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Published byRuth Chadwick Modified about 1 year ago

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아리랑 위성 1 호 (KOMPSAT-1) 궤도 변화와 우주환경 변화 비교 박진영 1,2, 문용재 2, 조경석 2, 김해동 3, 김관혁 2, 김연한 2, 박영득 2, 이유 1 1 충남대학교, 2 한국천문연구원, 3 한국항공우주연구원 한국우주과학회 춘계 학술대회

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Contents 1. Introduction 2. Selection of event by using Solar and Geomagnetic data 3. Analysis of KOMPSAT-1 Drag force data 4. Summary 5. Further work

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Motivation ( 조경석 등 2004) 11/ nT Orbit Prediction Error : about 16km 10/ nT 11/ nT

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Space Environment Variations Sun Coronal Holes Geomagnetic Field Radiation Environment Ionosphere Neutral Atmosphere Density Soft X-ray fluxes Energetic Charged Particles Coronal Mass Ejections EUV fluxes (10.7 cm flux) Effects on Satelites

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Space Environment Variations Sun Coronal Holes Geomagnetic Field Radiation Environment Ionosphere Neutral Atmosphere Density Soft X-ray fluxes Energetic Charged Particles Coronal Mass Ejections EUV fluxes (10.7 cm flux) Effects on Satelites ~ 8 min 2~3 day F10.7 Dst

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Drag acceleration equation a D = ½ C D A/M V r 2 u area/mass ratio drag coefficienttotal density relative velocity direction unit vector a D, C D = program A = 5.871m 2 M = 448kg Vr = 7.5 m/sec 2 Density (Knowles,2001)

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Scale factors and empirical accelerations 1. Computed orbit, integrated from initial state based only on force models

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Scale factors and empirical accelerations 2. Tracking observations (SLR, GPS) do not match the computed orbit

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Scale factors and empirical accelerations 3. The modeled aerodynamic force is multiplied with a scale factor, estimated from the data, so that the computed orbit better matches the observations

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2. The selection of Solar and Geomagnetic Data 1)Geoeffective CME 2)Non-geoeffective CME Weak Flare Strong Flare Sun : X-ray < M-class Earth (Dst) : <-100nT EW E W Sun Sun : X-ray > X-class and East limb CME Flare Geoeffective (Dst < -100) Non- Geoeffective Weak Strong (X-class)

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3.Analysis of KOMPSAT-1 Drag 1) (CME, Dst = -387nT) Dst vs Drag F10.7 vs Drag : -Dst index : Drag : F10.7 index : Drag

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2) ( Strong Flare ) Dst vs DragF10.7 vs Drag : -Dst index : Drag : F10.7 index : Drag

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4) F10.7 vs Drag at delayr 0 day day day day0.83

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3) Dst vs Drag in total data r = 0.6 (0.8)

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5) MSISE-90 density vs Satellite Drag Blue line : MSISE-90 model Black line : Satellite Drag

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6) Estimated & Model density What can be the reason? - Current atmospheric models are statistical and do not allow a short term prediction for a give altitude. (Space Weather Effects Catalogue, ESWS, 2001) MSISE-90 density Real density MSISE-90 density Real density

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4. Summary Satellite Drag and Dst have similar patterns. Satellite Drag started with the solar flare at the same time and then has a peak 1 day later. (the best cross correlation at 1-day time delay prediction of satellite drag ) MSISE-90 model density and Drag also have similar patterns. MSISE-90 do not allow a short term (such as storms) prediction

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5. Further work 1. Investigate more events in long term 2. Examine other factors associated with Satellite Drag ex) Proton flux, AE index, etc 3. Compare the Drag with empirical high atmosphere models such as NRLMSISE-00.

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