Abstract:The space launch technology is an integrated technology of sending satellites and other payloads into predetermined orbits.At present，it mainly includes the launch vehicle technology，the construction and selection of launch modes，the launch site support technology，etc.In the future，with technological breakthroughs and innovations in comprehensive applications，the main components and implementation methods of space launch technology will undergo earth-shaking changes.In this paper，the current status and future development trends of space launch technology at home and abroad are overviewed.The overall status，applications，and characteristics of space launch technology are comprehensively analyzed，and the main breakthrough directions and technological implementation ideas for future development and transformation are prospected.

Abstract:A digital twin reference architecture for land-launched supporting systems is proposed to meet the application requirements of remote monitoring and diagnosis，intelligent maintenance，and autonomous decision and control in space land-launched supporting systems.The key technologies for implementing digital twins are extracted.A simulation platform based on the reference architecture is developed for the tower lifting and docking of China's first solid-liquid bundled launch vehicle.Through actual operation assessment，it is verified that based on virtual real space interaction mapping and real time dynamic simulation，the platform can improve the safety and efficiency of lifting docking work by enriching the monitoring information of lifting scenes.Meanwhile， the rationality of the digital twin reference architecture design and the feasibility of the technical roadmap are verified.

Abstract:The long March 6A (CZ-6A) is the first medium-sized low-temperature powered launch vehicle with solid-liquid bundled configuration in China.In this paper，the basic situation of the test launch mission of the CZ-6A is briefly introduced，and the technical characteristics，process characteristics，task support characteristics，and countermeasures of the CZ-6A during launch missions are summarized and analyzed.The development direction of the rapid test launch technology based on solid-liquid bundled launch vehicles is put forward，and the development needs of the application of new launch vehicle technology，the optimization of the test launch process，the capacity building of the launch site，etc.are analyzed，providing useful reference for the model development and the improvement of the test launch capacity of the launch site.

Abstract:The implementation process of sea launch is bound to be affected and restricted by the meteorological and marine environment，which directly affects the selection of sea launch windows and launch safety.In order to avoid the occurrence of major equipment damage，long-term window delay，and personnel safety accidents in the sea launch under complex weather conditions，in this paper，the distribution characteristics and change rules of the wave field，wind field，temperature field，and precipitation field in the Yellow Sea are analyzed，and the implementation phase and seasonal prevention trend of the sea launch are designed and analyzed based on the characteristics of seasonal changes.It provides reference experience for the implementation of sea launch under extreme weather conditions in different seasons.

Abstract:Launching rocket over sea has great advantages in improving the rocket carrying capacity and reducing the risk of debris falling.China has successfully implemented sea launch missions of multiple types of solid rocket.Compared with solid rocket，liquid-oxygen kerosene rocket has higher specific impulse and environmental friendliness.According to the characteristics and laws of the land-based launch of liquid-oxygen kerosene rocket，the process and implementation plan of solid rocket launch missions over sea and the basic operation plans of port base，sea launch ship，carrier rocket，support ship，and other parts of the sea launch system are studied，and the implementation process of sea launch missions is proposed.The importance of diversionary release，the zero-second off and automatic docking of connector，and the unattended propellant filling technologies in sea launch rockets and the key problems to be solved are analyzed.

Abstract:The recyclability and reuse of launch vehicles not only can reduce the launch costs，but also can increase the launch density to meet the needs of high-density launches.It is a technology that must be developed by humans to explore space.The vertical return-to-sea recovery method has a high-precision and high-stable landing point，by which both the threat to the safety of the people in the landing area and the impact of insufficient rocket carrying capacity can be reduced.Since the sub-stages of the “Falcon 9” rocket were successfully recovered vertically at sea and reused，researchers from various countries have paid attention to and explored the vertical recovery technology of rocket sub-stages at sea.In this paper，the advantages and characteristics of maritime vertical recovery launch vehicles are described.Then，the development status of maritime vertical recovery launch vehicles is sorted out，and the key technologies included in the process of recovering a rocket at sea are analyzed.Finally，the development trends of maritime vertical recovery launch vehicles are summarized.

