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Daniel Guggenheim School of Aerospace Engineering
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ItemDesign of the VISORS and SWARM-EX Propulsion Systems(Georgia Institute of Technology, 2022-12-01) Hart, Samuel T. ; Lightsey, E. GlennThe Georgia Tech (GT) Space Systems Design Lab (SSDL) will deliver 3-D printed cold gas propulsion systems for the VISORS and SWARM-EX CubeSat formation flying missions. This report provides an overview of the working principle of these and past propulsion systems designed by the SSDL. Further information is provided about the specific designs of each of these systems and the problems encountered throughout the design process. Additionally, recommendations for improvements to future designs are outlined. An analysis of the effects of temperature on these systems is also presented.
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ItemBest Practices and Considerations for Planning and Conducting Integration of University CubeSats(Georgia Institute of Technology, 2022-12-01) Rawson, WilliamThis paper seeks to serve as a resource for students entering the integration phase of a CubeSat project by compiling best practices and practical considerations from several projects in the Space Systems Design Lab at the Georgia Institute of Technology. The integration phase can be a particular challenge for university CubeSat programs given the value of practical experience in performing these activities and the challenge of managing a student workforce with constant turnover. The topics covered include best practices for planning the integration phase of a project, considerations when performing integration activities, and the characteristics of good assembly procedures. Although the focus is on spacecraft-level integration of CubeSats in a university setting, many of the considerations are applicable outside the academic setting and to subsystem-level integration activities as well. Finally, a case study will be presented illustrating the planning of integration activities for the VISORS mission, a two 6U CubeSat formation-flying mission
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ItemNumerical Optimization of Satellite Avoidance Maneuvers(Georgia Institute of Technology, 2022-12-01) Sheikh, FirasThis paper investigates the numerical optimization of a collision avoidance maneuver and phase return for a satellite in a constellation network. The time until collision and return time are varied, and three impulse maneuvers are assumed. The total Delta-V is minimized while avoiding the collision by 1 km or greater and returning to the original satellite orbit phase. For this analysis, the Clohessy-Wiltshire (CW) solutions were utilized to linearize the system of equations for relative orbital motion without perturbation assumptions. Results demonstrated that a greater time until collision generally produces minimized Delta-V options but longer total maneuver times as a tradeoff.
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ItemCrater Projection in Linear Pushbroom Camera Images(Georgia Institute of Technology, 2022-10) Mancini, Michela ; DeVries, Carl ; Thrasher, Ava C. ; Christian, John A.Science images of the Moon and Mars are often captured with pushbroom cameras. Craters with elliptical rims are common objects of interest within the the images produced by such sensors. This work provides a framework to analyze the appearance of crater rims in pushbroom images. With knowledge of only common ellipse parameters describing the crater rim, explicit formulations are developed and shown to be convenient for drawing the apparent crater in pushbroom images. Implicit forms are also developed and indicate the orbital conditions under which craters form conics in images. Several numerical examples are provided which demonstrate how different ellipse formulations can be interpreted and used in practice.
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ItemLOST in Space: Optimal Triangulation for Celestial Localization(Georgia Institute of Technology, 2022-10) Henry, Sébastien ; Christian, John A.Optical measurements are a key part of modern interplanetary navigation. The statistically optimal Linear Optimal Sine Triangulation (LOST) algorithm is applied to the context of celestial navigation. In addition to optimal triangulation methods, celestial navigation requires the consideration or target ephemeris errors, light aberration, and light time-of-flight. In most cases, only light aberration and light time-of-flight change the expected direction of the measured line-of-sight (LOS). These effects are found to be non-negligible at typical observer velocities (for light aberration) and planet velocities (for light time-of-flight). The effects of the position uncertainty of planets are only important when the observer is close to them. The LOST framework provides a mechanism to conveniently consider all of these effects.
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ItemMethods for Navigation in the Nearby Interstellar Medium(Georgia Institute of Technology, 2022-09) Christian, John A.Recent years have seen an increased interest in sending dedicated spacecraft to explore the nearby interstellar medium (NISM). Such a mission would be instrumented to study the so-called heliosphere on the outskirts of our Solar System, where the solar wind and helopspheric magnetic field interact with interstellar environment (e.g., cosmic radiation). While the scientific value of such a mission is clear, the design and operation of a spacecraft to accomplish this mission is difficult. Indeed, due to the immense distances involved, navigation is expected to be amongst the most challenging tasks. This work explores a variety of navigation observables and frameworks that one might use to navigate a mission within the NISM. Detailed models are presented for all of the major sources of navigation information, including Earth-based radiometric tracking, visible-spectrum star sightings, X-ray pulsar navigation (XNAV), StarNAV, and others. The utility of these observables is then studied within an orbit determination framework, along with consideration of the quality of state knowledge most likely required to operate in the NISM. Issues related to time-keeping are also discussed. Numerical results are presented as a way to illustrate the efficacy of various approaches.
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ItemLine of Sight Observational and Inertial Sensing Requirements for Multi-UAV Tracking subject to GNSS Denial(Georgia Institute of Technology, 2022-08) Bouhall, Matthew M.
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ItemImpacts of Altitude on Expectation Maximization-based Data Association and Orbit Estimation(Georgia Institute of Technology, 2022-08) Sakson, Daniel
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ItemSystems 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. JudLunar 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.
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ItemGeometric Initial Orbit Determination From Bearing Measurements(Georgia Institute of Technology, 2022-08) Duff, Timothy ; Mancini, Michela ; Leykin, Anton ; Christian, John A.Initial orbit determination (IOD) from only bearing measurements is a classical problem in astrodynamics. The classical solutions of Gauss, Laplace, and others can solve this problem with three bearing measurements collected at known times. In this work, we apply concepts from algebraic geometry to investigate purely geometric solutions to this same problem. It is shown that five optical sightings at unknown times may be used to determine the orbit of an unknown spacecraft. The solution only requires knowledge that the spacecraft is following a conic orbit, with no need for any orbit propagation as part of the IOD process.