A hybrid propulsion system for a vehicle comprises a propellant tank for providing a supply of propellant, a propellant heater, and an exhaust nozzle. The propellant tank is in fluid communication with the propellant heater and is configured for providing a flow of propellant to the propellant heater. The propellant heater is in fluid communication with the propellant tank and the nozzle and initially comprises a supply of oxidizer that is configured for reacting chemically with the propellant to produce heat. The propellant heater is further configured for receiving a beam of microwave energy and facilitating transmission of the beam of microwave energy to the propellant. The nozzle is in fluid communication with the propellant heater and is configured for receiving a flow of propellant from the propellant heater, for accelerating the propellant, and for expelling the propellant so as to produce thrust.