Modern Mars' geomorphological activity, driven by wind, frost, and gravity

Abstract

Extensive evidence of landform-scale martian geomorphic changes has been acquired in the last decade, and the number and range of examples of surface activity have increased as more high-resolution imagery has been acquired. Within the present-day Mars climate, wind and frost/ice are the dominant drivers, resulting in large avalanches of material down icy, rocky, or sandy slopes; sediment transport leading to many scales of aeolian bedforms and erosion; pits of various forms and patterned ground; and substrate material carved out from under subliming ice slabs. Due to the ability to collect correlated observations of surface activity and new landforms with relevant environmental conditions with spacecraft on or around Mars, studies of martian geomorphologic activity are uniquely positioned to directly test surface-atmosphere interaction and landform formation/evolution models outside of Earth. In this paper, we outline currently observed and interpreted surface activity occurring within the modern Mars environment, and tie this activity to wind, seasonal surface CO2 frost/ice, sublimation of subsurface water ice, and/or gravity drivers. Open questions regarding these processes are outlined, and then measurements needed for answering these questions are identified. In the final sections, we discuss how many of these martian processes and landforms may provide useful analogs for conditions and processes active on other planetary surfaces, with an emphasis on those that stretch the bounds of terrestrial-based models or that lack terrestrial analogs. In these ways, modern Mars presents a natural and powerful comparative planetology base case for studies of Solar System surface processes, beyond or instead of Earth.

Gardening of the Martian Regolith by Diurnal CO2 Frost and the Formation of Slope Streaks

“…Such recurring mechanical alteration of the regolith has been proposed as a process maintaining mobile dust available for lifting (Piqueux et al, 2016), contributing to impact the global climate over long periods of time (Mischna & Piqueux, 2020). Similar conclusions can been drawn when translucent ice forms on (or within) the Martian regolith: at sunrise, the solar energy is deposited at the base of the transparent frost layer, at the interface with the regolith grains, and not at the very atmosphere/ground interface (see the abundant literature on the topic for the polar regions; Diniega et al, 2013Diniega et al, , 2021Hansen et al, 2010Hansen et al, , 2013Pilorget & Forget, 2015;Pilorget et al, 2011Pilorget et al, , 2013Piqueux et al, 2003Piqueux et al, , 2016Pommerol et al, 2011Pommerol et al, , 2013Portyankina et al, 2010Portyankina et al, , 2012Thomas et al, 2010). Basal sublimation yields winds internal to the very surficial regolith and has the potential to disturb the upper regolith.…”

“…The sublimation of seasonal carbon dioxide frost has been associated with numerous processes shaping the surface of Mars (Diniega et al., 2013, 2021; Dundas, 2020; Dundas et al., 2012; Hansen et al., 2013; Pilorget & Forget, 2015; Piqueux et al., 2003, 2008). Similarly, we propose to quantitatively describe the interaction between the sublimating diurnal CO 2 frost and the surface layer.…”

“…The seasonal transfer of CO 2 between the atmosphere and the surface at high latitudes is associated with a wide range of exotic processes shaping the surface morphology (Diniega et al., 2013, 2021; Dundas et al., 2012; Hansen et al., 2013; Pilorget & Forget, 2015; Piqueux & Christensen, 2008; Piqueux et al., 2003), the composition of the atmosphere (Sprague et al., 2004, 2007), impacting the global climate and weather (Haberle, 1979; Haberle et al., 1979; Hourdin et al., 1993), and possibly degrading the near‐surface climate record stored in the polar‐layered deposits (Kieffer, 2007; Kieffer et al., 2006). In contrast, the existence and ubiquity of a diurnal CO 2 cycle at midlatitude and low latitude have only recently been exposed (Khuller, Christensen, Harrison, & Diniega, 2021; Piqueux et al., 2016).…”

The dynamic atmospheric and aeolian environment of Jezero crater, Mars

“…Aeolian processes—the motion of surface sand and the lofting and redistribution of surface dust—are the primary causes of change to the Martian surface and atmosphere in the modern era ( 1 , 2 ). Large dust storms drastically alter atmospheric temperatures, densities, and circulation, presenting hazards to robotic and human missions, but atmospheric dust is also present year-round, impeding visibility and solar power ( 3 , 4 ).…”

Active Mars: A Dynamic World

“…This in turn may mean that more of the ancient and recent Martian geologic record can be explained without dramatic climate change.This work presents a comprehensive summary and categorization of the many types of observed changes on the Martian surface. Aeolian and frost-related surface activity are discussed in more detail in a parallel review by Diniega et al (2021), which focuses on connecting specific landforms to their formative processes; the focus herein is to provide a broad overview of known types of changes in surface morphology and albedo. Weather and seasonal frost and ice are not discussed in detail here, except where necessary to describe their effects on the surface; observations of the atmosphere were reviewed by M. D. Smith (2008) and Martínez et al (2017), and seasonal frost is discussed in Piqueux, Kleinböhl, et al (2015) and references therein.…”