MS, University of Cincinnati, 2016, Engineering and Applied Science: Aerospace Engineering

This thesis concentrates on developing an innovative method to generate thrust force for spacecraft in localized geomagnetic fields by various electromagnetic systems. The proposed electromagnetic propulsion system is an electromagnet, like normal or superconducting solenoid, having its own magnetic field which interacts with the planet's magnetic field to produce a reaction thrust force. The practicality of the system is checked by performing simulations in order the find the varying radius, velocity, and acceleration changes. The advantages, challenges, various optimization techniques, and viability of such a propulsion system in present day and future are discussed. The propulsion system such developed is comparable to modern MPD Thrusters and electric engines, and has various applications like spacecraft propulsion, orbit transfer and stationkeeping.

Committee: Grant Schaffner Ph.D. (Committee Chair); George T Black M.S. (Committee Member); Kelly Cohen Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science, The Ohio State University, 2011, Aero/Astro Engineering

Spacecraft trajectory design is a science that requires high precision with little error. One of the most classic trajectory design problems is the restricted three-body problem. Two methods to develop the trajectory of a spacecraft under the influence of two celestial bodies are through the use of the equations of motion, and the patched-conic approximation. Popular tools such as MATLAB can be used to solve the equations of motion if great care is taken when selecting an ODE solver since the results are dramatically different between different solvers. As a result, these tools aren't very robust and can create significant errors, so a different approach must be used for generalized scenarios when an exact solution for comparison is unavailable. The patched-conic approximation can be easily used in a program such as MATLAB, but its exclusion of one of the two celestial bodies at every point in the trajectory creates drawbacks and significant errors. To avoid the errors that exist when using the patched-conic approach, research was put into the development of a simple model that could propagate a spacecraft's trajectory under the effect of two celestial bodies while being robust enough to code and solve in a widely available program such as MATLAB. This model acts as a modification to the patched-conic approach. Throughout the trajectory the effect of the primary celestial body of the system on the spacecraft was calculated, as in the patched-conic approach, however unlike the patched-conic approach this effect is not ignored when the spacecraft reaches the secondary body's sphere of influence. Furthermore, the effect of the secondary body was also considered even when the spacecraft is outside the secondary body's sphere of influence. Then, by applying a weighted average to the spacecraft's radius and velocity components respective to each celestial body, an updated state would be created that would allow the model to accurately propagate the trajectory. This woul (open full item for complete abstract)

Committee: Hayrani Oz Dr. (Advisor); Rama Yedavalli Dr. (Committee Member) Subjects: Aerospace Engineering; Engineering

Master of Science in Engineering, University of Akron, 2025, Mechanical Engineering

Spacecraft inspection plays a critical role in ensuring the safety and longevity of missions, particularly during extended space missions where maintenance and repairs are limited. A successful spacecraft inspection must be able to accurately assess the condition of a spacecraft, focusing on the surface or subsurface assessments. The pur-poses for a spacecraft inspection include recognizing specific damage patterns and diag-nosing faults, locating areas in need of upgrades, keeping compliance with safety codes, environmental data collection, and more. Traditional inspection techniques are often labor-intensive, time-consuming, and reliant on ground-based facilities. This study explores the feasibility of using 3D scanning technology for inspect-ing spacecraft hulls while on-orbit. By testing both laser and light-based scanners under simulated space conditions, including shadowed and sunny sides, this study investi-gates the ability to capture accurate, high-resolution data for detecting structural damage. The results indicate that 3D scanning can be an effective method for on-orbit inspec-tions, with promising accuracy in fault detection across various spacecraft surfaces. These findings offer insights into the potential integration of scanning technology for autonomous spacecraft maintenance in space missions. The methodology consists of capturing detailed 3D scan data from spacecraft surfaces using a 3D scanner and transferring this data to fault detection software. The software analyzes the scans by comparing them to baseline models to identify any sur-face deformations, cracks, or other potential damage. Key parameters such as scanning accuracy, fault detection efficiency, and the impact of environmental conditions were considered throughout the study. The results indicate that lighting conditions significantly impact the accuracy of the structured light scanner, with performance deteriorating in direct light and low-light conditions. In contrast, the laser (open full item for complete abstract)

