He trained a pair of "smart eagle eyes" in Hangzhou for the "moon run"

Image source: Hangzhou Release

"Dad, when can you go to the moon?" Dandan, a first-grade student, admires her father Xu Xuesen. For her, the moon in the sky is not only related to Yutu and Chang'e, but her father is also a person who is very close to the moon. "The child doesn't understand a lot of profound scientific knowledge, but she knows that my work is related to the moon." On the eve of the Mid-Autumn Festival, the reporter came to Xu Xuesen's workplace, the School of Physics and Optoelectronic Engineering of the University of Science and Technology of China Hangzhou Institute for Advanced Studies. In the laboratory separated by a door in the corridor on the first floor, two "visitors from the moon" were quietly "lying". Two months ago, Xu Xuesen and Shu Rong, chief professor of the Hangzhou Institute for Advanced Studies, went to Beijing together and brought two Chang'e 5 lunar samples to Hangzhou. This was the first time that Zhejiang Province obtained lunar samples with the official approval of the National Space Administration.

Xu Xuesen and Shu Rong, chief professor of Hangzhou Higher People's Court, show the lunar sample certificate. Photo provided by the interviewee

Xu Xuesen is not an astronaut, but the "spectral payload" he participated in developing has flown into space and landed on the moon many times. Focusing on lunar soil research, they want to design and test more advanced instruments to provide the most direct technical support for my country's subsequent lunar exploration projects.

Two Chang'e 5 lunar samples provided by the interviewees

"8 am to 10 pm"

They want to build a pair of lunar soil "eagle eyes"

Xu Xuesen just spent a very busy summer vacation. "I often forget what day it is today." With two dark circles under his eyes, he pointed to a green device next to him and told reporters that at the end of August, we were doing the calibration work for the scientific payload of Tianwen-2.

The large green device is cylindrical and looks like a lying rocket. Xu Xuesen introduced that this is a planetary surface environment simulation platform, which can be evacuated into a vacuum, and can also be set to extremely low or high temperatures to simulate the planetary surface environment. During the most intensive days of the experimental cycle, team members need to conduct different experimental tests every day. Fix the scientific payload in the equipment to test the stability and reliability of the instrument operation under different conditions. "From determining the experimental plan to completing the experiment, it basically takes 8 am to 10 pm every day." Xu Xuesen said.

"From Chang'e 2 to Chang'e 6, my country's lunar exploration probes have been equipped with scientific payloads developed with the participation of Professor Shu Rong's team, and I am also a member of the team." Xu Xuesen told reporters that spectrometers play a vital role in recording, analyzing, and testing lunar soil.

There are many material resources hidden in the lunar soil that humans have not yet discovered. When sunlight shines on the surface of different materials, it will present its unique spectral characteristics, "just like human fingerprints, it is unique." When the spectrometer has this data, it can determine and identify the different components contained in the lunar soil.

Previously, scientists have successfully verified major achievements, such as the sixth new mineral "Chang'e Stone" discovered by humans on the moon; and the naturally formed few-layer graphene discovered by Chinese scientists in the lunar soil for the first time, all of which were achieved with the help of different analysis techniques.

If you want to do your work well, you must first sharpen your tools. Now, Xu Xuesen's team is going to make the two lunar soil "Eagle Eyes" more refined. Imagine that when the Chang'e probe arrives on the moon, a spectrometer payload that can measure a wider wavelength range and has a higher resolution can help the probe to distinguish the composition of the lunar soil materials it detects faster and more accurately, and the subsequent "digging" mission process will also be smoother and more effective.

On September 3, the official news of China's lunar exploration project was released, and the prototype development work of the Chang'e-7 mission is underway. "An important task of Chang'e-7 is to conduct a geological survey of the lunar south pole," Xu Xuesen revealed. "By conducting spectral calibration and experiments on real lunar soil, the team will further transform and upgrade the software and algorithms of the spectral instrument. More accurate lunar soil data will also improve the recognition effect of the spectrometer, helping scientists to discover more secrets of the moon using Chang'e-7 scientific data."

Be extra careful

Protect the baby from the moon

In 2020, Chang'e 5 landed near the Rumker Mons in the northern Ocean of Storms on the Moon and returned to Earth with 1,731 grams of lunar soil. This less than two kilograms of extraterrestrial soil has a particularly great historical significance. They are the first new lunar samples brought back from the moon by humans in nearly half a century, and it is also the first extraterrestrial sampling mission completed by my country.

