Gas exchange in NASA's biomass production chamber: a preprototype closed human life support system.

TLDR

Monitoring and regulating atmospheric gases at life‑support‑critical concentrations is essential for environmental control in a life‑support system. The study aims to determine CO₂ usage, O₂ evolution, and water flux through evapotranspiration by a crop stand under various environmental conditions to design control systems that maintain gas mass balances across regimes. The chamber’s gas‑budget measurements allow crop health assessment via gas exchange rates and dry‑matter accumulation, and it uniquely monitors wheat and soybean exchange rates, the two NASA CELSS candidate species.

Abstract

An important aspect of environmental control in a life-support system is the monitoring and regulation of atmospheric gases (Sager et al. 1988) at concentrations required for the maintenance of all life forms. It will be necessary to know the rates of CO2 use, oxygen evolution, and water flux through evapotranspiration by a crop stand under various environmental conditions, so that appropriate designs and control systems for maintaining mass balances of those gases can be achieved for a full range of environmental regimes. Mass budgets of gases will also enable evaluation of crop health by monitoring directly the rates of gas exchange and indirectly the rate of accumulation of dry matter, based on rates of carbon dioxide use. This article focuses on the unique capabilities of the NASA biomass production chamber for monitoring and evaluating gas exchange rates, with special emphasis on results with wheat and soybean, two candidate species identified by NASA for CELSS.