Committee: Siamak Farhad (Advisor); Xiaosheng Gao (Committee Member); Ajay Mahajan (Advisor) Subjects: Mechanical Engineering

Master of Engineering, Case Western Reserve University, 2025, EMC - Aerospace Engineering

Analysis of three missions has been carried out with a set of three power and three propulsion systems to determine system synergy as well as to find an optimal system for each mission. The three missions are GTO to LLO, LMO, and Titan flyby. The three propulsion systems of analysis are Hall Effect Thrusters, Magnetoplasmadynamic Thrusters, and VASIMR Thrusters. The three power systems of analysis are Silicon photovoltaics, multi-junction photovoltaics, and nuclear reactors. The mission to Low Lunar Orbit has a maximum trip time of 8 weeks, and four systems are capable of achieving this result. Those systems are Hall-Nuclear, MPDNuclear, VASIMR-MJ, and VASIMR-Nuclear, the last of which achieves the target in just 26 days. The VASIMR-Nuclear system is also capable of bringing the most passengers with a total capacity of 255 people. The mission to LMO was limited to a maximum trip time of 9 months, and 1 system is capable of achieving this result. This system is again VASIMR-Nuclear, capable of bringing 31 people the LMO in 241 days, or about 8 months. The mission to Titan flyby using the VASIMR-Nuclear system is capable of bringing 54500 kg of dry mass to Titan flyby at 1000 km at 3.13 km/s relative to the planet.

Committee: Paul Barnhart (Advisor); Majid Rashidi (Committee Member); Richard Bachmann (Committee Member) Subjects: Aerospace Engineering

Doctor of Philosophy, The Ohio State University, 2024, Environmental Science

Every occupied indoor environment, including spacecraft, has its own unique microbiome. This composition and quantity of the microbiome present in these environments is dependent on many factors including building materials, occupants cleaning habits, presence of pets, and environmental conditions inside. Indoor microbes can be found in dust, which is generated in both Earth- and space-based built environments, a unique nutrient rich substrate that can act as both a source and sink especially in Earth-based buildings with carpet. Unintended microbial growth indoors can affect the health of the occupants and cause premature failure of building materials via biodegradation. Water is the limiting factor for growth, with moisture in the indoor air sufficient to support microbial growth indoors, especially for fungi. However, we need an improved understanding of microbes and their growth in indoor spaces to ensure healthier environments. The goal of this paper is to provide these examples and show how they fit into the concepts of One Space and bioastronautics. One Space is the idea that the built environment and human health are interconnected based on the One Health principles. Bioastronautics is the study of living organisms in spaceflight conditions. These two ideas complement each other and provide ample opportunity for interdisciplinary collaborations that can lead to innovative solutions to making healthier, safer, and more comfortable built environments on Earth and in space. In these studies, we focus on the intersection between microbiology and the built environment, by looking at the indoor dust microbiome in Earth- and space-based built environments like the International Space Station (ISS). We show that bacteriophages in common Earth-based building materials such as carpet and house dust can remain viable and infectious for up to several days making it a potential source of exposure. We also found the viral genetic material (RNA) remained stable for weeks t (open full item for complete abstract)

Committee: Karen Dannemiller (Advisor); John Horack (Committee Member); Michael Bisesi (Committee Member); Natalie Hull (Committee Member) Subjects: Environmental Health; Environmental Science; Microbiology

Master of Sciences (Engineering), Case Western Reserve University, 2024, EMC - Aerospace Engineering

As deep space missions expand in scope and distance, the efficiency of propulsion systems becomes paramount. This thesis analyzes the impact of small measurement errors in the thrust profiles of Hall-Effect Thrusters, a common type of electric propulsor, known for increased efficiency compared to traditional chemical propulsion despite lower thrust. Due to their prolonged operational times, these errors compound, affecting trajectory and mission success. Through analyzing the AEPS Hall-Effect Thruster prototype, designed for NASA's Artemis Program's Gateway space station, using curve fitting and a Monte Carlo simulation, we assess the effects of these errors on an example mission to Alpha Centauri. Results show plasma dynamics cause the majority of error, but cause minimal trajectory deviation and propellant loss. This reinforces electric propulsion's suitability for long-distance space travel. This work informs spacecraft mission design, providing valuable insights into fuel efficiency and system selection, as well as building upon NASA Glenn Research Center's Electric Propulsion and Power Laboratory's prior research.

