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Some type of piercing into the subsurface formation is required in future planetary explorations to enhance the understanding of early stars’ geological evolution and the origin of life. Compared with other technical methods, drilling & coring, only utilizing the compound locomotion of rotation and penetration, can sample the subsurface soil relati...
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... Considering the limitations of the above sampling techniques, as a relatively efficient and convenient sampling technique, drill samplers or inertial impactor drills may play an important role in sampling the regolith of deep underground layers. These rotary drill samplers utilize the combined movement of rotation and penetration to complete sampling activities and can maintain the depth stratification information of samples to a large extent [24]. ...
... In addition, China Chang'e 5 used dry-type rotary drilling technology to transport regolith through hollow augers and used a novel flexible soft bag coring method similar to Luna 24 to recover samples [38]. Although this sampling technique has some advantages in maintaining stratigraphic stratification, it will inevitably destroy the in situ underground soil [24]. The design drilling depth of Chang'e 5 is 2 m. ...
As one of the most important parts of deep space exploration missions, the sampling technologies of extraterrestrial celestial bodies (ECBs) have attracted the attention and interest of many researchers. As a relatively efficient and convenient sampling technique, drill samplers have been applied in different ECBs exploration missions. Different from the previous drill apparatus, this paper introduces a novel automatic assisted drill system (AADS), which is used to sample the deep layer regolith of ECBs. This drilling system can sample the deep regolith layer under manual assistance or unmanned automatic operation mode. The sampler has improved and designed a segmented detachable coring pipe, drilling pipe and casing pipe. It can largely maintain the layer information in the depth direction of the ECBs regolith and can also automatically change the drill sampling process through the driller change system to improve the sampling efficiency. Finally, an automatic test apparatus was designed, and an experimental platform was established to conduct a drill sampling test for the AADS sampler. The experimental results show that the AADS sampling system can successfully obtain at least 2.4 m depth and 1.1 kg weight simulated regolith samples.
... The explorations of the Moon, Mars and other extraterrestrial bodies have extremely high scientific and economic value for the study of the evolution of the solar system, the origin of Earth, and the evolution of life (Gao and Chien, 2018;Tang et al., 2017;Zhang et al., 2021). Furthermore, exploitation of the mineral resources in extraterrestrial bodies could effectively resolve humanitys energy problems (Zhang et al., 2019;Bar-Cohen and Zacny, 2020;Zwierzynski et al., 2021). ...
... Finally, we determined to prepare the lunar regolith simulant with the ratio of anorthosite and basalt at 7:3, through three steps of particle size screening, grading, and drying [31][32][33]. The particle size gradation ratio of lunar regolith simulant is shown in Table 3. ...
The collection of lunar regolith with complete stratigraphic information is the key to analyzing the evolution and composition of the moon. To keep each sample’s stratification for further analysis, a sampling method called flexible-tube coring has been adopted for Chinses lunar explorations. Given the uncertain physical properties of lunar regolith, drilling force and core lift force should be adjusted immediately in piercing process. Otherwise, only a small amount of core could be sampled, and overload drilling faults could occur correspondingly. Due to the fact that the cored regolith is inevitably connected to the flexible tube, coring characteristics may have a great influence on both lifting force and sampling quantity. To comprehend the regolith coring characteristics, a flexible-tube coring motion mechanics model was established and verified to acquire the lifting force results accurately. Herein, the judgment conditions for the flexible tube crawling phenomenon are proposed. Finally, the accuracy of the model is verified by comparing it with the Chang’e V telemetry data. This article provides theoretical support for the design and regulation improvement of Chang’e VI drilling and coring in the future.
... At present, the main task of the lunar exploration project is the sampling and return of lunar soil [1], in which drilling sampling is the preferred method to achieve lunar soil sample collection. Sampling drilling tools for lunar drilling are generally hollow spiral drilling tools, with a sampling port at the front of the drill bit [2]. In the early experiments, it was found that the lunar soil particles have a great influence on the sampling process, especially when the drilling tool encounters particles with a critical particle size close to the size of the drill bit, it will cause a large load change. ...
Critical size lunar soil particles refer to particles with a particle size similar to the diameter of the drill bit, which is an important factor affecting lunar soil drilling sampling, and its influence is uncertain. In this paper, the discrete element method is used to simulate the drilling sampling process of the critical size lunar soil particles and the influence of the size, position and shape of the lunar particles with critical diameter on the drilling load is analysed. It is found that the critical size lunar soil particles have special migration trajectories and load characteristics during drilling sampling. The size and shape of lunar soil particles are the key factors affecting the drilling load. This study can support the design of drilling tools for lunar soil exploration and sampling.
... However, it is normally impossible to obtain samples without disturbance since the lunar soil is a kind of loose aggregate composed of particles, which has some flowing characteristics and is easy to appear relative sliding [7,8]. Thus, the original bedding information of the lunar soil samples will be inevitably disturbed by the sampling tools in many sampling methods, including the excavating and shoveling method [9][10][11], the hard tube coring method [12][13][14] and the FTC method [15]. ...
