Investigations of the Bagnold Dune Field, Gale crater

Mars
9 May 2016
20 April 2018
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"Selfie" of Curiosity at the Gobabeb site. Mars Hand Lens Imager (MAHLI) acquired the images used to make this mosaic, processed by Mike Ravine at Malin Space Science Systems (NASA/JPL-Caltech/MSSS).

The Bagnold Dune Field, Gale crater, is a large and active Martian sand deposit. This special issue welcomes publications studying the dunes, utilizing orbital data and/or the full suite of MSL instruments from Curiosity's winter 2015/2016 in situ investigation. Related papers on dunes and sands on Mars that contextualize the Bagnold dune field are also welcome.

This special issue is dedicated to Nathan Bridges, who co-organized the issue and passed away before it was completed.

Manuscripts should be submitted through the GEMS Web site for JGR Planets.

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Table of Contents

Free Access

The Thermophysical Properties of the Bagnold Dunes, Mars: Ground-Truthing Orbital Data

Christopher S. Edwards, Sylvain Piqueux, Victoria E. Hamilton, Robin L. Fergason, Ken E. Herkenhoff, Ashwin R. Vasavada, Kristen A. Bennett, Leah Sacks, Kevin Lewis, Michael D. Smith,
Key Points

  • Thermally derived particle sizes of the Bagnold dunes from orbit and landed assets are consistent with direct particle size measurements
  • Thermally derived particle sizes are not dramatically affected by surface ripples or thin layers of induration/armoring
  • Subpixel mixing of sand with nearby materials likely resulted in overestimated particle sizes in previous orbital measurements

Free Access

Visible/near-infrared spectral diversity from in situ observations of the Bagnold Dune Field sands in Gale Crater, Mars

Jeffrey R. Johnson, Cherie Achilles, James F. Bell III, Steve Bender, Edward Cloutis, Bethany Ehlmann, Abigail Fraeman, Olivier Gasnault, Victoria E. Hamilton, Stéphane Le Mouélic, Sylvestre Maurice, Patrick Pinet, Lucy Thompson, Danika Wellington, Roger C. Wiens,
Key Points

  • Visible/near-infrared spectra of Bagnold Dunes sands indicate variable mixtures of olivine and ferric materials
  • Observed spectral variations with grain size are consistent with laboratory spectra of olivine
  • Coarse-grained fractions enriched in mafic components compared to more ferric, fine fractions, likely related to aeolian/kinematic sorting

Open Access

Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover

M. G. A. Lapotre, B. L. Ehlmann, S. E. Minson, R. E. Arvidson, F. Ayoub, A. A. Fraeman, R. C. Ewing, N. T. Bridges,
Key Points

  • Spectral variability in the dunes arises from spatially variable mineral composition and qualitatively correlates with local sand flux
  • Mineral abundance estimates from orbit are within <13 wt % of in situ measurements from CheMin in average, although uncertainties are large
  • Orbital observations of dune field mineral variations may be explained by both aeolian sorting and mixing of multiple sand sources

Open Access

A probabilistic approach to remote compositional analysis of planetary surfaces

M. G. A. Lapotre, B. L. Ehlmann, S. E. Minson,
Key Points

  • We design and implement a Markov Chain Monte Carlo approach to spectral unmixing to test accuracies of the Hapke radiative transfer model
  • Errors/uncertainties in abundances/grain sizes are quantified for two sets of laboratory ternary mixtures, with and without noise
  • Large uncertainties due to nonunique fits highlight the usefulness of probabilistic approaches to spectral unmixing of remote sensing data

Open Access

Martian aeolian activity at the Bagnold Dunes, Gale Crater: The view from the surface and orbit

N. T. Bridges, R. Sullivan, C. E. Newman, S. Navarro, J. van Beek, R. C. Ewing, F. Ayoub, S. Silvestro, O. Gasnault, S. Le Mouélic, M. G. A. Lapotre, W. Rapin,
Key Points

  • Dune activity observed on the surface of Mars
  • Changes seen from Mars orbit and surface
  • First estimate of wind threshold speeds on Mars in situ

Free Access

APXS-derived chemistry of the Bagnold dune sands: Comparisons with Gale Crater soils and the global Martian average

C. D. O'Connell-Cooper, J. G. Spray, L. M. Thompson, R. Gellert, J. A. Berger, N. I. Boyd, E. D. Desouza, G. M. Perrett, M. Schmidt, S. J. VanBommel,
Key Points

  • Gale soils are compositionally similar to a global basaltic Martian soil but with slight evidence of local contribution
  • The sands of the Bagnold barchan dunes are compositionally distinct with mafic enrichment
  • The active Bagnold sands are low in dust as evidenced by low S, Cl, and Zn concentrations

Open Access

Chemistry, mineralogy, and grain properties at Namib and High dunes, Bagnold dune field, Gale crater, Mars: A synthesis of Curiosity rover observations

