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by Ray R. Collins
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A biosphere is defined as an ecologically closed unit which recycles everything but energy. This paper addresses the problems and outlines the work which needs to be done to design and build a functional biosphere capable of supporting one or two people. The overall objective is to develop and demonstrate the biological support systems which will one day be necessary to colonize space. This experiment is qualitative and not quantitative in nature.
In general this means that energy may be used extravagantly to force the system to respond in the desired fashion. The interactions between ecological niches in the closed ecosystem are expected to be very complex. It is uncertain at this stage if it is even possible to maintain a balanced ecosystem. Due to the number of variables it is difficult, if not impossible, to get meaningful results from computer simulation. Therefore it becomes necessary to build an operating system and then, by trial and error, see if it can be balanced.
The general procedure to be followed is a gradual build-up of ecosystems which will ultimately be integrated into the closed system. No input of material is permitted to the system once it is sealed, and it must remain isolated until the termination of the experiment. Current blueprints show a dome about 10 meters in diameter and 5 meters in height (see Appendix I). The proposed building will be made of concrete, 15-30 cm thick, to provide the strength needed to maintain pressure as high as 14 psi. The center area will be the living area and the remainder will be divided into garden space, animal habitat, recycling and any other needed functions.
The basic diet is to be vegetarian, with a small number of fish and possibly eggs, rabbits and quail providing protein to the diet. Living space will be minimal and maximal crop intensity will be needed. This is due in part to the necessity of keeping the weight of the biosphere down (for easier transport to space) and in part due to the expected difficulties in sealing the biosphere--the smaller the structure the less chance of leaks.
While it is not the intention of this project to construct a nuclear survival shelter the only thing lacking will be a power source. If one was provided it should be unnecessary to leave the biosphere for any reason for as long as the power lasted. Since it is being constructed in an arctic region it would have adequate insulation against all but the most severe nuclear winter. While no definite timetable has been set it is hoped that by the fall of 1991 construction will be complete and the biosphere will be ready to begin start-up operations. It is expected to take as long as 2 years to obtain the desired balance in the various water, air and nutrient cycles. Then the biosphere will be sealed and a person (or persons, if it is felt the biosphere will support them) will remain inside for an entire year. This schedule is very uncertain and at best represents an educated guess as to how long it will take to build the biosphere and put it into operation.
The purpose of this project, then, is to build a working ecosystem that is capable of sustaining human life without any input except energy and which could be transported into space and continue to function as a viable ecosystem (barring the effects of the lack of gravity).Unlimited energy resources will be assumed. The problem being addressed is the cycling of matter within the biosphere and keeping it balanced. Design therefore disregards energy conserving measures, though where practical they will be employed.
Ray R. Collins
Please note that this is a version of the biosphere paper specifically reworked for HTML and, while is mostly complete, lacks appendices, and a table of contents.
For almost 10 years I have been investigating the possibilities and problems of constructing a biosphere--a biologically closed system capable of supporting one or more people. To further my goal of helping in the eventual settlement of space I have started the International Space Exploration and Colonization Co. (ISECCo). The first project of ISECCo is to construct the biosphere outlined in this paper.
Biologically closed systems have not had much research done on them; certainly not enough to advance the technology to the point where it is feasible to build them in space. I feel that this is an important issue that urgently needs to be addressed. With the current costs of getting material into space it makes much more sense to 'grow your own' than to import from earth. The cost of building a small, airtight structure is not prohibitive. Once a structure is built the balancing of interior systems will merely take time and experimentation.
With the help of a few friends I believe that I am capable of constructing a working biosphere. Even should I fail to make the life cycles balance I will gain valuable insight into the processes involved. The USSR has built working biospheres of sorts; they have yet to achieve a good balance which can be sustained for long periods of time and often their chief food is algae, which is not only monotonous but may well lack vital nutrients. I hope to build a true biosphere, one which is completely cyclic in all the nutrients and elements. I hope to obtain a PH.D. from the five or more years I expect to have spent researching, building and operating the biosphere.
A number of people have generously contributed ideas, editing and expertise to this paper. Foremost among them I would like to express my gratitude to my parents, Florence and Dick Collins, who spent many hours reviewing both my grammar and my logic; Lynn and Karen Zuelke, Pete Mayo and Matt Jones all reviewed my ideas and made many valuable suggestions.
This section of the paper outlines the research needed before construction can begin, explores the possibilities, and tries to limit the problems in the construction and operation of a biosphere.
The physical structures involved and the less well explored areas of nutrient and air cycling and the inevitable human problems of living within a confining space for prolonged periods all need study. Many of the questions will probably not be satisfactorily answered prior to the actual construction and operation of the biosphere. It is hoped, however, that the research will provide solid answers to the questions of biosphere size and cost, and an approximate timetable.
Structure research will determine such important elements as cost, materials and size. Engineering expertise will be required to assure an effective design. The following paragraphs discuss the topics that need further study.
The exterior shell needs to be strong enough to withstand considerable pressure due to the internal pressurization (preferably to +10 psi, though +1 psi--above ambient--could suffice) used to increase plant productivity and to verify an airtight seal.
The possibility of submerging or burying the biosphere needs to be researched. While there are advantages to submerging the biosphere (e.g. proof of airtightness) its buoyancy will probably be prohibitive. Burying it would turn it into an effective bomb shelter and also minimize the external temperature variations. The advantages and disadvantages of building underground need to be explored in detail.
An adequate type of insulation must be determined. The biosphere needs to be insulated from the cold in the winter, yet must not overheat whenever there is an excess of energy from all the lights and electrical equipment.
The interior shell is primarily concerned with an airtight seal. Some possibilities are Fiberglas, rubber cloth, paints and tars. Each of these options (and any others found) needs to be investigated to determine cost, effectiveness and environmental interaction (i.e. deterioration, health effects, and odors).
The internal structure will consist of the framework upon which the plants are grown and will determine the general outlines of the living quarters, fish and poultry areas as well as locations of such things as dehumidifiers, water tanks and waste management areas, etc.
The most space-efficient plan needs to be determined for each of these, and for the airlock and such things as emergency escapes, power switches, plumbing and wiring all need to be designed.
The goal is to build a biosphere that is capable of supporting 2-3 people. Feasibility will be tested with only one occupant. Once it has proven that it can support a single inhabitant, others may join to demonstrate its maximum capacity. However the initial living space and support systems will be designed for a single occupant.
The gardening area, based on an estimated 75 square meters per person[A1], will cover 150 square meters. With multiple layers of gardens, and areas for "livestock", waste management, and living space, the diameter of the biosphere will be about 10 meters. This assumes 2 floors, with each gardening area on a floor being further divided into levels; the height of each level is determined by the crop to be grown.
The cost of the biosphere is of primary concern if it is to be privately financed. If grants are obtained cost will be of less concern than quality. In any case, a reasonable estimate of the cost of the biosphere is necessary before planning can proceed very far or a definite time frame be set.
Ecology is the most difficult area to research yet it is the most vital portion of the biosphere. Unfortunately very little information exists that directly relates to biospheres, for one has never been successfully designed that was capable of supporting man indefinitely.
Some general questions to be answered include:
Given the answers to the above questions it should be possible to calculate the quantity of decaying biomass to be maintained, the general garden area and the amount of carbon and oxygen surpluses to be stored in order to maintain a safety margin.
Questions concerning plant nutrients follow the same pattern as those concerning carbon and oxygen balances. With these answers it should be possible to determine the minimum decaying biomass needed to produce the necessary nutrients. It may not be possible to determine this from the literature, however, and may have to be determined experimentally after the biosphere is in operation.
