The collisional and dynamical evolution of asteroids.

Hdl Handle:
http://hdl.handle.net/10150/187125
Title:
The collisional and dynamical evolution of asteroids.
Author:
Bottke, William Frederick, Jr.
Issue Date:
1995
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:
Understanding asteroid collisional and dynamical evolution necessitates the use of statistical methods, since an asteroid's physical and orbital characteristics are modified throughout its lifetime by collisions and planetary perturbations. Thus, my thesis investigates evolutionary trends for asteroids by calculating and applying parameters such as collision probabilities, impact velocities, and collisional and dynamical lifetimes. I found that previous calculations of collision probabilities between pairs of asteroids on independent Keplerian orbits often yielded inconsistent results. By correcting and improving the formalism, I obtained results which should be accurate for all cases. Applying this formalism, I calculated collision probabilities and impact velocity distributions for single asteroids (e.g. Gaspra, Ida), asteroid populations, and the terrestrial planets with other asteroid populations. These results allowed me to determine asteroid comminution and planetary impact rates. I also examined the dynamical evolution of asteroids, using a modified Monte-Carlo code. The accuracy of these codes are frequently questioned since, for some planetary encounters on tangential orbits, the two-body scattering approximation is inconsistent with numerical integration results. Thus, to verify the validity of Monte-Carlo results in general, I tracked particle-planetary encounters using a new mapping technique to determine the role of distant perturbations. My results show that Monte-Carlo results yield statistically similar results to numerical integration for all but the most pathological cases, and my model shows why. Finally, I used this Monte-Carlo model, modified to include impact disruption, asteroid fragmentation after disruption, and observational selection effects to determine the most likely source for a population of small asteroids near the Earth. My results show that main-belt asteroids (via the 3:1 or v₆ resonances) are an unlikely source for these objects, as are small bodies ejected from Mars after a large cratering event. However, planetary ejecta from either the Earth-Moon system or Venus is dynamically consistent with these orbits. Of these three, the Moon is the most likely source since its escape velocity is significantly lower than either Earth or Venus.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Planetary Sciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Greenberg, Richard

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleThe collisional and dynamical evolution of asteroids.en_US
dc.creatorBottke, William Frederick, Jr.en_US
dc.contributor.authorBottke, William Frederick, Jr.en_US
dc.date.issued1995en_US
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.abstractUnderstanding asteroid collisional and dynamical evolution necessitates the use of statistical methods, since an asteroid's physical and orbital characteristics are modified throughout its lifetime by collisions and planetary perturbations. Thus, my thesis investigates evolutionary trends for asteroids by calculating and applying parameters such as collision probabilities, impact velocities, and collisional and dynamical lifetimes. I found that previous calculations of collision probabilities between pairs of asteroids on independent Keplerian orbits often yielded inconsistent results. By correcting and improving the formalism, I obtained results which should be accurate for all cases. Applying this formalism, I calculated collision probabilities and impact velocity distributions for single asteroids (e.g. Gaspra, Ida), asteroid populations, and the terrestrial planets with other asteroid populations. These results allowed me to determine asteroid comminution and planetary impact rates. I also examined the dynamical evolution of asteroids, using a modified Monte-Carlo code. The accuracy of these codes are frequently questioned since, for some planetary encounters on tangential orbits, the two-body scattering approximation is inconsistent with numerical integration results. Thus, to verify the validity of Monte-Carlo results in general, I tracked particle-planetary encounters using a new mapping technique to determine the role of distant perturbations. My results show that Monte-Carlo results yield statistically similar results to numerical integration for all but the most pathological cases, and my model shows why. Finally, I used this Monte-Carlo model, modified to include impact disruption, asteroid fragmentation after disruption, and observational selection effects to determine the most likely source for a population of small asteroids near the Earth. My results show that main-belt asteroids (via the 3:1 or v₆ resonances) are an unlikely source for these objects, as are small bodies ejected from Mars after a large cratering event. However, planetary ejecta from either the Earth-Moon system or Venus is dynamically consistent with these orbits. Of these three, the Moon is the most likely source since its escape velocity is significantly lower than either Earth or Venus.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairGreenberg, Richarden_US
dc.contributor.committeememberHubbard, William B.en_US
dc.contributor.committeememberChase, Clement G.en_US
dc.contributor.committeememberRichardson, R. M.en_US
dc.identifier.proquest9531143en_US
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