In order to understand the geological information of the moon and explore the components of lunar soils and their property of bedding distribution, taking lunar soil samples back to Earth is one of the most important tasks in modern unmanned lunar exploration project. However, because of the inherent flowing characteristics of lunar soil, the disturbance of their original bedding information is inevitable in the course of the coring process, which needs to be known quantificationally. Considering the limited researches on the bedding disturbance of soils at present due to the complicated technique difficulties, this paper aims to perform the disturbance analysis of the soil bedding information for flexible tube coring (FTC) by combining theoretical, numerical, and experimental methods. Firstly, a theoretical model of universality, considering the variation of lunar soil cohesion and internal friction angle with the depth, is established for investigating the disturbance. Thereafter, a novel method, named the curve slope (CS) method, is proposed to quantificationally describe the degree of bedding disturbance of the soil samples at different depths. Furthermore, a numerical simulation model referring to structural dynamics, soil mechanics and large deformation of flexible body is efficiently constructed and solved by coupling FE (Finite Element) and ALE (Arbitrary Lagrange-Euler) methods achieved via nonlinear finite element code LS-DYNA. A simplified experiment is finally conducted to verify the proposed theoretical method. Both the numerical and experimental results are in good agreement with the theoretical one in terms of disturbance phenomenon of soil samples evaluated by the displacements, revealing the validity and accuracy of the theoretical model. The findings from this study can provide practical and important guidance for analyzing the disturbance of original bedding information of lunar soil samples in engineering applications.
... Furthermore, considering that besides the drilling loads the online coring morphology and final coring results may also be influenced by the uncertain properties [14], for future unmanned planetary sampling probes, appropriate operating parameters should be matched with the current drilling formation, whether it is granular soil or hard rock. Otherwise, serious drilling faults, e.g., auger choking, bit inclusion, etc. [15,16], and low coring results could both easily happen under unsuitable drilling parameters [17,18]. Therefore, to enhance the understanding of the interaction between drill tool and lunar regolith, a large number of ground drilling and coring experiments should be conducted. ...
Compared to other technical methods, drilling and coring by only using
the compound motions of rotation and penetration can sample subsurface lunar soils relatively efficiently. Considering that drill tool’s power consumption and soils’ coring morphology are both determined by external operating parameters and physical properties of in-situ soils, the influence by drilling parameters on a certain formation should be investigated firstly. To remove the coupling effect by lunar soils’ physical properties, one type of homogeneous lunar soil simulant along the longitudinal direction is urgently necessary
for verification experiments. Herein, a dynamic-compacting based lunar soil simulant preparation method is proposed to tamp the raw soil material into a relatively dense and uniform state. A group of optimized lunar soil preparation parameters has been acquired by analyzing the dynamic interaction process. Experiments under a high speed camera’s online monitoring indicated that under over 12 cycles of tamping the raw soil can be compacted into a homogeneous state along about 200 mm depth, which is consistent with the analytical results. The longitudinal density of the compacted soil simulant is also close to the value of lunar soil. Therefore, further orthogonal sampling experiments will be conducted in this lunar regolith simulant.
... Hitherto, studies have conducted by mainly focusing on the auger and the drill bit. Tang et al. [11,12] investigated the flowing characteristics of flexible tube coring in lunar sampling. Quan et al. [13,14] considered the auger and the recovery rate in planetary sampling and developed a new drilling load modeling and performed the corresponding valida- tion. ...
A tubular woven bag covering a rigid tube, known as a crucial component in flexible tube coring system adopted for future lunar soil coring missions, which dynamic performance, especially the stick-slip behavior, might largely affect the reliability and quality of the lunar soil coring, should be explored in depth. Here we have developed analytical formulation and high fidelity finite element (FE) model to investigate the stick-slip behavior of the tubular woven bag covering a rigid tube in the turning inward process. The theoretical model is established via dividing the whole process into the unfolding and the detaching periods. The FE model is efficiently established and solved by using nonlinear finite element code LS-DYNA. Results show that good agreements can be realized between the numerical results and the theoretical ones. Moreover, based on the developed theoretical model, parametric analysis of the stick-slip process is performed to quantify the effects of the key parameters, including the mass, damping and stiffness of the woven bag, the driving velocity, the pressure on the bag, and the initial wrinkle ratio, on the stick-slip behavior. The findings from this study can provide practical and important guidance for designing the deep lunar soil coring system with high stability and reliability.
... Despite these advantages, there are still some drawbacks in flexible tube coring and a series of relevant research has been conducted. Several methods have been developed to control the system for coring automatically and monitor the coring process for avoiding breakdowns [14][15][16]. To obtain high filling rate of the soft bag to get more soil samples [17], structural optimization was performed to the coring system, in which parameters of the components such as the auger [18,19] and the drill bit [20,21] have been optimized. ...