At present, two samples from the 1,731 grams of lunar soil are "temporarily residing" at the University of Science and Technology of China Hangzhou High School. One is a 200 mg powder sample, and the other is a 13 mg optical sample. The total weight of the two samples is 213 mg. When the one-year research cycle is over, the team needs to return the two samples and ensure that the loss rate does not exceed 10%.

The lunar soil "glove box" seen from the surveillance camera. Photo by reporter Lin Chenchen

It is easy to imagine how much Xu Xuesen and other scientific researchers treasure this handful of soil. Xu Xuesen has a monitoring app installed on his phone, which allows him to see the current situation of the lunar soil. Xu Xuesen said that he would open it once or twice a day to take a look. "The lunar soil laboratory requires a strict approval process to enter. Although I know there will be no problems, I just want to take a look to make sure the lunar soil is still intact."

During the first week after bringing the lunar soil back to Hangzhou, Xu Xuesen suffered from insomnia almost every night. He thought about how to protect this precious "local specialty" 380,000 kilometers away from Earth, together with the moon hanging in the sky every night.

First, we need to create a sufficiently strict and "perfect" environment for preserving lunar soil. At present, the "glove box" for storing lunar soil strictly controls the gas environment: the water and oxygen content is less than 0.1ppm (parts per million) and is filled with inactive nitrogen. Two cameras "monitor" them all year round, and the monitoring equipment next to them displays environmental humidity, temperature and other data in real time. The Hangzhou High Court is also building an 80-square-meter exclusive laboratory for lunar soil - a Class 10,000 clean room to make full preparations for future lunar soil experiments.

When the lunar soil just arrived in Hangzhou, Xu Xuesen put the lunar samples into the "glove box". Photo by reporter Ni Yanqiang

"At present, we have not opened the lid of the lunar soil," said Xu Xuesen. "Based on a loss rate of 10%, the loss of 200 mg of lunar soil powder sample cannot exceed 20 mg. Maybe when the lid is opened once, a gust of air can blow away the soil." The team is determined to use this "priceless soil" only when the instrument technology is fully mature. They must be extremely careful in operation and make good use of the limited number of tests to obtain as much data as possible.

A strange name coincidence

Inherited scientific research sentiment

Earlier this month, Nature published the latest results of the Chinese scientific research team's study of the lunar soil of Chang'e 5: 120 million years ago, there was still volcanic activity on the moon. In other words, if we travel back to the time when dinosaurs lived, when we look up at the moon, we may observe the spectacular phenomenon of volcanic eruptions on the moon.

The property of the moon that "people today cannot see the moon of the past, but the moon today once shone on the ancients" was a major motivation that initially attracted Xu Xuesen to choose lunar soil spectroscopy research. He did not pursue planets that were out of reach and billions of light years away. He felt that there was still a lot of unknown research potential in the visible ones. The closest planet to the earth is the moon, which is a scientific research field worth devoting a lifetime to.

"My daughter now has a dream of becoming a scientist," Xu Xuesen said with a proud smile, "Maybe my job is more mysterious and fun to her." In his daily education, he would not deliberately mention the hardships of scientific research, nor would he particularly exaggerate the "weight" of this job, but he would strive to answer all questions. When his daughter was in kindergarten, he also went to the class to teach a popular science class on lunar knowledge.

Xu Xuesen has been serving as a master's tutor at the University of Science and Technology of China Hangzhou High School since last year. In his opinion, the inheritance of the spirit of scientists is essential for generations of young people. He said: "My name and my idol Qian Xuesen have two characters in common, but my parents didn't deliberately choose them. But it was just such a coincidence that subtly planted the sentiment of 'serving the country through scientific research' in my heart. We can't compare with the selfless and noble spirit of our predecessors, but we only hope to follow their example and emulate their excellent qualities in our work."

Xu Xuesen and his team put the lunar soil samples into the transition cabin of the glove box. Photo by reporter Ni Yanqiang

Therefore, this Mid-Autumn Festival is likely to be just an ordinary day for him - he will not go back to his hometown to enjoy the moon, but will stay in the laboratory to further improve the spectral analysis instrument for the "visitors from the moon". A year of lunar soil research is fleeting, and the team must race against time to complete each stage of the task.

The "Chang'e Project" is named after the classical and romantic Chinese myth "Chang'e Flying to the Moon". Behind the scientific version of "Chasing the Moon" day and night, there are many unknown scientific researchers like Xu Xuesen who continue to strive to truly realize the ideal of flying to the moon. It is also because of their strength that we are constantly getting closer to this full moon and constantly fulfilling the ideal of "flying to the moon" from ancient times to the present.