Technical progress in landing mechanisms for exploring small solar system bodies

Landing on the surfaces of small solar system bodies (3SBs) is a prerequisite for maximizing the value of probes and provides technical reserves for the resource development of 3SBs and crewed landings on their surfaces. Motivated by the purposes of space exploration, such as finding the origin of life and developing space resources, launching probes and landing them on 3SBs is attracting increasing attention. The microgravitational environment and uncertain surface characteristics on 3SBs will contribute to the rebounding and tipping over of probes and thus pose great challenges to the landing of probes. In this paper, global deep space missions and plans to explore 3SBs are summarized, and the technologies related to landing mechanisms and sampling-cushioning assemblies are organized. The surface characteristics of 3SBs are important factors affecting the landing process of probes, so the achievements of the surface characteristics that have been obtained by scientific observations are reviewed, and theoretical research on mechanical properties is discussed. For more experience in the landing-cushioning of space probes, the existing landing structures and cushioning assemblies adopted for missions to other extraterrestrial bodies are studied, then their characteristics are analyzed and several novel approaches for landing on 3SBs are proposed. Subsequently, the microgravitational landing experiments and realization methods are sorted. Finally, some discussion about the future development of landing on 3SBs is presented. •Landing on the surface of small solar system bodies helps to maximize probes value.•Few probes have landed on the surface of small solar system bodies.•Microgravity and uncertain surface make challenges to the landing of probes.•Suppression of rebounding and tipping over of probes is crucial issues.•Both passive and controlled active landing-cushioning are worth solutions.