Current Issue
2023 Vol. 10, No. 1
Display Method:
Topic：Technology of Mars Orbiting Exploration
( Guest Editor：Professor ZHANG Yuhua, Shanghai Academy of Spaceflight Technology)
2023, 10(1): 3-10.
doi:10.15982/j.issn.2096-9287.2023.20220008
Abstract:
Based on the mission requirements of Mars orbiting exploration, and the constraints and environmental characteristics of interplanetary transfer and flight around Mars, the main technical difficulties of Mars orbiting exploration missions were analyzed. Based on the mission requirements and functional characteristics of Tianwen-1 orbiter, key technologies and solutions for Mars orbiting exploration were summarized, which mainly include autonomous security control for Mars orbit insert, autonomous management of long solar transit, integration of measurement control and data transmission, and multiple communication rates adaptive relay communication. Then, the development history, trend and innovation of the functions and technologies of the Mars orbiting exploration platform were reviewed, including Mars-to-Earth communication rate, navigation and orbital transformation capability, structural load-carrying and propulsion system. According to the future requirements of Mars exploration, the new capabilities that the orbiting exploration platform needs to develop were analyzed. Finally, the future direction of Mars orbiting exploration was analyzed.
Based on the mission requirements of Mars orbiting exploration, and the constraints and environmental characteristics of interplanetary transfer and flight around Mars, the main technical difficulties of Mars orbiting exploration missions were analyzed. Based on the mission requirements and functional characteristics of Tianwen-1 orbiter, key technologies and solutions for Mars orbiting exploration were summarized, which mainly include autonomous security control for Mars orbit insert, autonomous management of long solar transit, integration of measurement control and data transmission, and multiple communication rates adaptive relay communication. Then, the development history, trend and innovation of the functions and technologies of the Mars orbiting exploration platform were reviewed, including Mars-to-Earth communication rate, navigation and orbital transformation capability, structural load-carrying and propulsion system. According to the future requirements of Mars exploration, the new capabilities that the orbiting exploration platform needs to develop were analyzed. Finally, the future direction of Mars orbiting exploration was analyzed.
2023, 10(1): 11-18.
doi:10.15982/j.issn.2096-9287.2023.20220046
Abstract:
Tianwen-1, China’s first autonomous Mars exploration mission, faced many challenges in the process of interplanetary transfer and orbiting, such as long delay of data transmission between the orbiter and the Earth, many directional constraints during flight, and high requirements for autonomy and reliability. The autonomous navigation based on Mars optical target characteristic measurement, velocity vector control based on thrust direction compensation and angular momentum management based on multi-target pointing reference optimization were proposed. By adaptive edge extraction and accurate edge fitting based on ellipsoidal model for the characteristics of Mars time-varying target, high-precision navigation observation information of the target was obtained, and the accuracy of near-Mars navigation was better than 100 km and that of Mars circumnavigation was better than 2 km. The real-time estimation of thrust direction based on accelerometer measurement and attitude feedforward compensation were used to make the braking capture control accuracy reach the order of millimeter/second. Combined with the multi-target pointing constraint, attitude reference optimization design was carried out with the goal of global optimal jamming torque, to guarantee the autonomous flight control without ground support for more than 30 days. The proposed method was applied to the GNC subsystem of Tianwen-1 surrounding device. The in-orbit flight results of Tianwen-1 show that the proposed method can meet the constraints of autonomous control and autonomous management of interstellar flight, which provides important reference for subsequent deep-space exploration model missions.
Tianwen-1, China’s first autonomous Mars exploration mission, faced many challenges in the process of interplanetary transfer and orbiting, such as long delay of data transmission between the orbiter and the Earth, many directional constraints during flight, and high requirements for autonomy and reliability. The autonomous navigation based on Mars optical target characteristic measurement, velocity vector control based on thrust direction compensation and angular momentum management based on multi-target pointing reference optimization were proposed. By adaptive edge extraction and accurate edge fitting based on ellipsoidal model for the characteristics of Mars time-varying target, high-precision navigation observation information of the target was obtained, and the accuracy of near-Mars navigation was better than 100 km and that of Mars circumnavigation was better than 2 km. The real-time estimation of thrust direction based on accelerometer measurement and attitude feedforward compensation were used to make the braking capture control accuracy reach the order of millimeter/second. Combined with the multi-target pointing constraint, attitude reference optimization design was carried out with the goal of global optimal jamming torque, to guarantee the autonomous flight control without ground support for more than 30 days. The proposed method was applied to the GNC subsystem of Tianwen-1 surrounding device. The in-orbit flight results of Tianwen-1 show that the proposed method can meet the constraints of autonomous control and autonomous management of interstellar flight, which provides important reference for subsequent deep-space exploration model missions.
