The lunar samples brought back by Chang'e-5
triggered a research boom at home and abroad
In December 2020, China's Chang'e-5 returner brought back nearly 2 kilograms of lunar samples, these lunar rocks have triggered a research boom among Chinese scientists, who are studying them to reveal the evolutionary history of the moon. Li Xianhua, a researcher at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, previously focused on molten rocks on Earth. But when Chang'e 5 brought China's first batch of lunar rocks back to Earth, Li Xianhua turned to studying these rocks. This time, these rock samples were collected from NASA's Apollo mission and the Soviet Union's lunar exploration more than 40 years ago. The first lunar sample brought back by humans since the mission.
Many scientists in China are currently conducting research on Chang'e-5 samples to understand the evolution of the moon. Early results have scientists excited. In the past six months, they have published six papers on Chang'e-5 samples. Last week, at the Lunar and Planetary Science Conference in Houston, Texas, USA, there was a forum on China's lunar exploration mission, and scientists submitted about a dozen research results.
(The content of the article comes from the Internet)
Cliff Neal, a professor of civil engineering and geological sciences at the University of Notre Dame, has studied Chang'e-5 samples with Chinese scientists. He said: "There are many young Chinese researchers involved, and these moon rocks are exciting because they are a window for scientists to study different periods of lunar magma activity."
The youngest moon rocks
The Chang'e-5 mission collected this batch of approximately 1,731 grams of lunar samples from the basalt area in the northeastern corner of the Procellarum in the northern part of the moon. The site was chosen in part because it may contain younger volcanic material than areas visited by Soviet lunar missions and the Apollo missions. Scientists hope that the younger sites will give them an idea of ??what the moon "looked like" as it began to cool but was still volcanically active.
The latest research results of the Chang'e-5 lunar scientific research samples released by the Chinese Academy of Sciences prove that the Chang'e-5 lunar samples are a new type of lunar basalt, filling the "gap" in the lunar sampling missions of the United States and the Soviet Union. Research shows that the moon still had magma activity until 2 billion years ago. The lunar mantle source area of ??late magma activity is not rich in radioactive heat-generating elements and is very "dry". A number of breakthrough developments have provided a new understanding of the evolution of the moon and proposed new directions for future lunar exploration and research, which have been highly praised by international experts.
In July last year, the China National Space Administration distributed the first batch of samples to a number of Chinese scientists. They selected 31 scientific projects from 85 applications and distributed about 17.5 grams of fine-grained powder and solid rock. Next, there were several rounds of applications to study lunar samples. The first research teams to date lunar rocks. On October 7 last year, a research team reported that the age of this batch of basalts was 1.96 billion years (with an error of not more than 57 million years). Less than two weeks later, another research team, including Li Xianhua, confirmed the date and estimated the age of the basalts to be 2 billion years old (with an error of less than 4 million years). These findings confirm that the Moon was still volcanically active at that time, nearly 1 billion years later than the peak of volcanic activity indicated by rocks recovered from the Apollo missions.
Confusing lunar volcanoes
What causes volcanic activity on the moon?
One theory based on satellite observations suggests that heat-generating radioactive elements found in the moon's mantle, such as potassium and thorium, may be driving volcanic activity. But when another team from IGG examined lunar basalts, they denied this. Another explanation given by scientists is that the moon's mantle contains enough water to lower the temperature at which materials melt, making it easier for magma to erupt. But IGG planetary scientist Lin Yangting and colleagues found that these moon rocks may have come from a relatively dry place.
The heat source of lunar volcanic activity also puzzles scientists. Lin Yangting said: "I haven't found the answer yet."
Xu Weibiao, a researcher at the Nanjing Purple Mountain Observatory of the Chinese Academy of Sciences, said: "This is a very big scientific problem. To figure this out, we need to further understand the evolution history of the moon." Xu Weibiao received two small pieces of lunar samples and is currently trying to figure out the problem.
(The content of the article comes from the Internet)
Currently, there are many theories about the lunar volcanic heat source. But Xu Weibiao said there will be many groups trying to solve the mystery and get more information about the moon. Since the Chang'e-5 samples arrived on Earth, he has seen many researchers join the field. This year, his lab has received more applications than they expected to join their research projects. "This has never happened before." Lin Yangting hopes more researchers will participate. Within the next decade, China plans to launch a lunar south pole sample return mission and another Mars sample return mission.
The preservation environment of lunar soil is very strict
Chang'e 5 successfully returned to Earth after completing its lunar soil collection mission, but for scientists working on ground application systems, scientific research on lunar samples can That's just the beginning. So, how will lunar samples be stored, managed and studied?
