A team of physicists at the University of California, Irvine has found a short cut for efficient propellant production on Mars. The UCI researchers have discovered a way to streamline the conventional two step Sabatier process which first electrolyzes water into hydrogen before reacting with carbon dioxide in the Martian atmosphere to create methane. Both SpaceX and Blue Origin use methane in their rocket engine designs. The novel approach simplifies fuel production by leveraging zinc as a “synthetic enzyme,” which catalyzes carbon dioxide to synthesize methane directly. The improved process will reduce the amount of ISRU equipment (and therefore weight and launch costs) needed for transport to the surface of Mars to facilitate propellent production required for the trip home. The research has only demonstrated proof of concept so follow-on studies are required to improve the TRL for flight-ready hardware.
Propellant production on Mars
Early missions to Mars such as Robert Zubrin’s Mars Direct architecture will require propellant production for the trip home. Methane can be produced in situ on the red planet’s surface through the basic chemical reaction CO2 + 4H2 → CH4 + 2H2O. A French chemist named Paul Sabatier discovered back in 1897 that this reaction could be facilitated by a nickel catalyst in the presence of hydrogen and carbon dioxide at elevated temperatures. Since water ice is present on Mars, hydrogen could be produced though electrolysis of water. Combining these two reactions into a methane production system, Michel Lamontagne has provided a schematic of the whole process on marspedia.org. By design, the SpaceX Starship uses methane for fuel. The company may want to prioritize development of a flight-ready Sabatier reactor for this system to enable the transportation infrastructure needed for supplying a settlement until it can become self sufficient.