2023, 10(1): 19-27.
doi:10.15982/j.issn.2096-9287.2023.20220002
Abstract:
To optimize ignition attitude design during Mars capture and braking of China’s first autonomous Mars exploration mission “Tianwen-1”, an analysis idea and a solution under the constraint of the whole vehicle were proposed. Firstly, the trajectory dynamics model in the capture phase was established. According to the pre-capture trajectory and the post-capture target trajectory, optimal thrust direction and ignition time in the orbit plane were solved by Newton iteration method with minimum fuel consumption as optimization objective, and thrust vector was obtained. Combined with illumination and measurement and control constraints of the detector, deflection range around thrust direction was determined. Finally, referring to the layout of star sensors, occlusion of star sensors by celestial bodies at different deflection angles during the whole process was analyzed, and the number of available star sensors and the available duration were calculated. The optimal ignition attitude was determined according to the principle of optimal available duration. The actual on-track braking capture results show that the semi-major axis deviation after track control is less than 947.122 km (semi-major axis variation of 102346.152 km), and the eccentricity deviation is less than 0.0021. At the same time, the whole process can meet the requirements of the whole device for measurement and control and illumination. During the whole acquisition process, at least two star sensors are available at any time, and compared with the telemetry results, the simulation error of the available duration of star sensors is less than 0.225 h.
To optimize ignition attitude design during Mars capture and braking of China’s first autonomous Mars exploration mission “Tianwen-1”, an analysis idea and a solution under the constraint of the whole vehicle were proposed. Firstly, the trajectory dynamics model in the capture phase was established. According to the pre-capture trajectory and the post-capture target trajectory, optimal thrust direction and ignition time in the orbit plane were solved by Newton iteration method with minimum fuel consumption as optimization objective, and thrust vector was obtained. Combined with illumination and measurement and control constraints of the detector, deflection range around thrust direction was determined. Finally, referring to the layout of star sensors, occlusion of star sensors by celestial bodies at different deflection angles during the whole process was analyzed, and the number of available star sensors and the available duration were calculated. The optimal ignition attitude was determined according to the principle of optimal available duration. The actual on-track braking capture results show that the semi-major axis deviation after track control is less than 947.122 km (semi-major axis variation of 102346.152 km), and the eccentricity deviation is less than 0.0021. At the same time, the whole process can meet the requirements of the whole device for measurement and control and illumination. During the whole acquisition process, at least two star sensors are available at any time, and compared with the telemetry results, the simulation error of the available duration of star sensors is less than 0.225 h.
2023, 10(1): 28-36.
doi:10.15982/j.issn.2096-9287.2023.20210090
Abstract:
ITo deal with the problems of ultra-long distance and large dynamic communication under a maximum distance of 400 million kilometers of Tianwen-1 Mars Orbiter, the TT&C and data transmission communication system of Tianwen-1 Mars Orbiter realized high-sensitivity acquisition of -156dbm weak signals and adaptive data transmission and reception under large dynamic conditions through integrated TT&C and data transmission technology of multi-antenna beam shaping, multi bit rate adaptive transmission and reception processing technology, high-sensitivity signal acquisition technology, electromagnetic interference suppression technology under ultra-high sensitivity and high-precision stable pointing technology of large aperture antenna under extremely low temperatures. Except for celestial block, the whole process was 100% covered by the earth communication link and beam, and data transmission rate to the earth was up to 1Mbps at the farthest distance of 400 million kilometers. This technology has been examined and verified in Tianwen-1 Mars exploration mission, and can provide reference for the design and on-orbit work of the TT&C data transmission communication system in subsequent deep space exploration missions.
ITo deal with the problems of ultra-long distance and large dynamic communication under a maximum distance of 400 million kilometers of Tianwen-1 Mars Orbiter, the TT&C and data transmission communication system of Tianwen-1 Mars Orbiter realized high-sensitivity acquisition of -156dbm weak signals and adaptive data transmission and reception under large dynamic conditions through integrated TT&C and data transmission technology of multi-antenna beam shaping, multi bit rate adaptive transmission and reception processing technology, high-sensitivity signal acquisition technology, electromagnetic interference suppression technology under ultra-high sensitivity and high-precision stable pointing technology of large aperture antenna under extremely low temperatures. Except for celestial block, the whole process was 100% covered by the earth communication link and beam, and data transmission rate to the earth was up to 1Mbps at the farthest distance of 400 million kilometers. This technology has been examined and verified in Tianwen-1 Mars exploration mission, and can provide reference for the design and on-orbit work of the TT&C data transmission communication system in subsequent deep space exploration missions.
