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Formulation of a wind specification for Titan late polar summer exploration

Lorenz, Ralph D. and Newman, Claire E. and Tokano, Tetsuya and Mitchell, Jonathan L. and Charnay, Benjamin and Lebonnois, Sebastien and Achterberg, Richard K. (2012) Formulation of a wind specification for Titan late polar summer exploration. Planetary and Space Science, 70 (1). pp. 73-83. ISSN 0032-0633. doi:10.1016/j.pss.2012.05.015.

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Titan’s polar regions, and its hydrocarbon lakes in particular, are of interest for future exploration. The polar conditions have considerable seasonal variation and are distinct from the equatorial environment experienced by Huygens. Thus specific environmental models are required for these regions. This paper, informed by Cassini and groundbased observations and four independent Global Circulation Models (GCMs), summarizes northern summer polar conditions (specifically, regions north of 65°N, during the 2023–2024 period, or solar longitude L_s∼150º–170°) and presents a simple analytical formulation of expected, minimum and maximum winds as a function of altitude to aid spacecraft and instrument design for future exploration, with particular reference to the descent dispersions of the Titan Mare Explorer (TiME) mission concept presently under development. We also consider winds on the surface, noting that these (of relevance for impact conditions, for waves, and for wind-driven drift of a floating capsule) are weaker than those in the lowest cell in most GCMs: some previously-reported estimates of ‘surface’ wind speeds (actually at 90–500 m altitude) should be reduced by 20–35% to refer to the standard 10 m ‘anemometer height’ applicable for surface phenomena. A Weibull distribution with scale speed C=0.4 m/s and shape parameter k=2.0 embraces the GCM-predicted surface wind speeds.

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Lorenz, Ralph D.0000-0001-8528-4644
Additional Information:© 2012 Elsevier Ltd. Received 12 March 2012. Received in revised form 13 May 2012. Accepted 25 May 2012. Available online 6 June 2012. R. Lorenz was supported for this work by APL internal funds, and by the NASA Discovery program (Titan Mare Explorer Phase A study). C. Newman acknowledges the support of the NASA Outer Planets Research Program and access to the NASA Ames High End Computing facility, on which all simulations were performed. We thank Mark Johnson and Bill Willcockson of Lockheed Martin Space Systems for discussions on the influence of descent winds on landing footprints. We thank F. M. Flasar and another (anonymous) reviewer for useful comments on the model and the paper.
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APL internal fundsUNSPECIFIED
NASA Outer Planets Research ProgramUNSPECIFIED
Subject Keywords:Titan; Winds; Atmospheric boundary layer; Spacecraft mission design
Issue or Number:1
Record Number:CaltechAUTHORS:20121030-141331692
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Official Citation:Ralph D. Lorenz, Claire E. Newman, Tetsuya Tokano, Jonathan L. Mitchell, Benjamin Charnay, Sebastien Lebonnois, Richard K. Achterberg, Formulation of a wind specification for Titan late polar summer exploration, Planetary and Space Science, Volume 70, Issue 1, September 2012, Pages 73-83, ISSN 0032-0633, 10.1016/j.pss.2012.05.015. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35184
Deposited By: Ruth Sustaita
Deposited On:30 Oct 2012 21:42
Last Modified:09 Nov 2021 23:13

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