Persistent Link:
http://hdl.handle.net/10150/186644
Title:
Delivery of meteorites from the asteroid belt.
Author:
Nolan, Michael Craig.
Issue Date:
1994
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 process of the delivery of meteorites to the surface of the Earth from plausible source regions such as the asteroid belt is currently understood in general terms, but important uncertainties and conflicts remain to be resolved. Stochastic effects of the rare disruptions of large asteroids on the population of meteorite-sized Earth-crossing asteroids can change the flux and the proportions of compositional types in the infalling meteorite population. These changes can be significant in magnitude over timescales of 10⁸ years. Changes of the order of 1% can be expected on timescales of 10⁵-10⁶ y, consistent with small differences between the Antarctic meteorites and modern falls. The magnitude of changes depends strongly on poorly-understood details of collisions. Asteroids 951 Gaspra and 243 Ida were recently imaged by the Galileo spacecraft. I use a numerical hydrocode model to examine the outcomes of various size impacts into targets the sizes of these asteroids. A shock wave fractures the asteroid in advance of crater excavation flow; thus, for impactors larger than 100 m, impacting at 5.3 km s⁻¹, tensile strength is unimportant in these bodies, whether they are initially intact or are "rubble piles". Because of the shock-induced fracture, impact results are controlled by gravity. Therefore these asteroids are much more resistant to catastrophic disruption than predicted by previous estimates, which had assumed that strength was controlling these processes for rock targets. Fracture of km-size asteroids is different from fracture in terrestrial experiments using few-cm targets. The composition distribution of delivered meteorites depends on the outcomes of such asteroid impacts.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Geophysics.; Astrophysics.
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.titleDelivery of meteorites from the asteroid belt.en_US
dc.creatorNolan, Michael Craig.en_US
dc.contributor.authorNolan, Michael Craig.en_US
dc.date.issued1994en_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 process of the delivery of meteorites to the surface of the Earth from plausible source regions such as the asteroid belt is currently understood in general terms, but important uncertainties and conflicts remain to be resolved. Stochastic effects of the rare disruptions of large asteroids on the population of meteorite-sized Earth-crossing asteroids can change the flux and the proportions of compositional types in the infalling meteorite population. These changes can be significant in magnitude over timescales of 10⁸ years. Changes of the order of 1% can be expected on timescales of 10⁵-10⁶ y, consistent with small differences between the Antarctic meteorites and modern falls. The magnitude of changes depends strongly on poorly-understood details of collisions. Asteroids 951 Gaspra and 243 Ida were recently imaged by the Galileo spacecraft. I use a numerical hydrocode model to examine the outcomes of various size impacts into targets the sizes of these asteroids. A shock wave fractures the asteroid in advance of crater excavation flow; thus, for impactors larger than 100 m, impacting at 5.3 km s⁻¹, tensile strength is unimportant in these bodies, whether they are initially intact or are "rubble piles". Because of the shock-induced fracture, impact results are controlled by gravity. Therefore these asteroids are much more resistant to catastrophic disruption than predicted by previous estimates, which had assumed that strength was controlling these processes for rock targets. Fracture of km-size asteroids is different from fracture in terrestrial experiments using few-cm targets. The composition distribution of delivered meteorites depends on the outcomes of such asteroid impacts.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectGeophysics.en_US
dc.subjectAstrophysics.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.committeememberLunine, Jonathan I.en_US
dc.contributor.committeememberMelosh, H. Jayen_US
dc.contributor.committeememberDenton, M. Bonneren_US
dc.contributor.committeememberEnemark, John H.en_US
dc.identifier.proquest9424977en_US
dc.identifier.oclc722490379en_US
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