Abstract: In a method and system for storing gas, especially an inert gas for elect impulse space drives which use inert gas as a reaction mass, the inert gas is filled into a storage tank in the gaseous and/or liquid state and is then cooled to solidify it into the solid state in which it is then stored. While in the earth's atmosphere, temperature regulation is achieved by means of thermal insulation of the tank and a convective heat exchange between a cryogenic coolant and the inert gas in the tank. While in the vacuum of space, temperature regulation is achieved by means of radiant heat exchange between the tank and deep space. For extracting the gas from the tank, the frozen gas is locally sublimated from the solid to the gaseous state by a controlled localized heat application, whereby the required gas pressure is developed for withdrawing gas from the tank which holds the gas in the solid state, except at a heated outlet area.