Person:

Lightsey, E. Glenn

Permanent Link

https://hdl.handle.net/1853/71462

Associated Organization(s)

Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

Organizational Unit

Space Systems Design Laboratory (SSDL)

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Publication Search Results

Now showing 1 - 10 of 42

Design of the Hosted Software Application for the VISORS Mission

(Georgia Institute of Technology, 2023-08) Arunkumar, Ebenezer ; Paletta, Antoine ; Lightsey, E. Glenn

The VIrtual Super Optics Reconfigurable Swarm (VISORS) mission is a distributed space telescope consisting of two 6U CubeSats that utilize precision formation flying to detect and study the fundamental energy release regions of the solar corona. The inherent complexities and risks associated with two spacecraft operating in close proximity, as well as the unique restrictions of the spacecrafts’ design, make careful autonomous execution crucial to the success of the mission. To address these challenges, this paper outlines the development of the Hosted Software Application (HSA) flight software which manages the Guidance, Navigation, and Control (GNC) algorithms, the payload finite state machine, and the spacecraft and formation level fault management system. An overview of the HSA provides context for the motivation and requirements driving the design of the flight software system. The architecture of the HSA is presented and shown to be derived from the Mission Events Timeline (MET) for each of the relevant phases of the mission. Finally, this paper briefly discusses the software's implementation and test campaign.
Development of an Autonomous Distributed Fault Management Architecture for Spacecraft Formations Involving Proximity Operations

(Georgia Institute of Technology, 2023-08) Paletta, Antoine ; Arunkumar, Ebenezer ; Lightsey, E. Glenn

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 strategy. The primary focus is to enable the reliable detection of faults occurring on any formation member in real time and the autonomous decision making needed to resolve them while keeping 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 solar telescope, 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 strategies, and the flight software implementation for VISORS are discussed in the paper.
Design to Delivery of Additively Manufactured Propulsion Systems for the SWARM-EX Mission

(Georgia Institute of Technology, 2023-08) Tong, Kevin ; Hart, Samuel T. ; Glaser, Mackenzie ; Wood, Samuel ; Hartigan, Mark C. ; Lightsey, E. Glenn

Recent progress in miniaturized spacecraft propulsion technology has allowed for the development of complex, multi-vehicle missions which enable the cost-effective realization of science goals that would previously have been prohibitively expensive. The upcoming NSF-funded Space Weather Atmospheric Reconfigurable Multiscale EXperiment (SWARM-EX) mission leverages these swarm techniques to demonstrate novel autonomous formation flying capabilities while characterizing the spatial and temporal variability of ion-neutral interactions in the Equatorial Ionization Anomaly and Equatorial Thermospheric Anomaly. SWARM-EX will fly a trio of 3U CubeSats in a variety of relative orbits with along-track separations ranging from 3 km to 1300 km. To achieve the required orbital variability, the mission uses a novel hybrid approach of differential drag and an onboard cold gas propulsion system. Mission requirements necessitate a propulsion system that provides each spacecraft with 15 m/s of ΔV and a maximum thrust greater than 5 mN in a volume of roughly 0.7U (7 cm x 10 cm x 10 cm). Unlike many other CubeSat-scale cold gas propulsion systems which are used to provide attitude control and perform reaction wheel desaturation burns, the primary objective of the SWARM-EX propulsion system (SEPS) is to provide ΔV during maneuvers. The Georgia Institute of Technology Space Systems Design Laboratory (SSDL) is conducting the design, assembly, and testing of three identical SEPS. By leveraging additive manufacturing technology, the propellant tanks, nozzle, and tubing are combined into a single structure that efficiently utilizes the allocated volume. The propulsion system uses two-phase R-236fa refrigerant as a propellant, which allows for the storage of the majority of propellant mass as a liquid to maximize volumetric efficiency. The final design allows for 17 m/s of total ΔV per spacecraft and a measured maximum thrust of approximately 35 mN for short pulse lengths at room temperature. Each individual propulsion system has a volume under 0.5U (489 cm3), making them among the smallest formation-flying CubeSat-scale propulsion systems developed thus far. Owing to their two-phase propellant storage and single nozzle, the SEPS have a high impulse density (total impulse provided per unit of system volume) of 176 N-s/L. Additionally, process improvements to mitigate known failure modes such as propellant leaks and foreign object debris are implemented. This paper describes the entire design-to-delivery life cycle of the SWARM-EX propulsion units, including pertinent mission requirements, propulsion system design methodologies, assembly, and testing. Major lessons learned for future small satellite propulsive endeavors are also detailed.
Model Predictive Path Integral Control for Spacecraft Rendezvous Proximity Operations on Elliptic Orbits

(Georgia Institute of Technology, 2023-08) Sasaki, Tomohiro ; Ho, Koki ; Lightsey, E. Glenn

This paper presents a nonlinear control framework for spacecraft rendezvous and proximity operations on elliptic orbits using Model Predictive Path Integral (MPPI) control. Path integral control is a sampling-based nonlinear stochastic optimal control algorithm that can avoid linear and quadratic approximations in both dynamics and cost functions. While this control method has gained popularity in the robotics community due to its algorithmic effectiveness, it remains unexplored in astrodynamics. This paper demonstrates a comprehensive closed-loop simulation of spacecraft rendezvous employing MPPI and evaluates its control performance through these simulations.
The Journey Of The Lunar Flashlight Propulsion System From Launch Through End Of Mission

(Georgia Institute of Technology, 2023-08) Smith, Celeste R. ; Cheek, Nathan ; Burnside, Christopher ; Baker, John ; Adell, Philippe ; Picha, Frank ; Kowalkowski, Matthew ; Lightsey, E. Glenn