Committee: Bryan Schmidt (Committee Chair); John Yim (Other); Richard Bachmann (Committee Member); Paul Barnhart (Committee Member) Subjects: Aerospace Engineering; Engineering; Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2024, Aerospace Engineering

This research introduces an Origami-inspired dynamic spacecraft radiator, capable of adjusting heat rejection in response to orbital variations and extreme temperature fluctuations in lunar environments. The research centers around the square twist origami tessellation, an adaptable geometric structure with significant potential for revolutionizing radiative heat control in space. The investigative involves simulations of square twist origami tessellation panels using vector math and algebra. This study examines both a two-dimensional (2- D), infinitely thin tessellation, and a three-dimensional (3-D), rigidly-foldable tessellation, each characterized by an adjustable closure or actuation angle “φ”. Meticulously analyzed the heat loss characteristics of both the 2D and 3D radiators over a 180-degree range of actuation. Utilizing Monte Carlo Ray Tracing and the concept of “view factors”, the study quantifies radiative heat loss, exploring the interplay of emitted, interrupted, and escaped rays as the geometry adapts to various positions. This method allowed for an in-depth understanding of the changing radiative heat loss behavior as the tessellation actuates from fully closed to fully deployed. The findings reveal a significant divergence between the 2D and 3D square twist origami radiators. With an emissivity of 1, the 3D model demonstrated a slower decrease in the ratio of escaped to emitted rays (Ψ) as the closure/actuation angle increased, while the 2D model exhibited a more linear decline. This divergence underscores the superior radiative heat loss control capabilities of the 2D square twist origami geometry, offering a promising turndown ratio of 4.42, validating the model's efficiency and practicality for radiative heat loss control. Further exploration involved both non-rigidly and rigidly foldable radiator models. The non-rigidly foldable geometry, initially a theoretical concept, is realized through 3D modeling and physica (open full item for complete abstract)

Committee: Rydge Mulford (Advisor) Subjects: Acoustics; Aerospace Engineering; Aerospace Materials; Alternative Energy; Aquatic Sciences; Artificial Intelligence; Astronomy; Astrophysics; Atmosphere; Atmospheric Sciences; Automotive Engineering; Automotive Materials; Biomechanics; Biophysics; Cinematography; Civil Engineering; Communication; Computer Engineering; Design; Earth; Educational Software; Educational Technology; Educational Tests and Measurements; Educational Theory; Electrical Engineering; Engineering; Environmental Engineering; Environmental Science; Experiments; Fluid Dynamics; Geophysics; Geotechnology; High Temperature Physics; Industrial Engineering; Information Systems; Information Technology; Instructional Design; Marine Geology; Materials Science; Mathematics; Mathematics Education; Mechanical Engineering; Mechanics; Mineralogy; Mining Engineering; Naval Engineering; Nuclear Engineering; Nuclear Physics; Ocean Engineering; Petroleum Engineering; Quantum Physics; Radiation; Radiology; Range Management; Remote Sensing; Robotics; Solid State Physics; Sustainability; Systems Design; Theoretical Physics

PhD, University of Cincinnati, 2023, Engineering and Applied Science: Aerospace Engineering