B. L. Ehlmann, K. S. Edgett, B. Sutter, C. N. Achilles, M. L. Litvak, M. G. A. Lapotre, R. Sullivan, A. A. Fraeman, R. E. Arvidson, D. F. Blake, N. T. Bridges, P. G. Conrad, A. Cousin, R. T. Downs, T. S. J. Gabriel, R. Gellert, V. E. Hamilton, C. Hardgrove, J. R. Johnson, S. Kuhn, P. R. Mahaffy, S. Maurice, M. McHenry, P.-Y. Meslin, D. W. Ming, M. E. Minitti, J. M. Morookian, R. V. Morris, C. D. O'Connell-Cooper, P. C. Pinet, S. K. Rowland, S. Schröder, K. L. Siebach, N. T. Stein, L. M. Thompson, D. T. Vaniman, A. R. Vasavada, D. F. Wellington, R. C. Wiens, A. S. Yen,
Key Points

  • Because of ongoing aeolian activity, the Bagnold dunes consist of well-sorted sands and lack the finer grains typical of Martian soils
  • Dune sands are chemically distinct with elevated Si, Mg, and Ni and lower H2O, S, and Cl relative to all previously measured Martian fines
  • Two distinct, water-/OH-bearing amorphous components are identified: Fe-, S-, and Cl-rich material in dust and Si-rich material in the sands

Open Access

Mineralogy of an active eolian sediment from the Namib dune, Gale crater, Mars

C. N. Achilles, R. T. Downs, D. W. Ming, E. B. Rampe, R. V. Morris, A. H. Treiman, S. M. Morrison, D. F. Blake, D. T. Vaniman, R. C. Ewing, S. J. Chipera, A. S. Yen, T. F. Bristow, B. L. Ehlmann, R. Gellert, R. M. Hazen, K. V. Fendrich, P. I. Craig, J. P. Grotzinger, D. J. Des Marais, J. D. Farmer, P. C. Sarrazin, J. M. Morookian,
Key Points

  • Gobabeb is dominated by basaltic minerals (~60%) and X-ray amorphous phases (~40%) and likely derives from more than one parent material
  • CheMin-derived crystal chemistry provides insights into the origin(s) and geologic history of the dune material
  • CheMin analyses of Gobabeb confirm inferences of mafic-enriched sands and allow for an evaluation of orbital-based mineralogy estimates

Free Access

Aeolian saltation on Mars at low wind speeds

R. Sullivan, J. F. Kok,
Key Points

  • Numerical experiments show that low wind speeds can initiate and sustain low saltation fluxes on Mars
  • Low flux saltation should produce slow surface changes over long periods, helping to explain observed changes without strong winds
  • Rover observations at Meridiani Planum and Gale crater are consistent with aeolian settings shaped by saltation at low wind speeds

Open Access

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

R. C. Ewing, M. G. A. Lapotre, K. W. Lewis, M. Day, N. Stein, D. M. Rubin, R. Sullivan, S. Banham, M. P. Lamb, N. T. Bridges, S. Gupta, W. W. Fischer,
Key Points

  • Impact ripples, grainfall, and grainflows occur on Martian dunes and are similar to terrestrial counterparts
  • Unique, meter-scale large ripples are found on Martian dunes and would distinguish the Martian and terrestrial eolian rock records
  • The angle of repose on Martian dunes and large ripples is found to be around 29°, which is similar to that found on Earth

Free Access

Geochemistry of the Bagnold dune field as observed by ChemCam and comparison with other aeolian deposits at Gale Crater

Agnes Cousin, Erwin Dehouck, Pierre-Yves Meslin, Olivier Forni, Amy J. Williams, Nathan Stein, Olivier Gasnault, Nathan Bridges, Bethany Ehlmann, Susanne Schröder, Valérie Payré, William Rapin, Patrick Pinet, Violaine Sautter, Nina Lanza, Jérémie Lasue, Sylvestre Maurice, Roger C. Wiens,
Key Points

  • Bagnold Dunes Campaign corresponds to the first in situ characterization of active dune field
  • Bagnold dunes lack <100 μm and > 1mm grains
  • Bagnold dunes are overall similar to Aeolis Palus soils in composition but are depleted in volatile-rich amorphous component and present slightly more olivine

Open Access

The Mars Science Laboratory (MSL) Bagnold Dunes Campaign, Phase I: Overview and introduction to the special issue

Nathan T. Bridges, Bethany L. Ehlmann,
Key Points

  • Curiosity's Bagnold Dunes Campaign, Phase I, was the first in situ exploration of an active extraterrestrial dune field
  • Wind speed, morphology, grain size, mineralogy, and chemistry were measured over 4 months, interspersed with other rover activities
  • Key findings include meter-scale bedforms, saltation at low wind speeds, and particle-size-dependent chemistry, mineralogy, and volatile reservoirs in Martian fines

Free Access

The Geologic Exploration of the Bagnold Dune Field at Gale Crater by the Curiosity Rover

Matthew Chojnacki, Lori K. Fenton,
Key Points

  • This commentary provides a broad overview of the Bagnold dune field Special Issue
  • This first in situ investigation of a dune field on another planet has resulted in a number of discoveries
  • Results and discussion are provided in the context of Mars aeolian science