The Alabama Experiment on Galactic-Ray In-Situ Shielding (AEGIS) Project

Alabama Experiment on Galactic-ray In-situ Shielding (AEGIS) is a 6U CubeSat to characterize the effect of deep space radiation environments on lunar regolith-based shielding while providing a workforce development platform under a statewide coalition of universities. In 2018, the Alabama Space Grant Consortium (ASGC) initiated the workforce development program to teach students from multiple engineering disciplines the rigors and requirements of spacecraft design. AEGIS is the flagship mission of this program, conducted by five universities across the state. As an educational program, the project is led and developed entirely by students with the support of faculty, industry, and NASA mentors. The unique approach of AEGIS as a university-based collaboration offers both research and education opportunities, opening the door for future partnerships and missions with increasingly ambitious goals and science deliverables. AEGIS has applied to be manifested aboard the Artemis2 launch vehicle under the CubeSat Launch Initiative. This presentation provides an overview of the science mission and its objectives, the project organization and management approach, and the spacecraft design

An Overview of the Alabama Burst Energetics eXplorer (ABEX) Mission

The Alabama Burst Energetics eXplorer (ABEX) project is a 12U scientific and educational mission to investigate Gamma-Ray Bursts (GRB) through spectral analysis and localization of joint gravitational-wave GRB mergers using wavefront timing analysis. The project is in development by a multi-university collaboration across Alabama with design work conducted by students under faculty advisement. The effort is organized and funded by the Alabama Space Grant Consortium and includes the University of Alabama, University of Alabama in Birmingham, University of South Alabama, Auburn University, and the University of Alabama in Huntsville. ABEX will deploy on a super-synchronous orbit and propulsively maneuver to a high eccentricity orbit of 300 km perigee by 60,000 km apogee at 27° inclination. From this high apogee destination, ABEX will observe GRB events using a suite of detectors that measure a broad energy range from keV to MeV. The highly eccentric orbit allows ABEX to perform wavefront timing between LEO gamma-ray missions as it passes through apogee. ABEX has several engineering systems being developed by cohort universities as part of its educational mission, specifically the On-Board Computers, Electrical Power System, Flight Software, chassis, and instrumentation. In this paper we present a broad overview of the mission, including the scientific and educational goals, spacecraft design, instrument design, and operations concept

A model-based systems engineering approach to space mission education of a geographically disperse student workforce

The Alabama Burst Energetics eXplorer (ABEX) is a 12U CubeSat commissioned by the Alabama Space Grant Consortium; its astrophysics mission is to study the low energy, prompt emission of Gamma-ray Bursts in both gamma and X-ray spectra. The ABEX program is unique in that its workforce is comprised of individuals at seven colleges and universities around the state of Alabama. ABEX management releases Requests for Proposals (RFP) for Senior Design (SD) projects or university research groups to design and build spacecraft subsystems; university faculty with experience and facilities for the development of that subsystem respond to the RFPs to create a team. ABEX supports undergraduate SD students, graduate student mentors, and faculty technical advisors for all spacecraft subsystems in both ground and flight mission segments. Each team has between 5-15 undergraduate students, meaning ABEX teaches spacecraft design to ~85 undergraduate students at any given time; ABEX may be the largest collegiate CubeSat program in the world. The undergraduate labor force turns over, or cycles to new students, every 4-8 months, so ABEX can teach hands-on spacecraft design to over 100 students every year and has taught over 200 to date. Two features of ABEX create a difficult Systems Engineering (SE) environment: the undergraduate labor force turnover rate and the geographically disperse workforce. Most subsystem teams exist within two-semester SD courses, but some teams, like Flight Software, only exist for one semester before the undergraduate team turns over. This means the student onboarding process must be efficient and the material hand-off process effective if any substantive contribution to the spacecraft is to be made in their brief course period. A Model-Based Systems Engineering (MBSE) Integrated System Model (ISM) was created using SysML as a full-program organization of mission requirements, subsystem architectures, verification and validation procedures, and team interaction tracking methodologies for workforce turnover effect mitigation with ISM-exported artifacts as central objects of stage-gate reviews. An ABEX website was created with processes for first-time student onboarding, ISM artifact dissemination, and intercollegiate document transfer in addition to being a public relations arm for the program. With education at the forefront of ABEX, educational requirements and performance measures detailing onboarding efficiency, workforce preparedness, and alumni vocation results are defined within the ISM and used to evaluate program education proficiency. Program organization, ISM structure, and spacecraft design is presented with an emphasis on quantifying student education as a result of program involvemen

