Tag Archives: space habitats

The first generation space habitats

Space colonization will be a process with multiple stages, on this site we usually discuss the latter stages of this process. However, it is important also to discuss the earlier stages. These earlier stages will be characterized by small human presence in space and extensive use of robotics and teleoperation.

As space colonization will develop, the number of humans is space will grow. Hence we distinguish between different generations of space settlements. The first generation of space habitats are dumbbells and similar designs. The second generation consists of Bernal spheres and toroidial designs. And the third generation consists of O’Neill cylinders.

The second and third generation of space habitats, as defined above, are large structures designed for large populations. The reason why these designs are large, is because they use centrifugation to replace gravity. The centrifugal force depends on the product of the radius and the angular velocity. A larger radius requires a lower angular velocity, which is preferred by most humans.

Both the Bernal sphere and the Stanford torus have a radius in the order of a few hundred meters, which implies about one revolution per minute. Their designs require a lot of material resources, however. On the other hand, these designs also provide living space for tens of thousand people.

First generation space habitats will also use centrifugation to replace gravity, but use a simpler design which would require less material. But consequently provide room for fewer people. Though this is not really an issue in the early stage of space colonization.

The dumbbell habitat design consists of two modules, with an equal mass, which are connected with each other with a tether. The structure rotates around its midpoint, halfway the tether, and hence generating a centrifugal force.

The tether can be of any desired length, while there no special size requirements for the two modules. Even if the tether is a few hundred meters long, the material requirements will be modest. The modules themselves are similar to those of the international space station, though we could also opt for the inflatable modules of Bigelow Aerospace.

A similar design is the bola space habitat.

Dumbbell habitats will serve as a first base for asteroid mining and the construction of next generation habitats. Depending on the size of the modules a few dozen people will stay at the habitat.


O’Neill Cilinders

The first two videos are uploaded by CentripetalWorlds. Both feature O’Neill cylinders, video one appears to show, the construction of an O’Neill cylinder.

Two rotating O’Neill cylinders (warning: annoying sound, please mute volume).

A different but related design, the Kalpana One:

The Kalpana One is an interesting design, and quite suitable for the first generation of space settlements (O’Neill cylinders have been considered as a second generation space habitat since they were designed).

For a technical discussion of O’Neill cylinders, by no one less than O’Neill himself, see here.

Exterior view of a double cylinder colony

Time zones and separation of functions









Lagrange points

Talking about and referring to Lagrange points can be confusing, since there are Lagrange points in every system in which one celestial body orbits another. So when talking about Lagrange point colonization, one need to specify which system he is referring to.

Republic of Lagrangia is in favour colonizing the 4th or 5th Lagrange point of the Sun-Earth system. Since it’s quite cumbersome to repeat this phrase all over again, we will from now on simply refer to these points as SEL-4 or SEL-5, with SEL standing for Sun-Earth Lagrange point. This system allows us also to easily refer to other Lagrange points: SML for the Lagrange points of the Sun-Mars system, or SJL for the Sun-Jupiter system.


The Main Asteroid Belt (MAB), or simply the Asteroid belt, consists of those asteroids which orbits are between the orbits of Mars and Jupiter. These asteroids are called main belt asteroids (MBA).

There are also asteroids outside the MAB. Those asteroids which orbits are (at least partially) within the orbit of Mars are called Near Earth Asteroids (NEA).

Trojan asteroids are asteroids which have been trapped into a system’s L4 or L5. Most famous are the Jovian Trojans, but also Martian, Neptunian and Terrestrial Trojans have been discovered. Especially the last are of particular interest, since a population of Terrestrial Trojans will provide the mineral resources needed to build space habitats and for export to Earth.

At this moment the existence of one Earth Trojan Asteroids has been confirmed, but scientists believe more Earth Trojans should exist.

Space habitats

A space habitat is a space station designed for hosting a permanent population of a substantial size. Space habitats, also known as space settlements, are located in free space as opposed to colonies on or under the surface of a celestial body. When we talk about space colonization, we mean the creation of space habitats.

How high can we build in a space habitat?

Living in a space habitat is quiet different from living on the surface of a planet. On Earth our head is oriented outwards, i.e. our head is pointed away from the centre of the Earth. But in a space habitat our head is oriented inwards, pointing towards the centre. Therefore we cannot build higher than the distance between the wall of the habitat and its centre, but this is not the only, or even most important, restriction for the height of building in space habitats.

