View source for Lunar Polar Greenhouse

==A Lunar Polar Greenhouse== 
In economically rational development of lunar [[resources]], remotely controlled devices would be used to establish some industrial infrastructure before people would be sent to [[Luna]] in person.  Then the first employees would eat all imported food for some time.  Air and water would be recycled to a considerable extent with the loss of some locally produced [[oxygen]] being tolerated.  Human waste would be incinerated to recover water, [[carbon]] as [[carbon dioxide]] and other volatiles for industrial use. Hydrogen and perhaps some other volatiles would be mined from the lunar poles if practical but hydrogen and therefore water would still be rare and expensive on Luna.   
===Gardening Begins===
When the extent of development permits, this underground [[greenhouse]] could be built in a polar region.  It would require that the vast majority of materials be locally obtained.  The greenhouse would be built as a 100 meter diameter ring around a hill.  Then the top of the hill would be flattened enough to provide fill to bury the greenhouse 10 meters deep.  Mirrors would be used to concentrate sunlight and send it to the greenhouse through periscopes.  Sunlight would be dispersed in the greenhouse to the proper strength for plants.  Radiation composed of subatomic particles would not be reflected by the mirrors so the greenhouse would be protected.  Most ultraviolet light requires a special coating to be well reflected.  <ref> McGraw-Hill Encyclopedia of Science and Technology (c) 1997 article on "Telescope, Ultra Violet Telescope" </ref> So the periscopes would protect against ultraviolet also.  A glass window would provide further protection against ultraviolet.  Light would not shine on the intake mirrors of all periscopes at the same time, so crops would be grown on flat top rail road cars to shuffle them around to get eight hours of light every day for each rail road car during the growing season, which would be the local summer at the pole.  Since  light enters the greenhouse in concentrated form through a minority of the area of the walls and ceiling, it would provide sufficient heat for the greenhouse and the problem would be controlled cooling.  Radiators on top of the flat hill would cool the greenhouse as other industrial installations on Luna will be cooled.  Radiation of infrared can be indirect by reflection to protect the radiator from micrometeoroids.  
===The High Cost of Food===
The many considerations beyond what is required on Earth that must taken into account to start operating a lunar greenhouse will result in expensive food.  It only needs to be cheap enough to compete against food imported from Earth, and that is worth its weight in gold.
===Reference===
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[[category:Agriculture]]