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dc.contributor.advisorKluever, Craig A. (Craig Allan)eng
dc.contributor.authorCersosimo, Dario O.eng
dc.date.issued2011eng
dc.date.submitted2011 Springeng
dc.descriptionTitle from PDF of title page (University of Missouri--Columbia, viewed on October 18, 2012).eng
dc.descriptionThe entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.eng
dc.descriptionDissertation advisor: Dr. Craig A. Kluevereng
dc.descriptionVita.eng
dc.descriptionPh. D. University of Missouri--Columbia 2011.eng
dc.description"May 2011"eng
dc.description.abstractThe gravity-tractor (GT) consists of a spacecraft hovering inertially over a small asteroid. This equilibrium state is achieved by the action of a pair of engines that balance the gravitational acceleration. Due to Newton's law of gravitation the spacecraft causes a small gravitational pull on the asteroid that after prolonged time intervals causes a small change in its trajectory preventing it from impacting the Earth. This dissertation introduces a novel concept in the implementation of the GT to augment its deflection merits. Two novel guidance laws are designed to take advantage of the asteroid shape and rotation rate forcing the GT spacecraft to move towards and away the center of mass of the asteroid in synchronous motion with its rotation, resulting in an increased gravitational pull. The asteroid model was generalized as a solid, homogeneous triaxial ellipsoid. A small GT spacecraft was proposed and a detailed model of the NSTAR ion thrusters was used to investigate the efficiency of the GT operating under these novel guidance laws and the classical inertial hovering. The performance of these hovering laws was examined over a wide range of asteroid shapes and rotation rates. The results obtained suggest that it is possible to improve the deflection merits by up to 60%. The propellant efficiency showed to be sensitive to the spacecraft parameters; in particular, the engine model and the controller used to sustain the desired hovering state play an important role in the propellant penalties associated with these extended hovering modes. Furthermore, these results indicate that previous works have overestimated the propellant efficiency of a typical GT by using oversimplified models of solar electric engines.eng
dc.description.bibrefIncludes bibliographical referenceseng
dc.format.extentxii, 102 pageseng
dc.identifier.oclc872560897eng
dc.identifier.urihttps://doi.org/10.32469/10355/15766eng
dc.identifier.urihttps://hdl.handle.net/10355/15766
dc.languageEnglisheng
dc.publisherUniversity of Missouri--Columbiaeng
dc.relation.ispartofcommunityUniversity of Missouri--Columbia. Graduate School. Theses and Dissertations.eng
dc.rightsOpenAccess.eng
dc.rights.licenseThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.
dc.subjectgravity tractoreng
dc.subjectasteroid deflectioneng
dc.subjectlow-push deflection strategieseng
dc.subjectguidance lawseng
dc.titleEvaluation of novel hovering strategies to improve gravity-tractor deflection meritseng
dc.typeThesiseng
thesis.degree.disciplineMechanical and aerospace engineering (MU)eng
thesis.degree.grantorUniversity of Missouri--Columbiaeng
thesis.degree.levelDoctoraleng
thesis.degree.namePh. D.eng


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