high delta V over shorter periods. Physical Principles Resistojets can be considered an evolution of traditional cold gas thrusters, which are the simplest form of rocket engine available. Their fuel tank holds the propellant, which is then led into the nozzle where it decompresses, propelling the craft forward. In a resistojet, a resistor is used to heat the fluid before it enters the nozzle, making it expand more forcefully, resulting in higher specific impulse. A resistor is an electrical component which converts electrical energy into heat. Therefore, the thrust of a resistojet engine can be regulated by simply altering the wattage flowing through the resistor. Heating a fluid by 300 °C in such a way results in a 41% increase in specific impulse. If heated by 900 °C, specific impulse could be doubled in comparison to a cold gas thruster using the same propellant. See also Solar electric propulsion References External links A Xenon Resistojet Propulsion System for Microsatellites (Surrey Space Centre, University of Surrey, Guildford, Surrey) (Purchasable document) Two new ESA satellites successfully lofted into orbit (European Space Agency) Resistojet Propulsion System for Microsatellites (Alta, Italy) Rocket propulsion