Jul 2022, Volume 9 Issue 3
    

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  • Reviews
    The Solar Wind and Particle Radiation Environment on the Surface of the Moon—New Observations from Chang’E-4
    WANG Chi, LI Lei, ZHANG Aibing, ZHANG Shenyi, HOU Donghui, XU Zigong, XIE Lianghai, WANG Huizi, LUO Pengwei, GUO Jingnan, SHI Quanqi, ZHANG Xiaoping
    2022, 9(3): 239-249. https://doi.org/10.15982/j.issn.2096-9287.2022.20220020
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    The solar wind, solar energetic particles and the galactic cosmic rays can reach the Moon almost unhindered, and interact with the lunar surface. The solar wind is partly scattered by the lunar regolith as hydrogen energetic neutral atoms, and the solar wind can also sputter heavy energetic neutral atoms out of the lunar regolith as well. While the albedo radiation, resulting from impact of the solar energetic particles and the galactic cosmic rays on the lunar regolith, are mainly composed of neutrons and gamma rays, features of the lunar surface radiation environment. The first ever in situ measurements of energetic neutral atoms and particle radiation have been carried out by Chang’E-4 on the lunar farside. Results reveal that a mini-magnetosphere is formed in the vicinity of the Moon, suggesting ENA is a new perspective to study the solar wind - Moon interaction. While the radiation measurements provide valuable information to guarantee the health of future robotic or manned missions to the Moon.
  • Topic：Moon-based Earth Observation
    Research Status and Prospect of Moon-Based Earth Observation: A Review
    GUO Huadong, DING Yixing, LIU Guang
    2022, 9(3): 250-260. https://doi.org/10.15982/j.issn.2096-9287.2022.20210080
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    The deployment of remote sensing sensors on the Moon can realize long-term, overall and stable Earth observation and improve the observation ability of the existing system. In particular, from the outside of the Earth system, the Moon-based remote sensors can observe the evolution process of the earth system and the interaction and influence between the earth system and its exterior. This paper discusses the research progress of Moon-based earth observation in detail from four aspects: scientific objectives, sensor technology, parameter simulation and estimation methods and observatory location. The key scientific problems are analyzed, and a series of new models and methods are summarized. At the end of this paper, some suggestions for the development of Moon-based Earth observation are put forward.
  • Topic：Moon-based Earth Observation
    Research on Spatio-Temporal Characteristics of Moon-Based SAR Earth Observation
    CHEN Guoqiang, GUO Huadong, LIANG Da, DING Yixing, LV Mingyang, LIU Guang
    2022, 9(3): 261-268. https://doi.org/10.15982/j.issn.2096-9287.2022.20210076
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    With the rapid development of lunar exploration, the concept of moon-based observation of earth has received more and more attention. The synthetic aperture radar (SAR) deployed on the moon for earth observation can obtain continuous observations of large areas on earth surface, and realize a single wide-area observation mode which makes up for the deficiency of space-borne SAR. Based on the JPL ephemeris data, in this paper the observation difference of moon-based SAR in different scenarios such as time domain and space domain was analyzed, and the simulation of SAR echo was completed using the actual earth-moon spatial relationship. The results show that the moon-based SAR can always find the intersection line of zero Doppler plane on earth surface, and long-term, large-scale periodic observations can be achieved. The SAR echo simulation verifies its feasibility. The study of moon-based SAR observations can provide a basis for follow-up studies such as surface tidal movement and polar sea ice rebound.
  • Topic：Moon-based Earth Observation
    Simulation and Application of Moon-Based Earth Observation Image
    DENG Yu, GUO Huadong, LIU Guang, YE Hanlin, HUANG Jing
    2022, 9(3): 269-277. https://doi.org/10.15982/j.issn.2096-9287.2022.20210073
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    To solve the problem that the existing simulation system only qualitatively describes the Moon-based observation image, an image simulation method based on rigorous imaging model for Moon-based platform was proposed, and the quantitative relationship between image point and object point was established. The method was applied to the simulation of observation geometric image and radiation energy image. Based on long-time series simulation results, the effect of lunar orbit on geometric images and radiation energy images was further analyzed and summarized. The results show that this image simulation method based on the rigorous imaging model is feasible, and accurately expresses the image characteristics that vary with the characteristics of the lunar orbit. This method lays a foundation for the application of Moon-based observation images, and has great significance for the subsequent parameter design of different types of Moon-based sensors.
