Aerospace Engineering Commons^™

Interplanetary Gravity Assisted Trajectory Optimizer (Igato), Jason Bryan

Aerospace Engineering

Interplanetary space travel is an extremely complicated endeavor that is severely limited by our current technological advancements. The amount of energy required to transport a spacecraft from one planet to the next, or even further, is extraordinary and in some cases is even impossible given our current propulsive capabilities. Due to these complications, the search for other means of exchanging energy became imperative to future space exploration missions. One particularly powerful method that was discovered, and the most commonly used one, is referred to as planetary gravity assist. In order to plan out multiple gravity assist trajectories, complex and robust …

Senior Project: Global Position Determination From Observed Relative Position Of Celestial Bodies, Michael Holmes

Aerospace Engineering

A method was developed to determine the latitude and longitude of an observer based on the observed position of the Moon and several other celestial bodies. The basic principal developed dealt with the proximity of the Moon. Its relative displacement from calculated values was measured using photography by comparison with stars near the Moon. Photographs were taken from a location in San Luis Obispo at Longitude 120°35.9' and Latitude 35°13.3'. The analysis method has determined the location of the observer to a Longitude of 117°43.8'. An additional method located the observer to 36°38.7'N Latitude and 114°47.6'W Longitude.

Matlab® Gui Visualization Of Classical Orbital Elements, Nancy Teresa Cabrera

Aerospace Engineering

The classical orbital elements of an orbit are eccentricity, angular momentum, inclination, right ascension of ascending node, true anomaly, and argument of perigee. These six parameters define an orbit. Using MATLAB® to model a satellite orbiting Earth in three dimensions, a graphical user interface was created to allow a user to manipulate the orbital elements to desired quantities. In doing so, each parameter’s impact on the orbit is visually displayed. This furthers the understanding of how the parameters are linked to the orbit. When the interface is first opened, the default circular orbit has a range of 20,000 kilometers, an …

Design Analysis Of A Sapce Based Chromotomographic Hyperspectral Imaging Experiment, Todd A. Book

Theses and Dissertations

This research develops the design of several components and/or systems for an experimental space-based chromotomographic hyperspectral imager that is being built by the Air Force Institute of Technology. The design work includes three separate topics. The first topic was the development of a structure utilizing finite element analysis and eigenanalysis for the ground-based version of the chromotomographic experiment (CTEx). The ground-based experiment was performed as a risk mitigation measure for the space-based experiment. The second topic includes a design review of a contractor's proposed off-axis Mersenne telescope for the space-based chromotomographic hyperspectral imager. The work included the creation of preliminary …

Relative Orbit Elements For Satellites In Elliptical Orbits, Kirk W. Johnson

Theses and Dissertations

The purpose of this research was to describe the unperturbed relative motion of Earth satellites in elliptical orbits using a simple dynamics model whose parameters allow significant geometrical insight and operational efficacy. The goal was to retain the advantages of the Relative Orbit Elements (ROE) realization of the Hill-Clohessy-Wiltshire (HCW) equations, a linearized dynamics model for circular reference orbits. Specifically, this thesis analyzed the geometry of satellite rendezvous and proximity operations using the ROE parameters to characterize the model’s utility. Next, through a comprehensive literature review, this thesis sought possible approaches for developing a similarly useful parameterization for chief orbits …

Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller

Theses and Dissertations

This research effort develops an interdisciplinary design tool to optimize an orbit for the purpose of wirelessly beaming power from the International Space Stations (ISS) Japanese Experimental Module Exposed Facility (JEM/EF) to a target satellite. For the purpose of this initiative, the target satellite will be referred to as FalconSAT6, a reference to the proposed follow-on satellite to the U.S. Air Force Academy’s (USAFA) FalconSAT5 program. The USAFA FalconSAT program provides cadets an opportunity to design, analyze, build, test and operate small satellites to conduct Department of Defense (DoD) space missions. The tool developed for this research is designed to …

Accurate Dynamic Response Predictions Of Pnpsat I, Michael D. Trottier

Theses and Dissertations

Researchers at the Air Force Institute of Technology (AFIT) and the Operationally Responsive Space (ORS) Office have conducted extensive vibration testing and structural modeling on the first ORS Plug-and-Play Satellite (PnPSAT I). The intent of this research effort is to evaluate the premise that current post-integration spacecraft environmental test requirements can be reduced or modified using accurately tuned finite element (FE) models. As part of this research, modal testing was conducted on the PnPSAT I structural panels at AFIT. The modal testing was part of a much larger series of experimental trials on various configurations of PnPSAT I at the …

Mission Analysis For Multiple Rendezvous Of Near-Earth Asteroids Using Earth Gravity Assist, Uriah J. Tobey