Other questions concerning general cycling of water and energy, and the paths of food and nutrient flow between plant, fish, bird and man need to be addressed. Many of these may also have to be answered after the biosphere is in operation.
The fish and poultry are expected to subsist on garden by-products. Since there is not expected to be enough of this material to support large numbers of animals the diet will be mostly vegetarian.
The biosphere must produce a fixed number of calories to keep each human inhabitant alive. Fish and poultry will provide a portion of these calories. Since they are expected to survive on plant remains the calories needed by the human inhabitant(s) may be used to determine calorie production needed. Given the desired ratios of crops (based on nutritional needs) to be produced and their caloric output an area for the garden can be calculated.
Plants are the primary source of energy for higher organisms. The biosphere's plants will occupy most of the space, with everything else crowded around them. Study of what kinds of plants to use centers on calorie production/unit area (i.e. efficiency) and nutrient content. Palatability (unfortunately) takes a back seat in these considerations.
An integration of the best variables for overall crop production will not be easy and a fair amount of experimentation will probably be required. Some of the questions about each crop include:
Food plants can be classified as vegetables, fruits and starches. While research into every variety of plant food can not be done in detail an attempt will be made to identify those plants whose products are of interest in terms of survivability, production, nutrient requirements and biodegradation. (See Appendix II for a partial list of plants to be investigated.)
Most of the necessary research into fish productivity has been done by the University of Arizona Environmental Research Lab[A2] in connection with the Biosphere II project (a Biosphere being built near Tucson, Arizona by Space Biosphere Ventures[A3]). Their data indicates that Tilapia species, which are African cichlids, have the most promise as a biosphere protein source.
The purpose of having poultry is to provide a source of protein, both from eggs and from meat. There are a number of different problems involved with poultry production which include proper food production, sanitation and odor. It may not be feasible to include poultry in a biosphere of this size. They will be tried, however, and if they are not viable they will be excluded.
Chickens may prove a little large; in order to maintain a viable population the food requirements may be more than the biosphere can support. A smaller bird, e.g. quail, may be a better alternative.
The quantity and quality of food required for each possible species must be determined, as well as their food to protein production ratios.
The physical systems of the biosphere are responsible for forced cycling of the ecological systems and the maintenance systems (e.g. heating). They deal with ecological management, power supply, temperature control and domestic life (such things as video systems, airlock and cooking and cleaning systems). The major ecological systems are water, nutrient, and air cycling, and waste management. All these various systems need to be integrated for the smooth operation of the biosphere.
Research is needed to determine the amount of power required, the necessary reserve, the minimum acceptable level of power and the greatest duration expected for any power outage, in order to determine the size power plant required for basic back-up and the number of batteries needed to maintain a minimum level should the back-up generator also fail. Wiring, fusing and automatic and remote control (since the generator can not be located inside the biosphere) systems also need to be designed to tie all three systems together safely.
The temperature control system needs to provide heating in winter. Research is needed to determine if cooling in summer will be necessary; power consumption of all the electrical equipment, compared to the rate at which heat will be lost through the walls, should determine if a cooling system is necessary. [Comment added 12-95]
The heating and cooling equipment is expected to be located outside the biosphere due to space considerations. Therefore the heating (and cooling, if needed) will probably be via water radiators through which either hot or cold water will be circulated. This will make it quite easy to pipe the heated/cooled water through the wall; most other forms of heat require exchange of air, which is prohibited in the biosphere. Electric heat may be considered but due to the present electrical costs and the fact a second system would be needed for cooling it is doubtful it would prove efficient. More study is needed to determine the kind of heating and cooling equipment required.
The heating and cooling capabilities used to overcome outside temperature fluctuations may also be needed to provide cooling (e.g. for ripening wheat?) in certain areas of the biosphere and extra heating in others (e.g. hot house fruits.) Separating the hotter and cooler areas could be a problem and it may be necessary to leave the entire biosphere at a single temperature. Cold spots which could be a problem in winter) must be avoided or they could damage the more sensitive plants. The temperature requirements of the plants need to be explored before a final heating arrangement can be decided upon.
Cooking will be done with electricity to minimize the impact upon biosphere ecology. While it would be possible to ferment plant and animal wastes to produce methane to cook with odors generated by the decaying matter and the large colonies of microbes necessary might make it both unpleasant and unsafe. This may be a good area to explore at some time in the future, however.
Making soap would probably require more time and material than would be available. This should not be much of a problem since there are few, if any, foods which will be greasy and thus require the cutting power of soap. Sand is the alternative; it can be re-used almost indefinitely when kept clean by rinsing. Due to the lack of facilities (not to mention soap) human hygiene may be a little more difficult. Soap-less sponge baths seem the option; no shower or tub will be provided unless their excessive water and space demands can be met.
The airlock is outside the biosphere proper to allow for more room and provide an adequate storage for items only needed when going outside the biosphere. Current design calls for the airlock to be a simple water barrier through which you pass to enter or leave the biosphere. This barrier will also deter passage of microbes--by adding a sterilizing compound to the water--and insects as well as air. To minimize the exchange of gasses through the water a second airtight door just prior to entering the biosphere will be needed. If it is shown that this system will allow for an unacceptable amount of gas exchange then another system will be devised. Disinfectants for the water need to be investigated.
Toilet facilities are particularly troublesome. Urine can be added to the nutrient solution for the plants but solid waste must be degraded in some fashion or another. Pressure "cooking" or biochemical degradation are a couple of possibilities. This needs to be explored, as does the more mundane problem of how to clean oneself since toilet paper is not allowed to be imported.
Ecological systems are what the biosphere is all about. The systems that are needed to drive the ecology are not well understood and a great deal of experimentation will be needed before the right combination of microbial, plant and animal life and their support systems is discovered. It is possible, however, to foresee the major systems needed. Subsystems will be developed as the biosphere is brought into operation and they become needed. Things are going to be kept as simple as possible to minimize the number of variables. The basic ecological systems are discussed below.
Air recycling is probably what most people think of when they think about a totally enclosed space like the biosphere. However it should not pose greater problems than any other system; once the biomass is balanced between plant production, animal consumption and waste degradation, the air supply should follow into balance. The problems with air cycling will probably come from short-term cycles as elements get temporarily 'stored' in the form of plant or animal matter. Even daily cycles may pose a problem since the human will be active, using more oxygen, during the day. Methods of storing and/or locking up gasses need to be explored.
Research is needed into the following areas:
Water recycling should be fairly simple. Fresh water will be obtained from the de-humidifiers and most waste waters can be used as fertilizer. Any which can't may be pressure cooked to the point of complete biodegradation, or some method of microbial degradation can be utilized.
The biggest question in water circulation is how much water will be released into the air from plant and animal respiration. This will determine the size of de-humidifier needed, and if there will be an adequate amount of fresh water.
Most of the rest of the water recycling system research deals with designing the plumbing and pumps, and determining locations to which water must be routed. An extensive layout of pipes will probably be needed if a hydroponic system of gardening is used, and much of this can not be designed until the amounts and types of plants are selected.
This is one of the most complicated systems to be designed. However, once some of the basic questions on nutrient cycling are answered, it may be possible to answer the rest after the biosphere is in operation. Some of the more pressing concerns:
Odor and detrimental microbial populations are easily dealt with if one has access to modern chemicals but when locked in a self-contained environment they can pose problems.
Waste could be completely destroyed by oxidizing it under high pressure and temperature, but this could release detrimental gasses (something that needs to be investigated) and may destroy nutrients which plants need.