Conventional control approaches have been developed based on mathematical models of systems that contain multiple user-defined parameters, and it is time-consuming to determine such parameters. With advancements in computing power, artificial intelligence (AI) has been recently used to control autonomous systems. However, it is difficult for engineers to understand how the resulting output is obtained because most AI techniques are a black box without defining a mathematical model. On the other hand, a fuzzy inference system (FIS) is a preferable option because of its explainability. By adding learning capability to the FIS using a genetic algorithm (GA), the FIS can provide a near-optimal solution, which is known as a genetic fuzzy system (GFS). To exploit the advantages of the GFS, this work develops the FIS-based control approaches for diverse autonomous platforms, which include aerial, ground, and space platforms. For aerial platforms, this work develops a FIS-applied collision avoidance (CA) algorithm that can provide a near-optimal solution in terms of the travel distance of unmanned aerial vehicles (UAVs). After introducing a compact form of equations, which reduces the number of unknown parameters from 6 to 2, based on the enhanced potential field (EPF) approach, the proposed FIS models determine two unknowns, which are the magnitude of the avoidance maneuvers. The proposed models are trained to overcome the drawbacks of the artificial potential field (APF) while minimizing the travel distance of the UAVs, the trained FIS models are tested in a complex environment in the presence of multiple static and dynamic obstacles by increasing the number of UAVs in a given area. Numerical simulation results are presented for the training and testing results, including the comparison with the EPF. For ground platforms, this work proposes a decentralized multi-robot system (MRS) control approach to perform a collaborative object transportation with a near- (open full item for complete abstract)

Committee: Donghoon Kim Ph.D. (Committee Chair); Anoop Sathyan Ph.D. (Committee Member); Ou Ma Ph.D. (Committee Member); Kelly Cohen Ph.D. (Committee Member) Subjects: Aerospace Engineering

Master of Science (M.S.), University of Dayton, 2021, Mechanical Engineering

Radiative fin technology is used in a wide variety of applications: automotive, electronics, and space. However, throughout history, radiative fin geometry is generally only analyzed along the thickness profile. This work analyzes radiative fin planar geometry and thickness profile in tandem. From there, the findings are used to investigate a novel dynamic spacecraft radiator system. Fins are analyzed to optimize for a variety of performance criteria, including maximum heat transfer, tip temperature, or fin efficiency. For analysis of both static and dynamic fins, a two-dimensional mathematical heat transfer model is developed. It is found that a triangular thickness profile is most critical for heat rate maximization. A fin with a triangular thickness profile increases heat rate by 38.8% when compared to a fin with identical planar geometry and volume, but with a uniform thickness profile. Planar shape is also found to influence fin performance. A fin with a rectangular planar geometry has a 6.8% increase in heat transfer as compared to a fin with a triangular planar geometry and identical thickness profile and volume. Additionally, it is also found that triangular thickness profiles produce the maximally efficient fins. Following these results, a novel design for a dynamic spacecraft radiator with annular geometry and varied thickness profiles is presented. It is found that turndown ratios of 3.33 are capable with the novel system. Furthermore, it was found that fins with tapered thickness profile have the highest efficiency and turndown ratio. Finally, it was shown that turndown ratio and fin efficiency decrease as operating temperature increases.

Committee: Rydge Mulford (Committee Chair); Andrew Schrader (Committee Member); Kevin Hallinan (Committee Member); Andrew Chiasson (Committee Member) Subjects: Aerospace Engineering; Applied Mathematics; Engineering; Mechanical Engineering; Radiation

Master of Science, The Ohio State University, 2021, Aerospace Engineering

The placement of cryogenic fuel/propellant depot stations in Earth orbit has the potential to transform the nature and operations for many types of spaceflight missions. Today, spaceflight missions are almost universally required to carry the entire amount of fuel required for the mission, for the entire duration of the mission, from the point of launch. This is the rough equivalent of making a drive from Ohio to California, requiring the traveler to bring along the total sum of gasoline required for the entire trip, without being able to `fill-up' anywhere along the route. Obviously, this framework of travel greatly encumbers the breadth, scope, and efficiency of potential journeys. Cryogenic fuel/propellant depots have not been implemented because many technical, operational, and engineering challenges still exist. These must be overcome prior to the placement of usable on-orbit propellant depots. This thesis investigates three specific engineering challenges related to on-orbit propellant depots, and presents the current state, technological challenges, and ultimate benefits of on-orbit cryogenic refueling. This thesis begins with a literature review of past and present research endeavors being undertaken to realize on-orbit refueling depots, focusing on the technologies necessary for and the orbital mechanics associated with cryogenic fuel depot operations. Then, an orbital dynamics study is conducted, and a method for computing refueling orbits to optimize total mission architecture mass savings over a no-refueling, single rocket case is presented. A MATLAB script has been written that allows for calculation and assessment of optimal refueling orbits around the Earth and Moon for deep space missions, utilizing specific impulses of engines and mass ratios of stages as inputs. Python is also used in conjunction with this MATLAB script to compute launch windows and to create dedicated plots to find optimal mission windows for minimizing mission energy requireme (open full item for complete abstract)

