Deep space exploration technology
2020, 49(5): 20190454.
doi: 10.3788/IRLA20190454
Focal plane assembly of space remote sensor is a key component of space remote sensor, which is used to finish the transition function of the light signal into electrical signal. The focal plane assembly should have the characteristics of high splicing accuracy, high stability and high lightweight performance. In view of the function requirement of a deep space remote sensor with push-scan imaging and staring imaging, a focal plane assembly whose substrate was common with CCD detector and CMOS detector was designed, the focal plane assembly included focal plane substrate, CCD component, CMOS component, video processing circuit board, and so on. With a reasonable layout, the focal plane assembly was designed with three pieces of CCD and two pieces of CMOS, which was a compact structure and had a good heat dissipation effect. Moreover, the electromagnetic compatibility performance of focal plane assembly was improved obviously with the means of copper segment and box structure covering. After the assembling of focal plane assembly, the lapping error of CCD detector was better than ±2 μm, the collinearity and parallelism error of detector of CCD and CMOS was better than ±2 μm, the coplanarity error was better than ±2.5 μm. Finally, the force and thermal tests were carried out for the focal plane assembly, and the collinearity, parallelism and coplanarity errors of the detector did not change, indicating that the focal plane component has high enough splicage accuracy and stability. The fundamental frequency of the focal plane assembly is 135 Hz, which had sufficient dynamic stiffness. At the same time, the electromagnetic compatibility test was carried out on the space remote sensor, with good performance.
2020, 49(5): 20190458.
doi: 10.3788/IRLA20190458
Demand for autonomous navigation for mars exploration during the surround segment, a high-precision autonomous navigation method using Mars ontology was proposed based on the initial orbital parameters and the Mars image was taken by the optical navigation camera. The method first used the initial orbital parameters to obtain a projection of Mars in the camera phase plane, then matched the projection map with the Mars image to get the edge map of Mars, using the edge map for accurate ellipse fitting to achieve detector-Mars line of sight distance and line of sight vector measurement. In the process of algorithm simulation, the problems of image rotation, translation and size transformation that may be encountered in engineering implementation were fully considered. The simulation results show that the proposed image fusion measurement algorithm using prior information, the accuracy and reliability is improved more than the navigation method using mars image alone, which can meet the mission requirements of Mars exploration during the surround segment.
2020, 49(5): 20190460.
doi: 10.3788/IRLA20190460
Without atmosphere, the lunar surface is gradually evolved into lunar soil by the space weathering. The space weathering generates lunar soil and matures it. This progress changes the morphological structure and the spectral characteristics. Thus the spectral characteristics of lunar soil contains information about the space weathering of the moon's surface. Lunar soil maturity is an important indicator to describe the degree of the space weathering. Using hyperspectral data to produce the submicroscopic metallic iron (SMFe) and to obtain lunar maturity is an important method for studying the space weathering. Since the in situ detection data is not disturbed, the results obtained are relatively more accurate and reliable. Therefore, the Chang'e-4 (CE-4) Yutu-2 rover was equipped with a detection instrument that directly obtained the in situ hyperspectral data (450-2395 nm) of the lunar surface, which provided a good opportunity for studying the lunar weathering. Two spectral data near the landing site of the CE-4 lander were selected, using the Hapke model and the spectral angle matching method, SMFe content was produced. The maturity of the lunar soil near the landing site of the CE-4 was further inferred based on the Morris model and FeO content. The results show that the lunar soil's maturity is 11.5, indicating that it may be immature lunar soil.
2020, 49(5): 20190463.
doi: 10.3788/IRLA20190463
The dual resolution camera combines large field of view and high resolution. The coaxial optical fixed structure avoids many problems caused by the moving parts of the zoom lens, and has potential application value in deep space detection target tracking and smart terminals such as mobile phones. The existing dual resolution image zoom algorithm based on deep learning has slow speed, no increase in information, poor adaptability of image network structure and forgery of image information restoration. To join a solution in normal image algorithm based on depth information was tentatively proposed in this paper. The feasibility of using image focus sharpness as depth information into the dual resolution zoom algorithm was demonstrated, the accuracy and effect of focus depth information detection was explored by Laplace image evaluation, and the dual resolution zoom algorithm of deep learning and traditional methods based on depth information was tested. The new excellent zoom algorithm used the space during normal focus of the camera which did not affect the imaging speed of normal images. The algorithm complexity is reduced by 60%, the computational memory overhead is reduced by 35%. The spatial relationship super-resolution information is more realistic and reliable, and the image result evaluation is improved by 10% to 50%.