A tubular soft bag covering a rigid tube, known as a coring system, is a key tool in deep lunar soil coring. The dynamic performance of the coring system is of critical importance, largely determining the quality and efficiency of the lunar soil coring. The main contribution of this study focuses on analyzing the mechanism of the force dragging the soft bag in the dynamic process of the simulated lunar soil coring analytically, numerically and experimentally. By adopting the combination of mechanism analysis and experimental study, a novel mechanical model of the dragging force is founded. Using this mechanical model, the process of deep simulated lunar soil coring can be divided into three stages. Besides, the whole dynamic process of the simulated lunar soil coring is simulated by coupling Finite Element (FE) and Smoothed Particle Hydrodynamics (SPH) methods using the nonlinear finite element code LS-DYNA. The numerical simulation results show that the flexible tube coring system provides advantageous performance, and its dynamic performance is in accordance with the theoretical analysis. To further evidence the effectiveness and accuracy of the mechanical model and the numerical simulation , a special test-bed for soil coring is built and experiments are conducted. It can be found that results obtained from these three methods are in good agreement. The findings from this study can provide a directive and practical guidance to improve the safety and reliability of the deep soil coring system.
... Different from some other technical methods, such as explosion, melting, excavating, drilling and coring, only using the compound motion of rotary and penetration, has its unique advantages in piecing into the subsurface soil ( BarCohen and Zacny, 2009). Hence, this convenient method has been widely applied to previous planetary explorations, such as Apollo, Luna series ( Tang et al., 2017). ...
... According to soil's reinforcement theory, soil's compaction effect is greatly determined by the mass of tamp Gt, the height of tamp Ht, the tamp times Nt, and the number of soil's layers nl. Herein, by selecting suitable polytechnic parameters (Gt = 3 t, Ht = 250 mm, Nt =12, nl = 1), the raw material is made into a compacted and definable state ( Tang et al., 2017). Cutting ring density tests showed that the density of simulant fluctuates between 1.94 g/cm 3 and 2.02 g/cm 3 along the longitudinal direction, which can be roughly considered as a homogenous state. ...
Seeking the evidence of potential life is one essential and perpetual driving force for human planetary explorations. Compared with other technical solutions, sampling the planetary soil and returning it back to Earth for further analyzing may be the most direct method to realize this goal. Due to the fact that sample’s geological stratification along the longitudinal direction completely records early stars’ geological evolution, it should be better to adopt suitable sampling methods to preserve the whole sample well. Flexible tube coring (FTC) method, applying a series of hollow coring tubes into the auger to sample the subsurface regolith, can preserve sample’s geological stratification without any losses, hence it has been adopted in the China Chang’e III project. However, it should be noted that the final coring results and online drilling loads that drill tool sustained are both greatly influenced by the uncertain physical properties of lunar regolith, hence proper drilling parameters should be tuned immediately in drilling process. Otherwise, only a small amount of cored soil sample would be acquired and serious overloads drilling faults could occur correspondingly. In order to comprehend the soil flow characteristics and avoid potential drilling faults, a novel soil flow characteristics monitoring method was proposed by employing an ultrasonic sensor and an industrial camera to monitor the coring results and removal states. Experiments in one typical lunar regolith simulant revealed that penetration per revolution has great influences on drilling states and should be optimized further.
... Therefore, the authors proposed a novel flexible tube coring method to preserve the stratification of soil sample [29]. In order to comprehend the core flowing characteristics and optimize the final coring results, a non-contact type measurement based on ultrasonic wave reflection mechanism and vision techniques is applied to online monitor the coring and removal characteristics [30]. Once the drill-soil interaction comprehended, suitable drilling parameters for different drilling formations considering both power consumption and coring morphology can be optimized then. ...
The robotic technology, especially the intelligent robotics that can autonomously conduct numerous dangerous and uncertain tasks, has been widely applied to planetary explorations. Similar to terrestrial mining, before landing on planets or building planetary constructions, a drilling and coring activity should be first conducted to investigate the in-situ geological information. Given the technical advantages of unmanned robotics, utilizing an intelligent drill tool to acquire the planetary soil sample may be the most reliable and cost-effective solution. However, due to several unique challenges existed in unmanned drilling and coring activities, such as long-distance time delay, uncertain drilling formations, limited sensor resources, etc., it is indeed necessary to conduct researches to improve system's adaptability to the complicated geological formations. Taking drill tool's power consumption and soil's coring morphology into account, this chapter proposed a drilling and coring characteristics online monitoring method to investigate suitable drilling parameters for different formations. Meanwhile, by applying pattern recognition techniques to classify different types of potential soil or rocks, a drill-ability classification model is built accurately to identify the current drilling formation. By combining the suitable drilling parameters with the recognized drillability levels, a closed-loop drilling strategy is established finally, which can be applied to future interplanetary exploration.
