In this paper，scientific objectives and payloads configuration of international asteroid exploration missions in the past three decades were reviewed. On the basis of summarizing the main scientific questions of asteroid exploration， the selection of detection objects，scientific objectives and payloads configuration of China’s asteroid exploration project，which named Tianwen-2 mission were discussed. Focusing on the realization of scientific objectives，corresponding scientific research contents and payload technical specifications were proposed.

Lava tubes, formed by the flow and cooling processes of volcanic lava, have been discovered on the surface of several heavenly bodies in the solar system and have become a window into the volcanic activity and thermal history of Earth-like planets. At the same time, lava tubes have extremely important scientific and engineering applications because of their thermostatic and radiation-proof interiors, which are also natural shelters for future human exploration activities or extraterrestrial survival. In this paper, the formation mechanism, detection and identification methods of lava tubes, and the distribution of lava tubes on the surface of different heavenly bodies in the solar system were summarized, the scientific significance and application prospects of lava tube detection were discussed. It was proposed that the Earth’s lava tubes are the most important objects for planetary lava tube analogical studies and detection, and the theory and methodology of the analogical studies of lava tubes were introduced, to provide theoretical basis and simulation experimental support for future exploration of extraterrestrial lava tubes.

The principle of radio frequency ion thrusters（RIT），as well as the research history and achievements of micro-newton and milli-Newton RIT at home and abroad in the past 60 years，was explained in detail. The radio frequency ion propulsion system involves a number of key technical challenges. Preliminary solutions to the problems of propellant selection， radio frequency（RF）circuit impedance matching，gas flow control，electrical neutralization control and lifetime were proposed， and the development trend and research direction were put forward combined with the future application of RIT.

For the detection of lava tubes on extraterrestrial bodies, this paper utilizes LiDAR technology to conduct field surveys on lava tubes in the Shishan Volcanic Cluster area of Haikou City, which has a high degree of similarity with the Moon and Mars. It also proposes a skylight detection method based on grid division and applies a crack detection method based on data enhancement and multi-scale feature learning network to detect the internal structure of the lava tube and study its morphology. The interior of the lave tubes is scanned in all directions using a portable handheld laser scanner in the first. Based on the high-precision point cloud data obtained by measurement, this paper completes a three-dimensional model using the ContextCapture software, and some special miniature geomorphic like skylight in the tube and the tubes’ inner fissure is detected and extracted automatically. The experimental results show that the laser scanner combined with point cloud processing software and program can efficiently, intuitively and truly restore the morphology and structure of the lava tube, conduct quantitative analysis, and detect the special miniature geomorphology in the tube.

The stable celestial geological structure，the suitable distance from the Earth to the Moon，and no dense atmosphere and global magnetic field make the Moon a natural and excellent laboratory for the monitoring and research of the Sun-Earth-Moon space weather. This paper reviews the progress of lunar space weather detection and research，and surveys the key scientific problems of lunar space weather and the problems of its prediction application，proposes the concept of the Moon-based space weather monitoring station，set up the specific scientific objectives of the monitoring station，and finally introduces its three major systems and the relationships among them，including the monitoring system，the scientific research system，and the modeling and forecasting system. The establishment of a Moon-based space weather monitoring station is of great scientific significance for studying the mechanism of solar eruptions，the coupling of the Sun to the Earth and the Moon，and the local variations of the Moon’s environment. It will also promote the development of lunar space weather modeling and prediction technologies and improve the capability in providing space environmental safeguard services for future lunar explorations.

This paper, founded on the synthesis of recent exploration achievements and prior research, supplemented by on-site investigations of diverse terrestrial lava tubes, delves into the value and challenges associated with lunar lava tube exploration and development. Employing lunar remote sensing data and focusing on lunar lava tubes in areas such as Mare Fecunditatis and Mare Tranquillitatis, the paper formulates a collaborative exploration blueprint comprising lunar landing platforms, rovers, and autonomous robots. Furthermore, in line with the objective of utilizing natural cavities within lava tubes for potential lunar base construction, the paper scrutinizes the prerequisites and complications linked to lava tube modification and construction. It presents conceptual solutions, encompassing cave interior floor construction, communication and power infrastructure deployment, as well as residential facility establishment, providing a fundamental reference for the construction of future lunar bases.