2020, 49(5): 20190467.
doi: 10.3788/IRLA20190467
In Lunar Laser Ranging (LLR), higher repetition rate is an important trend for development, which is also of great significance for acquiring more LLR data. Based on the previous 10 Hz ranging rate system, a 100 Hz lunar ranging system with common-optical-path structure was developed by Yunnan Observatories, CAS. However, overlapping of the transmitting/echo signals exists in such a common-optical-path system, and seriously disturbs echo-photon detection. In the paper, the overlapping phenomenon was analyzed from the perspective of time sequence, and the correlation between the overlapping and the Time of Flight (TOF) was studied. Overlapping in the system was simulated with the orbital prediction of a lunar retro-reflector of a certain day, and the general overlapping ratio was approximately 8% for the observational duration. Sectional simulation based on each transmitting epoch was also performed, its result was consistent with the previous one. The method of avoiding overlapping by slightly adjusting rotating-mirror's speed was analyzed, and corresponding experiment was carried out, as proper speed adjustment turned out to be a solution when the overlapping happened.
2020, 49(5): 20190471.
doi: 10.3788/IRLA20190471
In the deep space exploration, the signal is delayed by the troposphere and a certain delay will occur at the receiver end, which affects the detection accuracy. The existing methods mainly realize the delay prediction by the grid model and the space model, but the accuracy of the model is limited due to the regional difference, and the prediction accuracy still has room for improvement. In this paper, a deep-space tropospheric delay prediction model based on adaptive multiple-input multiple-output (MIMO) signals was proposed. The satellite signal MIMO transmission mode was simulated based on a single transceiver antenna, and then an adaptive Kalman filter was constructed. The optimal transmission path was selected by adaptively adjusting the weight coefficient of the MIMO signal component to predict the tropospheric delay. The number of satellites participating in the measurement was four. Experiments were carried out under different signal-to-noise ratios and changing the number of MIMO channels to study the accuracy and actual measurement error of the adaptive MIMO model. The experimental results show that the prediction accuracy of the new method is much higher than that of the GPT2 model, GPT2w model and the commonly used UNB3 model and EGNOS model in real-time navigation and positioning.
2020, 49(5): 20190555.
doi: 10.3788/IRLA20190555
In order to analyze the reasons for star sensor performance degradation and the decrease of attitude measurement accuracy, performance degradation mechanisms of star sensor caused by Complementary Metal Oxide Semiconductor (CMOS) image sensor radiation damage were mainly studied. By establishing the correlation among the spatial radiation, radiation sensitive parameters of CMOS image sensor and the performance parameters of star sensor, the transmission mechanism from CMOS image sensor device parameters degradation to star sensor system parameters degradation was revealed. The 60Co-γ irradiation test showed that the decrease of signal-to-noise ratio led to the decrease of star sensor detection sensitivity after irradiation, and the signal-to-noise ratio was the bridge between the CMOS image sensor and the star sensor system. The proton irradiation test showed that when the irradiation fluence was more than 3.68×1010 p/cm2, the star point centroid could not be extracted correctly. The results lay a certain foundation for the research of star sensor attitude measurement error and correction technology, and also provide some theoretical basis for the design of high-precision star sensor.
2020, 49(5): 20201001.
doi: 10.3788/IRLA20201001
Deep space exploration refers to the exploration of the moon and the celestial bodies or space environment beyond the moon. The field of deep space exploration is an important part in implement strategy of space power, and is also one of the signature field of the spaceflight. This paper summarizes the development of deep space explorations in the past 60 years, highlights the achievements and future development trends of deep space exploration in China. According to Chinese Lunar Exploration Program(CLEP) and the first Mars exploration missions, the key technical breakthrough in these task were analyzed. Breakthrough, focusing on the follow-up mission planning of lunar and deep space exploration, discussed the key technologies of missions such as the establishment of lunar research station, asteroid exploration, Mars sampling return and Jupiter system exploration. On this basis, it summarizes the development route of China's deep space exploration technology and the key technologies that need to be studied and overcome in the future.
2020, 49(5): 20201002.
doi: 10.3788/IRLA20201002
Optical technology is widely applied in the China Lunar Exploration Program (CLEP) and the first China Martian exploration project: More than half of the scientific payloads were optical remote-sensing payload, and it was also widely used in the engineering areas including autonomous navigation, TT&C, monitoring, rendezvous and docking. In this paper, accomplished CLEP missions, on-going Chinese lunar and Martian projects and especially main achievements of optical technology applications were overviewed. Roadmap on China's future lunar, mars, jupiter and asteroids exploration was introduced. Development trends and prospects of optical technology in lunar and deep space exploration were analyzed and proposed.