Host susceptibility hypothesis for shell disease in American lobsters

Author Posting. © American Fisheries Society, 2007. This article is posted here by permission of American Fisheries Society for personal use, not for redistribution. The definitive version was published in Journal of Aquatic Animal Health 19 (2007): 215-225, doi:10.1577/H06-014.1.Epizootic shell disease (ESD) in American lobsters Homarus americanus is the bacterial degradation of the carapace resulting in extensive irregular, deep erosions. The disease is having a major impact on the health and mortality of some American lobster populations, and its effects are being transferred to the economics of the fishery. While the onset and progression of ESD in American lobsters is undoubtedly multifactorial, there is little understanding of the direct causality of this disease. The host susceptibility hypothesis developed here states that although numerous environmental and pathological factors may vary around a lobster, it is eventually the lobster's internal state that is permissive to or shields it from the final onset of the diseased state. To support the host susceptibility hypothesis, we conceptualized a model of shell disease onset and severity to allow further research on shell disease to progress from a structured model. The model states that shell disease onset will occur when the net cuticle degradation (bacterial degradation, decrease of host immune response to bacteria, natural wear, and resorption) is greater than the net deposition (growth, maintenance, and inflammatory response) of the shell. Furthermore, lesion severity depends on the extent to which cuticle degradation exceeds deposition. This model is consistent with natural observations of shell disease in American lobster

The Near-Earth Space Radiation Environment During Solar Cycle 25: Consequences for the Alabama Burst Energetics eXplorer

The Alabama Burst Energetics eXplorer (ABEX) is a 12U mission to enhance the detection of low energy Gamma Ray Burst (GRB) components and provide improved, rapid localization of short GRBs for multiwavelength follow up via GRB measurements outside the Van Allen Belts (VAB). The ABEX launch date is Q4 2024 during the peak of solar cycle 25; the ABEX science orbit is 300 km perigee by 60,000 km apogee with an inclination of 27°. This orbit defines distinct radiation environments in Low Earth Orbit, crossing the VABs, performing science operations outside the VABs, and Coronal Mass Ejection (CME) conditions. Numerical trajectory data was generated in AGI’s Systems Tool Kit and provided to the Space Environment Information System (SPENVIS). VAB trapped particle, Solar Energetic Particle, and Galactic Cosmic Ray particle fluxes were determined for the ABEX orbit. Empirical fits for Total Ionizing Dose are provided per particle source. Solar cell degradation as a function of Non-Ionizing Energy Loss was calculated per coverglass thickness with mass implications. Charged Particle Heating is characterized in a full thermal radiation model. Single Event Effects and surface charging are not discussed in the context of particle flux

An Estimated Contribution of Glacier Runoff to Mongolia’s Upper Khovd River Basin in the Altai Mountains

In the semiarid climate of northwestern Mongolia, glaciers are critical contributors to water resources, particularly during the dry summer months. Nevertheless, our knowledge of the contribution of glacier runoff in the Upper Khovd River Basin (UKRB) is limited. This study investigates the impact of glacier recession on the UKRB\u27s hydrology in western Mongolia\u27s Altai Mountains. The analysis included glaciological method measurements, satellite-derived glacier extent records, and a simple ice ablation model. Our modeling used a mass balance gradient of 0.50 meters water equivalent 100 m–1 for the years 2000, 2010, and 2016 and included a sensitivity analysis that applied lower and upper mass balance gradient values and ±200 m around the equilibrium line altitude (ELA). The glacier contribution to the UKRB\u27s water resources decreased from almost 8% in 2000 to 6.7% in 2016. Hypsometries revealed that glacier areas decreased at all elevations, indicating that only small accumulation zones exist. Therefore, applying a modeled increased ELA better represents glacier contribution to total runoff, at 18.7% in 2000 and 15.4% in 2016. The decreasing glacier runoff contribution indicates that the UKRB glaciers have passed the tipping point of an increased contribution that first follows enhanced melting. The continued glacier recession and uncertain water availability represent challenges for water resource management and future human–water relations in the Mongolian Altai

Model-Based Systems Engineering and F’: Proof of Concept Via the Creation of an On-Orbit Textual Command Parsing Component for the ABEX Mission

