Organizational Unit:

Daniel Guggenheim School of Aerospace Engineering

Permanent Link

https://hdl.handle.net/1853/70742

Parent Organization

Organizational Unit

College of Engineering

Includes Organization(s)

Organizational Unit

Aerospace Design Group

Organizational Unit

Aerospace Systems Design Laboratory (ASDL)

Organizational Unit

Air Transportation Laboratory

Organizational Unit

Cognitive Engineering Center

Organizational Unit

Space Systems Design Laboratory (SSDL)

Show 1 more

ArchiveSpace Name Record

https://finding-aids.library.gatech.edu/agents/corporate_entities/106

Full item page

Publication Search Results

Now showing 1 - 10 of 34

An Investigation of the Susceptibility and Practical Mitigation of Pitch-Roll Resonance in Fin-Stabilized Liquid Sounding Rockets

(Georgia Institute of Technology, 2024-04-29) Nagarajan, Rithvik

Sounding rockets are suborbital vehicles designed to carry scientific payloads and perform experiments in the upper atmosphere. Recently, there has been a focus on reusable liquid sounding rockets to allow faster launch rates and lower costs per mission. Georgia Tech’s Yellow Jacket Space Program aims to contribute to this field by developing a series of liquid rockets with the goal of launching a sub-orbital payload to the Karman line. One of these rockets, Darcy II, experienced a catastrophic anomaly mid-flight. Like other fin-stabilized sounding rockets, Darcy II was designed with a high length-to-diameter ratio for drag optimization. This made the craft susceptible to roll-yaw resonance, where the vehicle spins close to the pitch natural frequency. Previous literature has shown roll-resonant vehicles can exhibit abnormal rolling and yawing motion beyond predictions by linear theory. Referred to as roll lock-in and catastrophic yaw, respectively, these effects can cause an excessive angle of attack and induce high structural loads. This thesis investigates the susceptibility of liquid sounding rockets to roll resonance, using the Darcy-Series rockets as case studies. Drawing from previous literature on roll resonance dynamics, additions are made to a 6DOF numerical simulation – integrating fluid models, configurational asymmetries, and non-linear aerodynamics with Monte Carlo variables. A sensitivity analysis on model components highlights characteristics of liquid rockets that influence roll resonance. This research examines the contribution of roll resonance to the Darcy II anomaly and through this, validates the numerical simulation. Subsequently, a Monte Carlo simulation is established as a practical method to assess the susceptibility of future liquid sounding rocket designs to the roll resonance phenomenon. This method is applied to the Darcy Space design, revealing a high susceptibility to roll resonance. Mitigation strategies are presented by analyzing the effect of fin design and configurational asymmetries on simulation outputs. Additionally, a simple roll control scheme is designed that takes advantage of existing liquid rocket infrastructure. Four attitude control thrusters are fired once in pairs, implementing a bang-bang roll control scheme designed to prevent roll lock-in using minimal amounts of propellant. This research evaluates the effectiveness of this control system in mitigating roll resonance issues.
VISORS Mission Orbit & Dynamics Simulation Using a Realtime Dynamics Processor

(Georgia Institute of Technology, 2023-12-01) Kimmel, Elizabeth

VIrtual Super-resolution Optics using Reconfigurable Swarms (VISORS) is a precision formation-flying mission which uses two 6U CubeSats with a Science Mode separation distance of 40 meters to emulate a 40-meter focal length diffractive optic telescope. Due to the novelty of the technology used to achieve the stringent relative positioning requirements, the dynamics of these orbits must be simulated to verify the concept of operations (ConOps), the commercial spacecraft bus flight software (FSW), the guidance, navigation, and control (GNC) formation-keeping algorithm, and the attitude determination and control system (ADCS) performance, among others. Verifying these aspects helps ensure that issues such as reaction wheel saturation, pointing errors, or collision risks, among others, do not arise during the mission. This paper describes the work done in simulating the spacecraft dynamics during the mission’s Science Operations using COSMOS to interface with the Realtime Dynamics Processor (RDP) and spacecraft bus Engineering Design Unit (EDU) provided by Blue Canyon Technologies (BCT).
Development of an Autonomous Distributed Fault Management Architecture for the VISORS Mission

(Georgia Institute of Technology, 2023-08-01) Paletta, Antoine

CubeSat formations have been identified as a new paradigm for addressing important science questions, but are often early adopters of new technologies which carry additional risks. When these missions involve proximity operations, novel fault management architectures are needed to handle these risks. Building on established methods, this paper presents one such architecture that involves a passively safe relative orbit design, interchangeable chief-deputy roles, a formation level fault diagnosis scheme, and an autonomous multi-agent fault handling approach. This architecture focuses on detecting faults occurring on any member of a spacecraft formation in real time and performing autonomous decision making to resolve them and keep the formation safe from an inter satellite collision. The NSF-sponsored Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) mission, which consists of two 6U CubeSats flying in formation 40 meters apart as a distributed telescope to study the solar corona, is used as a case study for the application of this architecture. The underlying fault analysis, formulation of key elements of the fault detection and response strategy, and the implementation as flight software for VISORS are discussed in the paper.
Performance of a low infrastructure navigation system for planetary surface users

(Georgia Institute of Technology, 2023-07-25) Jun, William W.

