Astrodynamics Commons^™

Data-Driven Learning Algorithms To Predict Spacecraft Trajectories In The Dro Family, Sarath Murarisetty, Hansaka Aluvihare Aluvihare, Oshani Jayawardane, Annika Anderson

Discovery Day - Daytona Beach

Generating precise, accurate, and efficient trajectories in the Earth-Moon circular restricted three-body problem (CR3BP) is crucial for long-term lunar missions, yet it remains challenging. A primary reason for this is that the CR3BP is an extremely nonlinear and chaotic system. Fortunately, neural networks present a promising approach for addressing such complex nonlinear challenges. In “Data-driven Learning Algorithms to Predict Spacecraft Trajectories in the DRO Family,” this work addresses the challenge of solving a nonlinear system within the CR3BP framework to determine the trajectories of spacecraft within the Distant Retrograde Orbit (DRO) family using neural networks (NNs). For a comprehensive comparison …

N31 Multi-Sensor Data Fusion For Enhanced Cislunar Space Domain Awareness Using Radar And Optical Observations, Lucas Bottero

Discovery Day - Daytona Beach

MULTI-SENSOR DATA FUSION FOR ENHANCED CISLUNAR SPACE DOMAIN AWARENESS USING RADAR AND OPTICAL OBSERVATIONS   As operations extend into cislunar space, maintaining Space Domain Awareness (SDA) becomes increasingly challenging due to the vast distances, sparse infrastructure, and complex gravitational dynamics between Earth and the Moon. Radar and optical sensors are the primary modalities used for space surveillance, each with its strengths and limitations. Radar offers continuous observation capabilities regardless of lighting conditions but is limited by power and range at cislunar distances. Optical sensors provide high angular precision but depend on favorable illumination and line-of-sight geometry. However, there has been limited …

Modeling A Spaceborne Passive Radar Architecture For Tracking Resident Space Objects Using Ground-Based Signals Of Opportunity, Chinmay Gaikwad

Discovery Day - Daytona Beach

Modeling a Spaceborne Passive Radar Architecture for Tracking Resident Space Objects Using Ground-Based Signals of Opportunity Due to an increase in manned and unmanned space activities, there is an increase in demand for resilient space operations. This project investigates passive-radar architecture for space domain awareness in which satellites in a low-Earth-orbit mega-constellation are adapted as distributed sensing platforms for tracking debris and other non-cooperative resident space objects. The motivation is to overcome the coverage, cost, and scalability limits of conventional active or ground-based systems by using lightweight passive receivers that exploit ground-based illuminators of opportunity. In this concept, the receivers …

Sun-Synchronous Low Earth Orbit Missions For Imaging Applications, Isaac Rosenthal

Discovery Day - Daytona Beach

Orbit and mission design are crucial elements that must be considered to achieve Earth observation data for land monitoring. This project examines the sun-synchronous low Earth orbit (LEO) implementations of missions with similar objectives: NASA’s Landsat 8 and ESA’s Sentinel-2 constellation. The purpose of this study is to evaluate how differing mission designs, impact imaging and coverage capabilities. Key design trade offs between the two missions include altitude effects on atmospheric drag and station-keeping, swath width versus field-of-view choices, and a single, centralized spacecraft architecture versus a multi-satellite distributed system. This is accomplished by analyzing different orbital parameters, ground track …

Evaluation Of Orbit And Mission Design Parameters Considered In Real Space Missions, Enrique Alejandro Amaya Villegas

Discovery Day - Daytona Beach

Orbit and mission design constitute a fundamental spacecraft subsystem, as the selected orbital regime and mission profile strongly influence power availability, communications geometry, propulsion requirements, and overall mission performance. This project investigates how key quantitative and qualitative parameters guide orbit and mission design decisions in real space missions, with particular emphasis on orbital altitude and inclination, ground coverage and revisit time, mission lifetime, launch vehicle performance constraints, and propulsion budgets. The primary objective is to develop a structured understanding of how high-level scientific or commercial objectives, together with cost, risk, and operational constraints, are translated into specific orbital architectures and …

