At 14:07 on June 25, the Chang'e-6 returner landed in the predetermined area of Siziwangqi in Inner Mongolia, with a landing point prediction accuracy of more than ten meters.
Hu Hao, Chief Designer of the Chang'e-6 Mission: What I am looking forward to the most is that the lunar samples will really produce new results. Because this is the first time we have obtained samples from the far side of the moon, this matter is very important in the international community, and everyone has some expectations. Whether the far side of the moon is as different from the front side as we imagined, where it is different, and what new insights it will bring, this is something I am very much looking forward to.
On June 26, Chang'e-6 completed the opening of the cabin for sampling. On June 28, the China National Space Administration held a handover ceremony for the lunar samples of the Chang'e-6 mission, and after measurement, the Chang'e-6 mission collected a total of 1,935.3 grams of lunar samples. After the samples are safely transported to the lunar sample laboratory, the scientists will start the scientific research work by storing and processing the lunar samples as planned. From the launch of the Chang'e-6 probe on May 3 to the successful landing of the Chang'e-6 returner on June 25, the 53-day lunar exploration journey was the hard work of Hu Hao and tens of thousands of astronauts day and night.
In 2004, China officially launched the lunar exploration project, which is divided into three stages: "unmanned lunar exploration", "manned lunar landing" and "establishment of a lunar base". At present, the lunar exploration project is implementing the mission of "unmanned lunar exploration", according to the three-step strategy of "orbiting", "falling" and "returning", Chang'e-1 and 2 have achieved lunar orbit, Chang'e-3 and 4 have achieved lunar landing, and Chang'e-5 has landed on the front side of the moon and returned with samples, and as a backup for Chang'e-5, Chang'e-6 has been given a new mission to land on the far side of the moon and sample back, which is an unprecedented challenge.
On March 20, 2024, the Queqiao-2 relay satellite was launched and successfully entered the orbit around the moon, providing communication support for the next Chang'e-6 mission.
Hu Hao, Chief Designer of the Chang'e-6 Mission: There are many kinds of plans. We even have a plan for what you will do if something goes wrong with the relay star. For example, what if there is no relay after we fall, and we lose contact with the ground? If the probe itself is still good, it will carry out a series of autonomous activities, and give itself programmed instructions, including drilling, lifting, and taking off at the right time, and these capabilities will have to be judged and executed independently.
On June 2, after nearly 30 days of journey to the moon, the Chang'e-6 probe arrived over the pre-selected landing area of the South Pole-Aitken Basin on the far side of the moon and prepared to land.
Hu Hao, chief designer of the Chang'e-6 mission: I am worried about whether we can reliably land in a better place, this matter has always been the biggest thing, because it not only involves landing, but also involves whether our sampling is smooth and whether the ascent conditions are very good.
Because there are no real-time images, researchers can only use telemetry data to determine the state of Chang'e-6 when it lands on the moon.
The terrain of the Antarctica-Aitken Basin is extremely complex, and there are large and small highlands near the landing area, and scientists have equipped the Chang'e-6 probe with microwave sensors, laser sensors and a series of optical imaging sensors to enhance its automatic identification and obstacle avoidance functions.
Hu Hao, chief designer of the Chang'e-6 mission: I can avoid obstacles, my probe will not fall into the pit by itself, but will find a relatively flat place to land.
Hu Hao, chief designer of the Chang'e-6 mission: Because of the influence of lunar dust, the engine was turned off before the moon landed, and the probe fell to the moon in free fall, about 4 meters high, and we fell down ourselves.
After a smooth landing, Chang'e-6 began its sampling mission. Prior to this, humans had taken 10 samples on the moon, but all of them were on the front side of the moon, so this sampling on the far side of the moon has attracted the attention of the world.
Reporter: One is surface mining, the other is drilling, why do you take two ways?
Hu Hao, chief designer of the Chang'e-6 mission: Drilling samples and surface extraction are mutual backups, that is, both methods have heterogeneous backups to ensure that we can get back the samples.
In particular, the unknown geological conditions on the far side of the moon have brought great challenges to the drilling work of Chang'e-6.
Hu Hao, chief designer of the Chang'e-6 mission: I can't judge what the state of the moon is underground, and if I hit the rocks, I will be more difficult.
Reporter: Can you move again?
Hu Hao, chief designer of the Chang'e-6 mission: I can't move the position, if the cost of moving the position is very large, I have to add a lot of functions to move the position, so I might as well shovel it, so it may be more effective.
Hu Hao, chief designer of the Chang'e-6 mission: We drilled a little more than 1 meter this time, but we still failed to meet expectations, and the underground situation is indeed complicated.
In Hu Hao's view, the failure to achieve the expected drilling depth has become a fly in the ointment of the Chang'e-6 mission.
