• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.284-290
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• 2014

To successfully explore the moon by lunar lander, it is essential to guarantee the safe landing of lunar lander. Therefore, efficient shock absorption system of lunar lander should be designed in order to reduce landing impact force. Also, for more practical design of lunar lander, it is important to consider the effect of lunar regolith. In the line of thought, finite element model of lunar lander considering the effect of lunar regolith is developed. To reduce landing impact force, optimization of shock absorption system for lunar lander has been carried out. In optimization, sequential approximate optimization method based on meta-model is used. Through the result of optimization, it is verified that landing impact force on lunar lander can be efficiently reduced by the present optimization procedure.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.62-76
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• 2010

In this paper, recent researches about the unmanned lunar lander development are studied. Objectives of this study are to derive research trends and to identify key design activities especially in early design phase of unmanned lunar lander. Case study covers SELENE-2 of Japan, LEDA and MoonNEXT of ESA, and small and modular spacecraft approach of NASA. Lunar lander concepts proposed for the International Lunar Network Anchor Nodes are also studied. For each lunar lander program, mission requirements are summarized and mission design results are reviewed. Approaches of safe lunar landing including design of navigation, guidance and control, combination of sensors, derived sensor and propulsion performance requirements are also analyzed.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.119-129
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• 2011

The soft landing of a lunar lander after the entrance of lunar orbit is an essential prerequisite for the accomplishment of the lander's lunar mission. During the landing process of a lunar lander, efficient shock absorption and stability maintenance are indispensible technology to protect payloads. Therefore, the landing gear is a crucial structural component of a lunar lander, it has to absorb the kinetic energy associated with touchdown and support the static load of the landing module in an upright position. In this paper, various landing gears of lunar landers which are being developed as well as which had been successfully landed on the moon surface are investigated. In the end, the Korean lunar lander, which is being designed for preliminary development model, is presented as an example of the lunar lander development.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.75-80
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• 2014

A lunar lander demonstrator developed for the purpose of demonstrating lunar landing technologies recently in Korea. The thruster control system of the lunar lander demonstrator adopted the main thrusters for altitude control and the reaction thrusters for attitude control. In this paper, we propose a path tracking controller base on Euler angles. The control signals of the controller are of continuous type. And Pulse Width Modulator(PWM) is adopted to provide On/Off signals. We perform MATLAB simulation for evaluating the path tracking performance and the final landing velocity of the lunar lander demonstrator.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.213-220
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• 2013

Korean Lunar Explorer is planned to be launched in the 2020s according to national space development strategy. The Lunar Explorer will be developed as two unmanned light weight models: a lunar orbiter and a lunar lander. The Lunar Explorer's structure should be designed to have light weight due to constraints from launcher as well as to provide structural safety against launch load, in-orbit condition and landing condition and to serve accommodation space for mission equipment. Core technology related to structural development of lunar explorer should be developed in advance. Especially, for lunar lander, technology for developing landing gear which enables lander to land safely on lunar surface is required essentially. This paper deals with structural development of lunar lander ground test model including design, manufacturing and test.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.87-93
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• 2013

The conceptual design lunar lander demonstrator has been developed to use as a test bed for advanced spacecraft technologies and to test a prototype planetary lander capable of vertical takeoff and landing. Size of the lunar lander demonstrator is the same as that of lunar lander conceptually designed, however, the weight of lunar lander demonstrator is designed in 1/6 scale in consideration of gravity difference between moon and earth. The thruster clustering and virtual flight test were performed in the demonstrator fixed on the ground. The demonstrator ground test has been conducted for two months in the test site for the solid motor combustion of the Goheung Flight Center. The purposes of ground test of demonstrator are to demonstrate and verify essential electronics, propulsion system, control algorithm, embedded software, structure and system operation technologies before developing the flight model lander. This paper is described about the virtual flight test including test configuration, test aims and test facilities

• International Journal of Aeronautical and Space Sciences
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• v.16 no.1
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• pp.102-109
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• 2015

In Korea, Lunar exploration program has been prepared with the aim of launching in the 2020's. As a part of it, a lunar lander demonstrator was developed, which was the model for verifying the system such as structure, propulsion, and control system, before launching into the deep space. This paper deals with the path tracking performance of the lunar lander demonstrator with respect to the thruster controller based on Pulse Width Pulse Frequency Modulator (PWPFM) and Pulse Width Modulator (PWM). First, we derived equations of motion, considering the allocation of the thrusters, and designed the path tracking controller based on Euler angle. The signal generated from the path tracking controller is continuous, so PWPFM and PWM modulator are adopted for generating ON/OFF signal. Finally, MATLAB simulation is performed for evaluating the path tracking ability. We compared the path tracking performances of PWPFM and PWM based thrust controller, using performance measures such as the total impulse and the position error with respect to the desired path.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.324-331
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• 2018

The thermal environment on lunar surface is more severe than that of earth's surface or low earth orbit because of the long daytime and nighttime due to 28 days of rotation cycle of moon. Thus, analyzing heat flux on lunar lander at potential landing sites is important to determine the landing site in its initial design phase. In this study, thermal model of lunar regolith that can simulate lunar surface temperature was constructed for analyzing thermal characteristics according to the potential landing sites of lunar lander. The heat flux analyses were performed various latitudes of equator, mid-latitude, polar regions, lunar mare and highland. In addition, we also investigated the heat flux of lunar lander when it is landed on adjacent area to hill.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1037-1044
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• 2014

In this study, we designed a drop test system considering lunar surface environment and tested landing gear of experimental lunar lander. The lunar lander would be landed at soil place for soft landing. When the lunar lander touches down, the acceleration of the lander is largely affected by mechanical characteristics of the lunar soil. Accordingly, a drop test using lunar soil is needed to verify the performance of the lunar landing gear. Because the lunar soil is not available generally, we developed a lunar simulant KAUMLS(Korea Aerospace University Mechanical Luna Simulant) based on mechanical properties of the lunar soil of NASA's LUNA PROJECT. In addition, drop tests on steel plate and dry sand are performed to evaluate impact characteristics by the surface environment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.27-30
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• 2011

For the successful development of korean lunar lander, the ground test is required in order to verify performance of propulsion system, attitude control system, performance of landing device and etc. In order to develop the lunar lander ground test model, development of large size thruster and pressure regulated propulsion system is now in progress. In this paper, the results of 200N class monopropellant thruster development and propulsion system design will be presented.