The alternative solution is microbial breakdown. This could produce odorous waste gasses but it may be possible to minimize them to an acceptable level. Plant respiration will help remove many of the undesirable gasses from the air and there may be other methods of dealing with them. The literature should have quite a bit of information dealing with waste products and this needs to be researched carefully.
The light level will be that at which each type of plant grows the fastest. This problem is exacerbated by the fact some plants require a dark period to complete some biochemical cycles. The lighting requirements should be determined for each crop, if possible.
Spectrum also needs to be considered and an average selected at which the plants will perform best.
Great care will be needed to maintain a steady flow of foods and gasses from the garden. Too much will cause a decline in the carbon dioxide, too little a decline in the oxygen. Once the crops have been determined a careful planting schedule needs to be worked out to prevent bumper quantities or lean times. A certain amount of over-planting should be done to allow for seedling mortality, etc. Any extra plants can be clipped when crop survival is assured.
Seed production needs to be investigated and those plants in which it will be a problem will be excluded. Synthetic seeds may be the answer to the problem of seed generation. The generation of cloned crops seems be ideal for this application, and while it may not be possible to utilize in this biosphere it might be the best method of seed production for any future space colony based on a totally enclosed ecology[A4]. Pollination needs to be investigated. Most plants will have to be pollinated by hand, and this will require collecting and storing pollen.
While construction of the biosphere does not directly deal with the ecology, it is an integral part of creating a working unit. Any pieces of the ecosystem left out during the design and construction phases of the biosphere project would have to be fitted in later at great expense and effort. Therefore every effort will be made to assure the completeness of the plans prior to beginning construction.
The ideas dealing with construction presented in this section are far from complete. They merely show what is currently thought to be the best way to build the biosphere. These ideas will undoubtedly change as research progresses. They are presented here to help solidify plans and allow for comments and criticisms.
Unless the biosphere is to be submerged or buried below the ground-water table its location is unimportant [comment added 12-95]. If it might be used as a bomb shelter it may be necessary to seek a site away from any likely targets for nuclear strikes (e.g. Eielson Air Force Base).
This is only a minor concern, however, and it will be lightly weighed. A small piece of land is available in North Pole, just off Badger Road, which is acceptable if the biosphere is to be above ground and, with work, below ground (the water table is about 3 m below ground, and with an estimated biosphere height of 5 m this could pose problems if the structure is buried. Leaving a portion of the biosphere exposed may be the best solution to this problem.) If funding is obtained a larger lot may be considered. The property has the disadvantage of being located in one of the coldest areas of interior Alaska, which would complicate heating problems if the biosphere is located above ground. There is also the possibility of permafrost, which should be explored carefully, though with certain designs (e.g. wood/fiberglas) it would not be affected much.
This will consist of preparing the site for the biosphere. A driveway will need to be built and, if the biosphere is to be below ground, an excavation made [comment added 12-95]. If the biosphere is to be above ground the topsoil needs to be scraped away so that the foundation can be placed on a firm surface. The control building area needs similar preparation. If the attached control building is to be equipped with plumbing and other amenities a septic system will be needed.
Powerline access must be cleared and power applied for. A well needs to be drilled or a holding tank installed to provide water to the control building, airlock and heating system.
The exterior shell consists of five parts: foundation, floor, walls, roof and the entrances. The roof, walls and floor need to be completely airtight and strong enough to withstand considerable pressure in case it becomes desirable to pressurize the biosphere.
Two methods in which the ways these five systems might be constructed are outlined below. Different materials would require somewhat different methods. No matter what materials and methods are used the goal of the external shell is an airtight enclosure of about 320 cubic meters capable of being pressurized.
Frame construction is well suited to above-ground application. The disadvantage is the strength limitation, which would limit the pressurization. The primary advantages are ease of insulating, and simplicity of construction. Frame construction would require a cylinder slightly less than 10 meters in diameter and 4 meters high.
If the biosphere is built above ground the foundation would be constructed of cement block resting upon a concrete footer and would extend a total of 1.25 m below the surface. A modified system of concrete or timber pilings may also be considered. These pilings would extend to a depth of at least 2 meters. Either system would provide adequate support and eliminate frost heaving, a serious problem in interior Alaska.
Should the biosphere be buried a simple foundation of concrete would be all that would be required, since it would rest below the seasonal frost level.
The floor beams would be several times stronger than regular house beams to allow for pressurizing the biosphere, and the flooring boards would have to be extra sturdy. Then the sealer would be put directly upon the floor to provide the airtight seal. The floor will be insulated with 12" of Fiberglas insulation if above ground and 6" if below. For simplicity no cover (e.g. carpet) will be used over the sealer unless it is necessary to protect it from wear.
The walls would be constructed from 2x8 boards on a 1 foot (308 mm) spacing. If the biosphere is above ground the exterior sheathing would be T1-11 (plywood-like material), if below it would be treated plywood. Interior sheathing would be several layers of 1/4" plywood laminated with sealer to provide an airtight barrier. Extra attention would be paid to the floor/wall junction to assure an airtight seal. Insulation would be 8" of Fiberglas.
The roof would be similar to the floor. Extra strong rafters and several layers of boards would be used to insure sufficient strength. Sealer would be applied generously to the inside to make an airtight barrier, and the exterior would be similarly coated to keep water out of the insulation, which would be 12" of Fiberglas.
Extra attention should be paid to the roof/wall junction to assure sufficient strength for pressurization. Even with just 1 psi internal pressure the total pressure exerted upwards on the roof would be about 50 tons.
There will be 2 entrances: an escape hatch through the roof (for emergencies like fire), and a main entrance out through the control building. The main entrance opens out into an airlock (see below).
The roof entrance will also be a small airlock, probably made of a piece of pipe 75 cm in diameter with hatches at both ends. In the event of fire the occupant would get into the pipe, close the hatch behind him, equalize the pressure with the outside and then open the outer hatch to escape.
A cement structure would probably be limited to underground use due to the problems of insulating it. However it has an enormous advantage in strength. Due in part to this advantage it is currently the favored method for shell construction.
The cement floor would form its own foundation. The only thing that is needed is a smooth, packed surface.
The floor would be 5-6" of concrete with wire mesh embedded in it. A sealer would be applied directly to the cement to provide air-proofing.
The wall thickness' will depend upon the desired amount of pressurization and the soil load over them. A dome shape would be used to minimize surface area and maximize strength. Stryrofoam insulation may be embedded in the dirt outside the walls. The top of the biosphere will be 1-5 meters below the ground surface, which will provide considerable insulation by itself. The walls would be sealed in the same method as the floor, with special attention paid to the floor/wall junction.
Entrances would be the same as in the frame construction, except that the material may be concrete.
The interior shell provides internal support, and separates the various functional units in the biosphere--the living areas, animal areas and crop areas by floors--with walls and walk-ways. Space also needs to be set aside for such things as dehumidifiers, water tanks and waste management. A certain amount of internal strength may need to be added to allow for pressurization. If so this would be in the form of wires strung through the interior floor and walls at strategic points, connecting the exterior walls, roof and floor with an interior network.
A circular area of about 4 meters in diameter in the center of the biosphere will form the living and kitchen area. The walls between this room and the rest of the biosphere may be nothing more than a visqueen barrier, or even nothing at all. It will contain a stove, sink, short counter, small refrigerator, table, TV, video machine, hot water heater, cabinets, table, chairs and a small sofa.
A bedroom-den is immediately above the kitchen. Floor structure is probably going to be light and may be suspended from the ceiling rather than supported from below, to help counter-act pressurization.
A ladder will connect the two floors. Walls (if any) separating this area from the rest of the biosphere will be as above. This area will include a bed, desk, chair, bureau, computer area, and bookshelves.
