Active Mars: A Dynamic World

Abstract

An axiom of geology is that the present is the key to the past. Knowledge of current processes and their consequences is an essential tool for understanding history, including the ancient rock record and the associated climate. Modern Mars is cold, with a thin atmosphere, and has previously been thought to have little ongoing geomorphic activity-especially when compared with ancient Mars, which had apparent largescale, Earth-like processes, as inferred from ancient landforms. This interpretation has led much research to focus not on the present Martian environment, but rather on Mars' early conditions and climate change over time. However, in recent years, observations of ongoing surface changes have proliferated, demonstrating that Mars' landscape is actively evolving and likely has been throughout the Amazonian epoch. These observed geomorphic changes shed light on a variety of active processes, some with no terrestrial analog, and reveal present-day Mars to be 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. Weathering and other microscale or chemical processes are not discussed. Even with these exclusions, the scope of the subject is broad and we have focused on the key discoveries and constraints.Studying surface changes on Mars yields a unique look at processes within an un-Earthly environment.

Diurnal Cycle of Rapid Air Temperature Fluctuations at Jezero Crater: Probability Distributions, Exponential Tails, Scaling, and Intermittency

“…Additionally, Mars ongoing water erosion and seismic or volcanic driven surface alteration are limited. This makes meteoritic impacts and meteorology the main agents forcing and altering the Martian surface for the last millions of years (e.g., Dundas et al., 2021, for a review). The combination of environmental forcing through aeolian erosion, mechanical forcing from wind and pressure fluctuations, or thermodynamical forcing via changes in temperature and atmospheric composition, including water vapor, can cause a range of surface patterns.…”

Wind and Turbulence Observations With the Mars Microphone on Perseverance

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The NASA Perseverance mission searches for signs of past habitable environments in Jezero crater, part of an ancient delta on Mars (Farley et al, 2020;Mangold et al, 2021), as it also prepares for future human exploration. A large part of this search requires the determination of the dynamic processes currently at play on Mars (Dundas et al, 2021). One major contributor of day-to-day surface alteration is through aeolian processes, whereby dust and sand are lofted and transported.

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Detection of Detached Ice-fragments at Martian Polar Scarps Using a Convolutional Neural Network

“…The shape of the detached ice-fragments is an important parameter for estimating the flux and volume of ongoing mass wasting and studying the dynamic evolution of the NPLD scarps. From another perspective, the avalanches have been investigated visually for those fractured NPLD scarps which display ice block fall deposits at their base [7], [63]. We will extend our deep learning method to automatically detect active avalanches, to help reduce human work and complete an automated monitoring pipeline of this area [5], [64].…”

“…Active mass wasting, such as gully activity including erosion and deposition of material [3] and ice block falls [4], [5], [6] can be investigated through change detection. Equatorward-facing steep scarps at the periphery of the martian North Polar Layered Deposits (NPLD) are composed of several-kilometer thick stacks of dusty water ice layers that record martian climate history over millions of years [7]. Due to thermoelastic stresses [8], [9], they experience fracturing that leads to ice block falls [1], [4].…”