Bryden Allen's Website

A Full Space Colony

(500 people and fully self-reliant)

"O'Neill's Cylinder"

Nobody really knows what a practical Space Colony will look like. I, like most people, imagine that such a colony will be something between the current International Space Station and the fanciful dreams expressed in "O'Neill's Cylinder". The version I propose here then is just the most practical, healthy colony I can imagine.
            This colony should be roughly in the same orbit as the current International Space Station. In this situation, it is easier for me to do the calculations as to how much such a project will cost. (Besides this is a sensible orbit, because then people can then return to Earth, if something goes wrong.)



The figure shows the basic facilities, which the colony must possess. (The full sized version of this picture is given on the back inside cover of this book.) This diagram is in profile - so you have to visualize what the depth dimension looks like yourself. However, the depth dimension will mostly be the same as the height dimension, which is shown. The sun is on the left. The tubes are, of course, for access between the various facilities. These tubes would mostly be about 2 m wide for easy human access in both directions. But the tubes to the recycling plant and the material conversion facilities need to be a little wider. This is because substantial amounts of material need to be passed through these two tubes as well.
            To travel through these tubes, a person would normally start with a good leap. But to stay in the correct direction, a person should keep a loose hold of a small side rail. At the end of the tube a person would hold this rail more firmly. This grip will then turn the person round and so they would land on their feet at the end of the tube. This form of travel would also apply throughout the colony, which is not blessed with gravity. So in the construction area, there would also be several of these light rails to help people move around more easily.

I will now give the details of all the various facilities.


1)          The Revolving Residence

This residence would consist of cylinder revolving around its access tube. This cylinder would be 50 m long and 50 m wide. By my calculation, if one revolution takes 10 seconds, then this speed will provide an Earth-like gravity on the perimeter of the cylinder.
            Some people claim that this motion will make people sick. This is not my experience. I have studied this effect carefully both on the spinning walls (with the spinning wheel) at Lunar Park, and also when spinning on a high rope swing. A person becomes sick because of the confusing picture, when the person looks at the outside spinning world. But, if a person cannot see the outside world, then the centrifugal force seems be the same as gravity. (In the same way as Einstein predicted - a person cannot distinguish gravity and acceleration). In this revolving residence, its residents won't be able to see the outside world. So they shouldn't feel sick. There will be plenty of opportunities for the residents see the outside world in the rest of this large complex.


If you consider the liveable perimeter laid-out as a rectangle, then this area will be 50 m wide and 157 m long. As shown in the diagram, I put the residential units for humans at the two sides of the cylinder. Then I propose a park with grass, plants, trees and small animals in the middle. (But, of course, us humans will use this park extensively as well.)
If I say both human residences are 10 m wide, then this park will be 30 m wide.

The human residential area now consists of two long strips 157 m long and 10 m wide. I will divide both these strips into into 16 very large rooms. 15 of these rooms will be square 10 m by 10 m. One room will be slightly smaller - being only 10 m by 7 m. So there will be 32 large rooms in total.
            I will say that, of these 32 large rooms, 24 will be for the residential units, each holding between 20 and 25 people. The other 8 large rooms would be used for activities like: class-rooms, office rooms, work rooms and the meeting places for the clubs and societies of the colony etc. (If necessary the roofs of the large rooms could be used for these other activities as well.)

            It is not easy to house roughly 22 people in a 10 m by 10 m room. But I am very familiar with this situation myself and I like it very much. This situation occurs all the time in climbing huts and barns, and I think it is wonderful. It is very social and friendly. There is certainly no possibility of a person getting lonely. The only time I haven't liked this situation was when such a hut was empty. Then it was awfully lonely and creepy. I preferred to go out and sleep in a tent when this happened.

            Now I know most people claim they must have a room to themselves. But the evidence is that people, who live in close communities, are happier than people who isolate themselves. So many people like to go on holidays on ships, squashed up with many other people, because it gives everyone a much better social life.
            Clearly families would all go and all live together in one residential room. If people want a little privacy, I suggest that there be some light little tents available. Then people or couples could take these tents into the park and enjoy their privacy there. My preferred organisation for such a large room is shown in the diagrams.
            The back wall of the room (10 m long) would be for toilets, showers, washing machines, driers and sinks etc. Finally the item marked "C" is a "Cooler Cubicle", as discussed in my "Our Hamlets" webpage. Here this cubicle would mostly be used for children who are behaving badly.


