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        <identifier>oai:www.ideals.illinois.edu:2142/26175</identifier>
        <datestamp>2023-07-10</datestamp>
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        <thesis xmlns="http://www.ndltd.org/standards/metadata/etdms/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dc="http://purl.org/dc/elements/1.1/" xsi:schemaLocation="http://www.ndltd.org/standards/metadata/etdms/1.1/ http://www.ndltd.org/standards/metadata/etdms/1.1/etdms11.xsd http://purl.org/dc/elements/1.1/ http://www.ndltd.org/standards/metadata/etdms/1.1/etdmsdc.xsd">
          <dc:contributor>Chung, Soon-Jo</dc:contributor>
          <dc:creator>Morgan, Daniel J.</dc:creator>
          <dc:date>2011-08-25T22:17:22Z</dc:date>
          <dc:date>2011-08-25T22:17:22Z</dc:date>
          <dc:date>2011-08-25T22:17:22Z</dc:date>
          <dc:date>2011-08</dc:date>
          <dc:description>This thesis presents several new open-loop guidance methods for spacecraft swarms comprised of
hundreds to thousands of agents with each spacecraft having modest capabilities. These methods have
three main goals: preventing relative drift of the swarm, preventing collisions within the swarm,
and minimizing the fuel used throughout the mission. The development of these methods progresses
by eliminating drift using the Hill-Clohessy-Wiltshire equations, removing drift due to nonlinearity,
and minimizing the $J_2$ drift. In order to verify these guidance methods, a new dynamic model for the
relative motion of spacecraft is developed. These dynamics are
exact and include the two main disturbances for spacecraft in Low Earth Orbit (LEO), $J_2$ and atmospheric
drag. Using this dynamic model, numerical simulations are provided at each step to show the
effectiveness of each method and to see where improvements can be made. The main result is a
set of initial conditions for each spacecraft in the swarm which provides hundreds of collision-free
orbits in the presence of $J_2$. Finally, a multi-burn strategy is developed in order to provide
hundreds of collision free orbits under the influence of atmospheric drag. This last method works by
enforcing the initial conditions multiple times throughout the mission thereby providing collision free
motion for the duration of the mission.</dc:description>
          <dc:description>Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2011-07-19T19:03:54Z
Item was in collections:
University of Illinois Theses &amp; Dissertations (ID: 1)
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          <dc:identifier>http://hdl.handle.net/2142/26175</dc:identifier>
          <dc:language>en</dc:language>
          <dc:rights>Copyright 2011 Daniel J. Morgan</dc:rights>
          <dc:subject>J2 invariance</dc:subject>
          <dc:subject>swarm keeping</dc:subject>
          <dc:subject>collision free motion</dc:subject>
          <dc:subject>swarm</dc:subject>
          <dc:title>Swarm keeping strategies for spacecraft under J2 and atmospheric drag perturbations</dc:title>
          <degree>
            <department>Aerospace Engineering</department>
            <departmentCode>1615</departmentCode>
            <discipline>Aerospace Engineering</discipline>
            <disciplineCode>4048</disciplineCode>
            <grantor>University of Illinois at Urbana-Champaign</grantor>
            <level>Thesis</level>
            <name>M.S.</name>
            <program>MS: Aerospace Engr -UIUC</program>
            <programCode>10KS4048MS</programCode>
          </degree>
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