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EP 8.2: DPG, Berlin - March 7, 2005

EP 8.2: DPG, Berlin - March 7, 2005. The Huygens Doppler Wind Experiment: Initial Results. Michael Bird (Radiostronomisches Institut, Universität Bonn) And the DWE Team. DWE Concept. Goal: In situ determination of zonal wind speed along Huygens descent path

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EP 8.2: DPG, Berlin - March 7, 2005

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  1. EP 8.2: DPG, Berlin - March 7, 2005 The Huygens Doppler Wind Experiment: Initial Results Michael Bird (Radiostronomisches Institut, Universität Bonn) And the DWE Team

  2. DWE Concept • Goal: In situ determination of zonal wind speed along Huygens descent path • Approach: Record Doppler effect on Huygens carrier signal => radial velocity • Input parameters: • Huygens descent speed, meridional speed • Huygens starting position • Cassini position & velocity EP 8.2: DPG, Berlin

  3. Huygens Descent Paths on Titan EP 8.2: DPG, Berlin

  4. DWE Hardware Ultra-stable Oscillators (USOs) • TUSO on Huygens Probe • RUSO in Huygens Receiver on Cassini EP 8.2: DPG, Berlin

  5. Huygens Doppler: PCO#1 TUSO/RUSO TCXO/TCXO 3 hours EP 8.2: DPG, Berlin

  6. No power! EP 8.2: DPG, Berlin

  7. DWE from Earth: Geometry • Huygens antenna pointed only ~30° from Earth • Better SNR than for Galileo Probe detection at Jupiter • Probe velocity projection in direction to Earth nearly antiparallel to projection in direction to Orbiter 20º EP 8.2: DPG, Berlin

  8. Huygens Radio Tracking Net 10:18 UTC-GRT 12:30 UTC-GRT EP 8.2: DPG, Berlin

  9. Huygens VLBI Network EP 8.2: DPG, Berlin

  10. GBT Parkes EP 8.2: DPG, Berlin

  11. 10:18:10 UTC-GRT GBT just noise EP 8.2: DPG, Berlin

  12. 10:18:15 UTC-GRT GBT Huygens! (~ -171 dBm) Flux density  125 Jy EP 8.2: DPG, Berlin

  13. Huygens Frequency: GBT + Parkes EP 8.2: DPG, Berlin

  14. Huygens Frequency: GBT + predicts EP 8.2: DPG, Berlin

  15. Huygens Frequency: Parkes + Predicts predicted impact EP 8.2: DPG, Berlin

  16. Parkes: Huygens Impact on Titan EP 8.2: DPG, Berlin

  17. Zonal Wind Retrieval Doppler shift: Error Analysis: EP 8.2: DPG, Berlin

  18. Doppler Components GBT (1) Raw Doppler (2) Only Huygens Motion (3) Huygens Descent Velocity (4) Huygens Horizontal Velocity EP 8.2: DPG, Berlin

  19. EP 8.2: DPG, Berlin

  20. EP 8.2: DPG, Berlin

  21. DWE: Preliminary Results • Zonal winds above boundary layer are PROGRADE • Low-velocity layer between 60-80 km • Stong positive/negative wind shear • ‘Unexpected’, but evident in some GCMs • Considerable turbulence above 100 km • Near surface winds are weak (~ 1-2 m/s) EP 8.2: DPG, Berlin

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