Research on design and cushioning performance of combined lunar landing airbag

Transportation of a large amount of goods and materials to the lunar surface will be an urgent need with the increasing intensive exploration of the moon. The airbag cushioning system is the most prospective one due to its low cost, simple structure, adjustable performance, and well stability, when compared to other types like the soft-landing mechanism and sky crane. The special lunar environment of the thin atmosphere and low gravity calls for new types of the combined airbag. Thus, a new combined airbag structure that can avoid generating a lot of dust during venting was proposed to fit the lunar environment. By proposing an improved deformation assumption of the airbag based on large deformation, as well as considering gas exchange between main and secondary airbags, a novel combined airbag analytical model was put forward. The inflation and cushioning process were calculated and validated through simulation analysis and ground test. The analytical, numerical, and experimental results were in good agreement. Using the analytical model, the lunar landing cushioning process of the combined airbag with different layouts was analyzed, and the optimal layout was determined. Furthermore, parameter effects on the cushioning performance were studied. The results show that: main airbag initial pressure, venting threshold pressure, vent orifice diameter, and secondary airbag volume have a great impact on cushioning performance, while inflation gas temperature has little impact. Notably, the influence law of these parameters is not monotonous.