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The use of composting technology is attractive to NASA’s Bioregenerative Life Support System (BLSS) research because it offers a potential reduction in system costs when compared to other waste recycling approaches. Water-soluble leachates from 28-day composted fresh or oven-dried inedible wheat biomass were amended with reagent-grade nutrients to be inorganically equivalent to ½-strength Hoagland’s (control) replenishment solution. A portion of the fresh and oven-dried compost leachate was filtered to remove large organic particles and a majority of the microflora, and wheat plants were grown hydroponically on these amended leachates. For both the fresh and oven-dried compost leachate treatments, filtering the leachate had no effect on plant response. No significant difference was observed between the fresh compost leachate treatments and the control.

A primary challenge for supporting plants in space is to provide as much photosynthetically active radiation (PAR) as possible, while conserving electrical power. Light-emitting diodes (LEDs) and microwave lamps are innovative artificial lighting technologies with several appealing features for supporting plant growth in controlled environments. Because of their rugged design, small mass and volume, and narrow spectral output, red and blue LEDs are particularly suited for outfitting plant growth hardware in spaceflight systems. The sulfur-microwave electrode-less high-intensity discharge (HID) produces a bright broad-spectrum visible light at a higher electrical conversion efficiency than conventional light sources. Experiments compared the performance and productivity of spinach (Spinacia oleracea L.) grown under conventional lighting sources (high-pressure sodium and cool-white fluorescent lamps) with microwave lamps and various wavelengths of red LEDs.