Although some jobs will cater to the needs and wants of the colonists, services and products will primarily drive the economy of Æther sold to earth. Three primary sources of employment on Æther will be industries, research, and exploration.
The locale of the colony makes possible many novel techniques and resources, some of which have not been discovered hitherto. Solar power, asteroid mining, space tourism, satellite construction, and scientific missions would all be easier to attain through the use of the colony.
Solar power has been touted as the ultimate non-polluting alternative to the environmentally costly ways of generating electricity today. While some pollution would be released into the atmosphere as a result of photovoltaic (PV) cell fabrication and launch of solar power satellites, these concerns could easily be side stepped if PV cell fabrication occurred in outer space, where the pollution would not harm terrestrial life. Compounding the problem of pollution from existing power plants is the fact that global power demand is rising. Population is growing at the same time per capita energy use is growing, thus the global environment bears the brunt of ever escalating pollution. Modern power plants produce many types of pollution, coal-fired power plants release carbon dioxide, sulfur oxides, and a host of other toxic metals including some radioactive isotopes into the air; nuclear power plants do not release much pollution, but there is the problem of long-term storage of nuclear wastes associated with it. While wind-driven power plants and other alternative sources of power are coming into use, the predominant means of power generation is the combustion of fossil fuels.
The modular, self-deploying solar power satellites considered in NASA’s 1995 Fresh Look study showed a significant cost decrease over the older models that had been previously considered in the 1979 DOE-NASA study.
Photovoltaic materials fall into two general categories: thick crystalline and thin-film. Silicon and gallium arsenide are thick crystalline, while amorphous silicon and polycrystalline silicon are thin-film materials.
Most photovoltaic cells used today are made of single-crystal silicon. Single-crystal photovoltaic cells require a source of 99.9999% pure silicon, which are grown into ingots; wafers are then sliced from this ingot and used for constructing the different parts of the cell.
Gallium arsenide (GaAs) is even more expensive than single-crystal silicon as gallium is more rare than gold, and arsenic requires careful handling. However, the benefits are enormous, as GaAs cells can reach efficiencies of 25-30%, are insensitive to high temperatures, have high absorptivity, are immune to radiation damage, and can have their characteristics precisely controlled by adding aluminum, phosphorus, antimony, or indium.
Amorphous silicon is a non-crystalline form of silicon and absorbs light more effectively, thus a thinner layer is required. Amorphous silicon is usually deposited onto a substrate using fabrication techniques that are less expensive than single-crystal silicon methods. However, efficiencies are only around 5-7%.
Polycrystalline thin-film technologies utilize the sequential deposition of materials onto a substrate to provide an inexpensive and easily scaled method of producing photovoltaic cells. However, polycrystalline photovoltaic cells suffer from poor durability and low efficiencies.
By stacking several different types of cells, a multi-junction cell can be produced, with the topmost cells absorbing the high-energy light, while the bottommost cells absorb the low-energy light. Commonly, gallium arsenide is used as all or some of the component cells, but amorphous silicon and copper indium diselenide component cells have also been used [ref 37]. Multi-junction or cascade cells provide great design flexibility, achieve higher efficiencies, and offer greater resistance to radiation. Naturally, they are more expensive as they require more complex fabrication techniques.
Concentrator lenses can also raise power output as the cell is receiving stronger light intensities. However, they pose the risk of overheating the cell, and thus reducing efficiencies and destroying long-term stability. The lenses must also be precisely aligned with the sun’s rays, otherwise they would be focusing the light onto an unwanted point [ref 37].
The technology of choice to use for solar power satellites and for power generation on the colony seems to be crystalline silicon with concentrators. Since silicon is abundant on the moon and crystals with few imperfections can be grown in microgravity, crystalline silicon cells would give the maximum efficiencies at acceptable costs. The concentrators can be fashioned out of lunar silicon and can be coated with thin layers of selectively transparent materials, so that the cells are shielded from unnecessary radiation that would cause heating. Solar power satellites may contain longer-lasting gallium arsenide cells if longevity is of concern, but since the cells used for colony power generation can be easily replaced, less durable cells that are more economic may be used.
Probably one of the most important parts of a SPS system is the method by which power will be transmitted from the SPS to the paying customer. Microwave provides the most efficient method of power transmission, with recent transmission loss rates of only 18% [ref 25]. In the scheme envisioned by NASA engineers, the solar power satellites would be outfitted with microwave transponders, which would beam the energy to earth, where a large antenna would receive it. This system ideally would produce no waste matter, no sulfurous emissions, and no greenhouse gasses. Construction of the large antenna could take place in isolated or offshore areas relatively close to the markets it serves so as to reduce electric transmission losses, and all that is needed is to wire them into the existing electrical grid. By using select microwave frequencies around 2.45 GHz, absorption of energy by water vapor and air can be avoided [ref 9]. Since microwave radiation is non-ionizing and possesses less energy than sunlight, radiation effects, such as increased risk of cancer, damage of genes in sex cells, and massive death of somatic cells, commonly associated with high-energy electromagnetic waves and heavy nuclei would not be present. Thus the only effect of the microwave beam would be the heating of the object inside the beam. There is however, growing concern over the “Microwave Effect,” which seems to show that microwaves can indeed break the covalent bonds inside DNA due to the formation of free radicals [ref 39].
The American National Standards Institute dictates that the general populace should not be exposed to more than 10 mW/cm2 of microwave intensity, and current designs for solar power satellite microwave transmission utilize a microwave beam that possesses an intensity of 23 mW/cm2 and an intensity of 0.1 mW/cm2 at the beam fringe [ref 9, 38]. The ground-based antenna could be constructed so that light can still pass through, and the area directly underneath could be used for crop growing. Birds and animals passing through the beam would experience only a slight heating, which would become an issue only on hot days.
