On May 3, 2024, Chang'e-6 was successfully launched into space by a Long March 5 Yao-8 launch vehicle at the Wenchang Cosmodrome, which will collect more soil from the far side of the moon and put a lot of things, including a mirror, yes, Chang'e-6 also has a special task - to place a mirror on the far side of the moon. It was placed for Italy, and what is more interesting is that there are already 5 mirrors on the moon, and Chang'e-6 is the sixth mirror, which is also the first on the far side of the moon, but the question is: what are so many mirrors on the moon? Even put it on the back that humans can't see, is it for Chang'e to make up?
Humans like to go to the moon and put mirrors
Since the earliest Apollo moon exploration, it has only been a few decades, and the number of times human beings have gone there is not much, but the problem is that human beings have put six mirrors on it.
The details are as follows:
1. Apollo 11: In July 1969, Apollo 11 astronauts Neil Armstrong and Buzz Aldrin deployed the first laser reflector in the Moon's still sea region. This reflector consists of 100 fused silica right-angle pyramid prisms arranged in a square array.
2. Apollo 14: In 1971, during the Apollo 14 mission, astronauts deployed a second laser reflector on the Flameolo Heights.
3. Apollo 15: In 1971, the astronauts of Apollo 15 placed a third laser reflector in the Hadley-Apennine region.
4. Soviet Luna 17 and Luna 21: The Soviet Union's unmanned lunar exploration missions Luna 17 (1970) and Luna 21 (1973) each carried a small laser reflector. The two probes are deployed with the rovers Rover 1 and Rover 2, respectively, and each rover is equipped with a laser reflector.
PS: At present, whether the United States has manned the moon has caused a huge discussion, putting a mirror does not indicate that people are gone, and unmanned vehicles can also do it, so it is difficult to say.
But from the United States to the Soviet Union, and then to today's China, they all like to put mirrors, so what is the use of these mirrors?
Fellow, can you show the way?
First of all, we have to understand that this is not an ordinary cosmetic mirror, but a high-tech laser corner reflector, to put it bluntly, it is an ultra-accurate "lunar GPS" auxiliary device. Don't look at this mirror as small, it is not small. It is made of a special material that reflects the received laser beam almost perfectly in its original way. This means that when we send a laser pulse to it, scientists will be able to capture the return signal even if the beam of light travels 380,000 kilometers between the moon and the Earth, and then calculate the precise distance between the emitting point and the lunar surface. This kind of accuracy, we're talking about the centimeter level, is much finer than if you were measuring the size of a room!
Therefore, the original function of the mirror is to allow people to accurately measure the distance between the earth and the moon, and it is also through the help of these mirrors that human beings accurately know that the moon is quietly moving away from the earth, and measure this speed: the moon is currently moving away from the earth at a distance of about 3.8 centimeters every year.
Of course, the role of these mirrors is not only used to measure the distance between the earth and the moon, but also to use them for lunar satellite navigation.
In the earth orbit, there are many satellites, and the ground base station can also maintain communication at any time, so the satellite can know very clearly its orbital altitude, location and other information, but it is different on the moon, the moon currently does not have a few satellites, and there is no ground base station to position, so the satellite can only rely on its own "eyes" to estimate the distance between itself and the moon, and the orbital position, so the error is very large, and it is not even as good as our so-called automatic driving technologyBut with these mirrors, the satellite can dock with the mirror at any time and confirm its orbital altitude, just like an accurate ground base station, isn't it very smart?
I can't see the back, so why put a mirror?
So why did Chang'e-6 go to the far side of the moon to put this sixth mirror this time? This has to start with the "face blindness" of the moon. The rotation period of the Moon, like its orbital period, means that only one side always faces the Earth, so the back side is like an unknown mystery to us. The terrain on the far side of the moon is complex and changeable, and if you want to land or explore it accurately, you can't do it without a good navigation system. And because the moon itself isn't perfectly spherical, once the mirror on the front is at height, it's not the same thing when you get to the backside.
So the mirror that Italy brought is like a light on the far side of the moon, specifically to guide the satellites that fly around the moon. Satellites can shoot lasers at the mirror and then easily calculate their position and orbit by calculating the laser round-trip time, which will provide centimeter-accurate navigation services for Chang'e-6 and other future missions. Imagine if you get lost in the forest at night and suddenly find a lighthouse in the distance, and you feel a sense of security in an instant, isn't it?
Why is Italy not made itself
Of course, some of you may ask, so why not make your own mirror? Why help Italy put mirrors? Actually, the question is very simple, if you hang a mirror on a public wall, is the mirror still yours? Can you only use it? Of course not, it's just a reflector, and it doesn't have the function of information recognition, so once this mirror is put on, it can actually be used by any country's satellite, so it doesn't really matter who made it at all.
And this incident also reminds me of the words of the great man: What is the united front? The united front is to make more of our people and less of the enemy. What wisdom!