• Title/Summary/Keyword: Satellite Laser Ranging (SLR)

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Effective Strategy for Precise Orbital and Geodetic Parameter Estimation Using SLR Observations for ILRS AAC

  • Kim, Young-Rok;Oh, Jay;Park, Sang-Young;Park, Chandeok;Park, Eun-Seo;Lim, Hyung-Chul
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.159.2-159.2
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    • 2012
  • In this study, we propose an effective strategy for precise orbital and geodetic parameter estimation using SLR (Satellite Laser Ranging) observations for ILRS AAC (Associate Analysis Center). The NASA/GSFC GEODYN II software and SLR normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 are utilized for precise orbital and geodetic parameter estimation. Weekly-based precise orbit determination strategy is applied to process SLR observations, and Precise Orbit Ephemeris (POE), TRF (Terrestrial Reference Frame), and EOPs (Earth Orientation Parameters) are obtained as products of ILRS AAC. For improved estimation results, selection strategies of dynamic and measurement models are experimently figured out and configurations of various estimation parameters are also carefully chosen. The results of orbit accuracy assessment of POE and precision analysis of TRF/EOPs for each case are compared with those of existing results. Finally, we find an appropriate strategy for precise orbital and geodetic parameter estimation using SLR observations for ILRS AAC.

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Preliminary Design of Korea's First mobile SLR system

  • Jo, Jung-Hyun;Seo, Yoon-Kyung;Lee, Jin-Young;Yim, Hong-Seo;Lim, Hyung-Chul;Park, Eun-Seo;Park, Jang-Hyun;Park, Jong-Uk
    • Bulletin of the Korean Space Science Society
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    • 2010.04a
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    • pp.36.2-36.2
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    • 2010
  • Followed the System Design Review (PDR) of a mobile SLR (Satellite Laser Ranging) system, a successful preliminary design review was finished in 2009. With the completion of this mobile SLR system, KASI (Korea Astronomy and Space Science Institute) can perform a series of test observation and calibration/validation procedures. After the operation performance of the whole system reaches the nominal design, a regular scheduled observation will be executed. However, the project has been disturbed by the frequent change of working staff, budget profile, and plan as well as the inexperienced man power. In this study, the contents and the issues of PDR are briefly reviewed and several items of SLR system are suggested. This mobile SLR system will push Korea's Space Geodetic study further and will make us jump to another step to the Space Science in Korea.

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PRECISE RANGE DETERMINATION USING LASER RANGING DATA OF LAGEOSE II (LAGEOS II 위성의 LASER 관측자료를 이용한 정밀거리 결정)

  • 김광열;김형규;장홍술;손건호;최규홍
    • Journal of Astronomy and Space Sciences
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    • v.10 no.2
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    • pp.189-196
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    • 1993
  • Satellite laser ranging observation of LAGEOS II has been performed using the SLR System at Sheshan Laser Ranging Station, Shanghai Observatory. And we obtained 1,838 observational points. The observed range data is corrected by means of system delay correction using ground target observation, atmospheric refraction delay correction, offset correction, general relativistic correction and tide correction including solid tide, polar tide and ocean tide. As a result, the determined range delay mean value is 19.12m and the mean internal accuracy by means of polynomial fitting and least square method is $\pm$7cm. Corrected observational points are 1,340 and noise ratio to total observational points is 27.1%.

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Precision orbit determination with SLR observations considering range bias estimation

  • Kim, Young-Rok;Park, Sang-Young;Park, Eun-Seo;Park, Jong-Uk;Jo, Jung-Hyun;Park, Jang-Hyun
    • Bulletin of the Korean Space Science Society
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    • 2010.04a
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    • pp.27.5-28
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    • 2010
  • The unexpected observation condition or insufficient measurement modeling can lead to uncertain measurement errors. The uncertain measurement error of orbit determination problem typically consists of noise, bias and drift. It must be removed by using a proper estimation process for better orbit accuracy. The estimation of noise and drift is not easy because of their random or unpredictable variation. On the other hand, bias is a constant difference between the mean of the measured values and the true value, so it can be simply removed. In this study, precision orbit determination with SLR observations considering range bias estimation is presented. The Yonsei Laser-ranging Precision Orbit Determination System (YLPODS) and SLR NP (Normal Point) observations of CHAMP satellite are used for this work. The SLR residual test is performed to estimate the range bias of each arc. The result shows that we can get better orbit accuracy through range bias estimation.