Mining and processing the lunar soil and rocks for valuable metals would be easy since the infrastructure for such tasks would already be required for constructing the colony. Augmenting and maintaining the existing facilities would be even easier than the task of establishing the lunar base, since by then a highly productive and accessible manufacturing center would be in place at Æther and on the moon. Large-scale exploration and exploitation of lunar resources would be made possible by a permanent presence on the moon, and different lunar bases would be established to harvest the local minerals. Expeditions to the lunar poles where ice is suspected to have accumulated would also be feasible, and may simplify many life support and manufacturing needs. Helium-3 deposited by solar winds can also be harvested and utilized in experimental fusion reactors. Self-contained mobile units, which extract volatiles from the lunar crust and store them in pressurized tanks, have been designed and could potentially gradually build up the stockpile of helium-3 needed for fusion.
The asteroids that would be of main interest to asteroid-mining colonists would be the Aten, Apollo, and Amor asteroids that have orbits close to the earth. These asteroids contain many desirable materials, such as water, methane, iron, nickel, cobalt, and many other substances that would garner high prices in today’s market. In fact, about half of the nickel used today comes from an asteroid’s impact crater. Also, rare platinum and platinum-group metals are also present in asteroids and would fetch high prices in earth markets. Nonmetals such as gallium, germanium, and arsenic would also be in demand in the semiconductor industry.
Methods of extracting those valuable ores and materials from asteroids would differ based on the type of asteroid. If the asteroid is differentiated, that is if it had formed when it was molten hot, the elements would be separate from each other and quite possibly in convenient locations. If the asteroid is undifferentiated, then some chemical processes similar to those used for extracting metals from lunar soil and rocks might be required before the desired substances can be acquired. Volatiles could be extracted using lightweight solar ovens that focus sunlight and then stored cryogenically. These volatiles would include N2, which would be integrated into Æther’s atmosphere or used for a future space colony; H2 used for fuel; O2 used for oxidizer in chemical rockets or in habitable atmospheres; and CO2, used for agriculture [http://www.seds.org/~rme/nea.htm]. Mass drivers similar to the one on the moon would then be built or moved to the asteroid, and processed materials periodically sent back to Æther, the moon, or the earth. Asteroid miners (or asteroid-mining robots) could be like parasites moving from asteroid to asteroid and devouring them piece-by-piece. Metal extraction and refinement in space could be of great benefit to earth’s environment, as earth-bound processes release much sulfur into the air, which in turn causes many pollution problems.
Tourism is centers around the idea of buying an unforgettable experience. Thus, the exotic locale of the colony makes it ideal for tourism. Space tourism has already begun on earth on a limited scale in the forms of MiG-25 flights and the like. However, before space tourism can really bring in significant revenue, space flights must have a safety record comparable to that of aviation. Fortunately, this goal would already be addressed since it is a prerequisite for colony construction. Tourist accommodations could be in the form of hotels inside the colony, or “cruise ships” that orbit around the moon and earth, offering spectacular views. Zero-g entertainment would also be a key “hook” for earth-based tourists. However, a CELSS designed for tourist use would have to take into account that most tourists would want more food, water, etc. than the average colonist. Specialty foods and beverages that could not be produced from the onboard CELSS would have to be imported from earth, making the price of such a hotel very expensive. Considering that people do pay exorbitant sums for cruises, such a space industry is not very far fetched.
Launching satellites from the colony would result in lower costs, as less fuel would be needed to maneuver them into their final orbits. Also, satellite construction would not have the restrictions placed on them by the use of earth-based launch vehicles; they would not have to withstand the large forces exerted on them during liftoff and they would not be limited to the payload capacity of the launch vehicle, thus eliminating the need for modularization of the satellite and costly multiple launches. Servicing of satellites that have broken down would also be much more cheaper than current methods that involve earth-based astronauts.
Large communications satellite constellations in low earth orbit would be able to provide many services to earth-bound humans, and they would have many advancements over current satellites, including a stronger transmitter, larger antennae, better heat rejection capabilities, increased intrasatellite communications abilities, better stationkeeping abilities, and more radiation shielding . These satellites would be able to provide mobile phone coverage, wireless internet services, and many other communications services.
In the exotic environment of microgravity, many important experiments can be carried out. Particular topics of interest are microgravity fluid dynamics, astronomy, protein synthesis, nanotechnology, vacuum research, biotechnology, microbiology, growth of imperfection-free semiconductor and metallic crystals, and materials processing. By analyzing the behavior of normal processes in microgravity, knowledge about how gravity impacts those processes can be derived, and thus methods can be devised and implemented on earth to counter the negative effects of gravity. Large telescopes can easily be constructed using lunar materials, and relatively little computation will be needed to correct for aberrations in the image, since there is no atmosphere in space to distort the image. Other data-gathering instruments, such as gamma ray, x-ray, radio, and microwave telescopes would also be scaled up and be able to benefit from interference-free observing.
Exploration of the Solar System and the universe beyond Pluto will be greatly accelerated by the construction of Æther. Instead of facing exorbitant launch costs, scientists can build a custom-designed probe or use a generic probe and send it far into the depths of space using maglevs that would accelerate them to the proper velocities. Probes would also not suffer the mass restrictions placed on them by conventional earth launches and thus would be able to record much more data in the same amount of time, since more instruments and larger radio dishes can be placed into a probe. Planets only given a cursory glance at the expense of millions and even billions of U.S. dollars would be thoroughly explored and analyzed, while planets and orbiting bodies never before explored would also enjoy a greater amount of attention.
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