2023, 10(1): 37-43.
doi:10.15982/j.issn.2096-9287.2023.20210086
Abstract:
In this article, a method that can solve the problems of thermal design of the pipe that was suitable for the characteristics of space environment of the Mars Probe was proposed. By adopting optimized heating power, suitable number of layers and suitable zone of the heaters, thermal control of the pipeline under complex external heat flow was realized. In the design of propulsion pipeline of Tianwen-1 Mars Orbiter, this method was analyzed and verified, and influencing factors, such as the change of ambient temperature, whether the propulsion pipeline had working fluid, whether it was exposed to the sun, the number of coating layers and heating power, were also analyzed. Research shows that this method had high adaptability to the environment and could adapt to the whole process of the orbiter flight and the conditions of orbit change; more attention should be paid to the number of coating layers and heating power in the future; the extravehicular pipeline was greatly affected by sunlight, exposure to sunlight should be avoided as much as possible in the design process. The research findings above can provide some reference for thermal control design of the propulsion pipeline in subsequent deep space explorations.
In this article, a method that can solve the problems of thermal design of the pipe that was suitable for the characteristics of space environment of the Mars Probe was proposed. By adopting optimized heating power, suitable number of layers and suitable zone of the heaters, thermal control of the pipeline under complex external heat flow was realized. In the design of propulsion pipeline of Tianwen-1 Mars Orbiter, this method was analyzed and verified, and influencing factors, such as the change of ambient temperature, whether the propulsion pipeline had working fluid, whether it was exposed to the sun, the number of coating layers and heating power, were also analyzed. Research shows that this method had high adaptability to the environment and could adapt to the whole process of the orbiter flight and the conditions of orbit change; more attention should be paid to the number of coating layers and heating power in the future; the extravehicular pipeline was greatly affected by sunlight, exposure to sunlight should be avoided as much as possible in the design process. The research findings above can provide some reference for thermal control design of the propulsion pipeline in subsequent deep space explorations.
On-orbit Thermal Design and Beam Pointing Error Impact Analysis of High Gain Antenna of Mars Orbiter
2023, 10(1): 44-51.
doi:10.15982/j.issn.2096-9287.2023.20210089
Abstract:
The technical difficulties on thermal design, suitability under –195℃ ultra-low temperature condition, analysis and verification of beam pointing error caused by thermal distortion for high gain antenna of Mars orbiter were summarized, and relevant design and verification were completed. Based on thermal design state, the temperature field and thermal distortion of high gain antenna under typical working conditions during the operation on orbit were simulated and analyzed. A vacuum thermal distortion measurement system for large aperture reflector antenna was designed and developed. According to vacuum thermal distortion test data, the beam pointing error was evaluated by a hybrid simulation method. The results show that the maximum beam pointing error is 0.028°, and the gain loss is less than 0.5dB, both of which are within the design margin. The on-orbit test results confirm that the beam pointing performance is consistent with the evaluation, which effectively verifies the accuracy of the thermal design and verification method.
The technical difficulties on thermal design, suitability under –195℃ ultra-low temperature condition, analysis and verification of beam pointing error caused by thermal distortion for high gain antenna of Mars orbiter were summarized, and relevant design and verification were completed. Based on thermal design state, the temperature field and thermal distortion of high gain antenna under typical working conditions during the operation on orbit were simulated and analyzed. A vacuum thermal distortion measurement system for large aperture reflector antenna was designed and developed. According to vacuum thermal distortion test data, the beam pointing error was evaluated by a hybrid simulation method. The results show that the maximum beam pointing error is 0.028°, and the gain loss is less than 0.5dB, both of which are within the design margin. The on-orbit test results confirm that the beam pointing performance is consistent with the evaluation, which effectively verifies the accuracy of the thermal design and verification method.
2023, 10(1): 52-57.
doi:10.15982/j.issn.2096-9287.2023.20210091
Abstract:
According to design characteristics and configuration of Mars orbiter, the whole link time calibration of mars orbiter was studied and validated, the time transmission path of Mars orbiter was analyzed, and a whole link time calibration method suitable for Mars exploration missions was given. Time calibration of hardware equipment, software design and system configuration was introduced. The actual application results show that the calibration method of the whole link time of Mars orbiter was reasonable, the launch day timing was accurate, and the ground test data were verified by the actual operation in orbit. This paper provides important reference for the design of time calibration system and calibration method for subsequent Mars exploration and related deep space missions.