Based on the phenomenon of single-side local high temperature of throat and high jump of weld temperature during steady-state test ignition of the engine. which seriously endangers the reliability of the engine，CFD simulation was used to model the structure of the head injector and optimize the distribution structure in the flow channel combined with the flow resistance mathematical model. To achieve the reduction of jet flow resistance and improve the non-uniformity of flow caused by impact，and optimize the combustion structure and liquid film cooling scheme in the side zone by adjusting the impact parameters，optimize the mixing ratio in the side zone，and reduce the throat temperature and circumferential temperature difference. The improved engine has been verified by experiments. Under the condition of unchanged performance，the temperature of the high-altitude simulated thermal test throat was reduced from nearly 1 500 ℃ to 1 270 ℃，the temperature at the headbody weld was reduced from 520 ℃ to 310 ℃，and the temperature difference of the engine body was controlled within 50 ℃，which effectively solved the problem of high temperature in the engine throat. The service life and reliability of the engine were improved.

Lava tubes are one of the prime candidates for establishing extraterrestrial bases. To verify the feasibility of using ground-penetrating radar to detect lava tubes on extraterrestrial bodies, this paper first conducted a technical study to validate the detection of lava tubes using a 400 MHz ground-penetrating radar system on the Seventy-Two Caves and Wolong Cave in the Shishan Volcanic Group in Haikou, Hainan. It is found that the upper interface of the lava tube is clearly displayed when the depth of the tube is 2 m, and the radar image shows the upper and lower boundaries when the height is less than 3 meters. Additionally, the genetic algorithm is employed to inverse the dielectric constant of the lava tube’s wall. The reliability of the genetic algorithm in calculating the dielectric constant is validated through comparison with results obtained from the depth method and sample measurement. Furthermore, the analysis of samples establishes a simple relationship between porosity and dielectric constant. These findings are of significant importance for assessing the underground spatial distribution and wall stability of the lava tubes, providing a reference for future lunar base establishment.

To address such the problems as the limitation of the invisible zone of the ground-based monitoring system for near-Earth asteroids and the insufficient discovery and cataloguing capabilities of the monitoring system，a solution of a space-based distant retrograde orbit 4-satellite monitoring system was proposed.Then，the space-based monitoring system's to solve the problems mentioned above was quantified and analyzed，and a cosrreponding model for evaluating the efficiency of the system was set up. A process for the implementation of the corresponding evaluation software was given and an integration of the scoring of various elements was completed in accordance with the visible and infrared spectrum. By analyzing and evaluating，the efficiency of the distant retrograde orbit monitoring layout in compensating for the full-time visibility of the invisible zone of the ground-based monitoring system was verified，as well as the enhancement of the capability of target discovery and cataloguing. This research could provide design reference for subsequent construction of space-based monitoring system.

TheThe process of an asteroid impacting the land is a complex non-linear dynamic process，which is difficult to study by using model tests. Numerical simulation provides an important tool for the analysis of this process. In this study，the large-scale numerical simulation of the dynamic process of the asteroid impacting land was realized initially by using the self-developed software CoSim-DEM based on the discrete element method (DEM). Based on the numerical simulation results，the four stages of the impact process—initial contact，impact excavation, high-speed ejection and adjustment—were simulated；the incidence angle and the dynamic behaviors of the asteroid during the impact process would affect the topographic characteristics of the crater. This study also indicates that large-scale numerical methods can be used to perform the analysis of dynamic process of the asteroid impacting the earth, and provide support for asteroid defense.