            The two-side walls would contain large hooks. Each member would have one large hook and from this they would hang all their personal possessions. At the back of the hook, they would hang their bedding (including a small mattress). In my webpage "An Easy-to-Make, Complete, Floor Bedding System" I describe such a bed. It is a very comfortable bed package and the bedding system all falls into place when it hung from the bottom (on the hook). So beds will never need to be made. So all the bedding will look tidy and will always be ready for use. (Two of these beds can be put next to each other and then be used as a double bed.)
            Then the person's clothes and other items will be hung in front of this bedding on coat-hangers. (Some of these items would be bags containing smaller items.) I have lived like this myself for extended periods of my life - and it was fine. Such a system certainly prevents anyone from collecting too much junk – and this is our major problem in this current world.
            The front wall would be all glass. So all people would always be able to look out at our wonderful park, which would be our pride and joy. Out alone in space, it would be terribly important for all people to always feel that they were still part of our great web of life.
            In the centre of this large room would be a large stove, around which all people could gather round and all the cooking and serving would be done.
            All people would sleep and live on the floor. There would be no tables or chairs here at all.

I am sure that most people will be horrified at such arrangement. Let me argue my case in terms of the following seven points.

a)          Just a few centuries ago, this is how all us humans used to live. And these people lived and thrived under these circumstances – otherwise we wouldn't be here now.

b)          This floor living situation is much better for our children. So our children can always be in physical contact with us. Then our children can play and wander wherever they like - they can't fall down and hurt themselves anywhere.

c)          This is a very egalitarian form of living. So everyone will only use the space they need and no one will have a chance show off their personal possessions (unless they wear them or are using them).
d)          This form of living will require very little cleaning. The floor will need to be swept several times a day (and occasionally mopped). But this will be easy because there will be no furniture (or any other objects) to get in the way.

e)          If people do want to use tables and chairs, then they can be situated on the roof. Children can be prevented from coming up here by not letting the hand rungs of the ladders go down too far. (The stairs up to the access tubes (leading to the other facilities) would naturally lead up from these roofs. So working people would come and go across this roof very often.) This roof will not be like a normal roof and so be supported from the ground. Instead it will support itself by using its own longways tensile strength (like the floor). But when a person would walk on this floor, then it will feel slightly springy. (This is shown in the general picture.)

f)          This arrangement will minimise the size of our living area. This is terribly important because the floor structure must be strong enough to support the outwards tension caused by the centrifugal force. This force limits the diameter of such cylinders to about 5,000 m (5 km). For a 50 m diameter cylinder, this force is fairly minor. But this force must still be considered carefully.

g)          Finally and most importantly, this structure of living will support good government. Democracy suffers from a problem I refer to as the "Lack of Incentive to Vote Well". (I discuss this problem in my webpage "Known Mathematical Results".) The easiest and best way of overcoming this problem is to support several levels of government. So in my Town-Sate I had 3 levels of government. For 500 people it is best if there are two levels of government. And these residential units will automatically supply the colony with a first level of government.
           So each residential unit will govern its own internal affairs. So I suggest that they elect their own: Agricultural Officer, Home Duties Officer, Membership Officer and Representative. Then the whole colony will be run by a house of 24 representatives (and these representatives will elect all the many officers, who will run the many technical activities associated of this very complex colony).
          So there are many good reasons to support this dense living arrangement. I argue this case for a more dense form of living more fully in my "The Wonder Plant – novel".



Our park would support all the many kinds flora and fauna, which we humans like to see around. However some of this fauna would be cats and dogs for us to play with. Also some of the fauna could be chooks and rabbits, which we would occasionally eat – there is nothing wrong with this.

          We humans would of course use this park for exercise and games. So the park must contain a small swimming pool and playing fields. And most people would walk or run around the park many times a day. Besides this, the park should have a good surface for a good full community dance every Saturday night. This same spot should also be the venue of all the full colony meetings. Only unit representatives and officers should have the right to speak at such full meetings - but all people should be able to watch and hear what is going on.
          These very close living arrangements will ensure that all people will feel that they are very much an integral part of their total community. This will be good – and this communal situation doesn't happen much in our current world.

Finally I need to come up with an estimate of the weight of this residence per person.
          The floor area is 157x50 = 7,850 m2
          The side walls area is 2xPIx252 = 3,925 m2
          The volume of air is 50xPIx252 = 98,125 m3
I will now estimate –
The floor weight + soil + flora etc as 400 kilos per m2;
The weight of the side walls as 50 kilos per m2;
The weight of the air as 1.0 kilo per m3.
          This give a total mass of
400x7850 + 50x3925 + 98125 = 3,434,375 kilos
So the residence will weigh 3,434 tonnes. I will also allow 1 tonne per person for their body weight, personal possessions and share of amenities.
          This then gives us a total weight of 3,934 tonnes. This gives 8 tonnes per person. This seems reasonavble to me.