Hu Hao, chief designer of the Chang'e-6 mission: Because we need a lot of power when drilling, we don't do anything else and keep drilling, so I don't know in advance whether we can continue to drill deep. There is a trade-off between the time to work on the moon and the energy of the probe. Therefore, after the unanimous judgment of our experts, we feel that there may be a stone stuck there, and if we drill down, we may lose some of the results of the previous drilling.
After 48 hours, Chang'e-6 successfully completed sampling on the far side of the moon and stored the samples in the storage device carried by the ascender in the predetermined form.
Hu Hao, Chief Designer of the Chang'e-6 Mission: We still have to grab the jar and hang it into the big jar, and the whole series of operations is actually very complicated, very precise, and difficult. We did a lot of experiments on the ground, and we did a simulation platform to drill on the ground.
Hu Hao, chief designer of the Chang'e-6 mission: For this action, it requires a high level of precision, millimeter-level, and it is indeed very difficult to operate the moon on the ground to achieve millimeter-level accuracy. And it also depends on the attitude of the probe that we have landed on the moon, whether it is crooked or positive, which is not the same.
Reporter: If it is crooked, it can be so successful.
Hu Hao, chief designer of the Chang'e-6 mission: We can also complete this mission, we have done such experiments, how dare we go to the moon without such a preparatory plan?
After the sampling work was completed, the five-star red flag carried by the Chang'e-6 lander was successfully launched. In addition, a pattern similar to the character "Zhong" was left at the sampling location, which triggered many people's interpretation of "Chinese-style romance".
Hu Hao, Chief Designer of the Chang'e-6 Mission: Many people said on the Internet at the time that you consciously came up with a Chinese character. In fact, we really don't consciously do this, this is not only like a Chinese character, some people think it is like a dove of peace, and some people think it is like a person coming from the moon. That's why I say it's a matter of opinion, not deliberate.
Also impressive is the full-length photo of Chang'e-6 on the far side of the moon, which comes from a photorobot who landed on the moon with Chang'e-6.
Hu Hao, chief designer of the Chang'e-6 mission: This little robot has two sides, and the other side has solar energy. There are cameras on both sides, and it's the same for turning them over. The ground can tell it instructions through wifi, but if it is not needed, it can be completely autonomous, and it is a very independent "child".
On June 4, the Chang'e-6 ascender carrying lunar samples took off from the far side of the moon and then successfully entered the predetermined orbit around the moon and embarked on its journey home. On June 6, the Chang'e-6 ascent vehicle successfully completed the rendezvous and docking with the orbiter and the returner assembly, and safely transferred the container containing lunar samples to the returner.
On June 20, the orbiter and returner combination ignited and entered the Earth-Moon transfer orbit. On June 25, about 5,000 kilometers from Earth, the returner and orbiter separated and began to rush to Earth at a speed of nearly 11.2 kilometers per second.
Hu Hao, chief designer of the Chang'e-6 mission: These are all ablative, because it is a windward side, we have a short distance this time, Chang'e-5 ran 6,500 kilometers, this is only 5,600 kilometers, the distance is short, and the ablation speed is still so fast, so the ablation is more severe than Chang'e-5.
Reporter: The temperature in this cabin must be kept fixed.
Hu Hao, Chief Designer of the Chang'e-6 Mission: Yes, and we also have some seeds in it, and the seeds will go bad if they are too hot.
The Chang'e-6 mission has achieved major breakthroughs in a number of key technologies, and at the same time, it has carried out pragmatic and efficient international cooperation with four international payloads, making contributions to the world's lunar exploration cause.
Hu Hao, Chief Designer of the Chang'e-6 mission: The experts from ESA told me that they were 300% satisfied with the fact that they were in charge of the negative ion detector and that they had indeed found something that they thought were valuable through this collaboration, and that they were writing papers. So I think this cooperation is very meaningful here, and I think the effect is good to be able to cooperate with each other and obtain a new scientific research result in more than a year.
Zhang Kejian, Director of the China National Space Administration: Chang'e-6 came back on June 25, which is also the 100th anniversary of the birth of my old dean, Comrade Deng Jiaxian, and I think this is the best gift. It should be said that the inheritance of our spirit of "two bombs and one satellite" is actually passed down from generation to generation.
The successful completion of the Chang'e-6 mission announced that the mainland lunar exploration project had entered a new stage. According to the plan, Chang'e-7 will be launched around 2026 to carry out environmental and resource exploration at the south pole of the moon. By around 2028, Chang'e-8 will be launched, and the technical verification of the in-situ utilization of lunar resources will be carried out, and the landing of Chinese on the moon will be realized by 2030.
Hu Hao, chief designer of the Chang'e-6 mission: There will definitely be supporting work, because our probe has already reached the moon, and has worked from the moon, and returned smoothly from the moon to get back the things on the moon. We have already built this bridge, because it is a dream for the Chinese to stand on the moon.
Hu Hao, chief designer of the Chang'e-6 mission: At that time, the national flag was planted, and the national flag must be planted there, I think this will be realized soon, and now we are running to the moon at full speed.