  • Topic：Moon-based Earth Observation
    Geometric Simulation of Earth’s Outgoing Radiation Viewed from a Moon-Based Platform
    HUANG Jing, GUO Huadong, LIU Guang, DENG Yu
    2022, 9(3): 278-284. https://doi.org/10.15982/j.issn.2096-9287.2022.20210078
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    Due to the characteristics of integrity, multi-angle and long period, a Moon-based platform is expected to accurately estimate Earth outgoing radiation. To evaluate this platform’s capabilities, this paper established a one-to-one mapping algorithm based on the geometric relationship and used the Goddard Earth Observing System model version 5 (GEOS-5) data as model input to simulate Earth’s outgoing radiation viewed from a Moon-based platform, so as to learn about the regularity of Earth outgoing radiation viewed from the Moon-based platform. Results show that a Moon-based platform can cover about 178° both in latitudinal and longitudinal direction in one image, including the polar regions. The changing inclination of the orbit of the Moon gives a better observation condition for high latitude regions, and the viewing zenith angle in polar regions can reach to 60°. These results indicate the simulation method can effectively support the observation of Earth’s outgoing radiation observation and lay the foundation for future research.
  • Topic：Moon-based Earth Observation
    Characteristics Analysis of Moon-Based Monitoring of Earth’s Outgoing Radiation at the Top of Atmosphere
    YE Hanlin, DENG Yu, LIU Guang, GUO Huadong
    2022, 9(3): 285-291. https://doi.org/10.15982/j.issn.2096-9287.2022.20210074
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    Due to the uncertainty of parameter design of the Moon-based radiometer, the characteristics of Moon-based Earth’s outgoing radiation at the top of the atmosphere were investigated. Based on the single-point observation geometry for a Moon-based platform, this paper analyzed observational characteristics and data of different Moon-based platforms’ positions on the lunar surface, and the observational sampling characteristics. The results indicate that the orbit of the Moon is with variable orbital inclination and variant observation distances from the Earth, and equipping a radiometer on the lunar surface can sample the whole Earth’s surface within one orbital period. In addition, the suggested dynamic range is from 5.50×10?2 to 8.50×10?2 W/m2, its temporal sampling interval is no more than 4 hours, and the accumulative sampling period is one orbital period (27.3 days). The above results provide an important basis for the design of the Moon-based radiometer.
  • Topic：Moon-based Earth Observation
    Potential Moon-Based Platform Sites of Lunar South Polar Regions
    ZHANG Jidong, LI Xiangyue, PING Jinsong
    2022, 9(3): 292-299. https://doi.org/10.15982/j.issn.2096-9287.2022.20210079
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    To select a suitable location for a Moon-based platform in the lunar south polar regions, the surface illumination, the Earth observation conditions and the slope are schosen as the main factors , which shows the solar energy and thermal environment on the lunar surface, the ability to obtain scientific data, and difficulty of construction. Based on the topography data and the orbit data of the Sun, the Earth and the Moon, an integrated solar illumination and Earth observation geometric model is established and applied to study seven key areas (M1 ~ M7). The lunar surface positions with the illumination rate greater than 80% and the Earth observation rate greater than 30% are taken as the primary selection area of the Moon-based platform, next, their slope conditions are analyzed and a grading evaluation is carried out. Combined with the characteristics of each primary selected area, three lunar positions with higher optimization level are finally recommended, which are located at the eastern edge of De Gerlache crater (in M1), the mountaintop where Sverdrup crater connects with Shackleton crater (in M4), and the mountaintop between the Shackleton crater and the Slater crater (in M7), and these results will provide reference for the follow-up lunar south polar exploration missions.
