Here on earth, researchers still debate how best to make those possible, but nuclear-powered state of the art LED (Light-emitting Diode) technology is arguably what will drive photosynthesis so necessary to provide both food and oxygen for future lunar colonists.
Future long-term lunar residents will need to grow their food either in sub-lunar lava tubes or in greenhouses shielded with several meters of lunar surface regolith. With no atmosphere, the moon is regularly exposed to lethal doses of cosmic rays, solar coronal mass ejections and x-flares, not to mention micro-meteorites that would be enough to wreck anyone’s corn.
Although during the two weeks that make up the long lunar day astronauts might be able to funnel refracted sunlight into covered greenhouses or subsurface lava tunnels, they will be left without a light source during the long lunar night.
Current solar-powered battery storage technology isn’t adequate to sustain artificial light sources for two weeks at the time. Thus, the most practical solution is simply to use some sort of Radioisotope Thermoelectric Generator (RTG), not unlike the one powering the current Mars Science lab, to power the LEDs that will spur photosynthesis in lunar greenhouses.
Cary Mitchell, a plant biologist at Purdue University, says that as lunar light sources, LEDs would be cool, solid state and robust; lasting 50,000 hours at least, or some five times longer than conventional horticultural light sources. He also notes that that they could survive the journey to the lunar surface where they could then be strung inside inflatable lava tunnel greenhouses or in radiation-hardened, solid greenhouses on the surface.
On earth, Mitchell says it takes roughly 50 square meters of agriculture to provide both food and oxygen life to support one human. But, as he points out, who can say how productive plants are ultimately going to be on the moon, in gravity that is only one sixth that of earth?"
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