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.

An interplanetary spacecraft makes use of ambient cosmic rays and muons generated therefrom to provide micro-fusion propulsion. The craft has a central reaction chamber surrounded by the craft's main body. Deuterium-containing fuel material is injected at a specified rate into the reaction chamber where it is exposed to the cosmic rays and muons to produce energetic reaction products. Some reaction products exit the chamber through an opening to provide reaction thrust, while other reaction products interact with a dome of the chamber to directly apply a thrusting force. The craft can be a preassembled station having multiple reaction chambers and can form an orbiting space station around a planet or moon or a manufacturing or habitat station on a planetary or lunar surface.

A micro-fusion powered craft has a centrally located internal chamber with an upper dome and a bottom opening. The chamber is radially surrounding by the main body of the craft. Ports from a fuel supply in the main body inject a deuterium-containing micro-fusion fuel material as a dispersed cloud within the chamber. Ambient cosmic rays and muons penetrate the upper dome into the chamber and interact with the fuel to produce energetic reaction products. The downwardly directed portion of the reaction products exist the chamber through the bottom opening to produce upward reaction thrust, while the upwardly directed portion of the reaction products are stopped by the upper dome to produce applied upward thrust. The craft may have one or more side ports for dispersing fuel material externally in a desired direction that reacts with ambient cosmic rays and muons to produce reaction products, at least some of which are received by a side of the craft to produce lateral thrust.

A craft having a source of deuterium-containing micro-fusion fuel particles is operable above a planetary, lunar or asteroid surface in the presence of ambient cosmic rays. The fuel particles are dispersible from a set of ports, where at least some of the ports are in an underside of the craft body and others are in lateral sides of the craft body. Dispersed fuel particles interact with ambient cosmic rays and muons to generate energetic reaction products, at least some which are then received by the underside of the craft to generate lift and also selected lateral sides of the craft to generate propulsive thrust in a desired lateral direction. The craft can carry tethers and winches to carry a payload above the surface from location to another. In another embodiment, a balloon-based design, such as a dirigible, provides primary buoyant lift, while the micro-fusion particles provide at least lateral thrust, and supplemental lift where needed.

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.

Establishing and growth of a lunar or planetary surface base involves continuing to use landing spacecraft as docked modules of the base for habitation and work. A first spacecraft is landed at a specified surface site then doubles as first module of the base. A second (and later third and subsequent) spacecraft is landed at the site a safe distance from the existing base modules then moved over the surface into a side-by-side position to dock with selected base modules. At least some of the landing, surface transport, and operational electric power is supplied by micro-fusion using ambient cosmic rays and muons interacting with deuterium-containing particle fuel material to generate energetic reaction products.

A collision-avoidance propulsion system and method for orbiting satellites and other spacecraft takes advantage of ambient cosmic rays in space to catalyze micro-fusion events via particle-target fusion and muon-catalyzed fusion processes, using the reaction products to produce thrust upon orbiting satellites and other spacecraft. A supply of deuterium-containing particle fuel material is propelled in a specified direction of the spacecraft in response to indication of a potential collision with another space object (e.g. orbiting debris). In one embodiment, this may be performed by propellant gas expelling the fuel material through conduits to specified ports on the exterior of the spacecraft. The propelled material interacts with the ambient cosmic rays and muon generated from those cosmic rays to induce micro-fusion. A portion of the energetic reaction products (e.g. alpha particles) are received upon the spacecraft to alter its trajectory in a manner that avoids the potential collision.

The invention is for a startup system for nuclear fusion engines in space. The combustion of hydrogen and oxygen produces heat that is used by a heat engine to produce electricity. This can be supplemented by electricity from other operating engines. The exhaust from the combustion is condensed and electrolyzed to produce hydrogen and oxygen once the engine is in operation. This provides a constant source of energy for future startups. The engine is started up at partial power in electricity generation mode and this power replaces the power from the combustion as it grows. The combustor uses the same heat engine as the nuclear engine uses for power generation.

CERMET fuel element includes a fuel meat of consolidated ceramic fuel particles (preferably refractory-metal coated HALEU fuel kernels) and an array of axially-oriented coolant flow channels. Formation and lateral positions of coolant flow channels in the fuel meat are controlled during manufacturing by spacer structures that include ceramic fuel particles. In one embodiment, a coating on a sacrificial rod (the rod being subsequently removed) forms the coolant channel and the spacer structures are affixed to the coating; in a second embodiment, a metal tube forms the coolant channel and the spacer structures are affixed to the metal tube. The spacer structures laterally position the coolant channels in spaced-apart relation and are consolidated with the ceramic fuel particles to form CERMET fuel meat of a fuel element, which are subsequently incorporated into fuel assemblies that are distributively arranged in a moderator block within a nuclear fission reactor, in particular for propulsion.

A customizable thin plate fuel form and reactor core therefor are disclosed. The thin plate fuel will comprise a fuel material embedded within a matrix material, with the entire unit having a coating. The thin plate fuel may be flat or curved and will have flow channels formed within at least the top surface of the fuel plate. The structure of the thin plate fuel will make it easier for coating with Tungsten or any other suitable material that will help contain any byproducts, prevent reactions with the working fluid, and potentially provide structural support to the thin plate fuel.