Abstract
Aeolian processes are believed to play a major role in the landscape evolution of Mars. Investigations on Martian aeolian landforms such as ripples, transverse aeolian ridges (TARs), and dunes, and aeolian sediment flux measurements are important to enhance our understanding of past and present wind regimes, the ongoing dust cycle, landscape evolution, and geochemistry. These aeolian bedforms are often comprised of loose sand and sharply undulating topography and thus pose a threat to mobility and maneuvers of Mars rovers. Here we present a first-hand account of the distribution, morphologies, and morphometrics of TARs in Oxia Planum, the recently selected ExoMars 2020 Rover landing site. The gridded mapping was performed for contiguous stretches of TARs within all the landing ellipses using 57 sub-meter high resolution imaging science experiment (HiRISE) scenes. We also provide the morphological descriptions for all types of TARs present within the landing ellipses. We use HiRISE digital terrain models (DTMs) along with the images to derive morphometric information for TARs in Oxia Planum. In general, the average areal TAR coverage was found to be 5.4% (±4.9% standard deviation), increasing from west to east within the landing ellipses. We report the average TAR morphometrics in the form of crest–ridge width (131.1 ± 106.2 m), down-wind TAR length (17.6 ± 10.1 m), wavelength (37.3 ± 11.6 m), plan view aspect ratio (7.1 ± 2.3), inter-bedform spacing (2.1 ± 1.1), slope (10.6° ± 6.1°), predominant orientations (NE-SW and E-W), and height (1.2 ± 0.8 m). While simple TARs are predominant, we report other TAR morphologies such as forked TAR, wavy TAR with associated smaller secondary ripples, barchan-like TAR, networked TAR, and mini-TARs from the region. Our results can help in planning the rover traverses in terms of both safe passage and scientific returns favoring aeolian research, particularly improving our understanding of TARs.
Highlights
Aeolian processes have played a significant role in landscape evolution and development of surficial features on planets with considerable atmospheres such as Earth, Mars, and Venus [1]
transverse aeolian ridges (TARs) are widespread aeolian landforms on contemporary Mars, but we are yet to be certain of their formation mechanism, age and temporal evolution, composition and geophysics, and their relationship with global sedimentation and climatic evolution
The rover platform is equipped with infrared spectrometers and multispectral imagers, and the provision of a drill with an embedded multispectral camera provides us the opportunity to perform profiling starting from the tougher top layer of TARs and reaching to the supposedly loosely-packed subsurface
Summary
Aeolian processes have played a significant role in landscape evolution and development of surficial features on planets with considerable atmospheres such as Earth, Mars, and Venus [1]. For Mars, the substantial influx of orbiter, lander, and rover imagery and geophysical data with continuously improving resolutions in the past two decades have largely facilitated our understanding of the relict and active aeolian processes and landforms, proving aeolian processes to be one of the dominant surface-modifying agents on Mars [2]. Even though the atmosphere of Mars is considerably thinner (i.e., ~1% of Earth’s), the abundance of such landforms on Mars demonstrates strong atmosphere–lithosphere coupling over a large spatiotemporal domain [10]. These aeolian features and underlying interactions can tell us more about the climate and landscape evolutions on Mars and their presence highlights the regions with past or ongoing sediment transport [11]. Several papers [12,13,14,15] over the past decades have reported on manual or semi-automated mapping of features like ripples and sand dunes on Mars at global and regional scales to help our understanding
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