Lava tubes under the moon

The moon is the closest extraterrestrial body to humans. It has always been the dream of mankind to establish a manned lunar base and realize permanent human presence on the moon. In recent years, major space powers such as the United States and China have proposed manned lunar landing plans. A manned lunar base is no longer far away from us.

Recently, researchers from Chongqing University and the Beijing Institute of Space Mechanics and Electronics have cooperated to explore the feasibility of using the lunar underground lava tubes as a future manned lunar base. What factors need to be considered in building a lunar base? What are lunar lava tubes? What are the benefits of using lunar lava tubes as a lunar base? What difficulties will humans face in eventually building a lunar base? Hello everyone, I am Li Mingtao. Today, let's learn about the future construction of a lunar base.

To achieve permanent human presence on the moon, at least three key needs need to be met: First, there must be a water source. It is obviously unrealistic to transport fresh water from the earth to the moon for long-term settlement of the lunar base. For a long time, the moon was considered dry. With the deepening of lunar exploration, scientists have found evidence of water ice in the craters where the moon has accumulated. These craters have not seen sunlight all year round, and water ice may be preserved for a long time. Second, there must be energy. Unlike the 24 hours a day on Earth, it takes 28 days for the moon to rotate once. Therefore, most areas on the moon are in daytime for 14 days and in darkness for the other 14 days. So how to solve the energy problem during the long night is a very big problem. In addition to nuclear energy, there are some permanent light areas at the poles of the moon, which provide inexhaustible solar energy for the construction of the lunar base. Third, it must be safe enough. There is no atmosphere on the moon to protect it, and micrometeorites may drive straight into the lunar surface. A one-centimeter micrometeorite is enough to cause fatal damage to astronauts. In addition, the magnetic field on the moon is extremely weak and cannot shield radiation such as charged particles from the solar wind and cosmic rays, which can also cause life-threatening damage to astronauts. Therefore, shielding these radiation effects also needs to be considered. Considering the needs of water sources, energy, and security, lunar bases are often built in the polar regions of the moon, where there are both permanently illuminated areas and permanently shadowed, water-ice-rich craters, which provide convenience for the effective development of water sources and energy. In order to cope with micrometeoroid impacts and harsh particle radiation environments, artificial buildings are usually needed to shield micrometeoroids and particles. Therefore, the design drawings of the lunar bases we see on the Internet are usually built on the surface of the moon and consist of some sci-fi dome buildings.

What is the lunar lava tube? In layman's terms, it is a cenote on the moon, similar to the cenotes on our earth. On the surface, it looks like a small hole, but inside it is a different world, a huge natural cave, even large enough to accommodate a small town. How are lunar lava tubes formed? In the early days of the formation of the moon, there were a lot of volcanic eruptions. When the hot volcanic magma was flowing, its surface cooled quickly and solidified into a solid hard shell, while the temperature inside the magma was high and the flow rate was fast, thus forming a channel for the surface to solidify and the internal magma to flow. When the volcanic eruption ended, the magma was emptied to form a natural lava tube. At present, a large number of lava tubes have been discovered on the moon. The width of the largest lava tube may exceed 100 meters, and its length exceeds tens of kilometers, which is enough to fit a small town as a whole. What are the benefits of building a lunar base on the lunar lava tube? First of all, the safety is very good. The lava tube is a natural cave under the surface of the moon. It can perfectly shield the impact of micrometeorites and the invasion of solar wind. Secondly, the lava tube has good sealing and thermal insulation, which is conducive to establishing a constant temperature environment and requires low energy consumption. Although establishing a base in the lunar lava tube seems very ideal, its implementation still faces many difficulties, such as how to solve the water and energy problems of the lava tube; how to carry out construction inside the lava tube; and how to transport materials inside and outside the lava tube.

At present, human beings' understanding of lava tubes is still very limited. If we want to establish a permanent manned base in the lava tubes, we need to strengthen the research and mapping of lunar lava tubes, and understand the spatial distribution, internal structure temperature, mineral stability and other geological characteristics of lava tubes. Send a robot pilot team to carry out unmanned exploration and development experiments of lunar lava tubes, and solve the water and energy supply problems of lava tubes. Chinese scientists have planned to use the Earth's Karst Cave as a simulation site to carry out related research and experiments. It is believed that using lunar lava tubes to build a lunar base may become a reality in the near future.

This article is a work supported by Science Popularization China Starry Sky Project

Author: Li Mingtao

Reviewer: Zhou Binghong, Researcher, National Space Science Center, Chinese Academy of Sciences

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.