Abstract:Feature event synthesis and ballistic fusion are the most important tasks in the process of space launch.The flight status of a launch vehicle can be intuitively reflected through the occurrence time of feature event and its flight ballistic trajectory.In order to further improve the effectiveness of feature event synthesis and ballistic fusion，based on the remote and external measurement information，the information sources involved in the feature event synthesis and ballistic fusion are classified，their influence factors are analyzed，and the corresponding information fusion strategies are proposed.By adopting an improved fusion strategy，the accuracy and effectiveness of the feature event time calculation is further improved，and the ballistic fusion results are improved enough to meet the requirements of status display and safety control missions during the space launch flight.

Abstract:Launch vehicles are vulnerable to multipath fading during the static tests in the tower，which leads to intersymbol interference in the telemetry signals.In this paper，the constant modulus algorithm (CMA) is used to carry out blind equalization research on the pulse code modulation/frequency modulation (PCM/FM) telemetry signals in multipath channels.Theoretical analysis and MATLAB simulation are carried out for the intersymbol interference in the telemetry channels，and a blind equalization function test platform is built to carry out experimental verification.The results show that the CMA has a fast convergence speed and a low bit error rate (BER)，and has good robustness and practicability to the multipath interference.

Abstract:In response to the complex factors and hierarchical uncertainties involved in space launch safety risk assessment，an indicator framework for the hierarchical space launch safety risk assessment is presented.A normal distribution density function is used to refine the weighting of indicators determined by the analytic hierarchy process，so that the risk assessment results are more scientific and reasonable.The indicator framework helps to identify the key priorities for the safety risk management in space launch activities and to optimize the prevention and control measures.

Abstract:In order to solve the problem that the outfield phase calibration of large phased array radar cannot guarantee the calibration accuracy due to the influence of wind，a high-precision outfield phase grading calibration method is proposed.The laser calibration method is used to measure the sloshing curve and the maximum sloshing speed of the calibration source under wind load conditions.According to the radar operating frequency band and the calibration accuracy requirements，the minimum calibration duration guaranteeing the accuracy is calculated when the sloshing speed of the calibration source is maximum.The obtained minimum calibration duration is then used as the basis for the size division of the hierarchical subarray，and the full array outfield calibration is completed through multi-level calibration.The test results show that under the level 5 wind load condition，the root mean square (RMS) of the X-band phase calibration accuracy is less than 5.8°，and the maximum grating lobe level is reduced by 9 dB，which meets the accuracy requirements of the analog phase shifter.

Abstract:In response to the characteristics of the three-horizontal test launch mode，an influence analysis of vertical arm on the ground-wind loads of a launch vehicle is carried out so as to improve the adaptability of the ground-wind load condition of the launch vehicle to its launch site under large ground-wind loads，reduce the design load and structural weight of the launch vehicle，and improve the launch efficiency.The ground-wind load of the launch vehicle is calculated based on the generalized displacement and the generalized load.Based on the structural characteristics of the vertical arm，the influence of the vertical arm stiffness，the support cylinder stiffness，the clamp number，and the clamp position on the ground-wind loads of the launch vehicle is quantitatively analyzed.The stiffness of the vertical arm，the number and position of the hoops have a great influence on the ground-wind loads of the launch vehicle.The bending moment at the root can be reduced by 24.8% by increasing the stiffness of the vertical arm，and the bending moment at the root can be reduced by 38% by increasing the hoop between the I.stages.The stiffness of the support cylinder has almost no effect on the ground-wind loads of the launch vehicle.

Abstract:The development and utilization of lunar resources has become not only a hot research field in global deep space exploration but also an endogenous driving force for the development of deep space exploration from exploration to utilization.It is widely acknowledged that rare resources such as 3He，titanium，and rare earth are abundant on the Moon.However，limited by the high technical complexity，large scale，poor repeatability，and poor economy of traditional lunar resource return methods，the development and utilization of lunar resources are still in the “exploration” stage.There is yet to be an economically viable technical solution for achieving efficient “utilization”.Therefore，a new technology for lunar return system is proposed.It is based on existing magnetic levitation and rotating flywheel technologies，with magnetic levitation rotating ejection as the core technology.In particular，the new technology can take full advantages of the lunar surface environmental factors such as low temperature and weak gravity，so that lunar resources can be transported back to the Earth in a repeatable，low-cost，and high-frequency manner.

