Dynamical History of the Asteroid Belt and Implications for Terrestrial Planet Bombardment

Hdl Handle:
http://hdl.handle.net/10150/194083
Title:
Dynamical History of the Asteroid Belt and Implications for Terrestrial Planet Bombardment
Author:
Minton, David A.
Issue Date:
2009
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:
The main asteroid belt spans ~2-4 AU in heliocentric distance and is sparsely populated by rocky debris. The dynamical structure of the main belt records clues to past events in solar system history. Evidence from the structure of the Kuiper belt, an icy debris belt beyond Neptune, suggests that the giant planets were born in a more compact configuration and later experienced planetesimal-driven planet migration. Giant planet migration caused both mean motion and secular resonances to sweep across the main asteroid belt, raising the eccentricity of asteroids into planet-crossing orbits and depleting the belt. I show that the present-day semimajor axis and eccentricity distributions of large main belt asteroids are consistent with excitation and depletion due to resonance sweeping during the epoch of giant planet migration. I also use an analytical model of the sweeping of the &nu;<sub>6</sub> secular resonance, to set limits on the migration speed of Saturn.After planet migration, dynamical chaos became the dominant loss mechanism for asteroids with diameters D>10 km in the current asteroid belt. I find that the dynamical loss history of test particles from this region is well described with a logarithmic decay law. My model suggests that the rate of impacts from large asteroids may have declined by a factor of three over the last ~3 Gy, and that the present-day impact flux of D>10 km objects on the terrestrial planets is roughly an order of magnitude less than estimates used in crater chronologies and impact hazard risk assessments.Finally, I have quantified the change in the solar wind <super>6</super>Li/<super>7</super>Li ratio due to the estimated in-fall of chondritic material and enhanced dust production during the epoch of planetesimal-driven giant planet migration. The solar photosphere is currently highly depleted in lithium relative to chondrites, and <super>6</super>Li is expected to be far less abundant in the sun than <super>7</super>Li due to the different nuclear reaction rates of the two isotopes. Evidence for a short-lived impact cataclysm that affected the entire inner solar system may be found in the composition of implanted solar wind particles in lunar regolith.
Type:
text; Electronic Dissertation
Keywords:
Asteroids; Cratering; Dynamics; Resonances; Solar System
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Planetary Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Malhotra, Renu
Committee Chair:
Malhotra, Renu

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleDynamical History of the Asteroid Belt and Implications for Terrestrial Planet Bombardmenten_US
dc.creatorMinton, David A.en_US
dc.contributor.authorMinton, David A.en_US
dc.date.issued2009en_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.abstractThe main asteroid belt spans ~2-4 AU in heliocentric distance and is sparsely populated by rocky debris. The dynamical structure of the main belt records clues to past events in solar system history. Evidence from the structure of the Kuiper belt, an icy debris belt beyond Neptune, suggests that the giant planets were born in a more compact configuration and later experienced planetesimal-driven planet migration. Giant planet migration caused both mean motion and secular resonances to sweep across the main asteroid belt, raising the eccentricity of asteroids into planet-crossing orbits and depleting the belt. I show that the present-day semimajor axis and eccentricity distributions of large main belt asteroids are consistent with excitation and depletion due to resonance sweeping during the epoch of giant planet migration. I also use an analytical model of the sweeping of the &nu;<sub>6</sub> secular resonance, to set limits on the migration speed of Saturn.After planet migration, dynamical chaos became the dominant loss mechanism for asteroids with diameters D>10 km in the current asteroid belt. I find that the dynamical loss history of test particles from this region is well described with a logarithmic decay law. My model suggests that the rate of impacts from large asteroids may have declined by a factor of three over the last ~3 Gy, and that the present-day impact flux of D>10 km objects on the terrestrial planets is roughly an order of magnitude less than estimates used in crater chronologies and impact hazard risk assessments.Finally, I have quantified the change in the solar wind <super>6</super>Li/<super>7</super>Li ratio due to the estimated in-fall of chondritic material and enhanced dust production during the epoch of planetesimal-driven giant planet migration. The solar photosphere is currently highly depleted in lithium relative to chondrites, and <super>6</super>Li is expected to be far less abundant in the sun than <super>7</super>Li due to the different nuclear reaction rates of the two isotopes. Evidence for a short-lived impact cataclysm that affected the entire inner solar system may be found in the composition of implanted solar wind particles in lunar regolith.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectAsteroidsen_US
dc.subjectCrateringen_US
dc.subjectDynamicsen_US
dc.subjectResonancesen_US
dc.subjectSolar Systemen_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.advisorMalhotra, Renuen_US
dc.contributor.chairMalhotra, Renuen_US
dc.contributor.committeememberMalhotra, Renuen_US
dc.contributor.committeememberStrom, Robert Gen_US
dc.contributor.committeememberGreenberg, Richard Jen_US
dc.contributor.committeememberSwindle, Timothy Den_US
dc.contributor.committeememberByrne, Shaneen_US
dc.identifier.proquest10787en_US
dc.identifier.oclc659753634en_US
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