• Title/Summary/Keyword: Korea Pathfinder Lunar Orbiter (KPLO)

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Burn Delay Analysis of the Lunar Orbit Insertion for Korea Pathfinder Lunar Orbiter

  • Bae, Jonghee;Song, Young-Joo;Kim, Young-Rok;Kim, Bangyeop
    • Journal of Astronomy and Space Sciences
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    • v.34 no.4
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    • pp.281-288
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    • 2017
  • The first Korea lunar orbiter, Korea Pathfinder Lunar Orbiter (KPLO), has been in development since 2016. After launch, the KPLO will execute several maneuvers to enter into the lunar mission orbit, and will then perform lunar science missions for one year. Among these maneuvers, the lunar orbit insertion (LOI) is the most critical maneuver because the KPLO will experience an extreme velocity change in the presence of the Moon's gravitational pull. However, the lunar orbiter may have a delayed LOI burn during operation due to hardware limitations and telemetry delays. This delayed burn could occur in different captured lunar orbits; in the worst case, the KPLO could fly away from the Moon. Therefore, in this study, the burn delay for the first LOI maneuver is analyzed to successfully enter the desired lunar orbit. Numerical simulations are performed to evaluate the difference between the desired and delayed lunar orbits due to a burn delay in the LOI maneuver. Based on this analysis, critical factors in the LOI maneuver, the periselene altitude and orbit period, are significantly changed and an additional delta-V in the second LOI maneuver is required as the delay burn interval increases to 10 min from the planned maneuver epoch.

Korea Pathfinder Lunar Orbiter Flight Dynamics Simulation and Rehearsal Results for Its Operational Readiness Checkout

  • Song, Young-Joo;Bae, Jonghee;Hong, SeungBum;Bang, Jun
    • Journal of Astronomy and Space Sciences
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    • v.39 no.4
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    • pp.181-194
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    • 2022
  • Korea Pathfinder Lunar Orbiter (KPLO), also known as Danuri, was successfully launched on 4 Aug. from Cape Canaveral Space Force Station using a Space-X Falcon-9 rocket. Flight dynamics (FD) operational readiness was one of the critical parts to be checked before the flight. To demonstrate FD software's readiness and enhance the operator's contingency response capabilities, KPLO FD specialists planned, organized, and conducted four simulations and two rehearsals before the KPLO launch. For the efficiency and integrity of FD simulation and rehearsal, different sets of blind test data were prepared, including the simulated tracking measurements that incorporated dynamical model errors, maneuver execution errors, and other errors associated with a tracking system. This paper presents the simulation and rehearsal results with lessons learned for the KPLO FD operational readiness checkout. As a result, every functionality of FD operation systems is firmly secured based on the operation procedure with an enhancement of contingency operational response capability. After conducting several simulations and rehearsals, KPLO FD specialists were much more confident in the flight teams' ability to overcome the challenges in a realistic flight and FD software's reliability in flying the KPLO. Moreover, the results of this work will provide numerous insights to the FD experts willing to prepare deep space flight operations.

Practical Algorithms on Lunar Reference Frame Transformations for Korea Pathfinder Lunar Orbiter Flight Operation

  • Song, Young-Joo;Lee, Donghun;Kim, Young-Rok;Bae, Jonghee;Park, Jae-ik;Hong, SeungBum;Kim, Dae-Kwan;Lee, Sang-Ryool
    • Journal of Astronomy and Space Sciences
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    • v.38 no.3
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    • pp.185-192
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    • 2021
  • This technical paper deals the practical transformation algorithms between several lunar reference frames which will be used for Korea pathfinder lunar orbiter (KPLO) flight operation. Despite of various lunar reference frame definitions already exist, use of a common transformation algorithm while establishing lunar reference frame is very important for all members related to KPLO mission. This is because use of slight different parameters during frame transformation may result significant misleading while reprocessing data based on KPLO flight dynamics. Therefore, details of practical transformation algorithms for the KPLO mission specific lunar reference frames is presented with step by step implementation procedures. Examples of transformation results are also presented to support KPLO flight dynamics data user community which is expected to give practical guidelines while post processing the data as their needs. With this technical paper, common understandings of reference frames that will be used throughout not only the KPLO flight operation but also science data reprocessing can be established. It is expected to eliminate, or at least minimize, unnecessary confusion among all of the KPLO mission members including: Korea Aerospace Research Institute (KARI), National Aeronautics and Space Administration (NASA) as well as other organizations participating in KPLO payload development and operation, or further lunar science community world-wide who are interested in KPLO science data post processing.