In a space habitat gravity is replaced by the centrifugal force, which is generated by rotating the habit around its axis. This (virtual) force is given by the following equation: Fcent = m(w^2)r (I have used ‘w‘ instead of the small omega, since I don’t know how to type Greek letters in WordPress), with m the mass of the object on which the force acts, w the angular velocity of the habitat and r the distance between the object and the axis. On Earth gravity is given by the equation Fgrav = mg, with g the so-called gravitational acceleration, which is (on average) g = 9.81 m/s^2.

If we want that the centrifugal force acting on the inner wall of the space habitat (which we will refer to as “street level”), we have to solve Fcent = Fgrav. Or

m(w^2)r = mg

We see that we can cancel m on both sides of the equation, and write

(w^2)r = g = 9.81

Since r is in fact nothing else than the radius of our space habitat (which would be in case of an O’Neill cylinder be 3,000 meter), and hence a design parameter, we can only play with the habitat’s rotational speed in order to fix the strength of the centrifugal force.

A consequence of the last equation, the larger the radius of a space habitat how smaller its angular velocity will be. But also that by a given w, the closer you are to the axis of rotation, the smaller the centrifugal force acting on you will be. At the axis of rotation the centrifugal force is zero.

The whole point of substituting gravity with centrifugation is to counteract the health effects of low or zero-gravity. Therefore the height of a building will be restricted by the minimum accepted level of gravity. Recall that in a space habitat we are building towards the axis. So the question of height becomes a question of what is the accepted minimum gravity?

Gerard O’Neill have suggested that 70 % of Earth’s gravity, or 0.7g is an acceptable minimum level of gravity. Our equations show that for a given space habitat the strength of the centrifugal force is linearly dependent of the distance to the axis of rotation. Hence 0.7g is present at 0.7r, or at 0.3r if we are counting from street level. Assuming r = 3,000m than we can erect building up to 900m (counted from street level).

Quality of life and Space habitats





See also:

Public transportation in O’Neill cylinders

Manifesto part 1

Reasons for Space colonization

In this section we will explain why we are in favour of space colonization, and the next section we will also explain why we want to colonize the so-called fourth and fifth Lagrange points of the Earth-Sun system rather than colonizing the Moon or Mars. Although many of our arguments are not original, actually most of our main arguments exist since at least the late 1960s, we will present our reasoning from a point of view which is based on classical republicanism and classical liberalism.

Traditional arguments for space colonization are overpopulation and the survival of humanity. Since the world population continues to grow, some people fear that at one time in the (near) future there are too many people. Overpopulation is the situation that there are more people on Earth than our planet can sustain (this is the idea behind the ecological footprint). Believing that birth control programs will not work or will be insufficient, some people believe that therefore a part of our species should be relocated to other planets or to artificial space habitats. The fear for uncontrollable population growth was especially great in the 1970s (see for instance the establishment of the club of Rome). Since then the growth rate of the world population has declined, and many experts now believe that the number of humans will stabilize at nine to ten billion by the year 2100. Of course we cannot predict whether there will be a baby boom somewhere in this century, but it is unlikely that the world population will triple during the next 100 years.

There are several so-called existential risks for humanity, varying from natural to man-made catastrophes. The idea is that in order to guarantee the continued existence of the human race, a part (or even all) of humanity should be relocated into outer space, in the event of a global catastrophe. However some of those potential catastrophes, especially those created by man, can either be averted or their consequences can be reduced. Other potential risks are only a problem in billions of years, which raises the question why we should take action right now, while there are more urgent problems (like the HIV/aids pandemic). Some people, like for instance the Voluntary Human Extinction Movement, would argue that humans shouldn’t reproduce in the first place, and therefore such far-into-the-future problems, such like the Sun entering into the red giant stage, are irrelevant. Given that the chance for a global catastrophe which is able to wipe out the human species, to happen within the lifespans of all currently alive people is rather small, we can ask whether we have a moral responsibility to ensure the continued existence of mankind. Different people will answer this question differently.

