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• A numerical model is established to study the influence of anchor rod configuration on anchoring performance. • Anchoring experiments with different anchor rods are carried out to verify the numerical model's accuracy. • The anchoring performance of the anchor rods with different configurations is analysed. • The optimal anchor rod configuration is obtained by optimising the numerical model. Due to the microgravity environment of the asteroid surface, the asteroid probe needs to connect with the asteroid surface by an anchoring device to provide enough anchoring force for in situ exploration. Compared with other anchoring methods, drilling anchors have the advantages of adaptability, reliability, and reusability. The anchor rod is the key component of the drilling anchor, and its configuration directly affects the anchoring performance. A numerical model is established based on cavity expansion theory to investigate the influence of the anchor rod configuration on the anchoring performance. Five kinds of anchor rods with different cross-section shapes are selected to conduct anchoring experiments. The numerical model calculation results are compared with the experimental results to verify the numerical model's accuracy. The anchoring performance of the anchor rod with different cross-sections, rotation angles, axial sections, and torsion angles is analysed. The optimal anchor rod configuration is obtained by optimizing the numerical model. The anchor rod with a rectangular cross-section and axial-section and no torsion has the best anchoring performance. This work provides a new approach to calculate and evaluate the anchoring performance of various anchor rod configurations of anchoring devices during the asteroid exploration process. [ABSTRACT FROM AUTHOR]

• A numerical model is proposed to predict the ultimate uplift capacity of the anchoring rod of the anchoring devices. • The geomaterial behavior and the ultimate uplift capacity under the microgravity environment are analyzed by DEM simulation. • Calibration experiments calibrate the parameters of three typical geomaterials. • The distribution of loaded particle forces in the geomaterials under various anchoring conditions is compared and analyzed. • The error between the numerical model prediction results and the DEM simulation results is less than 5%. Due to the microgravity environment on the asteroid surface, the asteroid probe can not stay on the asteroid surface for a long time for in situ exploration. Therefore, an anchoring device is required to provide enough ultimate uplift capacity to hold the asteroid probe on the asteroid's surface. In this work, based on the circular arc failure surface hypothesis, a numerical model is proposed to predict the ultimate uplift capacity of the anchor rod of the anchoring devices during the anchoring process. The discrete element method (DEM) simulation is adopted to calculate the ultimate uplift capacity and analyze the geomaterial behavior. To accurately simulate material properties, the parameters of three typical geomaterials are calibrated by the calibration tests. The anchoring experiment verifies the DEM simulation results, and the error between the anchoring experiment results and DEM simulation results is less than 14%. The distribution of loaded particle forces in the geomaterials under various anchoring angles(30°–60°) and the anchoring depths(20 mm–40 mm) in the simulation are compared and analyzed. Compared with the DEM simulation results, the ultimate uplift capacity's numerical model prediction results have an error of 5%. This work provides a new approach to predict the ultimate uplift capacity of the anchor rod of the anchoring devices during the asteroid exploration process. [ABSTRACT FROM AUTHOR]

Asteroid probes require an anchoring device for in-situ detection to overcome the environment of microgravity on asteroid surfaces. The configuration parameters of the probe will affect the anchoring performance of the drilling anchoring device. In this work, a kinetic model of the anchoring failure process is established, the configuration parameters of the probe that affect the anchoring failure process are obtained, and the sensitive parameters affecting the anchoring failure process are selected based on the Sobol method. A discrete element method (DEM) model is established to calculate the anchoring force of the probes with different sensitive parameters under three force conditions. The central composite design (CCD) method is used to fit and analyze the DEM simulation results, and the influence of sensitive parameters on the anchoring force is obtained. This work provides a new approach for calculating and evaluating the anchoring force of various asteroid probe configurations. It gives a reference for the configuration design of the probe from the anchoring perspective. [Display omitted] • Sensitive parameters affecting anchoring force are selected by kinetic modeling. • A discrete element model is developed, and its accuracy is verified experimentally. • The effect of sensitive parameters on anchoring force is obtained by simulation. • The forces on the particles reveal the mechanism of anchoring force variation. [ABSTRACT FROM AUTHOR]

Asteroid anchoring is the premise for the spacecraft to conduct in-situ scientific exploration on the surface of a weak gravitational asteroid. There is not any precedent for successful anchoring on the asteroid surface all over the world. Ultrasonic drill actuated by the piezoelectric ceramic is especially suitable for drilling on the surface of a weak gravitational asteroid, showing outstanding advantages such as low power consumption, low required drilling pressure and wide temperature range. In order to solve the technical problem of anchoring, a novel anchoring device based on multiple ultrasonic drill cross-drilling geometric force closure is proposed. Firstly, the structure and working principle of the anchoring device are introduced. Then the EDEM software based on the Discrete Element Method is used to simulate the influencing factors of the anchoring force. Finally, the effectiveness of the anchoring device is proved by experiments. The results show that the ultrasonic drill is effective for the anchoring device; the anchoring device can provide an anchoring force of 60–250 N for the spacecraft; its structure is simple, compact and adaptable. • This paper focuses on the method of long-term anchoring of the spacecraft on the asteroid surface. • A novel anchoring device based on multiple ultrasonic drill cross-drilling geometric force closure is proposed. • EDEM model is built to predict the influencing factors of the anchoring force. • A testbed is established to measure the effect of media with various compressive strengths on the anchoring force. [ABSTRACT FROM AUTHOR]