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

Chojnacki, M.; Fenton, L. K.

doi:10.1002/2017je005455

Cited by 5 publications

(5 citation statements)

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“…We briefly review the major published results and their implications, organized by the motivating goals. Additionally, Chojnacki and Fenton [2017] provide a commentary on the full Bagnold Special Issue paper suite.…”

Section: Key Results In This Special Issuementioning

confidence: 99%

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

Bridges

Ehlmann

2018

JGR Planets

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The Bagnold dunes in Gale Crater, Mars, are the first active aeolian dune field explored in situ on another planet. The Curiosity rover visited the Bagnold dune field to understand modern winds, aeolian processes, rates, and structures; to determine dune material composition, provenance, and the extent and type of compositional sorting; and to collect knowledge that informs the interpretation of past aeolian processes that are preserved in the Martian sedimentary rock record. The Curiosity rover conducted a coordinated campaign of activities lasting 4 months, interspersed with other rover activities, and employing all of the rover's science instruments and several engineering capabilities. Described in 13 manuscripts and summarized here, the major findings of the Bagnold Dunes Campaign, Phase I, include the following: the characterization of and explanation for a distinctive, meter‐scale size of sinuous aeolian bedform formed in the high kinetic viscosity regime of Mars' thin atmosphere; articulation and evaluation of a grain splash model that successfully explains the occurrence of saltation even at wind speeds below the fluid threshold; determination of the dune sands' basaltic mineralogy and crystal chemistry in comparison with other soils and sedimentary rocks; and characterization of chemically distinctive volatile reservoirs in sand‐sized versus dust‐sized fractions of Mars soil, including two volatile‐bearing types of amorphous phases.

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Section: Key Results In This Special Issuementioning

confidence: 99%

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

Bridges

Ehlmann

2018

JGR Planets

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“…Phase 1 of the Bagnold Dunes campaign resulted in 14 publications, including 11 manuscripts that were published in a special issue of the Journal of Geophysical Research-Planets (Bridges & Ehlmann, 2018;Chojnacki & Fenton, 2017). Continued exploration of the dunes through Phase 2 of the campaign resulted in the publication of 12 more papers (including this overview), 11 of which are presented in this special collection (Table S3).…”

Section: Key Resultsmentioning

confidence: 99%

Curiosity's Investigation of the Bagnold Dunes, Gale Crater: Overview of the Two‐Phase Scientific Campaign and Introduction to the Special Collection

Lapôtre

Rampe

2018

Geophysical Research Letters

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Between November 2015 and April 2017, Curiosity performed the first in situ investigation of an extraterrestrial dune field-the active Bagnold Dunes of Gale crater, Mars. The campaign consisted of two phases: Phase 1 occurred in southern fall/winter at Namib and High Dunes, two barchan dunes along the trailing edge of the dune field; Phase 2 occurred in southern summer at the Nathan Bridges Dune, a linear dune, and Mount Desert Island, a ripple field along the southern margin of the dune field. Both phases included a suite of observations and measurements that bear significance to our understanding of modern winds, associated sand fluxes, bedform morphology, and physical properties, composition, provenance, and sorting of eolian materials. Altogether, results described in a total of 26 manuscripts (11 of which are presented in this special collection) define the current understanding of Martian eolian processes at subdune scales, complementing previous orbiter-based studies that encompassed larger scales.

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“…Very large ripples elsewhere were encountered by the MER rover at Gusev crater, and by the MSL rover while exploring the Bagnold dunes, but these encounters were limited in some important respects: (1) Although the MER encounter at Gusev crater had the advantage of the rover driving several meters directly into the ripple field (Figure 2a), the rover could not stay long to collect comprehensive data, because oncoming winter compelled the solar‐powered vehicle to move toward steeply sloping terrain elsewhere that would allow optimal orientation of the vehicle's solar panels to enable vehicle survival (Arvidson et al, 2008). (2) At Gale crater, the MSL rover encountered very large ripples several times while traversing between the Bagnold dunes (Bridges & Ehlmann, 2018; Chojnacki & Fenton, 2017; Lapotre & Rampe, 2018) but the Bagnold dunes were too hazardous to drive onto or across; instead, rover explorations were restricted to dune margins and small sandy patches in interdune areas (Figure 5a). Consequently, the MSL rover's arm‐mounted instruments never reached crests of representative very large ripples on any of the main dunes (Appendix ).…”