The Alabama Burst Energetics eXplorer (ABEX) mission is defining spacecraft architecture, behavior, mission phases, operational states, risks, and requirements in a Model-Based Systems Engineering (MBSE) Integrated Systems Model (ISM) using SysML in Cameo Enterprise Architecture (CEA). The satellite structural design can be exported from CEA as Extensible Markup Language (XML) specifications and imported to F’, an open-source Flight Software (FSW) framework from NASA’s Jet Propulsion Laboratory. F’ contains background components intended to be connected to user-defined components in the XML after it is exported from the ISM; in this work, ABEX is representing F’ background components in SysML Internal Block Diagrams from which the XML is generated. As a proof of concept for this MBSE-centric FSW implementation, the ABEX FSW team has created a Command Reader component from MBSE-generated XML and tested command enaction on a Raspberry Pi breadboard system for three test cases representing on-orbit command triggers

Hyperentangled States

We investigate a new class of entangled states, which we call 'hyperentangled',that have EPR correlations identical to those in the vacuum state of a relativistic quantum field. We show that whenever hyperentangled states exist in any quantum theory, they are dense in its state space. We also give prescriptions for constructing hyperentangled states that involve an arbitrarily large collection of systems.Comment: 23 pages, LaTeX, Submitted to Physical Review

High-Fidelity Spacecraft Thermal Modeling: Synthesis of STK, SPENVIS, MATLAB, Simulink, and Thermal Desktop using Model-Based Systems Engineering

Verification and Validation (V&V) by analysis for required spacecraft Heater Wattage (HW) and Radiator Area (RA) is a rigorous, iterative procedure highly dependent on spacecraft areas, surface absorptivity, surface emissivity, orbital position, orbital attitude, and operational heat generation. The Alabama Burst Energetics eXplorer (ABEX) mission adopts a Model-Based Systems Engineering (MBSE) approach to analysis wherein model strengths and weaknesses are considered synergistically and integrated using SysML parametric and structural diagrams to create a System of Models (SoM). In this work, a procedure for comprehensive spacecraft thermal modeling is detailed using MBSE-centric Modeling and Simulation (M&S) practices. The SysML model is used as a foundational data source for all other models, and non-SysML model exports are provided back to the SysML model in useful format. Because the analytical models in Systems Tool Kit (STK), MATLAB, Simulink, Thermal Desktop, and the Space Environment Information System (SPENVIS) are sourcing input data only from the SysML model, V&V for input data pedigree is only required in SysML for the purposes of National Aeronautics and Space Administration (NASA)-STD-7009: Standard for Models & Simulations, saving valuable program schedule time. Common of many thermal analysis approaches, a low-fidelity, isothermal model is first developed in MATLAB to provide environmental calculations and preliminary HW and RA values to a higher-fidelity model, here developed in Simulink. The non-isothermal Simulink model results inform a Thermal Desktop model, which is used as the basis for qualification-level hardware development. In the analytical models, STK simulates spacecraft modes of operation and communication profiles to export transient spacecraft position and velocity state vectors, solar position state vectors, Earth position state vectors, and unit vectors orthogonal to each spacecraft face, among non-thermal data. An orbital model in SPENVIS produces corpuscular radiation integral flux data for the determination of Charged Particle Heating (CPH), and the MATLAB model imports the STK and SPENVIS data. In MATLAB, heat fluxes from direct solar emission, Earth emission, Earth albedo, CPH, and Free Molecular Heating (FMH) are calculated and converted to absorbed heat values; radiation surface reflectivity is calculated using specular, spectral Fresnel relationships accounting for complex, spectral refractive indices of both the spacecraft surface coating material and base layer material, surface coating material thickness, and radiation Angle of Incidence (AOI). The MATLAB model utilizes an isothermal energy balance to output a low-fidelity HW and RA value required to stay above and below component operational temperatures, respectively. In Simulink, component thermal capacitances are distributed in a thermal resistance network with each discrete spacecraft component considered isothermal; absorbed heat and advanced reflectivity calculations are also recalculated per component. An array of values is generated for both HW and RA between zero and twice the value provided by the MATLAB isothermal model to create a matrix of potential HW and RA combinations. The Simulink model determines an operational envelope of viable HW and RA combinations for user-defined heater and radiator locations; acceptable HW and RA combinations are those that result in component temperatures within operational boundaries. The HW and RA combinations at the edges of the Simulink-derived operational envelope are provided to a three-dimensional, geometry-specific Thermal Desktop model wherein high-fidelity HW and RA values can be analyzed specific to mounting considerations. In this SoM progression from MATLAB to Simulink to Thermal Desktop driven by data inputs from STK and SPENVIS with a central source of truth for all models based in SysML, uncertainty and risk regarding thermal control analysis results are systematically mitigated