ELECTRIC LIGHTING CONSIDERATIONS FOR CROP PRODUCTION IN SPACE

Requirements of plant lighting systems for biological life support in space are based on a number of factors including spectral quality for plant growth, energy conversion efficiency, cost, reliability, durability, and equipment mass. Many light sources, from electric lamps to solar radiation, have been evaluated for this type of controlled environment applications. Among the technologies tested, sulfur-microwave electrode-less (microwave, MW) lamps and light-emitting diodes (LEDs) have a high potential for application in advanced life support systems. The MW lamps are efficient and provide a broad spectrum, but the technology needs to distribute the point-source light evenly over a plant canopy and more durable microwave or radio frequency generators need to be developed. The LEDs offer a solid state framework and a long operating life, and continue to advance in terms of efficiency, available wavelengths, output, cost, and application methods. Many biologists are taking advantage of the unique characteristics of LEDs to study the effects of spectral quality on plant growth and development. Growing plants in space will be a vital part of future life support systems where the development of a highly optimized biomass production system is critical to the Exploration Vision of NASA. The latest technologies need to be evaluated and integrated with life support systems as they develop and evolve to further optimize the most cost-effective and reliable systems for space.