According to design characteristics and configuration of Mars orbiter, the whole link time calibration of mars orbiter was studied and validated, the time transmission path of Mars orbiter was analyzed, and a whole link time calibration method suitable for Mars exploration missions was given. Time calibration of hardware equipment, software design and system configuration was introduced. The actual application results show that the calibration method of the whole link time of Mars orbiter was reasonable, the launch day timing was accurate, and the ground test data were verified by the actual operation in orbit. This paper provides important reference for the design of time calibration system and calibration method for subsequent Mars exploration and related deep space missions.
2023, 10(1): 58-65.
doi:10.15982/j.issn.2096-9287.2023.20220080
Abstract:
In this paper, the mission orbit design and analysis of a potential extended mission, Phobos close approach exploration, was carried out. The state at the end of the main mission was used as the input of the extended mission in this paper. Through analysis, it was concluded that Mars perturbation force could be used to adjust the argument of perigee, and the intersection frequency was related to the value of semi-major axis and eccentricity. Orbit descent maneuver should be performed to increase the number of intersections. As a result, the possibility of conducting aero-braking in order to reduce fuel consumption was analyzed. Finally, phase adjustment maneuver was calculated to complete the Phobos close approach exploration mission. The orbit design results and the velocity increment are given by simulation. The results of this paper can provide reference for orbit design of Tianwen-1 orbiter’s extended missions.
In this paper, the mission orbit design and analysis of a potential extended mission, Phobos close approach exploration, was carried out. The state at the end of the main mission was used as the input of the extended mission in this paper. Through analysis, it was concluded that Mars perturbation force could be used to adjust the argument of perigee, and the intersection frequency was related to the value of semi-major axis and eccentricity. Orbit descent maneuver should be performed to increase the number of intersections. As a result, the possibility of conducting aero-braking in order to reduce fuel consumption was analyzed. Finally, phase adjustment maneuver was calculated to complete the Phobos close approach exploration mission. The orbit design results and the velocity increment are given by simulation. The results of this paper can provide reference for orbit design of Tianwen-1 orbiter’s extended missions.
2023, 10(1): 66-71.
doi:10.15982/j.issn.2096-9287.2023.20220007
Abstract:
To achieve the goal of accuraetly pointing to particular targets for the narrow-FOV multi-spectral camera on the mast, an accuracy mast pointing method was proposed. The mast kinetic model, the iterative solution method of mast control parameters, and the working flow of rover target detection were designed. An error analysis of the method was conducted. Through the practice of China’s first Mars exploration mission, the method is proved to satisfy the demand for accuracy pointing of the multi-spectral camera.
To achieve the goal of accuraetly pointing to particular targets for the narrow-FOV multi-spectral camera on the mast, an accuracy mast pointing method was proposed. The mast kinetic model, the iterative solution method of mast control parameters, and the working flow of rover target detection were designed. An error analysis of the method was conducted. Through the practice of China’s first Mars exploration mission, the method is proved to satisfy the demand for accuracy pointing of the multi-spectral camera.
2023, 10(1): 72-79.
doi:10.15982/j.issn.2096-9287.2023.20210155
Abstract:
The IMU of Tianwen-1 is the core product of its navigation system; during the installation of gyro and accelerometer in IMU installation deviation and nonlinear scale factor occur, leading to the non-orthogonality of installation matrix and affecting the accuracy of IMU inertial navigation. In this paper, the orthogonality of gyro and accelerometer installation matrix was analyzed, and the orthogonalization algorithm of installation matrix for row vector was proposed, which improves the orthogonality of gyro and accelerometer installation matrix and reduces the distortion of installation error angle in the process of orthogonalization. The calibration test of IMU inertial navigation under typical working conditions was carried out. The test results show that after the installation matrix was orthogonalized according to row vector, the attitude accuracy of IMU inertial navigation was improved by 15.8%~54.7%, and the position accuracy was improved by 45.2%~85.7%. Adopting the above method, the percentage of static position and attitude performance improvement under various working conditions is consistent and not related to the test time; the percentage of dynamic position and attitude performance improvement under various working conditions is consistent and not related to the cumulative sum of rotation angle.
