Title
Adapting a Mars ISRU System to the Changing Mars Environment
AbstractÂ
This study modeled the performance of a full-scale Mars in situ resource utilization (ISRU) system to produce 30 metric tons of liquid O2 , operated for 14 months at half-hourly intervals as the Mars environment changes diurnally and seasonally. We considered various control options, with particular emphasis on power requirements and required cell voltages. Mars temperature and pressure data at half-hour intervals were obtained from the Mars Perseverance team. The full-scale Mars ISRU system included a mechanical compressor, high-temperature electrolysis of Martian CO2 , and a liquefier to produce liquid oxygen. The key factors were (a) maintaining cell voltage well below the Nernst potential for carbon formation from CO2 and (b) tracking the maximum power, as well as the range of power required, at each half-hourly junction across the 14-month run for each control option. The most favorable control option involved adjusting the compressor revolutions per minute at each half-hour to produce a quasi-steady state of oxygen production in the electrolysis and the liquefaction systems, resulting in the most benign electrolysis settings, the lowest maximum power, and the narrowest range of required power. Other approaches where the compressor was run at a steady state and the oxygen production rate varied with time led to higher electrolysis voltage, higher maximum power, and a wider range of power. This study provides guidance on the optimum operating conditions and power requirements of a Mars ISRU system to produce 30 metric tons of liquid oxygen in 14 months of operation.