Liu Dunyi, a senior research fellow at Beijing SHRIMP Center. Photo: Chen Tao/GT

"China and the US have obvious complementary advantages regarding lunar scientific researches, and if combined together, humanity's knowledge of the moon would develop much faster…" a Chinese researcher who has studied the lunar samples from both the American Apollo missions and Chinese Chang'e missions recently told the Global Times in an exclusive interview. "It's a pity that the Wolf Amendment is like a wall standing between the two sides," he said. 

Liu Dunyi, born in 1937, is a senior research fellow at The Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences. He was the director of the center and served as the chairman of the Mass Spectrometry Society of China, as well as the vice president of the International Union of Geological Sciences. 

A leading figure in the field of isotope geochemistry in China and an international academic activist, Liu has exerted significant influence globally. In October 2014, Liu was awarded the first "Thomson Reuters Highly Cited Researchers" award. He was the only scientist from China's Ministry of Land and Resources to be selected and receive this honor.

Liu told the Global Times that throughout his career, he has studied three samples of lunar rocks. The first was in 2007, when Liu signed an agreement with the Washington University in St. Louis, which allowed him to conduct chronological research on the lunar soil samples from Apollo 12 and 14. "According to the regulations at the time, when the samples were brought to China, Americans had to be present. After the experiments were completed, the samples had to be taken away by them and could not be directly given to the Chinese side," Liu recalled.

The second portion was from China's Chang'e-5 mission. Liu said, "As soon as the samples were obtained, we immediately started the analysis. It was a race against time. I remember on the day the samples were brought, we held a meeting to celebrate, and then immediately went to the laboratory to work. The whole process was very fast, and it only took about three months." 

In the early morning of October 8, 2021, Science Online published the very first research findings on the Chang'e-5 lunar samples. The research team led by Liu and Alexander Nemchin, a senior visiting scholar at the Institute of Geology and a professor at Curtin University in Australia, proved that there was still magmatic activity on the moon 1.96 billion years ago, extending the known geological lifespan of the moon by 1 billion years and providing crucial scientific evidence for improving the lunar evolution history.

'Most anticipated results'

His third and most anticipated lunar rock study is from the far side of the moon - brought back by the epic Chang'e-6 mission. Currently, two research results of the samples are of great significance, Liu said. 

First, Chinese scientists have for the first time revealed that there was still young magmatic activity on the far side of the moon approximately 2.8 billion years ago. This age fills the gap in the record of lunar basalt samples during this period, showing that magmatic activity on the far side of the moon existed 4.2 billion years ago and lasted for at least 1.4 billion years.

In addition, a group of scientists from the Chinese Academy of Sciences discovered that the intensity of the lunar magnetic field rebounded 2.8 billion years ago. This is the first paleomagnetic field information obtained from the far side of the moon by humans, and it also provides new insights into the evolution of the lunar magnetic field. On December 20, 2024, the relevant research results were published online in the journal Nature.

"One of the most anticipated results of the Chang'e-6 samples is whether the geological structures of the samples from the near side and the far side of the moon will show any differences," Liu said. "My team's research on Chang'e-6 has also been completed. It is currently under review and will be published in due course."

Looking back at the three times he obtained the samples, Liu said with a big smile: "When I was holding the samples from the US, which was the first lunar rock, it was a very precious opportunity to study extraterrestrial objects. I was very excited. But when the Chinese brought back samples on their own, it was a whole different feeling. There was a sense of pride. We didn't have to rely on others, and it felt great."

Calls for cooperation

When it comes to international cooperation, Liu shared with the Global Times his experience of collaborating with Australian scholars, "US laws stipulate that its research institutions, universities, etc. are not allowed to cooperate with China in lunar and planetary research, but there is no such restriction on Australians. I have an old Australian friend, and his student approached me, and soon after we both wanted to work together."

Liu explained that the growing willingness of cooperating with Chinese researchers reflects the widening recognition from academicians around the world. "The Beijing SHRIMP Center we established has been open to the world since its founding," Liu said proudly. "The international community recognizes the center's strengths and abilities in geochronology research. Therefore, even facing the obstacle of US laws, they still strive to find ways to cooperate. We have done a lot of meaningful research together," he said. 

Regarding China-US space cooperation, Liu believes that the two sides have obvious complementary advantages. "The US has cultivated a group of outstanding scientists since the 1960s and accumulated a wealth of experience in lunar exploration in the 1970s. Now, China has samples of special importance, our equipment is also top-notch, and also have a team of exceptional research talents. If we could combine the experience from the US with our resources, the world's scientific research could develop even faster," he said.

He told the Global Times that a number of US fellow scientists have expressed strong eagerness to study the lunar soil with him. "Everyone knows that cooperation can spark more ideas and promote rapid progress in the entire field. However, the Wolf Amendment is like a wall standing between China-US cooperation."