Based on the situations where ground stations can’t directly measure hunar far-side or polar regions， and where current tracking and control systems face limitations in improving telemetry rates and measurement accuracy dueto the Earth-Moon distance，the Queqiao-2 relay satellite’s TT&C system is designed to achieve a four-way measurement chain-Earth-satellite-probe-satellite-Earth-enabling real-time tracking and measurement of lunar spacecraft that are not directly visible from Earth. Additionally this system serves to validate a GMSK+PN-based tracking and control communication scheme. Since the in-orbit launch of the Queqiao-2 relay satellite，the TT&C syatem has consistently and stably perfomed TT&C tasks. Simulation results of the four-way meaurement demonstrate that it can achieve meter-level positioning accuracy for the lander. Calculation of the new TT&C scheme indicates that it can achieve centineter-level ranging accuracy at the Earth-Moon distance. The actual operational perfomance and simulation verification results demonstrate that the Queqiao-2 relay satellite’s TT&C system design meets the mission requirements and can provide reference for the design of TT&C systems for future deep space exploration and lunar exploration missions.

As To meet the requirements of the Queqiao-2 relay communication payload for multiple deep-space exploration missions and relay communication services，a design method for comprehensive data processing and transmission with high performance，high integration, and high reliability was proposed. he research and development of key technologies such as front-end multi-source data scheduling and management，on-board reconfiguration and minimal system design，and wear leveling of large-capacity solid-state storage have been mainly completed. Through ground testing and on-orbit verification，this system has realized relay communication services between multiple lunar mission spacecraft and ground stations，as well as deep space exploration storage-computing-control integrated technology exceeding 8 Gb/s. It supports software on-orbit reconfiguration，and for the first time achieves a downlink data rate to Earth covering the range of 1–500 Mb/s. Moreover，it effectively supported the successful implementation of the world's first sampling return mission from the far side of the Moon—China's Chang'e-6 mission. This work can provide a reference for data processing and transmission design in future deep space exploration missions.

Aiming at the problem that the regenerative forwarding delay of relay satellites is difficult to directly simulate the real on-orbit link on the ground，a ground test method for measuring the relay forwarding delay of Queqiao-2 was proposed. By constructing an equivalent satellite-ground transmission channel，the method enabled precise measurement of the regenerative forwarding delay. A closed-loop calibration procedure was incorporated into the test system to eliminate the effects of equipment delay and transmission path delay. This approach effectively overcomes limitations of existing methods，such as significant errors in segmented testing，stringent requirements for high-precision time synchronization，the need for extensive test equipment，and difficulties in simulating true environments.Verified through ground tests and on-orbit validation，the method is operationally simple and offers high delay measurement accuracy. It provides strong support for evaluating and optimizing the Queqiao-2 communication system and serves as a valuable reference for measuring telecommand transmission delays in other satellites，demonstrating significant engineering value.

Queqiao-2 faces key challenges including long-duration Earth shadow，intense radiation，extreme temperature fluctuations，antenna shading，weight constraints，and multi-payload safety. A highly reliable and intelligent power supply and distribution scheme was proposed. A Fully Regulated Bus（FRB）topology was adopted to achieve efficient and stable energy supply，an intelligent power distribution and hierarchical protection architecture was constructed to enhance bus safety and disturbance rejection capability；a redundant fault-tolerant control circuit for pyrotechnic devices was designed to ensure reliable execution of critical actions，and an autonomous battery life-cycle management strategy was established to achieve long-life on-orbit operation. Ground simulation and test verification，along with in-orbit operation data，indicate that indicators such as system power supply capability and battery depth of discharge meet the design requirements，and the operation is stable and reliable. This research can provide an important technical reference for the design of power supply and distribution systems for deep-space exploration spacecraft.

In response to the communication blind spot issues between the far side of the Moon and Earth faced by the fourth phase of the lunar exploration project，Queqiao-2 satellite operated in a large elliptical frozen mission orbit around the Moon，and provided a stable communication link for lunar far-side exploration missions，utilizing its onboard communication equipment，including an umbrella-shaped deployable parabolic antenna and a two-dimensional steerable parabolic antenna，to provide a stable communication link for lunar far-side exploration missions. To address the challenges of harsh external thermal flow environment and great difficulty in thermal control of cables and moving components，a design scheme with active-passive methods was proposed. By conducting an external heat flux environment analysis for the lunar distant elliptical frozen Sun-synchronous orbit，and combining the antenna’s operating mode and component states，a thermal control design scheme was determined. Thermal Desktop thermal analysis software was used to perform thermal simulation analysis on the antenna，and the results based on calculation guided the components to perform supplemental material-level low-temperature storage tests，and the results indicated that the temperatures of all antenna components met the specified requirements. After the successful launch，the antenna temperatures remained at a good level，particularly during the Chang’e-6 mission，where the relay satellite’s antenna successfully completed the communication task for the first human lunar dorsal sample relay communications mission. The research findings can serve as a reference for thermal design of antennas in deep-space exploration missions.

