The Huygens Doppler Wind Experiment: Results from Titan Michael Bird (Radiostronomisches Institut, Universität Bonn) And the DWE Team EGU Vienna - April 25, 2005
Vienna EGU, 25 April Huygens DWE The DWE Team M.K. Bird, R. Dutta-Roy, Y. Dzierma Radioastronomisches Inst., Univ. Bonn, Auf dem Hügel 71, 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, Bochum, Germany D. Plettemeier Elektrotechnisches Institut, Technische Univ. Dresden, 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
Vienna EGU, 25 April Huygens DWE 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
Vienna EGU, 25 April Huygens DWE DWE Hardware TUSO on Huygens Probe RUSO in Huygens Receiver on Cassini Ultra-stable Oscillators (USOs)
Vienna EGU, 25 April Huygens DWE Cassini TCXO RUSO TCXO TUSO Channel B Channel A Earth “Channel C” Huygens Signal paths Huygens Data Huygens Receivers Huygens Probe
Vienna EGU, 25 April Huygens DWE 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
Vienna EGU, 25 April Huygens DWE Huygens Radio Tracking Net 10:18 UTC-GRT12:30 UTC-GRT GBT VLBA MK KP PTOV MK Parkes VLBA
Vienna EGU, 25 April Huygens DWE 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
Vienna EGU, 25 April Huygens DWE GBT Parkes
Vienna EGU, 25 April Huygens DWE GBT Huygens! (~ -171 dBm) Flux density 125 Jy 10:18:15 UTC-GRT 10 just noise
Vienna EGU, 25 April Huygens DWE Huygens Frequency: GBT + Parkes
Vienna EGU, 25 April Huygens DWE Huygens Frequency: GBT + predicts
Vienna EGU, 25 April Huygens DWE Huygens Frequency: Parkes + Predicts predicted impact
Vienna EGU, 25 April Huygens DWE Parkes: Huygens Impact on Titan
Vienna EGU, 25 April Huygens DWE Zonal Wind Retrieval Doppler shift: where = radial velocity between transmitter and receiver
Vienna EGU, 25 April Huygens DWE GBT (1) Raw Doppler (2) Only Huygens Motion (3) Huygens Descent Velocity (4) Huygens Horizontal Velocity Doppler Components
Vienna EGU, 25 April Huygens DWE Zonal Wind Velocity
Vienna EGU, 25 April Huygens DWE Zonal Wind Height Profile
Vienna EGU, 25 April Huygens DWE DWE: Preliminary Results Zonal winds above boundary layer are PROGRADE Huygens drifted 3.95º (~175 km) eastward Low-velocity layer between 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)