The space environment presents various challenges when designing systems and selecting materials for applications beyond Earth’s atmosphere. For mission success, these challenges must be considered. One of the detrimental aspects of the space en- vironment is Atomic Oxygen, AO. Only present in harmful quantities in Lower Earth Orbit, LEO, AO causes significant damage to materials by breaking molecular bonds. California Polytechnic State University’s, Cal Poly’s, space environments laboratory features an apparatus capable of simulating this environment. Very thin or short samples were tested to observe the mass loss due to erosion of the sample material. Recent modifications to the system allow it to expose surfaces of three dimensional objects to AO rather than only those two dimensional objects. Simulating this effect on taller samples makes available the opportunity to test coupons that are then used in additional testing to measure the effect of that erosion on other properties. Challenges in adapting the AO system are explored and addressed, as well as some possible use cases for future work. As a use case, bending moment specimens were exposed to AO prior to testing in four point bending. Multiple regression models were constructed to determine variables contributing to slope changes between specimen pairs’ linear-elastic regions of force-displacement graphs. Results show that AO exposed specimens had significantly gentler slopes in the linear elastic region of the force-displacement curve, meaning that AO exposure reduced structural rigidity of the coupons.

Space debris is a growing threat to operational satellites and satellite manufacturing organizations. Leaders in satellite manufacturing organizations lacking adequate knowledge on the space debris risks could be at a competitive disadvantage. The purpose of this explorative case study was to explore strategies leaders in satellite manufacturing organizations use to mitigate risks through the conceptual lens of stakeholder theory, contingency theory, and general system theory. The research questions addressed strategies to mitigate the debris threat from the perspectives of both ongoing concerns and long-term risk resolution. Data were collected via in-depth interviews with 12 leaders, purposively selected, in satellite manufacturing organizations, and supplemented with documentation from the literature and archival records from NASA. Member checking was used to validate the transcribed data subsequently coded into 6 themes that included: meeting requirements; using analytical techniques; using shielding to protect satellites; implementing material and process innovation; developing satellite services; and generating end of mission requirements. Recommendations include maintaining and developing analytical competencies, funding research and development, and establishing standardization. Using strategies that facilitate risk mitigation and the preservation of the space environment, business leaders could benefit by developing strategic road maps that ensure continued access to space. Implications for social change include contributing to social stability, technology advancement, increased knowledge base, economic growth, higher education, and improved standard of living.

Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this work is to improve yield measurements for insulator materials, which can be difficult to test using conventional methods due to charge accumulation in insulators.Most studies of electron yield use a steady current electron beam in a vacuum chamber to irradiate materials to be tested. By comparing the amount of current deposited in the material to the total incident current, the emitted current can be calculated. This works well for conductors; however, insulators charge up quickly, which either repel incident electrons or reattract emitted electrons producing erroneous yield measurements. This study improves on methods that use a pulsed electron beam to measure yield with small amounts of charge per pulse, as well as neutralization methods to dissipate stored charge between pulse measurements.The improvements to instrumentation and data analysis techniques are quantified to demonstrate their validity. These improvements will allow for continued studies on extreme insulator materials. Future studies will provide new understanding of interactions between electron radiation and materials, which will allow for better modeling of spacecraft charging and the development of materials that meet desired electron emission specifications.

The main cause of spacecraft failures is due to the harsh space environment; therefore, rigorous testing of materials used in modern spacecraft is imperative to ensure proper operation during the life span of the mission. Enhancing the capabilities of ground-based test facilities allows for more accurate measurements to be taken as it better simulates the environment to which spacecraft will be exposed. The range of temperature measurements has been significantly extended for an existing space environment simulation test chamber used in the study of electron emission, sample charging and discharge, electrostatic discharge and arcing, electron transport, and luminescence of spacecraft materials. This was accomplished by incorporating a new two-stage, closed-cycle helium cryostat, which has an extended sample temperature range from 450 K, with long-term controlled stability of -7Pa) that can simulate diverse space environments. These existing capabilities include controllable vacuum and ambient neutral gases conditions (< 10-7 to 10-1 Pa), electron fluxes (5 eV to 30 KeV monoenergetic, focused, pulsed sources ranging from 10-4 to 1010 nA-cm-2), ion fluxes (<0.1 to 5keV monoenergetic sources for inert and reactive gases with pulsing capabilities), and photon irradiation (numerous continuous and pulsed monochromatic and broadband IR/VIS/UV [0.5 to 7 eV] sources). The original sample mount accommodates one to four samples of 1 cm to 2.5 cm diameter in a low-temperature carousel, which allows rapid sample exchange and controlled exposure of the individual samples. Multiple additional sample mounts have been added to allow for standalone use for constant voltage measurements, radiation induced and conductivity tests, as well as extended capabilities for electron-induced luminescent measurements to be conducted using various material sample thickness in the original existing space environment simulation test chamber.

