Text ｜ Ni Sijie, China Science News

Li Xianhua's name has come into the public eye time and again in connection with lunar soil research.

In 2021, he led a team that used 0.15 grams of lunar soil, 7 days to complete the analysis, 16 days to complete the paper, and 100 days to publish 3 articles simultaneously in Nature, delaying the end of lunar magmatism as perceived by the scientific community by 800 to 900 million years.

This is called the "Chinese speed" of lunar soil research.

Recently, Li Xianhua, academician of the Chinese Academy of Sciences, researcher of the Institute of Geology and Geophysics of the Chinese Academy of Sciences and professor of the University of Chinese Academy of Sciences, was listed on the list of the "Most Beautiful Science and Technology Workers" in Beijing in 2022 organized by the Propaganda Department of the Beijing Municipal Party Committee and the Municipal Science Association.

Recently, China Science News talked to Xianhua Li, who talked about his "close encounter" with lunar soil, the unknown story behind the "Chinese speed" of lunar soil research, and gave advice to young people on how to deal with the anxiety of "internal volume" and how to make high level papers.

"The moon soil is too fine." "We are in a race against history."

Science China: How did you feel when you got the lunar soil sample?

Li Xianhua: The moment I saw the lunar soil for the first time, I'm not afraid to tell you jokes, my deepest impression is that the lunar soil is too fine!

How fine are these samples? The finest fine flour we can normally buy is 100 to 120 microns, and the average particle size of moon soil is finer than fine flour, only 50 microns.

When we do research on Earth samples, we take very large rock samples for various analyses. The lunar soil we got this time was in small bottles, and the three grams of lunar soil we applied for came from two numbered samples in two small bottles, one with one gram and the other with two grams.

So we take the sample and dare not open the cap easily, because many very fine particles will not only stick to the glass wall, but also may "float" out of the bottle.

Science China: It is generally believed that scientific research fights for speed in order to gain priority in discovery. At that time, you and your team got the lunar soil and already had the advantage of the sample, so why did you still rush so much to do analysis and publish articles?

Li Xianhua: We are in a race with history.

The Apollo 11 manned lunar mission retrieved the first lunar samples in July 1969, and NASA distributed the samples to scientists in the United States and several other countries in September.

My PhD co-advisor, Prof. Tatsmoto, was responsible for the U-Pb isotope dating study of Apollo 11 moon rock samples.

The results of Apollo 11 were systematically reported in an album published in the journal Science in January 1970. So, they got the samples in September and published the article in January, almost in 4 months.

After we got the Chang'e 5 lunar soil samples back to the institute, we immediately held a kick-off meeting, and the director, Academician Wu Fuyuan, asked us to "have a clear goal, a well-defined plan, an orderly and collaborative work", and to complete the dating, rock geochemistry, water content and strontium, neodymium and hydrogen isotope analysis within one week, and then write an article for submission in another week.

At that time, the whole world was waiting for the research results of our Chang'e 5 samples, hoping to know what kind of "new lunar story" Chang'e 5 lunar soil could bring to mankind.

The fact that Chinese scientists were able to come up with research results very quickly and well after getting the samples, in itself, demonstrates the academic strength of China's lunar sample research.

Did a walkthrough with 0.1669 grams of Apollo moon dust

China Science News: Why did Academician Wu give the requirement of "one week" instead of shorter or longer?

Li Xianhua: This request is justified, and there is another story before that.

In the specimen museum of our institute, there is a sample of "Apollo moon dust", the origin of which is unknown. All we know is that it was kept in the Institute in 1971 and has been there for 50 years.

Before we got the Chang'e 5 lunar soil sample, that is, before the Spring Festival in 2021, Director Fuyuan Wu gave me the Apollo moon dust sample and asked us to answer several questions through analysis and research: is this sample a lunar soil sample or not, is it sampled back from the Apollo mission, and if it is a sample sampled back from the Apollo mission, then which Apollo mission it was sampled back from.

The analysis of this sample was equivalent to a walkthrough. The sample was very small, only 166.9 mg, and our research team, working around this 166.9 mg sample, started to work.

Having no experience in doing lunar soil analysis at that time, it took two weeks to get the results out and prove that this lunar dust sample was the sample collected by the Apollo 11 mission.

So, we actually have the technology in reserve and in mind, and we know the process and feasibility of the technology process, and we know how fast and how well we can probably do it.

The ability to produce results and publish articles in such a short period of time is also due to our team spirit and establishment working model.

Before we got the lunar soil samples, we had tuned the relevant instruments and equipment to the best condition in advance. During the research of the lunar soil samples, the teachers and students of other groups in the institute did not use these instruments and equipment, which gave the green light for the research of the lunar soil samples.

We are especially grateful to our colleagues who "made way" for the lunar soil research at that time to produce the results so quickly.

"Doing research at the expense of your health should not be promoted."

Science China: You once postponed cataract surgery so as not to delay the progress of lunar soil research, why was that?

Li Xianhua: It was really unfortunate at that time. in 1992, my right eye detached its retina, and I had an operation in early 1993. after that, the vision of my right eye was not good, so I relied on my left eye to work. after decades of using my left eye, it degenerated.

At first I thought I might be tired of work, and only in October 2020 when I had a medical checkup did I discover that it was a cataract, and at that time the Chang'e 5 moon soil sample was coming down, so if I had cataract surgery, I would have to rest and recover for a while, so I put it off, and it ended up dragging on for almost a year.