  • Topic：Mapping technique of extraterrestrial planets
    Recent Advances and Prospects in Extraterrestrial Planets Mapping
    XU Qing, GENG Xun
    2022, 9(3): 300-310. https://doi.org/10.15982/j.issn.2096-9287.2022.20210162
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    The topographic mapping of extraterrestrial planets provide basic geospatial data for engineering missions and various planetary scientific research, which can be used to select landing sites, plan path of rovers and conduct planetary geological and geomorphological analysis. We summarize the representative topographic mapping techniques and products in the exploration missions of moon, Mars and asteroids. This paper focuses on the research status of the techniques of generating digital orthophoto map and digital elevation model using mapping camera and LiDAR. We also give some suggestions on standard setting, data sharing, key technical bottlenecks and data processing technology system of extraterrestrial planets mapping.
  • Topic：Mapping technique of extraterrestrial planets
    A Low-resolution Slope Compensation Method Involving Slope Change Rate
    YIN Li, YE Lejia, DI Kaichang, LIU Bin, SUN Xiaozhu, WANG Changhuan, BO Zheng
    2022, 9(3): 311-320. https://doi.org/10.15982/j.issn.2096-9287.2022.20210161
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    To solve the problem of slope reduction caused by the lack of high-resolution Digital Elevation Model ( DEM ) on the surface of moon, Mars and other planets, we propose a low-resolution slope compensation method involving slope change rate factors. It is an improvement on the existing linear compensation method by incorporating slope change rate into the compensation model to obtain better accuracy for slope compensation. In this paper, lunar and Martian data are used to verify the method. Several lunar and Martian low-resolution DEMs covering a variety of terrains are selected and compensated using the improved method. Then they are validated using slopes generated from the high-resolution DEMs. The results show that after applying the proposed compensation function, the compensated slopes can represent the terrain features of the lunar and Martian surface better compared to the original low-resolution slopes. Meanwhile, the proposed method considering the slope change rate is more effective than the traditional linear compensation method. Based on the improved method, the overall and hierarchical compensation models suitable for various lunar landforms are established and the low-resolution Martian slope data covering 50 km×50 km of the Tianwen-1 landing site are compensated and analyzed.
  • Topic：Mapping technique of extraterrestrial planets
    Study on Morphological Characteristics and Genesis of Dome Around Chang’E-5 Sampling Point
    WU Wenhui, REN Xin, CHEN Yuan, Paliguli·JIEENSI , SUN Guoyang
    2022, 9(3): 321-328. https://doi.org/10.15982/j.issn.2096-9287.2022.20210068
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    Mons Rümker and Mairan volcanic dome structure are distributed around Chang’E-5 sampling point. At present, there is a lack of comparative research on their morphological characteristics, genesis and classification standards. Therefore, this paper compared the morphological characteristics and formation factors of the two types of domes through Chang’E image and topographic data, and discussed the division criteria of domes. In this study, 13 lunar mare domes of Mons Rümker and 4 non-mare domes of Mairan were delineated, and the magma rheological parameters during the formation of the domes were calculated. The results show that the Rümker lunar mare domes are relatively low and flat. According to the slope and height, the domes are divided into Rümker type I lunar mare dome (slope < 5 °, height 200-400 m) and Rümker type II mare dome (slope 5 °-7 °, height 300-600 m). Among them, the second kind of higher and steeper lunar sea dome has higher viscosity and lower eruption rate. Compared with the Rümker mare dome, the Mairan non-mare dome is higher and steeper, and its magma eruption rate is generally lower than that of mare domes, with high magma viscosity, poor fluidity and long eruption cycle. Spatially, the four non-lunar mare domes where Mairan is located are linearly distributed and their material composition and formation time are similar, indicating that they are likely to be related to each other.
