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Mars Base 0: An Alaskan Platform for a Martian CELSS
Note: this paper was written and presented for a conference in London in April, 1996. However it is such a good definition of what we are working to accomplish that we present it here as our page on Mars Base 0.
In many ways the Martian climate is similar to the Interior Alaskan winter climate. Cold, limited sun light and low humilities predominate both locations. Mars Base 0, a semi-closed ecological life support system (CELSS), is being built in Fairbanks to facilitate the development of a fully closed system. With the climatic similarities this will make an excellent facility to investigate many aspects of operating on Mars.
Any base operating for any length of time on the surface of Mars will require CELSS technology. Many of the raw materials require for crop production are available on the surface of Mars so true closure will not be required. As a part of the Nauvik Project, which will be a fully closed ecosystem, the International Space Exploration and Colonization Company (ISECCo) is building Mars Base 0. Designed as a semi-closed greenhouse Mars Base 0 will be used to develop ecosystem technologies. The limited sunlight and temperatures ranging down as low as -60 C during the Fairbanks winter will allow us to investigate many of the problems associated with operating a CELSS on Mars. While heating on Mars will not use the same methods as we shall use, some idea of the difficulty in keeping a greenhouse warm will be gained. During the Martian summer cooling may be required - and in our mild (20's C) Alaskan summer it definitely will be - so cooling options will be explored. Overall design of Mars Base 0 will be applicable to a Martian base; our semi-cylinder, 7.5m wide by 13.5m long would be equally useful on Mars. Although construction techniques would be significantly different we shall establish a semi-sealed environment similar to that required for a Martian base.
Although interior Alaska no longer experiences dust storms, ice for will effectively simulate the Martian dust storms. We shall rely on artificial lighting at any time natural light proves insufficient. There are a few significant areas we will not be able to address. Gravity, atmospheric pressure, power production and Martian construction techniques are all outside the realm of this project.
Our primary goal is to produce most of the food needed to support a person (60-80%). Along the way we shall learn how to deal with areas as diverse as toxic gases, biodegradation, pest infestations and survival during crop failures.
Any base operating for prolonged periods on the surface of Mars will require closed ecological life support technology. This technology, called CELSS, is vital for bases in space due to the high cost of transporting food, air and water.
Many of the raw materials required for crop production are available on the surface of Mars so a completely closed ecosystem is not be required. In the fall of 1995, the International Space Exploration and Colonization Company broke ground on a greenhouse that will mimic many of the factors that would go into designing such a facility on Mars.
We have decided to name our greenhouse Mars Base 0. Mars Base because it will be an ecology that would survive on Mars with little change; 0 because it is not on Mars! It will have similarities to a small base on Mars, though there will be some significant differences too. But with a little imagination one could picture oneself on Mars while living in Mars Base 0.
Mars Base 0 will be a semi-closed ecology that will support one or two people in an environment that has striking similarities to the Martian environment--at least during the winter time. During the winter Fairbanks' limited sunlight and temperatures ranging down to -55 C (-70 F) will allow us to investigate many of the problems associated with operating a CELSS on Mars.
We expect to import air, water, and some nutrients. How far we can carry closure depends in part on how well we manage to seal our structure. During the summer we will not attempt closure of air or water because of overheating. In the winter, however, we will be able to shed excess heat and keep the structure partially sealed.
Overall design of Mars Base 0 will be applicable to a very small Martian base; our building layout, 7.5 m wide by 13.5 m long (24'x44'), is similar to that expected to be needed on Mars. Although construction techniques will be significantly different we shall establish a semi-sealed environment similar to that required for a Martian base. The portions of our structure which are not glass will be super-insulated, for we intend to operate it all year. It will be a complete ecology, capable of supporting one or two people on a semi-vegetarian diet. In one end of the building we will have an efficiency apartment.
The structure will be shaped like a Quonset hut (half cylinder). The south wall, to the peak of the roof, will be glass (or some other clear material, like lexan). The north side of the cylinder's walls will be made of plywood coated with fiberglass and resin to seal it.
The axis of the structure will be oriented E/W, with the N half super-insulated. We'll have a concrete floor, 0.5 m (1.5') high concrete walls that will contain the soil for our crops.
While heating on Mars will not use the same methods as we shall use, some idea of the difficulty in keeping a mostly-glass structure warm will be gained. During the Martian summer cooling may be required - and in our warm Alaska summer it will definitely be -- so cooling options can be explored.
Our power source will be electricity. Since our focus is on ecology, we shall be buying all needed power from the local power company. A CELSS on Mars will probably use either solar or nuclear power.
