Periodic Reporting for period 1 - MGFR (The (missing) fingerprints of Martian large-scale glaciations)
Reporting period: 2021-09-06 to 2023-09-05
The surface of Mars is incised by thousands of valleys, evidence that the red planet harbored surface liquid water ~3.9-3.5 Byr ago, when life emerged on Earth. This climate optimum finished ~3.5-3 Gyr ago, marking the rise of a global hyperarid cryosphere. The transition between the early climate optimum and the current global cryosphere poses a significant question: why is the surface of Mars mostly devoid of glacial landforms? Indeed, liquid water should have remained stable under building glaciers and ice sheets, and there is evidence for liquid water action related to ground ice melt. But landforms characteristic of water-glacier interactions, such as moraines, grooves, or drumlins, are largely missing from Mars’ geological record. This has led scientists to believe that martian ice masses never hosted water underneath, rendering them unable to erode.
However, work on the dynamics of terrestrial warm-based ice masses revealed a feedback between driving stresses and ice sliding. The lower surface gravity on Mars would hinder driving stress, but how this would affect glacial sliding on Mars had not been studied. The main objective of this project was to determine whether Martian glacial masses produce a different geological fingerprint from terrestrial ones. This discrepancy would imply that Martian ancient ice sheets harbored basal water, with implications for our search for water and habitable environments on Mars.
Work follows three driving objectives
(O1) Understanding the link between glacial landforms and underlying glacial dynamics.
(O2) Explain why certain glacial landforms may be missing on Mars.
(O3) Explore the role of martian glaciation through time under the perspective of ice dynamics.
However, work on the dynamics of terrestrial warm-based ice masses revealed a feedback between driving stresses and ice sliding. The lower surface gravity on Mars would hinder driving stress, but how this would affect glacial sliding on Mars had not been studied. The main objective of this project was to determine whether Martian glacial masses produce a different geological fingerprint from terrestrial ones. This discrepancy would imply that Martian ancient ice sheets harbored basal water, with implications for our search for water and habitable environments on Mars.
Work follows three driving objectives
(O1) Understanding the link between glacial landforms and underlying glacial dynamics.
(O2) Explain why certain glacial landforms may be missing on Mars.
(O3) Explore the role of martian glaciation through time under the perspective of ice dynamics.
O1. Terrestrial glacial landscapes differ depending on the characteristics of the former ice cover. Alpine glaciation produces U-shaped valleys and moraines. Ice sheet glaciation is characterized by swaths of lineations and drumlins, terminal moraines, eskers, etc. Polar ice caps, characterized by much thinner and colder ice, may lack obvious fingerprints of glaciation. The result from this first objective is the realization that glacial drainage and the speed of glacial sliding play a key role on the final geomorphology produced by ice cover. Arguments that Mars' lack of certain landforms point unequivocally at the lack of existence of martian warm-based glaciation are unfounded.
O2. I utilized state-of-the-art physical models to describe terrestrial glacial hydrology, and interrogated the dominant subglacial drainage mechanism on Mars: cavities or channels. Glacial sliding, responsible for glacial erosion, builds upon inefficient cavity-based drainage. In this mode, subglacial cavities build up water, which cannot drain and therefore pressurizes. Effective pressure, ice overburden minus subglacial water pressure, tends to zero and localized lift of the ice occurs, increasing glacial sliding velocity. Fast sliding, large driving stresses, and the lack of an efficient drainage system increase sliding velocity. On the other hand, efficient subglacial channelized drainage greatly reduce water pressure. Smaller sliding velocities, smaller driving stresses, and efficient subglacial drainage reduce glacial sliding, and prevent the formation of glacially scoured landscapes, as observed on the Canadian Arctic. When interrogating the effect of the martian gravity on subglacial drainage, and thus the relative importance of glacial sliding, I found that inefficient drainage would have been strongly inhibited on Mars, in favor of efficient networks of subglacial channels. The fingerprints of glaciation on Mars should be eskers and subglacial channels, whereas scouring, moraines, and other sliding landforms should be rare. Results from objectives 1 and 2 were published in Grau Galofre et al., 2022a.
O3 was accomplished in two parts, targetting the early Mars (4-3 Gyr ago) and late Mars period (3Gyr ago to present). I reviewed progress on early Mars glaciations, exploring ancient ice sheet and glacial landforms, their climate and hydrological implications, and connection with subsurface water reservoirs. This work is accepted for publication as a chapter in ‘Ices in the Solar System: ‘Ice on Noachian and Hesperian Mars: Atmospheric, Surface, and Subsurface Processes’ (2024).
Part two aimed at linking ice dynamics and internal structure to surface geomorphology of ice deposits on Mars. For this work I benefited from my participation in the Color and Stereo Surface Imaging System (CaSSIS) to acquire high resolution images of debris-covered glacial deposits. The investigation here considered only the deformation of ice under cold-based conditions, and explored the effect of orbital-induced climatic oscillations on the flow dynamics and surface morphology of the deposit. This work was published in Grau Galofre et al., 2022b.