Interplanetary Trajectory Optimization With Reinforcement Learning, Shiloh Cuffe

Discovery Day - Daytona Beach

This project investigates the application of reinforcement learning (RL) to optimize low-thrust interplanetary trajectory design, focusing on the Earth-Venus transfer leg of the BepiColombo mission. Traditional trajectory optimization methods, such as patched conics and genetic algorithms, often require simplifying assumptions or complex optimization schemes. This work formulates the trajectory design problem as an optimal control problem (OCP) within a Markov Decision Process (MDP) framework, enabling an RL agent to learn efficient transfer strategies under realistic spacecraft constraints. The objective is to develop an autonomous guidance approach capable of replicating or improving upon established mission designs. The spacecraft is modeled as …

Gravity Gradient Exploration Satellite, Luke Ritchie, Isaac Rosenthal, Benjamin Mason, Nathaniel O’Hara

Discovery Day - Daytona Beach

The Gravity Gradient Exploration Satellite (GGEOS) is a single-unit CubeSat technology demonstration being developed by a group of four undergraduate aerospace engineering students at Embry-Riddle Aeronautical University. The mission is designed to validate a controlled, motor-driven, semi-rigid space-tether and deployment system. Space tethers offer significant potential for gravity gradient stabilization and propellant-less electrodynamic propulsion, however past missions have frequently failed due to rebound and tangling from their spring-based deployment systems and elastic tethers. GGEOS mitigates these challenges using a semi-rigid, tape-measure-like tether, deployed with a stepper-motor-driven extrusion system enabling slow, controlled deployment and reduced post-deployment problems. The spacecraft architecture utilizes …

Engineering Path Trajectories With Gravitational Fields, Eliane Dean, Aidan Hart, Isabel Noot, Nathan Browning, Valeria Villazon Fito

Discovery Day - Daytona Beach

This project explores how vector calculus concepts play a role in aerospace engineering though spacecraft trajectory design. In particular, the notion of vector fields is used to model the gravitational force, whose work done is expressed through line integrals. By taking the curl of the gravitational field and showing it is zero, the field is recognised as conservative, implying that the work done by gravity is path independent. This property is conceptually linked to gravitational potential energy and the principle of energy conservation. The results are then applied to spacecraft motion, where engineers use energy-base methods to determine efficient trajectories …

Feasibility And Performance Of Aerogravity Assists For Ceres Missions, Divinaa E. Burder

International Journal of Aviation, Aeronautics, and Aerospace

This work investigates the feasibility and performance of aerogravity assist (AGA) maneuvers for missions to Ceres, with emphasis on both interplanetary trajectory design and atmospheric flight dynamics. AGAs provide substantially greater turning capability than pure gravity assists by exploiting aerodynamic lift during atmospheric passes, thereby enabling greater heliocentric energy changes than pure gravity assists. To quantify these benefits, this study integrates a broad interplanetary trajectory search with high-fidelity atmospheric performance modeling. Candidate trajectories for launch years 2030–2050 are generated for multiple inner-planet encounter sequences using vehicles with lift-to-drag ratios (L/D) between 1 and 7. Atmospheric flight segments are simulated using …

Prediction Of Satellite Temperature During An Orbit Of A Cubesat, Michael Reynolds

Honors Theses

This thesis develops a thermal-simulation strategy for predicting CubeSat component temperatures, applied to Jag-Sat-1, a CubeSat developed at the University of South Alabama and deployed from the International Space Station in 2022. The orbit was reconstructed from two-line element (TLE) data using simplified general perturbations (SGP4) propagation, and spacecraft attitude was recovered from onboard gyroscope measurements. Sunlight, penumbra, and umbra intervals were computed geometrically, and the external radiative environment — direct solar, Earth infrared, and albedo heat fluxes — was modeled using orientation-dependent view factors. These time-varying fluxes drove a transient finite-element thermal simulation of the full satellite geometry in …