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Protoflight Model Development of Retroreflector Array for STSAT-2 (과학기술위성2호 레이저반사경의 준비행모델 개발)

  • Lee, Sang-Hyun;Kim, Kyung-Hee;Lee, Jun-Ho;Jin, Jong-Han;Kim, Hyung-Myung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.12
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    • pp.1135-1142
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    • 2007
  • STSAT-2 has an on-board satellite retroreflector array for precise orbit determination. Satellite retroreflector array reflects photon emitted from laser and uses to determine precisely the distance from ground station to satellite by the round-trip travel time of photon. The retroreflector array of protoflight model has been developed and verified through environmental tests. This paper describes the protoflight model of retroreflector array and reports environmental test results. The environmental tests of protoflight model retroreflector array were performed successfully without damage of corner cube prism occurred in engineering model development.

Link Budget Analysis of Laser Retroreflector Array for KOMPSAT-5 (다목적실용위성5호 레이저반사경의 Link Budget 분석)

  • Lee, Sang-Hyun;Kim, Kyung-Hee;Lee, Jun-Ho;Jin, Jong-Han;Lim, Hyung-Chul;Park, Jong-Uk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.1
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    • pp.92-99
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    • 2008
  • KOMSAT-5 will attach an laser retroreflector array for precise orbit determination. Laser retroreflector array was developed by DFZ in Germany and have pyramid type composed of four corner cube prisms. In this paper, the performance analyses as effective area of retroreflector and photons measured by link budget and position of ground station were performed.

Development of Optical System for ARGO-M

  • Nah, Jakyoung;Jang, Jung-Guen;Jang, Bi-Ho;Han, In-Woo;Han, Jeong-Yeol;Park, Kwijong;Lim, Hyung-Chul;Yu, Sung-Yeol;Park, Eunseo;Seo, Yoon-Kyung;Moon, Il-Kwon;Choi, Byung-Kyu;Na, Eunjoo;Nam, Uk-Won
    • Journal of Astronomy and Space Sciences
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    • v.30 no.1
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    • pp.49-58
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    • 2013
  • ARGO-M is a satellite laser ranging (SLR) system developed by the Korea Astronomy and Space Science Institute with the consideration of mobility and daytime and nighttime satellite observation. The ARGO-M optical system consists of 40 cm receiving telescope, 10 cm transmitting telescope, and detecting optics. For the development of ARGO-M optical system, the structural analysis was performed with regard to the optics and optomechanics design and the optical components. To ensure the optical performance, the quality was tested at the level of parts using the laser interferometer and ultra-high-precision measuring instruments. The assembly and alignment of ARGO-M optical system were conducted at an auto-collimation facility. As the transmission and reception are separated in the ARGO-M optical system, the pointing alignment between the transmitting telescope and receiving telescope is critical for precise target pointing. Thus, the alignment using the ground target and the radiant point observation of transmitting laser beam was carried out, and the lines of sight for the two telescopes were aligned within the required pointing precision. This paper describes the design, structural analysis, manufacture and assembly of parts, and entire process related with the alignment for the ARGO-M optical system.

Estimation of Sejong VLBI IVP Point Using Coordinates of Reflective Targets with Their Measurement Errors (반사타겟 좌표 및 오차정보를 이용한 세종 VLBI IVP 위치계산)

  • Hong, Chang-Ki;Bae, Tae-Suk;Yi, Sangoh
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.38 no.6
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    • pp.717-723
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    • 2020
  • Determination of local tie vectors between the space geodetic techniques such as VLBI (Very Long Baseline Interferometer), SLR (Satellite Laser Ranging), DORIS (Doppler Orbit determination and Radiopositioning Integrated on Satellite), GNSS (Global Navigation Satellite System) is essential for combination of ITRF (International Terrestrial Reference Frame). Therefore, it is required to compute IVP (Invariant Point) position of each space geodetic technique with high accuracy. In this study, we have computed Sejong VLBI IVP position by using updated mathematical model for adjustment computation so that the improvement on efficiency and reliability in computation are obtained. The measurements used for this study are the coordinates of reflective targets on the VLBI antenna and their accuracies are set to 1.5 mm for each component. The results show that the position of VLBI IVP together with its standard deviation is successfully estimated when they are compared with those of the results from previous study. However, it is notable that additional terrestrial surveying should be performed so that realistic measurement errors are incorporated in the adjustment computation process.

