In response to the development trend of large-scale, complex, and intelligent space missions, this paper addressed the trajectory optimization challenges faced in space target cooperative exploration missions by reviewing the principal technological methods of spacecraft trajectory optimization. These methods include the current state of research and advancements in optimal control methods, intelligent optimization methods, and machine learning approaches. Based on this, the paper further explored trajectory optimization scenarios, mission design issues, and optimization characteristics represented by space debris removal, Earth observation satellites, small body exploration, and in-orbit servicing. Finally, the paper discussed the existing research challenges and anticipated the design requirements for trajectory optimization, aiming to provide new technological perspectives and solutions for future complex space missions.

This study focuses on the Pakistan ICUBE-Q CubeSat carried by the Chang’E-6 mission，systematically analyzing its orbital characteristics，dynamic environment，and measurement methods，with particular emphasis on the primary perturbative factors affecting its orbital variations. In the absence of range and Very Long Baseline Interferometry (VLBI) support，a three-way Doppler velocity measurement model was proposed for orbit determination，and the velocity measurement errors were thoroughly analyzed. Additionally，an orbit determination strategy suitable for sparse observation modes was designed，and error assessment was conducted. Furthermore，a detailed analysis of the long-term orbital evolution of the CubeSat was performed. The results indicate that the Root Mean Square (RMS) of the three-way Doppler velocity residuals was 2 mm/s，and the orbit determination accuracy achieved a position precision better than 1 km. The CubeSat’s orbit was primarily influenced by lunar non-spherical gravitational perturbations and Earth’s point-mass gravity，with three-body gravitational effects playing a significant role in its orbital evolution. Orbital evolution predictions reveal that the CubeSat’s perilune distance is expected to decrease to less than the lunar radius by April 2025. This study provides valuable insights into orbit determination and evolution analysis for microsatellites in deep space exploration missions.

The orbital dynamics of dust particles ejected from the surface of 162173 Ryugu and escaping into interplanetary space within 1 000 years, mean motion resonance of dust particles with Earth and close encounters between dust particles and Earth were analyzed using direct numerical simulations. The effects of non-gravitational perturbations (solar radiation pressure, Poynting-Robertson drag and solar wind drag) on the long-term orbital evolution of dust particles were investigated. In the spatial region where dust particles move, the evolution of the semi-major axis, eccentricity and orbital inclination of the dust particles in the 3:4 and 4:5 mean motion resonances with the Earth were analyzed. That is, the semi-major axis of the dust particles showed periodic oscillations, the eccentricity showed periodic changes and slightly increased, and the orbital inclination showed a periodic downward trend. The number of close encounters between dust particles and the Earth was counted and analyzed. It is found that the number of close encounters reaches a maximum value within a period of 400 to 500 years, and the dust particles will not collide with the Earth within 1 000 years.

A desensitized trajectory optimization method was proposed to improve the precision of small body landing control in complex environments, under the influence of the uncertainty of dynamic parameters and state during small body landing. Firstly, considering the influence of uncertain parameters, the augmented stochastic state equation of small body landing was established, and the uncertainty of the gravitational field of small body and the thrust error of probe engine were regarded as the process noise of landing process. Then, the linear covariance dynamic equation of uncertainty propagating along the nominal trajectory was derived, the covariance matrix of state variables was extended to a new state of the state equation, and the joint performance index weighted by fuel consumption and state covariance was constructed. Then the optimal control problem was solved by direct trajectory optimization method and the trajectory’s desensitization was finally improved. Taking 433Eros as an example, the simulation results show that the proposed method can overcome the influence of random parameters in the process of small body landing and improve landing accuracy.

The large number of variables for Venus-Mercury exploration trajectory design results in the difficulty to find the global optimum. Therefore, a segmented optimization method was proposed. Firstly, the Venus-Mercury transfer window was searched to reduce the cost for Venus capture and Mercury capture. Then, the Earth-Venus transfer trajectory with Venus gravity assists was optimized, and the launch window was obtained. Finally, the Venus/Mercury capture trajectory with successive Venus/Mercury gravity assists was optimized. Based on V∞-leveraging maneuver principle, an optimization index of leveraging maneuver efficiency was proposed. The trajectory after each gravity assist was optimized separately so that the velocity increment for Venus/Mercury capture was reduced steadily. The simulation results reveal that the velocity increment for the Earth-Venus transfer segment and the Venus-Mercury transfer segment could be zero when 2 Venus gravity assists were executed. The velocity increment for Venus capture could be reduced by 1.4 km/s when 2 or 3 Venus gravity assists and V∞-leveraging maneuvers were executed. The velocity increment for Mercury capture could be reduced by 2.3 km/s when 4 Mercury gravity assists and V∞-leveraging maneuvers were executed. Compared with trajectory optimization for Mercury exploration, the proposed method can reduce the overall velocity increment for Venus-Mercury exploration by constraining the V∞ for departing from Venus and arriving at Mercury.