The IMU of Tianwen-1 is the core product of its navigation system; during the installation of gyro and accelerometer in IMU installation deviation and nonlinear scale factor occur, leading to the non-orthogonality of installation matrix and affecting the accuracy of IMU inertial navigation. In this paper, the orthogonality of gyro and accelerometer installation matrix was analyzed, and the orthogonalization algorithm of installation matrix for row vector was proposed, which improves the orthogonality of gyro and accelerometer installation matrix and reduces the distortion of installation error angle in the process of orthogonalization. The calibration test of IMU inertial navigation under typical working conditions was carried out. The test results show that after the installation matrix was orthogonalized according to row vector, the attitude accuracy of IMU inertial navigation was improved by 15.8%~54.7%, and the position accuracy was improved by 45.2%~85.7%. Adopting the above method, the percentage of static position and attitude performance improvement under various working conditions is consistent and not related to the test time; the percentage of dynamic position and attitude performance improvement under various working conditions is consistent and not related to the cumulative sum of rotation angle.
2023, 10(1): 80-87.
doi:10.15982/j.issn.2096-9287.2023.20220006
Abstract:
China’s Tianwen-1 probe orbiting Mars provides necessary conditions for Mars-to-Earth Mars radio occultation observation, and can effectively support the exploration of Mars atmosphere and ionosphere retrieval. In this paper, the first domestic Mars radio occultation observation experiment based on Tianwen-1 was introduced. Firstly, Tianwen-1 was used to forecast the orbit and the occultation observation arc of the ground deep space station. Then, deep space stations were organized to observe the entire process of Tianwen-1 Mars occultation, and the original downlink signals of the probe were sampled and recorded. Finally, the self-developed deep space open-loop measurement software was used to process and analyze the downlink signals of Tianwen-1, to extract the radio occultation features of Mars. The results show that the amplitude diffraction speckles and frequency warping features in the signal were successfully extracted, which confirms that the Mars-to-Earth Mars radio occultation event has been effectively observed, and important technical experience and measurement data have been accumulated for subsequent scientific research on Mars atmospheric exploration based on Tianwen-1.
China’s Tianwen-1 probe orbiting Mars provides necessary conditions for Mars-to-Earth Mars radio occultation observation, and can effectively support the exploration of Mars atmosphere and ionosphere retrieval. In this paper, the first domestic Mars radio occultation observation experiment based on Tianwen-1 was introduced. Firstly, Tianwen-1 was used to forecast the orbit and the occultation observation arc of the ground deep space station. Then, deep space stations were organized to observe the entire process of Tianwen-1 Mars occultation, and the original downlink signals of the probe were sampled and recorded. Finally, the self-developed deep space open-loop measurement software was used to process and analyze the downlink signals of Tianwen-1, to extract the radio occultation features of Mars. The results show that the amplitude diffraction speckles and frequency warping features in the signal were successfully extracted, which confirms that the Mars-to-Earth Mars radio occultation event has been effectively observed, and important technical experience and measurement data have been accumulated for subsequent scientific research on Mars atmospheric exploration based on Tianwen-1.
Cognitive Graph for Autonomous Deep Space Mission Planning and Multi-Constraints Collision Detection
2023, 10(1): 88-96.
doi:10.15982/j.issn.2096-9287.2023.20220064
Abstract:
To deal with the multi-constraints in multi-subsystems coordination mechanism in deep space exploration mission planning, in this paper a cognitive graph architecture and a multi-attributes constraint conflict detection method were proposed for deep space exploration mission planning. In this paper, the graph representation method was adopted to realize knowledge modeling of task planning, the state transition diagram was constructed into triples to realize rule matching during task planning, and a multi-attributes constraint conflict detection algorithm was proposed based on the graph model inference method, so multi-subsystems cognitive reasoning and constraint conflict testing for task planning were realized. Simulation experiments were carried out with different scales of deep space exploration mission planning examples. The experimental results show that compared with genetic algorithm, traditional heuristic algorithm, constrained heuristic algorithm, and evolutionary neural network algorithm, the method proposed in this paper can effectively shorten planning time, and reduce the solution space and memory consumption, effectively improving the success rate and feasibility of deep space exploration mission planning.
To deal with the multi-constraints in multi-subsystems coordination mechanism in deep space exploration mission planning, in this paper a cognitive graph architecture and a multi-attributes constraint conflict detection method were proposed for deep space exploration mission planning. In this paper, the graph representation method was adopted to realize knowledge modeling of task planning, the state transition diagram was constructed into triples to realize rule matching during task planning, and a multi-attributes constraint conflict detection algorithm was proposed based on the graph model inference method, so multi-subsystems cognitive reasoning and constraint conflict testing for task planning were realized. Simulation experiments were carried out with different scales of deep space exploration mission planning examples. The experimental results show that compared with genetic algorithm, traditional heuristic algorithm, constrained heuristic algorithm, and evolutionary neural network algorithm, the method proposed in this paper can effectively shorten planning time, and reduce the solution space and memory consumption, effectively improving the success rate and feasibility of deep space exploration mission planning.