2)        Agricultural Facilities

It is very hard to know how crops will grow without gravity. But aquatic life is mostly unaffected by gravity. So aquatic life should be easier to produce in space.
          I would imagine that the direct sunlight, which we would have in space, could be too strong for normal plants. So the light could burn them. The solution, which I suggest in my diagram, is that the plants be arranged so that the sunlight hits the plants obliquely. And, besides this, a slight wind will be introduced to this garden. Then the leaves would move around a little. So the situation then would be a little like what happens in the canopy of a forest. But it will take some time to work out what the best arrangement could be.

          This intensity of light would be less of a problem when growing algae. Algae naturally move around and so they automatically share the sunlight. But a certain amount of turbulence might be useful to help this movement. (This could be done when the oxygen is being added.) The problem with this form of life is that water weighs a lot. If we can keep our depth of water to less than 20 cm then this form of life is OK. But if we need much more than this amount of water then this becomes a problem. I certainly don't know the answer.

Now I face the difficult task of estimating how big an area we will need and what it could weight. This is going to be difficult.
          I usually say that a person needs a kilo of grain a day to sustain them. And a square meter can grow a kilo of grain in a growing season. So if our growing season is 120 days (a normal time), then we would need 120 m2 of sun-lit area to sustain one person in space. Compared with the 16 m2 of floor space this is a lot. (Although this is very small in comparison to the amount of land we use on Earth.)
          But we could use less. A kilo of dry grain contains 15 MJ of energy. The recommended limits for humans are between 6 MJ and 9 MJ. So this means we could halve this area to 60 m2.
          Also the energy density of our light in space would be at least twice as much as we receive on Earth. (This is why I have arranged my oblique system.) So we can halve this area estimate again to 30 m2.
          And besides this, our Algae ponds will produce much higher growth rates and are capable of a great variety of food types. (Apparently these clever little primitive algae can produce almost any kind of complex organic molecule they like. This is what my friend Jack Pettigrew FRS tells me. So he should know.)
          So with this addition, I think the best assumption we can make is that our agricultural area ought to be 30 m2 per person.

All this organic stuff must be recycled. But, when doing this, we can grow some healthy meal-worms. So we can still enjoy some good genuine animal protein.

But all these growing areas will now be rather complex affairs. I think we should allow one tonne per m2. So the weight of all our food-growing facilities may be 30 tonnes per person.




3)        Energy Facilities

PV panels have been extensively used in space for many years to give energy to Space Stations. We will do the same. So this should be no problem.
          A large amount of energy will be used in the conversion process of changing raw materials to the required materials. But most of this energy is just used to raise the temperature of the raw material to a very high temperature (so it melts). And a high temperature can be more easily obtained by reflecting the sun's rays to the focus point of a parabolic mirror. So our raw material should be taken here, heated up, and then taken back and converted to a more usable form.
          Of course I don't know much about these conversion processes. (Later this raw material could be coming from the moon.)

The weight of PV panels and reflective material is reasonably light. So the total weight of these facilities will not be greater then 500 tonnes. So this will not be greater than 1 tonne per person.




4)        The Construction Cylinder

The prime purpose of this construction facility will be to make the large components, which will be used to extend the colony. (Or possibly to duplicate the colony.) So this cylinder needs to be quite large. The cylinder must contain an atmosphere to make life easier for our workers. But it is best to have no gravity here because then all these large objects can be moved around very easily. The shape of the facility should still be cylindrical to be able to support the air pressure. (I haven't talked about the nature of the air in this colony yet. I would imagine it will save weight (and pressure), if this air contains a much higher proportion of oxygen.)

Firstly this area region must also contain a fleet of space vehicles in the form of - capsules, rockets and material movers.
          The rockets and capsules would allow people to come and go to the Earth (or possibly the moon). How often people should travel to the colony and back to Earth is debatable. I think people should stay in the Space Colony for at least a year, so that they have enough time to become an integral part of the life in the Colony. Many people might wish to enjoy this special year experience. When everything is working well, I don't think such trips will be too expensive. So most of the keen members of our Town-State should be able to enjoy this very unique experience.
The material movers will hopefully eventually provide the Colony with raw materials from the Moon.
          These vehicles must be unloaded, loaded and repaired in this region. And finally new similar vehicles must be constructed in this region. They will enter and leave via the large airlock.


