Abdelkhalik, Osama Mohamed Omar (2005-12). Orbit design and estimation for surveillance missions using genetic algorithms. Doctoral Dissertation. Thesis uri icon

abstract

  • The problem of observing a given set of Earth target sites within an assigned time frame is examined. Attention is given mainly to visiting these sites as sub-satellite nadir points. Solutions to this problem in the literature require thrusters to continuously maneuver the satellite from one site to another. A natural solution is proposed. A natural solution is a gravitational orbit that enables the spacecraft to satisfy the mission requirements without maneuvering. Optimization of a penalty function is performed to find natural solutions for satellite orbit configurations. This penalty function depends on the mission objectives. Two mission objectives are considered: maximum observation time and maximum resolution. The penalty function poses multi minima and a genetic algorithm technique is used to solve this problem. In the case that there is no one orbit satisfying the mission requirements, a multi-orbit solution is proposed. In a multi-orbit solution, the set of target sites is split into two groups. Then the developed algorithm is used to search for a natural solution for each group. The satellite has to be maneuvered between the two solution orbits. Genetic algorithms are used to find the optimal orbit transfer between the two orbits using impulsive thrusters. A new formulation for solving the orbit maneuver problem using genetic algorithms is developed. The developed formulation searches for a mini mum fuel consumption maneuver and guarantees that the satellite will be transferred exactly to the final orbit even if the solution is non-optimal. The results obtained demonstrate the feasibility of finding natural solutions for many case studies. The problem of the design of suitable satellite constellation for Earth observing applications is addressed. Two cases are considered. The first is the remote sensing missions for a particular region with high frequency and small swath width. The second is the interferometry radar Earth observation missions. In satellite constellations orbit's design, a new set of compatible orbits, called the "Two-way orbits",whose ground track path is a closed-loop trajectory that intersects itself, in some points, with tangent intersections is introduced. Conditions are derived on the orbital elements such that these Two-way Orbits exist and satellites flying in these orbits pass the tangent intersection points at the same time. Finally, the recently proposed concept of observing a space object from onboard a spacecraft using a star tracker is considered. The measurements of the star tracker provide directions to the target in space and do not provide range measurements. Estimation for the orbit of the target space object using the measurements of the star tracker is developed. An observability analysis is performed to derive conditions on the observability of the system states. The Gaussian Least Squares Differential Correction Technique is implemented. The results obtained demonstrate the feasibility of using the measurements of the star tracker to get a good estimate for the target orbit within a period of measurements ranging from about 20 percent to 50 percent of the orbital period depending on the two orbits.
  • The problem of observing a given set of Earth target sites within an assigned time
    frame is examined. Attention is given mainly to visiting these sites as sub-satellite
    nadir points. Solutions to this problem in the literature require thrusters to continuously
    maneuver the satellite from one site to another. A natural solution is proposed.
    A natural solution is a gravitational orbit that enables the spacecraft to satisfy the
    mission requirements without maneuvering. Optimization of a penalty function is
    performed to find natural solutions for satellite orbit configurations. This penalty
    function depends on the mission objectives. Two mission objectives are considered:
    maximum observation time and maximum resolution. The penalty function poses
    multi minima and a genetic algorithm technique is used to solve this problem. In
    the case that there is no one orbit satisfying the mission requirements, a multi-orbit
    solution is proposed. In a multi-orbit solution, the set of target sites is split into
    two groups. Then the developed algorithm is used to search for a natural solution
    for each group. The satellite has to be maneuvered between the two solution orbits.
    Genetic algorithms are used to find the optimal orbit transfer between the two orbits
    using impulsive thrusters. A new formulation for solving the orbit maneuver problem
    using genetic algorithms is developed. The developed formulation searches for a mini mum fuel consumption maneuver and guarantees that the satellite will be transferred
    exactly to the final orbit even if the solution is non-optimal. The results obtained
    demonstrate the feasibility of finding natural solutions for many case studies.
    The problem of the design of suitable satellite constellation for Earth observing
    applications is addressed. Two cases are considered. The first is the remote sensing
    missions for a particular region with high frequency and small swath width. The second
    is the interferometry radar Earth observation missions. In satellite constellations
    orbit's design, a new set of compatible orbits, called the "Two-way orbits",whose
    ground track path is a closed-loop trajectory that intersects itself, in some points,
    with tangent intersections is introduced. Conditions are derived on the orbital elements
    such that these Two-way Orbits exist and satellites flying in these orbits pass
    the tangent intersection points at the same time. Finally, the recently proposed concept
    of observing a space object from onboard a spacecraft using a star tracker is
    considered. The measurements of the star tracker provide directions to the target in
    space and do not provide range measurements. Estimation for the orbit of the target
    space object using the measurements of the star tracker is developed. An observability
    analysis is performed to derive conditions on the observability of the system states.
    The Gaussian Least Squares Differential Correction Technique is implemented. The
    results obtained demonstrate the feasibility of using the measurements of the star
    tracker to get a good estimate for the target orbit within a period of measurements
    ranging from about 20 percent to 50 percent of the orbital period depending on the
    two orbits.

publication date

  • December 2005