Passive reactivity control technologies that enable reactivity control of a nuclear thermal propulsion (NTP) system with little to no active mechanical movement of circumferential control drums. By minimizing or eliminating the need for mechanical movement of the circumferential control drums during an NTP burn, the reactivity control technologies simplify controlling an NTP reactor and increase the overall performance of the NTP system. The reactivity control technologies mitigate and counteract the effects of xenon, the dominant fission product contributing to reactivity transients. Examples of reactivity control technologies include, employing burnable neutron poisons, tuning hydrogen pressure, adjusting wait time between burn cycles or merging burn cycles, and enhancement of temperature feedback mechanisms. The reactivity control technologies are applicable to low-enriched uranium NTP systems, including graphite composite fueled and tungsten ceramic and metal matrix (CERMET), or any moderated NTP system, such as highly-enriched uranium graphite composite NTP systems.

A high density, generally recognized as safe, hybrid rocket motor is described, having a density-specific impulse similar to a solid rocket motor, with good performance approaching or equal to a liquid rocket motor. These high density hybrid motors resolve the packaging efficiency/effectiveness problems limiting the application of safe, low cost hybrid motor technology.

A high density, generally recognized as safe, hybrid rocket motor is described, having a density-specific impulse similar to a solid rocket motor, with good performance approaching or equal to a liquid rocket motor. These high density hybrid motors resolve the packaging efficiency/effectiveness problems limiting the application of safe, low cost hybrid motor technology.

A multi-pulse rocket propulsion motor for use with vehicles, such as space vehicles like satellites, rockets, and the like. The propulsion motor is a modular system that is capable of providing a plurality of discrete, controllable propulsion pulses. The propulsion motor can be used for primary propulsion of the vehicle and/or as a maneuvering thruster of the vehicle. The propulsion motor includes a plurality of propellant housings each containing a combustible propellant grain, a discharge plenum defining a plenum volume in communication with the discharge of each propellant housing, and a nozzle downstream from and in fluid communication with the plenum volume.

A multi-pulse rocket propulsion motor for use with vehicles, such as space vehicles like satellites, rockets, and the like. The propulsion motor is a modular system that is capable of providing a plurality of discrete, controllable propulsion pulses. The propulsion motor can be used for primary propulsion of the vehicle and/or as a maneuvering thruster of the vehicle. The propulsion motor includes a plurality of propellant housings each containing a combustible propellant grain, a discharge plenum defining a plenum volume in communication with the discharge of each propellant housing, and a nozzle downstream from and in fluid communication with the plenum volume.

A high density, generally recognized as safe, hybrid rocket motor is described, having a density-specific impulse similar to a solid rocket motor, with good performance approaching or equal to a liquid rocket motor. These high density hybrid motors resolve the packaging efficiency/effectiveness problems limiting the application of safe, low cost hybrid motor technology.

A high density, generally recognized as safe, hybrid rocket motor is described, having a density-specific impulse similar to a solid rocket motor, with good performance approaching or equal to a liquid rocket motor. These high density hybrid motors resolve the packaging efficiency/effectiveness problems limiting the application of safe, low cost hybrid motor technology.

A multi-pulse gas generator includes a pressure vessel, first and second propellants, a barrier membrane that separates the first propellant and the second propellant, an igniter device that produces combustion gas of igniter charge, and an igniter charge combustion gas exhaust device having exhaust holes configured to exhaust the combustion gas of the igniter charge against the second propellant. The barrier membrane includes: a concavely-deformable portion; and a convexly-deformable portion. A flow rate of the combustion gas of the igniter charge exhausted against a portion of the second propellant located outside of the concavely-deformable portion is larger than that of the combustion gas of the igniter charge exhausted against a portion of the second propellant located outside of the convexly-deformable portion.

A multi-pulse gas generator includes a pressure vessel, first and second propellants, a barrier membrane that separates the first propellant and the second propellant, an igniter device that produces combustion gas of igniter charge, and an igniter charge combustion gas exhaust device having exhaust holes configured to exhaust the combustion gas of the igniter charge against the second propellant. The barrier membrane includes: a concavely-deformable portion; and a convexly-deformable portion. A flow rate of the combustion gas of the igniter charge exhausted against a portion of the second propellant located outside of the concavely-deformable portion is larger than that of the combustion gas of the igniter charge exhausted against a portion of the second propellant located outside of the convexly-deformable portion.

A high density, generally recognized as safe hybrid rocket motor is described which has a density-specific impulse similar to a solid rocket motor, with good performance approaching or equal to a liquid rocket motor. These high density hybrid motors resolve the packaging efficiency/effectiveness problems limiting the application of safe, low cost hybrid motor technology.