As millions of people watched in awe and excitement as the combined lander-ascender of China’s Chang’e-5 spacecraft touched down successfully on the moon's surface and unfolded its solar panels, researchers from the Space Mechanics Team of Tianjin University cheered with a mixture of pride and relief.

As part of the group which had worked to ensure the lunar probe’s successful landing, the research team led by Professor Cui Yuhong and Professor Wang Jianshan had been engaged in building an experimental test landing site which could simulate the extraterrestrial lunar body.

“We designed and built a simulated moon surface with multiple lunar terrains like rocks, craters and slopes, and offered more than 20 terrain combination options, according to technical parameter requirements,” said Prof. Cui Yuhong.

On the trial ground, the team then simulated the gravity of the moon, about one-sixth that of the gravity on Earth, to test the force and deformation of the lander's soft-landing design.

They developed a 1/6G gravity simulation slope that can not only simulate the friction coefficients of various surface obstacles like rocks, craters and the different landing surfaces of the lunar surface, but can also withstand the landing impact of a model weighing several tons, meeting strict requirements on the geometric characteristics, stiffness, elastic modulus and surface friction index of the simulated lunar surface.

Another contribution the team made to the mission was their study of the interaction between a rocket plume and lunar dust, which influenced the design of Chang’e-5 probe’s soft-landing control system.

“The lunar surface was eroded by the exhaust plume and a large amount of lunar dust was forced into a high-velocity spray. This high-speed lunar dust can have many adverse effects on the normal operation of the lunar landers like blocking the sights and damaging facilities,” Prof. Wang Jianshan said. “Our research proposed a gas-particle two-way coupled method for simulating the interaction, which proved quite credible after its results were compared with Apollo lander measured data and other simulation results and showed close similarities.”

The Space Mechanics Team of Tianjin University has participated in national major science and technology projects such as the "lunar exploration project" and the "Mars exploration program" over the last decade. Their research methods and achievements have been adopted by the Chang'e-3, 4 and 5 landers, and will also be applied to future Chang'e landers, providing important research methods and reference data for China's lunar exploration project.