Abstract:In response to the issues such as sensor noise interference and gyroscope drift during the attitude measurement of low Earth orbit (LEO) satellites，a satellite attitude measurement method based on the Madgwick-extended Kalman filter (EKF) fusion algorithm is proposed.This method uses the data of multiple sensors，e.g.，gyroscopes，accelerometers，and magnetometers，for fusion，and leverages the advantages of both the Madgwick algorithm and the EKF algorithm to achieve attitude measurement.Initially，the Madgwick algorithm is used to calculate the initial attitude with the data measured by multiple sensors.Subsequently，based on the initial attitude and the measured data，the EKF algorithm is used for data fusion and noise filtering so as to obtain the final accurate attitude estimation.The experimental results indicate that compared with the Madgwick algorithm，the fusion algorithm improves the measurement accuracy by 65.8%，and exhibits high robustness.This method provides an effective solution for the attitude measurement of LEO satellites.

Abstract:In order to investigate the unsteady characteristics in the internal flow field of proportional variable solid attitude control motor，a two-dimensional axisymmetric model of proportional pintle thruster is established.The dynamic mesh method and custom inlet conditions are used to simulate the working mode of the thruster which inlet pressure varies with the throat area.The variations of the performance parameters of the internal flow field are obtained.The results show that the characteristics such as subsonic recirculation zones，oblique shock waves，and flow separation will appear in the internal flow field during the unsteady working process.The pressures of the inlet，the pintle wall，and the nozzle wall all increase when the distance between the pintle and the throat decreases，the thrust of the thruster gradually increases when the pintle load increases，and thus the continuous thrust regulation is achieved.The working frequency will aggravate the pressure fluctuation of the head during the pintle advance.The larger the convergence angle of the pinhead is，the smaller the head recirculation zone is.When the throat area is fixed，the higher the burning rate pressure index is，the larger the variation ranges of engine pressure and thrust are.Therefore，it is necessary to choose an appropriate pressure exponent to achieve a wide range of thrust adjustment.

Abstract:After the ignition of the final-stage engine，the launch vehicle guided by the guidance system will finally reach the orbit injection point and obtain an injection speed，and the satellite will enter the operational orbit.The final-stage flight dynamics model of a launch vehicle is in the form of nonlinear differential equations，which makes it difficult to obtain the attitude change characteristics of the launch vehicle by means of analytical methods and then control the state variables during the flight process of the launch vehicle.In this paper，the orbit injection constraint conditions of the launch vehicle are converted to a performance index function for optimal control，and the dynamic equations are solved by means of the combination of the Pontryagin minimum principle and the Newton gradient method，so that the final flight standard orbit is obtained.In the process of modeling the launch vehicle dynamics，due to the difficulties such as the parameters cannot be accurately measured，there are inevitably modeling errors，and thus the actual flight orbit of the launch vehicle will deviate from the standard one.The model is linearized，and the state feedback is introduced，which can make the actual flight orbit close to the standard one and improve the accuracy required for satellites loading into orbits.The simulation results show that the guidance algorithm can effectively reduce the orbit injection error of the launch vehicle.

Abstract:In response to the application requirements of multi-payload collaborative observation and consistent measurement for high-orbit remote sensing satellites，a platform configuration design scheme is proposed based on the preliminary research on the overall technical scheme and the configuration research on existing common platforms for on-orbit assembly spacecrafts and high-orbit satellites.The platform is launched by the CZ-5 launch vehicle，and is deployed in orbit.The overall configuration of “grid format center bearing cylinder + plate + truss” is adopted，and the detailed design works are carried out on the main transmission path，storage tank bearing structure，grid format center bearing cylinder，etc.The structural products are designed，and a finite element model is established for the satellite platform.The simulation analysis shows that the first-order frequencies of the satellite platform can meet the frequency requirements of the launch vehicle.Based on the standardized and universal platform interface design，the platform has the ability to be scalable and repairable，along with greatly improved robustness.Based on the main load-bearing design of grid format center bearing cylinder，the load-bearing capacity of the platform is enhanced，and the internal thermal environment of the platform is improved.This design scheme can provide a valuable reference for the design of high-orbit remote sensing large-platforms based on on-orbit assembly and maintenance.

