catalytic particles the medium size bedding support medium size catalytic particles the small size bedding support small catalytic particles hence the decomposition chamber is a graduated decomposition that is the catalyst bed is broken up into three beds supporting with respective sized catalyst particles the physical design of each bed incorporates wider opening gaps between catalyst bedding closer to the injector and smaller opening gaps between catalyst bedding closer to the nozzle throat the wider gaps will reduce the surface area of contact between monopropellant and catalyst which will therefore slow the rate of decomposition closer to the injector decomposing liquid closer to the nozzle throat will reduce the amount of liquid monopropellant lost due to the flow of decomposed warm gas through the decomposition chamber as decomposition proceeds and warm gas is generated pressure will rise in the decomposition chamber and gas will exit the nozzle thereby producing thrust referring to fig1 and 2 and more particularly to fig2 the flow control valve operates to provide a repeatable quantity of monopropellant each open and close cycle preferably the cycle rate is a constant rate the catalytic transient decomposition propulsion system will operate in a transient mode when the flow control valve is actuated to the open state and then back to the closed state.