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

Abstract

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.

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

“…Curiosity's recent traverse through an active basaltic eolian deposit, informally named the Bagnold Dune Field (Figure ), provided the opportunity for a multi‐instrument investigation of the geomorphology, chemistry, and mineralogy of the dunes. This comprehensive campaign is the first in situ assessment of active dunes on a planet other than Earth [ Bridges and Ehlmann , ].…”

“…The science objectives of the Bagnold Dune Campaign included characterizing sedimentary structures and active dune processes on Mars, constraining the provenance of the dune sand, and assessing the potential of the dunes as a trap for water [ Bridges and Ehlmann , ]. From sols (Mars days) 1164 to 1244, Curiosity completed six campaign phases, including an in situ sampling campaign that was conducted at a site named Gobabeb (Figure ), located on the northwestern flank and secondary slipface of the Namib barchan dune (Figure ).…”

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

“…The study of Martian aeolian bedforms remains a less mature research field compared to that of dunes and ripples on Earth, although the plethora of high‐quality images and other data from Mars missions, especially in the last decade, has substantially increased our understanding. Up until the Bagnold Dune Campaign [ Bridges and Ehlmann , ; also see below], studies relied heavily on orbital imaging, mainly from the High Resolution Imaging Science Experiment (HiRISE) [ McEwen et al , ], and other remote sensing instruments. Martian sand dunes display the full spectrum of terrestrial classes [ Hayward et al , ], likely because the underlying physical parameters controlling morphology, namely, wind direction and intensity, and sand supply, are of sufficient strength and variability that the resulting forms are similar.…”

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

“…Thus, a dedicated campaign (between sols 1181 and 1254) was conducted in order to investigate these dunes. The main objective of this campaign was to acquire chemical, geomorphological, and textural data on these active dunes in order to increase the understanding of past and current aeolian processes on Mars [ Bridges and Ehlmann , ].…”

“…The second step was the detailed investigation of Namib dune. The rover first stopped in front of the main Namib dune slip face to perform remote‐sensing observations, then moved to a secondary slip face in order to perform in situ investigations at a site referred to as “Gobabeb.” The overall Bagnold dune campaign is described in more detail in Bridges and Ehlmann [], and geomorphological observations are presented in Bridges et al . [].…”