����������� Although some jobs will cater to the needs and wantsof the colonists, services and products will primarily drive the economy of�ther sold to earth.� Three primarysources of employment on �ther will be industries, research, and exploration.
����������� Thelocale of the colony makes possible many novel techniques and resources, someof which have not been discovered hitherto.Solar power, asteroid mining, space tourism, satellite construction, andscientific missions would all be easier to attain through the use of thecolony.
����������� Solarpower has been touted as the ultimate non-polluting alternative to theenvironmentally costly ways of generating electricity today.
The modular,self-deploying solar power satellites considered in NASA�s 1995 Fresh Lookstudy showed a significant cost decrease over the older models that had beenpreviously considered in the 1979 DOE-NASA study.
����������� Photovoltaicmaterials fall into two general categories: thick crystalline andthin-film.� Silicon and gallium arsenideare thick crystalline, while amorphous silicon and polycrystalline silicon arethin-film materials.
Mostphotovoltaic cells used today are made of single-crystal silicon.
Gallium arsenide(GaAs) is even more expensive than single-crystal silicon as gallium is morerare than gold, and arsenic requires careful handling.
Amorphoussilicon is a non-crystalline form of silicon and absorbs light moreeffectively, thus a thinner layer is required.Amorphous silicon is usually deposited onto a substrate usingfabrication techniques that are less expensive than single-crystal siliconmethods.� However, efficiencies are onlyaround 5-7%.
Polycrystallinethin-film technologies utilize the sequential deposition of materials onto asubstrate to provide an inexpensive and easily scaled method of producingphotovoltaic cells.� However,polycrystalline photovoltaic cells suffer from poor durability and lowefficiencies.
By stackingseveral different types of cells, a multi-junction cell can be produced, withthe topmost cells absorbing the high-energy light, while the bottommost cellsabsorb the low-energy light.� Commonly,gallium arsenide is used as all or some of the component cells, but amorphoussilicon and copper indium diselenide component cells have also been used [ref37].� Multi-junction or cascade cellsprovide great design flexibility, achieve higher efficiencies, and offergreater resistance to radiation.Naturally, they are more expensive as they require more complex fabricationtechniques.
����������� Concentratorlenses can also raise power output as the cell is receiving stronger lightintensities.� However, they pose therisk of overheating the cell, and thus reducing efficiencies and destroyinglong-term stability.� The lenses mustalso be precisely aligned with the sun�s rays, otherwise they would be focusingthe light onto an unwanted point [ref 37].
����������� Thetechnology of choice to use for solar power satellites and for power generationon the colony seems to be crystalline silicon with concentrators.
����������� Probablyone of the most important parts of a SPS system is the method by which powerwill be transmitted from the SPS to the paying customer.
The AmericanNational Standards Institute dictates that the general populace should not beexposed to more than 10 mW/cm2 of microwave intensity, and currentdesigns for solar power satellite microwave transmission utilize a microwavebeam that possesses an intensity of 23 mW/cm2 and an intensity of0.1 mW/cm2 at the beam fringe [ref 9, 38].� The ground-based antenna could be constructed so that light canstill pass through, and the area directly underneath could be used for cropgrowing.� Birds and animals passingthrough the beam would experience only a slight heating, which would become anissue only on hot days.
����������� Miningand processing the lunar soil and rocks for valuable metals would be easy sincethe infrastructure for such tasks would already be required for constructingthe colony.� Augmenting and maintainingthe existing facilities would be even easier than the task of establishing thelunar base, since by then a highly productive and accessible manufacturingcenter would be in place at �ther and on the moon.� Large-scale exploration and exploitation of lunar resources wouldbe made possible by a permanent presence on the moon, and different lunar baseswould be established to harvest the local minerals.� Expeditions to the lunar poles where ice is suspected to haveaccumulated would also be feasible, and may simplify many life support andmanufacturing needs.� Helium-3 depositedby solar winds can also be harvested and utilized in experimental fusionreactors.� Self-contained mobile units,which extract volatiles from the lunar crust and store them in pressurizedtanks, have been designed and could potentially gradually build up thestockpile of helium-3 needed for fusion.
����������� Theasteroids that would be of main interest to asteroid-mining colonists would bethe Aten, Apollo, and Amor asteroids that have orbits close to the earth.
����������� Methodsof extracting those valuable ores and materials from asteroids would differbased on the type of asteroid.� If theasteroid 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 convenientlocations.� If the asteroid isundifferentiated, then some chemical processes similar to those used forextracting metals from lunar soil and rocks might be required before thedesired substances can be acquired.Volatiles could be extracted using lightweight solar ovens that focussunlight and then stored cryogenically.These volatiles would include N2, which would be integratedinto �ther�s atmosphere or used for a future space colony; H2 usedfor fuel; O2 used for oxidizer in chemical rockets or in habitableatmospheres; 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 movedto the asteroid, and processed materials periodically sent back to �ther, themoon, or the earth.� Asteroid miners (orasteroid-mining robots) could be like parasites moving from asteroid toasteroid and devouring them piece-by-piece.Metal extraction and refinement in space could be of great benefit toearth�s environment, as earth-bound processes release much sulfur into the air,which in turn causes many pollution problems.
����������� Tourismis centers around the idea of buying an unforgettable experience.
����������� Launchingsatellites from the colony would result in lower costs, as less fuel would beneeded to maneuver them into their final orbits.� Also, satellite construction would not have the restrictionsplaced on them by the use of earth-based launch vehicles; they would not haveto withstand the large forces exerted on them during liftoff and they would notbe limited to the payload capacity of the launch vehicle, thus eliminating theneed for modularization of the satellite and costly multiple launches.
����������� Largecommunications satellite constellations in low earth orbit would be able to providemany services to earth-bound humans, and they would have many advancements overcurrent satellites, including a stronger transmitter, larger antennae, betterheat rejection capabilities, increased intrasatellite communications abilities,better stationkeeping abilities, and more radiation shielding [9].
V.B Research
����������� In the exotic environment of microgravity, many importantexperiments 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 analyzingthe behavior of normal processes in microgravity, knowledge about how gravityimpacts those processes can be derived, and thus methods can be devised andimplemented on earth to counter the negative effects of gravity.
V.C Exploration
����������� Exploration of the Solar System and the universebeyond Pluto will be greatly accelerated by the construction of �ther.
Curator: Al Globus If you find any errors on this page contact Al Globus. |
This site was hosted by the NASA Ames Research Center from 1994-2018 and is now hosted by: