scholarly journals Chronology of the Basalt Units Surrounding Chang’e-4 Landing Area

2021 ◽  
Vol 14 (1) ◽  
pp. 49
Author(s):  
Zongyu Yue ◽  
Ke Shi ◽  
Gregory Michael ◽  
Kaichang Di ◽  
Sheng Gou ◽  
...  
Keyword(s):  
Lunar Surface ◽  
Measured Data ◽  
The Moon ◽  
Soft Landing ◽  
Size Frequency Distribution ◽  
Popular Method ◽  
Crater Size ◽  
Elevation Data ◽  
Geological Units

The Chang’e-4 (CE-4) lunar probe, the first soft landing spacecraft on the far side of the Moon, successfully landed in the Von Kármán crater on 3 January 2019. Geological studies of the landing area have been conducted and more intensive studies will be carried out with the in situ measured data. The chronological study of the maria basalt surrounding the CE-4 landing area is significant to the related studies. Currently, the crater size-frequency distribution (CSFD) technique is the most popular method to derive absolute model ages (AMAs) of geological units where no returned sample is available, and it has been widely used in dating maria basalt on the lunar surface. In this research, we first make a mosaic with multi-orbital Chang’e-2 (CE-2) images as a base map. Coupled with the elevation data and FeO content, nine representative areas of basalt units surrounding the CE-4 landing area are outlined and their AMAs are derived. The dating results of the nine basalt units indicate that the basalts erupted from 3.42 to 2.28 Ga ago in this area, a period much longer than derived by previous studies. The derived chronology of the above basalt units establishes a foundation for geological analysis of the returned CE-4 data.

scholarly journals 2.2.2 The Size Frequency Distribution and Rate of Production of Microcraters

1976 ◽  
Vol 31 ◽  
pp. 227-231
Author(s):  
D. A. Morrison ◽  
E. Zinner
Keyword(s):  
Frequency Distribution ◽  
Lunar Surface ◽  
Particle Flux ◽  
Surface Orientation ◽  
Submicron Particle ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Crater Size ◽  
Size Frequency ◽  
Micron Diameter

AbstractCrater size frequency distributions vary to a degree which probably cannot be explained by variations in lunar surface orientation of the crater detectors or changes in micrometeoroid flux. Questions of sample representativity suggest that high ratios of small to large craters of micrometeoroids (e.g., a million 1.0 micron craters for each 500 micron crater) should be the most reliable. We obtain a flux for particles producing 0.1 micron diameter craters of approximately 300 per cm2 per steradian per year. We observe no anisotropy in the submicron particle flux between the plane of the ecliptic and the normal in the direction of lunar north. No change in flux over a 106 year period is indicated by our data.

scholarly journals Effect of Lunar Complex Illumination on In Situ Measurements Obtained Using Visible and Near-Infrared Imaging Spectrometer of Chang’E-4

2021 ◽  
Vol 13 (12) ◽  
pp. 2359
Author(s):  
Jiafei Xu ◽  
Meizhu Wang ◽  
Rong Wang ◽  
Qi Feng ◽  
Honglei Lin ◽  
...  
Keyword(s):  
Lunar Surface ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Specular Reflection ◽  
In Situ Measurements ◽  
The Moon ◽  
Spectral Measurements ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer

In-situ measurements of the spectral information on the lunar surface are of significance to study the geological evolution of the Moon. China’s Chang’E-4 (CE-4) Yutu-2 rover has conducted several in-situ spectral explorations on the Moon. The visible and near-infrared imaging spectrometer (VNIS) onboard the rover has acquired a series of in-situ spectra of the regolith at the landing site. In general, the mineralogical research of the lunar surface relies on the accuracy of the in-situ data. However, the spectral measurements of the Yutu-2 rover may be affected by shadows and stray illumination. In this study, we analyzed 106 CE-4 VNIS spectra acquired in the first 24 lunar days of the mission and noted that six of these spectra were affected by the shadows of the rover. Therefore, a method was established to correct the effects of the rover shadow on the spectral measurements. After shadow correction, the FeO content in the affected area is corrected to 14.46 wt.%, which was similar to the result calculated in the normal regolith. Furthermore, according to the visible images, certain areas of the explored sites were noted to be unusually bright. Considering the reflectance, geometric information, and shining patterns of the multi-layer insulation (MLI), we examined the influence of the specular reflection of the MLI on the bright spot regionsd , and found that the five sets of data were likely not affected by the specular reflection of the MLI. The results indicated that the complex illumination considerably influences the in situ spectral data. This study can provide a basis to analyze the VNIS scientific data and help enhance the accuracy of interpretation of the composition at CE-4 landing sites.

