Abstract: Bi-modal propulsion systems and related methods are generally described. In some embodiments, a bi-modal propulsion system may employ a single propellant for both chemical thruster(s), operating at elevated pressures, and electrical thruster(s) (e.g., electro spray thruster), operating at reduced pressures. The propellant pressure may be reduced to a desired operational range of the electrical thruster(s) using any appropriate construction including, for example, capillaries configured to reduce the pressure of the propellant to an operational range of the electrical thruster(s). In some embodiments, the reduced pressure of the propellant may be lower than a vapor pressure of at least one volatile component of the propellant, leading to the formation of “bubbles” within the propellant line. The presence of alternating gas and liquid phases along a flow path between a propellant tank and the electrical thruster(s) may help to electrically insulate the electrical thruster from the rest of the system.