Theses and Dissertations

The Jet Propulsion Laboratory (JPL) catalog of near-Earth objects (NEOs) such as asteroids and comets contains over 6600 asteroids and 150 comets as of February of 2010. This includes over 1000 potentially hazardous asteroids, or objects with orbits that pass close enough to Earth to pose a potential impact threat. The asteroid community believes there are a significant number of objects still undiscovered, which makes finding, tracking, and calculating missions to study these objects an active area of research. This study was based on finding orbit solutions using Earth gravity assist to visit one near-Earth object (NEO) a year for …

Attitude Control Of A Satellite Simulator Using Reaction Wheels And A Pid Controller, Ryan E. Snider

Theses and Dissertations

Attitude requirements of a satellite are determined by its mission: telecommunications, optical imagery, and meteorology to name a few. A satellite's ability to orient its mission critical hardware (solar arrays, attitude sensors, etc.), as well as its mission specific payload, is incumbent upon the performance of the satellite's attitude control system (ACS). For a highly accurate ACS and for moderately fast maneuverability, reaction wheels are preferred because they allow continuous and smooth control while inducing the smallest possible disturbance torques. The objective of this research is to design, build, test, and evaluate the performance of a reaction wheel ACS on-board …

Prototype Development And Dynamic Characterization Of Deployable Cubesat Booms, Grant M. Thomas

Theses and Dissertations

The current barrier to CubeSat proliferation is their lack of utility depth. These small satellites are exceptionally well suited for specific space missions such as space weather observation and other scientific data gathering exploits; however, they are not suited for every mission. The 10cm-cube form factor that gives the CubeSat its unique advantage is also its greatest hindrance. A potential bridge over this gap is the successful integration of deployable booms onto the CubeSat structure. With this research, the Air Force Institute of Technology (AFIT) explored the parameters of deployable tapespring booms using the triangular retractable and collapsible (TRAC) cross- …

Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse

Theses and Dissertations

This thesis outlines the design of the electrical components for the space-based ChromoTomography Experiment (CTEx). CTEx is the next step in the development of high-speed chromotomography at the Air Force Institute of Technology. The electrical design of the system is challenging due to the large amount of data that is acquired by the imager and the limited resources that is inherent with space-based systems. Additional complication to the design is the need to know the angle of a spinning prism that is in the field of view very precisely for each image. Without this precise measurement any scene that is …

System Integration And Attitude Control Of A Low-Cost Spacecraft Attitude Dynamics Simulator, Ryan L. Kinnett

Master's Theses

The CalPoly Spacecraft Attitude Dynamics Simulator mimics the rotational dynamics of a spacecraft in orbit and acts as a testbed for spacecraft attitude control system development and demonstration. Prior to this thesis, the simulator platform and several subsystems had been designed and manufactured, but the total simulator system was not yet capable of closed-loop attitude control. Previous attempts to make the system controllable were primarily mired by data transport performance. Rather than exporting data to an external command computer, the strategy implemented in this thesis relies on a compact computer onboard the simulator platform to handle both attitude control processing …

Adaptive Control Applied To The Cal Poly Spacecraft Attitude Dynamics Simulator, Matthew C. Downs

Master's Theses

The goal of this thesis is to use the Cal Poly Spacecraft Attitude Dynamics Simulator to provide proof of concept of two adaptive control theories developed by former Cal Poly students: Nonlinear Direct Model Reference Adaptive Control and Adaptive Output Feedback Control. The Spacecraft Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft scenario, and under simulated actuator damage. Proof of concept of the adaptive control theories applied to attitude …

Orbital Propagators For Horizon Simulation Framework, Mitra Farahmand

Master's Theses

This thesis describes the models of four common orbital propagators and outlines the process of integrating them into the Horizon Simulation Framework (HSF). The results of the Two-Body, J2, and J4 propagators from the HSF are then compared against the outcomes of these propagators in MATLAB and Satellite Toolkit (STK). The MATLAB algorithms verify the functionality of the propagators and determine the accuracy of the HSF implementation. The compassion against STK validates the formulation of the HSF propagators. In order to equip the HSF with a more precise means of orbit determination, adding the Simplified General Perturbations 4 (SGP4) propagator …

Formation Flight Of Earth Satellites On Kam Tori, Christopher T. Craft

Theses and Dissertations

Kolmogorov, Arnold and Moser (KAM) theory provides that orbits of satellites whose dynamics are representable by an integrable Hamiltonian plus a small, real perturbation lie on tori in phase space and remain on the KAM tori for all time, unless acted upon by a non-conservative force. A refined technique for constructing KAM tori for Earth-orbiting satellites is developed and implemented using numerically integrated orbital data for hypothetical satellites and involving methods of Fourier analysis and spectral decomposition. Definition of satellite formations on the KAM tori is performed and analyses conducted to investigate both constellations with large separations and clusters with …

