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Martian aeolian activity at the Bagnold Dunes, Gale Crater: The view from the surface and orbit
Author(s) -
Bridges N. T.,
Sullivan R.,
Newman C. E.,
Navarro S.,
Beek J.,
Ewing R. C.,
Ayoub F.,
Silvestro S.,
Gasnault O.,
Le Mouélic S.,
Lapotre M. G. A.,
Rapin W.
Publication year - 2017
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1002/2017je005263
Subject(s) - martian , mars exploration program , geology , aeolian processes , impact crater , martian surface , wind speed , astrobiology , atmosphere of mars , atmospheric sciences , sand dune stabilization , planetary surface , angle of repose , geomorphology , oceanography , physics
The first in situ investigation of an active dune field on another planetary surface occurred in 2015–2016 when the Mars Science Laboratory Curiosity rover investigated the Bagnold Dunes on Mars. High Resolution Imaging Science Experiment images show clear seasonal variations that are in good agreement with atmospheric model predictions of intra‐annual sand flux and migration directions that together indicate that the campaign occurred during a period of low wind activity. Curiosity surface images show that limited changes nevertheless occurred, with movement of large grains, particularly on freshly exposed surfaces, two occurrences of secondary grain flow on the slip face of Namib Dune, and a slump on a freshly exposed surface of a large ripple. These changes are seen at Martian solar day (sol)‐to‐sol time scales. Grains on a rippled sand deposit and unconsolidated dump piles show limited movement of large grains over a few hours during which mean friction speeds are estimated at 0.3–0.4 m s −1 . Overall, the correlation between changes and peak Rover Environmental Monitoring Station (REMS) winds is moderate, with high wind events associated with changes in some cases, but not in others, suggesting that other factors are also at work. The distribution of REMS 1 Hz wind speeds shows a significant tail up to the current 20 m s −1 calibration limit, indicating that even higher speed winds occur. Nonaeolian triggering mechanisms are also possible. The low activity period at the dunes documented by Curiosity provides clues to processes that dominated in the Martian past under conditions of lower obliquity.