Analysis of Mg-CO2 Rocket Propulsion for a Mars Ascent Vehicle exploiting in situ resources

A key technology that would make possible to achieve human martian exploration is In Situ Resources Utilization(ISRU). Typical ISRU proposals are based on propellants production by processing martian atmosphere. As measured by Viking landers, the lower martian atmosphere is composed by 95.32% of CO2. Seeing the abundance of CO2, the simplest ISRU approach would be to use it directly as an oxidizer without the need of power costing chemical processing. Shafirovich compared various metals and their hydrates as possible fuels and concluded that magnesium is the most promising one. Viking landers analyzed also martian regolith finding that 8.6% by mass consists of MgO, opening the opportunity to produce all the propellant, both the oxidizer and the fuel, in a future martian base. This opportunity led to the proposal and testing of two types of Mg − CO2 rocket engines: a powder Mg - CO2 one, and an hybrid rocket engine with a paraffin wax-Mg fuel grain and a mixture of CO2 − N2O as oxidizer. These two engines are described in the initial chapthers of the thesis. A simplified model is then proposed to estimate the performances of a Mars Ascent Vehicle as functions of the oxidizer to fuel ratio, stages properties, propellant properties and mass fractions sent from Earth. The model is then applied to the two proposed Mg-CO2 rocket configurations to estimate their performance and verify the convenience of CO2 collection on Mars.