Evolutionary neurocontrol: A novel method for low-thrust gravity-assist trajectory optimization

This article discusses evolutionary neurocontrol, a novel method for low-thrust gravity-assist trajectory optimization

First and second simulator evaluations of advanced integrated display and control systems

Advanced integrated visual and control systems simulator evaluations for post-Apollo manned spacecraf

Space exploration: The interstellar goal and Titan demonstration

Automated interstellar space exploration is reviewed. The Titan demonstration mission is discussed. Remote sensing and automated modeling are considered. Nuclear electric propulsion, main orbiting spacecraft, lander/rover, subsatellites, atmospheric probes, powered air vehicles, and a surface science network comprise mission component concepts. Machine, intelligence in space exploration is discussed

Incorporation of Mission Design Constraints in Floquet Mode and Hamiltonian Structure-Preserving Orbital Maintenance Control Strategies for Libration Point Orbits

Libration point orbits are, in general, inherently unstable. Without the presence of corrective maneuvers a spacecraft will diverge from the vicinity of such trajectories. In this research effort, two orbital maintenance control strategies are studied: the impulsive Floquet Mode (FM) controller and the continuous Hamiltonian Structure-Preserving (HSP) controller. These two controllers are further developed to incorporate real-world mission design constraints. The FM controller is modified to accommodate feasible maneuver directions that are constrained to a plane or a line. This controller is shown to be applicable for orbital station-keeping of spin stabilized spacecraft that are only equipped with either tangential thrusters or axial thrusters. The HSP controller is extended for application to general three-dimensional hyperbolic libration point orbits, and then discretized to account for the minimum time required for orbit determination and/or scientific operations. Both controllers are applied to an unstable 1 halo orbit in the Sun-Earth/Moon system. The performances of these controllers are examined under the impacts of the spacecraft’s operation errors and mission design constraints. Simulation results suggest that the FM controller is capable of maintaining the motion of the spacecraft in the vicinity of the desired reference trajectory for the duration of the simulation, while satisfying all mission design constraints. The discrete-time MHSP controller proves to be able to improve the stability of the nominal trajectory by reducing the value of the unstable Poincare exponent of the reference orbit

Space transportation system and associated payloads: Glossary, acronyms, and abbreviations

A collection of some of the acronyms and abbreviations now in everyday use in the shuttle world is presented. It is a combination of lists that were prepared at Marshall Space Flight Center and Kennedy and Johnson Space Centers, places where intensive shuttle activities are being carried out. This list is intended as a guide or reference and should not be considered to have the status and sanction of a dictionary

Twenty-first semiannual report to Congress, 1 January - 30 June 1969

Manned space flights, satellite observations, space sciences, and air traffic control - NASA report to Congress for 1 Jan. to 30 June 196

Multi-agent Collision Avoidance Using Interval Analysis and Symbolic Modelling with its Application to the Novel Polycopter

Coordination is fundamental component of autonomy when a system is defined by multiple mobile agents. For unmanned aerial systems (UAS), challenges originate from their low-level systems, such as their flight dynamics, which are often complex. The thesis begins by examining these low-level dynamics in an analysis of several well known UAS using a novel symbolic component-based framework. It is shown how this approach is used effectively to define key model and performance properties necessary of UAS trajectory control. This is demonstrated initially under the context of linear quadratic regulation (LQR) and model predictive control (MPC) of a quadcopter. The symbolic framework is later extended in the proposal of a novel UAS platform, referred to as the ``Polycopter" for its morphing nature. This dual-tilt axis system has unique authority over is thrust vector, in addition to an ability to actively augment its stability and aerodynamic characteristics. This presents several opportunities in exploitative control design. With an approach to low-level UAS modelling and control proposed, the focus of the thesis shifts to investigate the challenges associated with local trajectory generation for the purpose of multi-agent collision avoidance. This begins with a novel survey of the state-of-the-art geometric approaches with respect to performance, scalability and tolerance to uncertainty. From this survey, the interval avoidance (IA) method is proposed, to incorporate trajectory uncertainty in the geometric derivation of escape trajectories. The method is shown to be more effective in ensuring safe separation in several of the presented conditions, however performance is shown to deteriorate in denser conflicts. Finally, it is shown how by re-framing the IA problem, three dimensional (3D) collision avoidance is achieved. The novel 3D IA method is shown to out perform the original method in three conflict cases by maintaining separation under the effects of uncertainty and in scenarios with multiple obstacles. The performance, scalability and uncertainty tolerance of each presented method is then examined in a set of scenarios resembling typical coordinated UAS operations in an exhaustive Monte-Carlo analysis