scholarly journals COMPUTER VISION IN THE TELEOPERATION OF THE YUTU-2 ROVER

2020 ◽  
Vol V-3-2020 ◽  
pp. 595-602
Author(s):  
J. Wang ◽  
J. Li ◽  
S. Wang ◽  
T. Yu ◽  
Z. Rong ◽  
...  
Keyword(s):  
Computer Vision ◽  
Path Planning ◽  
Lunar Surface ◽  
Control Method ◽  
Landing Site ◽  
Slope Aspect ◽  
Soft Landing ◽  
Landing Point ◽  
Lunar Farside

Abstract. On January 3, 2019, the Chang'e-4 (CE-4) probe successfully landed in the Von Kármán crater inside the South Pole-Aitken (SPA) basin. With the support of a relay communication satellite "Queqiao" launched in 2018 and located at the Earth-Moon L2 liberation point, the lander and the Yutu-2 rover carried out in-situ exploration and patrol surveys, respectively, and were able to make a series of important scientific discoveries. Owing to the complexity and unpredictability of the lunar surface, teleoperation has become the most important control method for the operation of the rover. Computer vision is an important technology to support the teleoperation of the rover. During the powered descent stage and lunar surface exploration, teleoperation based on computer vision can effectively overcome many technical challenges, such as fast positioning of the landing point, high-resolution seamless mapping of the landing site, localization of the rover in the complex environment on the lunar surface, terrain reconstruction, and path planning. All these processes helped achieve the first soft landing, roving, and in-situ exploration on the lunar farside. This paper presents a high-precision positioning technology and positioning results of the landing point based on multi-source data, including orbital images and CE-4 descent images. The method and its results have been successfully applied in an actual engineering mission for the first time in China, providing important support for the topographical analysis of the landing site and mission planning for subsequent teleoperations. After landing, a 0.03 m resolution DOM was generated using the descent images and was used as one of the base maps for the overall rover path planning. Before each movement, the Yutu-2 rover controlled its hazard avoidance cameras (Hazcam), navigation cameras (Navcam), and panoramic cameras (Pancam) to capture stereo images of the lunar surface at different angles. Local digital elevation models (DEMs) with a 0.02 m resolution were routinely produced at each waypoint using the Navcam and Hazcam images. These DEMs were then used to design an obstacle recognition method and establish a model for calculating the slope, aspect, roughness, and visibility. Finally, in combination with the Yutu-2 rover mobility characteristics, a comprehensive cost map for path search was generated.By the end of the first 12 lunar days, the Yutu-2 rover has been working on the lunar farside for more than 300 days, greatly exceeding the projected service life. The rover was able to overcome the complex terrain on the lunar farside, and travelled a total distance of more than 300 m, achieving the "double three hundred" breakthrough. In future manned lunar landing and exploration of Mars by China, computer vision will play an integral role to support science target selection and scientific investigations, and will become an extremely important core technology for various engineering tasks.

Operation of future lunar society in 2040

2020 ◽  
Author(s):  
Shigeru Imai
Keyword(s):  
Lunar Surface ◽  
Lunar Orbit ◽  
Circulation System ◽  
The Moon ◽  
Technology Roadmap ◽  
Use Of Resources ◽  
The World ◽  
The Individual ◽  
Operation And Management

<p><span>In 2040, a world where 1,000 people stay on the moon all the time and 10,000 people visit every year is </span><span>imagined and its feasibility and technology roadmap are discussed. </span><span>In such a world, not only the minimum</span><br /><span>infrastructure necessary for residents and travelers to survive such as habitation, transportation, power, </span><span>communication,  food  and  water, but  also  comfortable  living  and entertainment  are  required.   Also,  in </span><span>order to make a lunar society sustainable, not only the individual elements such as in-situ use of resources </span><span>(ISRU) technology and closed circulation system, which are currently being researched and developed all </span><span>over the world, but it is also important to design architecture and operate the infrastructure and facilities </span><span>on lunar surface and lunar orbit so that they work together in an organic manner to improve efficiency </span><span>and optimization as a whole.  In this session, we will present one way of thinking about the comfortable </span><span>lifestyle for residents in the 2040 lunar society, and the overall operation and management that enables a </span><span>sustainable lunar society.</span></p>

scholarly journals Research on Aluminum Honeycomb Buffer Device for Soft Landing on the Lunar Surface

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Wei Wei ◽  
Shijie Zhang ◽  
Ximing Zhao ◽  
Xinyu Quan ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Lunar Surface ◽  
Discrete Element ◽  
Honeycomb Structure ◽  
The Moon ◽  
Soft Landing ◽  
Spider Web ◽  
Buffer Material ◽  
Aluminum Honeycomb ◽  
Element Method

To obtain the resources of the moon, humans have launched a series of exploration activities on the moon, and the landing buffer device is an indispensable device on the lander required to perform lunar surface exploration missions. It can effectively protect the lander during landing scientific payloads such as instruments on the lander. Based on the mechanical properties and deformation mechanism of the aluminum honeycomb as buffer material, this paper compares and analyzes different simulation schemes and finally establishes the bonding model of the honeycomb by using the discrete element method; the parameters of the honeycomb material are matched through compression experiments to verify the discrete element honeycomb simulation and the feasibility of the scheme and its parameters. To meet the buffering requirements of large landers, a spider web honeycomb structure is proposed, its modeling method is studied by using the discrete element secondary development program, and the model is compressed as a whole to verify the energy consumption characteristics of the spider web honeycomb structure. Aiming at the honeycomb buffer device during the landing process, the cobweb honeycomb buffer structure and its corresponding landing coupling model were established using the discrete element method, the landing process was simulated and analyzed, and the landing results were predicted to verify the feasibility of the device, providing a reference for the design of the lander and its buffer device.