2020, 49(5): 20201003.
doi: 10.3788/IRLA20201003
Deep space optical communication is the main technical approach of high speed data transmission to meet the future deep space exploration, and the main technical direction for the China Deep Space TT&C Network development. Especially with the development of intelligent and networked space communication system, the intelligent space communication network combining RF and optical communication will become the core facilities to support future deep space exploration missions. This paper combines China future lunar and deep space exploration development plan, based on the mission support capability of China Deep Space TT&C Network, the requirements of future deep space optical communication are sorted out. On the basis of learning from the latest research results, this paper analyzes the technical approach of constructing the earth terminal of deep space optical communication system. Based on the actual situation of China, this paper puts forward the development idea of constructing the mixed deep space optical communication ground system with space relay terminal and earth terminal, and finally forming the cognitive network of deep space optical communication.
2020, 49(5): 20201004.
doi: 10.3788/IRLA20201004
Optical sensor is the key component of the navigation guidance and control system in the deep space exploration mission, and it provides direction and location for stable operation of the spacecraft and scientific detection of the payload. The typical products of attitude sensor, autonomous navigation optical sensor, landing and obstacle avoidance optical sensor, patrol detection optical sensor were reviewed, and the key technology and development tendency were discussed.
2020, 49(5): 20201005.
doi: 10.3788.IRLA20201005
Spectral imaging technology is an important technical means in the field of deep space exploration and can serve a variety of space scientific experiments. Aiming at the demand of high stability and high light utilization of spectral loads in the field of deep space exploration, a new deep space hyperspectral diffraction computational imaging detection technology was proposed . Combining diffraction spectrum imaging technology and light field imaging technology to solve the problem of large-scale scanning of the detector in the diffraction spectrum push-broom imaging system, and one shot was realized to obtain the target spatial information and spectral information, that is, snapshot imaging. This has guiding significance for the design and research of deep space exploration hyperspectral imagers.
2020, 49(5): 20201006.
doi: 10.3788/IRLA20201006
Exploring the chemical composition of materials on the surface of the moon and planets is the key to research its origin and evolution history. Spectral detection technology is the major methods of material composition recognition and quantitative inversion. In-Situ spectral detection is different from remote sensing and sampling return detection, it refers to the short distance spectral detection performed at the target site. The lunar science research and resource exploration of "Chang'e-3 "mission need to implement the first In-Situ spectral detection technology on the lunar surface, by breaking through the key technologies of the new acousto-optic spectroscopic detection of staring time series scanning, we have developed high-performance, light and small, highly reliable instruments, adapted to the harsh surface environment, and become the first in the world to realize In-Situ spectral detection and analysis on the lunar surface of the moon. The paper takes "Chang'e-3 and 4" as typical applications, and introduces the In-Situ spectral detection technology of the lunar surface, including detection mechanism, working mode and the function, performance and application of the instrument; Finally, the "Chang'e-5" lunar mineral spectrometer was introduced which will be applied soon.
2020, 49(5): 20201007.
doi: 10.3788/IRLA20201007
The pace of human exploration of the universe has never stopped. To go further is the unremitting pursuit. As early as 1969, the ''Apollo ''11 spacecraft of the United States realized the first landing of human beings on the moon, and then another five spacecraft successfully landed on the moon. In recent years, China's "Chang'e" project as a representative of the successful implementation of the unmanned lunar exploration program, making the lunar exploration once again by the world's attention. In the context of the continuous development of space exploration, manned moon landing will be on the stage again at some time in the future. The important processes of landing on the moon, lunar surface activity, take-off and ascent are all inseparable from the control technology. After introducing the early manned landing on the moon and the achievements of lunar exploration in recent years, this paper analyze the concept of the future manned landing mission in China, discusses the crucial control technology, and puts forward several development prospects.
2020, 49(5): 20201008.
doi: 10.3788/IRLA20201008
In orbit capturing and real-time monitoring the status of distant dimmer space targets is of vital importance for space safety. However, when the sensitivity approaches 14 magnitude, the intensive stellar population, the stellar scattering light will reduce the detection efficiency greatly, resulting in a limited detection range and ability. To solve this problem, a simple method for space object capturing, classification and online tracking was presented, synchronously eliminating the dense background stars and sequentially extracting the possible space targets, utilizing the regular motion of a moving object in a short timespan. Ground simulations and tests validate the effectiveness and accuracy of the method. It seems that this method can also be used as a basic function for deep space projects, such as asteroid and planet exploration in the solar system.
2020, 49(5): 20201009.
doi: 10.3788/IRLA20201009
Autonomous optical navigation is a key technology for asteroid exploration missions. Terrain relative navigation methods based on optical images have been successfully applied in previous asteroid exploration missions. Optical navigation uses features such as the asteroid's surface topography and albedo to accurately establish reference datums and navigation landmarks, and give precise relative positions, attitudes, and velocities during descent based on the matching results of real-time observation images. The development of optical navigation technology for asteroid probe descent and landing was reviewed, and its key technologies and development trends were summarized, which provided a reference for China's asteroid exploration mission.
