The Chang′e-6 lunar probe is designed to achieve the first robotic sampling and return mission from the far side of the Moon.Lunar far side is overall of rugged terrain and is lack of flat area for sampling on the surface.Two areas in Apollo basin within south pole Atiken basin （SPA）are selected as primary and backup targeted landing sites，the safety and reliability of landing，lift-off and surface operation process are ensured.In order to achieve new mission objectives based on fundamentally determined technical status，an optimal system design solution is put forward to reduce system changes.The risks associated with alterations of technical status are avoided.Through comparative analysis，a retrograde orbit around the Moon is determined，ensuring minimal system modifications and optimal system design.In consideration of the reduced and discontinuous duration of relay telemetry and control on the far side of the Moon for Chang′e-6，a phased，highly autonomous，and cooperative relay-assisted lunar surface operation timeline design is proposed to ensure the implementation during landing，lift-off and surface operation process.For payload carried by Chang′e-6，a system design is proposed by using data processing units as the central exchange hub to ensure electrical interface safety isolation；customized detection modes are also developed for different payloads to maximize detection benefits without affecting the completion of the main mission.These methods are applied in the Chang′e-6 mission，ensuring the success of the world′s first robotic sampling and return mission from the far side of the Moon，valuable reference and experience are provided for follow-up lunar exploration and deep space exploration missions.

During the lunar orbit flight phase of the Chang′e-6 lander and ascender module (LAM), the 10N thruster (could be used in a force-couple method) on the ascender and the 150N thruster on the lander are implemented for the attitude control. However, there exists some fault cases when one 10N thruster failed to fire and the other pair one could work well, the propulsion system could generate opposite control torque due to the installation of thrusters and the attitude could be instable accordingly. To ensure the attitude stability in the 10N thruster fault case, a dual-loop fault tolerant attitude control is proposed with a 10N thruster in the inner loop and a 150N thruster in the outer loop. Numerical simulations illustrate that the LAM attitude in the lunar orbit could still meet the requirements even in the case of the 10N thruster fault. Therefore, the proposed dual-loop attitude control, which implements coupled attitude control thrusters and redundant thrusters, could effectively manage the coupled thruster fault and ensure the stabitlity.

In order to provide relay communication supports for future Chinese lunar exploration program，Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2，including mission orbit and transfer orbit design，configuration and layout design，housekeeping and information flow design，power supply and distribution design，GNC and propulsion system design，communication links design，etc.，was accomplished through comprehensive tradeoff and evaluation on technical maturity，availability，schedule，cost，and so on.With a view to reducing development risk，both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies，modulations，data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20，2024，by means of 5 orbit maneuvers，Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations，Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions，as well as the capacity to perform scientific observations.Under the support of Queqiao-2，Chang′e-6 achieved its ambitious mission goal to collect  and return samples from the moon′s mysterious far side.In the meanwhile，Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design，it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition，innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture，multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching，orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2，more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.

Space radioisotope power is a space power device that converts nuclear decay thermal energy into electrical energy through thermoelectric conversion technology，and is widely used in deep space exploration missions.Space isotope power commonly uses plutonium 238 as nuclear sources.The preparation and production of plutonium 238 are difficult and expensive，resulting in worldwide limited production capacity.Meanwhile，long-term deep space exploration missions propose high requirements for the lifespan of isotopic power.Space thermal photovoltaic radioisotope power with high thermoelectric conversion efficiency and long lifespan has become the preferred technical route for deep space exploration missions.NASA has demonstrated a RTPV prototype with a conversion efficiency greater than 20%.In recent years，near-field thermal photovoltaic and spectral-regulation thermal photovoltaic technology have become the hotspot.Significant progress has also been made in the theoretical research and technical verification of critical devices such as emitters，optical filters，and photovoltaic cells.In this paper，the research progress of RTPV system designs and relevant key devices is reviewed.Based on the system level requirements，the development status of each device is stuaied and the future trend is suggested.This paper provides a reference for promoting the engineering development of thermophotovoltaic radioisotope power supply system in the future.

