Last week, the most exciting news, of course, was that China’s No. 4 successfully landed on the back of the moon, and it was the first time for humans. When the news of the successful landing on the back of the Moon on the 4th was officially announced, not only did the country applaud, but the international community also praised it, which shows how important this matter is to humans.
Excited, there will be friends who are erudite and love to delve into the question: Why is landing on the moon surface such a major impact? What is the difference between it and Apollo's successful landing on the moon?
It turns out that although there will be sunshine on the back of the moon, there is also a long "moon night". Although the night of the earth is only a short 12 hours, the night of the moon is 14 days long. It is also where the annual temperature is at -100 °C. At this time, the solar panels will lose their function, and the ordinary lithium batteries will not be able to handle such a harsh environment, and can only "silently leave the field." Precision instruments on the lunar rover will also be difficult to operate at extremely cold temperatures. In this case, the No. 4 lander and the lunar rover must find a way to get energy and supply electricity to them so that they can survive in this bitter cold.
Then, at the moonlight night, how does the No. 4 lander and its own lunar rover get energy? Now, the solar energy cannot be used here, and the ordinary battery also fails. What should I do?
There is only one way: nuclear battery.
For the image of nuclear batteries, many small partners may still stay in science fiction movies. For example, the hero of the movie "Mars Rescue" relies on the energy support of nuclear batteries and eventually escapes from Mars and returns to Earth. In reality, nuclear batteries are not science fiction, but a mature energy technology.
The principle of a nuclear battery is very simple. The radioactive ray emitted by a radionuclide is essentially an energy. Since it is energy, it can be converted into electrical energy. There are mainly the following ways to convert nuclear radiation into electrical energy: one is direct charging, and some rays are originally charged particles. For example, β-rays are actually electron currents. In this case, they can be directly used to make special devices. Charging; the second is temperature difference power generation, the radiation source will generate a lot of heat while emitting radiation (this is why after the shutdown, the nuclear fuel of the reactor core will melt, we can imagine how much energy of decay heat). Since there is heat, it is possible to use semiconductor materials for temperature difference power generation. The third is to use the photoelectric effect. This method is similar to solar power generation. First, the radiation is irradiated onto the fluorescent substance to allow the fluorescent substance to emit light. Then, the solar cell can emit light. Can be converted into electricity.
It can be said that the principle of nuclear batteries is simpler than the principle of atomic bombs. The manufacturing of nuclear batteries is much easier than atomic bombs.
At present, the most widely used nuclear battery is made of 钚-238. The 钚-238 emits alpha rays that can be converted to electrical energy by a specific conversion element.
The biggest advantage of nuclear batteries is that they are free from interference and have a long life. No matter what happens outside, as long as the nuclide in the battery still has radiation, the battery can be used all the time. Many radioactive materials have a half-life of hundreds of years, which means that many nuclear batteries can be used for hundreds of years.
Now, there is also a nuclear battery made of carbon-14. The half-life of carbon-14 is as long as 5730 years, and the theoretical life of this nuclear battery can reach more than 10,000 years.
Some people may ask, the nuclear battery has radiation, how can people live next to it? In fact, this is a misunderstanding of radioactivity. Some rays, a piece of paper can be blocked. For example, alpha ray is essentially a nucleus, beta ray, which is essentially electrons, and a piece of paper can block both rays. Therefore, a nuclear battery made of these two kinds of rays, as long as it is wrapped with a metal film, does not affect the human body at all.
The United States was the first country in the world to research nuclear batteries and invest in space exploration. In 1959, the United States developed the first nuclear battery, and in 1961 it first installed nuclear batteries on artificial satellites. Since then, the United States has launched four More than a dozen nuclear-powered space vehicles, including the famous Apollo moon landing spacecraft, the "Curious" Mars rover, and the later "New Horizons" Pluto detector. On the Apollo moon landing spacecraft, the main function of the nuclear battery is to warm the astronauts, which is equivalent to a hand warmer.
Since the 1960s, the former Soviet Union has also launched more than 20 satellites with nuclear batteries into space. Since then, Russia, which has survived the Soviet space technology cloak, is now able to produce good-performing nuclear batteries and even supply NASA to the United States.
China's nuclear battery development in the 1960s. In 1971, one year after the launch of China’s first artificial satellite, China produced the first nuclear battery. However, at that time, there were few satellites and no use, and this technology could only be temporarily saved.
After entering the 21st century, China has made rapid progress in space projects such as the Beidou positioning system and the moon landing project, and the demand for nuclear batteries has become stronger and stronger. At this time, the benefits of technical reserves have emerged.
In 2006, Chinese scientists opened the long-unpreserved nuclear battery technology and made technological improvements, and soon created a nuclear battery powered by the isotope 钚-238. In 2010, the technology was further improved. China has developed a nuclear battery with higher conversion efficiency, which fully meets the needs of the moon landing and Beidou satellite operation. In 2013, the first time, the Chang'e III landed on the moon with a domestic nuclear battery, and put down the "Yutu" lunar rover.
The research and development of nuclear batteries in China once again shows the importance of mastering core technologies. Due to the technical reserve of nuclear batteries, when we need nuclear battery technology, we can use it. For an ideal country, exploring the moon is only the first step in his space dream. His space dream should be a vast universe, and even infinite time and space. The nuclear battery, firmly in the space journey, firmly and silently do some small but significant work to serve our country's space dream.