Appendix B - Population

Population – Size

(ref. 37, 66, 67)

There have been various estimations of the population necessary for a self-sufficient community on board a space settlement.  Most maintain that a very large population, usually 200,000-300,000 people, is required.  When judging this figure, it should be noted that that is also the figure suggested by ’75 Summer Study for a self-sufficient station, “…cities need populations of 100,000 to 200,000 in order to provide an adequate range of commercial service.  Moreover, populations of 200,00 to 500,000 are required to support broadly based manufacturing activity…Economies of scale for communities suggest an optimal size well above that of the early settlement in space (10,000)”.  We believe however, that the suggested size for an early settlement is quite adequate for a permanent manufacturing and research community.  

This figure takes into account the number of people that a space station would need to function economically, while keeping the size of the station within realistic proportions.  The settlement will possibly not benefit to the full extent from some economies of scale e.g. - it would not be profitable to have a paper industry on board.  However, the small size of the community should also make it more productive in some ways.  The theory of internal diseconomies of scale suggests that the smaller the firm (or in our case, settlement) the more responsible people will feel for their actions, for example, in a large firm employees are more likely to steal from the stockroom, or take the stationary from their desk.  In a small community, people will participate more and feel personally responsible for the well being of the settlement and everyone aboard, and so be more productive.  The number chosen also takes into account the decreasing number of people required for many tasks in industry and services that can now be carried out by machine.

Population – Composition

The initial population of the space station will be very different from that when it is fully operational.  The first people there will be those who will construct the station.  Much of this work will not be in a shirtsleeve environment, and the accommodation will not be comfortable.  The population will therefore be similar in make up to that of say an oilrig, or one of the research facilities in the Antarctic.  Studies of workers in these environments have shown that people choose to work in these extreme conditions for three main reasons:

1.   Financial gain - this will not be applicable as the wages will be set at a rate that will not influence those who will ‘put up with it’ for the sake of good money.

2.   A sense of adventure - working in harsh conditions provides a challenge

3.   Living conditions - some people like living and working in an isolated environment, and so choose a job there to ‘get away from it all’.

Although some workers will wish to remain and become the first settlers of the station, most will return to Earth when construction is finished.  For those who wish to remain, there will be jobs available in construction of the SPSs and the maintenance of the station.

At this point, the population will change to include those with other skills to offer.  The people and families who come aboard will be carefully selected to ensure that all have a valuable contribution to make to the community.  As a ‘pioneer’ station, the majority of the population will be quite young, probably within the 25-40 age group.

Some workers may choose to bring their families with them.  However, it remains to be researched whether young children would be adversely affected be the rigours of space travel. For this community to be permanent, it must regenerate, and no doubt people aboard will form couples and have children just like on Earth.  The group throughout the lifetime of the settlement will remain relatively static.  However, the initial condition of 8,000 people who do not know each other coming together to form a ‘new community’ provides an entirely new situation. When attempting to estimate the population growth, the majority of long-term relationships would form within three to five years of the official ‘opening’ of the station.  While not all couples will choose to have or raise a family on DL4, it seems logical to assume that, on those grounds, population growth would be at a maximum within the first 5 years.  After rapid initial growth, the population will continue to increase, but at a much slower rate.  To account for this, the initial population will need to be about 8,000, to allow for growth of 1.5 % ±0.5 % per year, and a transient population of 250-300.

The bias in favour of males in the 25-44 years group allows for construction workers who will remain behind to live on the station.  At present, few females choose to participate in this industry, and there seems to be no reason why this would change in the future.

table (a) -  Initial population (estimated composition)

Taking this into account, the settlement is left with the following approximate population make-up, once it is fully operational, and the population has grown to the ideal level of just under 10,000 (9,393).  (Some of the children brought to the settlement, and the first of those born on the station may have returned to Earth to attend university etc.)

table (b) - Population, 20 years after initial habitation

Making the population static

There is room for a minimal amount of expansion within the station to cater for an increasing population, as the cost of living, carrying out research, or industry falls, and as people are born.  However, ideally population would be kept as close to static as possible.  To give an idea of how difficult this task will be, we have attempted to outline the factors that will serve to increase and decrease the population.

Factors increasing:

Birth rate: 1% per year

The figure for the birth rate is based on the average of North America and Europe (1.4% per year 1985-90), reduced to take into account the reduced number of couples on the station.

New members:

This figure is one of the few that can be directly controlled, to guard against a population overload, without directly interfering with the right of existing residents to exercise their free will. If the numbers who are seeking to become residents of the station, or conduct industry or research on board increase sufficiently, the construction of a further settlement will then be warranted.

Factors decreasing:

Death:

The death rate will be low, due to the low numbers of elderly, the strict control of disease-causing viruses and bacteria, the health benefits of the diet, and the size of the community (a sense of collective responsibility will mean that people will ‘look out’ for one another and violent crime will be low).  The residents of DaedalusaL4 will also have access to state-of-the-art medical facilities, as good, if not better than hospitals on Earth. When these factors combine, they far outweigh those that could be possible health risks, e.g. high stress levels, radiation etc.

Departure:

1.       Retirement

When residents reach retirement age, they will have the option of returning to Earth. This will probably be the preferred option of many, as life, although comfortable on DL4, is primarily concerned with work and manufacturing.  It is not the ideal ‘retirement destination’.  ‘Normal’ gravity levels, the healthy control of bacteria and micro-organisms, and vaccinations will mean that the residents will not suffer health deterioration in those respects that would otherwise prevent them from returning to Earth.  If the birth rate is lower than expected, then those that really want to may have the opportunity to spend their last years on the station as educators, advisors or honoured guests.

2.       Other reasons

The isolation that some people will experience, living in an enclosed environment with a relatively small population, will inevitably mean that some people will be unhappy there.  There will be no huge monetary gain for individuals working on the station, so this will eliminate one group of those people who go to work in harsh conditions on Earth and do not acclimatise.  The thorough training and preparation required before going to the station will hopefully eliminate those who would not be happy or fit-in.  Despite this, there will be people who are there for a short while who will return. They may return of their own free will or they may be returned as a form of punishment.

If all goes according to plan, the permanent population should level out to the following approximate composition:

table (c) – composition of permanent population

The male : female ratio should even out over the lifetime of the station, although a perfect 1:1 ratio is highly unlikely.

The total of all categories is 9,800.  This gives a margin of error, and although this will be a permanent settlement, there will be a transient population of, for example, research scientists and eventually tourists.  The station will be capable of comfortably supporting 10,000 people without requiring construction of further living space.  This means that even if the population increases dramatically for an unexpected reason, there would be no overcrowding and there would not be an undue strain on resources.  It also does not pressure families into having a set number of children.  It gives them a greater sense of freedom, and will help to contribute to the idea of ‘living’ instead of ‘living on a space station’.

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