Early Human Testing of Advanced Life Support Systems, Phase I 951490

The Crew and Thermal Systems Division (CTSD) at NASA's Johnson Space Center under the support of the Office of Life and Microgravity Sciences and Applications is conducting the Early Human Testing Initiave (EHTI) project with the goal of validating regenerative life support technologies through a series of integrated tests with human subjects. The EHTI project is organized into three distinct phases, each with progressively more complex integration of biological and physicochemical (P/C) life support technologies. The goal of Phase I is to conduct a 15-day one-person test to verify the performance of an air revitalization system based on higher plants with physicochemical systems as complements and backups. The test will be performed in CTSD's Variable Pressure Growth Chamber (VPGC), a tightly closed controlled-environment test chamber configured with approximately 11 m² of area for plant growth. A dense, actively-growing stand of wheat will be grown to provide a minimum of one human metabolic load of oxygen production and carbon dioxide removal through the process of photosynthesis. The test subject will reside in the chamber's air lock, which will be set-up with accommodations for habitation. The atmosphere will be recirculated between the airlock and growth chamber at a defined rate. Three different methods of gas composition control will be evaluated in series over a continuous 15-day period: 1) use of P/C systems and storage buffers to trim off differences in metabolic rate between the test subject and plants; 2) modulation of photosynthetic rate to match the test subject's metabolic load by active control of photosynthetic photon flux and 3) modulation of photosynthetic rate to match the test subject's metabolic load by limiting the amount of carbon dioxide available to the plants.