A Study on the Structural Integrity of Transportable Heavy-duty Tracking-mount (이동형 대하중 추적 마운트의 구조 건전성에 대한 연구)

  • Kim, Byung In;Son, Young Soo;Park, Cheol Hoon;Lee, Sung Hwi;Ham, Sang Yong;Jo, Sang Hyun
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.5
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    • pp.879-885
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    • 2013
  • Satellites provide a lot of information and essay roles in the areas of defense and space observations. The precise distances to the satellites are measured by emitting and retro-reflecting a laser. For such surveys, satellite laser ranging (SLR) systems have been developed in different forms and for different areas. The structural integrity of the tracking mount is essential for it to be able to track a high-speed satellite precisely, overcoming the various external and internal disturbances and operating conditions. In this study, the analysis of a tracking mount was performed for weight, wind loads, and inertia loads in order to verify its soundness. The results of the comparison between aluminum and steel were analyzed in order to select the optimal material for the fork and main housing part. In addition, the natural frequency and mode shape were predicted. Optimal material selection and structural integrity will also be verified using static analysis.

레이저 추적시스템의 원시자료 후처리 및 정규점 산출 연구

  • Seo, Yun-Gyeong;Ryu, Dong-Yeong;Jo, Jung-Hyeon;Kirchner, Georg;Im, Hong-Seo;Park, In-Gwan;Im, Hyeong-Cheol;Park, Jong-Uk
    • Bulletin of the Korean Space Science Society
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    • 2009.10a
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    • pp.42.1-42.1
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    • 2009
  • 한국천문연구원은 우주측지용 레이저 추적 시스템 개발 사업 중 현재 이동형 시스템(ARGO-M) 1기를 개발 중에 있으며, 2009년 5월에 시스템 개념 설계 검토(SDR) 회의를 수행하였고 현재는 예비 설계 단계를 진행 중이다. ARGO-M을 구성하는 5개의 서브시스템 중 하나인 운영시스템은 레이저 관측에 필요한 각종 서브시스템을 제어하고 환경을 종합 판단 후 이를 관측에 반영하며, 실제 관측을 통해 획득한 데이터를 통합 처리 및 전송하는 역할을 담당하고 있다. 현재 본격적인 예비 설계 수행 단계에 있는 운영시스템은 우선적으로 핵심이 되는 소프트웨어의 설계를 위해 오스트리아의 Graz에 위치한 IWF(Institut fur Weltraumforschung) 소속 SLR(Satellite Laser Ranging) 관측소를 2009년도에 방문하여 운영 전반에 관련한 소프트웨어의 로직분석 작업을 수행하였다. Graz 운영시스템 중 소프트웨어관련 시스템은 크게 KHz급 반복율을 가진 레이저를 사용하여 위성까지의 거리 측정에 해당되는 실시간 시스템과 실시간 측정을 통해 저장된 관측 원시 자료를 이후 분석을 수행하는 비 실시간(Non-real time) 시스템으로 나눌 수 있다. 이 중에서 비 실시간 시스템은 원시 자료 분석을 통해 시간 및 거리 바이어스 적용, 노이즈 제거 등의 후처리 과정과 다양한 통계 분석 그리고 SLR시스템의 최종 산출물인 정규점(Normal Point) 생성 등을 수행한다. 이번 소프트웨어 분석 연구를 통해 얻어진 주요 알고리즘과 다양한 다이어그램을 포함한 결과물은 ARGO-M 운영시스템에 최적화하도록 소프트웨어 재구성 및 개발에 반영할 예정이다.

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