Based on the existing tracking and measuring conditions of China’s deep space exploration missions, the orbit determination accuracy of the DRO probe was simulated and analyzed. For the Cislunar space DRO exploration, the simulation adopted batch processing orbit determination method, selected celestial bodies centered on the Earth for orbit integration, and increased non-spherical gravitational perturbation of the moon. Under the current measurement conditions, the position and velocity accuracy of 2-day short-arc orbit determination using only range tracking data were the order of km and better than 3 cm/s respectively; for 7-day predictions, the maximum differences in the position and velocity are the order of ten kilometers and 6 cm/s respectively. When using ranging data combined with VLBI data, the position and velocity accuracy were the order of hundreds of meters and less than 0.4 cm/s respectively; for 7-day predictions, the maximum differences in the position and velocity were the order of kilometers and 2 cm/s respectively, which shows that VLBI data significantly improved the accuracy of short-arc orbit determination and prediction. Moreover, the position and velocity accuracy were better than 1 km and 1cm/s respectively when using 5-day long-arc range tracking data. For 7-day predictions, the maximum differences in the position and velocity were less than 2 km and 1cm/s respectively. This shows that an increase of ranging data significantly contributes to the accuracy of orbit determination and prediction for DRO.

This article proposed a 3D real scene modeling method for lava tubes that integrates airborne LiDAR, close-range photogrammetry, and point cloud data from GeoSLAM handheld laser scanner, with a focus on future lunar surface scientific explorations. Firstly, the entities were divided, and then entity feature extraction was performed based on semantic information. A new mesh model construction method was proposed, which uses multi-level model construction method and skeleton-plus-detail modeling method to construct the mesh model of the inner surface of the lava tube. Finally, entities were constructed separately between different layers inside the model to simulate the original state of different layers, and to measure layer thickness and volume of spallation. The 3D modeling of the lava tube located in Jingpo Lake, Heilongjiang province, shows that the 3D modeling method for lava tubes based on multi-source data fusion has high precision and high realism, providing an important reference for subsequent lunar lava tube skylight detection, Earth-Moon simulation comparison and internal exploration.

As for China’s first near-Earth asteroid defense on-orbit verification mission，the defensive disposal of the potential risk of near-Earth asteroid impact on the Earth was verified. The scientific objectives，scientific exploration mission were put forward，the scientific payload requirements analysis was conducted，scientific payload configuration was proposed. This study may provide a basis for decision-making for the implementation of the future asteroid defense missions .

Based on the Space Debris Experiment Telescope of the National Astronomical Observatories of the Chinese Academy of Sciences，together with the Yangwang-1 and Jilin-1 satellites，a space-based and ground-based collaborative monitoring experiment for near-Earth asteroids was designed and carried out. By using image processing and orbit determination methods，target detection and astronomical positioning of observation images were realized，and the orbit of near-Earth asteroids was precisely determined. Based on the analysis，the existing equipment can realize space-ground collaborative monitoring and orbit cataloging of near-Earth asteroids，and provide orbital data support for the study and estimating of impact risk of near-Earth asteroids.

To meet the demand for long-life carbon nanotube field emission cathode in deep space exploration，the failure mechanism of CNTs cathode was investigated，and a long-life CNTs cathode design was introduced. Patterning the CNTs as an array of CNTs island offers a way to eliminate the shielding effects of electrical field. In this way the areas of emitting CNTs are larger，which avoids over-heating on a small emission area. A bonding technique was introduced，the contact between CNTs and substrate was maintained by molecular forces previously，melting metal was introduced as the bonding layer. The mechanical robustness of the CNTs cathode was enhanced while the electrical/thermal resistance was reduced. Performance tests were conducted on the prototype in a high vacuum environment. The prototype produced a current of 0–1 mA with a resolution less than 2 μA and the noise level was less than 1 μA/Hz^1/2@0.01–1 Hz. The prototype was tested by over 550 hours' continuous emitting，showing good stability in long-term use.

Given the complex and numerous morphological features during asteroid landing，which lead to challenges such as huge number of feature combinations，high computational load in online feature selection and low computational efficiency，in this paper an online multi-type feature rapid selection method was proposed. Using rapid selection criteria for multi-type features combined with search region，a method for selecting single-frame image features was established. Additionally，considering the short sampling interval，high inter-frame image overlap，and high feature inheritance probability during asteroid landing，a method for inter-frame image feature inheritance selection was proposed. Simulation experiments show that the design of single-frame image search regions and inter-frame image feature inheritance methods substantially reduces the number of feature combinations，thereby greatly enhancing the efficiency of computational and online feature selection.

