• International Journal of Aeronautical and Space Sciences
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• v.14 no.4
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• pp.356-368
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• 2013

The Korea Aerospace Research Institute plans to launch a lunar module by 2025, and so is carrying out a preliminary study. Landing stability on the lunar surface is a key design factor of a lunar module. In this paper, a 1/6 scale model of a lunar module is investigated, for its landing stability on non-level surfaces. The lunar module has four tripod legs, with aluminum honeycomb shock absorbers in each leg strut. ADAMS$^{TM}$, the most widely used multi-body dynamics and motion analysis software, is used to simulate the module's lunar landing. Three types of dampers in the struts (rigid, viscous, and aluminum honeycomb dampers), and two types of lunar surfaces (rigid and elastic) are considered. The Sforce function is adopted, to model the aluminum honeycomb dampers. Details on the modeling and analysis of the landing stability of the 1/6 scale lunar module and the simulation results are provided in this paper.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.125-134
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• 2022

The Global Expansion Roadmap published by the International Space Exploration Coordination Group, which is organized by space agencies around the world, presents future lunar exploration guidance and stresses a lunar habitat program to utilize lunar resources. The Moon attracts attention as an outpost for deep space exploration. Simulating lunar surface environments is required to evaluate the performances of various equipment for future lunar surface missions. In this paper, an experimental study was conducted to simulate high vacuum pressure and cryogenic temperature of the permanent shadow regions in the lunar south pole, which is a promising candidate for landing and outpost construction. The establishment of an efficient dirty thermal vacuum chamber (DTVC) operation process has never been presented. One-dimensional ground cooling tests were conducted with various vacuum pressures with the Korean Lunar Simulant type-1 (KLS-1) in DTVC. The most advantageous vacuum pressure was found to be 30-80 mbar, considering the cooling efficiency and equipment stability. However, peripheral cooling is also required to simulate a cryogenic for not sublimating ice in a high vacuum pressure. In this study, an efficient peripheral cooling operation process was proposed by applying the frost ratio concept.

• Tunnel and Underground Space
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• v.32 no.2
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• pp.131-143
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• 2022

The lunar exploration autonomous vehicle operates based on the lunar topography information obtained from real-time image characterization. For highly accurate topography characterization, a large number of training images with various background conditions are required. Since the real lunar topography images are difficult to obtain, it should be helpful to be able to generate mimic lunar image data artificially on the basis of the planetary analogs site images and real lunar images available. In this study, we aim to artificially create lunar topography images by using the location information-based style transfer algorithm known as Wavelet Correct Transform (WCT2). We conducted comparative experiments using lunar analog site images and real lunar topography images taken during China's and America's lunar-exploring projects (i.e., Chang'e and Apollo) to assess the efficacy of our suggested approach. The results show that the proposed techniques can create realistic images, which preserve the topography information of the analog site image while still showing the same condition as an image taken on lunar surface. The proposed algorithm also outperforms a conventional algorithm, Deep Photo Style Transfer (DPST) in terms of temporal and visual aspects. For future work, we intend to use the generated styled image data in combination with real image data for training lunar topography objects to be applied for topographic detection and segmentation. It is expected that this approach can significantly improve the performance of detection and segmentation models on real lunar topography images.

• Journal of Astronomy and Space Sciences
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• v.41 no.2
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• pp.79-85
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• 2024

Nowadays, the trend in lunar exploration missions is shifting from prospecting lunar surface to utilizing in-situ resources and establishing sustainable bridgehead. In the past, experiments were mainly focused on rover maneuvers and equipment operations. But the current shift in trend requires more complex experiments that includes preparations for resource extraction, space construction and even space agriculture. To achieve that, the experiment requires a sophisticated simulation of the lunar environment, but we are not yet prepared for this. Particularly, in the case of lunar regolith simulants, precise physical and chemical composition with a rapid development speed rate that allows different terrains to be simulated is required. However, existing lunar regolith simulants, designed for 20th-century exploration paradigms, are not sufficient to meet the requirements of modern space exploration. In order to prepare for the latest trends in space exploration, it is necessary to innovate the methodology for producing simulants. In this study, the basic framework for lunar regolith simulant development was established to realize this goal. The framework not only has a sample database and a database of potential simulation target compositions, but also has a built-in function to automatically calculate the optimal material mixing ratio through the particle swarm optimization algorithm to reproduce the target simulation, enabling fast and accurate simulant development. Using this framework, we anticipate a more agile response to the evolving needs toward simulants for space exploration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.144-152
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• 2018

Lunar exploration, which was led by the United States and the former Soviet Union, ceased in the 1970s. On the other hand, since massive lunar ice deposits and rare resources were found in 1990s, European Union, China, Japan, and India began to participate in lunar exploration to secure future lunar resource as well as to construct a lunar base. In the near future, it is expected that national space agencies and private industries will participate in the lunar exploration together. Their missions will include the exploration and sample return of lunar resources. Lunar resources have a close relationship with the lunar in-situ resource utilization (ISRU). To construct a lunar base, it is inevitable to bring huge amounts of resources from Earth. Water and oxygen, however, will need to be produced from local lunar resources and lunar terrain feature will need to be used to construct the lunar base. Therefore, in this paper, the global trends on lunar exploration and lunar construction technology are investigated and compared along with the ISRU technology to support human exploration and construct a lunar base on the Moon's surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.669-676
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• 2018

