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SPACECRAFT TRACKING

SPACECRAFT TRACKING. Lucia Plank. VLBI for space applications (1). Navigation Deep space navigation Routinely done (NASA, ESA) Sensitive perpendicular to line of sight Lunar missions SELENE, Chang‘e Frame ties Optical ↔ radio frequencies Kinematic ↔ dynamic ( ephemerides )

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SPACECRAFT TRACKING

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  1. SPACECRAFT TRACKING Lucia Plank

  2. VLBI forspaceapplications (1) • Navigation • Deepspacenavigation • Routinelydone (NASA, ESA) • Sensitive perpendiculartoline ofsight • Lunar missions • SELENE, Chang‘e • Frame ties • Optical ↔radiofrequencies • Kinematic↔dynamic (ephemerides) • Localties • Co-location in space • GNSS, GRASP, MicroGEM,… VieVS User Workshop 2011

  3. VLBI forspaceapplications (2) • Differential VLBI (D-VLBI) • Quasar – spacecraft (SC) • Deepspacenavigation • DSN, ΔDOR • NASA, ESA • SC – SC • multi-frequencymethod • same beam method • e.g. SELENE (JAXA) • Satellite VLBI • Chang‘e-1 • Tracking of GNSS satellites • Tracking ofothersatellites VieVS User Workshop 2011

  4. VLBI forspaceapplications (3) • Technical realizationisstronglymission-dependent. • Differential vs. Single • Signal structure • Phase vs. Group delay • Receivingsystem But: • Promising recent & futuremissions • Betteraccuracy, smallantennas,… • Technical development • VLBI transmittersaspayload • twin-telescopesoffernew observingmodes • Strong requestfor inter- techniqueties • Co-location in space • GRASP, GNSS, Micro-GEM,… Possibleobservingmodewith 2 twintelescopes VieVS User Workshop 2011

  5. Spacecraft Trackingwith VieVS (1) SPACECRAFT VLBI • curvedwave front • fast movingsources • time ofemission t0 GEODETIC VLBI • plane wave front • stablesources VieVS User Workshop 2011

  6. Spacecraft Trackingwith VieVS (2) 3 experiments: Same beam differential VLBI datafrom Selene providedby NAOJ Mizusawa 1 2 • Chang‘e-1 VLBItracking in single-mode providedby SHAO & BACC 3 Tracking of GNSS satelliteswith VLBI • in cooperationwith V. Tornatore VieVS User Workshop 2011

  7. 1. SELENE • differential (D-) VLBI data • same beam, phasedelay • manyeffectsarethe same forτRSTARandτVSTAR Δτ = τRSTAR – τVSTAR VieVS User Workshop 2011

  8. D-VLBI delay model • Fukushima & Sekido, 2006: • “A VLBI delay model forradiosourcesat finite distance“ • Light time iteration • Pseudo directionvector • Correctionterm VieVS User Workshop 2011

  9. VLBI tracking “single” • Observe GLONASS satelliteswith VLBI • Tornatore et al., 2010 • Single source VLBI • Delay model: • Klioner, 1991 (GCRS) for GNSS • Fukushima & SekidoforChang‘e • Simulationsperformed: • Vie_sim • Parameter: • Partial: • Vie_lsm: • e. g. effectofmeasurementerror on estimatedposition VieVS User Workshop 2011

  10. Summary and outlook • Wesuccessfullyused VieVS to model delaysofspace VLBI applications; weimplemented • Selene same beam dataprocessing • Chang‘e-1 VLBI trackingdataprocessing • Glonass GNSS observations • Vie_lsm was adaptedtoestimatespacecraftpositionsandcanbeusedforsimulations • TO DO: • Verifydelay model asrealized in VieVS • Continueworkwith real data • ImplementVieVS_SCto VieVS_1d VieVS User Workshop 2011

  11. THE END Thank You for listening! lucia.plank@tuwien.ac.at References: Kikuchi et al., 2009: Pico-second accuracy VLBI of the two sub-satellites of SELENE (KAGUYA) using multi-frequency and same-beam methods, Radio Sci. 44(RS2008). Klioner, 1991: General relativistic model of VLBI observables. In: Carter WE (eds) Proceedings of AGU Chapman conference on geodetic VLBI: monitoring of global change. NOAA Technical Report NOS 137 NGS 49, AGU, Washington DC, pp 188-202. Sekido & Fukushima, 2006: A VLBI delay model for radio sources at a finite distance, J. Of Geodesy, 80:137-149, DOI 10.1007/s00190-006-0035-y. Tornatore et al., 2010: Planning of an Experiment for VLBI Tracking of GNSS Satellites, D. Behrend and K. D. Baver (eds), IVS2010 GM Proceedings, VLBI2010: From Vision to Reality.

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