With the development of high-precision space exploration missions such as gravitational wave detection and Earth gravity field detection，the accuracy requirements of propulsion systems are further improved，and it is urgent to develop neutralizers with stable output of small current. In this paper，the working stability and electron extraction of carbon nanotube field emission neutralizer were experimentally studied. The current fluctuation characteristics before and after aging were tested， and spearman rank correlation test was used to analyze the correlation between background electric field and current fluctuation. Besides，three kinds of gate with different aperture were used to test the extraction characteristics of the neutralizer，and the influence mechanism of gate aperture on the performance of the neutralizer was analyzed. The experimental results show that aging treatment is helpful to improve the working stability of the neutralizer，and the background electric field of the emitter has a strong correlation with the instability of the emission current. The gate aperture has influence on both emission and extraction performance，and the 1 mm gate aperture has the best performance under experimental conditions. The results can provide some guidance for neutralizer configuration and structure design in propulsion system.

Aiming at the localization of lunar lava tubes, the volcanic lava cave in Haikou City, Hainan Province, was selected as the experimental area for simulated lunar lava. Localization methods including stereo vision-based method, laser scanning point cloud based method, vision fused IMU based method, laser point cloud fused IMU based method, and vision, laser point cloud and IMU fused method are applied to localization in the field areas of simulated lava tubes. The experimental results show that the accuracy of stereo vision could reach 3.59% in long-distance travelling mode, but the accuracy and robustness decreased significantly in harsh lighting conditions. Lidar could achieve a similar-level accuracy as vision-based method, reaching 1.89% in local area, but its robustness was affected by data acquisition rate and field of view. The integrated localization method using stereo vision, LiDAR, and IMU achieved robust localization results in lava tube areas with extremely harsh lighting and terrain undulations, making it the preferred choice for long-distance continuous localization. The research conclusions provide valuable reference for subsequent research on sensor configuration and localization methods for lunar lava exploration missions.

This paper reviews the recent research on the Kuiper Belt dust dynamics. Specifically, we review the related space exploration missions, introduce the origin and destruction mechanism of the Kuiper Belt dust, summarize previous studies on the modeling of the Kuiper Belt dust dynamics, and discuss the population migration mechanism as well as the contribution of Kuiper Belt dust to interplanetary dust in the inner solar system. This study helps to understand the dust environment in the solar system boundary and the interstellar space, and provide valuable insights for the orbital design of solar system boundary missions from the perspective of space environmental safety.

To meet the requirements for autonomy，rapidity，and adaptability in the collaborative planning of each subsystem during the attachment mission of a deep space probe，a collaborative planning strategy based on proximal policy optimization method and multi-agent reinforcement learning was proposed. By combining the single-agent proximal policy optimization algorithm with the hybrid collaborative mechanism of multi-agent，a multi-agent autonomous task planning model was designed. The noise-regularized advantage value ws introduced to solve the problem of overfitting in the collaborative strategy of multi-agent centralized training. Simulation results show that the multi-agent reinforcement learning collaborative autonomous task planning method can intelligently optimize the collaboration strategy of small celestial body attachment missions according to real-time environmental changes，and compared with the previous algorithm，it improves the success rate of task planning and quality of planning solutions，and shortens the time of task planning.

In this paper, a helical groove conical composite horn structure with multi-point drive rotation was proposed. A high-performance ultrasonic driller suitable for drilling in the inner wall of lava tubes was developed. An equivalent impedance network model was used to model and analyze the ultrasonic driller to predict the response characteristics of ultrasonic driller. The possibility of this drilling probe in applying complex ground conditions of lava tubes was verified through low gravity multi-angle simulated drilling tests and data analysis. The results show that the drilling rate increases with the increase of the hole’s opening angle for a drill rod diameter of 3 mm and a drilling pressure of 10 N. The maximum unloaded rotary speed of the driller is 506 rad/min，the drilling rate is 6.4 mm/min for vertical drilling，and the rotary speed while drilling is 259 rad/min.