Orbit control for a spacecraft around a splitting contact binary asteroid

This thesis examines an orbit control problem for a spacecraft around a contact binary asteroid considering the dynamics of both the spacecraft and the asteroid itself. It is known that approximately 15\% of the near-Earth asteroids are binary, and among these the fraction of contact binaries is between 6 and 10%. Most contact binary asteroids are constituted of an agglomeration of smaller boulders maintained together due to their internal gravity, which is a relatively unstable configuration. Therefore, even a minor change in their mass distribution, like would be caused by the landing of mining machines, can result in a modification of the asteroid's structure including a landslide or a splitting. Particularly, separation of the asteroid into two parts is problematic in terms of orbit control, because of the consequences on the gravitational field of the asteroid. Traditional two-body orbital control methods cannot be applied to the missions to those asteroids because they do not consider the dynamic activities of the asteroids themselves. This thesis proposes and evaluates a control method to follow a predefined path under unknown states of the splitting binary asteroid

Optimal Planning and Guidance Strategies in Coplanar Circular Interplanetary Missions using Electric Solar Wind Sails

Las Velas Solares Eléctricas son un nuevo tipo de propulsión espacial que no requiere de combustible ya que obtiene la energía de los protones del viento solar, y que es potencialmente útil para misiones interplanetarias. Con un modelo propulsivo apropiado, que puede ser obtenido de la literatura, es posible estudiar órbitas óptimas para vuelos interplanetarios. El primer objetivo de este proyecto es estudiar las propiedades de las órbitas de tiempo mínimo en misiones hacia Marte y Júpiter utilizando un método indirecto aplicando las ecuaciones de Euler-Lagrange y el Principio del Mínimo de Pontryagin, y luego hallar dichas órbitas usando métodos de transcripción directa para convertir el problema en un problema de Programación No Lineal. Tras esto, se añaden las perturbaciones del viento solar, y múltiples estrategias de guiado basadas en el Regulador Cuadrático Lineal y el Control Predictivo por Modelo se desarrollan, simulan y comparan, obteniendo resultados satisfactorios.Electric Solar Wind Sails are a new type of spacecraft propellantless propulsion system that gathers its energy from solar wind protons and is potentially useful for interplanetary missions. With an appropriate thrust model, which can be obtained from the literature, one can study optimal orbits for interplanetary flights. The first goal of this project is to study the properties of time-optimal orbits for missions to Mars and Jupiter using an indirect approach by applying Euler-Lagrange equations and Pontryagin’s Minimum Principle, and then compute them with direct transcription methods, converting the problem into Non Linear Programming form. Then, solar wind perturbations are added, and several guidance strategies based on Linear Quadratic Regulator Control and Model Predictive Control are developed, simulated and compared, yielding satisfactory results.Universidad de Sevilla. Grado en Ingeniería Aeroespacial

1992 NASA/ASEE Summer Faculty Fellowship Program

For the 28th consecutive year, a NASA/ASEE Summer Faculty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The program was conducted by the University of Alabama and MSFC during the period June 1, 1992 through August 7, 1992. Operated under the auspices of the American Society for Engineering Education, the MSFC program, was well as those at other centers, was sponsored by the Office of Educational Affairs, NASA Headquarters, Washington, DC. The basic objectives of the programs, which are the 29th year of operation nationally, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate and exchange ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA centers