Compact Cislunar Orbital Representation For Efficient Tracking In Cislunar Space, Mauro Palomo

Doctoral Dissertations and Master's Theses

Expanding lunar missions require efficient, interoperable orbital tracking where existing methods fail to scale. Two-Line Elements (TLEs) lack applicability beyond geocentric regimes, while high-accuracy Orbit Ephemeris Messages (OEMs) require excessive data volumes and bandwidth to communicate. To support increased lunar traffic, this paper proposes the Compact Cislunar Orbital Representation (CCOR), providing a novel framework that strikes a balance between TLE level efficiency and OEM-level fidelity, ensuring multi-actor communication for missions in the cislunar region. By evaluating the framework across six diverse cislunar trajectories, this study demonstrates the CCOR’s robustness and ability to compress thousands of OEM state vectors into a …

Optimization Of Repeat Ground Track Constellation Design For Complex Discontinuous Regional Coverage, Paige Jewell

Master's Theses

The continued growth of low Earth orbit (LEO) satellite constellations motivates efficient constellation design methods to reduce cost and complexity. Although brute-force methods are commonly employed in the preliminary design of satellite constellations, pairing analytic methods with optimization algorithms provides a more efficient means of searching the design space. Constellation design for continuous global and regional coverage is well-established; however, strategies for discontinuous regional coverage remain underdeveloped. This thesis focuses on an analytic geometry-based method for computing satellite coverage and revisit metrics, coupled with genetic algorithm optimization to efficiently explore the design space. The viability of this method is shown …

Short Arc Angles-Only Initial Orbit Determination For Reliable Reacquisition Of Low Earth Orbit Objects, Isabella Rackemann

Master's Theses

Low Earth orbit (LEO) is becoming increasingly congested, furthering the need for accurate tracking and catalog maintenance. Initial orbit determination (IOD) is the first step in this process, providing a preliminary estimate of an object’s state given observations. When it comes to LEO optical observations, a large portion of them are inherently short in duration. Angles-only IOD methods struggle with this data, often producing highly inaccurate solutions that limit reacquisition capabilities. This study expands on prior short arc IOD research, testing seven classical and assumed circular orbit (ACO)-modified angles-only IOD algorithms on real LEO observational data spanning 0-4 degrees of …

Effects Of Atmospheric Drag On Angles-Only Initial Relative Orbit Determination Accuracy In Low Earth Orbit, Sydney Walsh

Master's Theses

Growing congestion in low Earth orbit is increasing the demand for effective space situational awareness, straining ground station capabilities. Space-based relative orbit determination offers an alternative, using line-of-sight angle measurements from a chaser spacecraft to estimate a target spacecraft's orbit. This research focuses on angles-only initial relative orbit determination (IROD), where no prior target state knowledge is assumed. It investigates how IROD solution accuracy is affected by differential atmospheric drag between the chaser and target spacecraft. A nonlinear batch least squares filter is designed to estimate the target's initial state, which is compared against a truth solution. It was found …

A Polygon Approach For Satellite Coverage Computation Problems, Caleb I. Arbreton

Master's Theses

During celestial body observation mission planning, predicted sensor coverage is a key analysis tool used by designers to inform concept of operations. It enables trade studies by applying a metric to assess how well different sensor, satellite, and constellation configurations can observe a mission's region of interest. The effectiveness of the studied components is then paramount in determining whether they are justified in the system architecture. Coverage computation becomes more difficult as sensor types and regions of interest (RoIs) deviate from simple shapes, and as problem formulations seek higher-fidelity results. These simplifications include: conical camera sensors, RoIs represented as simple, …

Adaptive Control Combined With Integral Concurrent Learning For Trajectory Tracking Near Asteroids, Alvaro Diaz Rodrigo