A Photographic Map of the Moon

1962 ◽  
Vol 14 ◽  
pp. 113-115
Author(s):  
D. W. G. Arthur ◽  
E. A. Whitaker
Keyword(s):  
Lunar Surface ◽  
The Moon ◽  
Map Projection

The cartography of the lunar surface can be split into two operations which can be carried on quite independently. The first, which is also the most laborious, is the interpretation of the lunar photographs into the symbolism of the map, with the addition of fine details from telescopic sketches. An example of this kind of work is contained in Johann Krieger'sMond Atlaswhich consists of photographic enlargements in which Krieger has sharpened up the detail to accord with his telescopic impressions. Krieger did not go on either to convert the photographic picture into the line symbolism of a map, or to place this picture on any definite map projection.

scholarly journals Development of the Statistical Model for Monitoring Salinization in the Mekong Delta of Vietnam Using Remote Sensing Data and In-Situ Measurements

Proceedings ◽  
2018 ◽  
Vol 2 (10) ◽  
pp. 565
Author(s):  
Nguyen Nguyen Vu ◽  
Le Van Trung ◽  
Tran Thi Van
Keyword(s):  
Statistical Model ◽  
Mekong Delta ◽  
Remote Sensing Data ◽  
Principal Component ◽  
Measured Data ◽  
In Situ Measurements ◽  
Landsat 8 ◽  
Spectral Bands ◽  
Component Band

This article presents the methodology for developing a statistical model for monitoring salinity intrusion in the Mekong Delta based on the integration of satellite imagery and in-situ measurements. We used Landsat-8 Operational Land Imager and Thermal Infrared Sensor (Landsat- 8 OLI and TIRS) satellite data to establish the relationship between the planetary reflectance and the ground measured data in the dry season during 2014. The three spectral bands (blue, green, red) and the principal component band were used to obtain the most suitable models. The selected model showed a good correlation with the exponential function of the principal component band and the ground measured data (R2 > 0.8). Simulation of the salinity distribution along the river shows the intrusion of a 4 g/L salt boundary from the estuary to the inner field of more than 50 km. The developed model will be an active contribution, providing managers with adaptation and response solutions suitable for intrusion in the estuary as well as the inner field of the Mekong Delta.

scholarly journals Self-Secondaries Formed by Cold Spot Craters on the Moon

2021 ◽  
Vol 13 (6) ◽  
pp. 1087
Author(s):  
Yiren Chang ◽  
Zhiyong Xiao ◽  
Yang Liu ◽  
Jun Cui
Keyword(s):  
Systematic Investigation ◽  
Impact Craters ◽  
Spatial Density ◽  
Cold Spot ◽  
The Moon ◽  
Potential Threat ◽  
Frequency Distributions ◽  
Crater Size ◽  
The Impact ◽  
Density Pattern

Self-secondaries are a population of background secondaries, and they have been observed on top of impact melt and ballistically emplaced ejecta deposits on various planetary bodies. Self-secondaries are formed by impacts of sub-vertically launched ejecta, but the launch mechanism is not confirmed. The potential threat of self-secondaries to the theoretical and applicable reliability of crater chronology has been noted, but not constrained. Hitherto discovered self-secondaries were located around complex impact craters, but their potential existence around simple craters has not been discovered. Here we report the first discovery of self-secondaries around lunar cold spot craters, which are an extremely young population of simple craters formed within the past ~1 million years on the Moon. Self-secondaries are widespread on layers of cascading flow-like ejecta deposits around cold spot craters. The spatial density of self-secondaries dwarfs that of potential primary craters. The spatial distribution of self-secondaries is highly heterogeneous across the ejecta deposits. With respect to the impactor trajectory that formed cold spot craters, self-secondaries formed at the downrange of the ejecta deposits have the largest spatial density, while those at the uprange have the smallest density. This density pattern holds for all cold spot craters that were formed by non-vertical impacts, but self-secondaries do not exhibit other systematic density variations at different radial distances or at other azimuths with respect to the impactor trajectory. Among known mechanics of ejecting materials to the exterior of impact craters, impact spallation is the most likely scenario to account for the required large ejection velocities and angles to form self-secondaries. The production population of self-secondaries is estimated based on the highly diverse crater size-frequency distributions across the ejecta deposits of cold spot craters. For a better understanding of the impact history on the Moon, a systematic investigation for the effect of self-secondaries on lunar crater chronology is required.

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