Committee: John Horack (Advisor) Subjects: Aerospace Engineering; Astrophysics; Engineering

Doctor of Philosophy, Case Western Reserve University, 2021, EECS - Electrical Engineering

A combined high-frequency fault detection and control framework for an autonomous DC microgrid is developed in this work. The dynamics and constraints of the power system are conveniently represented in a system which automatically produces gains that stabilize the system and minimize a performance functional that includes both state and actuator costs. This technique is applied to the low-frequency dynamics of the secondary controller and to the high-frequency dynamics of the DC-DC converters. The automatic gain scheduling is further investigated to determine its ability to support a system where there is insufficient frequency separation between the high-frequency (fast) and low-frequency (slow) subsystems. In addition to the controls work, high-frequency sampling of power system transients is studied for fault identification. Machine learning techniques are used to detect and identify abnormal operating conditions. Coordination between the fault detection and control systems is studied, and it is shown that the system is capable of responding to fault events and re-stabilize the system with new gains, both in the slow and fast subsystems. The system is also shown to be capable of detecting transients indicating deteriorating stability margins, and in this case new gains are automatically produced to restore the desired stability margins.

Committee: Kenneth Loparo (Advisor); Vira Chankong (Committee Member); Hanieh Agharazi (Committee Member); Robert Gao (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, Case Western Reserve University, 2021, EECS - System and Control Engineering

This dissertation formulates the problem of fault detection and diagnosis of DC electric power systems for the application of autonomous spacecraft. The ability to accurately identify and isolate failures in the electrical power system is critical to ensure the reliability of a spacecraft. This problem becomes more pronounced during deep space missions that lack the ability to monitor from ground control. The current state of electrical power system fault supervision is insufficient to guarantee highly reliable and robust operation. To solve this issue, a combination of model-based and rules-based techniques are used in a hierarchical framework to improve the diagnostic performance of the spacecraft electrical power system. Noise, disturbances, and modeling errors are considered in the design of the method. Practical considerations related to the hardware and software are discussed for the flight application. A wide array of failure types are simulated in a series of experiments to assess the functionality of the design. The experiments showed that the methods used improved the diagnostic capability of the autonomous system while taking into account the limitations attributed to flight software requirements. The significance of this study is to provide a framework capable of advanced diagnostics of an electrical power system with little to no interaction from a human operator.

Committee: Kenneth Loparo (Advisor); Vira Chankong (Committee Member); Kalmesh Mathur (Committee Member); Farhad Kaffashi (Committee Member) Subjects: Electrical Engineering; Energy

MS, University of Cincinnati, 2015, Engineering and Applied Science: Aerospace Engineering

The problem of landing a small spacecraft on the surface of an asteroid is analyzed in this thesis. The main effort of the thesis is focused around developing a fuzzy logic system to act as the controller. The fuzzy logic system is paired with a genetic algorithm to optimize the controller's membership functions. This optimized controller is then compared with two established controllers: an Optimal Control approach, and a Multiple Sliding-Surfaces Guidance algorithm. The genetic-fuzzy approach presented is applicable to designing controllers for various spacecraft and asteroid profiles.

Committee: Grant Schaffner Ph.D. (Committee Chair); Kelly Cohen Ph.D. (Committee Member); Elad Kivelevitch Ph.D. (Committee Member) Subjects: Aerospace Materials

