The physical properties, sequence structure and heat flow of planetary regolith are important information to enhance the scientific understanding of lunar evolution and the origin of life, as well as for future planetary activities and resource utilization. An inchworm drilling system for planetary subsurface exploration missions is proposed in this paper. The inchworm drilling system consists of an inchworm drill and a chip removal device, and this paper provides a detailed description of the system design. Reasonable drilling parameters in the regular drilling condition are recommended based on drilling load analysis, and a manipulation strategy is given for troubleshooting in the faulty drilling condition. Robotic drilling experiments were carried out on a lunar regolith simulant, and the drilling depth of the inchworm drill reached 850 millimeters in 106 min. In addition, parameter identification tests of the simulant mechanical parameters were carried out during drilling, and the shear strength parameters of the simulant cohesion and internal friction angle at 5 locations along the depth direction were measured. The experimental results show that the proposed inchworm drilling system can well achieve the mission target of drilling and exploration and is a feasible choice for future planetary exploration missions.

In the past decade, the wireline robot has received increasing attention due to the advantages of light weight, low cost, and flexibility compared to the traditional drilling instruments in space missions. For the lunar subsurface in situ exploration mission, we proposed a type of wireline robot named IBR (Inchworm Boring Robot) drawing inspiration from the inchworm. Two auger tools are utilized to remove chips for IBR, which directly interacted with the lunar regolith in the drilling process. Therefore, for obtaining the tools drilling characteristics, the chips removal principle of IBR is analyzed and its drilling load model is further established based on the soil mechanical theory in this paper. And then the proposed theoretical drilling load model is experimentally validated. In addition, according to the theoretical drilling load model, this paper discusses the effect of the drilling parameters on the tools drilling moments and power consumption. These results imply a possible energy-efficient control strategy for IBR.

In order to solve the problems of locomotion interference and decline of traction force,reduce the abrasion of transmission parts caused by the environment restriction when the roller pipeline robot getting across the elbow,a drive tech-nology of roller pipeline robot with a mechanical adaptability named as tri-axial differential drive is studied.The mechanics principle of differential velocity of tri-axial mechanism is expatiated through the mechanics analysis.The traveling-capability of the tri-axial differential pipeline robot when getting across the elbow are validated through the theoretical studies on dif-ferential property and traction force of the robot.

In the Chang'E-5 mission of the lunar regolith drilling, the gap between the rotary drill bit and the sheath is required to be sealed. In view of the particularity of the lunar subsurface operation, a spiral seal method is proposed based on the analysis of the particles flow state in the clearance, which is made up of the spiral ribs on the inner surface of the drill bit and the friction interface on the outer surface of the sheath. The drilling and sampling simulation is carried out using discrete element method, which verifies the feasibility of the spiral seal in principle. For the test of sealing performance, a test system was developed and drilling and sampling experiments were carried out with several groups of sealing components that have different structure parameters. The test results show that the proposed spiral seal method solves the problem of regolith leakage well in the drilling and sampling process, and it will contribute to the design of the Chang'E-5 drill.

Planetary regolith conveying is an important process during planetary in situ resource utilization. After introducing finlike asperities on a longitudinally vibrated trough surface, we experimentally investigated the effects of vibration amplitude, frequency, and trough inclination angle on the particle flow state and directional conveying capacity. A numerical simulation based on the discrete element method (DEM) was then employed to study the detailed particle motion. Three flow states gradually appeared as the vibration strength increased: the particles remain stationary, flow down to the bottom of the trough, or directionally convey toward the discharge hole. The results indicated that the directional conveying capacity increased and decreased monotonically with increases in the vibration amplitude and trough inclination angle, respectively. The conveying capacity changed circuitously as the frequency increased and vanished when the frequency approached the resonant frequency of the trough. Additionally, according to the DEM simulation, breaking the force chains in the particle pile is necessary for conveying. The asymmetric force induced by the finlike asperities and its cumulative effect over time determines the particle flow state and conveying capacity. The particle flow velocity decreased as the granular layer height increased. This paper provides inspiration and guidance for designing a new type of conveyor for planetary regolith.

As the frozen soil in the South Pole region of the Moon is an important water resource, the operation of drilling and retrieving samples of the frozen soil in this region will be a crucial task for us to accomplish in future deep-space exploration. Thus, this paper investigated the effects of the increasing temperature and heat transfer between the drilling tools and the simulated lunar soil to minimize the degradation of the frozen soil samples during drilling due to the increased temperature. Specifically, the discrete element method was adopted and the heat transfer parameters of the discrete element particles were calibrated based on the equivalent heat transfer of the particle system. Moreover, a lunar soil particle system was developed for the simulations. Under the current working conditions with reasonable parameters, the maximum increase in the drill bit temperature was about 60 °C. Overall, the simulation results were consistent with the experimental results, and further analysis revealed that the flow of lunar soil can effectively take away thermal, which is also one of the reasons why the simulated lunar soil particles are in a high-temperature state at the front of the drilling tool.