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introduction
On the far side of the moon, there are hidden secrets that earthlings have never set foot on. In 2023, China's Chang'e-6 probe bravely marched to this uncharted land to carry out an unprecedented automatic sample return mission on the far side of the moon. But in this journey of the sea of stars, every precise landing is a challenge to the limits of technology.
When there was a heated discussion about the nearly 17-kilometer difference between Chang'e-6 and India's Chandrayaan-3, the landing deviation of up to 46 times, a heated discussion about the accuracy of space technology began. This is not only a contest of numbers, but also a manifestation of mankind's determination to explore the universe and pursue excellence.
So, how did Chang'e-6 land steadily on the rugged far side of the moon? How did China's aerospace cross the technological gap step by step and march towards the sea of stars?
A mysterious challenge on the far side of the moon
The far side of the Moon, this secret place forever facing away from the Earth, is full of endless mysteries, full of ancient impact craters and rugged highlands, as if it were an endless puzzle left by time.
Chang'e-6 has an unprecedented mission to achieve a soft landing on this untouched land, collect precious samples and bring them back to Earth. However, finding a suitable landing site is tantamount to finding a hidden door in the most complex labyrinth on Earth.
In the face of such a difficult task, scientists did not back down, but inspired more innovations. With the help of advanced remote sensing technology, they carried out a carpet reconnaissance of the terrain on the back of the moon from a distance, from huge craters to tiny rock cracks.
Through the analysis of massive data, scientists have developed a set of site selection plans specifically for the landing on the back of the moon to ensure that the landing area is both safe and meets the needs of scientific research.
Precision-guided "smart eye" - GNC system
Imagine driving a car in the vastness of the universe with no road signs, no GPS signals, and even the ground is unknown.
Chang'e-6's Guidance, Navigation and Control (GNC) system, like the eyes and brain of the brave driver, is responsible for navigating the vastness of space with precision, ensuring that the probe can land safely and accurately at its intended location on the moon.
This "wisdom eye" has a complex system of autonomous decision-making, and it needs to answer three key questions at all times: "Where am I now?" "Where am I going?" and "How do I get there?" ”
As Chang'e-6 slowly descends from lunar orbit, the GNC system begins its spectacular performance. First, it performs a "rough obstacle avoidance", which is equivalent to a quick scan of the terrain below at an altitude of several kilometers, like an experienced pilot looking down from above and picking out a relatively safe landing area.
Then, as the probe approaches the lunar surface, the GNC system activates the "Fine Obstacle Avoidance" mode, which is like a drone equipped with a high-precision camera, observing the ground up close, accurately identifying and avoiding obstacles that may hinder the landing, and finally locking on to the ideal landing spot.
This process is like driving a car into an unfamiliar parking lot on a dark night, and with only the vehicle's own radar system, it can park accurately, without any difference.
The GNC system of Chang'e-6 is such a high-tech "parking radar", but its stage is on the distant moon, and the difficulty coefficient and technological content are not the same. It is with such a "smart brain" that Chang'e-6 was able to stage a breathtaking and precise landing on the back of the moon full of dangers.
Microwave ranging and velocity sensor
If the landing of Chang'e-6 is a space dance step, then the microwave ranging and speed sensor is the precise metronome in this dance. This awkward-sounding device actually acts like the reversing sensor we rely on when parking, but it works in a much more extreme and detailed environment.
Imagine you're driving a car slowly approaching a parking space in the darkness where you can't see your fingers, when the car's radar starts working, telling you how far you are from an obstacle and how fast you can park accurately.
Chang'e-6's microwave ranging and velocimeter sensor is such a presence, except that its "car" is a priceless lunar probe, and its "parking space" is those mysterious and dangerous areas on the lunar surface.
At an altitude of only a few hundred meters from the lunar surface, this highly sensitive device kicks in, which precisely measures the lander's distance and speed to the lunar surface by emitting microwaves and receiving reflected waves.
