May 2022, Volume 5 Issue 1
    

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  • Analysis About Landing Site Selection and Prospective Scientific Objectives of the Von Kármán Crater in Moon Farside
    MENG Zhiguo, LI Cui, PING Jinsong, HUANG Qian, CAI Zhanchuan, Alexander Gusev
    2018, 5(1): 3-11. https://doi.org/10.15982/j.issn.2095-7777.2018.01.001
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    The Von Kármán crater，inside the South Pole-Aitken basin on the lunar farside，is initially selected as the landing area for Chinese Chang’E-4 mission. The in-situ exploration in the crater will reveal some essential problems about the formation and evolution of the Moon，which will be of great significance in the current Moon research. The geologic significances and scientific values of the Von Kármán crater are summarized. Thereafter，the distributions of topography，composition，deep structure，and temperature brightness of the Von Kármán crater are analyzed with LRO satellite LOLA data，Clementine UV-VIS data，GRAIL data，and Chang’E-2 CELMS data and their scientific meanings are also presented. Finally，combined with our results and the previous prospects about theVon Kármán crater，three candidate landing sites and the possible scientific discoveries are proposed.
  • Research on Solar Radiation of Von Kármán Crater Using LOLA Data
    ZHANG Jidong, MENG Zhiguo, ZHU Yunzhe, ZENG Zhaofa, PING Jinsong
    2018, 5(1): 12-19. https://doi.org/10.15982/j.issn.2095-7777.2018.01.002
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    The Von Kármán crater is one of the candidate landing sites of Chinese CE-4 mission. An effective solar radiation model was established through the improvement of the lunar illumination model based on LOLA data. Then the solar radiation condition of Von Kármán crater in 2018 was numerically simulated and analyzed. The results are as followings. Firstly，the topography strongly impacts the solar radiation，that is，there is more solar radiation in the south crater wall，the north side of the central peak and the south wall of the small craters. What’s more，the solar radiation energy received by the most areas of bottom plain is about （0.9~1）×1010 J/m2. Also，the solar radiation is more easily affected by latitude without considering the surface slope，the range of which is between 0.87 to 1.01×1010 J/m2 from the north end to the south. Thereafter，two candidate landing areas，named regions S1 and S2，were proposed based on surface slope and illumination conditions. The Region S1 is located in the bottom of the southern plain with more flat terrain，sunrise earlier and longer illumination time；while the Region S2 is located in the northwest side of the central peak with more solar radiation energy. The annual average solar radiation energy of the two regions are 9.31×109 J/m2 and 9.65×109 J/m2，respectively. The longest illumination time is in July，which is more suitable for landing.
  • Microwave Emission Features of Von Kármán Crater Revealed by Chang’E-2 CELMS Data
    HU Shuo, MENG Zhiguo, ZHU Yunzhe, LIAN Yi, LI Cui, GUSEV Alexander
    2018, 5(1): 20-26. https://doi.org/10.15982/j.issn.2095-7777.2018.01.003
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    Von Kármán crater is located in the northwest of the SPA basin on the far side of the Moon. The crater cuts through the shallow crust and has abnormal distribution in mineral composition. Therefore，the study on the microwave emission features of Von Kármán crater will be of great significance for the thermal evolution and magma evolution of the moon. Based on the microwave sounder（CELMS）data from Chang’e-2，the brightness temperature（TB）maps and TB difference（dTB）maps are generated using the time angle analysis and the bilinear interpolation method. Then the microwave radiation characteristics of Von Kármán crater are studied combined with previous geologic results and the composition map via the ArcGIS software. The discoveries are as followings：（1）a high TB anomaly is found in the north of the crater basin，preliminarily identified as high substrate temperature；（2）the TB shows a good correlation with the（FeO+TiO2）content in the south part of the crater basin；（3）according to the TB behaviors of the Von Kármán crater，new geological units are zoned in the crater floor;（4）according to the TB performances of the Von Kármán crater，high priority of the candidate landing areas should be given to the north part with TB anomaly，followed by the south and west parts.