We do not expect to achieve a good seal, though the structure will be partially sealed. If we can reduce the air exchange down to 10% daily we'll be ecstatic. This will allow us to track atmospheric gasses, (if not deal with them). In a fully closed ecosystem any kind of gas such as methane that builds up in the atmosphere is a potential problem. Mars Base 0 will exchange enough air so we will not have to do more than observe problem gasses. In a Martian CELSS air may also be exchanged with the outside environment to flush deleterious gases.
We will partially seal Mars Base 0. The concrete, plywood and all glass junctions will have an airtight coat of fiberglass cloth saturated with epoxy resin. Cooling is going to be very expensive, so until we can afford to operate some kind of air conditioner we will just blow air through Mars Base 0 when it overheats. Vents will be cut in both ends and when we want air closure we'll seal them. The door will be an old freezer door. An emergency exit will be a 3' diameter ring sealed with mylar, with a knife handy to hack your way out.
Mars vs Alaska: An Environmental Comparison
Perceptions of your environment depend entirely on what you are used to. Most people would consider an Alaskan winter to be pretty extreme example of earth's environment. It doesn't bother many of us who grew up there; we are used to the -40 temperatures. For example, I don't consider -30C (-20F) very cold. Dog teams prefer -25C(-10F)-they overheat when it is warmer. People living in space will no doubt have the same attitude toward their environment. They will be used to the extreme temperatures and vacuum and consider the difficulties they entail normal.
In many ways the Martian climate is similar to the Interior Alaskan winter climate. Cold, limited lighting and low humidity predominate both locations. With the climactic similarities Mars Base 0 will make an excellent facility to investigate some aspects of operating a base on Mars.
Although interior Alaska no longer experiences dust storms, ice fog will effectively simulate the Martian dust storms. We shall rely on artificial lighting any time natural light proves insufficient for our crops.
Living in Mars Base 0 during the winter will be similar to living on Mars. You will grow your own food. Most of your time you will be inside. Whenever you go outside you will dress in heavy cloths that in many ways are just as cumbersome as a space suit. Probably the major difference between Mars Base 0 and a base on Mars is that we expect to heat with wood (costing us labor, rather than money) and, of course, there will be a difference in gravity!
Between December 1st and March 1st the minimum temperatures in Fairbanks go as low as -56C (-70F). This corresponds with the Martian equatorial regions, where the average temperature is -63C (-80F) (Hamilton). Incident solar radiation during the same time is also similar.
Another striking similarity is the partial pressure of CO2. While the Martian atmosphere is very thin, it is almost entirely CO2. This gives a partial pressure for CO2 on Mars of 0.06 psi. This corresponds well with the partial pressure of CO2 on earth; while our total pressure is much greater, CO2 is such a small percentage of our atmosphere its partial pressure is only 0.04 psi.
There are global dust storms on Mars that can obscure the surface of the planet for prolonged periods (Kaufmann). This will pose serious problems to any Martian CELSS. It results in a more extensive power and lighting system than would otherwise be necessary. While Fairbanks does not currently suffer from dust storms (although during the ice age there were serious dust storms in interior Alaska (Weber)), our sunlight can be restricted due to winter fog, clouds, or the fact that we're only about 100 miles from the arctic circle. On the shortest day of the year we have around 3.5 hours of sunlight-and that is at such a low angle that the incident radiation is very low. Thus even on a sunny winter day we get less light than is available on Mars. Therefore our artificial lighting system will be very similar to that needed for a Martian CELSS.
The humidity during the Fairbanks winter is low, averaging less than 20% (personal observation). The Martian humidity is significantly lower at 0.03% (Hamilton). This will not have much impact on operating a closed ecosystem.
There are a number of dramatic differences between Mars and Fairbanks, atmospheric pressure the most serious. On Mars the average pressure is (0.07-0.12) psi. On earth it is 14.5 psi. While it is beyond the scope of our project (our structure would not withstand the strain), investigation of a CELLS plant module using a simulated Martian atmosphere (composition & pressure) would be a logical extension to our project.
Possibly of even greater significance to operating a CELSS on Mars is the lack of nitrogen in its atmosphere: it contains only 3% (Lide). This has serious ramifications for a Martian CELSS, for earth organisms that fix nitrogen are adapted to a nitrogen-rich environment. Replacing lost nitrogen could be the greatest difficulty in operating a Martian CELSS. If the opportunity arises we shall experiment with a nitrogen-deprived atmosphere in Mars Base 0 by replacing nitrogen with another inert gas.
The Martian atmosphere has very little free oxygen. This is quite different from earth's atmosphere, but is not seen as a significant problem. There is plenty of oxygen available on Mars as the soil has plenty (Chandler), and the atmosphere has oxygen "available" from CO2. In Mars Base 0 we will not be able to balance oxygen, nitrogen, or carbon dioxide due to our imperfect seal.
