A Matrix-Based Porous Tube Water and Nutrient Delivery System

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A Matrix-Based Porous Tube Water and Nutrient Delivery System

Morrow, R. C. / Bula, R. J. / Tibbitts, T. W. / Dinauer, W. R.

A system was developed which provides nutrients and water to plants while maintaining good aeration at the roots and preventing water from escaping in reduced gravity. The nutrient solution is circulated through porous tubes under negative pressure and moves through the tube wall via capillary forces into the rooting matrix, establishing a non-saturated condition in the root zone. Tests using prototypes of the porous tube water and nutrient delivery system indicate that plant productivity in this system is equivalent to standard soil and solution culture growing procedures. The system has functioned successfully in short-term microgravity during parabolic flight tests and will be flown on the space shuttle.Plants are one of the components of a bioregenerative life support system required for long duration space missions. In addition to being a food supply, plants can remove atmospheric carbon dioxide, release oxygen, and transpire water from the leaf surfaces that can serve as a source of potable water. Providing a favorable root environment for plants in a space environment is essential in maintaining the growth rates necessary for an effective life support system. Consequently, supplying water and nutrients to plant roots in a microgravity environment is a major concern in the development of space-based plant growing facilities.Several methods for providing water and nutrients to plants in a reduced gravity environment have been proposed and have been evaluated in ground-based, 1 g, conditions (Koontz et al., 1990; Schwartzkopf, et al., 1989; Dreschel and Sager, 1988; Wright, et al., 1988). Evaluation of the effectiveness of some of these concepts to provide water and nutrients to plants under reduced gravity conditions has been limited to parabolic flight experiments.