Section: Msl Rover Observations and Interpretationsmentioning

confidence: 99%

“…Journal of Geophysical Research: Planets winter compelled the solar-powered vehicle to move toward steeply sloping terrain elsewhere that would allow optimal orientation of the vehicle's solar panels to enable vehicle survival (Arvidson et al, 2008). (2) At Gale crater, the MSL rover encountered very large ripples several times while traversing between the Bagnold dunes (Bridges & Ehlmann, 2018;Chojnacki & Fenton, 2017;Lapotre & Rampe, 2018) but the Bagnold dunes were too hazardous to drive onto or across; instead, rover explorations were restricted to dune margins and small sandy patches in interdune areas (Figure 5a). Consequently, the MSL rover's arm-mounted instruments never reached crests of representative very large ripples on any of the main dunes (Appendix C).…”

Section: 1029/2020je006485mentioning

confidence: 99%

A Broad Continuum of Aeolian Impact Ripple Morphologies on Mars is Enabled by Low Wind Dynamic Pressures

et al. 2020

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Aeolian ripples are common in sandy environments on Earth and Mars. On Earth, ripples in sorted dune sands typically are <1 cm high and are erased in high winds. On Mars in similar sands, ripple wavelengths commonly exceed 2 m, with much smaller ripples superimposed. Large Martian ripple sizes and juxtaposition of multiple wavelengths have raised questions about origins and the applicability of terrestrial aeolian physics to different planetary environments. Here, two hypotheses are evaluated for large Martian ripples: (1) fluid/wind drag, analogous to ripples formed under water on Earth, as proposed previously for Martian large ripples; and (2) saltation impact splash, the mechanism creating aeolian ripples of much smaller size on Earth. This study evaluates these hypotheses with numerical experiments and Mars rover observations, and concludes that large Martian ripples develop through the saltation impact splash mechanism. The low-density Martian atmosphere enables aeolian impact ripples to grow much higher into the boundary layer before reaching maximum heights constrained by wind dynamic pressure effects at crests. In this concept, boundary layer conditions influence mature ripple heights more directly than wavelengths. On Mars, low wind dynamic pressures, combined with the impact splash mechanism, also help to explain other distinctively Martian aeolian bedforms, including large longitudinal ripples observed by rovers and orbiters, and transverse aeolian ridges (TARs) distributed widely across the Martian surface. Compared with Earth, low wind dynamic pressures on Mars permit a wider range of ripple sizes, relative ages, morphologies, and orientations in close proximity, as displayed in rover observations. Plain Language Summary On Earth, winds drive sand grains downwind in bouncing motions (called "saltation"). Each high-energy bounce also splashes other surface grains shorter distances, and this impact splash process creates small,~10 cm wavelength ripples with heights <1 cm in typical dune sands. On Mars, sands with similar grain sizes form much larger ripples with wavelengths exceeding 2 m, and their origins have been debated. In this study, numerical simulations and Mars rover observations indicate that aeolian impact ripples can grow much larger on Mars than on Earth because the thin Martian atmosphere does not interfere with the upward growth of ripple crests until ripples are much higher (which in turn constrains minimum, but not maximum, ripple wavelengths). In this concept, wind conditions influence mature aeolian ripple heights more directly than ripple wavelengths. This concept also helps explain other, distinctively Martian aeolian features including large longitudinal ripples, and large transverse aeolian ridges (TARs) observed widely across the Martian surface.

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

Cited by 5 publications

References 47 publications

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

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

Curiosity's Investigation of the Bagnold Dunes, Gale Crater: Overview of the Two‐Phase Scientific Campaign and Introduction to the Special Collection

A Broad Continuum of Aeolian Impact Ripple Morphologies on Mars is Enabled by Low Wind Dynamic Pressures

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