  • The Research of Temporal and Spatial Distribution of Microwave Brightness Temperature in Chang’E-4 Landing Area Based on Field Theory
    LIAN Yi, HE Long, MENG Zhiguo, PING Jingsong, HU Shuo, ZENG Xiaoming
    2018, 5(1): 27-33. https://doi.org/10.15982/j.issn.2095-7777.2018.01.004
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    Chang’e-4 (CE-4) probe will achieve the first soft landing on the farside of the moon in the history of mankind, and the landing zone is tentatively fixed in the Von Karman impact crater which is in the South Pole-Aitken basin. In view of the lack of field analysis of microwave radiation brightness temperature, analyzed the brightness temperature’s temporal and spatial distribution characteristics of Von Karman impact crater was analyzed based on the field and the penetrability of Chang’e Microwave radiometer. The results show that there is a significant couple mode between 3GHz diurnal brightness temperature field and 37GHz diurnal brightness temperature field, ,and the trend of brightness temperature appeared consistent in the crater. It also turns out that the area with high FeO+TiO2 (FTA) content has a higher relativity , which is the key area of brightness temperature change. Nevertheless, the FTA content does not have significant impact on the density of contours. Contrarily, the density of contours is mainly influenced by the roughness of the moon’s surface. Finally, the research provided a reference for the choice of landing zone of CE-4 probe by analyzing the temporal and spatial distribution characteristics of brightness temperature, stratigraphic unit, chemical constituents of substance and other factors in Von Karman impact crater.
  • A Hidden Lunar Mascon Under the South Part of Von Kármán Crater
    PING Jinsong, HUANG Qian, YAN Jianguo, MENG Zhiguo, WANG Mingyuan
    2018, 5(1): 34-40. https://doi.org/10.15982/j.issn.2095-7777.2018.01.005
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    At a candidate area of lunar landing mission，a mascon anomaly may indicate historical complicated evolution of dynamics，and fruitful material composition. The lunar mascon distribution is usually obtained by means of satellite gravity method. The obtained gravity field information combined with the lunar topography information both from CE-1 lunar orbital mission show that a middle scale mason is just under the south half part of the Von Kármán Crater. This means that Von Kármán Crater is a younger crater following the older one. The discovery of this hidden middle scale mascon will benefit the study of lunar evolution，and also benefit the exploration of Von Kármán Crater in future Chang’E mission.
  • Crustal and Subsurface Structures of Chang’E-4 Lunar Farside Landing-Site
    HUANG Qian, WANG Taimao, ZHAO Jiannan, MENG Zhiguo
    2018, 5(1): 41-49. https://doi.org/10.15982/j.issn.2095-7777.2018.01.006
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    As the selected landing-site for Chinese Chang’e-4 mission, the Von Kármán crater, located in the central region of the South Pole-Aitken (SPA) basin, opens an important window to study the lunar farside crust. In this paper, the newly obtained gravity, topography, Bouguer gravity/gradient and crustal thickness data are used to comprehensively study the crustal and subsurface structures of the Von Kármán crater. Results show that the Von Kármán crater is located in the northern part of a pre-existed impact crater Von Kármán M, which has obvious central positive Bouguer gravity anomaly and linear Bouguer gravity gradient features, indicating possible dikes and dense materials beneath the crater. The Von Kármán crater is likely to penetrate through the entire crust of the SPA and excavated the deep mantle materials. The crustal thickness map shows that the southern crust of the Von Kármán crater is as thin as 5km and the northern area has an average crust thickness between 15 and 20km. The bulk density of the Von Kármán crater is 2630kg·m–3, which is about 100kg·m–3 higher than that of the farside highland crust. The grain density of this region is 2890kg·m–3, suggesting an average porosity of 9%, which is slightly lower than that of the lunar crust.
  • Topography Analysis of the Von Kármán Crater Based on the Observed Images
    ZHENG Chen, YAO Hongtai
    2018, 5(1): 50-56. https://doi.org/10.15982/j.issn.2095-7777.2018.01.007
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    The Von Kármán crater，located in the South Pole-Aitken basin on the lunar far-side，is initially selected as the landing area for the Chang’e-4 mission，and its topography analysis is an important part of the mission design. In this paper，a Markov random field model（MRF）is employed to analyze the elevation data of the Lunar Orbiter Laser Altimeter（LOLA）and the image data of the Lunar Reconnaissance Orbiter Camera（LROC），which is developed to capture the topography of Von Kármán crater from the perspective of clustering. The likelihood function of the MRF model is used to describe the observed data with approximate normal distribution，and the label random field is designed to model the spatial relationship between data，and the probability inference is finally employed to obtain the clustering result. Experimental results show that clustering can effectively illustrate the topography at some low-contrast regions，and they can also assist the overall and local topography analysis by setting different clustering numbers.
