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. 7 March 2005 2 EP 8.2: DPG, Berlin 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: 1.Huygens descent speed, meridional speed 2.Huygens starting position 3.Cassini position & velocity

3. 7 March 2005 3 EP 8.2: DPG, Berlin Huygens Descent Paths on Titan

4. 7 March 2005 4 EP 8.2: DPG, Berlin DWE Hardware TUSO on Huygens Probe RUSO in Huygens Receiver on Cassini Ultra-stable Oscillators (USOs)

5. 7 March 2005 5 EP 8.2: DPG, Berlin Huygens Doppler: PCO#1 TUSO/RUSO TCXO/TCXO 3 hours

6. 7 March 2005 6 EP 8.2: DPG, Berlin No power!

7. 7 March 2005 7 EP 8.2: DPG, Berlin 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

8. 7 March 2005 8 EP 8.2: DPG, Berlin Huygens Radio Tracking Net 10:18 UTC-GRT12:30 UTC-GRT

9. 7 March 2005 9 EP 8.2: DPG, Berlin Huygens VLBI Network Facility Start UTCStop UTCComment GBT09:31:1012:15:00 DWE: Real time RSR detection VLBA Fort Davis09:31:1013:45:00 VLBA North Liberty09:31:1013:15:00 VLBA Owens Valley09:30:0914:49:14DWE: No nodding – on Titan continuously VLBA Pie Town09:30:1114:15:04DWE: No nodding – on Titan continuously VLBA Los Alamos09:31:1014:00:00 VLBA Brewster09:31:1014:48:00 VLBA Kitt Peak09:31:1014:15:00DWE VLBA Mauna Kea09:31:1016:00:00DWE Parkes12:26:2316:00:00DWE: Real time RSR detection Hobart11:13:1016:00:00 Ceduna10:13:1016:00:00 Mopra10:10:1016:00:00 Kashima09:31:1016:00:00 Shanghai10:01:1016:00:00 Urumqi11:31:1016:00:00Calibration only, no Huygens signal at 2040 MHz ATCA10:01:1016:00:00Calibration only, no Huygens signal at 2040 MHz Onsala19:01:1022:15:00 Wettzell21:46:1022:15:00

10. 7 March 2005 10 EP 8.2: DPG, Berlin GBT Parkes

11. 7 March 2005 11 EP 8.2: DPG, Berlin 10:18:10 UTC-GRT GBT just noise

12. 7 March 2005 12 EP 8.2: DPG, Berlin GBT Huygens! (~ -171 dBm) Flux density  125 Jy 10:18:15 UTC-GRT

13. 7 March 2005 13 EP 8.2: DPG, Berlin Huygens Frequency: GBT + Parkes

14. 7 March 2005 14 EP 8.2: DPG, Berlin Huygens Frequency: GBT + predicts

15. 7 March 2005 15 EP 8.2: DPG, Berlin Huygens Frequency: Parkes + Predicts predicted impact

16. 7 March 2005 16 EP 8.2: DPG, Berlin Parkes: Huygens Impact on Titan

17. 7 March 2005 17 EP 8.2: DPG, Berlin Zonal Wind Retrieval Doppler shift: Error Analysis:

18. 7 March 2005 18 EP 8.2: DPG, Berlin GBT (1) Raw Doppler (2) Only Huygens Motion (3) Huygens Descent Velocity (4) Huygens Horizontal Velocity Doppler Components

19. 7 March 2005 19 EP 8.2: DPG, Berlin

20. 7 March 2005 20 EP 8.2: DPG, Berlin

21. 7 March 2005 21 EP 8.2: DPG, Berlin 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)