The garden areas will occupy most of the biosphere, forming a ring around the core living area. Each garden area will be composed of multiple levels, the height of each level determined by the height of the crop being grown. Sturdy structures will be needed to support the weight of the root medium (be it soil or a hydroponic gravel bed), water and crops. Walk-ways will divide the garden area and provide easy access to the crops.
Poultry will be kept confined to a small area, probably on the first floor. Air will be evacuated from there through biological filters to help remove odors.
Fish will be kept in several large aquariums, probably located on the second floor (where it should be slightly warmer) above the poultry. Structural strengthening may be necessary to assure sufficient strength to support the aquariums.
Ecological management areas can be located in odd corners, though a few may require a significant amount of space. A gravity based water system is possible if the dehumidifiers and fresh water tanks are suspended from the ceiling. A good location for the dehumidifiers and water tanks will be over the desk and/or the bed, where there is unused space.
The waste water breakdown area will need either a large tank or a small area, depending on whether it is to be done via biological degradation or forced oxidation (autoclaving). In either case it will be located on the first floor, probably adjacent to the poultry cage.
Air purification will need several large containers (see section VI. D. in this chapter). Location is not particularly important, though input air should be from areas which are going to be particularly odorous, such as waste degradation and poultry.
Biodegradation of plant (and possibly animal) wastes will be done in vats by saturating them with water and incubating them. The vats will need to be aerated to reduce methane production. The resultant liquid will be used for the plant nutrient solution. Further degradation may be done by vats filled with wastes and earthworms. These systems will be located in spare nooks and crannies.
If earthworms are raised beds of soil and organic matter will be needed. Location is not especially important unless research or experimentation shows they have an unacceptable odor, in which case they should be located near the air purification system and vented into it.
The external structures are those which, while contributing to the overall use of the biosphere, are not directly responsible for its function. They are more for interfacing with the biosphere; entrances, monitoring, temperature control and electrical systems. These are all located outside the biosphere and while several are vital to the operation of the biosphere none of them are considered to be a part of the ecosystem and can excluded from the biosphere proper.
The control building will adjoin the biosphere, and will be connected to the biosphere via a water barrier/airlock. It will serve as a monitoring station, furnace room, changing room for those going into and out of the biosphere, and will provide a work place for anyone monitoring the biosphere.
The foundation for the control building will probably be concrete block laid upon the ground with a minimum of site preparation. The structure may be very small. Construction can be of 2x4 frame with T1-11 on the outside, cheap paneling on the inside, and a metal covered roof.
The control building will provide external monitoring facilities. All data collected inside the biosphere may be electronically transferred (i.e. via computer link) to a computer in the control building to be made available for analysis. An independent system for monitoring critical functions (e.g. oxygen level) should be maintained from the control building. Air pressure differential, power system monitoring and airlock water levels will be monitored directly from the control building. Computer control systems, temperature maintenance and hydroponic solution transfer may be remotely monitored with direct control possible in the event of internal breakdowns. Any discrepancies with the independent system will be noted for immediate repair.
A direct video link will be installed between the control building and the biosphere. This will allow face-to-face conversations, helping to alleviate claustrophobia and cabin fever once the inhabitant is isolated.
An oil-fired hot-water furnace will be located in the control building. Excess heat from the furnace may heat the control building. Circulation pumps will push the water through the biosphere's baseboard plumbing. These pumps will be controlled by thermostats located inside the biosphere. It is estimated that a 80,000 BTU furnace will be needed. [comment added 12-95]
Lockers and/or shelves will be provided for clothes and personal items for people entering the water tunnel to the biosphere.
While facilities may be primitive (e.g. outhouse) a small loft should provide an area for sleeping and a stove, table, chairs and sink will probably be included for those times when the building is manned 24 hours a day.
The airlock will be a double barrier system (see Appendix I). The first barrier from the outside will be water, so anyone entering or leaving the biosphere after it is sealed up will have to dive through the water. Not only will this provide a means to prevent free air movement but will reduce the number of insects and microbes gaining entrance to the biosphere.
A strong disinfectant will be added to the water to kill unwanted microbes. Should deleterious microbe populations that are resistant to the disinfectant build up in the water regular flushing may be necessary.
The water will vary in depth on the outside, depending upon the pressure on the inside. The inside depth will probably be about 1 m to allow for easy access under the retaining wall. The water will be heated to a comfortable temperature (probably 25 degrees C.) when traffic between inside and outside is regular. In order to minimize the heating bill, the water tunnel will be heavily insulated.
The airlock proper will consist of a small room which will serve as a changing chamber. It will be completely airtight and will form an airtight junction with the biosphere. The airlock will have 8" of insulation. The warm water in the water tunnel is expected to heat it; if it does not a circuit can be run from the heating pipes going into the biosphere.
Shower facilities may be built into the airlock so that the chemicals picked up during the water passage can be rinsed off. Since the shower is not a part of the biosphere it must not drain into the biosphere. There will be a certain amount of water vapor released into the biosphere but since the airlock will not be used during closed system operation this is not a vital factor. If it should pose a problem a dehumidifier can be used to maintain the humidity at the same level as the rest of the biosphere.
Although the air in the airlock is isolated from the biosphere it will have the same pressure and roughly the same components. Some exchange is expected to occur through the water which may modify the air in the airlock. To minimize the loss of gasses from the biosphere the airlock proper will be sealed off from the biosphere by a small, airtight door (a refrigerator door would be ideal).
Internal structures are those inside the biosphere that relate directly to its function.
The water systems will be quite complex. Domestic fresh water (both hot and cold) and waste water, and water for the animals (both fresh and waste) and plants (nutrient solutions, primarily) must be managed. Each of these systems is integrated with the other and the overall cycle will be from the dehumidifier, through the human and animal systems, through the nutrient extraction systems, through the plants and back into the atmosphere from which it can be extracted again by the dehumidifier. Since these systems are located throughout the biosphere a fair amount of plumbing will be needed to tie them all together.
As stated previously hot water baseboard heat will be used. The furnace will be located in the control building and the heated water will be piped into the biosphere. The furnace is located outside the biosphere primarily because of its requirement for air. It would be possible to use electric heat but electricity costs are currently very high in the Fairbanks area, justifying the added problems and expense of putting in an oil-fired furnace.
Plumbing penetrating the biosphere wall will have to be carefully sealed and then anchored to prevent the seal from working loose and leaking. A more efficient method may be to run the pipes through the water barrier/airlock.
It is hoped that cooling systems will not be needed. Unfortunately the number of lights which will be constantly burning, together with the dehumidifier and any other electrical appliances, may add up to a greater heat load than the biosphere can shed during summer months. If this should be the case the first step toward cooling the biosphere could be to circulate cold water through the baseboards. It may be possible to simply pump up ground water (typically 2-6 degrees C.) and circulate it. Should the baseboards fail to provide sufficient cooling other systems will have to be tried.
The air balance system will be composed of two parts; one for active air cycling via plant respiration, consumption and biodegradation, and the other a static system for use if the concentrations of various gasses begins to get out of balance.
Pressure control will be needed, and a method of balancing the internal and external pressures.
Carbon dioxide will be "passively" released by animal and, to a certain extent, plant respiration. The active carbon dioxide restoration system will be a vat filled with plant and animal wastes. Air will be forced through this vat providing an aerobic environment for microbes. This system should remove most of the noxious gasses and releases nothing but carbon dioxide. Oxygen will be restored by photosynthesis. One gas these systems may not remove is methane, which will probably be produced in small amounts by isolated pockets of anaerobic microbe activity. Methane build-up could pose a problem in the biosphere and it may be necessary to force the air through an electric heater powerful enough to oxidize the traces of methane in the air. Whether this is a valid concern remains to be seen.