Preparation of Contingency Trajectory Operation for the Korea Pathfinder Lunar Orbiter

  • Jun Bang;SeungBum Hong;Jonghee Bae;Young-Joo Song;Donghun Lee
    • Journal of Astronomy and Space Sciences
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    • v.40 no.4
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    • pp.217-224
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    • 2023
  • The Korea Pathfinder Lunar Orbiter (KPLO), also known as Danuri, successfully entered its mission orbit on December 27, 2022 (UTC), and is currently performing its mission smoothly. To mitigate potential contingencies during the flight and to navigate the spacecraft into the desired lunar orbit, the KPLO flight dynamics (FD) team analyzed major trajectory-related contingencies that could lead to the violation of mission requirements and prepared operational procedures from the perspective of trajectory and FD. This paper presents the process of preparing contingency trajectory operations for the KPLO, including the identification of trajectory contingencies, prioritization results, and the development of recovery plans and operational procedures. The prepared plans were successfully applied to address minor contingencies encountered during actual operations. The results of this study will provide valuable insights to FD engineers preparing for space exploration mission operations.

Post Trajectory Insertion Performance Analysis of Korea Pathfinder Lunar Orbiter Using SpaceX Falcon 9

  • Young-Joo Song;Jonghee Bae;SeungBum Hong;Jun Bang;Donghun Lee
    • Journal of Astronomy and Space Sciences
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    • v.40 no.3
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    • pp.123-129
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    • 2023
  • This paper presents an analysis of the trans-lunar trajectory insertion performance of the Korea Pathfinder Lunar Orbiter (KPLO), the first lunar exploration spacecraft of the Republic of Korea. The successful launch conducted on August 4, 2022 (UTC), utilized the SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station. The trans-lunar trajectory insertion performance plays a crucial role in ensuring the overall mission success by directly influencing the spacecraft's onboard fuel consumption. Following separation from the launch vehicle (LV), a comprehensive analysis of the trajectory insertion performance was performed by the KPLO flight dynamics (FD) team. Both orbit parameter message (OPM) and orbit determination (OD) solutions were employed using deep space network (DSN) tracking measurements. As a result, the KPLO was accurately inserted into the ballistic lunar transfer (BLT) trajectory, satisfying all separation requirements at the target interface point (TIP), including launch injection energy per unit mass (C3), right ascension of the injection orbit apoapsis vector (RAV), and declination of the injection orbit apoapsis vector (DAV). The precise BLT trajectory insertion facilitated the smoother operation of the KPLO's remainder mission phase and enabled the utilization of reserved fuel, consequently significantly enhancing the possibilities of an extended mission.

Development of Kinematic Ephemeris Generator for Korea Pathfinder Lunar Orbiter (KPLO)

  • Song, Min-Sup;Park, Sang-Young;Kim, Youngkwang;Yim, Jo Ryeong
    • Journal of Astronomy and Space Sciences
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    • v.37 no.3
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    • pp.199-208
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    • 2020
  • This paper presents a kinematic ephemeris generator for Korea Pathfinder Lunar Orbiter (KPLO) and its performance test results. The kinematic ephemeris generator consists of a ground ephemeris compressor and an onboard ephemeris calculator. The ground ephemeris compressor has to compress desired orbit propagation data by using an interpolation method in a ground system. The onboard ephemeris calculator can generate spacecraft ephemeris and the Sun/Moon ephemeris in onboard computer of the KPLO. Among many interpolation methods, polynomial interpolation with uniform node, Chebyshev interpolation, Hermite interpolation are tested for their performances. As a result of the test, it is shown that all the methods have some cases that meet requirements but there are some performance differences. It is also confirmed that, the Chebyshev interpolation shows better performance than other methods for spacecraft ephemeris generation, and the polynomial interpolation with uniform nodes yields good performance for the Sun/Moon ephemeris generation. Based on these results, a Kinematic ephemeris generator is developed for the KPLO mission. Then, the developed ephemeris generator can find an approximating function using interpolation method considering the size and accuracy of the data to be transmitted.

Observational Arc-Length Effect on Orbit Determination for Korea Pathfinder Lunar Orbiter in the Earth-Moon Transfer Phase Using a Sequential Estimation

  • Kim, Young-Rok;Song, Young-Joo
    • Journal of Astronomy and Space Sciences
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    • v.36 no.4
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    • pp.293-306
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    • 2019
  • In this study, the observational arc-length effect on orbit determination (OD) for the Korea Pathfinder Lunar Orbiter (KPLO) in the Earth-Moon Transfer phase was investigated. For the OD, we employed a sequential estimation using the extended Kalman filter and a fixed-point smoother. The mission periods, comprised between the perigee maneuvers (PM) and the lunar orbit insertion (LOI) maneuver in a 3.5 phasing loop of the KPLO, was the primary target. The total period was divided into three phases: launch-PM1, PM1-PM3, and PM3-LOI. The Doppler and range data obtained from three tracking stations [included in the deep space network (DSN) and Korea Deep Space Antenna (KDSA)] were utilized for the OD. Six arc-length cases (24 hrs, 48 hrs, 60 hrs, 3 days, 4 days, and 5 days) were considered for the arc-length effect investigation. In order to evaluate the OD accuracy, we analyzed the position uncertainties, the precision of orbit overlaps, and the position differences between true and estimated trajectories. The maximum performance of 3-day OD approach was observed in the case of stable flight dynamics operations and robust navigation capability. This study provides a guideline for the flight dynamics operations of the KPLO in the trans-lunar phase.

