China’s space programme will go nuclear to power future missions to the moon and Mars
- Prototype design for a powerful nuclear reactor for the space programme has been completed and some components have been built, according to researchers
- Secrecy surrounding most Chinese space nuclear reactor programmes means there is no government regulation or law on clean-up after an accident
The reactor can generate one megawatt of electric power, 100 times more powerful than a similar device Nasa plans to put on the surface of the moon by 2030.
The project was launched with funding from the central government in 2019. Although technical details and the launch date were not revealed, the engineering design of a prototype machine was completed recently and some critical components have been built, two scientists who took part in the project confirmed to the South China Morning Post this week.
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“Nuclear power is the most hopeful solution. Other nations have launched some ambitious plans. China cannot afford the cost of losing this race,” said one researcher with the Chinese Academy of Sciences who asked not to be named as they were not authorised to speak to the media.
In his last days in office, former United States president Donald Trump signed an executive order to accelerate the application of nuclear power in US civilian and military space programmes. Nasa recently opened a bid to private contractors to develop a 10-kilowatt nuclear fission device that could support a sustained human presence on the moon within a decade.
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Russia has announced a plan to launch a huge spacecraft powered by TEM, a megawatt-sized nuclear reactor, before 2030. The nuclear energy would allow the spacecraft to operate for more than a decade in the Earth’s lower orbit while carrying out additional missions to the moon or beyond.
The European Space Agency has launched a similar project, Democritos, with a 200kW space reactor to be tested on the ground by 2023.
The first nuclear power device in orbit was SNAP-10A launched by the US in 1965. The device produced 500 watts of electric power for over a month before its permanent shutdown.
One major challenge for the Chinese megawatt space reactor is cooling technology, according to a paper by a project team led by Jiang Jieqiong, a professor with the Chinese Academy of Sciences’ Institute of Nuclear Safety Technology in Hefei. The paper was published in the peer-reviewed journal China Basic Science in June.
Only some of the heat generated by the reactor would be used to produce electricity, the rest must dissipate quickly in space to avoid a meltdown. To solve this issue, the reactor would use a foldable structure like an umbrella to increase the total surface area of waste heat radiators, according to Jiang and her colleagues.
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Because of its compact size, the space reactor would operate at a temperature much higher than those on Earth (likely 2,000 degrees Celsius at the core). It would use liquid lithium as coolant for greater power generation efficiency.
But the lithium would become solid in temperatures below 180 degrees Celsius, another obstacle the Chinese team must overcome.
On the ground, a nuclear power plant receives a maintenance check every few years. Some components must be replaced because of erosion caused by the radioactive environment. Materials and hardware in a space reactor must meet a much higher standard to meet the demand of long-term space missions, according to the researchers.
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The Chinese government and military has funded numerous programmes to develop space nuclear reactors with different technical approaches, according to a study by space scientist Zhang Ze with the Shanghai Institute of Space Propulsion in the domestic Journal of Rocket Propulsion last month.
Instead of building one big reactor, some research teams were developing devices with smaller power output. These tiny modules were easier to build and could be compiled to form a bigger machine with several megawatts of electricity output, sufficient to drive up large ion thrusters to send astronauts to Mars.
The Chinese space authorities have not yet decided on their approach. The solution may be a combination of several different technologies, according to Zhang and his colleagues.
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Even though China was a latecomer to the nuclear race in space, it had several advantages, they said.
“China has a complete industrial chain to produce all the special components independently with complex manufacturing technology,” Zhang and colleagues said in the paper.
While nuclear power plant construction is shrinking worldwide, China is building new plants faster than any country – seven or eight reactors a year – with some using the world’s most advanced technologies, such as thorium fuel and high temperature gas. This infrastructure growth could give China the upper hand in terms of scientific data and talent.
But the secrecy surrounding most Chinese space nuclear reactor programmes means there is no government regulation or law on how to clean up the mess after an accident, such as a cooling failure in orbit or a launch mishap.
“It is urgently needed to establish a safety evaluation and management system that is suitable to our country’s technological status, increase the transparency in research and development progress to reduce the concerns of the general public,” Zhang said.