Nitrogen fixation may be accomplished by legumes, which utilize microbial fixation. Should nitrogen build up in the atmosphere (from soil depletion) it may be necessary to install apparatus to convert it from nitrogen to a form the plants can use. In the unlikely event the atmospheric nitrogen becomes too low vats to culture denitrifying microbes may have to be provided.
The static gas system will be composed of gasses that are either pressurized or stored chemically. Oxygen can be stored as water and released by electrolysis (the hydrogen thus released can be stored to burn in times of oxygen surpluses). carbon dioxide can be stored in a silica jell, as simple carbon or even dried plant wastes which could then be burned to restore the proper balance. Since the gasses in the atmosphere will be greatly outweighed by the gaseous elements (especially carbon dioxide) locked up in the ecosystem it will take careful attention to keep them balanced. While the overall balance of the atmosphere is expected to be fairly simple the day to day operation may prove very tricky as one factor temporarily outstrips another. A device that automatically releases one component or another may be needed to keep a proper balance.
Due to the fact the biosphere will be pressurized some method of equalizing the internal pressure with the external atmosphere may be needed. An air pump which would store air in cylinders until the biosphere was to be re-pressurized would work. This won't be used during biosphere operation unless an emergency (e.g. fire) arises.
However should some equipment malfunction occur or if the biosphere were ever to be restructured it may be desirable to remove the water from the airlock for easy transfer of materials. For emergency evacuation a simple pipe with a valve may be installed, or a method of reducing the water level in the airlock below the retaining wall.
Changes in external atmospheric pressure will create problems with the water based airlock unless there is some means of keeping the pressure differential the same. Atmospheric pressure can vary by more than 5% and, with a structure the size of the biosphere, that results in a change in volume of more than 15 cubic meters. An air pump pressurizing air into cylinders as the external pressure drops would suffice. This air could then be released as the external pressure rises. A more elegant solution would be to extend the capacity of the water-based airlock so that internal pressure changes would merely change the level of the water. Both these solutions need to be evaluated to determine the best one.
The various ecosystems in the biosphere (especially the plants) will produce considerable quantities of water vapor, probably on the order of 200 to 400 liters per day[A5]. The humidity needs to be held down not only for human comfort but for proper plant growth. To do this dehumidifiers will be used. A 48-pint (22-liter) dehumidifier (about 35x50x55 cm[A6]) would remove approximately 1 liter of water per hour (based on 25 degrees C and 60% relative humidity), and 8 or more would be needed just to keep up with plant respiration.
Dehumidifiers are not designed to provide a pure water source and may have metallic surfaces which could contaminate the water, so it may be necessary to paint the dehumidifier fins to prevent this; many metallic substances are toxic to plants and animals even in trace amounts.
Most of the crops grown in the biosphere will be grown hydroponically. Several large vats for biological breakdown of plant wastes, with smaller vats for soaking nutrients from animal wastes, will be needed as well as tanks for storage of the resultant mixes. Plumbing will be extensive, with aquariums, "gray water", urinals and dehumidifiers as water sources and plumbing to each plant tray for output. Since the plant trays will be flushed (and not flooded) they will need drains back to the holding tanks. Many pumps will be required to move the various solutions. Plant trays will need to be waterproof and filled with sand or gravel to provide a medium for the plants to grow in. While not required, monitors and a remote control system would greatly ease the chore of caring for the garden.
Several fish tanks will be used to insure against loss in the event of fatal contamination or breakage, to provide a more secure environment for breeding fish and to keep fish of different sizes in different tanks to minimize destructive competition.
Due to the density of the fish population a method of supplying oxygen to them may be needed. This will probably be done with a standard aerator.
While the size of the fish farm has yet to be calculated, five 80-liter aquariums will probably be needed. Tilapia are capable of very dense packing and each aquarium is expected to be able to support an average of 60 adult fish[A7].
The breeding aquarium will be a cone shaped tank, pointed on the bottom. Research has indicated that this is the most effective method of breeding Tilapia since it limits consumption of the Tilapia fry by larger Tilapia by providing the fry with a place to escape[A7].
It may prove necessary to raise special food for the Tilapia fry. If so a special tank will have to be built to raise phytoplankton for them. Experiments need to be done to determine if an acceptable survival rate can be obtained with the food that will be available in the biosphere.
Poultry will be kept in cages on the first floor near the airlock. The cages will be ventilated directly into the air purification system to help remove odors. At least two cages should be built to allow for separating the birds into different groups. Incubators to hatch eggs may be necessary, especially if the initial brood is introduced to the biosphere as eggs.
Cages will probably be of plywood. An observation window looking into the cages could be of use. Wire screening will be avoided because of the problems with corrosion and contamination.
The primary lighting system in the biosphere will be extensive because of plant requirements. Lights will also be required for personal use.
A number of crops will need cyclical lighting to complete certain cycles (e.g. the C4 pathway utilized by corn and sugar cane[A8]). Lights will either have to be controlled with a timer or manually to give the plants the right duration of light.
It may prove desirable to suspend the lights over certain crops (e.g. wheat) so that they can be raised and lowered, maintaining the desired intensity of light as the crop grows.
Many crops will not require light cycling; these crops can have their lights wired to a single switch as they will never be turned off during biosphere operation.
The value of "grow lights" may not justify their cost; light of the correct balance can be obtained by using a combination of fluorescent and incandescent lights[A9]. Chlorophyll, most plants' primary light trapping-pigment, absorbs light from 400 to 450 nanometers (blue) and from 600 to 700 nanometers (red)[A8]. Fluorescent light is primarily in the lower, or blue, range of the visible spectrum while light from incandescent lights is primarily in the higher, or red, range. By using both types of lights an adequate balance that meets the plants' requirements will be obtained.
There will be nothing unusual about the domestic lighting, although special care should be taken to assure that the living quarters are well lit with no dark corners to help alleviate cabin fever. Good reading lights, desk lights and lights for the cooking area are needed. Care in placement and using appropriate bulbs will satisfy the needs of the inhabitant.
The monitoring systems will be responsible for watching over many of the functions of the biosphere as well as for detecting hazardous conditions such as declining oxygen levels or fire. Most of the monitoring could be controlled by computer and would not require any human input. Such a system will be used if financing permits. Back-up monitors for critical conditions will also be used (e.g. fire alarms).
Many of the monitoring systems mentioned below are optional. They would provide interesting data and could show where problems are occurring but are not actually necessary for the operation of the biosphere. Financial or time constraints may require that some of them be left out, or installed at a later date.
The crop lighting level can be monitored in each discrete crop area using photoelectric cells tied into the computer. This would automatically monitor light level and duration, providing data on conversion efficiencies. It could also detect lights that have burnt out or are not functioning properly.
Several different water systems need monitoring; fresh and waste water levels, hydroponic water levels, aquarium water levels and the levels in any nutrient soaking solutions. This would show the water flow through the system and whether there was an excess building up in any part of it.
Rates of water transfer from one system to another would provide useful data to help pinpoint and reduce excesses and shortages, though this may not be practical in the working biosphere.
Close monitoring of the oxygen level will be needed during the initial startup of the biosphere to make sure that the oxygen is not depleted. Shortage of oxygen not only results in faulty judgment but can lead to hypoxia and even death. Therefore alarms will be set to go off in if the percentage of oxygen in the atmosphere falls below a predetermined value. Should this occur a source of pure oxygen and/or compressed air should be available to the occupant to use while correcting the problem.