This measurement method is not affected by the light conditions on the lunar surface, and can work stably even on moonlit nights, providing real-time and accurate data support for the lander. It's like equipping Chang'e-6 with a pair of see-through eyes, which can "see" clearly even in the lightless environment on the far side of the moon, ensuring that every step in the landing process is accurate.
With this reliable pair of "eyes", Chang'e-6 was able to make fine adjustments at the last minute to ensure that it did not "brake" too early when landing, nor did it "rush overhead" due to excessive speed, and truly achieved a "soft landing" on the surface of the moon.
The subtlety of this technology lies not only in its high precision, but also in its ability to work stably in extreme environments, which is another shining achievement of human wisdom in space exploration.
Landing legs: the secret of a "soft landing" on the moon
When Chang'e-6 traversed tens of thousands of kilometers of starry sky and finally approached the surface of the moon, the real test had just begun. At this point, four specially made landing legs became the key to its safe landing. These legs are not just supports, they are the "shock absorbers" of Chang'e-6, the last line of defense to ensure the successful conclusion of the lunar journey.
Imagine you're standing on a gravel-covered slope and trying to sit down, what would you do? Do you carefully adjust your body, find the best balance, and then sit down slowly? The landing leg of Chang'e-6 is designed with such wisdom to cope with the huge impact of the moon landing.
Each landing leg is designed to be made up of a main leg, a side leg and a soft footpad, and is lightweight yet exceptionally strong, absorbing massive impact at the moment of landing, just like the cushioning system of a premium running shoe, protecting the detector from damage. The materials and construction of the landing legs have undergone countless simulations and tests to ensure that they can still work effectively in extreme conditions, whether they encounter hard rock on the surface of the moon or soft dust.
At the moment of landing, Chang'e-6 was like putting on a pair of "moon dancing shoes" and stepped on this ancient land lightly but firmly. This is not only a precise application of the laws of physics, but also a masterpiece of human engineering. These seemingly inconspicuous landing legs carry the wisdom and dreams of astronauts, making the landing of Chang'e-6 a perfect fusion of technology and art.
Gap and prospect - the pursuit of excellence in the road to aerospace
Although there is a gap between Chang'e-6 and other international probes in terms of landing accuracy, this is not the end of the story, but the beginning of a new journey.
As the old saying goes, "the road is long, I will go up and down and seek", Chinese astronauts are not discouraged in the face of the gap, but use this as a driving force to bravely climb the peak of science and technology.
It is true that the landing deviation of Chang'e-6 is nearly 17 kilometers, which is particularly remarkable compared with India's Chandrayaan-3, but this reflects the difficulty of space exploration and the arduous challenge. Every attempt, whether successful or not, is a brave exploration of the unknown and an expansion of the boundaries of human wisdom.
The gap means that there is more room for improvement, and it means that on the journey of the sea of stars, we still have many unsolved mysteries waiting to be uncovered, and many technical difficulties waiting to be overcome.
It is a matter of pride that the success of Chang'e-6 is not only as simple as landing on the moon, but also the rendezvous and docking of lunar orbits, marking a milestone in China's aerospace technology in deep space exploration technology. This is not only a highlight moment in China's space history, but also an important page in the history of human space exploration.
epilogue
On the road of exploring the universe, there is no eternal leader, only an explorer who keeps moving forward. China's aerospace industry is marching towards a higher goal with solid steps.
Let us take Chang'e-6 as a new starting point and continue to support and pay attention to China's and the world's space industry. Behind every scientific and technological progress is the hard work and sweat of countless scientific researchers day and night.
The aerospace dream is not only the glory of the country, but also the yearning of everyone. One day in the future, when we look back at this journey, we will find that it is these gaps and challenges that have paved the way for mankind to move towards a deeper universe. The story of Chang'e-6 is a hymn to courage and wisdom, and a vivid embodiment of the human spirit of exploring the unknown and pursuing excellence.
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