The Huygens Doppler Wind Experiment is designed to determine the
velocity of Titan's zonal winds.
The wind is measured over a height range from 0 - 160 km from its
Doppler signature on the Probe's radio relay signal to the
Cassini Orbiter.
The stringent frequency stability required for the DWE measurement
is assured by
(a) generating the transmitted signal with a externally supplied
ultrastable oscillator (TUSO), and
(b) providing the receiver with an identical ultrastable
external oscillator (RUSO).
Information on probe dynamics (spin rate, spin phase,
parachute swing) and large-scale turbulence in the Titan atmosphere
are secondary objectives of the investigation.
The reconstructed probe trajectory using DWE data provides
the best estimate of Huygens' final place of rest on Titan.
This paper presents results of a research project partially funded
by the Deutsche Agentur für Raumfahrtangelegenheiten (DARA) GmbH
under contract 50 OH 9207.
The responsibility for the contents is assumed by the authors.
Allison, M 1992, A preliminary assessment of the Titan
planetary boundary layer, in Symposium on Titan, ESA SP-338,
113-118.
Allison, M, Del Genio, A D & Zhou, W 1994, Zero potential
vorticity envelopes for the zonal-mean velocity of the Venus/Titan
atmospheres, J. Atmos. Sci. 51, 694-702.
Atkinson, D H 1989, Measurement of planetary wind fields by
Doppler monitoring of an atmospheric entry vehicle,
Ph.D. Thesis, Washington State University, Pullman WA, 609 pp.
Atkinson, D H, Pollack J B & Seiff A 1990, Measurement of a
zonal wind profile on Titan by Doppler tracking of the Cassini entry
probe, Radio Sci. 25, 865-882.
Bird, M K 1995, Atmospheric attenuation of the Huygens S-Band
Radio Signal during the Titan Descent, in Huygens: Science Payload
and Mission, ESA-SP 1177 (this volume).
Coustenis, A 1990, Spatial variations of temperature and
composition in Titan's atmosphere: Recent results,
Ann. Geophysicae 8, 645-652.
Del Genio, A D, Zhou, W & Eichler, T P 1993, Equatorial
superrotation in a slowly rotating GCM: Implications for Titan
and Venus, Icarus 101, 1-17.
Flasar, F M, Allison M & Lunine, J I 1995, Huygens Probe wind
drift: science issues and recommendations, in Huygens: Science
Payload and Mission, ESA-SP 1177 (this volume).
Flasar, F M & Conrath, B J 1990, Titan's stratospheric
temperatures: A case for dynamical inertia?, Icarus 85,
346-354.
Flasar, F M, Samuelson, R E & Conrath, B J 1981, Titan's
atmosphere: temperature and dynamics, Nature 292,
693-698.
Flury, W 1986, Cassini Mission - Titan Probe trajectory in
The Solid Bodies of the Outer Solar System,
ESA-SP 242, 237-281.
Hanel, R et al. 1981, Infrared observations of
the Saturnian system from Voyager 1, Science
212, 192-200.
Hinson, D P & Tyler, G L 1983, Internal gravity waves in
Titan's atmosphere observed by Voyager radio occultation,
Icarus 54, 337-352.
Hourdin, F, Le Van P, Talagrand, O, Courtin, R, Gautier, D &
McKay, C P 1992, Numerical simulation of the circulation
of the atmosphere of Titan, in Symposium on Titan, ESA SP-338,
101-106.
Hubbard, W B et al. 1993, The occultation of 28 Sgr
by Titan, Astron. Astrophys. 269, 541-563.
Lebreton, J-P 1995, Huygens science overview and mission
description, in Huygens: Science Payload and Mission, ESA-SP
1177 (this volume).
Lellouch, E, Coustenis, A, Gautier, D, Raulin, F,
Dubouloz, N, and Frère, C 1989, Titan's atmosphere and hypothesized
ocean: a reanalysis of the Voyager 1 radio-occultation and
IRIS 7.7-m data, Icarus 79, 328-349.
Lindal, G F, Wood, G E, Holtz, H B, Sweetnam, D N, Eshleman V R
& Tyler G L 1983, The atmosphere of Titan: An analysis of the
Voyager 1 radio occultation measurements, Icarus
53, 348-363.
Ott, S 1991, Analysis of targetting requirements for the
Huygens mission, ESTEC Working Paper EWP-1640, 156pp.
Pollack, J B, Atkinson, D H, Seiff, A & Anderson, J D 1992,
Retrieval of a wind profile from the Galileo Probe telemetry signal,
Space Sci. Rev. 60, 143-178.
Smith, P H, Karkoschka, E & Lemmon, M 1992, Titan's North-South
asymmetry from HST images, Bull. Am. Astron. Soc. 24,
950.
Smith, P H, Lemmon, M T, Lorenz, R D, Sromovsky L R, Caldwell J J,
& Allison, M D 1995, Titan's surface, revealed by HST imaging,
Icarus (in press).
Smith, P H, Lemmon, M T, Caldwell J J, Allison, M D, &
Sromovsky L R 1994, HST imaging of Titan, Bull. Am. Astron.\
Soc. 26, 1181.
Strobel, D F & Sicardy, B, 1995, Wind shear and wind
gust models, in Huygens: Science Payload and Mission,
ESA-SP 1177 (this volume).
Toon, O B, McKay, C P, Courtin, R & Ackerman, T P 1988,
Methane rain on Titan, Icarus 75, 255-284.
Tyler, G L, Eshleman, V R, Anderson, J D, Levy, G S, Lindal, G F,
Wood, G E & Croft T A 1981, Radio science investigations of the
Saturn system with Voyager 1: Preliminary results, Science
212, 201-206.