Modeling the gas flux from the surface of Mars

Abstract

Results of preliminary calculations to a more comprehensive model forthe surface of Mars will be shown. The results are calculated for thesouth pole area and the equatorial area of the "red planet". Our new program, called CAPS, solves the time-dependent mass and energy equations for the different volatiles simultaneously. Solar energy input varies due to orbital and rotational motion of the planet. Heat is transferred into the interior of the body by solid state heat conduction in the ice-dust mixture (matrix) and by vapor flowing through the porous matrix. In our model we assume that the crust is always stable and cannot be destroyed by the escaping gas or impacts, but we allow atmospheric CO2 gas to condensate at the surface to build a frost layer if the temperature decreases below the sublimation temperature of CO2. We investigated the contribution ofthe vapor phases to the heat transport, calculated the gas flux from the surface into the atmosphere, and in case of a higher atmospheric pressure than the vapor saturation pressure we determined the condensation rate at the surface. The results depend on the composition of initially homogeneous body, the initial porosity, the initial pore radius, the the thermal conductivity of the solid ice matrix, and the tortuosity.