Solar Plant Growth System for Food Production in Space Exploration Missions

The proposed Solar Plant Growth System for Food Production is for application to: 1) onboard a crewed spacecraft such as the Deep Space Habitat or ISS where compact and efficient solar photosynthetic life support is required; and 2) a Lunar, NEO or Mars base where large scale food production and life support are implemented. The conventional concept for plant lighting is to employ electric lamps such as fluorescent, or high-pressure sodium (HPS) lamps or light emitting diodes (LED). With this conventional system concept, it is difficult to achieve high photosynthetic food production without causing unmanageable parasitic heat loading. For the proposed system, only the PAR spectra are delivered to the plant growth chamber by a compact flat lighting panel, thereby reducing most of the parasitic heat generation in the habitat. The proposed solar lighting system can also be utilized to supply solar thermal power to the habitat by changing the PAR mirror to the full spectral reflective mirror. Thermal power delivered to the habitat can be used for: habitat thermal control; manufacturing; and material processing. PSI has demonstrated such applications of the solar power system in our previous NASA program related to ISRU. The system concept discussed in this proposal has many other NASA applications such as material recycling such as nutrient re-use, and pollution removal from water (rhizofiltration) in human habitat.

The solar lighting system discussed in this proposal can be used for household, commercial or industrial lighting. In addition, industry and educational institutions that are currently using electric lamps for plant lighting will likely deploy the proposed system. In 2009, PSI developed a prototype solar lighting system for agricultural transplants with USDA SBIR funding. In this program we provided solar lighting within the protected transplant growing chamber. This technique can be applied to controlled production of pharmaceuticals using transgenic plants or specialized native plants. An interesting application of the optical fiber based (Optical Waveguide) solar lighting system is for "Vertical Farming." Vertical Farming' could provide fresh vegetables in urban areas in the off season, if an efficient light delivery system is available. To date, Vertical Farming with electric lighting has been limited by the inefficiency of solar photovoltaic cells and the associated low conversion efficiency of electric lights. By using the solar lighting system based on Optical Waveguide lighting, the deficiency of Vertical Farming can be eliminated. A solar based light delivery system would eliminate the need for the greenhouse and make all parts of the growth system highly productive. The work described in this proposal has the potential to fundamentally change our ability to produce fresh food from local suppliers on a year round basis. More »