As the Moon's scientific, technological, and economic value has increased, major space agencies around the world are leading lunar exploration projects by establishing a road map to develop lunar resources and to construct a lunar base. In addition, as the lunar base construction requires huge amounts of resources from the Earth, lunar in-situ construction technology is being developed to produce construction materials from local lunar resources. On the other hand, the characteristics of lunar topography and resources vary spatially due to the crustal and volcanic activities inside the Moon as well as the solar wind and meteorites from outside the Moon. Therefore, in this paper, the geospatial analysis of lunar resource distribution was conducted to suggest regional consideration factors to apply the lunar in situ construction technologies. In addition, the lunar topographic condition to select construction sites was suggested to ensure the safe landing of a lunar lander and the easy maneuvering of a rover. The lunar topographic and resource information mainly from lunar orbiters were limited to the lunar surface with a low spatial resolution. Rover-based lunar exploration in the near future is expected to provide valuable information to develop lunar in situ construction technology and select candidate sites for lunar base construction.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.531-536
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• 2003

In this paper, a redesigned guidance and control system for a lunar lander is presented. In past studies, the authors developed a trajectory and attitude control system which achieves the vertical soft landing on the lunar surface. It is confirmed that the system has a good tracking ability to a predefined profile and good robustness against a thruster failure mode where a partial failure of clustered engines was assumed. However, under the previous control laws, the landing point tends to be shifted, in response to the system parameter values, from a target point. Also, an unbalanced moment due to a thruster failure mode was not considered in the simulation. Therefore, in this study, the downrange control is added to the system to enable the vehicle to land at a pre-assigned target point accurately. Furthermore, inhibiting the effect of the unbalanced moment is attempted thorough redesigning the attitude control system. A numerical simulation was performed to confirm the ability of the proposed system with regard to the above problems. Moreover, in the past simulations, a low initial altitude was assumed as an initial condition: in this study, however, the performance of the proposed system is examined over the whole trajectory from an initial altitude of 10 [km] to the lunar surface.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.50-54
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• 2014

Evaluation of the possible or probable effects of environmental conditions which are temperature, radiation, dust as well as other possibilities in terms of meteoroids, seismicity, and no global magnetic field has been carried out for wireless communications on the lunar surface in this paper. The results considered in this paper can be utilized as a basic information on making efficient use of the design for wireless communications system in Korean lunar exploration project.

• Journal of The Korean Astronomical Society
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• v.55 no.3
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• pp.75-86
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• 2022

The lunar surface progressively darkens and reddens as a result of sputtering from solar wind particles and bombardment of micrometeoroids. The extent of exposure to these space weathering agents is frequently calculated as the location in a diagram of reflectance at 750 nm vs. 950 nm/750 nm color (R-C). Sim & Kim (2018) examined the R-C trends of pixels within ~3,500 craters, and revealed that the length (L) and skewness (s) of R-C trends can be employed as a secondary age or maturity indicator. We broaden this research to general lunar surface areas (3,400 tiles of 0.25° × 0.25° size) in 218 mare basalt units, whose ages have been derived from the size-frequency distribution analysis by Hiesinger et al. (2011). We discover that L and s rise with age until ~3.2 Gyr and reduce rather rapidly afterward, while the optical maturity, OMAT, reduces monotonically with time. We show that in some situations, when not only OMAT but also L and s are incorporated in the estimation utilizing 750 & 950 nm photometry, the age estimation becomes considerably more reliable. We also observed that OMAT and the lunar cratering chronology function (cumulative number of craters larger than a certain diameter as a function of time) have a relatively linear relationship.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.48.2-48.2
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• 2021

The lunar surface progressively darkens and reddens as a result of sputtering from solar wind particles and bombardment of micrometeoroids. The extent of exposure to these space weathering agents is frequently calculated as the location in a diagram of reflectance at 750 nm vs. 950 nm/750 nm color (R-C). Sim & Kim (2018) examined the R-C trends of pixels within ~3,500 craters, and revealed that the length (L) and skewness (s) of R-C trends can be employed as a secondary age or maturity indicator. We broaden this research to general lunar surface areas (3,400 tiles of 0.25° × 0.25° size) in 218 mare basalt units, whose ages have been derived from the size-frequency distribution analysis by Hiesinger et al. (2011). We discover that L and s rise with age until ~3.2 Gyr and reduce rather rapidly afterward, while the optical maturity, OMAT, reduces monotonically with time. We show that in some situations, when not only OMAT but also L and s are incorporated in the estimation utilizing 750 & 950 nm photometry, the age estimation becomes considerably more reliable. We also observed that OMAT and the lunar cratering chronology function (cumulative number of craters larger than a certain diameter as a function of time) have a relatively linear relationship.