Search Results

Regenerative life support is considered a key enabling technology for the human exploration of space. Without regeneration, the cost of supplying the materials necessary to sustain human life escalates so rapidly that manned space flight becomes uneconomical for all but short, near-Earth missions. One of the methods for providing regenerative life support utilizes a Controlled Ecological Life Support System, or CELSS. To accomplish this regeneration, the CELSS must incorporate technologies for food production, food processing, atmospheric revitalization, water purification, trace contaminant control, and waste processing. Many experiments have been conducted to characterize the performance of individual CELSS subsystems (e.g., plant growth, waste processing). However, very little research has been done to define the performance and operational aspects of CELSS technology at the overall system level.

Little information exists on the responses of plants to environmental conditions which combine lower than Earth-normal atmospheric pressures with changes in the partial pressures of oxygen, carbon dioxide, and nitrogen. Data collected on the growth of plants in such environments will be valuable in the development of low-pressure plant growth facilities for use on Space Station Freedom, the moon, and Mars. Such low pressure environments have been proposed previously as a means of facilitating EVA operations. Additionally, in some planetary base applications, the use of low atmospheric pressure would allow the use of lightweight plant growth structures for food production, thus reducing both the mass and the launch cost of the life support system.

A closed-loop, regenerative life support system must include a method for recycling organic waste materials. With a Controlled Ecological Life Support System (CELSS), this will be accomplished by decomposing the wastes and using the effluent to formulate a nutrient solution which supports food production by plants. The waste processing technology used may be either physicochemical or biological. Although the effluents from biological processors have been extensively evaluated as fertilizers for soil-based agricultural systems, few experiments have been conducted to evaluate their suitability in hydroponic applications. This paper describes the results of a series of experiments performed to evaluate effluent from an anaerobic bacterial reactor as a nutrient source for hydroponically-grown plants. Germination and initial seedling growth were found to be suppressed by pure effluent.

The Space Transportation System uses a triiodide quaternary ammonium strong base resin to prevent microbial contamination of the crew's drinking water. Current plans for Space Station Freedom use the STS resin for microbial control in drinking water. Another use for this water is in the “salad machine” to grow vegetable plants hydroponically. Our experiments demonstrate that leaf lettuce (Lactuca sativa) grown in nutrient solution treated with the triiodide resin and it's next higher homologue, pentaiodide, result in greatly reduced growth or death. The triiodide and pentaiodide treatments reduced plant fresh weights to 0.2% and 0.04% of the controls respectively. Tissue analysis by neutron activation showed an iodine concentration of 0.47% to 0.6% in the experimental plants. Nutrient solution analysis showed an average residual concentration of 38 and 65 mg/l iodine at the end of the 30 day experiments for triiodide and pentaiodide treatments respectively.