I remember that before the press conference on October 19 last year, I prepared the PPT for the press conference with several team members, who were all young people and made the PPT beautiful, but the words were too small for me to read clearly. I asked them to make the words a little bit bigger, but the words were too big and the PPT would not look good, so I couldn't see most of the words clearly during the press conference, so I could only try to keep them in my head.

Science China: Some time ago, a Chinese scientist published an article in Science magazine saying that he regretted sacrificing his health for scientific research. Do you think there is a contradiction between doing good research and keeping healthy?

Li Xianhua: Scientific research and health are not contradictory in themselves, but at certain times and under certain special conditions, there is still a price to pay.

However, we are all normal people and should lead normal lives, and doing research at the expense of our health should not be promoted.

I also hope that we do not stay up all night, the body is very important. I am now a little envious of young people, they really have a lot of energy.

How can we extend the "half-life" of the impact of our work?

China Science News: You have been selected as one of the highly cited scientists of Corevantage Global for many years, one of the highly cited scholars of ESI Global Geosciences and one of the highly cited scholars of Elsevier China, do you have any specific advice for young people to improve the impact of their research?

Li Xianhua: The ability to get a high citation rate is related to the discipline and to the content of the work.

I looked through my own highly cited articles, the first category is the new methods, new technologies, people who do research have to use the appropriate technical methods, if the technical methods are developed by you, others will of course cite when they use.

The second category is the results of work that is fundamental to the discipline. I do geochronological research, and age is the most fundamental work, and to do any thing, people will first focus on when things happened.

Another reason for being highly cited is that from the 1990s to the first decade of this century, it coincided with the rapid development of the discipline of dynamics on the mainland, and I was able to catch the "boom".

High citation is an objective reflection of solid work or not. If your work is solid, it will naturally draw attention to you.

So my advice to young people is to study the most important scientific problems in their field of expertise and to do solid work. Only solid work can prolong the "half-life" of the impact of our research results.

Science China: You mentioned that you were "just in time for the boom in the discipline", how did you get into the discipline?

Li Xianhua: I graduated from high school in 1979 with a good score on the college entrance exam. The admissions teacher from the University of Science and Technology of China came to our high school and said, "Your score is good enough to enter the University of Science and Technology. "Of course it's good to choose the Department of Earth and Space Science! In the future, you can go to space and the moon", so I "confusedly" chose this major.

Later, when I was a student in school, I read a book called "Advances in Lunar Mass Research" about the moon, which was very interesting.

When I took the graduate examination in 1983, I applied for the astrochemistry program of Mr. Ouyang Ziyuan at the Institute of Geochemistry, Chinese Academy of Sciences, but when I reported to the institute with the acceptance letter, the institute said there were too many students applying for Mr. Ouyang and transferred me to the isotope geochemistry program.

Not long ago, I talked with Mr. Ouyang about this matter, and I said to him, "Mr. Ouyang, when I took your graduate exam, you didn't accept me, but now I have to do moon soil research, you have to teach me again". After 40 years, I came back to lunar research.

"With a broader perspective, you're less anxious."

China Science News: Every generation has its own difficulties, and the difficulties that young scientists face nowadays may be the anxiety brought by the "internal volume". Have you encountered similar anxiety problems?

Li Xianhua: The "inner volume" is a problem of scientific research ecology. There seems to be a lot of anxiety among young people nowadays, why? I think the main reason for anxiety may be that there are too many challenges. Sometimes the more anxious you are, the quicker you want to achieve something.

I had a lot of challenges when I was younger. I think "challenge" is a very positive word. We often say that "opportunities and challenges coexist", if there is no challenge in life and work, it seems to be no fun, because there is no opportunity, right? If you think the challenge is too severe, you can give up a little, but if you give up when you encounter a challenge, it is "lying flat", give up the challenge, you also give up the possible opportunities. In addition, we expect something to match our own efforts.

Science China: Nowadays you and your team have done a lot of research on Earth samples and lunar soil, what are the samples you would most like to get in the future?

Li Xianhua: Because of the epidemic, I have been doing fieldwork mainly in China, and I have not been out in the field abroad for almost two years.

The last expedition before the epidemic was in September 2019, and I went to the Acasta region of Canada, a no-man's land, very close to the Arctic Circle.

Acasta is the only known place on Earth with 4 billion years of rock outcrops, where I also saw the gorgeous Aurora Borealis, a very memorable experience.

At that time I was planning to visit Greenland, where 3.8 billion years old rocks were exposed, but the trip was put on hold because of the epidemic. So, if you ask me where I'd like to go next, I'd like to go there.

For the more distant future we hope to make our due contribution to the development of earth science as Chinese geologists, so if possible, we would also like to study the samples of the back of the moon and the samples of Mars, which is what we are most looking forward to.

China Science News: How do you feel about being awarded the "Most Beautiful Science and Technology Worker" in Beijing?

Li Xianhua: I am honored, but it is not only my personal honor. I feel honored to be selected as one of Beijing's "Most Beautiful Science and Technology Workers" and to have the opportunity to introduce to you what geologists are doing.

I believe that many young people like to travel and want to see the world. If you have this idea, you should come to study geology, we can show you the mountains and landscapes around the world and explore the mysteries of them.

People who do geology will be very open-minded, because they have been to more places, they have seen more, and they will "see the strange, not the strange".