Lessons Learned from Korea Pathfinder Lunar Orbiter Flight Dynamics Operations: NASA Deep Space Network Interfaces and Support Levels

  • Young-Joo Song;SeungBum Hong;Dong-Gyu Kim;Jun Bang;Jonghee Bae
    • Journal of Astronomy and Space Sciences
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    • v.40 no.2
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    • pp.79-88
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    • 2023
  • On Aug. 4, 2022, at 23:08:48 (UTC), the Korea Pathfinder Lunar Orbiter (KPLO), also known as Danuri, was launched using a SpaceX Falcon 9 launch vehicle. Currently, KPLO is successfully conducting its science mission around the Moon. The National Aeronautics and Space Administration (NASA)'s Deep Space Network (DSN) was utilized for the successful flight operation of KPLO. A great deal of joint effort was made between the Korea Aerospace Research Institute (KARI) and NASA DSN team since the beginning of KPLO ground system design for the success of the mission. The efficient utilization and management of NASA DSN in deep space exploration are critical not only for the spacecraft's telemetry and command but also for tracking the flight dynamics (FD) operation. In this work, the top-level DSN interface architecture, detailed workflows, DSN support levels, and practical lessons learned from the joint team's efforts are presented for KPLO's successful FD operation. Due to the significant joint team's efforts, KPLO is currently performing its mission smoothly in the lunar mission orbit. Through KPLO cooperative operation experience with DSN, a more reliable and efficient partnership is expected not only for Korea's own deep space exploration mission but also for the KARI-NASA DSN joint support on other deep space missions in the future.

Korea Pathfinder Lunar Orbiter Magnetometer Instrument and Initial Data Processing

  • Wooin Jo;Ho Jin;Hyeonhu Park;Yunho Jang;Seongwhan Lee;Khan-Hyuk Kim;Ian Garrick-Bethell;Jehyuck Shin;Seul-Min Baek;Junhyun Lee;Derac Son;Eunhyeuk Kim
    • Journal of Astronomy and Space Sciences
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    • v.40 no.4
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    • pp.199-215
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    • 2023
  • The Korea Pathfinder Lunar Orbiter (KPLO), the first South Korea lunar exploration probe, successfully arrived at the Moon on December, 2022 (UTC), following a 4.5-month ballistic lunar transfer (BLT) trajectory. Since the launch (4 August, 2022), the KPLO magnetometer (KMAG) has carried out various observations during the trans-lunar cruise phase and a 100 km altitude lunar polar orbit. KMAG consists of three fluxgate magnetometers capable of measuring magnetic fields within a ± 1,000 nT range with a resolution of 0.2 nT. The sampling rate is 10 Hz. During the originally planned lifetime of one year, KMAG has been operating successfully while performing observations of lunar crustal magnetic fields, magnetic fields induced in the lunar interior, and various solar wind events. The calibration and offset processes were performed during the TLC phase. In addition, reliabilities of the KMAG lunar magnetic field observations have been verified by comparing them with the surface vector mapping (SVM) data. If the KPLO's mission orbit during the extended mission phase is close enough to the lunar surface, KMAG will contribute to updating the lunar surface magnetic field map and will provide insights into the lunar interior structure and lunar space environment.

KARI Planetary Data System for Science Research Support in Korea Pathfinder Lunar Orbiter Program

  • Kim, Joo Hyeon
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.55.3-55.3
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    • 2019
  • 우리나라 최초의 우주탐사 프로그램인 Korea Pathfinder Lunar Orbiter (KPLO)는 1년의 임무기간동안 달과 달 주변의 우주환경에 대한 과학탐사 임무를 수행할 예정이다. 이를 위해서 1개에 기술 검증장비와 고해상도 카메라를 포함한 5개의 과학장비를 탑재할 예정이다. 이 중 고해상도 카메라인 LUTI(LUnar Terrain Imager)와 국내에서 개발한 3개의 과학탑재체(KGRS;감마선분광기, KMAG;자기장측정기, PolCam;광시야 편광카메라)가 획득한 과학자료는 일정기간(통상 1년)동안 비공개로 검보정이 이루어진 후 일반에게 공개(Public release)할 예정이다. 이러한 과학자료의 공개와 관리를 위해서 한국항공우주연구원은 KPLO 심우주 지상시스템 내에 과학자료의 공개 및 관리를 위한 KARI Planetary Data System(KPDS)을 개발하고 있다. KPDS는 미국 NASA의 PDS에서 개발하여 유럽, 일본 등에서 이미 행성탐사 과학자료의 표준으로 활용하고 있는 PDS4 표준을 준수하는 과학자료를 제공할 것이다. 본 발표를 통해서 KPDS의 운영개념과 과학자료 관리계획, 그리고 KPDS의 개발현황을 천문학계와 공유하여 KPLO에 의해서 획득된 과학자료가 많은 과학자들이 활용하여 높은 과학적 성과를 낼 수 있기를 기대한다.

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