  • Topic：Mapping technique of extraterrestrial planets
    Martian Landing Area Morphology Interpretation and Quantitative Analysis of the Zhurong Rover
    LIU Jia, LIU Bin, DI Kaichang, YUE Zongyu, YU Tianyi, WANG Jia, GOU Sheng
    2022, 9(3): 329-337. https://doi.org/10.15982/j.issn.2096-9287.2022.20210123
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    Tianwen-1 lander and rover successfully landed in the southern Utopia Planitia of Mars on May 15, 2021. As China's first Mars exploration mission, Tianwen-1 achieved orbiting, landing and patrolling tasks in one mission. In this paper, we apply the photogrammetry methods to produce mapping products from high-resolution orbiter remote sensing images, and to analyze the landing area environment. The environment of the landing area is not only important for the path planning and safe driving of the Mars rover, but also provides fundamental information for science research. Mainly focuses on the Tianwen-1 landing area (within the surrounding 20 km of the landing point), and utilizes the 5 m/pixel CTX DOM and Tianwen-1 DEM product data to quantitatively analysis the impact crater density, impact crater depth, depth-to-diameter ratio, etc. Further interpretation and analysis of the geomorphic feature and geological background of the landing area are conducted. The results show that there are many small craters, transverse aeolian ridge, pitted cones, structural ridges and throughs in the region, most of the impact craters on the surface of the landing area are secondary craters or degraded impact craters, with an aspect ratio between 0.001 to 0.136. In addition to in-depth analysis of the geological and geomorphological features of the landing area, the crater statistics and geomorphic feature analysis are valuable for geological evolution study of the Utopia Planitia.
  • Topic：Mapping technique of extraterrestrial planets
    Topography Modeling, Mapping and Analysis of China’s First Mars Mission Tianwen-1 Landing Area from Remote Sensing Images
    LIU Sicong, TONG Xiaohua, LIU Shijie, XIE Huan, ZHAO Hui, LIU Dayong, XU Xiong, YE Zhen, WANG Chao, LIU Xianglei
    2022, 9(3): 338-347. https://doi.org/10.15982/j.issn.2096-9287.2022.20220005
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    By using multi-source remote sensing image data from Mars Orbiters, the technical framework for Martian surface topography fine 3D modeling and automatic classification was developed. The high-resolution terrain of Tianwen-1 landing area was made by combining the photogrammetry and the Shape-from-Shading (SFS) methods, and high-resolution images were used to classify and analyze the topography category and distribution of the land area using a deep convolution neural network. The profile analysis results show that the high-precision terrain data presented in this paper are highly consistent with high resolution digital elevation model (DEM) products published by China and US, resulting in the mean elevation errors equal to 1.866 m and 1.074 m, respectively. Furthermore, it can be seen from the comprehensive terrain and morphology analysis by using the orbiter remote sensing images that near the landing point the slope is less than 3° and the fluctuation of the surface is less than 30 cm. This indicates that the overall terrain of Tianwen-1 landing area is flat and the morphology category is relatively single, which meets the requirements of the probe’s safe landing. The terrain produced by Tianwen-1 high-resolution camera data and classification results, which can be effectively applied to the morphological analysis of the landing and patrol areas, when combined with multi-source Mars remote sensing data such as HiRISE, can provide important basic data and reference information for subsequent scientific explorations of Zhurong patrol.
  • Topic：Mapping technique of extraterrestrial planets
    A Fast Photogrammetric Processing Method for Linear Pushbroom Planetary Remote Sensing Images
    GENG Xun, XU Qing
    2022, 9(3): 348-356. https://doi.org/10.15982/j.issn.2096-9287.2022.20210002
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    Planetary photogrammetry is widely used to derive the mapping products of extraterrestrial planets. However, the existing planetary photogrammetric methods exhibit low efficiency and poor applicability for long strip linear pushbroom planetary images. We developed photogrammetric processing method as well as corresponding software modules for linear pushbroom planetary images based on fast geometric rectification. Based on the rigorous sensor model of linear pushbroom planetary images, the fast back projection algorithm is used for orthophotos rectification, and multi-threaded programming technique is also used to further improve the computational efficiency. To derive control network for linear pushbroom planetary images with large amount of data, we first conduct image matching on approximate orthophotos that derived from fast geometric rectification to acquire tie points, and then convert the matched tie points into original image space using rigorous sensor model. Experiments were conducted using Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC) and Mars Express (MEX) Hight Resolution Stereo Camera (HRSC) images, and the corresponding DOMs and DEMs were derived. Compared with the planetary image processing software USGS ISIS, the developed method significantly improves the processing efficiency of linear pushbroom planetary images.