Abstract:To improve the thermal resistance of an innovative monopropellant thruster injector，the effects of the structure parameters on the thermal resistance and structure strength are analyzed by means of simulation calculation，and the response surface methodology (RSM) is used to optimize the support structure of the injector.The simulation results show that within the calculation range，the height of the support structure has the greatest effect on the thermal resistance performance of the support structure，followed by the thickness of the support structure，and finally the diameter of the support structure hole.Moreover，the thermal resistance increases with the increase in the height of the support structure，while decreases when the thickness of the support structure and the diameter of the support structure hole increase.In addition，the diameter of the support structure hole has the greatest effect on the maximum equivalent stress of the support structure，followed by the height of the support structure，and finally the thickness of the support structure.The maximum equivalent stress of the support structure increases with the increase in the diameter of the support structure hole，while decreases when the height and thickness of the support structure increase.The structure strength of the support structure optimized with the RSM meets the mechanical requirements of the engine，and the thermal resistance of the injector is obviously improved.

Abstract:The applications of long-period deformation monitoring are increasingly expanding with the development of domestic autonomous synthetic aperture radar (SAR) satellites，differential interferometric synthetic aperture radar (D-InSAR) technology，and derived D-InSAR technology，primarily focusing on the repetitive temporal observations.For the ground mission planning systems of remote sensing satellites，scheduling and managing a large number of repeated time-series missions，so as to meet the observation requirements，is the key to improve the SAR satellite operation performance with deformation surveying missions.In this paper，a planning framework of time-series InSAR missions for SAR satellites is designed，considering the characteristics of the time-series InSAR missions including sequentiality，consistency，and periodicity.It aims to detect the conflict between the sequence mission groups with the consideration of their specific characteristics.The framework is used to optimize and update the existing planning system.The results show that the framework can quickly and automatically resolve the sequence mission conflict，which verifies its effectiveness.This indicates that the designed framework can offer a valuable reference for the planning and management of long-term sequence missions.

Abstract:When a high thrust liquid oxygen kerosene rocket engine operates stably，the combustion chamber reaches a supercritical environment.However，the existing droplet evaporation combustion model at present is only applicable to subcritical environments，and cannot be used in supercritical environments.In view of this，in this paper，a simulation calculation model is established for kerosene droplet combustion in sub/supercritical environments，and the effects of the ambient parameters on the combustion characteristics of kerosene droplets in sub/supercritical environments are studied.The results show that as the ambient temperature increases，the flame temperature increases significantly，and the ignition time，migration time，and droplet life all decrease.Besides，when the ambient pressure increases，the dimensionless flame radius of kerosene droplet combustion decreases，the flame temperature slightly increases，and the ignition time，migration time，and droplet life all decrease.In a pressure oscillation environment，the oscillation frequencies of the time dependent curves of the droplet evaporation rate，dimensionless flame radius，and flame temperature of kerosene droplet combustion are consistent with the oscillation frequencies of the ambient pressure，and the flame temperature is particularly sensitive to the ambient pressure oscillation.

Abstract:In response to the requirements for improving the emergency observation efficiency of multiple targets of in-orbit small synthetic aperture radar (SAR) satellites in key areas，a design method for the translational invariant mode based on small SAR satellites is proposed.First，the design method is introduced，and the range dimension and large angle scanning capability of loaded planar phased array antenna are designed.Then，in view of regional multiple targets，a conditional trigger target-decision strategy and an on-board radar working parameter calculation strategy are proposed.Finally，based on the task-decision strategy and the task-planning model established in this paper，the simulation analyses of multi-target observation efficiency evaluation are carried out in four working modes，respectively，i.e.，left view，side view，translational invariant，and left and right maneuvering side view.The results show that compared with the side view mode，the target observation efficiency of the translational invariant mode can be improved to 41%.Compared with the left and right maneuvering side view mode，the target observation efficiency of the translational invariant mode can be improved to 73%.Therefore，the translational invariant mode designed in this article can effectively improve the observation efficiency towards regional multiple targets.