Domestic nuclear batteries will be loaded with the third lunar rover

China's first lunar rover, which will land on the "Chang III" moon next year, will also be loaded with nuclear power plants.

The Curiosity probe that landed on Mars this week is now looking out on the distant red land. For “non-professional aerospace enthusiasts”, to distinguish the “curiosity” from its predecessors, such as the “courage number” and “opportunity number”, is actually far more simple than imagined:

Data Map: The model of the rover that Chang'e III plans to carry.

On Curiosity, the "wings" that have long been regarded as the symbol of spacecraft - the solar cell fins - have disappeared.

The customary "wings" are set aside to fly further. "Cursic" is the first nuclear-powered rover built by humans. Moreover, as humans continue to move toward deep space, spacecraft will become more dependent on nuclear energy.

In fact, China's first lunar rover, which will land on the "Chang III" moon next year, will also be loaded with nuclear power plants. This will make our country the third country to apply nuclear power to space exploration after the United States and Russia.

Nuclear energy use can also be "miniaturized"

Ordinary people may be accustomed to linking nuclear energy with "big guys" such as nuclear power plants and nuclear submarines, but Ouyang Ziyuan, chief scientist of the Chinese Lunar Exploration Project and academician of the Chinese Academy of Sciences, told reporters that nuclear power is another kind of miniature in spacecraft. The "chemical" approach was utilized. The nuclear power plant on the Curiosity is a nuclear battery weighing about 45 kilograms and generating 140 watts of power.

The principle is not difficult to explain: The radioactive nuclear fuel in the battery is continuously degraded, releasing heat; after the thermoelectric converter works, the current eventually forms.

Unlike nuclear reactors, which rely on fission reaction power generation, nuclear batteries are based on decay reactions, and energy release is much less fissile (uncontrolled fission is a nuclear explosion).

However, the energy released by decay cannot be ignored. In the Fukushima nuclear accident in Japan, the reason why the rescue personnel quickly rebuild the damaged core cooling system is to derive the heat generated by the decay of nuclear fuel. Otherwise, the high temperature will melt the metal protective shell, leading to serious nuclear leakage.

Ouyang Ziyuan told reporters that whether the "curiosity" or the Chinese lunar rover, the fuel used in the nuclear batteries are all 238. The half life of 238 has been more than 80 years. This time is long enough for the 238 to support the battery for several decades.

Li Guoxin, a researcher at the Shanghai Institute of Space Power Sources, told reporters that when the 238 decays, the surface temperature can reach five or six hundred degrees Celsius, enough to make the ytterbium metal block appear hot red. In a nuclear battery, it is equivalent to a heat source. This nuclear battery, more standardized name is "radioisotope temperature difference battery." Its capabilities, though not enough to allow the rocket to lift off, can be used for small-scale power supplies, such as letting the Mars rover move at low speeds and talk to the earth.

Let the aircraft "immunize" against harsh environments

Li Guoxin told reporters that for deep space exploration, nuclear batteries are of great significance. In space, only spacecraft can rely on solar and nuclear power. The farther the spacecraft is from the sun, the weaker the sunlight, the lower the solar panel's power generation capacity; in order to ensure the aircraft's energy supply, nuclear power needs to be applied.

Ouyang Ziyuan stated that the "Cursic" Mars Rover has a weight of nearly 1 ton, which is about five times the "Opportunity" and "Spirit" that landed on Mars in 2004. The demand for energy is even greater. Nuclear batteries are not only immune to light, but they are also basically immune to other harsh external environments such as vacuum, cold, extreme heat, and cosmic radiation.

Ouyang Ziyuan told reporters that China’s moon rover actually uses both solar energy and nuclear energy as energy sources. The moon’s rotation is 28 days a week, which means that a “moon moon” will last for 14 days. On the lunar surface in the dark, the temperature dropped to minus 100 degrees Celsius. To prevent the onboard instruments from being frozen, the dormant lunar rover had to rely on the energy of the nuclear battery to keep warm and maintain communication with the ground. And once a new day comes, solar cells can re-drive the lunar rover. It is understood that nuclear batteries have been used in space since the middle of the last century. However, with the cooling of the US-Soviet space race, the pace of human exploration of deep space has slowed. In the near-Earth orbit, the cost-effectiveness of nuclear batteries is less than that of solar power. In addition, currently the world's 238 is mainly produced in Russia, and the limitations of fuel sources have also hampered the application of nuclear batteries.

China made great strides in independent research and development

According to Ouyang Ziyuan, the nuclear battery carried by China's lunar rover was led by China Institute of Atomic Energy.

The reporter failed to interview the relevant person in charge of the China Institute of Atomic Energy. However, a lot of information can also be obtained from the official website of the institute. Comprehensively, the website has published articles in the past few years. Since 2004, the institute has officially launched the research and development of aerospace isotope batteries; by 2006, it has developed China's first cesium-238 isotope battery; in 2008, it passed the appraisal of the expert group. . The successful development of this battery has filled a gap in our research field for a long time and marked an important step in China's nuclear power system research.

According to the official website of the Atomic Energy Agency, the indicators for the first "domestic" isotope battery exceeded the expectations and the entire development process was safe and the power was 100 milliwatts.

Although the power and the "curiosity" battery's 140 watts or so power there is still a distance, but according to Ouyang Ziyuan introduced as long as the successful development of the first battery, it can be said to break through the main technical difficulties of isotope generation. In the future, if high power is to be achieved, it is only necessary to increase the use of nuclear fuel 238 accordingly. He said that nuclear batteries may play an increasingly important role in China's future deep-sky exploration programs, such as Mars exploration.

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