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The research presented provides an overview of a 1U+ form factor propulsion system design developed for the Cal Poly CubeSat Laboratory (CPCL). This design utilizes a Radiofrequency Electrothermal Thruster (RFET) called Pocket Rocket that can generate 9.30 m/s of delta-V with argon, and 20.2 ± 3 m/s of delta-V with xenon. Due to the demand for advanced mission capabilities in the CubeSat form factor, a need for micro-propulsion systems that can generate between 1 – 1500 m/s of delta-V are necessary. By 2019, Pocket Rocket had been developed to a Technology Readiness Level (TRL) of 5 and ground tested in a 1U CubeSat form factor that incorporated propellant storage, pressure regulation, RF power and thruster control, as well as two Pocket Rocket thrusters under vacuum, and showcased a thrust of 2.4 mN at a required 10 Wdc of power with Argon propellant. The design focused on ground testing of the thruster and did not incorporate all necessary components for operation of the thruster. Therefore in 2020, a 1U+ Propulsion Module that incorporates Pocket Rocket, the RF amplification PCB, a propellant tank, propellant regulation and delivery, as well as a DC-RF conversion with a PIB, that are all attached to a 2U customer CubeSat for a 3U+ overall form factor. This design was created to increase the TRL level of Pocket Rocket from 5 to 8 by demonstrating drag compensation in a 400 km orbit with a delta-V of 20 ± 3 m/s in the flight configuration. The 1U+ Propulsion Module design included interface and requirements definition, assembly instructions, Concept of Operations (ConOps), as well as structural and thermal analysis of the system. The 1U+ design enhances the capabilities of Pocket Rocket in a 1U+ form factor propulsion system and increases future mission capabilities as well as propulsion system heritage for the CPCL.

An LED-based solar simulator has been designed, constructed, and qualified under ASTM standards for use in the Cal Poly Space Environments Laboratory. The availability of this simulator will enhance the capability of undergraduate students to evaluate solar cell and thermal coating performance, and offers further research opportunities. The requirements of ASTM E927-19 for solar simulators intended for photovoltaic cell testing were used primarily, supplemented by information from ASTM E491-73 for solar simulators intended for spacecraft thermal vacuum testing. Three main criteria were identified as design goals - spectral match ratio, spatial non-uniformity, and temporal instability. An electrical design for an LED-based simulator to satisfy these criteria was developed and implemented, making use of existing lab equipment where possible to minimize cost. The resulting simulator meets the desired spatial non-uniformity and temporal instability requirements of ASTM E927-19, but falls short of the spectral match ratio needed. This is shown to be due to a calibration issue that is easily amended via software. The simulator is overall Class UCB under ASTM E927, and Class CCC under ASTM E491. The simulator was used to conduct the same laboratory procedure for solar cell I-V curve testing as performed by undergraduate students, showing excellent promise as a course enhancement.

The concept of using the vibration transmitted through the structure of space systems whilst they are in flight for monitoring purposes is proposed and analysed.The performed patent review seems to indicate that this technique is not currently used despite being, in principle, a good way to obtain valuable knowledge about the spacecraft’s condition. Potential sources of vibration were listed and some of them were down-selected via a trade-off analysis for implementation in a numerical model of a CubeSat structure. Models were proposed for the sources chosen and implemented in the Ansys Workbench software, along with a simplified structure designed to be representative of a generic picosatellite mission.The results confirmed very different amplitude and frequency ranges for the sources of interest, which would make it difficult to monitor them with one type of sensor.Basic system requirements for accelerometer operating under space conditions were derived and commercial sources were identified as already having the technologies needed.The conclusion was a positive evaluation of the overall concept, although revising negatively the initial expectations for its performance due to the diversity encountered in the sources.