Comparison And Design Of Simplified General Perturbation Models (Sgp4) And Code For Nasa Johnson Space Center, Orbital Debris Program Office, Nicholas Z. Miura

Master's Theses

This graduate project compares legacy simplified general perturbation model (SGP4) code developed by NASA Johnson Space Center, Orbital Debris Program Office, to a recent public release of SGP4 code by David Vallado. The legacy code is a subroutine in a larger program named PREDICT, which is used to predict the location of orbital debris in GEO. Direct comparison of the codes showed that the new code yields better results for GEO objects, which are more accurate by orders of magnitude (error in meters rather than kilometers). The public release of SGP4 also provides effective results for LEO and MEO objects …

Satellite Reentry Control Via Surface Area Amplification, Salvador Alemán

Theses and Dissertations

This project endeavors to find whether it is feasible to use an increase in surface area as a way of increasing the drag on an orbiting object, thus decreasing its orbital lifetime. The surface area increase can be achieved by an apparatus that deploys a balloon. The balloon will act as a parachute that will decrease the potential energy of the object through atmospheric drag. This is most effective by objects that reach the Low Earth altitudes of less than 500 kilometers, where an object is encountering a firmer atmospheric density. The project is carried out through propagating three different …

Application Of Kam Theorem To Earth Orbiting Satellites, Bryan D. Little

Theses and Dissertations

An orbit that lies on a Kolmogorov, Arnold, and Moser (KAM) Torus will remain on that torus until and unless it experiences a force that causes it to leave the torus. Earth satellites that are subject only to the Earth's gravity field may lie on such KAM tori. Analyzing on orbit satellite position data should allow for the identification of the fundamental frequencies needed to define the KAM tori for modeling Earth satellite orbits. KAM Tori are created for the Gravity Recovery and Climate Experience (GRACE) and Jason-1 satellites to model their orbital motion. Precise position data for the satellites …

Mission Planning For Close-Proximity Satellites, Barry R. Witt

Theses and Dissertations

Given an initial orbit and a set of other orbits of interest, the lowest change in velocity "path" between them is of high value. Software was developed to visualize the change in velocity required from a user defined window of burn to a user defined window of intercept. The time between burn and intercept is unrestricted. Multiple intercepts require searching an n! solution space, research then is focused on ways to pick optimal choices without fully calculating out the cost of doing all possible combinations. Some code was translated from BASIC and the rest was newly developed in MATLAB. The …

Development, Verification, And Future Applications Of A 3-Dof Entry And Descent Simulation Tool, Shaun Deacon

Master's Theses - Daytona Beach

With any space related mission, the unknown effects are often some of the most important design considerations. These effects must be accounted for in some fashion, and often lead to mission elements being centered around gathering information on the unknown.

It is the purpose of this research to develop and test a tool for simulation of entry, descent, and landing, (EDL) and to present a brief analysis of possible dispersion patterns related to autonomous radiosonde deployment on the surface of Mars.

The EDL simulation tool is written in Matlab. The aerodynamic information used by the tool is obtained with the …

Modeling Gps Satellite Orbits Using Kam Tori, Rachel M. Derbis

Theses and Dissertations

Global Positioning System (GPS) satellite orbits are modeled using Kolmogorov, Arnold, Moser (KAM) tori. Precise Global Positioning System satellite locations are analyzed using Fourier transforms to identify the three basis frequencies in an Earth Centered, Earth Fixed (ECEF) rotating reference frame. The three fundamental frequencies are 1) the anomalistic frequency, 2) a combination of earth’s rotational frequency and the nodal regression rate, and 3) the apsidial regression rate. A KAM tori model fit to the satellite data could be used to predict future satellite locations. This model would allow rapid determination with fewer computational requirements than the typical method of …

Minimizing Secular J2 Perturbation Effects On Satellite Formations, Jonathan W. Wright

Theses and Dissertations

The purpose of this thesis is to examine the secular effects of the J₂ oblateness perturbation on close proximity satellites. The main objective is to analyze the deputy’s position and velocity with respect to the chief and adjust the initial conditions of the deputy in an attempt to minimize the secular effects of J₂ perturbations. Previous work has provided a method of obtaining a closed form solution for J₂ invariance with co-planar orbits. Therefore, this work will primarily consider deputy orbits that experience motion outside of the chief’s orbital plane. Upon determining the required initial conditions, the …

