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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemRelative Positioning and Tracking of Tethered Small Spacecraft Using Optical Sensors(Georgia Institute of Technology, 2018-12) Guo, Yanjie
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ItemA Preliminary Assessment of the RANGE Mission's Orbit Determination Capabilities(Georgia Institute of Technology, 2018-08) Claybrook, Austin W.
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ItemProbabilistic Resident Space Object Detection Using Archival THEMIS Fluxgate Magnetometer Data(Georgia Institute of Technology, 2018-05-02) Brew, Julian ; Holzinger, Marcus J.Although the detection of Earth-orbiting space objects is generally achieved using optical and radar measurements, these methods are limited in the ca pability of detecting small space objects at geosynchronous altitudes. This paper examines the use of magnetometers to detect plausible flyby encoun ters with charged space objects using a matched filter signal existence binary hypothesis test approach on archival fluxgate magnetometer data from the NASA THEMIS mission. Relevant data-set processing and reduction is dis cussed in detail. Using the proposed methodology, 285 plausible detections are claimed and several are reviewed in detail. Keywords: resident space objects; matched filter; admissible region; geostationary orbit; binary hypothesis testing
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ItemA scalable hardware-in-the-Loop simulation for satellite constellations and other multi-agent networks(Georgia Institute of Technology, 2018-05-01) DeGraw, Christopher F.
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ItemCoulomb-Force Based Control Methods for an n-Spacecraft Reconfiguration Maneuver(Georgia Institute of Technology, 2018-05-01) Swenson, Jason C.In an electrically-charged space plasma environment, spacecraft Coulomb forces are shown as a potential propellant-free alternative for an n-spacecraft formation reconfiguration maneu ver with nd deputy spacecraft. Two Coulomb force based methods (and one method without Coulomb forces) for reconfiguration maneuvers are developed, tested, and evaluated. Method 1a applies Direct Multiple Shooting in order to calculate the optimal thrust inputs of a min imum fuel trajectory. Method 1b uses the results from Method 1a to compare the optimal thrust input to the set of all possible resultant Coulomb force vectors at each point in time along a trajectory. Method 2, formulated from optimal control theory, solves directly for nd spacecraft charge states at each point in time with Clohessy-Wiltshire relative dynamics and minimizes the final relative state vector error. The overall performance of Method 2 is shown to be superior than that of Method 1b in terms of both relative state vector error and total computational time. Furthermore, Method 2 shows performance comparable to the optimal minimum fuel trajectory calculated in Method 1a.
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ItemEarly Collision and Fragmentation Detection of Space Objects without Orbit Determination(Georgia Institute of Technology, 2018-05-01) Axon, Lyndy E.This paper demonstrates that from using the hypothesized constraint of the admissible regions it is possible to determine if a combination of new uncorrelated debris objects have a common origin that also intersects with a known catalog object orbit, thus indicating a collision or fragmentation has occurred. Admissible region methods are used to bound the feasible orbit solutions of multiple observations using constraints on energy and radius of periapsis, propagating them to a common epoch in the past, and using sequential quadratic programming optimization to find a set of solution states that minimize the Euclidean distance between the observations at that time. If this given this set of solutions intersects with a catalog object orbit, then that object is the probabilistic source of the debris objects. This proposed method is demonstrated on an example of a low-earth object observation.
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ItemStrategic Planning of Abort Trajectories for Manned Lunar Missions(Georgia Institute of Technology, 2018-05-01) Yuricich, JillianA resurgence in manned lunar missions is on the horizon with private space companies and nation states alike competing to be the first to return to the Moon since the Apollo program ended in 1972. Technology and mission planning abilities have expanded im mensely in the almost half century of time that has elapsed since Apollo 11 first landed on the Moon. It is therefore necessary to evaluate and update how abort procedures should be strategized given the increase in volume of crewed missions planned for the Moon and beyond. This research seeks to investigate three abort strategies for space vehicles in or bit around the Moon and provide a high-level road map of options based on their fuel costs and time of flight to return to the Earth. By investigating previous historic works in combination with more recent research, this paper intends to capitalize on previous math ematical derivations and combine multiple abort strategies into a coherent simulation tool. It is expected that given the nominal trajectory of a circular lunar orbit, a specific abort strategy with options ranging from single to triple-impulse requirements can be selected as the optimal trajectory for a return to Earth. This research provides a high-level road map of contingency plans and fills a gap in understanding abort strategies from lunar orbit.
