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The Huygens Doppler Wind Experiment: Results from Titan

The Huygens Doppler Wind Experiment: Results from Titan. Michael Bird (Radiostronomisches Institut, Universität Bonn) And the DWE Team. EGU Vienna - April 25, 2005. The DWE Team. M.K. Bird, R. Dutta-Roy, Y. Dzierma

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The Huygens Doppler Wind Experiment: Results from Titan

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  1. The Huygens Doppler Wind Experiment:Results from Titan Michael Bird (Radiostronomisches Institut, Universität Bonn) And the DWE Team EGU Vienna - April 25, 2005

  2. The DWE Team • M.K. Bird, R. Dutta-Roy, Y. Dzierma Radioastronomisches Inst., Univ. Bonn, Auf dem Hügel 71, 53125 Bonn, Germany • M. Allison NASA Goddard Inst. for Space Studies, 2880 Broadway, New York, NY 10025, USA • D.H. Atkinson Dept. of Elec. & Computer Engineering, Univ. of Idaho, Moscow, ID 83844, USA • S.W. Asmar, W.M. Folkner, D.V. Johnston, R.A. Preston Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr, Pasadena, CA 91109, USA • P. Edenhofer Institut für HF-Technik, Universität Bochum, 44780 Bochum, Germany • D. Plettemeier Elektrotechnisches Institut, Technische Univ. Dresden, 01062 Dresden, Germany • G.L. Tyler Center for Radar Astronomy, Stanford University, Stanford, CA 94305, USA • L.I. Gurvits, S.V. Pogrebenko, I.M. Avruch Joint Inst. for VLBI in Europe, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands Huygens DWE

  3. 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 Huygens DWE

  4. DWE Hardware Ultra-stable Oscillators (USOs) • TUSO on Huygens Probe • RUSO in Huygens Receiver on Cassini Huygens DWE

  5. Huygens Signal paths Cassini TCXO TCXO Channel B Huygens Data TCXO RUSO TCXO TUSO Channel A Huygens Probe Huygens Receivers “Channel C” Earth Huygens DWE

  6. 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 Huygens DWE

  7. Huygens Radio Tracking Net GBT VLBA OV PT VLBA KP MK MK Parkes 10:18 UTC-GRT 12:30 UTC-GRT Huygens DWE

  8. Huygens VLBI Network Huygens DWE

  9. GBT Parkes Huygens DWE

  10. 10:18:15 UTC-GRT 10 GBT Huygens! (~ -171 dBm) just noise Flux density  125 Jy Huygens DWE

  11. Huygens Frequency: GBT + Parkes Huygens DWE

  12. Huygens Frequency: GBT + predicts Huygens DWE

  13. Huygens Frequency: Parkes + Predicts predicted impact Huygens DWE

  14. Parkes: Huygens Impact on Titan Huygens DWE

  15. Zonal Wind Retrieval Doppler shift: where = radial velocity between transmitter and receiver Huygens DWE

  16. Doppler Components GBT (1) Raw Doppler (2) Only Huygens Motion (3) Huygens Descent Velocity (4) Huygens Horizontal Velocity Huygens DWE

  17. Zonal Wind Velocity Huygens DWE

  18. Zonal Wind Height Profile Huygens DWE

  19. DWE: Preliminary Results • Zonal winds above boundary layer are PROGRADE • Huygens drifted 3.95º (~175 km) eastward • Low-velocity layer between 60-100 km • Stong positive/negative wind shear • ‘Unexpected’, but evident in some models • Considerable turbulence above 100 km • Near surface winds are weak (~ 1-2 m/s) Huygens DWE

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