Doctoral Dissertations and Master's Theses

Close-proximity operations in the vicinity of Near-Earth Asteroids (NEAs) are essential for scientific studies and possible future planetary-defense missions. Unlike motion around large celestial bodies, spacecraft dynamics near small, rotating asteroids are dominated by weak, highly irregular gravity fields. While full characterization of an asteroid’s shape enables high-fidelity gravitational modeling, such information is typically unavailable in realistic mission scenarios, and in-situ exploration is often required. As a result, the forces acting on the spacecraft cannot be modeled accurately in advance, leading to significant uncertainty in the equations of motion and challenging guidance and control strategies. To address these challenges, the …

Adaptive Artificial Potential Field Guidance And Control For Autonomous Docking With Uncooperative And Unknown Spacecraft, Steven Holmberg

Theses and Dissertations

The increasing demand for on-orbit servicing (OOS), active debris removal (ADR), and space domain awareness (SDA) missions has increased the need for autonomous spacecraft rendezvous and proximity operations (RPO) with uncooperative and unknown targets. Traditional guidance and control methods are typically designed for cooperative systems with known geometry and state information. This work builds on previous research to develop and evaluate an artificial potential field (APF)-based control framework capable of autonomous operation with minimal prior target knowledge and applicability to both relatively static and tumbling spacecraft.

The proposed APF formulation incorporates established safety constructs from cooperative docking systems, including an …

Adaptive Methods Of Resident Space Object Identification For Space Situational Awareness, Evan Pavetto-Stewart

Doctoral Dissertations and Master's Theses

One of the fundamental tenets of Space Situational Awareness (SSA) is the detection and sub sequent identification of Resident Space Objects (RSOs) within unresolved optical space imagery. This function is vital to the documentation and tracking of RSOs in their respective operational orbits, knowledge that is necessary for collision avoidance efforts and Space Domain Awareness (SDA) applications. In previous work, development was begun on a MATLAB program called RSOID to fulfill this purpose by accepting a collection (or ’collect’) of unresolved imagery and outputting a sequence of RSO locations (called a ’tracklet’) that can be used to determine the RSO’s …

Discovery Of Dynamical Structures Mapping Chaotic Transport Pathways In The Earth–Moon Cr3bp, Tyler J. Kapolka, Christina E. Paljug, Robert A. Bettinger, Rachel Oliver, Bruce A. Cox, Jeremiah A. Specht

Faculty Publications

Chaos; Deterministic chaos; Earth–Moon system; Poincaré map; Quasi-chaotic; Surface of section /// For the Circular Restricted 3-Body Problem (CR3BP), the topologies present within a Poincaré map enable the extraction of useful information regarding periodic, quasi-periodic, and chaotic trajectory behavior. Aside from the prominent topologies that follow distinct concentric patterns around fixed points, indicative of the periodic and quasi-periodic motion that is often the central focus of CR3BP research, there are also many “dusty” regions on the Poincaré map that appear random without an apparent structure and are indicative of chaotic motion. This paper, for the first time in literature, identifies …

Simulation Results Of Spaceborne Ssa Using A Comprehensive Passive Radar Model, Chinmay Gaikwad, Filipe Senra, Thomas Alan Lovell, Hao Peng, Berker Pekoz, Tianyu Yang

Publications

In this paper, a high-fidelity simulation framework is developed to assess the feasibility of tracking space debris using a large low-Earth orbit (LEO) satellite constellation equipped with onboard passive radar sensors. By exploiting illumination from a distributed network of ground-based transmitters, the constellation provides consistent line-of-sight access to debris objects at higher altitudes, enabling angles-only detection and tracking. This approach yields a scalable, automated, and cost-effective architecture for next-generation space surveillance and contributes to more resilient space traffic management. A complete angles-only passive-radar orbit-determination pipeline is introduced and demonstrated. Initial orbital states are generated using a rate-aware constrained admissible-region multiple-hypothesis …