New Dated Craters On Mars And The Moon: Studies Of The Freshest Craters In The Solar System

Persistent Link:
http://hdl.handle.net/10150/337303
Title:
New Dated Craters On Mars And The Moon: Studies Of The Freshest Craters In The Solar System
Author:
Daubar, Ingrid Justine
Issue Date:
2014
Publisher:
The University of Arizona.
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.
Abstract:
New, dated impacts discovered on Mars and the Moon provide direct observations of modern bombardment in the inner Solar System and the freshest available examples of recent craters. Their population, morphology, formation and modification processes relate to issues with secondaries and help calibrate cratering chronology models. I use a subset of the new impacts to measure the current production function at Mars. The resulting production function is a factor of approximately four lower than widely-used models, and the size frequency distribution has a shallower slope. This discrepancy between the measured current impact flux and model predictions could be due to many issues, so craters <~50m diameter should not be used for crater age dating unless the uncertainties are understood. I find that these new martian craters are only slightly deeper on average than the expected depth/diameter ratio (d/D) of ~0.2 for simple primaries; the majority would not be mistaken for secondaries based on d/D. A wide spread in d/D indicates that impact conditions or target properties might influence final crater morphologies at these sizes. Extended low-albedo features surround these new craters, presumed to have formed when the impact blast disturbed a surface coating of high-albedo dust, exposing a darker substrate. Some of these features changed drastically over a few Mars years, however, half of the sites show no changes at all. Estimated fading lifetimes cluster around ~7 Mars years. Controls on the amount and rates of fading have yet to be determined. These results show that the current impact production function is not under-sampling new impacts due to fading prior to detection. New craters have also been discovered on the Moon, using similar techniques. Five new impact craters were found that formed within the last ~40 years. Conclusions are unreliable with only these scant statistics, but preliminary comparisons indicate they follow the expected size frequency distribution predicted by the Neukum [1983; Neukum et al., 2001] production function and chronology. This also leads to a very preliminary measurement of the current Moon/Mars cratering ratio at a single diameter, which falls below models by only a factor of approximately six.
Type:
text; Electronic Dissertation
Keywords:
Cratering; Craters; Impacts; Mars; Moon; Planetary Sciences; Chronology
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Planetary Sciences
Degree Grantor:
University of Arizona
Advisor:
McEwan, Alfred

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleNew Dated Craters On Mars And The Moon: Studies Of The Freshest Craters In The Solar Systemen_US
dc.creatorDaubar, Ingrid Justineen_US
dc.contributor.authorDaubar, Ingrid Justineen_US
dc.date.issued2014-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © 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.en_US
dc.description.abstractNew, dated impacts discovered on Mars and the Moon provide direct observations of modern bombardment in the inner Solar System and the freshest available examples of recent craters. Their population, morphology, formation and modification processes relate to issues with secondaries and help calibrate cratering chronology models. I use a subset of the new impacts to measure the current production function at Mars. The resulting production function is a factor of approximately four lower than widely-used models, and the size frequency distribution has a shallower slope. This discrepancy between the measured current impact flux and model predictions could be due to many issues, so craters <~50m diameter should not be used for crater age dating unless the uncertainties are understood. I find that these new martian craters are only slightly deeper on average than the expected depth/diameter ratio (d/D) of ~0.2 for simple primaries; the majority would not be mistaken for secondaries based on d/D. A wide spread in d/D indicates that impact conditions or target properties might influence final crater morphologies at these sizes. Extended low-albedo features surround these new craters, presumed to have formed when the impact blast disturbed a surface coating of high-albedo dust, exposing a darker substrate. Some of these features changed drastically over a few Mars years, however, half of the sites show no changes at all. Estimated fading lifetimes cluster around ~7 Mars years. Controls on the amount and rates of fading have yet to be determined. These results show that the current impact production function is not under-sampling new impacts due to fading prior to detection. New craters have also been discovered on the Moon, using similar techniques. Five new impact craters were found that formed within the last ~40 years. Conclusions are unreliable with only these scant statistics, but preliminary comparisons indicate they follow the expected size frequency distribution predicted by the Neukum [1983; Neukum et al., 2001] production function and chronology. This also leads to a very preliminary measurement of the current Moon/Mars cratering ratio at a single diameter, which falls below models by only a factor of approximately six.en_US
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectCrateringen_US
dc.subjectCratersen_US
dc.subjectImpactsen_US
dc.subjectMarsen_US
dc.subjectMoonen_US
dc.subjectPlanetary Sciencesen_US
dc.subjectChronologyen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMcEwan, Alfreden_US
dc.contributor.committeememberMcEwan, Alfreden_US
dc.contributor.committeememberByrne, Shaneen_US
dc.contributor.committeememberSwindle, Timen_US
dc.contributor.committeememberBaker, Vicen_US
dc.contributor.committeememberHamilton, Christopheren_US
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