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Space Systems Design Laboratory (SSDL)

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Now showing 1 - 10 of 622
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    Space Object Tracking from CubeSats utilizing Low-Cost Software Defined Radios
    (Georgia Institute of Technology, 2023-12) Mealey, Alex
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    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).
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    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.
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    Satellite Orbit Classification through Machine Learning
    (Georgia Institute of Technology, 2023-08) Kalidindi, Lakshmi Kundana
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    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.
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    The Orbital Calibration 2 (OrCa2) CubeSat Mission
    (Georgia Institute of Technology, 2023-08) Gunter, Brian C. ; Gregoire, Alaric ; Badura, Gregory ; Valenta, Christopher
    The Georgia Institute of Technology (Georgia Tech), in collaboration with the Georgia Tech Research Institute (GTRI), has developed the Orbital Calibration 2 (OrCa2) mission in an effort to improve space domain awareness. OrCa2’s external panels have precise and well-characterized reflective properties that will permit various calibration activities from ground-based optical sensors, with the goal of improving the tracking and detection of resident space objects (RSOs). OrCa2 is a 12U CubeSat designed, fabricated, assembled, and tested almost entirely in-house using GT/GTRI facilities. It will be regularly observed using Georgia Tech’s Space Object Research Telescope (GT-SORT). A number of experiments can be conducted with these measurements, such as pose estimation, validation of RSO trajectory propagations with complementary ground-based laser ranging data, multi-spectral analysis, low-light detection algorithms, and validation of atmospheric scattering models. An onboard imager will serve as both a low-accuracy star camera, as well as an on-orbit optical tracking system capable of RSO streak detection, with a mission goal of gathering simultaneous ground-based and space-borne tracking data of one or more RSOs. Additionally, the OrCa2 spacecraft will host an experimental radiation dosimeter, an experimental software defined radio (SDR) receiver, and an experimental power system. OrCa2 is currently manifested to launch in Q1 2024. An overview of the design, concept of operations, and expected outcomes of the mission will be presented.
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    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.
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    Lunar Crater Identification using Triangle Reprojection
    (Georgia Institute of Technology, 2023-08) Thrasher, Ava C. ; Christian, John A. ; Molina, Giovanni ; Hansen, Michael ; Pelgrift, John Y. ; Nelson, Derek S.
    Image-based terrain relative navigation is a critical capability for future lunar exploration missions. Images of the lunar surface containing craters can be compared to on-board maps to identify craters and estimate the spacecraft position. While there are many ways to accomplish the crater identification task, this work explores a method using triangulation and crater triangle pattern projections. Specifically, potential matching crater patterns from the catalog and image are used to triangulate the spacecraft position, allowing for construction of line-of-sight directions to the potential matching catalog craters. The projection of these directions in the image can be compared to the observed craters to accept or reject the match hypothesis. In this paper, we demonstrate the algorithm's capability in handling various types of input errors and what tolerances can be tuned to achieve a desired performance. Additionally, an initial look at flight software implementation is included.
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    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.