  • Topography Characteristics Analysis of Von Kármán Crater Using LOLA Data
    WANG Huihui, MENG Zhiguo, LI Cui, ZHU Yunzhe, CAI Zhanchuan, LI Xiangyue
    2018, 5(1): 57-65. https://doi.org/10.15982/j.issn.2095-7777.2018.01.008
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    Von Kármán crater, located in the northwest of SPA, is the candidate landing site for Chang’e-4. In this paper, LOLA (onboard LRO satellite) data are processed by the maximum mean method, the root mean square height method and the box counting method respectively to acquire and analyze the slope, roughness and fractal dimension information of Von Kármán crater. The results show that the elevation of Von Kármán crater is low and the most-south area has the lowest elevation and the rest areas have respectively higher elevation. There are many impact structures in Von Kármán crater. The mean slope of Von Kármán basin is 1.3° and there are about 85% areas having the slope less 2°. There are 95.1% areas having roughness of less than 20m and the FD (Fractal Dimension) of the whole Von Kármán basin is high. All of these show that Von Kármán basin has smooth topography and stable structure. The statistical results hint that the south, southeast, and northeast parts of Von Kármán basin have lower slope, lower roughness and higher FD, which makes the basin is appropriate for the Chang’e-4’s landing. What’s more, the comparative analysis presents that the topography condition in Von Kármán basin is better than that in Chang’e-3 landing area.
  • Compositional Studies of the Von Kármán Crater
    ZHANG Xunyu, XU Tianyi, LI Cui
    2018, 5(1): 66-70. https://doi.org/10.15982/j.issn.2095-7777.2018.01.009
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    Chang’e-4 mission is expected to land within the Von Kármán crater on the lunar far side and provides an opportunity to in situ study the South Pole-Aitken basin which is the largest and oldest recognized impact basin on the Moon. Chemical compounds （TiO2 and FeO） and mineralogical composition of the Von Kármán crater are analyzed based on several spectral data, which aims to provide more technical support for the future exploration in the Chang’e-4 mission. The Von Kármán crater is TiO2-pool （about 1.5~2.5 wt%）, FeO-rich （about 12~16 wt%）, and infilled by low-Ti basalts. The materials outside the crater are dominated by noritic materials （Low-Ca pyroxene） with abundance of TiO2（~1 wt%）and FeO（~10 wt%）. In addition, some plagioclase-rich layers are also exposed on the southern region outside the Von Kármán crater.
  • A Survey on Teleoperation of Canada’s Mobile Servicing System
    GUO Xiangyan, LIU Chuankai, WANG Xiaoxue
    2018, 5(1): 78-84. https://doi.org/10.15982/j.issn.2095-7777.2018.01.011
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    The system design and safety issues associated with the ground teleoperation of Canada’s Mobile Servicing System(MSS) are described in this paper. Firstly, the system configuration of MSS is presented, and the needs for MSS ground teleoperation are analyzed. Then, the challenges of operating the MSS from ground and the related operational techniques developed are discussed,and the mission planning and mission execution as well as on-orbit demonstration are overviewed in the MSS ground control operations. Finally, the suggestions are given for China’s space station manipulator teleoperation , providing a reference for the development of space robot teleoperation
  • On Chip Digital Sun Sensor Based on SiP Technology
    WU Di, CHEN Shu, CHEN Longjiang, YE Zhilong, ZHENG Xunjiang
    2018, 5(1): 85-89. https://doi.org/10.15982/j.issn.2095-7777.2018.01.012
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    A new type of digital sun sensor is introduced which is designed by SiP technology. Filters are installed on the image sensors. By using the proposed design, the mass and volume of the sun sensors, are decreased, while the reliability is increased. In deep space, the digital sun sensor captures solar position and protects the other optics sensor from sunshine. Calibration has been done and sun spot is captured by the experimental prototype.
  • Establishment of a Navigation Star Database Based on Star Distribution
    YE Zhilong, SUN Shuodong, CHEN Shu, WU Di, WU Bin
    2018, 5(1): 90-96. https://doi.org/10.15982/j.issn.2095-7777.2018.01.013
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    In order to further improve attitude precision of star sensors, the influence of star spatial geometric distribution to attitude precision is analyzed and a method of establishing a navigation star database based on star distribution is proposed. On the basis of analyzing the current star database, Hipparcos is selected as the basic star database, while, dark-star and double-star are deleted in the star database, and then star spatial geometric distribution in every FOV (Field of View) is analyzed and compared while traversing all-sky, three stars which determine the worst attitude precision are deleted. Finally, Traversing compensationof star database is executed to ensure the uniformity of star distribution. The experimental results show that all-sky recognition rate is 100% by using the star database made by the proposed method in all celestial orbit tests, and the areas with more than 10 stars distribution r account for 97.64%. The porposed method is of good coverage, and can effectively improve the attitude accuracy.