Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice
Understanding the age and distribution of shallow ice on Mars is valuable for interpreting past and present climate conditions, and has implications on habitability and future in situ resource utilization. Many ice-related features, such as lobate debris aprons and concentric crater fill, have been...
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ftunivarizona:oai:repository.arizona.edu:10150/625594 2023-05-15T18:32:57+02:00 Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice Viola, Donna McEwen, Alfred S. Byrne, Shane Baker, Victor R. Hamilton, Christopher W. Carter, Lynn M. 2017 http://hdl.handle.net/10150/625594 en_US eng The University of Arizona. http://hdl.handle.net/10150/625594 Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. ice impact craters ISRU Mars thermokarst text Electronic Dissertation 2017 ftunivarizona 2020-06-14T08:15:53Z Understanding the age and distribution of shallow ice on Mars is valuable for interpreting past and present climate conditions, and has implications on habitability and future in situ resource utilization. Many ice-related features, such as lobate debris aprons and concentric crater fill, have been studied using a range of remote sensing techniques. Here, I explore the distribution of expanded craters, a form of sublimation thermokarst where shallow, excess ice has been destabilized and sublimated following an impact event. This leads to the collapse of the overlying dry regolith to produce the appearance of diameter widening. The modern presence of these features suggests that excess ice has remained preserved in the terrain immediately surrounding the craters since the time of their formation in order to maintain the surface. High-resolution imagery is ideal for observing thermokarst features, and much of the work described here will utilize data from the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). Expanded craters tend to be found in clusters that emanate radially from at least four primary craters in Arcadia Planitia, and are interpreted as secondary craters that formed nearly simultaneously with their primaries. Crater age dates of the primaries indicate that the expanded secondaries, as well as the ice layer into which they impacted, must be at least tens of millions of years old. Older double-layer ejecta craters in Arcadia Planitia commonly have expanded craters superposed on their ejecta – and they tend to be more expanded (with larger diameters) in the inner ejecta layer. This has implications on the formation mechanisms for craters with this unique ejecta morphology. Finally, I explore the distribution of expanded craters south of Arcadia Planitia and across the southern mid-latitudes, along with scalloped depressions (another form of sublimation thermokarst), in order to identify the modern excess ice boundary in this region and any longitudinal variations. This study identifies some potential low-latitude locations with patchy excess ice, possibly preserved during a past climate. Through these studies, I will infer regions that contain abundant ice today and consider the implications that this ice has on both the martian climate and future exploration. Doctoral or Postdoctoral Thesis Thermokarst The University of Arizona: UA Campus Repository |
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Open Polar |
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The University of Arizona: UA Campus Repository |
op_collection_id |
ftunivarizona |
language |
English |
topic |
ice impact craters ISRU Mars thermokarst |
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ice impact craters ISRU Mars thermokarst Viola, Donna Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
topic_facet |
ice impact craters ISRU Mars thermokarst |
description |
Understanding the age and distribution of shallow ice on Mars is valuable for interpreting past and present climate conditions, and has implications on habitability and future in situ resource utilization. Many ice-related features, such as lobate debris aprons and concentric crater fill, have been studied using a range of remote sensing techniques. Here, I explore the distribution of expanded craters, a form of sublimation thermokarst where shallow, excess ice has been destabilized and sublimated following an impact event. This leads to the collapse of the overlying dry regolith to produce the appearance of diameter widening. The modern presence of these features suggests that excess ice has remained preserved in the terrain immediately surrounding the craters since the time of their formation in order to maintain the surface. High-resolution imagery is ideal for observing thermokarst features, and much of the work described here will utilize data from the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). Expanded craters tend to be found in clusters that emanate radially from at least four primary craters in Arcadia Planitia, and are interpreted as secondary craters that formed nearly simultaneously with their primaries. Crater age dates of the primaries indicate that the expanded secondaries, as well as the ice layer into which they impacted, must be at least tens of millions of years old. Older double-layer ejecta craters in Arcadia Planitia commonly have expanded craters superposed on their ejecta – and they tend to be more expanded (with larger diameters) in the inner ejecta layer. This has implications on the formation mechanisms for craters with this unique ejecta morphology. Finally, I explore the distribution of expanded craters south of Arcadia Planitia and across the southern mid-latitudes, along with scalloped depressions (another form of sublimation thermokarst), in order to identify the modern excess ice boundary in this region and any longitudinal variations. This study identifies some potential low-latitude locations with patchy excess ice, possibly preserved during a past climate. Through these studies, I will infer regions that contain abundant ice today and consider the implications that this ice has on both the martian climate and future exploration. |
author2 |
McEwen, Alfred S. Byrne, Shane Baker, Victor R. Hamilton, Christopher W. Carter, Lynn M. |
format |
Doctoral or Postdoctoral Thesis |
author |
Viola, Donna |
author_facet |
Viola, Donna |
author_sort |
Viola, Donna |
title |
Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
title_short |
Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
title_full |
Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
title_fullStr |
Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
title_full_unstemmed |
Expanded Craters on Mars: Implications for Shallow, Mid-Latitude Excess Ice |
title_sort |
expanded craters on mars: implications for shallow, mid-latitude excess ice |
publisher |
The University of Arizona. |
publishDate |
2017 |
url |
http://hdl.handle.net/10150/625594 |
genre |
Thermokarst |
genre_facet |
Thermokarst |
op_relation |
http://hdl.handle.net/10150/625594 |
op_rights |
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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