As we pursue the boundless frontier of exploring the universe, the choice of energy is crucial. Nuclear batteries in space provide reliable power support for space exploration with their unique working principles and long-lasting energy supply. However, regarding how nuclear batteries operate and why they can last for centuries in space, the editor and viewers are concerned about several questions: 1. What is the working principle of nuclear batteries? How do they convert nuclear energy into electrical energy? 2. Why don't nuclear batteries need recharging to last for centuries? What is special about their energy source? 3. Despite the excellent performance of nuclear batteries in space exploration, why are they difficult to promote in civilian applications? How do cost and safety issues affect their widespread use? The demand for energy in space exploration is different from that on Earth. On Earth, we can rely on various methods such as solar energy, fossil fuels, or wind energy to obtain energy. However, in space, traditional energy supply methods become impractical due to factors such as sunlight and climate limitations. Therefore, scientists began to study the use of nuclear energy as an energy source for space exploration. Nuclear batteries, as the name suggests, are devices that convert nuclear energy into electrical energy. Their working principle is different from that of traditional batteries. Traditional batteries release energy through chemical reactions, while nuclear batteries utilize nuclear reactions to generate energy. The core of nuclear batteries is radioactive isotopes, such as Plutonium-238 or Curium-242. These isotopes have stable radioactive decay characteristics and can continuously release heat energy. By placing these radioactive isotopes in nuclear batteries, heat exchangers are used to convert the heat generated by decay into electrical energy, which is then supplied to spacecraft and scientific equipment. Compared to conventional batteries, nuclear batteries have a longer lifespan. The half-life of Plutonium-238 is approximately 87.7 years, and that of Curium-242 is approximately 5.5 years, allowing nuclear batteries to provide stable electrical output for decades or even centuries. Mars rovers are typical examples of spacecraft using nuclear batteries in space exploration. Due to the short daylight hours on Mars and weather conditions such as dust storms, the efficiency of traditional solar panels on the Martian surface is greatly limited. Therefore, Mars rovers typically use nuclear batteries as their primary energy source to ensure stable operation during long-term exploration missions. Deep space probes refer to spacecraft that enter deep space areas such as outer planets of the solar system and interstellar space for scientific exploration. Since these probes leave the range of sunlight in the solar system, traditional solar panels cannot provide sufficient energy support. Therefore, deep space probes often use nuclear batteries as their main source of energy to ensure continuous operation during long-term exploration missions.