Will humanity ever expand beyond mother Earth? If we did, where would we live, and how?
One suggestion is the development and construction of space settlements that would harbor and nurture colonies of human beings throughout the cosmos. But, what would they look like?
Let's find out about one interesting concept — the NASA Torus Space Settlement.
What is a space settlement?
Before we answer this question, it is important to make the distinction between the act of settling space and the building of "a space settlement". The former is the general process of developing and settling in space, the latter is a specific installation or place in space where people could live, work and, hopefully, raise families — a habitat or colony in space.
It is the latter that we will be discussing throughout this article.
A nice definition of a space settlement is as follows, courtesy of The National Space Society:
"A space settlement” refers to habitation in space or on a celestial body where families live on a permanent basis, and that engages in a commercial activity which enables the settlement to grow over time, with the goal of becoming economically and biologically self-sustaining as a part of a larger network of space settlements. 'Space settlement' refers to the creation of that larger network of space settlements."
To this end, the process of settlement—that some might call colonization—is one that intends to be permanent. With regard to space, this would require providing all the trappings of life needed for sustained, long-term occupation in a particular part of space. Such facilities would also need to provide stability to enable families to survive, to enable children to be born, and thrive.
Space settlements, as opposed to space stations, would need the resources and the equipment to provide shelter, food, breathable air, water, and many other things to enable a stable population of human beings to survive off the world. A space station, by contrast, is not designed for sustained long-term support of a community of human beings, and most of the people who use them are usually scientists on rotation.
In addition, if the colony is to have little to no contact with the planet, there are a few other cited criteria needed for an installation to be considered a permanent "space settlement". These include, but not limited to:
- It should be part of a network of space settlements with sufficient redundancy to survive the failure of any single space settlement.
- It must have sufficient economic specialization to maintain a functional, self-sustaining civilization. This implies schools, universities, hospitals, factories, etc.
Some studies suggest that for a permanent settlement with little contact with the planet to be successful, it will also need sufficient genetic variability in its population. This would require somewhere in the order of at least a few hundred individuals of child-bearing age. Several thousand would be far more sustainable, although IVF and a store of frozen embryos from Earth could also be used to introduce variability
Historical examples on Earth suggest that several hundreds of colonists may be necessary, although one surprising study came to the conclusion that as few as 98 may just cut it.
It might also be possible to reduce the number needed with the right technology e.g. advanced genetic engineering, etc.
Any long-term settlement also needs to provide something for the inhabitants to do. While building the settlement and expanding it will occupy everyone's efforts initially, ultimately the colony might include the establishment of a private sector of some kind, to create businesses and employment, as well as a system of trade.
But these are just some of the considerations needed when planning to build a space settlement.
In summary, a space colony consisting of several settlements could likely have the following characteristics:
- It will feature families who live there on a permanent basis
- These settlements will likely engage in some form of commercial activity that generates the wealth needed to sustain them and not rely on external infusions of resources
- They will need to be large enough and diverse enough to be both economically and biologically self-sustaining
- It is likely they will develop a variety of organizational forms very similar to settlements here on Earth
Some form of government will also be necessary. What form this would take is anyone's guess. Given the dangers present, if rules are not followed stringently, the form of government may not be a democracy.
How much would it cost to build a space settlement?
It is very difficult to make an estimation for something like this, but some early estimates were around $100 billion (+ - $50 billion), according to Gerard K. O'Neill (a former prominent physicist, space colonization advocate, and futurist) in a 1970s article for The Futurist.
For reference, this would be about 2 and a half times the cost of the Apollo Space Program (at around $39 billion in 1979 dollars). Other large-scale engineering projects include the Panama Canal, which cost $2 billion, the Space Shuttle Program that cost $5.8 billion, and the Alaska Pipeline that cost $6 billion. But, of course, those were all on Earth.
Other estimates range from as low as $33 billion for a bare essentials colonization package to over $200 billion for a package with nuclear-powered tugs, space shuttles, orbital bases, and extensive crew rotation.
Any cost estimations would need to factor in a few considerations. These include, but are not limited to:
- The rotation, if any, of the crew during the construction phase of the settlement
- The extent of resupply needed during construction. This will depend on the atmospheric composition of the site and whether food is shipped in water loaded or dry forms
- The composition of the atmosphere at the settlement. Will it replicate Earth's more or less exactly? If so, nitrogen and other gases may need to be shipped from Earth to the habitat. Of course, if the intention is to grow plants at the settlement, soil and other nutrients may also be needed.
What was the Torus Space Settlement?
The Torus Space Settlement, or Stanford Torus, was the principal design considered by the 1975 NASA Summer Study that was conducted in conjunction with Stanford University for a theoretical space settlement design. This study was conducted to brainstorm the possibilities for future space colonization.
It consisted of a torus—or donut-shaped ring—that would be one-mile (1.6 km) in diameter and would rotate once a minute to replicate Earth's gravity in the outer ring.
Earth-normal gravity would be simulated via the centrifugal effect (a component of angular momentum), but would only be experienced on the outward-facing inner surface of the torus.
The design foresaw that it could likely house around 10,000 inhabitants, perhaps even as many as 140,000.
Interestingly, the idea of a large rotating space habitat was not unique to the Stanford Study. Previous similar proposals were made by Wernher von Braun and Herman Potočnik, and have also been featured in science fiction books and movies.
Sunlight would be admitted into the torus by a system of special mirrors, including a large, non-rotating primary solar reflector. The design featured a series of "spokes" that connected to the central hub which would serve as conduits for people, and materials, to travel to and from it to the outer ring.
The hub would act as the main dock for the habitat and zero-gravity activities could be performed in a non-rotating module also attached to the hub. The outer ring would be a living space and should be large enough for a "natural" environment to be simulated.
Population density would, at least initially, be similar to that of a dense city suburb, with parts of it dedicated to agriculture and others to housing and industry.
Some have estimated that the entire settlement would have a mass of roughly 10 million tons. To put that into perspective, the International Space Station has a mass of about 420 tons (or around 330 cars).
By that estimation, the Standford Torus would have a mass of about 7,857,000,000 cars — give or take.
The study went as far as to make proposals as to how the settlement could actually be constructed. For example, the designers suggested using materials from the Moon, flung into space by an electromagnetic catapult (mass driver) to provide the basic raw materials for its construction.
Catapulted material would be captured at the L2 Lagrange point, and would then be transported to L5 for processing and construction. For reference, Lagrange points are areas in space where the gravity of two, or more, co-orbiting bodies are effectively canceled out.
Anything that could not be sourced from the Moon would be imported from Earth. Though asteroid mining was another possible strategy for providing the raw materials needed to complete the settlement.
Whether or not space settlements will ever become a reality is anyone's guess, but there are some who believe that our long-term survival as a species may hinge on colonizing space.
If this is true, then space settlements will form the cornerstone of our expansion into the cosmos.