• Title/Summary/Keyword: satellite station-keeping

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COMMUNICATIONS SATELLITE SYSTEM BY USING MOON ORBIT SATELLITE CONSTELLATION

  • Lee, Sang-Uk;Kim, Jae-Hoon;Lee, Seong-Pal
    • Journal of Astronomy and Space Sciences
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    • v.20 no.4
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    • pp.313-318
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    • 2003
  • A communications satellite system placed in three-Lagrange points, $L_3$, $L_4$ and $L_5$, of the restricted three-body problem in Earth-Moon system is proposed in this paper. LEO satellite constellation has been another choice of communications system. The proposed system which is alternatives of limited geostationary orbit resources, has some weak points such as long distance from the Earth, relatively expensive launch cost, long delay time, more required power, and so on. It has good points like less efforts (fuel) for station keeping, less eclipses, etc. This system has limitations for applications to provide commercial services but it is still some attractive points.

A Study on Plume Disturbance Calculation Method of GEO-KOMPSAT-2 Satellite (정지궤도 복합위성 플룸 외란 계산 기법 연구)

  • Kang, Wooyong;Chae, Jongwon;Park, Youngwoong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.2
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    • pp.165-171
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    • 2016
  • The attitude control, station keeping and wheel off-loading at GEO-KOMPSAT-2 are realized by thrusters firings. Thrusters 1, 2 and 3 are mounted on the same axis as the solar array, which generates the plume disturbance largely. Therefore the effect of plume disturbance should be analyzed from satellite design phase. In this paper, we described the calculation method of plume disturbance and analyzed the plume disturbance of thruster 1,2 and 3 using GEO-KOMPSAT-2 initial configuration.

NORTH/SOUTH STATION KEEPING OF GEOSTATIONARY SATELLITE USING MFT (MFT 기법을 이용한 정지위성의 남/북 위치보존)

  • 안웅영;김천휘;박봉규
    • Journal of Astronomy and Space Sciences
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    • v.14 no.1
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    • pp.150-157
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    • 1997
  • A precise determination of the fuel efficiency is important because North/South station keeping, which controls the inclination of the geostationary orbit, consumes most of the satellie fuel. We estimate the amount of fuel required during the lifetime of the KOREASAT when MFT(Minimum Fuel Target) technique is adopted, and the result is compared to those when MCT(Maximum Compensation Target) and TBCT(Track-Back Chord Target) technique are applied. From this computation, we find that if MFT technique is adopted, the lifetime of the satellite can be extended at least 45 and 15 days, respectively, compared to those consumed with MCT and TBCT technique.

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COMS BIPROPELLANT PROPULSION SYSTEM (COMS 특별세션)

  • Han, Cho-Young;Park, Eung-Sik;Baek, Myung-Jin;Lee, Ho-Hyung
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.41-44
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    • 2007
  • Korea Aerospace Research Institute (KARI) has jointly developed a bipropellant propulsion system for Communication, Ocean and Meteorological Satellite (COMS) with EADS Astrium in UK. The technology relevant to a bipropellant propulsion system is quite new one in Korea, which is transferred for the first time, with development of COMS propulsion system. It hasn't ever attempted before, and hasn't got any general idea itself as well, in Korea. The COMS Chemical Propulsion System (CPS) is designed to perform both the orbital injection function, to take the spacecraft from transfer orbit to Geostationary Earth Orbit (GEO), and all on-station propulsive functions throughout the lifetime of the satellite. All station keeping manoeuvres are performed using the CPS. The design, manufacture and testing of COMS CPS are addressed in this paper. Feasibility of COMS CPS applicable to the other advanced mission is investigated as well.

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Operational Status of 20mN class Ion Engine Subsystem for ETS-VIII

  • Ozaki, Toshiyuki;Kasai, Yukikazu;Nakagawa, Takafumi;Kajiwara, Kenichi;Ikeda, Masafumi
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.511-518
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    • 2008
  • The Engineering Test Satellite VIII(ETS-VIII) of Japan Aerospace Exploration Agency(JAXA) uses a 20mN class xenon ion engine subsystem(IES) for North-South Station Keeping(NSSK). The IES was modified for a larger satellite with longer lifetime based on the former IES. ETS-VIII, a three-ton class geosynchronous satellite with 10 years bus lifetime, was launched 18 Dec. 2006 JST; it reached the planned orbit and all bus systems were checked out. The IES showed good results and is now under normal operation. The total accumulated operation time of the IES in orbit was about 2300 hours till $19^{th}$ Dec. 2007.