As the average temperature on Earth keeps rising and becoming a greater threat to life on Earth, several methods has been proposed to mitigate the effects of elevated temperatures or to lower the Earth's average temperature drastically. One suggestion is a solar sail shade that blocks a portion of the incoming sunlight. There are several difficulties to overcome for such a mission and a demonstrator has been proposed to show the feasibility of solar sail shading.This paper is a study of the space radiations interaction with solar sail membrane, in literature and with calculations of the radiation environment with the aim to investigate the feasibility of the demonstrator.The findings of this paper is that there is not enough to show that the mission will be successful, however it is feasible. The major difficulties are the temperature dependence and the still unknown reaction that thin material, the solar sail membrane, has with the space environment. The core interaction for a solar sail membrane is of an energy level range that has not been relevant in other fields, protons with energy less than 10 keV specifically, thus there is a lack of knowledge in the desired energy range. / Med Jordens ökande medeltemperatur har flera nationer på Jorden presenterat metoder för att reducera medeltemperaturen.Ett förslag är att skicka flera solsegel mellan Jorden och Solen för att blockera en del av det inkommande ljuset. Det finns flera utmaningar med detta förslag. För att undersöka om solsegel är en möjlig lösning så har en så kallad ”demonstrator” skapats. Syftet med ”demonstratorn” är att undersöka om lösningen är genomförbar.För att undersöka huruvida det är möjligt att fullgöra ”demonstratorns” uppdrag har rymdstrålningens interaktion med solseglets membran undersökts med hjälp av litteratur samt beräkningar.Slutsatsen är att det behövs mer information för att visa huruvida "demonstratorn" kommer klara det tänkta uppdraget. Den samlade informationen tyder än så länge på att uppdraget går att genomföra. Bland de större svårigheterna finns dels temperaturberoendet på väte-reaktionerna dels att reaktionen mellan solsegel och rymdstrålningen fortfarande är relativt okänd. Den aktuella interaktionen på solseglet ligger inom ett intervall av energinivåer som tidigare inte varit relevanta att undersöka. Detta gäller exempelvis protoner med energinivåer som understiger 10 keV. Därför saknas idag kunskap effekterna på solseglet inom de aktuella energinivåerna.

This dissertation discusses two aspects of computational fluid dynamics: high order spatial accuracy and convergence-rate acceleration through system preconditioning. Concerning high-order accuracy, the computational qualities of various spatial methods for the finite-volume solution of the Euler equations are presented. The two-dimensional essentially non-oscillatory (ENO), k-exact, and dimensionally split ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy and computational cost. Standard variable extrapolation methods are included for completeness. Inherent steady-state convergence difficulties are demonstrated for adaptive-stencil algorithms. Methods for reconstruction error analysis are presented and an exact solution to the heat equation is used as an example. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock-reflection problem. A vortex-shock interaction demonstrates the ability of the EN 0 scheme to excel in capturing unsteady high-frequency flow physics. Concerning convergence-rate acceleration, characteristic-wave preconditioning is extended to include generalized finite-rate chemistry with non-equilibrium thermodynamics Additionally, the proper preconditioning for the one-dimensional Navier-Stokes equations is presented. Eigenvalue stiffness is resolved and convergencerate acceleration is demonstrated over the entire Mach-number range from the incompressible to the hypersonic. Specific benefits are realized at low and transonic flow speeds. The extended preconditioning matrix accounts for thermal and chemical non-equilibrium and its implementation is explained for both explicit and implicit time marching. The effects of high-order spatial accuracy and various flux splittings are investigated. Numerical analysis reveals the possible theoretical improvements from using preconditioning at all Mach numbers. Numerical results confirm the expectations from the analysis. The preconditioning matrix is applied with dual time stepping to obtain arbitrarily high-order accurate temporal solutions within an implicit formulation. Representative test cases include flows with previously troublesome embedded high-condition-number regions. / Ph. D.