10:00 AM - 10:15 AM
[PPS08-05] Development of lunar surface geotechnical investigation system
★Invited Papers
Keywords:Lunar regolith, Physical and mechanical properties, Geotechnical Investigation, Robotic exploration, Lunar base construction
The lunar surface is covered by a layer of soil known as regolith, which remains largely unstudied from a soil mechanics perspective. Significant uncertainties also exist regarding the geology and topography, posing risks to the safety and efficiency of lunar surface operations. In addition to the unique properties of regolith, design methods for exploration robots and lunar base construction under low gravity and high vacuum conditions have yet to be established, resulting in high risks for lunar surface activities. To ensure sustainable lunar exploration and future lunar base construction, in-situ geotechnical investigations, similar to those conducted in terrestrial construction, are essential.
To address these challenges, we are developing an unmanned exploration robot, the Robotic Geotechnical Investigation System (RGIS), designed to gather critical data on the lunar surface and implement geological and geotechnical risk management. The RGIS is equipped with four key components:
(a) Positioning and Surveying Tool: This system integrates multiple monocular cameras, oriented in different directions, with LiDAR to perform 3D positioning and surveying. Spherical markers, acting as feature and reference points, are randomly placed on the lunar surface. As the rover moves, it captures and extracts point clouds of these markers via LiDAR for reference point positioning through SLAM processing. Simultaneously, 3D topographic mapping is conducted using images captured by the multi-directional cameras through SfM/MVS processing. By integrating the scale information of the reference points extracted by LiDAR, a high-density point cloud of the microtopography is obtained.
(b) Seismic Exploration Tool: This system performs seismic exploration (primarily surface wave exploration) using an ultra-compact array, consisting of a vibrator and geophones mounted on a 1-meter-long horizontal arm. The array is deployed and retracted by the rover to ensure proper surface contact or retrieval of the vibrator and geophones. By conducting measurements at multiple points, the system generates a spatial distribution map of the S-wave velocity structure (bulk density distribution of the regolith) down to a depth of approximately 1.5 meters.
(c) Loading and Shear Testing Tool: This testing system evaluates the mechanical properties of the surface regolith by pressing a 5 cm-diameter plate disc onto the ground. The system conducts two types of tests:
Loading Test: Measures settlement by applying vertical force to the plate disc to determine soil deformation parameters, such as the ground reaction coefficient and deformation modulus.
Shear Test: Applies a predetermined loading pressure and rotates the plate to measure torque (shear force), enabling the determination of soil strength parameters, such as cohesion and internal friction angle.
(d) RI Density Meter: This system measures the bulk density of the surface using a radioactive isotope (RI). The measuring device, which integrates the radiation source and detector, is placed on the ground to emit gamma rays into the subsurface and measure the attenuation characteristics of the scattered gamma rays.
Data collected by the RGIS will allow the construction of a three-dimensional geological and geotechnical map of the lunar surface. This map will support the prediction of exploration vehicle behavior, construction robot operations, and the design of earthworks, such as excavation, filling, leveling, and module/structure installation. The data will also aid in risk management for lunar surface operations, enabling the safe and efficient design and implementation of construction tasks.
Acknowledgment: This research was supported by the MLIT R&D Program for the Project of Technological Innovation for Construction in Space.
To address these challenges, we are developing an unmanned exploration robot, the Robotic Geotechnical Investigation System (RGIS), designed to gather critical data on the lunar surface and implement geological and geotechnical risk management. The RGIS is equipped with four key components:
(a) Positioning and Surveying Tool: This system integrates multiple monocular cameras, oriented in different directions, with LiDAR to perform 3D positioning and surveying. Spherical markers, acting as feature and reference points, are randomly placed on the lunar surface. As the rover moves, it captures and extracts point clouds of these markers via LiDAR for reference point positioning through SLAM processing. Simultaneously, 3D topographic mapping is conducted using images captured by the multi-directional cameras through SfM/MVS processing. By integrating the scale information of the reference points extracted by LiDAR, a high-density point cloud of the microtopography is obtained.
(b) Seismic Exploration Tool: This system performs seismic exploration (primarily surface wave exploration) using an ultra-compact array, consisting of a vibrator and geophones mounted on a 1-meter-long horizontal arm. The array is deployed and retracted by the rover to ensure proper surface contact or retrieval of the vibrator and geophones. By conducting measurements at multiple points, the system generates a spatial distribution map of the S-wave velocity structure (bulk density distribution of the regolith) down to a depth of approximately 1.5 meters.
(c) Loading and Shear Testing Tool: This testing system evaluates the mechanical properties of the surface regolith by pressing a 5 cm-diameter plate disc onto the ground. The system conducts two types of tests:
Loading Test: Measures settlement by applying vertical force to the plate disc to determine soil deformation parameters, such as the ground reaction coefficient and deformation modulus.
Shear Test: Applies a predetermined loading pressure and rotates the plate to measure torque (shear force), enabling the determination of soil strength parameters, such as cohesion and internal friction angle.
(d) RI Density Meter: This system measures the bulk density of the surface using a radioactive isotope (RI). The measuring device, which integrates the radiation source and detector, is placed on the ground to emit gamma rays into the subsurface and measure the attenuation characteristics of the scattered gamma rays.
Data collected by the RGIS will allow the construction of a three-dimensional geological and geotechnical map of the lunar surface. This map will support the prediction of exploration vehicle behavior, construction robot operations, and the design of earthworks, such as excavation, filling, leveling, and module/structure installation. The data will also aid in risk management for lunar surface operations, enabling the safe and efficient design and implementation of construction tasks.
Acknowledgment: This research was supported by the MLIT R&D Program for the Project of Technological Innovation for Construction in Space.