed to be recovered on a ship. On this first flight, recovery was attempted but the booster was destroyed as it entered the atmosphere. They are widely expected to get this right on subsequent flights, though and become a competitor to SpaceX.

Blue Origin’s entry into the reusable orbital launch market has rekindled popular interest in a billionaire space race between Elon Musk and Bezos—and sometimes Richard Branson—but in fact there is no such race—or, at least, things are not quite as they may seem. Because Musk has been the most publicly vocal about his plans, a lot of people believe that these three men are in a race to get humans to Mars. But Jeff Bezos does not want to send people to Mars, as he pointed out in a speech at the George W. Bush Presidential Centre in April 2018:

My friends who want to move to Mars? I say, “I have an idea for you. Why don’t you first for a year move to the top of Mount Everest. Because the top of Mount Everest is a garden paradise compared to Mars.”

It is not hard to figure out who this comment was directed at. Bezos is inspired by a vision that does not involve living on Mars—or on any planet besides Earth for that matter—but envisages human beings inhabiting artificial worlds in free space. The concept dates back to the 1970s, and the work of Gerard O’Neill.

As a professor at Princeton, O’Neill developed, alongside his students, an alternative vision for space colonisation in which habitats would be constructed at gravitationally stable points called Lagrange Points in the vicinity of the Earth and Moon and made to rotate so that the centrifugal force felt by occupants would simulate gravity. Such stations would offer vastly more living space than is available on all the planetary surfaces in the solar system, and he therefore concluded that they would provide better locations for an expanding interplanetary civilisation in a repudiation of what Isaac Asimov jokingly referred to as the “planetary chauvinism” of science fiction.

O’Neill published a book entitled The High Frontier, which fleshed out his ideas, and lent his support to a NASA study that investigated the practicability of building such a habitat. He was reasonably well known at the time, having been interviewed on television about his ideas, but despite his immense influence in the space community he has since been largely forgotten by the broader public. His concepts enjoyed a brief popularity but then fell out of favour both because of political attacks from critics who disliked the idea of NASA spending money on such things, and because of the growing understanding that the Space Shuttle was never going to provide the cheap, regular access to space that such a project would require.

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But things are different now. In 2024, SpaceX launched more rockets in a single year than the Space Shuttle did in its entire thirty-year lifetime, and at a fraction of the cost per kilogramme. Cost effective reusability—something that has always evaded the Shuttle program—is the key and following SpaceX, Blue Origin and other companies hope to provide it. Concepts that were constrained by launch costs a decade ago can now be considered seriously, including the construction of space habitats.

The amount of mass that needs to be moved into space to create such habitats is very large though. Providing gravity by rotation requires keeping the rate of spin low—4–6 revolutions per minute is the likely maximum humans can adapt to, and most designs aim lower to ensure that everyone can acclimatise easily—and to provide Earth-standard gravity at this rate of rotation necessitates a large radius. The largest habitat proposed by O’Neill—which he referred to as his “Island 3” design but has since become known as the eponymous “O’Neill cylinder”—was 8 kilometres in diameter and 32 kilometres in length, allowing the rotation rate to be kept under 1 rpm. Such a habitat would have a mass of billions of tonnes, far too much to be launched from Earth even in the new age of low-cost launches.

O’Neill understood the problem and was working on a solution, in the form of in-situ resource utilisation or ISRU. The overwhelming majority of the mass required for space habitats would be sent not from Earth but from the Moon. His plan, fleshed out in the NASA Space Settlements Study, was to construct a mining facility on the Moon and a device called a mass driver. This was a series of coils that would accelerate containers of lunar regolith to escape velocity horizontally along the surface, exploiting the lack of atmospheric drag to provide a very cheap launch system. O’Neill and his colleagues built a number of sub-scale prototypes of such a device and demonstrated them in the lab.

This is a key difference between the O’Neill’s vision and the Mars approach to space colonisation—once you put humans on Mars, they can start building a base straight away. Space habitats require a significant upfront investment, but in return you get an environment that is much closer to that of Earth, and it is situated closer as well, meaning that people would be able to travel to and from the habitat in a matter of days at any time, while journeying to Mars takes around six months and the trips can only be undertaken during windows 26 months apart.

Philosophically, the O’Neillian approach requires a bit more patience, though its early supporters did not seem to realise it. When the concept was first proposed in the 1970s, advocates formed the “L5 Society” (named for the 5th Lagrange point located in the vicinity of the Earth and Moon, at which the first colony would be located) to lobby for the concept and sported slogans such as “Lunar Mine by ’89” and “L5 by ’95”. However, humanity was not undertaking huge deep-space infrastructure projects during the Seinfeld years. The early supporters of O’Neill believed that NASA would provide the funds, and that the Shuttle and derived hardware could perform the task on a twenty-year timescale, but both assumptions were far off the mark.

In the 1970s, it was widely believed that the Shuttle would fly fifty times a year and have per kilogramme costs to orbit comparable to those we see from Falcon 9 today. Space colonisation studies at the time treated this as a given, because after all NASA had landed a man on the Moon from a standing start in less than a decade, so their promises of cheap routine space access should be credible, right? In reality, the Shuttle never managed more than nine flights in a year, and cost much more per kilogramme than contemporary expendable launch vehicles. After the initial burst of publicity, and some cooperation from NASA, the space colonisation project was viciously and unfairly criticised by politicians, and NASA distanced themselves from it.

The successor to the L5 Society, the National Space Society, avoids such aggressive timetables. Bezos himself has spoken about building a “road to space,” which would provide the infrastructure for the next generation to continue the project. He has started a “Club for the Future” to inspire children to take up the challenge where they leave off. In Blue Origin’s own publicity material, the effort is likened to building a cathedral. This may be a conservative estimate of the timescale, though. Given recent advances in automation and manufacturing, there are reasons to think that the utilisation of space resources could accelerate faster than expected. Watch this space to see what is achieved over the next few years by Blue Origin and other companies investing in this.

Elon Musk, on the other hand, is not interested in industrially developing the Moon—a project that he dismisses as a “distraction” from getting a Mars base up and running as quickly as possible. This makes sense given his objectives, but it shouldn’t dissuade Jeff Bezos or anybody else from taking an alternative path. The merits of these two competing schemes for space colonisation have been debated by engineers, scientists, and advocates for decades, but now that there is real money behind attempts to implement both schemes, the matter can be settled by actions. Whatever happens, the future in space is going to be incredible.