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Full-Text Articles in Space Vehicles
Military Space Mission Design And Analysis In A Multi-Body Environment: An Investigation Of High-Altitude Orbits As Alternative Transfer Paths, Parking Orbits For Reconstitution, And Unconventional Mission Orbits, John N. Brick
Theses and Dissertations
High-altitude satellite trajectories are analyzed in the Earth-Moon circular restricted three-body problem. The equations of motion for this dynamical model possess no known closed-form analytical solution; therefore, numerical methods are employed. To gain insight into the dynamics of high-altitude trajectories in this multi-body dynamical environment, periapsis Poincare' maps are generated at particular values of the Jacobi Constant. These maps are employed as visual aids to generate initial guesses for orbital transfers and to determine the predictability of the long term behavior of a spacecraft's trajectory. Results of the current investigation demonstrate that high-altitude transfers may be performed for comparable, and …
Minimum-Fuel Trajectory Design In Multiple Dynamical Environments Utilizing Direct Transcription Methods And Particle Swarm Optimization, Alfredo G. Zurita Jr.
Minimum-Fuel Trajectory Design In Multiple Dynamical Environments Utilizing Direct Transcription Methods And Particle Swarm Optimization, Alfredo G. Zurita Jr.
Theses and Dissertations
Particle swarm optimization is used to generate an initial guess for designing fuel-optimal trajectories in multiple dynamical environments. Trajectories designed in the vicinity of Earth use continuous or finite low-thrust burning and transfer from an inclined or equatorial circular low-Earth-orbit to a geostationary orbit. In addition, a trajectory from near-Earth to a periodic orbit about the cislunar Lagrange point with minimized impulsive burn costs is designed within a multi-body dynamical environment. Direct transcription is used in conjunction with a nonlinear optimizer to find locally-optimal trajectories given the initial guess. The near-Earth transfers are propagated at low-level thrust where neither the …
Military Applications Of High-Altitude Satellite Orbits In A Multi-Body Dynamical Environment Using Numerical Methods And Dynamical Systems Theory, Meredith M. Wilmer
Military Applications Of High-Altitude Satellite Orbits In A Multi-Body Dynamical Environment Using Numerical Methods And Dynamical Systems Theory, Meredith M. Wilmer
Theses and Dissertations
The circular restricted three-body problem (CR3BP) is a simplified dynamical model for a satellite under the gravitational influence of both the Earth and the Moon, maintaining closer fidelity to the gravitational environment experienced by a high-altitude Earth-orbiting spacecraft than modeling in the Earth-satellite two-body problem. Resonant orbit arcs are used to determine an initial guess to input into an algorithm that computes a trajectory solution with specific design requirements and constraints. A test case uses this method to compute a lunar fly-by transfer solution requiring less than two-body transfer methods and offers an unusual pathway that adds an unpredictability element …
Multi-Cubesat Deployment Strategies: How Different Satellite Deployment Schemes Affect Satellite Separation And Detection For Various Types Of Constellations And Missions, Scott A. Biehl Jr.
Multi-Cubesat Deployment Strategies: How Different Satellite Deployment Schemes Affect Satellite Separation And Detection For Various Types Of Constellations And Missions, Scott A. Biehl Jr.
Theses and Dissertations
As economics drive an increased demand for small satellites and, consequently, an increase in the number of satellites deployed per launch, different deployment schemes and their effects on satellite dynamics must be well understood. While there are advantages to deploying multiple satellites at once, users may have trouble with tracking, identifying, and communicating with their satellites. This investigation examines the deployment of eight 3U CubeSats, and the resulting relative motion within a constellation. Both the distance between any two satellites within a constellation and the volume of a polygon encompassing a constellation are used to analyze the satellite dynamics within …
Space Object Self-Tracker On-Board Orbit Determination Analysis, Stacie M. Flamos
Space Object Self-Tracker On-Board Orbit Determination Analysis, Stacie M. Flamos
Theses and Dissertations
Due to the United States' growing dependence on space based assets and the in- creasing number of resident space objects (RSO), improvement of Space Situational Awareness (SSA) capabilities is more necessary than ever. As a way to aid in this need, the Air Force Institute of Technology (AFIT) is developing the Space Object Self-Tracker (SOS) as a proof-of-concept experimental satellite for RSO precision tracking and collision avoidance system in Low Earth Orbit (LEO). Specifically, SOS will use Global Positioning System (GPS) position estimates for on-board orbit de- termination. Currently, SOS will use the Simplified General Perturbations-4 (SGP4) algorithm as its …
Development Of A Modularized Software Architecture To Enhance Ssa With Cots Telescopes, Julian P. Mccafferty
Development Of A Modularized Software Architecture To Enhance Ssa With Cots Telescopes, Julian P. Mccafferty
Theses and Dissertations
As the catalog of Earth orbiting objects continues to grow exponentially, so too does the necessity for Space Situational Awareness (SSA). Previous work at AFIT has explored augmenting the Space Surveillance Network (SSN) by demonstrating detection and tracking of orbiting objects using Commercial-Off-The-Shelf (COTS) telescopes and Air Force generated Two-Line Element Sets (TLE). This research explores the process of developing and reengineering code into a modularized, hierarchical component architecture designed for the end user while enabling developers to continue to modify the software for future applications. Three graphical user interfaces (GUI) are compiled into standalone executable programs using MATLAB for …