Results exploitation and dissemination.
Three peer-reviewed publications arise directly from this project, with one more currently nearing submission. Two collaborative efforts were published, one is in review and one nears submission. Dissemination of these results occurred in eight conferences, of which one was at a national level, one was at a European level, and six were international. Additionally, I participated in two CaSSIS team meetings and CaSSIS became science team leader. Public dissemination of results, although somewhat hindered by the language barrier, took place once in the three daylong event ‘Fête de la Science’ to schools and general public.
O2. I utilized state-of-the-art physical models to describe terrestrial glacial hydrology, and interrogated the dominant subglacial drainage mechanism on Mars: cavities or channels. Glacial sliding, responsible for glacial erosion, builds upon inefficient cavity-based drainage. In this mode, subglacial cavities build up water, which cannot drain and therefore pressurizes. Effective pressure, ice overburden minus subglacial water pressure, tends to zero and localized lift of the ice occurs, increasing glacial sliding velocity. Fast sliding, large driving stresses, and the lack of an efficient drainage system increase sliding velocity. On the other hand, efficient subglacial channelized drainage greatly reduce water pressure. Smaller sliding velocities, smaller driving stresses, and efficient subglacial drainage reduce glacial sliding, and prevent the formation of glacially scoured landscapes, as observed on the Canadian Arctic. When interrogating the effect of the martian gravity on subglacial drainage, and thus the relative importance of glacial sliding, I found that inefficient drainage would have been strongly inhibited on Mars, in favor of efficient networks of subglacial channels. The fingerprints of glaciation on Mars should be eskers and subglacial channels, whereas scouring, moraines, and other sliding landforms should be rare. Results from objectives 1 and 2 were published in Grau Galofre et al., 2022a.
O3 was accomplished in two parts, targetting the early Mars (4-3 Gyr ago) and late Mars period (3Gyr ago to present). I reviewed progress on early Mars glaciations, exploring ancient ice sheet and glacial landforms, their climate and hydrological implications, and connection with subsurface water reservoirs. This work is accepted for publication as a chapter in ‘Ices in the Solar System: ‘Ice on Noachian and Hesperian Mars: Atmospheric, Surface, and Subsurface Processes’ (2024).
Part two aimed at linking ice dynamics and internal structure to surface geomorphology of ice deposits on Mars. For this work I benefited from my participation in the Color and Stereo Surface Imaging System (CaSSIS) to acquire high resolution images of debris-covered glacial deposits. The investigation here considered only the deformation of ice under cold-based conditions, and explored the effect of orbital-induced climatic oscillations on the flow dynamics and surface morphology of the deposit. This work was published in Grau Galofre et al., 2022b.
Results exploitation and dissemination.
Three peer-reviewed publications arise directly from this project, with one more currently nearing submission. Two collaborative efforts were published, one is in review and one nears submission. Dissemination of these results occurred in eight conferences, of which one was at a national level, one was at a European level, and six were international. Additionally, I participated in two CaSSIS team meetings and CaSSIS became science team leader. Public dissemination of results, although somewhat hindered by the language barrier, took place once in the three daylong event ‘Fête de la Science’ to schools and general public.
Progress beyond the state of the art. My work opens the door to an understanding of martian glacial landscapes that is physics-based, and not solely based on direct comparison with terrestrial glacial landscapes. My work thus adds a basis to understand how martian glacial landscapes are different from terrestrial, and why.
Expected results until the end of the project. Most results have already been obtained, and the main objective has been explored during the course of this project. I expect the final publication of two other related papers by 2024.
Potential impacts. The timing of water stability on the surface of Mars has long been constrained to the so-called early Mars period, 3.9-3.5 Gyr BP. However, multiple observations of recent landforms indicate that water environments could have persisted much later in Mars’ history, with important astrobiological implications. The impact of my work is in recognizing these environments where water could have been stable under martian ice masses, by recognizing what type of landforms and landsystems are distinctive of such environments on Mars, and how these differ to distinctive landforms of similar environments on Earth. Finally, my work has implications for further understanding the terrestrial glacial hydrology system, with implications for the dynamics of glaciers and glacial drainage under a warming climate.
Expected results until the end of the project. Most results have already been obtained, and the main objective has been explored during the course of this project. I expect the final publication of two other related papers by 2024.
Potential impacts. The timing of water stability on the surface of Mars has long been constrained to the so-called early Mars period, 3.9-3.5 Gyr BP. However, multiple observations of recent landforms indicate that water environments could have persisted much later in Mars’ history, with important astrobiological implications. The impact of my work is in recognizing these environments where water could have been stable under martian ice masses, by recognizing what type of landforms and landsystems are distinctive of such environments on Mars, and how these differ to distinctive landforms of similar environments on Earth. Finally, my work has implications for further understanding the terrestrial glacial hydrology system, with implications for the dynamics of glaciers and glacial drainage under a warming climate.