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Master's Projects

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search.filters.applied.f.advisor: Lightsey, E. Glenn × End date: 2019 × Start date: 2019 × Item Type: Publication × Has files: Yes ×

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The Design, Assembly, and Testing of Magnetorquers for a 1U CubeSat Mission

2019-12-12 , Amin, John

Over the next few years Georgia Tech’s Space System Design Lab (SSDL) will design and develop several 1U CubeSat missions starting with GT-1. These missions will include an Attitude Determination and Control Systems (ADCS) utilizing torque rods to control detumble and orbital attitude. This paper describes the design and construction and testing of GT-1’s torque rods and will serve as a resource to help guide future torque rod iterations. The first section details the equations and mathematics behind torque rods. Next, the design section considers factors influencing the magnetic dipole moment including core material, part length, and radius. It then describes the manufacturing and assembly process of torque rods involving core shaping and layer winding. It then describes the test setup to test the torque rod’s magnetic dipole moment and later indicates topics of future work.

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Closing the Power Budget Architecture for a 1U CubeSat Framework

2019-05-01 , Tadanki, Anirudh

A 1U CubeSat framework is designed as a baseline for future missions at Georgia Tech’s Space Systems Design Laboratory. The goal of the initial CubeSat is primarily educational, and future iterations intend to demonstrate a low cost and repeatable life-cycle process that overcomes the high turnover of labor faced by most universities. The purpose of the initial CubeSat design is to return detailed ADCS data from the reaction wheel, magnetorquers, and GPS on board. Due to the volume constraints of a 1U form factor, the presented power budget features various power profiles aimed to maximize the lifetime of the CubeSat from a deployment in an orbit similar to the ISS. From this, pointing requirements for the ADCS system can be derived to maximize solar panel exposure to sunlight, and future 1U CubeSats have a better understanding of the tight margins present in the design.

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X-Ray Pulsar Navigation Instrument Performance and Scale Analysis

2019-12-01 , Payne, Jacob Hurrell

This thesis investigates instruments for autonomous satellite navigation using measurements of X-ray emissions from millisecond pulsars. A manifestation of an instrument for this purpose, called the Neutron star Interior Composition Explorer (NICER), was launched to the International Space Station in 2017. The NICER instrument was designed to observe X-ray emissions from neutron stars for astrophysics research, and is out of scale in terms of volume, power consumption, mass and mechanical complexity to be useful for small satellite missions. This work surveys the range of existing X-ray observation missions to tabulate collecting areas, focal lengths, and optical configurations from milestone missions which describe the evolution of the state of the art in X-ray observatories. A navigation demonstration experiment, called the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT), was conducted using the NICER instrument. The experimental performance observed from NICER through the SEXTANT navigation demonstration is compared to theoretical predictions established by existing formulations. It is concluded that SEXTANT benefits from soft band (0.3-4 keV) exposure to achieve better accuracy than predicted by theoretical lower bounds. Additionally, investigation is presented on the readiness of a navigation instrument for small satellites using compound refractive lensing (CRL) and derived designs. X-ray refraction achieves a much shorter focal length than grazing incidence optics at the expense of signal attenuation in the lens material. Performance estimates and previous experimental results are presented as a baseline for physical prototypes and ix hardware testing to support future development of a physical instrument. The technological hurdle that will enable this tool is manufacturing precise lenses on a 3- micron scale from materials like beryllium with low atomic mass. Recent X-ray concentrator concepts demonstrate progress towards an implementation that can support a CubeSat scale navigation instrument optimized for soft band (0.3-4 keV) X-rays

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Development of Maneuverable Deep Space Small Satellites

2019-05-01 , Wilk, Matthew D.

Propulsion systems of some form are required for most CubeSat missions looking to venture beyond Low earth Orbit (LEO). The Lightsey Research Group has been producing additively manufactured satellite thrusters for various missions since 2012 and is experi enced in their designing, manufacturing, testing, and operation of such systems. These thrusters traditionally have been printed using stereolithography (SLA) methods, but new metal printing techniques allow for the use of traditional aerospace aluminum alloys. Metal printing of thrusters allows for the combining of satellite structure with propulsion system piping and tanks contained within the satellite. This research examines the design process for a 1U additively manufactured satellite with propulsion designed into the structure, the design and simulation of a new feedback control scheme for angular momentum manage ment, and documents the efforts made towards radiation tolerant electronics. The sum of works contained within are towards the common goal of enabling more beyond LEO CubeSats.

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Mahalanobis Shell Sampling (MSS) method for collision probability computation

2019-12-01 , Núñez Garzón, Ulises E.

Motivated by desire for collision avoidance in spacecraft formations, and by the need for accurately computing low kinematic probabilities of collision (KPC) in spacecraft collision risk analysis, this work introduces an algorithm for sampling from non-degenerate, multidi mensional normal random variables. In this algorithm, the analytical relationship between certain probability density integrals of such random variables and the chi-square distribution is leveraged in order to provide weights to sample points. In so doing, this algorithm allows direct sampling from probability density “tails” without unduly penalizing sample size, as would occur with Monte Carlo-based methods. The primary motivation for the development of this algorithm is to help in the efficient computation of collision probability measures for relative dynamic systems. Performance of this method in approximating KPC waveforms is examined for a low-dimensionality dynamic example. However, this method could be applied to other dynamic systems and for probability density integrals other than collision probability measures, allowing for efficient computation of such integrals for problems where analytical results do not exist. Therefore, this method is suggested as an alternative to random sampling algorithms such as Monte Carlo methods or the Unscented Transform.

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