With the development of aerospace technology，the functional integration of spacecraft has been improved，and the complexity of research and development has increasingly high requirements for system heat dissipation.As a two-phase high-efficiency heat transfer component，loop heat pipes（LHPs）have the characteristics of long distance，anti-gravity，and flexible layout，which are often used for directional heat transfer under a single heat source.For complex environments with multiple heat sources，LHP systems have poor stability，which are generally difficult to adapt to.A strong coupling heat management system for LHPs based on brazing technology is designed to meet the heat dissipation requirements of dispersed heat sources under complex spatial heat flux.Sensitivity analysis of key coupling parameters is conducted，and relevant experiments are conducted to verify the feasibility of key technologies such as low thermal resistance and strong coupling at the interface.The platform's heat dissipation capacity is improved by 52%.LHPs，having been applied to payload module of the Land Exploration Satellite-4（LEX-4），which is the first large-scale application in the platform system in the world，improve heat dissipation capacity of the payload module from 4kW to 6kW，providing an on-orbit temperature environment of 0 - 20℃ for the high-power solid-state amplifier.LHP breaks through the restriction of platform application，which provides reference for the design of thermal coupling systems for LHP in the future.

Enhanced microchannel flow boiling heat transfer using nanofluids is an effective method to improve the heat transfer performance of high-power electronic devices.However，conventional nanofluids face the challenges of complex fabrication processes，poor stability，and the inability to control nanoparticle size，which negatively affect the overall heat transfer efficiency.A simple microfluidic synthesis strategy is developed to prepare highly stable and size-controlled silica nanofluids in a continuous，efficient and high-throughput manner.A specially designed helical microchannel reactor enables continuous flow one-step synthesis of stable nanofluids with controllable particle sizes ranging from 30nm to 110nm simply by flow rate adjustment.The results of flow-boiling heat transfer experiments show that at higher flow rates（0.4m/s），the heat transfer performance of smaller-sized nanoparticles（≤55nm） is better than that of larger-sized nanoparticles（110nm），and the enhancement for critical heat flux（CHF） and heat transfer coefficient（HTC） reaches 90.9% and 68% respectively.The enhanced wettability of the boiling surface，efficient surface nucleation，and improved bubble dynamics provide theoretical explanations for the enhanced heat transfer performance.These findings provide not only a new method for controllable preparation of nanofluids，but also new ideas for efficient two-phase chip cooling of power devices in aerospace and power electronics.

 The sensing delay of orbit change in turn-based orbit pursuitevasion game brings difficulties to differential game approaches，and deep reinforcement learning-based algorithms are still risky for engineering applications due to the inexplicability.The predictive-value-accumulate Monte Carlo tree search（PVA-MCTS） algorithm is proposed for the turn-based orbit pursuit-evasion game.Based on the predictability of spacecraft orbital motion，the algorithm predicts and accumulates the decision value in the game.This solves the problem of sparse reward and large time span in the turn-based orbit pursuit-evasion game，and improves the learning efficiency.It is used to solve the turn-based orbit pursuit-evasion game，and compared with the results obtained by Monte Carlo tree search（MCTS） algorithm.The results show that the PVA-MCTS algorithm reduces the pursuit time by about 27.6% and increases the escape time by about 6.8% for pursuer and evader respectively.The PVA-MCTS algorithm is realistic for the application of orbital game in the fields of non-cooperative target approaching and collision avoidance.

It is a typical scenario of orbit game that several low-cost spacecraft cooperate to capture highly valuable non-cooperative targets.In the consideration of autonomous maneuver of the target，the key problem unsolved is how to quickly design the capture configuration to achieve on-orbit capture reliably and efficiently.A design method of the spacecraft cluster capture configuration based on reachable domain（RD）is proposed.Firstly，the dynamic model of capture mission is established，and the conditions of the capture mission with cluster are described.Then，a criterion for multi spacecraft to capture non-cooperative targets is proposed based on the RD method for continuous thrust maneuver.Furthermore，the optimal control theory is used to solve the RD of spacecraft，the characteristics of the RD are analyzed，and then the semi-analytical solution of collaborative RD of the spacecraft cluster is proposed.Finally，a design method for collaborative capture configuration using four spacecraft is proposed.In this paper，the simulation results verify the full effectiveness of the cluster capture configuration design method；and compared with the traditional single spacecraft continuous thrust RD solution method，the feasibility of the method for solving the RD is proved.

The forecasting and the location of long-lifetime orbits in close proximity of small celestial bodies are important concerns of orbital design for the near-small-body stage due to the weak gravity and considerable uncertainty of the physical characteristics and orbital dynamics.For the complex dynamical environment near irregular small celestial bodies，gravitational perturbations of J2，J3，J4 terms，solar radiation pressure（SRP）and eclipses are taken into account.A semi-analytical approach that can rapidly determine the type and existence region（range of initial orbital elements）of long-lifetime natural orbits around asteroids is developed based on averaged dynamics.An analysis is also conducted to assess the impact of factors，such as SRP，eclipses，and variations of the asteroid-probe system parameters，on the existence regions of these orbits.During the search for natural orbits around the potentially hazardous asteroid 99942 Apophis，two families of long-lifetime orbits are discovered.The first family consists of heliotropic orbits，which have a smaller existence region and are more sensitive to parameter uncertainties.The second family comprises terminator orbits，which exhibit a larger range of semi-major axes and demonstrate greater stability.The research indicates that SRP has a significant impact on the existence of long-lifetime orbits around irregular small celestial bodies.When considering the effects of SRP，the existence regions of these orbits are notably reduced.As the SRP strength becomes stronger，the heliotropic orbits tend to have higher eccentricities，while the terminator orbits have lower eccentricities，and the range of semi-major axes becomes smaller for both orbit families.