To meet the robust landing requirement in the exploration and exploitation of small celestial bodies，based on the landing exploration missions in China and abroad，the requirements of intelligent landing technologies were analyzed and the corresponding research progress was discussed. Firstly，the landing exploration missions for small celestial bodies were reviewed. Then，the traditional rigid landing mode and the novel intelligent flexible landing concept of small celestial bodies were introduced，and the intelligent technology requirements of small celestial body landing were sorted out. On this basis，the research progress on intelligent landing technologies was summarized from the aspects of dynamics，mission planning，perception，navigation，guidance and control. Finally，the development trend of landing technology of small celestial bodies is envisioned.

In light of the demands for a micro-Newtonian level field emission electric thruster with wide，stable，precise， rapid，and persistent characteristics due to the drag-free control on satellites in space gravity wave detection missions，the mutual limitations between adjustable width range，resolution，and thrust noise should be broken through.Based on the principle of field emission thrust generation，and high-precision single pendulum to calibrate the accuracy of the model was uesd. Based on this thrust model，a flow and voltage-based active regulation strategy was established to control thrust，and a thrust feedback control strategy was proposed to maintain low thrust noise levels in a wider thrust range，accroding to the requirements for thrust control resolution and response speed. Finally，performance characterization was carried out on the developed prototype of the thruster principle，achieving 0.86-83.54 μN level，thrust resolution less than 0.1 μN，<0.1 μN/Hz^1/2，thrust noise in the millihertz frequency band less than 0.1 μN and less than 10 ms for thrust response time with constant flow.

Based on the issues closely related to the laser driving effect and the characteristics of asteroid materials, experimental research was conducted on the ablation driving efficiency of pulsed laser on near Earth asteroid materials. Different materials and porosity of asteroid like test samples were selected to measure the impulse coupling law. The experimental results show that under the action of pulsed laser ablation, C-type asteroids have higher impulse coupling efficiency than S-type asteroids; As the porosity of asteroids increases, the efficiency of impulse coupling decreases, and the efficiency of laser ablation driving decreases. In addition, experiments were conducted on the changes in mass of laser ablated asteroid like materials, and the results showed the existence of a laser power density that maximizes the efficiency of asteroid mass ablation. For threat asteroids that require long-term warning time, reducing their mass at the fastest rate while ablating and deflecting their orbits can further improve defense efficiency and achieve defense objectives.

Lava tunnels widely exist on planets and satellites, which can provide natural shelter for humans to land on in the future. Research on lava tunnels is of great significance. However, there are many challenges in extraterrestrial lava tunnel detection. Existing terrestrial lava tunnel detection schemes have devices that are not portable, with low levels of automation and work efficiency, and cannot be directly applied to the detection of extraterrestrial lava tunnels. To address the above problems, this paper proposes a 3D detection method for extraterrestrial lava tunnels based on the lightweight mobile measurement system, achieving efficient and detailed mapping as well as 3D morphology of lava tunnels, and carries out the verification in Earth lava tunnels. First, laser scanning is used to obtain the point cloud in the lava tunnel efficiently, and the 3D point cloud map of the tunnel is generated based on the iterative Kalman filtering algorithm. Subsequently, through point cloud processing methods such as ground filtering, tunnel wall extraction, and normal vector estimation, the 3D reconstruction of lava tunnels is achieved, followed by morphological analysis. This paper selects the Xianren Cave and Qishier Cave in Haikou, Hainan Province, as simulation scenarios for extraterrestrial lava tunnels to conduct experiments. Experiments indicate that the proposed method realizes real-time autonomous 3D mapping of lava tunnels. The generated point cloud maps and 3D models are more accurate and contain more detailed terrain information compared to existing research results. These indicate the proposed method better meets the morphological analysis needs of lava tunnels and provides a foundation for the in-depth study of extraterrestrial lava tunnels.