Carbon dioxide is not as vital as oxygen as the lack of it is not immediately fatal to plants. However an adequate supply must be available for all but the shortest periods or plant productivity will be seriously impacted. Excess carbon dioxide needs to be monitored a little more closely, however. Too much will cause increased respiration, heart rate and, more seriously, the will affect animals (including human) acid/base balance.
Nitrogen is critical to plant growth, but is restricted to microbial fixation to replace the nitrogen compound lost from the ecosystem into the atmosphere. If an adequate supply is not available the nitrogen fixers will perform poorly, if at all. This is not expected to be a problem since the major component of the atmosphere is nitrogen. However an increasing level in the atmosphere may indicate that the level is decreasing elsewhere and the niche where it is being lost needs to be found and compensated for or eliminated. Thus nitrogen monitoring equipment must be installed.
Maintaining the proper temperature is important to insure proper crop growth, so there will be thermostats at strategic points. The fish tank may be on a separate circuit to maintain a different temperature from the rest of the biosphere. In addition to the thermostats a computer monitoring system may be employed to collect data on plant growth rates at different temperatures.
The biosphere environment is expected to be fairly high in humidity, which should retard the fire hazard to a certain extent. In the event of a fire all the oxygen would be quickly consumed. A supply of oxygen or compressed air should therefore be readily available to the occupant at all times and an escape hatch needs to be rigged for easy escape from the bedroom. With these precautions, and a good fire alarm system, the biosphere will be safer than a conventional house.
Most of the monitoring systems can be tied into a central computer. This computer could keep track of the data and make it available to the control building whenever requested. Data could be collected via links with sensors designed for computer interface. While not critical to biosphere operation it could track variables affecting biosphere operation and might identify potential problems before they get serious.
Data on power usage will be useful to future applications of a biosphere so it will be desirable to keep track not only of the total electrical consumption but where each fraction was used. Fuel oil used in heating and the power used for cooling are of less concern since future applications of the biosphere will have substantially different heating and cooling parameters. This data would be of interest, though, since it could be used to determine the overall heat output by the biosphere.
While it is hoped that the biosphere will not be affected by the external air pressure, variations should be monitored in case there is a period of pressure which exceeds the design limits of the biosphere. Should that occur the air pressure in the biosphere may have to be modified.
The water level in the airlock must be maintained above the level of the retaining wall (see diagram) or the biosphere could implode from sudden depressurization. Should it be in danger of doing so either more water would have to be added or the pressure inside the biosphere reduced.
While computer controlled systems are not entirely necessary and may not be included in the initial biosphere configuration they would improve control and relieve the burden of manually operating many of the biosphere systems. It would be practical and efficient to use computer control for plant lighting, hydroponic fluid flow, aquaculture water level maintenance, temperature control, airlock water level control, air pressure regulation and possibly atmospheric maintenance (releasing oxygen or carbon dioxide).
All these systems would need considerable wiring, and some would have to be done during biosphere construction. Remotely controlled pumps, switches and valves would have to be installed in the appropriate places for the computer to operate them, and as walls and ceilings are built any wiring to go inside them must be installed.
The electrical system in the biosphere will be significantly more complicated than that of a house. It will not only have to provide for domestic cooking and lighting but also the energy to drive all the functions of the biosphere.
The hydroponics will need indicators on the tanks showing when they are empty or full (these could be connected to the computer), and pumps will have to be wired to either a remote control (e.g. computer) or manual switch.
Lighting for the plants is expected to be very complex. No exterior source of light is to be used so all the biological energy of the biosphere will be from plant lights. Different plants have different lighting requirements, in terms of both duration and wavelength. Fluorescent and incandescent bulbs will be used in combination to provide the needed spectra, which will increase the wiring. Most of the lights will be suspended from the ceiling and the wires will run through a switch, to the wall and thence to the distribution box.
Standard wiring practices will be used in the domestic wiring. To decrease heat impact a microwave oven will be used in combination with an electric cooktop. Outlets should be numerous enough to provide for a large combination of devices (particularly computers and related devices).
Aquaculture systems need pumps, lights and heaters, all of which will need to be wired. Lighting systems for the poultry, fish, various hallways and the airlock will also be needed. The air purification system will need to have pumps to draw the air through it, and it may prove desirable to have fans to prevent stratification of the air in the biosphere. The dehumidifiers will need power outlets, as well as the air pumps and the waste management systems.
Electrical outlets need to be placed at strategic points throughout the biosphere to allow for modification or addition of various systems. These details need to be incorporated into the final blueprints.
A continuous power supply is crucial to the successful operation of the biosphere. The oxygen supply is dependent on plant photosynthesis and without lights to drive the photosynthesis, oxygen would rapidly become depleted. While most of the power is expected to be derived from GVEA (the local power company), a good backup system is needed. A dual reserve is planned, one based on batteries and a second based on a standby generator. Both these standby systems will be located outside the biosphere, possibly even in a shed of their own. Should the system be designed to withstand a nuclear war the power system should be buried in its own room near the biosphere with easy access from the biosphere.
A TV and a video system capable of visual phone conversations to the control building is desirable to help alleviate claustrophobia and to provide entertainment.
How to deal with waste has not been decided. Both microbial breakdown or forced via burning will need space set aside for that purpose. If microbial breakdown is used a number of large containers need to be equipped with fans to force air circulation through the decaying biomass. If the wastes are burned then an autoclave (kiln) will need to be installed.
Furnishings are going to be fairly Spartan and simple. This is not an area of importance to the operation of the biosphere so unless considerable funding is obtained the cheapest serviceable items available will be used.
If no walls are put between the bedroom and the crops it may prove desirable to build a light barrier immediately surrounding the bed. If the fans, pumps and other gadgets prove to be noisy a sound barrier may also be added.
When construction is complete the biosphere will be essentially lifeless. To introduce life to it will require careful planning and a gradual build-up of the needed cycles and support systems. All materials imported into the biosphere, both living and non-living, need to be logged so that the exact content of the biosphere can be determined at any time. Almost all life will be introduced as seeds (in the case of plants) or young (in the case of animals).
Every effort will be made to maintain an environment free of harmful microbial life, while useful microbial life will be imported, possibly via soil samples, for such things as decaying waste products and fixing nitrogen. Contaminating microbes will be dealt with as they appear, hopefully with non-toxic methods like humidity changes, strict weeding and possibly elimination of susceptible crops. It would be preferable to get the biosphere started and sealed during the winter when there are few, if any, micro-organisms floating in the outside air. The cold would also help slow, if not prevent, bringing in pests on boots, clothing and anything transported into the biosphere.
Initially biosphere operation will be completely open; any material needed will be imported. Ventilation will be via forced movement of air through the biosphere; any nutrients the plants need will be imported and most of the foods needed by animals (including human) will be imported. As the ecology is built up and the elements begin to cycle, outside input can be gradually phased out.
The initiation process will change the biosphere from a lifeless, artificial structure into a living biome. Introducing life to the biosphere should not be much more difficult than planting a garden. A little more attention to detail will be paid to things like quantities used, but this is more for experimental data than for operational purposes.
The plants in the biosphere will have to provide a continuous flow of food, rather than the more common seasonal crop harvesting seen in most of the world. Basically this means that any given crop has to be planted in small patches on a regular basis. This will allow gradual harvest and prevent an overabundance at any given time. Given this criterion it means that the crops of the biosphere will not be fully productive until the slowest growing ones are about to be harvested, probably 5 months or more after the first were planted.