The Lunar Flashlight Propulsion System (LFPS) was developed as a technology demonstration to enable the Lunar Flashlight spacecraft to reach Lunar orbit and to desaturate onboard reaction wheels. While the system produced over 16 m/s of delta-v and successfully managed momentum, variable thrust performance, most likely due to debris in the propellant flow path, kept the spacecraft from reaching the Moon. This paper details the in-flight journey of the LFPS, highlighting both successes and challenges met throughout the mission, and provides lessons learned applicable to future CubeSat missions and additively manufactured propulsion systems.
Optimization of Early-Phase Cislunar Navigation Constellations for Users Near the Lunar South Pole

(Georgia Institute of Technology, 2023-08) Hartigan, Mark C. ; Smith, Dillon ; Lightsey, E. Glenn

To meet the needs of burgeoning global scientific and strategic interest in cislunar space, organizations such as NASA and the ESA have expressed interest in establishing a cislunar-based position, navigation, and timing (PNT) system. Minimal system implementations (defined as between 4 and 8 satellites) will provide critical PNT services to near-term cislunar missions and set the stage for constellation expansion and the establishment of a global lunar navigation service. This work proposes a set of fixed metrics through which cislunar PNT constellations can be evaluated, including: coverage, gap time, dilution of precision, user equivalent range error, and stationkeeping costs. Several minimal implementations that are proposed in literature are first examined, then optimized for certain design traits to improve system performance. Finally, simulations are conducted to compare constellation performance for end users - specifically ground stations and rovers.
Performance of a Model Predictive Control Based Autonomous Rendezvous and Docking Algorithm for CubeSats using Hardware Emulation

(Georgia Institute of Technology, 2023-02) Fear, Andrew J. ; Lightsey, E. Glenn

Hardware emulation of typical CubeSat flight computers is utilized to benchmark the performance of a three-phase Model Predictive Control (MPC) algorithm for autonomous rendezvous and docking (AR&D). The length of the MPC prediction horizons affects the computational complexity and therefore the solution time of finding an optimal control sequence. This study investigates the limitations, if any, of current state-of-the-art CubeSat flight systems regarding the ability to take advantage of this type of guidance algorithm. A virtual machine with an ARM processor typical of CubeSat available hardware is used to test the performance of the algorithm. Monte Carlo simulations are run to calculate the average computation time per optimal control solution and compare these values across varying prediction horizon lengths.
Testing Methodology For Spacecraft Precision Formation Flying Missions

(Georgia Institute of Technology, 2023-02) Kimmel, Elizabeth ; Paletta, Antoine ; Arunkumar, Ebenezer ; Krahn, Grace ; Lightsey, E. Glenn

Distributed space systems, and specifically spacecraft formations, have been identified as a new paradigm for addressing important science questions. However, when it comes to verifying and validating these systems before launch, there is the added challenge of figuring out how to test the formation's holistic operations on the ground since a full end-to-end mission simulation is likely infeasible due to the need for costly testing infrastructure/facilities. Building on established methods for single-spacecraft testing, this paper presents a two-phase testing methodology that can be applied to precision formation flying missions with budget, timeframe, and resource constraints. First, a testing plan with unique considerations to address the coordinated and coupled nature of precision formation flight is devised to obtain high system confidence on the ground, and second, the formation's holistic behavior is refined on orbit during the mission's in-space commissioning. This approach structures the pre-launch testing to make efficient use of the limited test infrastructure on hand and leverages a sequential configuration process combined with built-in operational flexibility on orbit to safely finish characterizing the formation's performance so that it can meet mission requirements.
Improvements on Two-Phase Cold Gas Propulsion Systems for Small Spacecraft

(Georgia Institute of Technology, 2023-02) Hart, Samuel T. ; Lightsey, E. Glenn

Small spacecraft such as CubeSats are being used to accomplish increasingly complex missions requiring precise relative positioning and maneuverability. This capability is often provided by cold gas propulsion systems, many of which use a two phase propellant. These systems have the benefit of being simple and inexpensive, but their capabilities are limited by the current technology. There is a need for a next generation of cold gas propulsion systems that are capable of improved performance relative to the heritage systems. This paper outlines the propulsion needs of future CubeSat missions, describes the shortcomings of current systems, and proposes a design concept for the next generation of cold gas propulsion units for use on small spacecraft missions. The key areas for improvement are identified as propellant management, temperature compensation, manufacturing, leak mitigation, and reliability. The proposed next-generation propulsion system, referred to as GTCG2, aims to improve in these areas through the use of advanced additive manufacturing, a novel propellant management system, closed-loop temperature control, and redundancy of key components. This architecture will allow for increased reliability, repeatability of impulses, and impulse density while maintaining a low cost.
Systems Integration and Test of the Lunar Flashlight Spacecraft

(Georgia Institute of Technology, 2022-08) Cheek, Nathan ; Gonzalez, Collin ; Adell, Philippe ; Baker, John ; Ryan, Chad ; Statham, Shannon ; Lightsey, E. Glenn ; Smith, Celeste R. R. ; Awald, Conner ; Ready, W. Jud

Lunar Flashlight is a 6U CubeSat launching in late 2022 or early 2023 that will search for surface water ice content in permanently shadowed regions at the south pole of the Moon using infrared relative reflectance spectroscopy. The mission will act as a technology demonstration of an Advanced Spacecraft Energetic Non- Toxic (ASCENT) green propulsion system and active laser spectroscopy within the CubeSat form-factor. This paper provides an overview of the entire Systems Integration and Test campaign which took place at the Jet Propulsion Laboratory and the Georgia Institute of Technology. From initial testing of the isolated avionics and payload subsystems to the final tests with a fully integrated spacecraft, the project’s integration and test campaign is reviewed, with a focus on lessons learned.