An orbiting sample capture and orientation system architecture for the orbiting sample capture retrieve system concept is developed to enable on-orbit capture，orientation，and transfer of a Mars sample container into a containment vessel as part of a potential Mars sample return（MSR） campaign.The concept uses a rotating trap cover for orbiting sample （OS） capture，and four sector devices to form a retractable capture space for constraining and fixing OS container.The conveyor belts on the sector devices drive cooperatively with each other to realize OS container attitude return and to transfer to a containment vessel with friction force and protruding bars acting on the OS container.In order to accurately realize sample orientation and transfer，a coordinated action strategy between the sector devices and the conveyor belts is formulated based on the sector angle signals.A prototype of OS capture and orientation mechanism is designed and developed，and the functions of OS capture，orientation and transfer are tested and verified.The mechanism has the characteristics of light weight（<12kg），high integration of orientation and transfer functions，strong adaptability of OS container attitude correction，and high transfer reliability，and can be applied to potential Mars sample return mission.

With increasing demand for high resolution，integration and agility of optical remote sensing small satellites，visible/infrared dual-color common aperture camera as well as CMG（control moment gyroscope） are installed to meet the requirements of miniaturization，all-day and night，multi-target and multi-model imaging.On such satellites there are several kinds of components with micro-vibration，including CMG，infrared camera cryocooler，etc.，which has a great influence on image quality of camera and is difficult to suppress.Therefore，a comprehensive method for suppressing microvibration caused by above-mentioned disturbance sources is proposed，including CMG vibration isolator，isolating installation between cryocooler and camera optical structure，and damping truss is designed and installed to realize isolation between camera optical and satellite platform structure.Using above integrated disturbance source damping and terminal isolation measures，through analysis，calculation，satellite micro-vibration experiment verification and in-orbit test，the effect of micro vibration on image quality can be effectively reduced.Even for visible infrared integrated camera，the in-orbit dynamic MTF（modulation transfer function）of visible channel with sub-meter resolution can reach 0.1，and the influence factor of micro vibration on MTF can be controlled at 0.991.

 The unscented Kalman filter （UKF）of GNSS/SINS integrated navigation system is based on the accurate statistical characteristics of measurement noise.When the statistical characteristics of measurement noise change，the filtering performance of UKF will decrease or even diverge if it is not accurately estimated.To solve the above problems，an adaptive UKF algorithm based on improved Sage-Husa （ISHUKF）for GNSS/SINS integrated navigation system is proposed.Firstly，the simplified UKF model of GNSS/SINS nonlinear integrated navigation system is established.Then，an improved Sage-Husa algorithm is proposed based on the analysis of the filter divergence in the conventional Sage-Husa algorithm to ensure the positive quality of the estimation variance of measurement noise.Finally，the simulation experiment of GNSS/SINS integrated navigation system is carried out.The experimental results show that,compared with the Variational Bayesian algorithm，the ISHUKF has roughly the same estimation accuracy for the measurement noise variance，and the algorithm is simpler.Compared with the standard UKF algorithm，the position accuracy，velocity accuracy and attitude accuracy of the integrated navigation system can be improved respectively by about 33%，35% and 72% during the whole simulation period，which verifies the feasibility and superiority of the ISHUKF algorithm and also provides a simple filtering method for integrated navigation system in complex environment.

Satellite video stabilization is the prerequisite and basis for realizing high-precision satellite video applications.Due to the insufficient accuracy of satellite pointing attitude and the insufficient stability of platform attitude，image alignment technology is usually implemented to achieve the video gaze effect; however，when observing the sea targets，there is no control point calibration and feature point-based alignment cannot be carried out between frames，the staring video camera has the problem of repeated jumping of the targets on the image plane during observation.In this paper，a global foreground video stabilization （GFVS）method is proposed based on multi-target ship detection at sea.A Gaussian error model is constructed，and the image plane is corrected with the deviation between the optimized position and the original position，and finally the stabilized video is synthesized.The experimental results show that the method in this paper can effectively solve the problem of difficult alignment of dithered images when the control points at sea are insufficient，and get more stable video effects，the error of the stabilization can be controlled within 0.9 pixels by applying two datasets collected by the Jilin-1 satellite constellation.