Crew Exploration Vehicle (Cev) Skip Entry Trajectory, Emre Kaya

Theses and Dissertations

This research effort develops a program using MATLAB® to solve the equations of motion for the atmospheric reentry of the Crew Exploration Vehicle (CEV) which is assumed to be in the phase of a lunar return trajectory that could be initiated any time during the mission. The essential reason for this research is to find a solution for the problem of an unplanned lunar return in addition to the normal procedures. Unlike Apollo type missions, the CEV would still be able to land on any preplanned available landing sites without any additional delay. In Apollo type missions, the return phase …

Initial Determination Of Low Earth Orbits Using Commercial Telescopes, Matthew M. Schmunk

Theses and Dissertations

Within the last decade, many new technologies have significantly changed the face of private astronomy. Developments such as inexpensive but high-quality sensors, rapid personal computing, and easy networking inspire a reexamination of an old problem: how practical is it to develop initial orbit estimates for Low Earth Orbiting (LEO) satellites using optical tracking? This paper documents the design and implementation of a commercial telescope system used to answer precisely that question. This analysis deter- mined there are some challenging barriers to successful single-site orbit determination, but it is possible given the right conditions. Considering the low cost and small sup- …

Attitude Determination Using Imaging Lidar, Camille Decoust

Master's Theses - Daytona Beach

The purpose of this study is to determine the attitude of an out of control object using a new technology called lidar (Light Ranging and Detection). As the number of spacecraft continues to grow, it is paramount to introduce a new type of autonomous on-orbit satellite inspection and repair involving docking. Traditional space vision technology is based on video systems. This method is limited by the necessity of operating when the target is illuminated by the sunlight or using its own source of illumination. The use of laser imaging technology offers an elegant solution to these challenges. This approach allows …

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly

Renée Crown University Honors Thesis Projects - All

Using experimental methods, zero net-mass flow actuators were optimized to manipulate flow around an airborne laser turret in order to reduce destructive aero-optics effects. Synthetic jets are created by 50 mm and 27 mm piezoelectric disk actuators. Our optimization process involved identifying an actuator’s cavity size, driving frequency, and amplitude to achieve the strongest, most consistent jet possible. The effects of driving a single actuator versus driving two actuators in or out of phase with one another were also investigated. An initial cavity depth was determined using the Helmholtz resonator cavity approximation which estimates the ideal cavity depth for a …

Optimization Of Zero Net-Mass Flow Actuators For Aero-Optics Applications, Moira L. Denatale, Jonathan M. Mihaly

Renée Crown University Honors Thesis Projects - All

Using experimental methods, zero net-mass flow actuators were optimized to manipulate flow around an airborne laser turret in order to reduce destructive aero-optics effects. Synthetic jets are created by 50 mm and 27 mm piezoelectric disk actuators. Our optimization process involved identifying an actuator’s cavity size, driving frequency, and amplitude to achieve the strongest, most consistent jet possible. The effects of driving a single actuator versus driving two actuators in or out of phase with one another were also investigated. An initial cavity depth was determined using the Helmholtz resonator cavity approximation which estimates the ideal cavity depth for a …

Satellite Attitude Control Using Atmopheric Drag, David B. Guettler

Theses and Dissertations

Attitude control is a requirement for most satellites. Many schemes have been devised over the years including control moment gyros, reaction wheels, spin stabilization and gravity gradient stabilization. For low Earth orbits, the Earth's atmosphere can have an affect on a satellite's orbit and attitude. This research effort examines the feasibility of using the atmosphere to actively control a spacecraft's attitude using drag panels. Using the atmosphere to control spacecraft attitude has been researched in the past however very little research has been done using an active feedback control system to maintain spacecraft attitude. A linear computer model was created …

Spacecraft Proximity Operations Used To Estimate The Dynamical & Physical Properties Of A Resident Space Object, Abraham F. Brunner

Theses and Dissertations

When conducting a space proximity operation, developing high-fidelity estimates of the dynamical and physical properties of a Resident Space Object (RSO) based on post-rendezvous observational data acquired, is imperative for the understanding of the RSO itself and the operating environment. This research investigates the estimation of relative motion dynamics, rotational dynamics, and the feasibility of estimating the moments of inertia of a RSO. Using the Hill-Clohessy-Wiltshire equations, rigid-body dynamics, and estimation theory, a nonlinear least squares estimation algorithm is implemented in the processing of range data from tracked observation points on the RSO body. Through simulation, it was determined that …

Optimal Orbital Coverage Of Theater Operations And Targets, Kimberly A. Sugrue

Theses and Dissertations

The use of satellites as a tactical asset to support theater operations is a desired capability for future space operations. Unlike traditional satellite systems designed to provide coverage over the entire globe or large regions, tactical satellites would provide coverage over a small region which can be modeled as a single ground point defined by a latitude and longitude. In order to provide sufficient utility as a theater asset, a satellite should be placed in an orbit that provides a maximum amount of coverage of the target ground point. This study examined the optimization of orbit parameters to maximize the …