In a study conducted to evaluate low-gravity capabilities of life support components and processes of the Langley Research Center Integrated Life Support System (ILSS), primary emphasis was placed on:
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1.
Identification and analysis of gravity sensitivities inherent in performance of ILSS components and processes.
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2.
Investigation of methods for experimentally evaluating critical items for which zero-gravity performance could not be determined by analytical techniques.
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3.
Formulation of generalized criteria for assessing gravity sensitivity of alternate or advanced life support processes as well as those originally incorporated in the ILSS.
Of 92 ILSS processes identified, the majority were of such nature that their g sensitivities could be satisfactorily assessed by analyses, precluding the need for extensive testing.
Experiments included gravity-sensitive aspects of liquid droplet release, heat exchanger passage plugging, and liquid film stability. The investigation of experimental methods included a detailed review of low gravity and gravity related test techniques and an evaluation of the application of the methods to the test candidates.
The utility of analytical techniques in assessing gravity effects on performance became apparent in screening studies. Consequently, the development of these techniques was expanded beyond the immediate needs of the ILSS into generalized analytical approaches applicable to basic processes which may be common to most foreseeable life support systems. Processes considered in this phase of the study included heat transfer between fluids and solids; liquid behavior control by gas flow, capillarity, and centrifugation; solids control by gas flow; fluid mixing; mechanical device operation; and flame propagation.