Kathleen C. Howell

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The title of this paper is inspired by the work of Poincaré [1890, 1892], who introduced many key dynamical systems methods during his research on celestial mechanics and especially the three body problem. Since then, many researchers have contributed to his legacy by developing and applying these methods to problems in celestial mechanics and, more(More)
The Russian Phobos-Grunt spacecraft originally planned to return a 200 g sample of surface material from Phobos to Earth. Although it was anticipated that this material would mainly be from the body of Phobos, there is a possibility that such a sample may also contain material ejected from the surface of Mars by large impacts. An analysis of this(More)
In low-thrust, gravity-assist trajectory design, two objectives are often equally important: maximization of final spacecraft mass and minimization of time-of-flight. Generally, these objectives are coupled and competing. Designing the trajectory that is best-suited for a mission typically requires a compromise between the objectives. However, optimizing(More)
To expand mission capabilities needed for exploration of the Solar System, optimal lowthrust trajectories must be found. However, low-thrust, multiple gravity-assist trajectories pose significant optimization challenges because of their expansive, multimodal design space. Here, a novel technique is developed for global, low-thrust, interplanetary trajectory(More)
The L1 and L2 libration points have been proposed as gateways granting inexpensive access to interplanetary space. The lunar libration points, in conjunction with the collinear libration points in the Sun-Earth system, may also become primary hubs for future human activities in the Earth’s neighborhood. The associated manifold tubes have been introduced by(More)
Implementation of a 12 th -order Gauss-Lobatto collocation scheme is detailed, including mesh refinement iterations to meet a user-specified error tolerance. The algorithm is robust and efficient, locating path constrained orbits when little information is available regarding the behavior of the solutions. Using a Fourier series control law, the method is(More)
The success of the Genesis spacecraft, as well as the current Artemis mission, continue to generate interest in expanding the trajectory options for future science and exploration goals throughout the solar system. Incorporating multi-body dynamics into the preliminary design can potentially offer flexibility and influence the maneuver costs to achieve(More)
Resonant orbits have been widely employed in mission design for planetary flyby trajectories (JEO) and, more recently, as a source of long-term stability (IBEX). Yet, resonant orbits have not been explored extensively as transfer mechanisms between non-resonant orbits in multi-body systems. To highlight the benefit of employing resonant orbits for transfers(More)
Decentralized control and agent-based modeling techniques are employed to determine optimal spacecraft motion for formations having multifaceted objectives in complex dynamic regimes. Cooperative satellite “agents” share a common objective (high resolution imaging) and simultaneously pursue private goals (minimal fuel usage). An algorithm is developed based(More)
This study examined the effect of color on responses by 20 14- to 17-yr-old learning disabled students in a probation facility to a puzzle assembly task. Prior to the task, one of two randomly constituted groups of 10 viewed a black and white film illustrating a puzzle assembly, the other group viewed an identical film of the puzzle being assembled in(More)