According to experts: The lunar sample laboratory mainly consists of extraterrestrial sample storage room, extraterrestrial sample preparation room, extraterrestrial sample processing and physical property analysis room and other laboratories. Samples from the moon will be stored here , unblocking and processing analysis. In the newly built lunar sample laboratory, the first room is the scientific research equipment used for safe unblocking. Since the moon is almost in a vacuum and there is a large pressure difference between it and the earth, safe unblocking has become the first problem facing the scientific research team.
The biggest problem is unsealing the equipment packaged in the lunar surface vacuum environment. In order to solve this problem, the researchers used technology and verification to finally design a plan to independently unseal the jars under vacuum conditions. After unsealing, the samples were transferred to a nitrogen environment for storage and processing. According to the scientific research team, since lunar samples are produced in a high vacuum and high reducing environment, they are easily corroded, weathered and oxidized by oxygen and water on the earth. Therefore, during the storage process in a nitrogen environment, water and oxygen indicators must also be strictly controlled. . Zhang Guangliang said: "We know that lunar soil samples are in powder form and are easily contaminated by earth materials. Therefore, to unblock its external environment, we designed it to be a clean room condition to minimize its contamination by earth particulate matter. . ”
According to the different sampling methods and sample usage, the samples collected this time will be divided into temporary storage of drill samples, temporary storage of table samples, permanent storage of drill samples and permanent storage of table samples. Four major categories, experts said: "According to the characteristics of the returned samples, there are drill sampling and surface sampling. Therefore, we classify these two types of samples and design different storage devices for storage, so that the samples can be better kept. In practice During the process, we must divide the samples according to the actual needs of scientific research, and must strictly abide by certain operating procedures to ensure that when the lunar samples are finally analyzed, the sample amount can be suitable for scientific research and will not be wasted. "For this reason. , we can see the vacuum glove box many times during the sample opening process, providing reliable and safe environmental protection for safe opening.
The function of the glove box is to fill the box with high-purity inert gas and circulate it to filter out water, oxygen, organic gases and other substances. Also known as vacuum glove box, inert gas protection box, etc. The main function is to remove O2, H2O and organic gases. Widely used in ultra-pure environments without water, oxygen, and dust. Ultimately ensuring the safe preservation of lunar soil.
After talking about moon rocks
Let’s talk about ice on the moon
For many years, scientists have believed that water ice exists in the cold craters at the poles of the moon. This is good news for scientific research and a potential resource. Now, researchers have discovered why ice persists on an extremely dry world - some polar craters may have been protected by ancient magnetic fields. Hundreds of polar craters are in permanent shadow because of the Moon's small tilt to the Sun, 1.5° compared to Earth's 23.4°.
The sun never rises from the crater's perimeter, thus keeping the temperature at -250 degrees Celsius. In some craters, the spacecraft's radar instrument detected reflective signatures from water ice, possibly caused by comet impacts.
In 2018, scientists used instruments on India's Chandrayaan-1 lunar probe to report measurements of how polar ice molecules absorb infrared light. This is one of the most conclusive evidence yet. However, explaining the presence of ice has been a challenge. Although sunlight cannot reach the crater, the solar wind can. These charged particles can destroy the ice molecule by molecule in a process called "sputtering."
(The content of the article comes from the Internet)
In this regard, planetary scientist Lon Hood of the University of Arizona and colleagues have now confirmed why the ice will always exist. At the Lunar and Planetary Science Conference in Houston recently, they presented a study showing that magnetic anomalies left over from the Moon's ancient past may be protecting these craters. Researchers have known about these anomalies since the Apollo 15 and 16 missions in 1971 and 1972, when astronauts measured areas with unusual magnetic field strengths. Some abnormal areas are currently known to be hundreds of kilometers in diameter. Although their origin is still debated, one possibility is that they were created when the moon's magnetic, iron-rich asteroids struck its surface more than 4 billion years ago. The resulting molten material may have become permanently magnetized.
Thousands of anomalies are thought to exist on the lunar surface, but Hood used data from Japan's Luna lunar probe to map the Antarctic anomalies in detail. He found at least two anomalous permanently shadowed craters - Sverdrup and Shoemaker - and there may be more. Although the remnant magnetic fields are only a few thousand times those of Earth's, they are powerful enough to deflect the solar wind.
Craters with known anomalies may become prime targets for scientific research and exploration. NASA has planned to launch a probe called "Viper" to the south pole of the moon next year. The agency intends to send humans there later this decade as part of its Artemis program. Studying the ice could reveal how it was transported, which in turn may reveal how the Earth obtained its water.
(The content of the article comes from the Internet)
It is both rock and ice
The moon so close to us
What is there hidden there? How many secrets does it hold that we don’t know?
More technology information