With the plan to return to the Moon, there is great interest in a sustained lunar presence by both autonomous vehicles and humans. Establishing a lunar presence necessitates an accurate lunar navigation service that is scalable in user quantity. Future lunar users will require onboard, real-time position, velocity, and timing (PVT) estimation. This research proposes a low infrastructure, radiometric navigation system to fulfill this need. This thesis first introduces a set of Doppler-based navigation methods to enable positioning of lunar surface users with a low infrastructure navigation architecture. Combined with range measurements and a well-known reference station, these methods create Joint Doppler and Ranging (JDR) navigation. JDR reduces errors in Doppler measurements through geometric constraints between the user, reference station, and orbiter. This provides effective position estimation using Doppler measurements. Then, to mitigate biases in frequency measurements, this research introduces measurement differencing with JDR. To evaluate the performance of JDR with realistic Doppler measurements, this thesis develops a comprehensive Doppler shift measurement simulation that generates frequency biases, drifts, and noise based on a high-fidelity oscillator model. This oscillator model develops integrated frequency errors from commercial oscillator phase noise data. Case studies establish performance of JDR with various grades of local oscillators onboard the users and the navigation orbiters. Finally, this thesis generalizes JDR for dynamic users, enabling real-time PVT estimation. The generalized JDR method with measurement differencing effectively navigates a user along a challenging trajectory on the lunar surface. A case study demonstrates orbit determination of a low lunar orbiter with JDR. The use of one-way radiometric measurements results in a scalable navigation architecture that can service any user in the reference station's region. This research advances the navigation capabilities of future lunar missions. With its low infrastructure navigation architecture, JDR is applicable as navigation service for other target planets, such as Earth and Mars.
Development of an Autonomous Distributed Fault Management Architecture for the VISORS Mission

(Georgia Institute of Technology, 2023-05-01) Paletta, Antoine

CubeSat formations have been identified as a new paradigm for addressing important science questions, but are often early adopters of new technologies which carry additional risks. When these missions involve proximity operations, novel fault management architectures are needed to handle these risks. Building on established methods, this paper presents one such architecture that involves a passively safe relative orbit design, interchangeable chief-deputy roles, a formation level fault diagnosis scheme, and an autonomous multi-agent fault handling approach. This architecture focuses on detecting faults occurring on any member of a spacecraft formation in real time and performing autonomous decision making to resolve them and keep the formation safe from an inter satellite collision. The NSF-sponsored Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) mission, which consists of two 6U CubeSats flying in formation 40 meters apart as a distributed telescope to study the solar corona, is used as a case study for the application of this architecture. The underlying fault analysis, formulation of key elements of the fault detection and response strategy, and the implementation as flight software for VISORS are discussed in the paper.
Lessons Learned in University Production of CubeSat Propulsion Systems

(Georgia Institute of Technology, 2023-05-01) Glaser, Mackenzie J.

The Space Systems Design Lab (SSDL) at the Georgia Institute of Technology (GT) designs and manufactures propulsion systems for CubeSats using green monopropellant and cold gas propulsion technologies. Over the history of building these systems, a variety of off-nominal behaviors and nonconformances have been observed including contamination by foreign object debris, higher than acceptable leak rates, and inconsistent performance. Root cause investigations have been conducted where appropriate for individual systems and the identified root causes have included manufacturing defects, incomplete cleaning processes, and improper parts sizing. This paper collects and identifies historic off-nominal behaviors and nonconformances observed in SSDL-built propulsion systems and discusses the investigations of the root causes of these behaviors. These root cause issues are outlined and compared to present suspected systemic issues in propulsion system production. Root cause issues on each unit are added up based on the larger category of cause including design, assembly and test processes, or facilities used to conduct these processes. Frequency of causes over the whole propulsion program are used to confirm trends in root causes. Based on these trends, best practices are highlighted to prevent failures on future systems and ensure the highest possible quality of hardware.
Refill Strategy for Two Tank Gold Gas Propulsion Systems