Traditionally there is also a third reason for space colonization. Although this one is not as popular as the first two, but we believe this third argument is possibly more important. We could call this one the economic argument (we could call the first and second argument the demographic respectively the survivalist argument). As more people are the joining the global middle classes, more people will buy cars, washing machines and other consumer goods. In order to meet this increasing demand, more and more resources are needed. If for example every person on Earth would be able to buy a car, we should switch to, for example, hydrogen cars. But the required fuel cells need a lot of platinum, and everyone knows that platinum is a very rare resource, at least here on Earth. Asteroid mining could easily provide enough platinum for a full-scale hydrogen economy (I will ignore all criticism of the hydrogen economy here, because that is outside the scope of this manifesto). Beside solving issues of resource depletion, asteroid mining can also reduce or eliminate environmental damage caused by terrestrial mining. The reader may point out that asteroid mining is not the same as space colonization. This is true, but asteroid mining without space colonization is practically impossible. Even if we have a nearly completely automated space mining industry, we still need a (small) space based crew in case of some unexpected problems.

However, we believe that the most important reason for space colonization is what we would call the political or utopian argument. Here on Earth civil liberties are under pressure almost everywhere, and since many resources (e.g. food and oil) are increasingly becoming scarce we expect that political freedoms will be even further restrained. Except for a piece of Antarctica known as Marie Byrd Land, almost all land on Earth is claimed by governments. Therefore it is almost impossible to create a new country on Earth without war. Secondly it is hard to impossible to implement large reforms in existing societies, see for example the massive demonstration currently held in many European countries.

Republic of Lagrangia believes that every society, whether on Earth or in Outer Space, should have the right to organize themselves as they see fit. We also believe that every person should have the right to choose in which society he or she wants to live. Therefore we do not believe in forcing existing terrestrial societies to implement the reforms we wish to implement, our only option is to move to Outer Space.

We realise that different people want to live in different kinds of societies, but the beautiful aspect of Space Colonization is that it provide both the space and the resources for a wide variety of societies. Suppose that one group disagrees how some Space community is run, they can simply take their stuff and go to somewhere else to create their own community. No need for violent separation movements and related civil wars.

Peaceful coexistence will be the cornerstone of the relation between Space Nations, people will move to those societies they like most or they will try to create their very own. This kind of freedom does not exist on Earth nowadays.

O’Neill Cylinders and spatial planning

This post was originally posted on blogspot.com on October 18, 2012

















Planetary chauvinism

This post was originally posted on blogpot.com on July 31, 2012

In this post I will deal with the subject of planetary chauvinism and more specifically I will explain what planetary chauvinism is and why it is dangerous.

Essentially planetary chauvinism is the idea that human life should be based on the surface of a planet or planet-like object, such as the moon. In several earlier posts I have presented my objections against terraforming, lunar settlement programs and the colonization of Mars. All of these “space” colonization proposals are based on planetary chauvinism.

The origins of planetary chauvinist attitudes are simply based on psychology and ignorance. Many people believe that since humans have always lived on a planetary surface for ever we should do so in the future. Of course this is a logical fallacy, some practices we humans have done for centuries, slavery for instance, are now universally rejected or abolished. The other pillar of planetary chauvinism is ignorance, although many are familiar with space station like mir and the ISS, not very much people seem to know about the designs of space habitats capable of accommodating several thousands of people. Nor are there many people who realize that asteroids instead of planets or the moon are the true treasures of our solar system.

The question is why planetary chauvinism is dangerous. Many so-called “space programs”, regardless whether they are pursued by governments or private parties, are focused  on creating permanent bases on the moon or Mars. Although a lot of people seems to know about the dangers of low gravity on human health, the simple solution, rotating space habits in free space, is almost unknown outside the space advocacy movement. Not only is the low gravity of the moon and Mars a problem, but space habitats are actually cheaper than terraforming Mars, building domed cities on the moon. Why should we waste money on settling other planets, while with less money we can do the same job with free space habitats?

But the main danger of planetary chauvinism is that it will undermine the public support of any future space settlement program. Many ordinary people nowadays associate space colonization with settlements on Mars or on planets in other system. Since most people understand that these projects are costly and will take centuries to complete, they will tend to argue not to spend any money on those projects, regardless whether this is through taxation or private donations.

Planetary chauvinism with its narrow mind undermines the attempts to show the general public the real prospects of space development programs: the utilization of the resources from Near Earth Objects and the creation of space habitats. And by doing so planetary chauvinism is working against any serious space settlement program, therefore it is important to combat planetary chauvinism.