The modeling and application of satellite to ground and Inter satellite link ranging was studied in this paper. Firstly, based on the measurement principle, the observation modeling method for one-way measurement was derived in detail under the reference frame in general relativity. Secondly, the method of clock error elimination and clock error estimation were given through the summation combination and difference combination. Thirdly, according to the characteristics of the summation combination observation model, the calculation formula for the difference between the proper time and the coordinate time was derived, and a specific algorithm implementation was provided. Finally, the influence of relativistic effects on one-way measurement modeling was analyzed using typical orbital examples. The results show that the difference between the Earth-Moon space position conversion caused by the relativistic effect is on the order of 10 meters, and the difference between the proper time and the coordinate time changes by tens of microseconds per day, which is a factor that must be considered in high-precision navigation modeling, and the modeling algorithm proposed in this paper can serve the application of high-precision navigation in cis-lunar space.

In order to understand the SAR imaging characteristics of the lunar surface and assist in the design of SAR imaging observation systems around the moon using existing data，a simulation scheme for lunar surface SAR images based on lunar topographic data is proposed. In this scheme，given the circumlunar trajectory and baseline parameters，the corresponding off-nadir angles are calculated based on the existing lunar Digital Elevation Model (DEM) data and the set SAR imaging parameters. The local incidence angles for each point on the lunar surface are then calculated，and the simulation is performed based on the RD model and interferometric height measurement principle，using the set backscattering coefficients. This process generates simulated SAR amplitude images and interferometric phases. The effectiveness of the simulation scheme was verified by simulating lunar surface SAR images under different baseline conditions using the LOLA DEM with a grid spacing of 118m.

The visible quantity and time of GNSS (Global Navigation Satellite System) satellite signal in lunar orbit is an important factor for lunar probe to use GNSS to realize auxiliary navigation. To deal with the problems that the number of GNSS satellites visible by lunar orbiting satellites and lunar surface detectors is not clear and the comparative analysis is insufficient, this paper selected the lunar elliptical frozen orbit (ELFO), the Peter region of the moon and the Shackleton region of the south pole of the moon as analysis targets, analyzed and statistically analyzed the number and duration of visible GNSS satellites under different ELFOs, lunar surface conditions, and lunar South Pole relay conditions. Simulation results reveal that, in the Peter region, minor surface movements have minimal impact on the number of signals received by Beidou satellites; and at Shackleton, the South Pole’s ELFO-Satellite 3 orbit supports visibility of up to four Beidou and GPS satellite signals during positioning activities. The ELFO-Satellite 3 orbit demonstrates the highest GNSS signal reception within its operational cycle, offering substantial potential for lunar navigation. These findings provide valuable insights for China’s “Magpie Bridge” Navigation Remote Constellation System and future lunar probes, especially in leveraging GNSS satellite signals for navigation and positioning on the lunar surface and in lunar South Pole regions.

Recognition and classification of Mars analog terrain aim to simulate and study the Mars environment by analyzing Mars analog terrain images，which holds significant research value for exploring scientific questions such as formation，evolution，and potential habitability of Mars. In response to the challenge of balancing classification performance and model lightweighting in current Mars terrain classification algorithms，a lightweight，rapid recognition and classification method for Mars analog terrain is proposed (LWNet). This algorithm constructs a dual-branch teacher-student network，employs knowledge distillation to reduce the number of parameters and computational load of the model，and integrates attention mechanism to enhance the capability of terrain classification and recognition，achieving high accuracy and lightweight classification models. To verify the classification performance of the proposed method，a dataset of Mars analog terrain on Earth was established，including four typical Mars landforms: cliff，desert，channel，and yardang，with each type of terrain consisting of 800 images. The dataset was employed to conduct rapid recognition and classification experiments with LWNet. The results indicate the overall accuracy reaches 97.81%，which only decreases by 1.25% compared with Swin-Transformer，while its Parameters and FLOPs are only 1.3% and 4.8% of Swin-Transformer，respectively. Experimental results verify the effectiveness and superiority of the LWNet.

Search for life on Mars requires an understanding of the evolution history of Mars geological environment and its impact on the formation and preservation of life. In this paper, the latest research achievements in the history of Mars geological evolution were summarized, the history and progress of life exploration on Mars were reviewed, and shows that there was once a large amount of liquid water activity on the surface of Mars, groundwater and hot spring activities are also present. There are a variety of hydrogenic landforms and minerals, with the necessary elements to form life. The search for traces of life on Mars should focus on areas of long-term water activity, including ancient oceans, lakes, deltas, groundwater and hydrothermal activity regions, as well as cave interiors that could provide habitable environments. The present Martian environment is very harsh for the formation and preservation of life . The surface of Mars is subjected to intense radiation and the future exploration of life on Mars should pay attention to the deep sedimentary strata and caves. The microbial population on Mars may be scarce; collecting samples from right sites and bringing them to Earth and using the-state-of-art technology on Earth to search for possible traces of life on Mars is the best option.