(Georgia Institute of Technology, 2023-05-01) Wood, Samuel

Cold gas propulsion systems using a saturated liquid-vapor mixture as propellant often use separate tanks for storage and actuation. The pressure of a plenum is regulated via refills from a storage tank. Without a propellant management device, simple pressure-controlled refills can inject unwanted liquid into the plenum. This phenomenon leads to unpredictable thrust and a lower-than-expected specific impulse. These undesirable characteristics are mitigated by using a model-based closed-loop refill strategy. A valve flow equation is combined with system characterization data to approximate the average mass flow between the storage tank and plenum. Refill valve opening and closing times are controlled to allow the system to reach steady state prior to refilling or actuating. Controller operation is tested and validated on integrated cold gas systems in orientations that allow either liquid or gas to be in contact with the plenum refill port. These simulated worst-case and best-case on-orbit conditions are tested across the system’s full temperature operating range. This paper describes the model development, integrated hardware testing, and improved system performance associated with the model-based plenum refill strategy. These findings enable two-tank cold gas propulsion systems using pressure-controlled refilling to deliver more repeatable system operation.
Operations Systems Engineering for the Lunar Flashlight Mission

(Georgia Institute of Technology, 2023-05-01) Hauge, Michael

Lunar Flashlight, a 6U CubeSat developed by NASA’s Jet Propulsion Laboratory (JPL) and operated by students at the Georgia Institute of Technology (GT), was launched in December 2022 with a mission to demonstrate novel small satellite technologies, including a first-of-its-kind green monopropellant system, and to map surface water ice in permanently shadowed regions of the lunar south pole using near-infrared laser reflectometry. While responsible for tactical operation of the spacecraft, including commanding and telemetry monitoring, GT students have also taken on strategic roles as operations systems engineers. The team has maintained, developed, and refined models of spacecraft subsystems as well as coordinated the project’s approach to anomaly response and fault protection. This paper reports how flight data and post-launch experiences have influenced the development and refinement of these models and approaches, and how in turn this systems engineering work has allowed the team to make more efficient use of the spacecraft’s capabilities, especially in dynamic anomalous situations, by taking advantage of margins, synthesizing data, and adapting flight rules and constraints. In-flight anomalies have required substantial rework of the mission’s concept of operations, and anomaly management and resolution has leaned heavily on modeling and predictions from the operations systems engineers. Working closely with JPL subject matter experts, the GT operations team has made full use of available data, including telemetry and observed system behavior, to swiftly recognize and address anomalies, support strenuous recovery efforts, and make possible a realignment of the concept of operations to achieve mission success despite significant challenges.
Deep Space Relay Architecture for Communication and Navigation

(Georgia Institute of Technology, 2023-05-01) Carter, Paul

The Deep Space Relay architecture explored in this paper is intended to provide communication and navigation services to Mars surface users and spacecraft in the Mars vicinity. The relay orbiters making up this architecture will be placed in strategic heliocentric orbits near Mars so as to mitigate the Mars superior conjunction problem for optical communications, and at the same time provide a good geometry for deep space navigation. Design trades are performed to ensure that the relay architecture is optimal in its roles as both a communication provider and navigation provider. Geometric constraints are identified that allow the relay architecture to provide continuous optical link coverage throughout the time period from 2030-2060. An optimal and minimal relay architecture is identified that meets these geometric constraints while also maximizing the data return of the optical link and providing a suitable geometry for trilateration-based navigation with the fewest relay orbiters possible. The communication performance of this optimal relay geometry is assessed through an analysis of the additional access time and data return it provides. On the navigation side, the performance of the optimal architecture is assessed based on access and a geometric dilution of precision (GDOP) analysis. An expanded architecture is introduced which adds a relay in a Mars halo orbit to the minimal architecture for additional communication and navigation benefits.
Application of model predictive control for the autonomous rendezvous and docking of small satellites

(Georgia Institute of Technology, 2023-04-26) Fear, Andrew

Autonomous rendezvous and docking (AR&D) maneuvers are a key enabling technology for many types of space missions. For example, in the realm of small satellites it would facilitate on-orbit construction of larger assemblies. The volume and mass limit constraints are a crucial challenge imposed by the form factor. First, the presented work details a three-phase model predictive control (MPC) algorithm. MPC provides robustness to uncertainties in the dynamics and utilizes optimal control techniques that can handle state and control constraints directly. The three phases highlight changing constraint conditions within the underlying optimal control problem. Second, the work provides a detailed analysis of the implemented algorithm to changing parameters and tests the overall robustness to actuation uncertainties. A simulation specific to the AR&D of small satellites was created to assess the MPC algorithm. Rendezvous to a non-maneuvering target has been considered for both non-rotating and constant tumbling cases. Finally, hardware emulation is used to verify that the proposed guidance algorithm is capable of running onboard a flight computer analog. The computational performance is benchmarked for a couple of parameters to investigate the effect on performance.