China develops nuclear spacecraft engines

Chinese researchers are developing a 1.5 megawatt reactor that will be as tall as a 20-story building when expanded, allowing for round-trip travel between Earth and Mars.

China's experimental lithium-cooled reactor prototype. Photo: Chinese Academy of Sciences

The collaborative project between more than 10 research institutes and universities across China has made important strides towards interplanetary travel with the development of nuclear fission technology, allowing exploration of Mars on large scale. In a paper published in the Chinese Academy of Sciences journal Scientia Sinica Technologicala, the team said their prototype lithium-cooled reactor system passed some initial tests on the ground, Sun reported on March 19.

The test results confirm some of the key technological solutions that Chinese scientists and engineers have invented to shrink a megawatt-sized reactor, seven times more powerful than the system built by NASA, to an unprecedented size. ever had. When fully deployed in space, the 1.5 megawatt reactor, including its radiator, could be as tall as a 20-story building. But on the ground, the furnace will fold into a container weighing less than 8 tons.

The above design makes the reactor system easy to place and launch on a rocket, according to the research team led by scientist Wu Yican at the Academy. The reactor can also maintain stable operation in the harsh environment of space for long periods of time. According to the article, the high-power power source will make round-trip travel possible for both astronauts and cargo flights, paving the way for China's large-scale exploration of the Moon and Mars. Quoc.

Some scientists estimate a nuclear-powered spacecraft could complete a round trip between Earth and Mars in just 3 months. Currently, the scientific community agrees that this technology is essential for interplanetary missions. In contrast, spacecraft that rely on fossil fuels, such as the Starship system that the US company SpaceX is developing, may need at least 7 months to reach Mars, according to some calculations. The Starship rocket is central to NASA's plan to land astronauts on the Moon later this decade, as well as SpaceX CEO Elon Musk's ambition to colonize Mars. However, a one-way flight to the red planet would require a massive life support system.

NASA's Artemis program plans to put a nuclear reactor on the Moon and use similar technology to build a fleet of spacecraft to colonize Mars. The European Union initiated three projects to develop nuclear-related space technology. Russia also restarted a nuclear-powered spacecraft project from the Cold War era. According to Wu's research team, Russia is progressing fastest in research and development of several key technologies in the field, including nuclear fuel in space.

Researchers say China's reactor will heat up to 1,276 degrees Celsius through fission of uranium fuel, far exceeding the operating temperature of most commercial nuclear plants. The extremely high heat expands the liquid form of inert elements like helium and xenon into a gas, helping to run the generator. The chain reaction produces neutrons quickly, allowing for efficient and continuous power supply for at least 10 years. By using liquid lithium, the team was able to make the reactor smaller thanks to the element's high thermal conductivity and low weight.

Typically, heat exchangers and radiation shields take up a lot of space in reactor designs, but Wu and his colleagues say they developed technology that combines both components into one. According to the article, the reactor's heat exchanger is made from tungsten alloy, which can effectively exchange heat in the circuit while blocking harmful radiation. Other new technologies include high-temperature erosion-resistant materials. At this stage, the heat source of the reactor prototype is an external power supply. The research team's plan is to add nuclear fuel rods to make the furnace fully operational in the next steps of the test program.

The test provided preliminary demonstration of the feasibility of combining a lithium-based cooling system with the Brayton generator, which was developed in the 19th century as a piston engine and widely used in powered space flight. time. A major focus for further research and development is reactor safety during launch and operation. The mandatory requirement is that there is no risk of a nuclear explosion even if the reactor falls back to Earth. The project team also plans to apply artificial intelligence for long-term automatic operation of the reactor in space, using technology to automatically diagnose and handle problems.