To address the issues of complex scientific payload operation modes，high individual requirements，and difficulties in lightweight design for Queqiao-2 relay satellite，a design method based on subsystem integration optimization was adopted. A scientific payload manager was configured to achieve tightly coupled integration，unified power supply and distribution，data processing，and interface management. Meanwhile，digital simulation verification and on-orbit calibration planning were carried out in parallel. Through simulations and ground verification tests，it has been demonstrated that this method effectively enhances system integration，reliability，and fault handling capabilities，meeting the mission requirements of up to eight years in orbit. The results show that the developed payload system solution，characterized by high integration，high reliability，and long-term operability，can provide an important reference for the design of payload systems for future Chinese lunar and deep space exploration missions.

A multi-maneuver approach to transition from Lunar Frozen Orbit (LFO) to a cislunar L2 Near Rectilinear Halo Orbit (NRHO) was developed in this research. LFO was utilized to provide the navigation or communication platform for lunar exploration. They are long-term stable orbits with constant orbital elements on average. Subsets of Halo orbit families, known as NRHO, are orbits that are nearly stable. Due to their important locations in cislunar space, the L2 NRHO are considered as possible launching platforms for deep space or lunar exploration mission. For upcoming cislunar space exploration missions, the low fuel consumption transfer approach between these orbits is very valuable. Utilizing the maximum stretching direction to determine the insertion maneuver, the spacecraft may rapidly approach NRHO. In order to optimize the transfer trajectories, a nonlinear programming problem was developed. The optimization results with different transfer windows in the high-fidelity model were given for the transfer from LFO to NRHO, demonstrating the reliability of the proposed strategy.

Existing lunar constellation designs consider communication and navigation functions separately，failing to effectively utilize integrated communication-navigation technologies to reduce the overall cost of constellation design. A novel method for designing lunar constellations based on recurrent orbit was proposed，utilizing a multi-objective optimization framework that concurrently evaluates coverage multiplicity，communication performance，and navigation accuracy constraints through a non-dominated sorting genetic algorithm. The optimization results show that，with 12 lunar recurrent satellites，an average Positioning Dilution of Precision (PDOP) of less than 7 across the entire lunar surface and full-time triple coverage in mid-to-high latitudes can be achieved. The proposed scheme can provide high-speed communication and high-precision positioning and navigation services that are both cost-effective and technologically advantageous for future lunar exploration activities，while demonstrating the potential of integrated communication-navigation technologies in reducing system costs.

To address the issue in traditional SINS/DVS integrated navigation methods that is required a spacecraft to simultaneously carry three sensors to observe three navigation stars for comprehensive velocity error correction，an inertial/time-segmented astronomical Doppler velocity integrated navigation method based on sensor maneuvering (SINS/TS-DVS) was proposed. By periodically changing the optical axis pointing through sensor maneuvering，DVS measurements in different directions were acquired. This method ensured navigation accuracy while reducing the burden on the spacecraft. Simulation results demonstrate that the position errors of the SINS/TS-DVS integrated navigation in longitude，latitude，and altitude directions were significantly improved compared to the traditional Strapdown Inertial Navigation System (SINS) and the SINS/DVS method observing only one star. It can effectively enhance spacecraft positioning accuracy.

To address the need for in-situ characterization of extraterrestrial regolith in deep space exploration，this study quantifies the correlation between high-frequency passive features in signals and particle size under low-velocity impact scenarios on planetary surfaces，such as landing，penetration，and sampling. The feasibility of utilizing these features for particle-scale identification is explored. A spherical impactor equipped with built-in accelerometers was designed，and impact experiments were conducted on Earth using dry sand with varying particle sizes and relative densities，providing calibration and validation data for the identification method. Time–frequency spectral analysis was performed on the acceleration signals. The rigid-body acceleration signal a_rigid(t) was used to normalize the original acceleration signal，yielding a dimensionless fluctuation signal a_fluc(t). Based on the power spectral density of a_fluc(t)，a fluctuation energy metric E was obtained，and a fluctuation energy coefficient χ was defined to quantify the degree of acceleration signal fluctuation. Using the experimental data，an empirical relationship between the ratio of the spherical impactor diameter D to the mean particle diameter $ \bar{d} $ and the fluctuation energy coefficient χ was established，and supplementary validation experiments were performed. The results show that the particle size d_g is the dominant granular medium parameter influencing the dimensionless fluctuation signal a_fluc(t)；the relative density Dr mainly affects the rigid-body acceleration a_rigid(t) and its peak value，but has little influence on a_fluc(t)；and when the diameter ratio between the impactor and the mean particle size is less than or equal to 30，the fluctuation energy coefficient χ exhibits good sensitivity for identifying the mean particle size $ \bar{d} $. The above results indicate that the fluctuation characteristics in the acceleration signal and their calibration relationships can serve as auxiliary diagnostic indicators for identifying the particle scale of extraterrestrial regolith，supporting the interpretation of acceleration data obtained during contact processes.