• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.311-314
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• 2005

We report the current status of Japanese lunar exploration SELENE (SELenological and ENgineering Explorer). As of the end of 2004, scientific instruments onboard the Main Orbiter are under final checkout before they are provided to the proto-flight-model (PFM) integration test. Also, we present the future perspectives of the lunar based instruments and facilities. 'In-situ Lunar Orientation Mea-surement (ILOM)' experiment measures the lunar rotation with high accuracy by tracking stars on the Moon with a small photo-zenith-tube type optical telescope. A basic idea of a radio telescope array of very low frequency range on the lunar far-side is also mentioned.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.1-25
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• 2023

In this paper, I briefly introduce recently terminated, current, and future scientific spacecraft missions for in situ and remote-sensing observations of Earth's and other planetary magnetospheres as of February 2023. The spacecraft introduced here are Geotail, Cluster, Time History of Events and Macroscale Interactions during Substorms / Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (THEMIS / ARTEMIS), Magnetospheric Multiscale (MMS), Exploration of energization and Radiation in Geospace (ERG), Cusp Plasma Imaging Detector (CuPID), and EQUilibriUm Lunar-Earth point 6U Spacecraft (EQUULEUS) for recently terminated or currently operated missions for Earth's magnetosphere; Lunar Environment Heliospheric X-ray Imager (LEXI), Gateway, Solar wind Magneto-sphere Ionosphere Link Explorer (SMILE), HelioSwarm, Solar-Terrestrial Observer for the Response of the Magnetosphere (STORM), Geostationary Transfer Orbit Satellite (GTOSat), GEOspace X-ray imager (GEO-X), Plasma Observatory, Magnetospheric Constellation (MagCon), self-Adaptive Magnetic reconnection Explorer (AME), and COnstellation of Radiation BElt Survey (CORBES) approved for launch or proposed for future missions for Earth's magnetosphere; BepiColombo for Mercury and Juno for Jupiter for current missions for planetary magnetospheres; Jupiter Icy Moons Explorer (JUICE) and Europa Clipper for Jupiter, Uranus Orbiter and Probe (UOP) for Uranus, and Neptune Odyssey for Neptune approved for launch or proposed for future missions for planetary magnetospheres. I discuss the recent trend and future direction of spacecraft missions as well as remaining challenges in magnetospheric research. I hope this paper will be a handy guide to the current status and trend of magnetospheric missions.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.161-166
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• 2015

Analysis of lunar samples returned by the US Apollo missions revealed that the lunar highlands consist of anorthosite, plagioclase, pyroxene, and olivine; also, the lunar maria are composed of materials such as basalt and ilmenite. More recently, the remote sensing approach has enabled reduction of the time required to investigate the entire lunar surface, compared to the approach of returning samples. Moreover, remote sensing has also made it possible to determine the existence of specific minerals and to examine wide areas. In this paper, an investigation was performed on the reflectance distribution and its trend. The results were applied to the example of the double ray stretched in parallel lines from the Tycho crater to the third-quadrant of Mare Nubium. Basic research and background information for the investigation of lunar surface characteristics is also presented. For this research, resources aboard the SELenological and ENgineering Explorer (SELENE), a Japanese lunar probe, were used. These included the Multiband Imager (MI) in the Lunar Imager/Spectrometer (LISM). The data of these instruments were edited through the toolkit, an image editing and analysis tool, Exelis Visual Information Solution (ENVI).

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.65.1-65.1
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• 2014

달에 떨어지는 유성체(lunar meteoroid)는 그대로 표면에 충돌하여 섬광(flash)을 일으킨다. 이 현상은 매우 희미하고 순간적이지만 고감도 비디오카메라를 이용하면 지상 관측이 가능하다고 알려져 있다. 2013년 10월에 발사된 NASA의 Lunar Atmosphere and Dust Environment Explorer(LADEE)가 달 주위의 대기 및 먼지 환경을 측정하고 있는 동안 전 세계 지상관측 네트워크도 달 표면 충돌 감시 관측을 수행 중에 있다. 충남대학교에서도 LADEE 미션 시작인 10월부터 16인치 망원경에 고감도 비디오카메라를 장착한 시스템을 구성하여 매달 초승부터 상현까지 관측을 진행해왔다. 관측은 달 표면의 어두운 영역을 초당 30프레임으로 녹화하였으며, NASA에서 제공한 LunarScan 소프트웨어를 사용하여 섬광을 찾는 분석 작업을 수행하였다. 현재까지 약 70시간 동안 관측하고 분석하여 충돌 섬광 후보를 발견하였다. 본 발표에서 달 충돌 섬광 관측시스템에 대해 소개하고, 관측된 충돌 섬광 후보의 분석 결과를 제시할 것이다.