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Operational Validation of the COMS Satellite Ground Control System during the First Three Months of In-Orbit Test Operations (발사 후 3개월간의 궤도 내 시험을 통한 통신해양기상위성 관제시스템의 운용검증)

  • Lee, Byoung-Sun;Kim, In-Jun;Lee, Soo-Jeon;Hwang, Yoo-La;Jung, Won-Chan;Kim, Jae-Hoon;Kim, Hae-Yeon;Lee, Hoon-Hee;Lee, Sang-Cherl;Cho, Young-Min;Kim, Bang-Yeop
    • Journal of Satellite, Information and Communications
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    • v.6 no.1
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    • pp.37-44
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    • 2011
  • COMS(Chollian) satellite which was launched on June 26, 2010 has three payloads for Ka-band communications, geostationary ocean color imaging and meteorological imaging. In order to make efficient use of the geostationary satellite, a concept of mission operations has been considered from the beginning of the satellite ground control system development. COMS satellite mission operations are classified by daily, weekly, monthly, and seasonal operations. Daily satellite operations include mission planning, command planning and transmission, telemetry processing and analysis, ranging and orbit determination, ephemeris and event prediction, and wheel off-loading set point parameter calculation. As a weekly operation, North-South station keeping maneuver and East-West station keeping maneuver should be performed on Tuesday and Thursday, respectively. Spacecraft oscillator updating parameter should be calculated and uploaded once a month. Eclipse operations should be performed during a vernal equinox and autumnal equinox season. In this paper, operational validations of the major functions in COMS SGCS are presented for the first three month of in-orbit test operations. All of the major functions have been successfully verified and the COMS SGCS will be used for the mission operations of the COMS satellite for 7 years of mission life time and even more.

INTRODUCTION OF AOCS HARDWARE CONFIGURATION FOR COMS

  • Park, Young-Woong;Park, Keun-Joo;Lee, Hoon-Hee;Ju, Gwang-Hyeok
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.207-210
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    • 2007
  • A part of the big differences between LEO(Low Earth Orbit) and GEO(Geostationary Earth Orbit) satellite is that transfer orbit is used or not or what tolerance of the position on the mission orbit is permitted. That is to say, the transfer orbit is not used and the constraint of orbit position is not adapted on LEO satellite. Whereas for GEO satellite case, the transfer orbit shall be used due to the very high altitude and the satellite shall be stayed in the station keeping box which is permitted on the mission orbit. These phases are functions for AOCS mission. The aim of this paper is to introduce the AOCS hardware configuration for COMS (Communication, Ocean and Meteorological Satellite). The AOCS hardware of COMS consist of 3 Linear Analogue Sun Sensors (LIASS), 3 Bi-Axis Sun Sensors (BASS), 2 Infra-Red Earth Sensors (IRES), 3 Fiber Optical Gyroscopes (FOG), 5 momentum wheels and 14 thrusters. In this paper, each component is explained how to be used, how to locate and what relation between the AOCS algorithm and these components.

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Orbit Determination of GEO-KOMPSAT-2A Geostationary Satellite (천리안위성 2A호 지구정지궤도위성 궤도결정)

  • Yongrae Kim;Sang-Cherl Lee;Jeongrae Kim
    • Journal of Positioning, Navigation, and Timing
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    • v.13 no.2
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    • pp.199-206
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    • 2024
  • The GEO-KOMPSAT-2A (GK2A) satellite, which was launched in December 2018, carries weather observation payloads and uses the image navigation and registration system to calibrate the observation images. The calibration system requires accurate orbit prediction data and depends on the accuracy of the orbit determination accuracy. In order to find a possible way to improve the current orbit determination accuracy of the GK2A flight dynamic subsystem module, orbit determination software was developed to independently evaluate the orbit determination accuracy. A comprehensive satellite dynamic model is applied for a batch-type least squares filter. When determining the orbit, thrust firing during station-keeping maneuvers and wheel-off loading maneuvers is taken into account. One month of GK2A ranging data were processed to estimate the satellite position on a daily basis. The orbit determination error was evaluated by comparing estimates during overlapping estimation intervals.

A REVIEW FOR DEVELOPING THERMODYNAMIC MODEL OF COMS CPS

  • Chae, Jong-Won;Han, Cho-Young;Yang, Koon-Ho
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.179-182
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    • 2007
  • COMS (Communication, Ocean and Meteorological Satellite) is a geosynchronous satellite and has been developing by KARI and Astrium for Ka-band communication, ocean observation and meteorological observation. COMS Chemical Propulsion System (CPS) uses a bipropellant propulsion subsystem, which is applied for transferring COMS from GTO to GEO (mission orbit) and implementing station-keeping manoeuvres. In this paper COMS CPS is briefly introduced for understanding. A few of mathematical thermodynamic modelings of bipropellant propulsion system in literatures are reviewed and authors has studied those models for developing a computer program, which predicts variations of thermodynamic properties such as temperature and pressure histories in the helium pressurant tank, MMH propellant tank and NTO propellant tank during LAE firing and on-orbit manoeuvrings. The CPS thermodynamic model may be used to compute pressurant and propellant masses and to size tank volumes.

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