Life Sciences in the Space Program 



Phase III (1990-1992) will complete the testing and integration of all subsystems 

 into a true CELSS. Human consumption requirements and waste inputs will be 

 simulated. Atmospheric, biomass, and water cycles will be closed, and all 

 inputs outputs will be evaluated. Human testing will probably begin about 1995. 



Food Production and Processing. Issues that must be resolved in the food 

 production/processing area include: 



• Demonstrating large-scale and continuous biomass production using a 

 minimum of space and power 



• Finding the optimum balance between plant production and use of biomass to 

 meet human dietary needs 



• Testing to determine whether adequate supplies of plants can be continuously 

 produced in microgravity 



Using photosynthesis to convert light to consumable calories has been a main 

 thrust of CELSS research at ARC. Crop plants have been targeted initially as the 

 main mechanism for this conversion. Wheat can be grown at high density (2000 

 plants m ; ), with enriched CO, (1000 ppm) and high light (2000 micromol m : S) to 

 produce 56 g m : d 1 at >50 percent edible biomass, thus requiring a plant growth 

 area of 12 nv per person. Laboratory studies in potatoes have shown promise, 

 suggesting about 25 nf growth area required per person. Demonstration on a 

 large scale with continuous production has not yet been conducted. Verification of 

 laboratory studies is a major thrust of the KSC Breadboard Project, while the ARC 

 research program continues to define optimum conditions for plant growth and 

 photosynthesis efficiency. 



Algae and yeast systems have been studied extensively for biomass production, 

 and efficient cultural methods are available for both. Algae are efficient producers, 

 with 14- to 18-percent conversion that is possible during the logarithmic growth 

 phase. Furthermore, 25 percent or more of algal biomass can be extracted as 

 protein, and the cellular content of algae can be controlled by altering growth 

 conditions. For example, stress conditions shift cyanobacterial metabolism favoring 

 increased glycogen production. Thus, algal extracts can contribute to a nutritionally 

 balanced diet. In general, however, it would be desirable to use a combination of 

 higher plants and algae in a CELSS for dietary balance and stability. 



At present, we have little experience in growing higher plants or algae under 

 microgravity Questions concerning the effects of the space environment, 

 particularly of microgravity and radiation, on plant growth and function must be 

 evaluated by flight experiments for CELSS candidate species through several lite 

 cycles to determine if a viable stock can be maintained. The NASA Space Biology 

 Program, which conducts microgravity research, has obtained some information on 

 cellular aberrations in microgravitv that may be due to radiation effects. It would 

 useful for this program and the < II SS Program to collaborate on microgravity 

 riments. 



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