There is no way of addressing another big issue: gravity. The Martian gravity is 38% of earth's (Abell). Other major issues our CELSS will not address are soil differences, year length and the spectral qualities of the Martian sunlight (Martian sky is pink, opposed to Earth's blue color).
We do not plan to use unusual gardening techniques. Though our crops will be a little exotic for Alaska, for we will grow such things as rice, soybeans and sorghum. We will also try aquaculture and perhaps livestock such as chickens or rabbits. Thus our initial ecology will be as simple as possible.
The ecology will maximize human food production. To assure a constant flow of food from the ecosystem to the human, we are aiming at a capacity somewhat higher than needed. Surplus production will not be wasted. It will be used to produce 'luxuries' such as eggs, which require greater primary production capacity. If the human food supply is stressed we can forgo these extras, and eat the grain otherwise intended for livestock.
A significant percentage of the primary production is not eatable. In agricultural ecosystems this production is consumed primarily by soil microbes, and is never utilized by humans. In natural systems this energy cascade is intercepted in several ways. By incorporating these 'interceptors' we can reduce the total crop area needed to support our human. We shall experiment with several species that make use of the dregs of the ecosystem; earthworms to consume human and animal waste, ants and termites to consume woody materials. These can then be used to feed higher species like chickens or fish.
Commercial agriculture is done in two dimensions (area), with special attention paid to a third dimension: time. Yield is maximized per area per time, with little (if any) attention paid to crop height. For CELSS applications a fourth dimension becomes critical, for reducing the total volume enclosed will reduce costs. Thus design must maximize yield per volume per time. This means incorporating highly efficient plants of short stature.
We have used conservative estimates for sizing our crop area. The smallest theoretical area needed to produce 3,000 kcal/day is 4 m2 (40 square feet)(McCree)! More realistic figures are obtained from good field production where 100 m2 (1,000 square feet) is needed to produce 3,000 kcal/day. Intensive agriculture practices such as the ones we will employ significantly improve on the figures, reducing the needed area to 48 m2 (480 square feet) (Salisbury & Bugbee). Our design is based on planting 60 m2 (600 square feet) of growing area to provide enough food to support one person. We will have about 80 m2 (800 square feet) available by using shelves and hanging pots.
Species selection is regarded as evolutional. That is, we will start with a variety and by subtracting those species that are unproductive, while adding others, we expect to conclude our experiments with a significantly different mix of species.
Initially we will start with wheat as our principal crop. Common garden vegetables such as carrots, peas and broccoli will supplement the diet. Other starches will be grown such as oatmeal, rice and other grains, along with beans and potatoes. For variety's sake we will also try a number of fruits, such as grapes and strawberries.
Many people propose using hydroponics for CELSS applications. This is certainly a viable option for space applications. However it is difficult to develop the hydroponics fluids in a truly closed system, so Mars Base 0 will not use many, if any hydroponics.
Our principal scientific goal for Mars Base 0 is to develop the subsystem interconnections that will be needed to build a completely closed ecological life support system. For example, the wheat straw will feed the earthworms that will feed the fish that will feed the humans. (Naturally a few hardy soles will cut out the fish factor and eat the earthworms directly.) We have experimented along this line, but our facilities have always been limited. So while we know many of our ideas are feasible we do not know if they are efficient. We do not expect to achieve full closure with Mars Base 0. If we can produce 60-80% of the calories needed to support one person we'll have a successful project. Oxygen, carbon dioxide and nitrogen will be more difficult to balance, and this may not prove possible with our imperfect seal. But we will track these gasses closely, and will be able to determine problem areas even if we can't balance them.
Food production is our focus. What are the best crops? Can we deal with pests adequately? How can we interrupt the (food chain) energy cascade, re-routing it to our principal consumer: a human? What are the most efficient sources of protein? What volume is needed to support a person? What kinds of environmental controls will we need to optimize food production? How can we reduce labor requirements? What can we do to improve the diet (from the inhabitant's point of view)?
During the winter months, when sealed operation is possible, we can also address problems such as optimum atmospheric mix, deleterious gas removal and humidity control. Other issues that will face both a Martian CELSS and winter operation of Mars Base 0 include temperature control, light production and heat conservation.
The similarities between the Alaskan and Martian environment will allow us to build a CELSS with many of the features required for a Martian CELSS. We will be able to investigate the lighting and power needs, many of the ecological design considerations and get an idea of the heating and cooling needs for a Martian CELSS.
Unfortunately there are a number of considerations we won't be able to address. Structure, gravity and year length are some of the more serious. However the data we shall generate will be sufficient to design a semi-open CELSS for use on Mars. Such a CELSS would rely on local materials to form the basis of the ecosystem. Neither air nor soil need be imported-only a structure and possibly some nutrients.
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Hamilton, Calvin J. http://www.hawastsoc.org/solar/
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