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ItemAlgorithmic Insufficiency of RSSI Based UKF for RFID Localization Deployment On-Board the ISS(Georgia Institute of Technology, 2018-05-01) Carnes, Joshua T.This work evaluates the application of Unscented Kalman Filter (UKF) to generate stochastic localizations of radio frequency identification (RFID) chips in a sensor poor, highly reflective environment. Localization is done through the application of kNN algorithms and UKF methods to assign to reference RFID tags. The research is conducted in response to the needs of NASA for an application on the International Space Station. While the UKF has been shown to be effective on RFID streams, the sensor poor environment and difficult conditions aboard the ISS cause a loss of localization. This work shows that a UKF alone is insufficient for deployment on the ISS and proposes an alternative. Validation methods are proposed, and initial results are generated. Current industry methods are explored as benchmarks for algorithm performance.
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ItemAnalysis of an Aerotorquer for the Control of CubeSats with Large Torque Requirements(Georgia Institute of Technology, 2018-04-27) Heron, Matthew R.Traditionally, Earth-pointing CubeSats have Attitude Control Systems (ACS) that consist of two primary types of actuators – reaction wheels and magnetorquers. Reaction wheels provide the fine attitude control while the magnetorquers prevent reaction wheel saturation. This control scheme may not always meet CubeSat mission requirements, however, for some missions require a spacecraft with a large angular momentum (e.g. CubeSats with spinning instruments). In this case, the gyroscopic stiffness induced by the angular momentum will impose large torque requirements on the ACS to maintain Earth-pointing. This torque requirement on the reaction wheels may cause the wheels to spin up to saturation before the magnetorquers can unload the reaction wheel momenta. This paper analyzes the ACS feasibility and design of a 12U dual-spinning, nadir-pointing satellite. Two distinct ACS schemes are considered. In the first control scheme, the embedded angular momentum of the satellite is offset by a momentum wheel. In the second scheme, the use of an aerotorquer (i.e. drag panel) to provide the required torque is considered.
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ItemA Statistical Analysis and Predictive Modeling of Safing Events for Interplanetary Spacecraft(Georgia Institute of Technology, 2018-04-27) Pujari, Swapnil R.Unexpected spacecraft failures and anomalies may prompt autonomous on-board systems to change a spacecraft’s state to a ‘safe mode’ in order to isolate and resolve the problem. Future interplanetary missions such as Psyche and the proposed Next Mars Orbiter mission concept, plan to use solar electric propulsion on-board. Continuous operation of the thrusters is necessary in order to achieve their mission objectives. The mo tivation for this paper stems from a need to better predict safing events based on various mission factors such as mission class, destination, duration, etc. Modeling spacecraft inoperability due to a spacecraft entering safe mode is imperative in order to appropriately allocate spacecraft margins and shape design & operations requirements. This paper contributes to the area of safing events by further analyzing trends and dependencies within the available data subsets, and develops predictive models of frequency and recovery times of safing events for interplane tary spacecraft missions. First, the full safing event dataset is split into multiple subsets based on various mission classifiers. By employing the Chi Squared hypothesis test, the degree of dependency between classifiers is assessed. A parametric analysis is conducted using a single and mixture of two Weibull distributions. The optimal parameters that would best fit the full dataset and subsets are computed by a maximization likelihood algorithm. The mean square error and Akaike Information Criteria represent goodness-of-fit criteria for the computed distributions; insight into any inherent bi-modal behavior is identified through these criteria. A supervised learning algorithm is utilized in captur ing and understanding relationships between input and output variables, and utilizing these to predict unknown outcomes. For the safing event database, two Gaussian process models are trained, tested, and deployed: one for time-between-events and the other for recovery durations. By incorporating these Gaussian Process models into a mission simulation framework, a Monte Carlo simulation of the likelihood of inoperability rates is conducted to robustly predict safing events. A greater understanding of the safing event dataset through statistical & parametric analyses, and the development of a Gaussian Process model for predictions enables interplanetary mission planners to make more informed decisions during spacecraft development