Species and Media Testing for the Veggie Plant Production System for Space

VEGGIE is a small space vegetable production system developed as a portion of a NASA Small Business Innovative Research (SBIR) grant that is designed for flat stowage and deployment in space.  VEGGIE could supply fresh foods to the astronauts and provide valuable test data for future bioregenerative life support technologies.  The system provides 0.13 m² of growing area and can operate in 1g, fractional g, and microgravity with variety of small plant species.   VEGGIE hardware consists of an LED light cap, a transparent extendable bellows for increased humidity, and a reservoir with a capillary wicking surface.  After testing a number of different direct and plug seeding options for planting, a rooting “pillow” concept was designed.  Pillows consists of small bags of media with a hydrophilic wicking surface, tubing for initial wetting, and slits containing wicks for seed placement and seedling emergence.   Time-release fertilizer is mixed with the media and capillary wicking draws water to pillows from the reservoir.  Pillows would be single use and could be launched into space dry, with seeds pre-planted. Preliminary tests examined different rates and formulations of time release fertilizer for  growth of lettuce cultivar ‘Outredgeous’, and Nutricote fertilizer (18-6-8) at a rate of 7.5 g / L dry media was selected for further analysis.  Testing also compared 1-2 mm arcillite media to a commercial peat-based media and both allowed excellent root production and distribution.  Further examination of media has been done, with comparisons of arcillite, commercial peat-based media, different ratios of the two, and a perlite: vermiculite mix.  Additional species have also been tested, including  ‘Flandria’ lettuce, ‘Oak leaf’ lettuce , ‘Sierra’ lettuce, mizuna, ‘Tender leaf’ vegetable amaranth, ‘Bright lights’ Swiss chard, ‘Tokyo Bekana’ cabbage, ‘Sugar Pod II ‘ snow pea, ‘Spicy Globe’ basil,  ‘Genovese’ basil , Common chives and Greek oregano.    Interesting differences were observed, with crops such as cabbage growing more rapidly in arcillite, while others, such as basil, are inhibited in arcillite compared to peat-based media.  Lettuce seems to grow best in a mixture of peat and arcillite.   Tested species and cultivars were selected based on their reported heat tolerance, as VEGGIE hardware operates at ~3°C above ambient temperature, as well as flavor when consumed raw, small plant size, high productivity, and capability for repeated harvest.