"Lunar bricks" are building materials that may be used to build houses on the moon in the future, and are much harder than ordinary concrete bricks. After a while, this kind of "lunar soil brick" will fly to China's space station on the "Tianzhou-8" cargo spacecraft to conduct exposure experiments in space. What is the difference between "lunar soil bricks" and ordinary bricks? Why do they go to space?
"Lunar Soil Brick": An Uncommon "Brick"
Are the "lunar bricks" that can build houses on the moon the same as the bricks of our earth? In order to find the secret in the "lunar soil brick", the reporter came to its development site - the National Digital Construction Technology Innovation Center of Huazhong University of Science and Technology.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: The two bricks I am holding in my hand are called simulated "lunar soil bricks", and its composition is a simulated "lunar soil brick" formed by imitating the composition of real lunar soil and then sintering.
The building bricks in daily life generally have red bricks, green bricks and concrete bricks, these "lunar soil bricks" have the same density as ordinary bricks, but its compressive strength is more than three times that of ordinary red bricks and concrete bricks, which is equivalent to an area of 1 square centimeter can bear more than 10 tons of weight.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: The strength of these simulated "lunar bricks" in my hand is much higher than the red bricks and green bricks used on our earth. The two bricks we see now are mortise and tenon structures, which will facilitate the construction of such structures in the construction of future lunar bases.
Journey to Space: Validating the Three Key Properties of the "Lunar Soil Bricks".
Why did the "Lunar Soil Brick" take the "Tianzhou-8" to the Chinese space station? What kind of test does the "lunar soil brick" need to withstand in order to shoulder the heavy responsibility of building a house on the moon? Experts told reporters that there are three key properties to be verified in the space journey of the "lunar soil bricks".
If you want to build a house on the moon, you will first encounter the challenge of drastic temperature changes, with the temperature exceeding 180°C during the lunar day and -190°C on the moonlit night. In addition, because there is no atmospheric protection, a large amount of cosmic radiation and many micrometeorites will hit the surface of the moon, and there are also moonquakes with high vibration frequency, which will put forward strict requirements for the mechanical, thermal and radiation resistance of the building materials on the lunar surface.
In order to find out whether the "lunar soil bricks" can be qualified for the task of building houses on the moon, the "lunar soil bricks" will recently take the "Tianzhou-8" cargo spacecraft to China's space station. After completing space experiments, the first "lunar soil brick" is expected to return to Earth by the end of 2025.
Zhou Cheng, a professor at the National Digital Construction Technology Innovation Center and Huazhong University of Science and Technology, introduced that the three key properties of the "lunar soil brick" include:
Mechanical properties of "lunar soil bricks". Because this has the most to do with our house construction, that is, whether the mechanical properties of the sample will be degraded.
Changes in the thermal properties of "lunar soil bricks". We want to know how well it does to keep warm and insulating.
Effect of radiation on "lunar soil bricks". Because the Moon is a vacuum environment, there is a large amount of cosmic radiation, and we also want to know whether the "lunar soil bricks" can withstand the action of cosmic radiation.
How the laboratory reveals how the "lunar soil bricks" are made?
The complex environment on the surface of the moon has put forward extremely high requirements for the performance of "lunar soil bricks", and how are "lunar soil bricks" made?
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: What we are seeing now is the "lunar soil brick" formed by vacuum hot pressing and sintering. The whole process is roughly divided into three steps, the first step, we need to weigh the simulated lunar soil, and then put it into the mold according to the weight, but the lunar soil is very loose, and we need to press it in the container of the mold.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: What engineers do is to make it evenly pressurized, and then form an effective body. Once the pressure is applied, the engineer places the pressed mold with a lunar soil simulant into a vacuum autoclave and adds some insulation. After locking the entire vacuum experimental device, it can be heated and sintered.
The lunar soil materials simulated by researchers in the laboratory are scattered like the earth's soil, and they need to be fired at high temperatures, such as using an electromagnetic induction sintering furnace to heat the temperature to more than 1000 °C in about ten minutes, and the "lunar soil bricks" are fired.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: There are no other material additives in this process, so it is a 100% in-situ molding process method, which is also a very potential construction method in the construction of future lunar bases.
Space experiments have helped the research of "lunar soil bricks" to overcome difficulties
When introducing the production process of "lunar soil bricks", the researchers mentioned a word - in-situ molding process method, that is to say, in the future, we will build a lunar scientific research station, which can be made of local materials on the moon, and directly use lunar soil, solar energy, minerals and other lunar in-situ resources to build a house, without the need to transport prefabricated building components from the earth. This approach can greatly reduce the cost of building the lunar surface. These simulated "lunar soil bricks" will accumulate scientific research data for the future construction of a house on the moon after space exposure experiments, so as to optimize the actual plan.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: This is the sample that will follow the Tianzhou-8 cargo spacecraft to do exposure experiments in the space station. These are samples that simulate lunar soil sintering, divided into three sample plates, and in fact we designed the entire exposure time to be three years, so every other year we will descend a sample plate and return to Earth with the samples after the exposure on the space station, and then come back to do related experiments.
In order to make the most of the precious opportunity of the actual measurement in space, the research team designed the "lunar soil bricks" brought to the Chinese space station in two forms: columnar and sheet-shaped:
Columnar "lunar soil bricks" are mainly used for mechanical testing;
Flakes of large exposed areas are used for thermal and radiative effect testing.
In addition to the different morphologies, these "lunar soil bricks" also use 5 different simulated lunar soil compositions and 3 different sintering processes, which can provide more accurate scientific research data for the subsequent construction of the lunar base.
Zhou Cheng, professor of the National Digital Construction Technology Innovation Center and Huazhong University of Science and Technology: We have five different components, including the one that simulates the lunar sea, that is, the place where our Chang'e-5 landed (the moon), and the one that simulates lunar soil based on basalt. There are also lunar soil components that will land on the highlands for Chang'e-8, including Chang'e-7, mainly plagioclase.
Zhou Cheng, professor of Huazhong University of Science and Technology, National Digital Construction Technology Innovation Center: Like the earth, the soil in the northeast is black soil, and the soil in the northwest is loess. On the moon too, the particle composition of the soil varies from location to location and from region to region. We mainly understand its degradation laws under different molding processes, in the kind of environment of the space station. Because of the law of degradation, we can put forward a good scientific basis for material selection and process optimization.
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