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It is understood that plants and microorganisms will be an intrinsic part of future advanced life support (ALS) systems. The photosynthetic process is uniquely able to provide food and water from transpiration, remove carbon dioxide, and produce oxygen. However, atmospheric management with typical monoculture batch plant growth is made difficult due to fluctuating rates of CO2 assimilation and O2 production during different phases of plant growth and development. Experiments on the effect of continuous production of multiple crops with rotational planting on atmospheric stability within a sealed environment were performed in the Controlled Environment Systems Research Facility ambient pressure controlled environment chambers. Two of the ESA-MELiSSA candidate crops, beet and lettuce, were continuously grown with a ten day staggered planting interval, resulting in a plant canopy with all representative stages of physiological growth within a common atmosphere.

Mars is likely the best candidate for future planetary exploration however the Martian atmosphere is at a pressure of ~0.6 kPa. This extremely low pressure demands that plant growth structures be isolated from the ambient environment. While it is clear that it is desirable to predict the contributions that plants will make to bioregenerative life support systems at reduced atmospheric pressures, research has been limited. This study examines carbon exchange and evapotranspiration in order to establish a baseline that will aid in the development of an atmospheric composition that allows for reduced pressure plant growth without compromising the plant production yields required for human life support.

Due to its large proportion of edible biomass, beet (Beta vulgaris) has high potential as a candidate crop for bioregenerative life support systems. This paper summarizes data collected for beet under batch and staged stand culture in closed environment chambers. Full stand trials were conducted under the following conditions: 1000 μL L−1 atmospheric carbon dioxide concentration, light intensities ranging from 400–600 μmol m−2 s−1 PAR with a 14 hour photoperiod, 73% ± 5% relative humidity, a 26/20 °C day/night temperature regime and a fixed planting density of 17.6 plants m−2. For batch planted stands, total edible yield was determined to be 28.3 g dry weight basis (dwb) with a 95% Confidence Interval (CI) of [24.7, 31.8] g plant−1 with a harvest index of 94%. Under similar conditions, yield for staged beet stands was 31.4 g dwb with a 95% CI of [24.54, 38.31] g plant−1. Water use efficiency under these same conditions was found to be 0.003 mol C mol−1 H2O.