SAR images have strict requirements on the accuracy of radiometric calibration in the measurement of geophysical parameters and the realization of quantitative remote sensing applications.Therefore，the radiometric calibration verification of the SAR satellites is carried out.The relationship between the backscattering coefficient，the calibration constant and the image DN value is calculated with the radar equation，and the calibration verification experiment is carried out by using the active calibrator of Ningxia Zhongwei Calibration Field and its SAR image.The experimental results show that the absolute radiometric calibration accuracy of GF-3 02 satellite data is very high，in which the integration radiometric calibration accuracy is 0.65dB，while the peak calibration accuracy is 0.57dB；the radiometric calibration accuracy of the HISEA-1 satellite data is about 1.2dB.Maintaining the same wave position when calculating the calibration constant can effectively improve the stability of the calibration constant.

Low-frequency （LF） electromagnetic （EM） waves exhibit stronger transmission behavior under a plasma sheath， which has a positive impact on mitigating radio blackout. Previous work has established attenuation models for LF EM waves under the steady-state plasma sheath，but neglected the time-varying properties of the plasma， lacking an in-depth understanding of the channel characteristics. Therefore， this study focuses on the channel characteristics of dynamic plasma sheath on LF EM waves. The channel stochastic model of the dynamic plasma is established at LF EM wave bands， where the channel response of the dynamic plasma is merged with the colored-Gaussian time-varying electron density model. The first-order statistical properties of the dynamic plasma channel are obtained. The probability density function （PDF） of envelope P_r（r） is a power-Gaussian function， the PDF of the phase shift P_φ（φ） is a tangent-Gaussian function， and the power spectral density （PSD） function S_Hi（ω） is a colored noise function. To validate the effectiveness of the proposed channel statistical model， the muti-state numerical simulations are conducted， and the simulation results are in good agreement with the theoretical results. The electron density is 10¹⁸-10¹⁹/m³， the collision frequency is 1.5 GHz， and the frequency of LF EM waves is 1.30 MHz. When the electron density increases from 10¹⁸/m³ to 10¹⁹/m³， the degrees of random fluctuation on envelope and phase shift increase. The mean of P_r（r） increases from 1.33 to 34.04， and the standard deviation of P_r（r） increases from 0.13 to 14.34； the mean  of P_φ（φ） increases from 0.58 to 5.81， and the standard deviation of P_φ（φ） increases from 0.11 to 1.19； the PSDs are attenuated and broadened. The results reveal the channel characteristics of dynamic plasma at LF EM wave bands， which is significant for designing LF communication modulation algorithms and evaluating the performance of LF communication systems.

 The inter-satellite link network plays an important role in BeiDou global short message system，one or more nodes of the constellation may fail during system operation or space confrontation，which will affect the availability of the global short message system.According to the characteristics of BeiDou short message service and inter satellite link，a global short message simulation analysis method based on inter satellite link is designed，20 different constellation fault scenarios are designed，and the loss of short message service in different scenarios and at different time is counted.The results show that when the total number of failed satellites in the short message payload is less than or equal to 2，there is almost no impact on the short message service area.When the number of failed satellites in the short message payload is 3.6，the loss of service area is less than 10%，which indicates that the global short message system based on the inter satellite link can still maintain high service availability with a few satellite failures.

 For high-resolution images，the road situation is complex.And there are narrow roads or roads separated by buildings and shadows，leading to the problem of low extraction accuracy.In this paper，an improved model AP-LinkNet combining the atrous convolutional element and the parallel attention mechanism module is proposed，which can achieve higher detail extraction accuracy by expanding the receptive field and paying deep attention to road features in the downsampling coding process.The atrous convolution module expands the receptive field without changing the relationship between pixels on space.The parallel attention mechanism increases the attention to channel and spatial information during input image sampling.Combining the characteristics of the two mechanisms，the noise disturbance of complex road background is reduced and the overall accuracy is improved.The experimental results in this paper are compared with DeepLabV3+，U-Net，LinkNet and D-LinkNet.The F1 score and IOU on the DeepGlobe dataset are 80.69% and 78.65%，respectively.And the F1 score is 11.71%，5.24%，3.97% and 3.58% higher than the comparison models.The results show that the proposed model has higher accuracy and robustness，and has a good effect on extracting the narrow and complex road details from high-resolution images.