Browsing by Subject "CubeSat"

Now showing 1 - 5 of 5
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    Characterizing Performance and Errors of Coarse Sun Sensors
    (2017-12) Saborio, Ricardo J
    This presentation focuses on outlining the experimental setup and results for the characterization of Coarse Sun Sensor performance for in-orbit attitude determination in small satellites. Coarse Sun Sensors provide an inexpensive alternative to the more commonly used Fine Sun Sensors in the aerospace industry. These sensors are a fraction of the cost ($1.50 vs $3500 per unit) of the space grade sun sensors in regular satellites and, based on the results obtained in this work, the sensors themselves prove to be relatively effective at measuring the incoming sun vector. The work done in this Undergraduate Research Opportunity (UROP) is intended to serve as a stepping-stone for the development of an inexpensive sun-sensor packet for the University of Minnesota small satellite research group’s payloads. These payloads require accurate pointing at the sun while in orbit and thus such a sensor packet would be key to mission success.
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    Differential X-Ray and Gamma-Ray Positioning System for Nanosatellites
    (2015-12-27) DeLange, Josiah
    A CubeSat is a type of miniaturized satellite for space research. Utilization of a simplified infrastructure enables a low-cost platform to test the space readiness of new hardware without an exorbitant amount of prohibitive design. One of the areas where CubeSats offer promise is in the development of new satellite technology or scientific instruments for astronomical observations. We look at a CubeSat instrument which is able to pick up gamma ray bursts (GRBs) in the hard X-ray to gamma band. Implementation of this concept requires a precise characterization of incoming photons and thus requires energy detectors well suited for the energy range of interest, coupled with the most practical processing electronics. A compact CubeSat photon detector needs to be able to record fluxes with minimal dead time (time spent storing information). These fluxes make up signals which can be used to compute a position of the CubeSat relative to other CubeSats based on time difference of arrival (TDOA), similar to the operation of GNSS. Here we show the effects of signal noise on navigational accuracy, and show how a simple ripple counter circuit can improve the burst-to-background ratio of a photon-by-photon particle detector. The high-altitude ballooning team aims to push this technology forward and provide an updated template for CubeSat designs at the University of Minnesota.
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    Single-Vector Aiding of an IMU for CubeSat Attitude Determination
    (2020-07) Laughlin, Kail
    This thesis examines CubeSat attitude determination using the Earth’s magnetic field (EMF) vector aiding a low-cost IMU. CubeSats provide relatively cost-effective methods of performing scientific research in orbital environments. However, to adequately perform this research, knowledge of the CubeSat’s orientation in 3D space (attitude) is often required. To that end, the design of a reliable attitude determination (AD) system on-board a CubeSat is a critical aspect for many mission designers. As a primary goal of CubeSat design is to ensure science objectives are met while minimizing, cost, mass, and volume, this thesis investigates a minimal sensor approach to CubeSat AD. Specifically, an inertial based AD scheme reliant on the use of an inertial measurement unit (IMU) aided only by vector measurements of the Earth’s magnetic field (EMF) is developed. An extended Kalman filter (EKF) approach to recursively estimate the attitude on-orbit using an IMU and a three-axis magnetometer (TAM) is detailed. Additionally, we describe a test to assess the stochastic observability of the EKF developed. We present simulation results showcasing the performance of the AD system for multiple orbital inclinations and initial attitude errors. Moreover, we discuss conditions in which the EMF vector can and cannot be effectively utilized as the sole aiding measurement, and we evaluate the stochastic observability of the linearized discrete time system. We extend the AD system discussed here to two current University of Minnesota Small Satellite Research Lab CubeSat designs: IMPRESS and EXACT. We describe future work for the implementation of the AD system and potential improvements to the EKF design.
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    Studying Particle Acceleration in Solar Flares via Subsecond X-ray Spikes: Analysis and Instrumentation
    (2021-06) Knuth, Trevor
    Solar flares are explosive releases of magnetic energy in the solar atmosphere. Driven by a process known as magnetic reconnection, these events are associated with a wide array of interesting and dynamic phenomena. One such phenomenon is the acceleration of electrons to extremely high, nonthermal energies (10s-100s of keV). How these particles are accelerated is an outstanding question. Studying the X-ray radiation produced by these electrons is a direct means of studying the particles themselves. A potentially useful, yet rarely explored, feature in the solar flare X-ray flux is the existence of subsecond spikes of emission. In this dissertation I first provide a broad overview of the solar physics relevant to the study of particle acceleration and highlight the major past studies which focused on subsecond X-ray spikes. I then present the case study I performed in analyzing subsecond X-ray spikes in Fermi Gamma-ray Burst Monitor data. This study presents a comprehensive method of identifying, measuring, and analyzing these spikes. The results of this work help constrain the temporal characteristics of acceleration models as well as paving the way for future fast time domain analysis of solar flares using Fermi GBM data. I also discuss the work I have completed for the University of Minnesota Small Satellite Research Laboratory (UMNSSRL) developing fast time precision solar X-ray instruments. This included the founding of the UMN-SSRL itself, the creation of an analytical detector model for inorganic scintillators, and the development of the scientific requirements for multiple CubeSats. This work aims to progress the development of solar X-ray instrumentation capable of observing subsecond X-ray spikes.
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    Technologies to Solve the Orbital Debris Problem and its Effects on the Future of Space Exploration
    (2020-11) Allen, Nia
    This thesis deals with the orbital debris problem and its impact on small satellites such as CubeSats. Currently there is approximately eighteen tons of space junk that are currently in Earth orbit of which, 80% of this space debris is in Low Earth Orbit (LEO), which is where most spacecraft are launched into. A simplified orbital lifetime tool is developed and used to analyze the impact of the exponential rise in small satellite launches into LEO. It is shown that unless proactive measures are taken, the orbital debris problem will become worse in the future. To this end, two proactive approaches are examined: active removal of technologies and space policy changes. With respect to active removal technologies, three solutions being considered are examined: laser removal, electrodynamic tethers and mechanical nets. Laser removal involves using a space based or ground based laser to ablate material from space debris. The ablated material acts as a miniature thruster which decrease the semi-major axis of the debris’ orbit. The second technology considered is electromagnetic tethers. The tethers are based on using the earth's magnetic field to generate an electromotive force which acts as drag and, thus, causes the orbit of a debris object to decay. Lastly, there is the concept of a deployable net. A net with flexible rods is deployable from a host satellite and captures multiple forms of debris and knocks it out of orbit. For this concept, there is a closing mechanism to efficiently remove the debris. The advantages and disadvantages of all these technologies are analyzed.Next policy changes that can take advantage of these coming orbital debris removal technologies as well as existing technologies are considered. As well be shown, current space policies do not effectively deal with the orbital debris problem. Many papers have discussed how it is the launcher’s responsibility to remove their spacecraft from operational orbit. Since the creation of the Outer Space Treaty of 1967, countries know that space is deemed as an environment for exploration as opposed to property. After examining multiple scenarios involving various countries’ space interactions and removal technology proposals, it results into how orbital debris can be created. National space policies will be analyzed with focus on responsibility of removing orbital debris and keeping the space environment clean for future exploration. Another policy reform that is considered is that of future design standards. Using CubeSats as an example, we explore what kind of changes in design standards can help mitigate the orbital debris problem. To this end, typical CubeSat subsystems are separately examined, Structures, Propulsion, Control, Power, Navigation, and Communication. The analysis will also focus on how changes in the practice of designing these subsystems can be used to mitigate the orbital debris problem