A multi-pulse rocket is equipped with a thermally insulating barrier that serves as a rupture disk or a movable plug or plate separating staged propellant grains. When a rupture disk it used, the disk can be equipped with a pyrotechnic actuator to weaken the disk upon command, enabling the propellant grain on the fore side of the disk to burst the disk at a relatively low pressure when ignition of the propeiiant grain is needed for additional thrust. Rupturing of the disk can also be controlled by attitude maneuvering ports on the tore side of the barrier whose open or closed conditions are controlled by independently operable closures. When a movable plug is used, the plug is movable between a closed position separating rocket chamber into subchambers isolating the propellant grains from each other and an open position allowing the flow of combustion gas between the two subchambers.
