Mayumi Arai

An overview of challenges in modeling heat and mass transfer for living on Mars.

Abstract:  Engineering a life‐support system for living on Mars requires the modeling of heat and mass transfer. This report describes the analysis of heat and mass transfer phenomena in a greenhouse dome, which is being designed as a pressurized life‐support system for agricultural production on Mars. In this Martian greenhouse, solar energy will be converted into chemical energy in plant biomass. Agricultural products will be harvested for food and plant cultivation, and waste materials will be processed in a composting microbial ecosystem. Transpired water from plants will be condensed and recycled. In our thermal design and analysis for the Martian greenhouse, we addressed the question of whether temperature and pressure would be maintained in the appropriate range for humans as well as plants. Energy flow and material circulation should be controlled to provide an artificial ecological system on Mars. In our analysis, we assumed that the greenhouse would be maintained at a subatmospheric pressure under 1/3‐G gravitational force with 1/2 solar light intensity on Earth. Convection of atmospheric gases will be induced inside the greenhouse, primarily by heating from sunlight. Microclimate (thermal and gas species structure) could be generated locally around plant bodies, which would affect gas transport. Potential effects of those environmental factors are discussed on the phenomena including plant growth and plant physiology and focusing on transport processes. Fire safety is a crucial issue and we evaluate its impact on the total gas pressure in the greenhouse dome.

Linear baroclinic instability in the Martian atmosphere: Primitive equation calculations

In this study, baroclinic-barotropic instability of the Martian atmosphere is studied for a zonal basic state based on Mariner 9 observations, using a spherical linear primitive equation model derived from a method of 3-D normal mode expansion. As a result of solving a matrix eigenvalue problem, a distinctly unstable mode at synoptic to planetary scales was found with a peak growth rate of 2.3 (1/sol) at zonal wavenumbers n = 5 to 6 with an eastward phase speed of 50 (°/sol). The unstable mode has a period of 2.4 sol for n = 3, which agrees well with Viking observations. The geopotential amplitude maximum is located at 50°N near the surface, and the phase tilts westward with height. The structure is similar to baroclinic instability of a Charney mode associated with the subtropical jet on Earth. It is found, however, that the mode on Mars, where the subtropical jet is absent, is not the ordinary Charney mode, but a different one that is referred to as a monopole Charney mode in previous study which is characterized by its overall northward eddy momentum flux.