The things that this construction region will be making are, of course, all the objects that this colony is made of.
          But first we must make the materials, which will make these objects. The raw material most commonly used will be the old rockets parked outside. (In my picture I show these rockets at the bottom of the picture. This is a mistake. The old rockets should be outside this construction area. But I drew this picture before I realised that we would be using these old rockets.) Later we might be using material obtained from the moon. I am afraid that I don't know too much about this subject. The strongest materials are usually composites made with various glass or carbon fibres and glue. So we should mostly be using such composites.
          These materials will then be used to make all the components that make up this colony (mostly the various walls). But glass or clear plastic will be needed for windows and in the agricultural area. Then these components will be joined together to make the large elements of the colony's structures (the size of these elements will unfortunately be limited by the size of the airlock). Finally these elements will be taken outside through the airlock into space and added to the current buildings structures. Thus the facilities of the colony will be slowly extended (or even duplicated completely).

Also we must make really hard items here like - PV panels, computers and communication facilities. This will take a long time master – but it must be done if the colony wants to become truly independent.


I shall assume that the mass of this structure will be similar to the mass of our residence structure. This construction cylinder will be significantly bigger - but then its exterior can be lighter because it will not have to deal with the centrifugal forces.
So this structure and its contents should weigh about 8 tonnes per person.


5)        External Crawlers

When we need to check and repair our houses, then we need to go outside and often use a ladder to do these tasks. And when we need to extend our house, then we need to hire a huge crane to do the job (or use scaffolding). When people do these tasks on International Space Station, then people have to put on complex space suits and then a huge arm like crane moves them around.
          I think we could do these extremely important tasks more easily and safely by using a team of little "external crawlers". This is how my system could work.

I first propose that, on the outside surface of the colony, there should be a good knob on every square meter of this external surface. A small mechanical hand could grab these knobs very easily and securely.
          A crawler would be a small vehicle with four flexible arms. On the end of each arm there would be one of these mechanical hands, which could grab hold of one of these knobs. The crawler would hold one or two people who can control its operation. But a small computer could probably do a

better job of directing the arms and hands of this crawler. This computer would have a plan of where all the knobs are. So, if the operator points in the correct direction, then the computer would do all the mechanical tasks of directing all the arms and hand as to which knob to grab next. So the crawler would slowly crawl round the outside surface of the colony as directed by the operator in complete safety.
          On the bottom of the crawler, there would a good window and light, which would allow an operator to inspect the surface very well. But there would also be a variety of tools to repair any damage or flaws. The operator could also insert his hands into external gloves to do any work by hand. So this system would allow us to carry out inspections and do minor repairs to the outside surface of the colony.

To add an extra element to our structure, we will need to make a larger crawler. At the bottom this bigger crawler will have more arms and hands. On top, this crawler will have a large flexible arm with a large flexible hand, which can hold four knobs. This large arm will attach to this new element by holding four of its knobs. The crawler will slowly move holding this new element above it. (There will be no gravity to worry about so the forces will be quite weak.) The arm will slowly place the element in the correct place. Many normal crawlers would help in this process. So all normal extensions can be carried out in a sensible manner.
          The hardest task of course would be to extend either of the cylinders. It would possible to devise a system by which the length of these cylinders could be extended. But often it would be better to simply build new larger cylinders.

So our colony could be mended and extended reasonably efficiently.

          The Total Mass of the Colony

The masses I have estimated already (in tonnes) are:
                                                  Per person                     Total
Residential cylinder                               8                     4,000
Food Growth facilities                          30                   15,000
Energy facilities                                    1                        500
Construction facilities                            8                     4,000
I haven't estimated the mass of the connecting tubes yet. I will estimate this at 1 tonne per meter. And there are less then 500 meters. So this gives
Connecting tubes                                  1                         500
This gives
Total Mass                                         48                     24,000

These figures of course are very rough. Thus construction facilities could easily be twice as high as this. But then the Food Growth facilities could be half as much (if I allowed half a tonne per m2 – which is possible). My "per person" figure is similar to that experienced in the International Space Station. For simplicity I will round the figures up to:
Total Mass 50 25,000

So this is the nature of the Space Colony that I am considering. It is hard to suggest a practical solution with no experience in this complex issue at all.

You can now read about "Long-Term Safety and Human Goals".


You might now also like to look back at:

either my "Home Page" (which introduces this whole website and lists all my webpages),

or "The Ultimate Ascent" (which introduces these webpages),

or "A Path to Create a Full Space Colony", (which introduces the coming webpages in more detail).


Updated on 9/11/2016.