This study analyzes the surface sliding behavior of space probes in simulated extraterrestrial environments. When a space probe lands on an extraterrestrial body, its landing gear (footpad, landing legs) contacts and slides along the ground surface. The influence of various parameters (i.e., footpad size, velocity, ground condition, atmospheric pressure, and gravity) on the friction behavior of footpads was experimentally evaluated herein. First, we developed an experimental system that can perform footpad sliding tests repeatedly. Subsequently, the system was used to perform tests under various conditions: 1) on ground under normal atmospheric conditions, 2) in a vacuum, and 3) in reduced gravity. The tests performed in a vacuum and in reduced gravity indicated that the friction behavior of the footpad is largely unaffected by atmospheric pressure and gravity. The findings obtained herein offer useful design and control guidelines for space probes landing on extraterrestrial bodies.

This paper presents a novel approach to sampling subsurface asteroidal regolith under severe time constraints. Sampling operations that must be completed within a few hours require techniques that can manage subsurface obstructions that may be encountered. The large uncertainties due to our lack of knowledge of regolith properties also make sampling difficult. To aid in managing these challenges, machine learning-based detection methods using tactile feedback can detect the presence of rocks deeper than the length of the probe, ensuring reliable sampling in unobstructed areas. In addition, given the variability of soil hardness and the short time available, a corer shooting mechanism has been developed that uses a special shape-memory alloy to collect regolith in about a minute. Experiments on subsurface obstacle detection and shooting-corer ejection tests were conducted to demonstrate the functionality of this approach.

This paper presents a high-speed transportation of capsule by launch. One of the main issues for the transportation is how to decelerate the capsule during its flight to avoid a large landing impact. In order to stop the capsule temporally in the air just before its landing, we propose a flight control method by multidirectional tension of wires. Since the capsule is connected with both auxiliary weights and reel system via wires, it can be geometrically constrained not to move by multiple pull of the wires. We develop the motion planner which makes the capsule reach the target at the desired speed, and control algorithm for it. The proposed method is applied to the soft landing of the capsule. The effectiveness of the proposed method is verified through the experiment.

Supposing a space mission of setting monitoring devices at suitable positions on the moon, we discuss how to apply a casting manipulation to the mission. This paper addresses a mechanism of a casting manipulator system and control method to launch a penetrator to the desired position. First, we discuss launching methods, and focus on a method by using rotation of a boom. We then propose the mechanism that keeps a posture of the penetrator equipped at the tip of the boom constant for the absolute coordinate system during its rotation. This mechanism prevents the wire which connects the penetrator and the robot's base from winding the boom. Analyzing a position error of landing point caused by delay of releasing the penetrator, we propose the motion control of the boom to reduce the error. Finally, we develop the system and verify the effectiveness of the proposed method through experiment.

In this paper new procedures for the measurement of mobility parameters, such as contact pressure, and an analysis of a low-pressure wheel model on deformable terrain, are presented. Because the lunar surface is covered by regolith which implies an irregular and rough terrain, the rover has difficulty in moving. Therefore a new low-pressure wheel is recommended for high mobility performance and low power consumption with a less complex mechanism. A low-pressure wheel can change its contact shape and pressure distribution to account for terrain. The presented measurement is achieved by a new measurement instrument on the wheel, and we presented analysis model is conducted through analysis of terramechanics mobility dynamics of a low-pressure wheel with normal stress. These procedures are valuable for evaluating the longitudinal velocity of the low-pressure wheel on deformable terrain.

This paper presents the manipulator with the new joint which can passively switch free state to drive state and vice versa. The manipulator with the free-state joint is categorized as a system subjected to a nonholonomic constraint; hence, its smooth feedback control cannot be implemented. In this paper, the issues on its control are clarified through the test with the experimental setup of the manipulator with a free joint. The manipulator with the switching joint is also developed and its effectiveness is verified through the experiment. Consequently, the trivial actuation using the proposed joint accomplishes more precise positioning in the experiment.

This paper describes the mathematical modeling and the propulsive characteristics of a novel robot driven by Archimedean screw mechanisms, named Screw Drive Rover. For secure locomotion on soft soil, the proposed rover would become one of the good solutions because of its robustness to slipping and getting stuck in the soil. Furthermore, the rover is expected to move in various directions by using the dual screw units. However, the interaction between such screw unit and the surrounding soil is quite complicated and remains undefined. So, this paper attempts to model the tractive effort of the rover on the soil. The mathematical modeling is newly developed based upon terramechanics, addressing soil-vehicle interactive mechanics. Finally, the validity of the proposed model is demonstrated by simulation analyses.

Hayabusa spacecraft performed the final descents and touchdowns twice in November 2005. In final descent phase, terrain alignment maneuvers were accomplished to control both altitude and attitude with respect to the surface by using four beams Laser Range Finder onboard. Then Hayabusa spacecraft made dynamic touchdowns the surface of the asteroid by the sampler system to collect samples automatically. This paper presents the terrain alignment maneuver and touchdown scheme. This paper also describes the novel sample horn system and touchdown dynamics. Touchdown tests on the ground are presented. Then the flight results on descent and touchdown dynamics are shown and discussed.

Subsurface exploration on the Moon is a significant mission for future space developments. The authors have studied an autonomous robotic explorer which can burrow into the soils. This paper focuses especially on the excavation mechanism of a burrowing robot for near-future lunar subsurface exploration. The main objective of the proposed robot is to bury a scientific observation instrument, such as a long-term seismometer under the lunar surface, which is covered with very compacted lunar regolith. Therefore, an efficient drilling mechanism is required. In this paper, the authors propose a non-reaction screw drilling mechanism with double rotation, which is called the contra-rotor screw. This paper also evaluates the feasibility and effectiveness of the proposal of a burrowing robotic system through some experimental analyses.