How can Yutu 2 supply power? Yes, everyone can see at a glance that it has solar panel "small wings" for power supply.
Solar energy is very important, but there is a long dark night on the back of the moon. What if we can't receive solar energy at this time? It doesn't matter. Yutu II also carries a black technology, that is, the isotope thermoelectric generator based on plutonium 238, which can provide the detector with no less than 2.5W of power at the same time of heating.
Isotopic thermoelectric generator, also known as "nuclear battery" or "atomic energy battery", is a quite excellent power supply device. Its principle is simply to use the decay heat of radioisotopes to directly convert into electric energy by using Seebeck effect. Let me introduce it in detail:
The so-called Seeback effect, also called the first thermoelectric effect, refers to the thermoelectric phenomenon of the voltage difference between two substances caused by the temperature difference between two different electrical conductors or semiconductors.
Seebeck effect
Specifically, when two objects with different temperatures approach each other, there are two ways, one is molecular collision, the other is thermal radiation. The essence of temperature difference is that when two objects contact each other, there is a difference in their electromagnetic radiation intensity. Similar to the current generated by the high and low potential passing through the wire, the temperature difference can also be converted into electric energy through contact and appropriate thermoelectric elements.
The heat source of the isotope thermoelectric generator carried by Yutu 2 is a radioactive isotope plutonium 238. This material will continuously emit radiation with heat during its half-life. Through the thermoelectric converter, the heat energy continuously released by the isotope plutonium 238 can be converted into electrical energy to supply power for Yutu 2.
Isotope thermoelectric generator
For Yutu II, the isotope thermoelectric generator has a very big advantage, that is, the size and speed of the heat released by plutonium 238 are not affected by the external environment, including temperature, chemical reaction, pressure, electromagnetic field, etc. Even in the environment on the back of the moon, it can provide stable power supply, which provides great help for aerospace.
Plutonium 238
Not only Yutu II, but now almost all human space probes, such as Curiosity Mars probe, Apollo 12, 14-17 spacecraft, Pioneer, Voyager series, Galileo, Cassini, etc., use the thermoelectric generator based on plutonium 238 isotope to supply power.
Curiosity Mars Probe
It is worth mentioning that in the previous Chang'e-3, the power supply used was only the isotope heat source (RHU), which could only provide heat for the detector, but could not supply power. Maybe we had not overcome the thermoelectric conversion technology in the aviation field at that time. We still remember that Yutu 1 needs to sleep for a while after working, because it only uses solar array and lithium-ion battery pack for power supply, and can only sleep in the moonlight.
This time, Chang'e-4 and Yutu 2 are equipped with the latest isotope thermoelectric generator (RTG), which shows that our aerospace technology has made another big step.
In fact, in addition to the aerospace field, the isotope thermoelectric generator is also a magic device in the medical field. The power supply of cardiac pacemaker and artificial heart is achieved through it. Because the half-life of the selected isotope is very long, in addition to being stable, it can also supply power for a long time.
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