Dry ice propulsion system for ISRU and removal of terrestrial CO2

This study proposes dry ice as an alternative propellant suitable for in-situ resource utilization considering its abundance in the Martian atmosphere and availability from human respiration. For large-scale satellite constellations, loading CO2 onto Earth and consuming it in space supports both carbon utilization and removal from Earth. The thermodynamic equilibrium of the CO2 triple point (0.518 MPa, 217 K) allows for low-pressure storage, reduces the tank mass, and enables a constant pressure and constant flow rate supply, thereby simplifying propulsion systems. A novel approach is introduced in which the phase change within the tank is controlled by balancing the external heat input with the enthalpy of the vapor supplied to the thruster. As a representative configuration, an integrated system combining Hall thrusters with cold-gas jets is proposed. Key challenges include low-temperature tank thermal management, control of three-phase distribution under microgravity, improvement of propellant utilization in CO2 Hall thrusters, and the development of low-power CO2-compatible cathodes. This paper presents both ground-based and on-orbit operational scenarios and summarizes the ongoing efforts to address these challenges.