MS, University of Cincinnati, 2007, Engineering : Aerospace Engineering

The novel concept of multiple spacecraft formation flying as a substitute for a single large vehicle will enhance future space mission performance. The benefits of a spacecraft formation include more cost effective synthetic aperture radar for observations, “graceful degradation” of the formation, flexibility of the satellites altering their roles, reduction of cost owing to the reduction of mass launched into orbit etc. A significant challenge in the domain of control design is to contrive a formation maintenance controller that will enable the member spacecrafts to maintain a desired relative orbit with minimal propellant expenditure. This thesis examines linear and nonlinear LEO formation control methodologies, one of each type, with the aim of evaluating them from a propellant budget, thrust level and error dynamics standpoint. A Linear Quadratic Regulator has been applied on J2-perturbed Clohessy-Wiltshire dynamics. In order to remove the restriction of the applicability of Cartesian local vertical local horrizontal frame based control laws to only circular leader orbits, a sliding mode controller acting on a full nonlinear dynamical model has been implemented.This work also studies the effects of leader orbit eccentricity, inclination and formation radius on formation keeping fuel demand and tracking error. Finally, conclusions are drawn regarding the suitability of the control laws considered and various recommendations made.

Committee: Dr. Albert Bosse (Advisor) Subjects: Engineering, Aerospace

Doctor of Philosophy, The Ohio State University, 2011, Aero/Astro Engineering

Recently, the idea of using Ecological Sign Stability approach for designing robust controllers for engineering systems has attracted attention with promising results. In this work, continued research on this topic is presented. It is well known that, in the field of control systems, key to a good controller design is the choice of the appropriate nominal system. Since it is assumed that the perturbations are about this nominal, the extent of allowed perturbation to maintain the stability and/or performance very much depends on this ‘nominal' system. Therefore, it is evident that this nominal system must have superior robustness properties. Incorporating certain robustness measures proposed in the literature, control design techniques have been realized in state space framework. However, the variety of controllers in state space framework is not as large as that of robust control design methods in frequency domain. Even these very few methods tend to be complex and demand some specific structure to the real parameter uncertainty (such as matching conditions). Overall, the success of all these methods for application to complex aerospace systems is still a subject of debate. Hence, there is still significant interest in designing robust controllers which can perform better than the existing controllers. Addressing these issues, current research proposes that the stability robustness measures for parameter perturbation are considerably improved if the ‘nominal' system is taken (or driven) to be a ‘sign stable' system. Motivated by this observation, a new method for designing a robust controller for linear uncertain state space systems is proposed. The novelty of this research lies in the incorporation of ecological principles in order to design robust controllers for engineering systems. It is observed that an ecological perspective gives better understanding of the dynamics of the open and closed loop system (nominal) matrices. One of the attractive features of this (open full item for complete abstract)

Committee: Rama K. Yedavalli PhD (Advisor); Meyer Benzakein PhD (Committee Member); Hooshang Hemami PhD (Committee Member) Subjects: Aerospace Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2007, Fenn College of Engineering

Cryogenic fluid systems are fundamental to space flight architecture. Due to the unique properties of cryogenic fluids and the environments in which they operate for space flight, cryogenic fluid management systems must be developed to maintain these fluids at conditions in which they can be utilized. Liquid oxygen boils at 90 K, and liquid hydrogen boils at 20 K. Significant care must be taken to provide a thermal management system that prevents heat entering these fluids with consequential adverse effects on the performance of the cryogenic fluid systems. One critical component of a cryogenic thermal management system is a Joule-Thomson device. This one small component provides the driving force not only for the production of cryogenic fluids, but for the effective management of thermal loads in many cryogenic fluid systems including those used in space flight architectures. As a fundamental understanding of the Joule-Thomson effect and J-T devices is critical to the effective design of cryogenic fluid management systems, the intent of this work is to examine J-T devices as they relate to space flight systems. This work will examine where these devices are used in space based cryogenic fluid management systems. It will consider research conducted to date that examines both the fundamental fluid physics behind how these devices operate and their application in real systems. Finally, it will report on the potential impact that fluid metastability has as it relates to J-T devices for certain cryogenic fluids. An analytical assessment is made of the stability limits of single phase cryogenic fluids as a J-T device operates on them. This is compared to experimental results for tests conducted in liquid oxygen, and liquid methane. Results show that several factors influence the performance of J-T devices, and that the metastability of single phase cryogenic fluids below the saturation line must be considered in the design of cryogenic fluid management systems.

Committee: Jerzy Sawicki (Advisor) Subjects: