In December 2020, chang 'e 5 returned to Earth with 1,731 grams of lunar soil samples. In July 2021, part of the sample was distributed in 31 copies to 13 research institutions. Soon after, the first studies of these "youngest" lunar basalts were published. On October 8, 2021, Science published an analysis of the age and composition of lunar basalts by Dunyi Liu and his team at the Beijing Ion Probe Center, Institute of Geology, Chinese Academy of Geological Sciences.
And touch the temperature of the moon
With chang 'e-5 successfully completing China's first extraterrestrial object sampling mission, China has become the third country capable of collecting lunar samples. It has been 44 years since humans touched the moon's temperature again. Half a century later, the world is curious about the difference between lunar soil and earth soil. The moon samples were surprisingly composed of volcanic rock fragments and a large amount of glass.
The United States collected 381.7 kilograms of lunar samples from six lunar sites, while the Soviet Union collected about 300 grams of lunar samples from three lunar sites. However, the moon is huge: 38 million square kilometers, or four times the land area of China. The landing site of chang 'e-5 is located in the moon's largest lunar sea "Storm Ocean", where human probes have never landed. The sampling site has a different geological background from the sampling sites of the United States and The Soviet Union, and local volcanic activities are more active, which provides a better research object for the study of the geological evolution of the moon.
The lunar soil is mainly divided into three kinds of color particles, respectively brown, yellow, white, various particles are composed of glass, olivine, feldspar and pyroxene. Among them, rock particles were ejected to the moon's surface by volcanoes, while glass particles are likely to have been accumulated and melted after the impact of the planet and dispersed into space. These lunar soil samples are fine in texture, but sharp as a knife point.
A preliminary study of storm ocean
The analysis found that the basalt samples were only 1.96 billion years old. In other words, there was magma on the moon 1.96 billion years ago. The results directly to the moon's geology lifespan of about 1 billion years, scientists had previously believed the moon in 2.9 billion years ago "death" (here refers to "death" is inside the moon is no longer active, lunar magma eruption, no longer geological stability), because the last lunar mission, "Apollo", for example, back to the life of the rock samples are more than 3 billion years. The young rocks were acquired in large part because the Chang 'e-5 mission was destined for the moon's youngest region, the Stormy Ocean.
The latest lunar age measurements by Lead author Dr. Xiaochao Che and others are exciting because they demonstrate that volcanic activity continued long after the moon's size cooled. So the question to ponder now is: what kind of heat source might have supported the moon's volcanic activity as it cooled?
The first thing that can be inferred is that the source of the energy is not concentrated radioactive decay, because the Chang 'e-5 samples do not contain large amounts of the chemical elements associated with such an effect.
"One possible scenario we discuss in our paper is that the moon may be able to stay active for a longer period of time due to orbital interactions with the Earth," speculated Co-author Dr Catherine Joy of the University of Manchester in the UK. It could be that the moon swings back and forth in its orbit, causing what we call tidal heating. So, it's kind of like the moon generates ocean tides on Earth, and maybe the gravitational effects of earth could stretch and bend the moon to create frictional melting."
It depends on the year
In addition to proving that the moon is geologically active later than expected, the new study has another major significance: it helps scientists calibrate crater-counting techniques used to date the planet's surface.
Scientists believe that the more craters they see on the surface, the older the area must be; Conversely, the fewer impact craters there are, the more recently the region has formed. But such dating techniques must be based on some absolute date from a sample, which is difficult for the moon. Given this, the chang 'e-5 samples are important for providing precise coordinates for a range of 100 million to 3 billion years.
Professor Brad Jolliffe, from the University of Washington in the US, is another author of the paper. He wants China to target its next sample collection mission to the South Pole on the far side of the moon, the Aitokan Basin (the moon's largest impact crater) - a giant crater some 2,500km across and 8km deep that was created by a giant impact early in the moon's history. If chang 'e-6 goes to the South Pole, aitokan Basin, it will bring back the age of the moon's oldest large impact craters - perhaps 4 to 4.5 billion years. Currently, we don't know how much the superimpactor melted, and samples from the South Pole-Aitokan basin could answer that question.
High utilization value
Compared with the lunar soil samples sent to China by the United States, the difference is that there is no glass in the American samples, which is also caused by the different sample types.
When it comes to the lunar soil, ordinary Chinese will think, is it possible to grow vegetables on the moon? The lunar soil is mainly composed of oxygen, silicon, iron and other elements, but lacks organic matter, water and other important components for plants to survive. In addition, the extreme environmental conditions of light and temperature on the moon, combined with the vacuum and high radiation, make it impossible for plants to survive with current technology.
However, scientists say it is possible to create an environment suitable for plant growth by modifying the lunar soil and adding the necessary nutrients.
But with the moon soil to grow vegetables, really overqualified to use a bit, in fact, it contains rich energy. The long-term solar wind in space has carried huge amounts of helium-3 as a clean energy source in the lunar soil, totaling 1 million to 5 million tons, far exceeding the reserves on Earth. For example, 100 tons of helium-3 could carry as much energy as the world currently consumes in a year.
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