At 12:41 on the 23rd, the "Tianwen-1" probe, which undertook China`s first Mars exploration mission, was successfully launched at the Wenchang Space Launch Site in Hainan. This is not only China`s first fully autonomous Mars exploration mission, but also China`s deep space field. A brand new milestone in it. So, behind the successful launch of the "Tianwen-1" detector, what high-performance materials played an important role?
The cloak of escort: heat-resistant composite material
The Institute of Aerospace Materials and Technology has developed three types of heat-resistant composite materials based on the shape of the detector, the aerodynamic load on different parts and the heat flux density. They used ultra-light honeycomb reinforced low-density ablation and heat-proof materials for the Mars probe on the outsole structure and the corners of the outsole that are the most aerodynamically heated; used at the upper and lower edges and structural support parts that need to maintain the overall shape of the probe Continuous fiber-reinforced medium-density heat-resistant material is used; heat-resistant coating material is used for the back cover part where the aerodynamic heating is relatively gentle.
Honeycomb reinforced low-density ablation and heat-proof materials are commonly used materials for space detectors. The new ultra-lightweight honeycomb reinforced low-density ablation heat-proof material is used on the Mars rover. This material has higher strength and lower density. It can be optimized according to the aerodynamic load distribution, and it can be lighter while ensuring that the detector can withstand more severe aerodynamic loads. The integrated molding technology makes the entire probe outsole structure have a very good integrity, ensuring its structural stability to withstand high and low temperature alternations during the process of running to Mars.
The mass of the "Tianwen No. 1" detector cannot be too large, which means that the quality of the heat-resistant structure and materials needs to be compressed as much as possible. Here is where continuous fiber reinforced medium-density heat-resistant materials come in. The material is mainly used as the hatch cover, edge sealing ring, embedded parts, screw plug and other parts of the heat-proof structure of the detector outsole and back cover. It has higher strength than low-density materials, and takes into account ablation resistance and bearing capacity. The material uses the SPQ fiber cloth reinforcement system composed of ternary long fibers, and introduces lightweight fillers into the continuous fiber reinforced prepreg to realize the lightweight of the continuous fiber reinforced ablation and heat protection material.
Unlike the probe's outsole facing the Martian atmosphere directly, the back cover structure is on the side of the lander, and the heat flow is relatively lower. The ultra-low-density heat-resistant coating material developed by the Institute of Aerospace Materials and Technology has basic thermophysical properties reaching the international advanced level. This material not only has excellent thermal insulation properties, but also plays an important role in the weight reduction of the lander.
The structural thermal matching between the above materials should also be considered. The three kinds of heat-proof materials need to maintain good structural thermal matching and integrity with the internal structure of the detector. Through engineering calculations, numerical simulations and necessary ground tests, the researchers analyzed the structural changes of these three materials in extremely low temperature and high and low temperature alternating space environments, and then optimized and corrected them based on the experimental results to ensure the matching of the three materials And integrity, so that they can "cooperate" in the boundless space, and escort the detectors to arrive safely and land smoothly.
The production of thermal insulation materials has been strongly supported by materials technology companies. In the process of cooperating with the development of China`s first Mars rover, HNLY Advanced Materials Technology Group has strengthened research and development, strengthened production process control, and increased the frequency of quality control testing to ensure product quality in accordance with specific indicators such as lighter materials and more stable performance required by the project. Strictly control at 6~7 kg/m3, which reduces the weight by 30% compared with conventional products. The material's sound absorption, heat insulation, porosity and other indicators are all superior to the specified standards. The reliability of performance and the professionalism of application support have been recognized by the partner China Southern Airlines Super Insulation Material Laboratory and aerospace equipment contractors. Provide guarantee for the partner to further modify the product, reduce the thermal expansion coefficient of the material, and improve the dimensional stability in a wide temperature range.
Helper to ride the wind and waves: energy power system
To fly to Mars, having the power to break through the speed of the second universe is the prerequisite for breaking away from the gravity of the earth. The "Tianwen-1" probe carried this time is the Long March 5 Yao-4 launch vehicle, which has powerful power and amazing speed. This time, the Sixth Academy of Aerospace Science and Technology Group developed and produced 4 types of 30 sets of engines for the Long March 5 Yaosi carrier rocket, including 8 120-ton liquid oxygen kerosene engines, 2 50-ton hydrogen-oxygen engines, and 2 9-ton engines. Stage expansion cycle engine and 18 attitude control engines as auxiliary power.
As China's first Mars exploration mission, the "Tianwen-1" probe will achieve the three goals of "surround, land, and patrol" Mars through a launch mission. To undertake the important task of patrol and exploration of Mars and complete the 90-day patrol and exploration mission, the "Tianwen-1" probe needs to carry a variety of sophisticated detection instruments, and the most important thing is energy supply, which is related to the survival of the Mars rover. .
To this end, the "Tianwen No. 1" detector is equipped with a "expandable flexible solar cell system based on a shape memory polymer smart composite structure." The system mainly includes the shape memory composite material lock release mechanism developed by HEB, the shape memory polymer composite material expandable beam and the flexible solar thin film battery developed by the Shanghai Space Power Research Institute. The system is based on composite material mechanics theory, fine structure design and shape memory polymer composite structure, which can realize the functions of locking, releasing and unfolding flexible solar cells, as well as high rigidity and bearing capacity after unfolding.
Randomly strained protective layer: organic thermal control coating
After the "Tianwen-1" probe enters orbit, it is in an ultra-high vacuum space environment outside the earth's atmosphere. The surface facing the sun is very hot, and the surface facing away from the sun is very cold, resulting in a huge temperature difference on the spacecraft. Therefore, in order to ensure that the "Tianwen-1" probe can maintain normal operation in extreme environments, China has adopted a variety of super cutting-edge new manufacturing technologies and high-tech materials to better adapt to the complex environment of space.
If the surface temperature of the spacecraft exceeds the appropriate range of use, the instruments and equipment carried by the spacecraft are easily damaged or stop working directly. Therefore, in order to ensure that the surface temperature of the instruments and equipment is in a normal working state, the spacecraft needs to be thermally controlled. In other words, a protective layer that can adapt to changes is needed to protect the normal operation of the spacecraft.
Under normal circumstances, researchers adjust the thermal equilibrium temperature of the spacecraft by using coatings with different solar absorptivity and thermal emissivity on the outer surface of the spacecraft to ensure that it works within the appropriate operating temperature. The organic thermal control coating developed and produced by the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences is a material that achieves thermal control requirements by regulating the temperature on the surface of spacecraft and instruments.
This kind of coating has emerged since the birth of my country's first artificial satellite "Dongfanghong-1". Through decades of development, dozens of organic thermal control coatings for different purposes have been developed. The Chang'e series satellites have also used the organic thermal control coating developed and produced by the Shanghai Institute of Organic Chemistry to protect the normal operating temperature environment of the spacecraft.
ZHSH Institute of Silicate has also undertaken the research and development of high-temperature resistant multilayer heat insulation materials, conductive low-absorption-radiation ratio flexible film secondary surface mirrors, and anti-static low-absorption-radiation ratio flexible film secondary surface mirrors.