Flexible landing is a new way to prevent rebound and overturning in weak gravity environments of small celestial bodies and improve landing safety on these bodies. To realize obstacle avoidance of the flexible lander during the landing process，an adaptive curvature guidance method combined with convex programming and the concept of virtual safety boundary was proposed. Based on the geometric convex trajectory obtained through curvature guidance，a virtual safety boundary related to the structural characteristics of the flexible lander was constructed. The shape of the boundary was adaptively adjusted according to terrain obstacle information，and the optimal obstacle avoidance trajectory was solved via successive convex programming technique. The result of numerical simulation shows that the method proposed in this paper possesses satisfactory obstacle avoidance capability for the flexible landing mission in complex terrain conditions，which further improves the landing safety on small celestial bodies.

In order to solve the problem of attitude maneuvering control and attitude planning for the flexible probe under multiple constraints in the asteroid flexible attachment scenario，in this paper, a goal-oriented attitude planning method for an asteroid-attached flexible probe was proposed. By constructing a node-plane coupling dynamic model, the attitude description and dynamic constraint characterization of the flexible three-node probe were realized. A local optimization expansion strategy was designed to improve the RRT algorithm. The optimization objective was to shorten the distance to the target attitude. The quadratic programming problem was constructed by combining with the attitude dynamics model of the flexible body to enhance the purpose of maneuvering along the attitude path. The simulation results show that compared with the traditional heuristic planning method, the proposed method takes less time to calculate, optimizes the attitude maneuver path length, and can meet the attitude maneuver requirements during the flexible landing process of the asteroid probe. It provides support for the implementation of the small body project.

A method for attitude-orbit coupling intelligent control of flexible lander based on maximum entropy reinforcement learning is proposed in this paper，aiming at solve the adverse effects of the complex perturbation environment and the inaccurate flexible deformation force. Firstly，the orbital dynamics model of the equivalent agent is established by introducing the internal flexible force of the lander. The datum plane method is used to characterize the attitude of the flexible lander with complex deformation. The attitude-orbit coupling dynamic environment of the lander is constructed to train the intelligent controller. Then，an intelligent controller with deep neural network architecture is designed according to the soft actor-critic（SAC）algorithm of maximum entropy reinforcement learning theory. Each thruster can keep the lander attitude stable and track the navigation trajectory with high precision by self-adapting the output thrust. Finally，the landing process with the controller deployed is simulated. The simulation results show that compared with the classic PD control method，the intelligent control method proposed in this paper has stronger robustness.

In the process of small body attachment detection，due to the limitation of computational resources，it is difficult for the sequence image autonomous relative navigation system to process a large amount of optical image information. In this paper，a relative navigation observation sequence planning method is proposed，and an observable measurement index describing the observation accuracy of the landmark is established based on the Fisher information matrix，which is used as an index to design the observation strategy for the preferred selection of the key observation moments. In order to verify the validity of the relative navigation method，a small body attachment experiment platform is constructed，and the 6-degree-of-freedom attachment motion simulation of the lander is realized by pulling the load platform with 8 ropes in parallel. Finally，a visible light camera is mounted on the experimental platform to realize the semi-physical simulation of the relative navigation of small body attachment，which greatly reduces the computational burden of the navigation system while providing high-precision relative navigation. It will provide reference for the asteorid project in the future.

In view of the disturbance of the frequent Wheel Off-Loading(WOL) of Tianwen-1, firstly, this paper analysed the perturbation magnitude of WOL and the effect on the orbit in its relay and remote sensing orbits. Secondly, a uniform acceleration model in RTN coordinate system was established to describe the acceleration produced by WOL events, several strategies were proposed to analyze the orbit of the relay and remote sensing orbit respectively, and finally orbital accuracy was assessed by overlap comparison. The results show that WOL events are the main error, affecting orbital accuracy. The position accuracy of the relay orbit is about 150 m, and in the remote sensing orbit where the unloading events are more frequent, the position accuracy decreases to 700 m.