Moon: Where is the nearest neighbor?

The earth and the moon, a pair of planets and satellites, are tightly tied together and dance around the same center of gravity. The biggest of the two is green, blue and white, with water and life on it. Small, only a quarter of the size of the earth, colorless, scarred and pitted, marking the passage of time. Its back is dark and bumpy, always facing the earth and the stars. What disaster happened in the distant past to make the moon so cold and desolate?

The moon is our most familiar and mysterious neighbor in space. It always arouses human curiosity and is the theme of countless ancient myths, legends and songs. The ancient calendar is based on its regular movement in the sky, and its phase change marks the change of seasons.

For scientists, there are many questions: What is the surface of the moon? How did it originate and how did it become what it is today? What are its geological conditions? What's the other side we've never seen before? Once the United States and the Soviet Union have the ability to get rid of the gravity of the earth, the moon has become the first choice for ideal exploration. Like binoculars and cameras, rockets give people new tools that can help uncover many secrets of the moon.

Between 1958 and 1976, the United States and the Soviet Union carried out 80 missions to the moon. Although only 49 tasks were completed as planned, some tasks never achieved results. But these missions-including orbiter, soft landing, photo conversation detection, two manned flights and six astronaut landings-brought back or sent back a lot of information about the nearest neighbors in space. Not long ago, the new interest in the moon inspired several new space activities. Clementine was launched in the summer of 1994, which was a joint plan of the US military and NASA. It sent back1500,000 photos and mapped 99.9% of the lunar surface. Laser technology also enabled Clementine to make detailed topographic maps of the moon, and in the process, the small spacecraft encountered reflections at the two poles of the moon, indicating that there may be ice water. This possibility is shocking. Because there is water on the moon, which provides strong support for immigration, many governments have considered immigration plans. Four years later, from 1998 to 65438+ 10, NASA launched another spacecraft, the lunar probe, whose mission was to orbit the moon and draw a map of the moon until July 1999, when scientists hoped to land near the polar region of the moon in order to send back samples of ice water that could be detected. Unfortunately, no ice was detected. Recently, the European Space Agency (ESA) launched Intelligent 1, which is a small spacecraft, and it takes 16 months to reach the moon. Its main purpose is to test solar electric drive technology. Intelligent 1 was launched in 2003 and is scheduled to reach the moon in 2004. Japan also launched a lunar probe in 2004, and China also has plans to land on the moon. After being silent for about 30 years, the moon has once again become the detection target of the solar system.

After many visits, we have learned more about the moon. About the same age as the earth: about 4.5 billion years. The relative abundance and proportion of oxygen isotopes show that the two stars were very close when they were formed, but there are different theories about the details of the formation process. Will the moon be thrown out of the earth like a drop of dye? If so, the earth must turn very fast, which has many supporters. Will it be composed or condensed by the same planetesimals (substances that make up planets) almost at the same time as the earth? If so, why not two "planets" but one? Or, could it be that the moon passed by and the earth "captured" the moon in its gravitational field? Or, in the early days of the earth's formation, when it was still in a molten state and there were many small planetesimals slowly changing inside, a huge "residual" planetesimals hit it, causing part of the earth and planetesimals to evaporate, and the molten debris sprayed on the orbit around the earth, eventually forming the moon.

Perhaps the most important legacy left by lunar exploration is more understanding of the moon, more appreciation of the earth, and key clues to solve some mysteries of the solar system. When we look at the moon at close range, what we see is only a desolate world, too small to hold the atmosphere. Unlike the earth, the moon is an underdeveloped world, only in the past, without development and change-the world is so quiet (until the next impact), and the footprints left by astronauts on its dusty surface may remain for 6.5438+0 million years. Just as fossils can tell us the history of the solar system and the earth, our trip to the moon tells us a lot about ourselves and other members of our biosphere, so we are deeply impressed by the rarity of our existence.

Of course, next, we will turn to explore the nearest neighbor planet-Venus.