Title:
A Study of Variable Thrust, Variable Specific Impulse Trajectories for Solar System Exploration

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dc.contributor.advisor Olds, John R.
dc.contributor.author Sakai, Tadashi en_US
dc.contributor.committeeMember Braun, Robert D.
dc.contributor.committeeMember Johnson, Eric N.
dc.contributor.committeeMember Pritchett, Amy R.
dc.contributor.committeeMember Way, David
dc.contributor.department Aerospace Engineering en_US
dc.date.accessioned 2005-03-01T19:41:30Z
dc.date.available 2005-03-01T19:41:30Z
dc.date.issued 2004-12-07 en_US
dc.description.abstract A study has been performed to determine the advantages and disadvantages of variable thrust and variable specific impulse (Isp) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse, or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: - Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? - If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines, but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 2322537 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/4904
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Interplanetary trajectories en_US
dc.subject Variable Isp engine
dc.subject Numerical analysis
dc.subject Calculus of variations
dc.subject.lcsh Trajectory optimization Computer simulation en_US
dc.subject.lcsh Space vehicles Propulsion systems Computer simulation en_US
dc.title A Study of Variable Thrust, Variable Specific Impulse Trajectories for Solar System Exploration en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename College of Engineering
local.contributor.corporatename Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries Doctor of Philosophy with a Major in Aerospace Engineering
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication f6a932db-1cde-43b5-bcab-bf573da55ed6
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