Higher-than-predicted saltation threshold wind speeds on Titan

Devon M. Burr, Nathan T. Bridges, John R. Marshall, James Smith, Bruce R. White, Joshua P. Emery

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Titan, the largest satellite of Saturn, exhibits extensive aeolian, that is, wind-formed, dunes1,2, features previously identified exclusively on Earth, Mars and Venus.Wind tunnel data collected under ambient and planetary-analogue conditions inform our models of aeolian processes on the terrestrial planets3,4.However, the accuracy of these widely used formulations in predicting the threshold wind speeds required tomove sand by saltation, or by short bounces, has not been testedunder conditions relevant for non-terrestrial planets. Here we derive saltation threshold wind speeds under the thick-atmosphere, low-gravity and low-sediment-density conditions on Titan, using a high-pressure wind tunnel5 refurbished to simulate the appropriate kinematic viscosity for the near-surface atmosphere of Titan. The experimentally derived saltation threshold wind speeds are higher than those predicted by models based on terrestrial-analogue experiments6,7, indicating the limitations of thesemodels for such extreme conditions. The models can be reconciled with the experimental resultsby inclusion of the extremely lowratio of particle density to fluid density8 on Titan. Whereas the density ratio term enables accurate modelling of aeolian entrainment in thick atmospheres, such as those inferred for some extrasolar planets, our results also indicate that for environments with high density ratios, such as in jets on icy satellites or in tenuous atmospheres or exospheres, the correction for lowdensity-ratio conditions is not required.

Original languageEnglish (US)
Pages (from-to)60-63
Number of pages4
JournalNature
Volume517
Issue number7532
DOIs
StatePublished - Jan 1 2015

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saltation
Titan
wind velocity
atmosphere
planet
eolian process
Saturn
Venus
wind tunnel
entrainment
Mars
viscosity
kinematics
gravity
sand
fluid
sediment
modeling

ASJC Scopus subject areas

  • General

Cite this

Burr, D. M., Bridges, N. T., Marshall, J. R., Smith, J., White, B. R., & Emery, J. P. (2015). Higher-than-predicted saltation threshold wind speeds on Titan. Nature, 517(7532), 60-63. https://doi.org/10.1038/nature14088

Higher-than-predicted saltation threshold wind speeds on Titan. / Burr, Devon M.; Bridges, Nathan T.; Marshall, John R.; Smith, James; White, Bruce R.; Emery, Joshua P.

In: Nature, Vol. 517, No. 7532, 01.01.2015, p. 60-63.

Research output: Contribution to journalArticle

Burr, DM, Bridges, NT, Marshall, JR, Smith, J, White, BR & Emery, JP 2015, 'Higher-than-predicted saltation threshold wind speeds on Titan', Nature, vol. 517, no. 7532, pp. 60-63. https://doi.org/10.1038/nature14088
Burr DM, Bridges NT, Marshall JR, Smith J, White BR, Emery JP. Higher-than-predicted saltation threshold wind speeds on Titan. Nature. 2015 Jan 1;517(7532):60-63. https://doi.org/10.1038/nature14088
Burr, Devon M. ; Bridges, Nathan T. ; Marshall, John R. ; Smith, James ; White, Bruce R. ; Emery, Joshua P. / Higher-than-predicted saltation threshold wind speeds on Titan. In: Nature. 2015 ; Vol. 517, No. 7532. pp. 60-63.
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