Since the biomass is to originate from imported fertilizer it can not be restricted until sufficient biomass has been accumulated. Therefore the plants are expected to need synthetic hydroponic solutions, at least in part, well into the first year of operation. As the nutrient cycling builds up the artificial fertilizers can be gradually phased out until the hydroponics are based on internally generated nutrients, thus closing the cycle.
Some crops will probably prove to be unacceptable, either in compatibility with other plants (e.g. temperature), in productivity, or for some other reason. They will have to be eliminated from the biosphere and a substitute provided. Since the substitute would then have to be integrated with the system the initial kinds of plants should be chosen carefully.
Since the biosphere is totally open to the atmosphere at this point no effort will be made to balance carbon dioxide and oxygen absorption/output of the plants. The only goal at this point is to assure an adequate crop production for human and animal inhabitants of the biosphere.
As previously stated the best fish for intensive fish farming is Tilapia. They are omnivorous, highly productive and easy to raise. They have a good tolerance for such things as low oxygen, salt water and poor water quality.
Before the fish can be introduced to the biosphere their habitat must be prepared. The aquariums need to be filled and heaters, filters, monitoring apparatus and any other desired equipment needs to be hooked up and its operation verified. Temperature should be allowed to stabilize and, in the areas where crowding is expected, aerators need to be installed.
The fish will be introduced to the biosphere as fry. These will be fed either an imported fish food or, if the crops have grown enough, will be fed directly from biosphere produce. When the fish are old enough to reproduce they will be divided into two populations. One will be used for breeding purposes and the other for consumption.
After the tanks are filled a continuous flow of water from the dehumidifier will provide fresh water for the fish. Water draining from the tanks will run into the hydroponic system, providing nutrients and replacing the water used by the plants.
Poultry will be introduced as eggs and incubated for the initial brood. It is important to have a number of different genotypes in the first brood since the population will be small and breeding problems could pose difficulties.
Once the first brood of poultry is large enough selective breeding should be started. Eggs will be cared for either naturally or in incubators, and as the surplus poultry matures they will be eaten or devoted to egg production.
The hydroponic system will not only provide a medium for transferring nutrients to the plants but for extracting those nutrients from the various degradation systems. The overall concept is fairly simple; a gravel medium for plants to grow in which is flushed several times daily with a nutrient solution derived primarily from soaking decaying biomass.
The hydroponic solution will be derived from several sources. Water from the aquarium, vats in which chicken wastes and earthworm wastes are soaked to extract their nutrients, and the biodegradation system (which will be a combination of vats for decomposition and soaking). Initially this mixture will be of introduced fertilizers which will be phased out as the biosphere is used and the nutrient extraction vats are filled, increasing the natural nutrients until they balance plant use.
Tanks used to store the nutrient mix may build up sediments and un-utilized waste products after a period of time. Wastes like this may have to be pressure-cooked to release their elements back into the ecosystem. Another option could be to use the sludge to grow crops in, hopefully breaking down the remaining materials. This would require special containers (i.e. non-hydroponic) to hold the soil.
The atmosphere of the biosphere will be the last thing to be cut off from outside supply. As the exterior input of air is reduced any system needed for air purification must be started. If the concentration of any gas declines the cause must be determined and methods of releasing it found while the necessary gas concentration is maintained by releasing stored gas. If the niche into which the gas is lost is a permanent one then extra gas will have to be imported until the niche becomes saturated. Surplus gasses can be chemically stored.
There are numerous cycles in the biosphere. The more important are water, carbon dioxide, oxygen, nitrogen and minerals. The balancing of these cycles is expected to pose the most difficult and perplexing problems, most of which will be discovered only after starting the biosphere. It may prove impossible to overcome them, especially in a system as small as this one. It is, however, possible in theory. Determining if it can be done in fact is the goal of this project.
The water cycle is a simple one. Plants, animals and open water containers will put water vapor in the air which will be condensed by dehumidifiers and returned to the liquid water system. Gages or observation will be used for monitoring. Control is done by turning the dehumidifiers up or down. Since plant respiration will greatly out-weigh other components in the system the other cycles (e.g. animal consumption) will be easily provided for.
The air inside the biosphere is expected to be composed of the same elements as 'normal' air is, mainly nitrogen and oxygen. The carbon dioxide level will be kept at a slightly higher level than normal air to promote plant productivity, but not so high as to cause human problems. Air composition will have to be carefully monitored to assure that the important components remain at the proper concentrations.
In almost all biological activity when oxygen is consumed carbon dioxide is given off. Therefore as long as a balance is maintained between release of oxygen by plant growth and animal and microbe consumption of oxygen the oxygen level should remain constant. It is possible, however, that some oxygen may get trapped in a useless form such as rust. Should the oxygen level begin to decrease, these niches need to be found and either eliminated or saturated so they no longer absorb oxygen.
Forced balancing can be performed by electrolyzing water or burning hydrogen (as discussed under section VI. D. 1. above).
Carbon dioxide balancing may more difficult than the oxygen; the total weight of the atmospheric carbon dioxide is very low when compared to the mass of carbon locked up in plants and that being exchanged on a daily basis. Wild swings in concentration can easily occur so an even balance between photosynthesis and respiration must be maintained. The method for forced balancing is similar to the balancing of oxygen; burning of plant matter, or carbon, to release more carbon dioxide in the event of low concentrations, or chemically locking it up in something like silica jell if there is too much.
Initial carbon dioxide will be obtained from outside air. As the air flow through the biosphere is restricted, more and more of the carbon dioxide will originate from the living organisms inside the biosphere. Once the biosphere is sealed the percentage of carbon dioxide in the air can be raised to the optimum value, limited more by animal tolerance than peak plant productivity.
Plants can not fix nitrogen gas but legumes have evolved a symbiotic relationship with the bacteria of the genus Rhizobium, which grow in special nodules in those plants. The plant provides the bacteria with the nutrients they need for growth and in return obtain nitrogen which the bacteria convert from N2 into NH4+. This seems the best method to obtain nitrogen from the air.
Other bacteria are responsible for denitrification whereby fixed nitrogen is 'burned' and releases nitrogen gas. By careful culturing of either the 'fixing' (via growing legumes) or the 'burning' bacteria it should be possible to maintain a balance between atmospheric and fixed nitrogen.
Methane will always be produced in minute quantities and some sort of artificial burner may have to be built to prevent it from building up in the atmosphere if microbes fail to remove it.
Argon, being an inert gas, is not expected to have any relevance to the biosphere. It will no doubt be present but only as a static element in the atmosphere.
Carbon monoxide is deadly to any animal utilizing hemoglobin for oxygen transport. No known source for carbon monoxide exists but if a source does develop the biomass filter may remove it or it can be burned in a method similar to methane.
Ozone is a very corrosive gas. It is, however, an unstable molecule so the chances of any problems with it are very low.
Hydrogen sulfide and ammonia (and other nitrogenous gases) may be produced in minute quantities but are expected to absorbed easily by the biomass air filters.
Other trace gasses (neon, helium, krypton, hydrogen, xenon, and radon) are present in such minute quantities as to be nonexistent for practical purposes. There is a possibility hydrogen may be released by some biological or human function; if so it would be handled in the same manner as methane. Indeed if a methane 'burner' is installed it will be burned along with the methane.
There are several macro- and many micro-nutrients which must be accounted for. The more important macro nutrients are nitrogen, sulfur, phosphorus, potassium, calcium and magnesium. These elements are vital for plant growth. Any point in the cycle where these nutrients are liable to concentrate needs to be identified and either eliminated or saturated. These nutrients must pass from the plants through the various animal, earthworm or microbe systems, and end up in a form which is--or can be--dissolved in water to be returned to the plants.
