During the three and a half years from 1 July 1969 to1February 1972, seven Apollo spacecraft flew to the moon, of which six were successful, and1failed, and *** 18 astronauts arrived near the moon, including 65438+. Astronauts put instruments on the surface of the moon for scientific experiments, and also collected more than 400 kilograms of lunar rocks and soil samples from the moon and brought them back to Earth for further analysis and research by scientists. According to some collected samples, the moon rocks are at least as old as the oldest rocks in the earth's crust, and the moon soil is obviously much older than rocks, approaching 4.6 billion years. Scientists hope that lunar rocks and lunar soil can provide valuable information for the origin and early history of the moon and the evolution history of the whole solar system.
Through the investigation and experiments conducted by astronauts who landed on the moon, and according to the first-hand data recorded and provided by lunar seismographs installed on the surface of the moon, we know that the moon, like planets, has layered structures such as shell, mantle and core. The outermost layer is the moon shell, about 60 ~ 65 kilometers thick; Below the lunar crust is the lunar mantle, which generally starts from the depth of 1000 km as the lunar core. The lunar mantle occupies most of the volume of the moon, and the lunar core is the highest temperature in the moon, about 1000℃.
On the moon, the direct sunlight can reach the high temperature of 127℃ during the day, and it will drop to-183℃ at night. This strange hot and cold phenomenon and the temperature difference of nearly 3 10℃ make people on earth daunting. In addition, there are active volcanic eruptions on the moon. The moon has a shell (60-65km), a mantle (1000km) and a core (the core temperature is about 1000℃). Compared with the earth, the moon should belong to a cool planet.
The field investigation and research of Apollo landing on the moon have yielded fruitful results. For example, it is found that the surface of the moon is covered with a layer of soft and porous soil, which is not thick, but is mixed with some fragments of crystalline rock; A kind of yellow soil that has never been seen before has aroused the interest and concern of scientists, but there has been no consistent conclusion on its formation. Determine that there is no obvious life on the moon at present, and it seems that there has never been life in the long history of the past; There is no magnetic field on the moon (the magnetic field intensity around the moon is less than11000 of the earth's magnetic field intensity), and there is no radiation belt around it like the earth; Of the more than 60 minerals found on the moon, at least 6 do not exist on the earth, and scientists have never heard of them. Nevertheless, many people have commented on these expensive lunar flights: although a lot of valuable information about the space environment around the moon, its gravity field, its surface topography, its appearance and internal structure has been collected, on the whole, only limited achievements have been made in scientific research on the moon, and many important and key issues, including the birth and formation of the moon and the causes of a large number of craters on the moon, have not been solved.