What are the highlights of Change-4?

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 What are the highlights of Change-4?

Academician Ye Peijian

The neutron and radiation dose detector of Germany was loaded on the Change 4 lander. It can detect the radiation dose in the landing area, and provide the basis for the pre-assessment of the risk of future manned spacemen landing on the moon and the corresponding radiation protection. Swedish neutral atomic detector was loaded on the Change 4 lunar rover. It is of great significance to solve the key scientific problems such as the interaction mechanism between the solar wind and the lunar surface, the formation and maintenance mechanism of the lunar escape layer.

Topography camera

The lunar rover on Change 4 still has panoramic cameras, lunar radar and infrared imaging spectrometers, but Swedens neutral atom detector has been added and the particle-excited X-ray spectrometer has been removed.

The landing mode and working state of Change 4 are also quite different from that of Change 3, and its performance has been greatly improved. The front of the moon has a wider plain, although there are many craters, but even the bottom of the crater is relatively flat, so Change-3 landed slowly in an arc track. The terrain on the back of the moon is more complex, with more craters and steeper terrain. In order not to hit the cliff, a nearly vertical landing will be adopted. Change-3 cant work on moonlit night, while Change-4 can also do some measurement work on moonlit night, relying on the technology of isotope thermoelectric power generation and thermoelectric comprehensive utilization. A total of six domestic research and development scientific payloads and four international scientific payloads were deployed on Change 4 mission. They carry out scientific exploration based on low-frequency radio astronomical observation, patrol topography, mineral composition and shallow structure. The lunar landing probe also carries the Moon Micro-Ecosphere developed by Chongqing University and the large aperture laser angular mirror developed by Zhongshan University, and carries out the lunar ecosystem test and the laser ranging test beyond the Earth-Moon distance, respectively. It is reported that the Moon Micro-Ecosphere on Change-4 is a cylindrical jar made of special aluminium alloy. It is 18 centimeters high, 16 centimeters in diameter, with a net volume of about 0.8 liters and a total weight of 3 kilograms. This small pot will house potato seeds, Arabidopsis seeds, silkworm eggs, soil, water, nutrients and air, as well as micro cameras and information transmission systems. Scientists will create an environment for the growth of animals and plants in this small space and realize the ecological cycle. A small catheter directs natural light into a jar to help the plants and potato seeds grow. Potatoes and Arabidopsis were chosen as experimental species because of their short growth cycle and ease of observation by scientists. In addition, potatoes can also be used as the main food source for human survival in space.

Moon Microecosphere

Although the invisible back of the moon is vividly called the dark side, the sunshine on the back and front of the moon is almost equal. Under the external conditions of vacuum, microgravity and extreme temperature difference, the temperature and humidity of 1-30 degrees C will be maintained in the lunar micro-ecosphere, and natural light on the lunar surface will be introduced through light conduits to create a plant growth environment and explore the growth law of plants and animals on the moon. Plants in the Moon Micro-Ecosphere produce oxygen for silkworm consumption. Silkworms produce carbon dioxide and feces for plant growth. This experiment is very breakthrough and will be of great significance to the future survival of human beings on extraterrestrial planets. It will accumulate knowledge for the establishment of human bases on the moon and long-term residence. Previously, astronauts had planted plants on the International Space Station, while Chinese astronauts had cultivated rice and Arabidopsis in the Tiangong-2 Space Laboratory. But those experiments were carried out in near-Earth orbit about 400 kilometers above the ground. The environment on the moon, 380,000 kilometers from Earth, is much more complex. Lunar gravity is only 1/6 of the earths gravity, and the temperature difference between day and night is more than 200 degrees C. For this reason, the temperature in the Moon Micro-Ecosphere will be kept between 1 ~30 degree C, and the humidity, nutrients and light will be well controlled.