The micronutrients are less well defined and following their cycles may prove difficult due to the very small amounts that are present. Iron, boron, zinc, manganese, copper, molybdenum and chlorine have all been identified as necessary for healthy plant growth. While lack of these nutrients can be identified in most cases from plant morphology, tracing and replacing the missing mineral could be difficult. System saturation may prove the only practical method though great care will have to be exercised to prevent toxicity.
Plants are the most abundant part of the ecological system and will produce all the biological energy utilized by the biosphere. To maintain a continuous population is the goal of crop cycling. A spectrum from seeds to mature plants is desirable at all times. This requires a weekly, if not a daily, planting schedule. Ideally for every plant that is harvested a new one is planted. This could prove too tedious and it may be possible to plant on a weekly schedule; most plants will remain 'ripe' for a period of time, and not all plants will grow at quite the same rate.
Many plants will produce seeds in the course of producing human food. Plants which do not will be a problem. Many plants (e.g. carrots) are on a 2 year cycle which makes growing seeds a slow process. Ideally artificially cloned seedlings would be usedA4. This technology has not been perfected yet so it may not be possible to use it in the biosphere. Thus an area for seed production will have to be set aside and seed plants grown from the very first day. A large enough genetic base, in the form of stored seeds, needs to be maintained to prevent deleterious mutations due to inbreeding.
Tilapia are naturally very prolific. The rate at which they breed may even be a problem; the population tends to explode yielding high concentrations of small fish with few bigger (and more eatable) fish. At the University of Arizona Environmental Research Lab some success has been had preventing breeding by raising the Tilapia in salt water[A2]. This is not feasible here because of the problems of extracting wastes from the salt water. Should it prove desirable a salt water ecosystem would have to be devised to utilize the fishes' wastes. The problem will more likely be solved by selectively removing the smaller fish at given intervals to keep a sufficiently low density of fish for maximum growth.
Poultry propagation may have problems from inbreeding, especially if the biosphere is operated over a long period of time without any new genes being introduced into the population. Inferior birds will have to be vigorously weeded out and only the healthiest birds used for breeding.
Human cycling will be impossible unless the biosphere proves capable of supporting more than two people. Over the duration of the initial experiments only a single inhabitant is expected to occupy the biosphere negating any possibility of overpopulation. Future experiments may include deliberate overpopulation to identify areas susceptible to stress. Future biospheres designed for large populations will have to exercise some type of population control.
Energy will flow through the biosphere. All biological energy will originate with the electrical current flowing into the biosphere. This will be converted into light, which will transfer the energy to the plants. The plants will use it to convert carbon dioxide into an energy source humans can use--grains, vegetables and other plant foods, as well as roots, chaff and stalks which can be eaten by fish, poultry and earthworms. The energy thus transformed into foodstuffs is utilized by the inhabitants of the biosphere to grow and reproduce. In doing so they give off energy in the form of heat, which the biosphere will shed into the surrounding environment.
The primary concern with energy flow is to make sure the biosphere does not overheat. This may mean some sort of cooling system, or a reduction in insulation. Since it will not be known until the biosphere is working just how much energy it will radiate no calculations can be done; the biosphere itself will have to demonstrate heat loss or gain.
Sealing refers not only to the elimination of external air circulation through the biosphere but also terminating the import of supplies. It will be a gradual process as the biosphere comes to life and begins producing its own materials.
The first import to be eliminated will be animal food. As plant production increases to its maximum level harvests will gradually increase and there will be a corresponding decrease in the need to bring in outside foods for fish, fowl and man. When the system reaches a balance between production and consumption the cycle can be considered closed.
As waste products build up the nutrient production from those wastes will grow. When this nutrient production matches the nutrients consumed by the plants fertilizers will no longer be needed. Analysis of the hydroponic solution produced from the waste products will tell us when fertilizer is no longer needed.
Ventilation fans can be turned off and the biosphere isolated only after everything else is cycling properly. This will provide a stable system to start the final experiments--trying to maintain good air quality.
Once the biosphere is completely isolated from the outside world the real experiment begins: can the system be maintained in equilibrium for long periods of time? It is likely not to work on the first try. But as the biospherian gains experience in operating the system a balance should be achievable.
Day to day routine will, no doubt, become monotonous. There should be plenty of work to keep one busy but the work will be more repetitive (e.g. analyzing the hydroponic solution each day) than creative. This could lead to boredom so games, phone conversations, reading and TV are all expected to play a large part in the daily routine.
When the biosphere is initially sealed hourly readings of air content should be taken to identify trends before they become serious. As experience is gained and the air proves stable for longer periods, a daily check will suffice. Other things are not quite as critical, though hydroponic solutions, humidity, temperature and water levels all need to be monitored on a regular basis. The fish and poultry will need to be fed and watered, the garden will need to be inspected for infection, proper watering, and some plants will have to pollinated.
Systems that are not automated must be managed manually (e.g. the hydroponic watering system). To add to these chores preventive and repair maintenance on machinery will have to be done. Broken machinery which is not repairable will have to be replaced unless a spare is available.
If the biosphere can stay stable for as long as a year it will be considered a success. Longer periods may be desirable but at that point it is expected the biospherian will wish to leave, though another person could probably move in without too much disruption. If the biosphere won't stabilize for long periods of time it will show what the constraints are and, once these are known, it may be possible to compensate for them in future systems.
The prefix "bio" refers to biology and "sphere" is sometimes used to denote a closed system. Thus the word biosphere refers to a biologically closed system. Such a system is not really totally closed; energy almost always permeates the barrier isolating the biosphere, be it an impenetrable wall or the vacuum of space. In the case of the biosphere of our home planet this energy is in the form of solar radiation. Not all organisms utilize solar energy but it is the driving force behind earth's ecology. In artificial biospheres the driving energy does not have to be solar radiation; any form of energy which can be converted to light is acceptable.
Energy flows through a biosystem, driving its life forces. Energy usually enters as light and escapes as thermal radiation. Other components however, are constant with no significant exchange with the outside. An artificial biosystem [comment]has yet to be devised in which man can live for prolonged periods.
The biosphere this paper proposes should be able to support one person easily. There is the possibility that two or three could be supported; this will have to be determined from actual biosphere operation. The goal of this project is not to provide a place for a person or persons to live, but to determine the limits of a biologically closed environment, and to overcome any problems that would prevent the biosphere from functioning. The ultimate application would be colonies in space and inhospitable portions of our own planet. It would also demonstrate a viable method of surviving nuclear war.
It is not possible to truly isolate a small, artificially constructed and supported biosphere from the outside world. Machines, plumbing, interiors and exteriors are all subject to wear and would eventually need replacing. Larger systems with more resources could conceivably be made self-sufficient by recovering used systems. More likely it will always prove easier to import certain kinds of equipment. While breakdown is always possible, equipment used for the duration of this experiment should not wear out. Should a breakdown occur the needed parts will have to be imported. This is not considered an important factor since only biological systems are being evaluated.
There are a number of groups working toward a stable biosphere, both American and Russian. Their methods are the reverse of my technique for they seem to be investing large amounts of manpower in determining the constraints before the biosphere is built; I will build the biosphere and then invest the time and money in making it work. While this runs the risk of constructing a system that inherently unstable, it will be a great deal cheaper to build. Unless funding is obtained this is of prime importance. Exact data is not needed to build and run the biosphere; it may help but the biosphere should work without calculating everything down to the last detail.
Biospheres are possible. We have the evidence all around us. Whether man can duplicate nature remains to be seen.
Note: Letter of reference refers to the paper number. Numbers refer to the reference within that paper. (There will be future papers which will use these same references.)
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