• Journal of Astronomy and Space Sciences
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• v.28 no.3
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• pp.203-216
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• 2011

To prepare for a future Korean lunar orbiter mission, semi-optimal lunar capture orbits using finite thrust are designed and analyzed. Finite burn delta-V losses during lunar capture sequence are also analyzed by comparing those with values derived with impulsive thrusts in previous research. To design a hypothetical lunar capture sequence, two different intermediate capture orbits having orbital periods of about 12 hours and 3.5 hours are assumed, and final mission operation orbit around the Moon is assumed to be 100 km altitude with 90 degree of inclination. For the performance of the on-board thruster, three different performances (150 N with $I_{sp}$ of 200 seconds, 300 N with $I_{sp}$ of 250 seconds, 450 N with $I_{sp}$ of 300 seconds) are assumed, to provide a broad range of estimates of delta-V losses. As expected, it is found that the finite burn-arc sweeps almost symmetric orbital portions with respect to the perilune vector to minimize the delta-Vs required to achieve the final orbit. In addition, a difference of up to about 2% delta-V can occur during the lunar capture sequences with the use of assumed engine configurations, compared to scenarios with impulsive thrust. However, these delta-V losses will differ for every assumed lunar explorer's on-board thrust capability. Therefore, at the early stage of mission planning, careful consideration must be made while estimating mission budgets, particularly if the preliminary mission studies were assumed using impulsive thrust. The results provided in this paper are expected to lead to further progress in the design field of Korea's lunar orbiter mission, particularly the lunar capture sequences using finite thrust.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.121-125
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• 2015

At the suggestion of the NASA Meteoroid Environment Office (NASA/MEO), which promotes lunar impact monitoring worldwide during NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) mission period (launched Sept. 2013), we set up a video observation system for lunar impact flashes using a 16-inch educational telescope at Chungnam National University. From Oct. 2013 through Apr. 2014, we recorded 80 hours of video observation of the unilluminated part of the crescent moon in the evening hours. We found a plausible candidate impact flash on Feb. 3, 2014 at selenographic longitude $2.1^{\circ}$ and latitude $25.4^{\circ}$. The flash lasted for 0.2 s and the light curve was asymmetric with a slow decrease after a peak brightness of $8.7{\pm}0.3mag$. Based on a star-like distribution of pixel brightness and asymmetric light curve, we conclude that the observed flash was due to a meteoroid impact on the lunar surface. Since unequivocal detection of an impact flash requires simultaneous observation from at least two sites, we strongly recommend that other institutes and universities in Korea set up similar inexpensive monitoring systems involving educational or amateur telescopes, and that they collaborate in the near future.

• Journal of Astronomy and Space Sciences
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• v.26 no.2
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• pp.171-186
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• 2009

Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI(Trans Lunar Injection) maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.741-757
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• 2016

Over 60 years has passed since mankinds started space exploration beyond the Earth with lunar explorer Luna 1 launched by Soviet Union. Unprecedently remarkable outcomes have been obtained by sending unmanned spacecrafts to most planets in the solar system and having the lander landed on the approaching comet toward the Earth even though any evidence of life presence has not been discovered yet. Only moon is an natural object beyond the earth on which human beings landed. Many countries are planning to send humans to the moon or mars to build colonies and to survive with substantiality. Korean lunar exploration program has officially started as of 2016 after its plan including lunar exploration has been specified in the series of National Space Promotion Plan since Korea initiated space development in early 1990s. In this paper, the plan for Korean space exploration is summarized with reviewing overseas space exploration program status and trends.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.169.1-169.1
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• 2012

한국항공우주연구원에서는 2010년부터 달착륙선 지상 시험모델 개발을 진행하고 있으며 2012년 하반기에 추력 시험을 비롯한 전반적인 전장계 및 소프트웨어계 통합 시험을 계획하고 있다. 본 통합 시험은 탑재 컴퓨터와 VDE를 비롯한 전자 장비가 올바르게 동작하고 있는지 확인하고 소프트웨어가 이들을 잘 제어하고 있는지에 대한 시험 및 하이드라진 추력 시스템에서 본체로부터 명령을 잘 전송받아 적절한 추력을 발생시키고 있는지에 대한 시험 2가지로 크게 구분된다. 통합시험을 통해서 통신 시험용 도구(LECT, Lunar Explorer Communication Tool)에 대한 성능 검증도 같이 수행될 예정이다. 소프트웨어계에 대해서는 각 소프트웨어 모듈에 대한 단위 시험 및 통신 시험용 도구와 연결될 상태에서 통합 성능 시험이 수행될 예정이다. 통합 시험을 앞두고 전장계 및 소프트웨어계의 최종 성능 점검을 위해서 데이터 획득 시스템을 구성하여 입력 및 출력을 모든 채널에 대해서 관찰함으로 다양한 운용 시나리오 하에서 예측된 결과를 보이는지 확인할 예정이며 본 논문에서는 상기 최종 점검 환경에 대한 개념 및 규격, 그리고 제작, 운용 및 시험에 대한 내용을 기술한다.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.127-133
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• 2014

In this paper, we present the design, functions and performance analysis of the virtual machine (VM) based on the Lua interpreter for On-Board Control Procedure Execution Environment (OEE). The development of the OEE has been required in order to operate the lunar explorer mission autonomously which is planned by Korea Aerospace Research Institute (KARI) autonomously. The concept of On-Board Control Procedure (OBCP) is already being applied to the deep space missions with a long propagation delay and a limited data transmission capacity since it ensure he autonomy of the mission without the ground intervention. The interpreter is the execution engine in the VM and it interpreters high-level programming codes line by line and executes the VM instructions. So the execution speed is very more slower than that of natively compiled codes. In order to overcome it, we design and implement OEE using register-based Lua interpreter for execution engine in OEE. We present experimental results on a range of additional hardware configurations such as usages of cache and floating point unit. We expect those to utilized to the OBCP scheduling policy and the system with Lua interpreter.