Structural thermal optical performance (STOP) analysis and experimental verification of an hyperspectral imager for the HYPSO CubeSat

The evaluation of space optical instruments under thermo-elastic loads is a complex and multidisciplinary process that requires integrating thermal, structural, and optical disciplines. This thorough analysis often requires substantial resources, leading small satellite projects to exclude it from their schedules. However, even though the instrument discussed in this paper is compact, its complex design and stringent dimensional stability requirements demand a comprehensive evaluation of its performance under thermal loads. The hyperspectral camera, which comprises 18 lenses, a grating, a slit, and a detector, is especially vulnerable to thermo-elastic distortions, as the deformation of even a single lens could significantly impact its performance. In this paper, we present the experimental validation of the STOP analysis applied to the HYPerspectral Small satellite for ocean Observation (HYPSO) Hypespectral Imager (HSI) model. Both the HSI Structural Thermal Optical Performance (STOP) numerical model and the HSI engineering model were subjected to identical thermal conditions in the simulations and in a Thermal and Vacuum Chamber (TVAC), and subsequently the optical results derived from simulations and the test campaign compared. To characterize the thermal field, an infrared camera and thermocouples were used. Moreover, to assess the thermal performance of the HSI, we measured the Full Width at Half Maximum (FWHM) of the main peaks in the intensity-wavelength spectra when the hyperspectral camera targeted a known spectral lamp. After individually calibrating the STOP models so that the FWHM and index of the intensity peaks are in close alignment with the experimentally measured FWHM and index, the lenses most sensitive for displacements were characterizedMinisterio de Universidades | Ref. CAS21/00502Research Council of NorwayNorwegian Space AgencyEuropean Space AgencyUniversidade de Vigo/CISU

Estudo termo-elástico da plataforma de apuntamento para telescopios espaciais

The aerospace industry is experiencing a paradigm shift driven by cost reductions in launches and the standardization of platforms for small satellites. The primary motivation of this research is to address the technological gap in the pointing capabilities of small satellites, aiming to enhance the potential of these platforms. To achieve this, it is essential to consider all error sources, including thermo-elastic disturbances. Over the last two decades, the importance of thermo-elastic analyses has been increasing in the development of space programs. Recently, the European Guidelines for Thermo-Elastic Verification have been published, demonstrating the European Space Agency (ESA) interest in developing tools for accurately predicting these deformations, especially in applications with strict dimensional requirements. The thermo-elastic analysis methodology developed in this thesis is consistent with the approach adopted in the European guidelines. However, a different method is proposed to assess the degradation of optical performance parameters: the propagation of uncertainties throughout the analysis chain. This method allows for the standardization of language between thermal and structural analyses, as well as assessing which elements contribute to optical performance degradation and to what extent, breaking down the contribution to total uncertainty based on different parameters studied. This methodology was applied to the preliminary design of VINIS, an Earth observation space telescope developed by the Instituto de Astrofísica de Canarias (IAC). Thanks to the application of the uncertainty method for thermo-elastic evaluation of the instrument, two design elements affecting telescope operation were identified, which would not have been conclusively determined using traditional thermo-elastic analysis alone. It is important to note that not only space telescopes would benefit from the application of this methodology, but it could also be easily extended to any thermoelastic analysis of space instruments.La industria aeroespacial está experimentando un cambio de paradigma impulsado por la reducción de costes en los lanzamientos y la estandarización de plataformas para pequeños satélites. La principal motivación de esta investigación es abordar la brecha tecnológica en las capacidades de apuntamiento de los pequeños satélites, con el objetivo de mejorar el potencial de estas plataformas. Para lograrlo, es esencial considerar todas las fuentes de error, incluidas las perturbaciones termoelásticas. En las últimas dos décadas, la importancia de los análisis termo-elásticos ha ido en aumento en el desarrollo de programas espaciales. Recientemente, se han publicado las European Guidelines for Thermo-Elastic Verification, lo que demuestra el interés de la Agencia Espacial Europea (ESA) en el desarrollo de herramientas que permitan predecir con precisión estas deformaciones, especialmente en aplicaciones con requisitos dimensionales estrictos. La metodología de análisis termo-elástico desarrollada en esta tesis está en consonancia con el enfoque adoptado en las directrices europeas. Sin embargo, se propone un método diferente para evaluar la degradación de los parámetros de rendimiento óptico: la propagación de incertidumbres a lo largo de la cadena de análisis. Este método permite homogeneizar el lenguaje entre los análisis térmico y estructural, así como evaluar cuáles son los elementos que contribuyen a la degradación del rendimiento óptico, y en qué medida, desglosando la contribución a la incertidumbre total en función de los diferentes parámetros estudiados. Esta metodología se aplicó al diseño preliminar de VINIS, un telescopio espacial de observación terrestre que se está desarrollando por el Instituto de Astrofísica de Canarias (IAC). Gracias a la aplicación del método de incertidumbres para la evaluación termo-elástica del instrumento, se identificaron dos elementos de diseño que afectan la operación del telescopio y que no habría sido posible determinar de manera concluyente solo con el análisis termo-elástico tradicional. Es importante destacar que no solo los telescopios espaciales se beneficiarían de la aplicación de esta metodología, sino que sería fácilmente extensible a cualquier análisis termo-elástico de instrumentos espaciales

Optimization of the conceptual design of a multistage rocket launcher

The design of a vehicle launch comprises many factors, including the optimization of the climb path and the distribution of the mass in stages. The optimization process has been addressed historically from different points of view, using proprietary software solutions to obtain an ideal mass distribution among stages. In this research, we propose software for the separate optimization of the trajectory of a launch rocket, maximizing the payload weight and the global design, while varying the power plant selection. The launch is mathematically modeled considering its propulsive, gravitational, and aerodynamical aspects. The ascent trajectory is optimized by discretizing the trajectory using structural and physical constraints, and the design accounts for the mass and power plant of each stage. The optimization algorithm is checked against various real rockets and other modeling algorithms, obtaining differences of up to 9%

Conceptual design and research on the thermal performance of a martian human base

Human arrival on Mars is one of the most ambitious goals of the various space agencies. Although interest in the planet may appear to be recent, there is ample evidence to show that mankind turned its attention to Mars several centuries ago. However, it was not until the dawn of the space age that this interest shifted from mere speculation to a growing body of scientific and technical information. Unlike Earth, Mars is a planet whose current conditions are not suitable for life of any kind. The main aspects that condition the Martian environment, such as the atmosphere, temperature, radiation and soil, will be briefly analysed. The house of the first inhabitants of the red planet must meet a series of basic requirements, including simplicity, strength and ensuring adequate conditions of habitability and psychological well-being. A conceptual habitat design based on a structure manufactured entirely on Earth is presented. One of the most important challenges engineers of the future will face in the event of a human arrival on Mars is the thermal control of houses. Unlike Earth, the average temperature on Mars is around 60 °C, which makes it essential to use very precise thermal control techniques. A theoretical thermal analysis of the designed base will be carried out, checking the influence of a set of parameters, and a particular case will be performed with ESATAN software (a leading tool in the European space sector for ESA missions) together with a sensibility analysis to the thermal model main parameters. The assessment of the location and the daily temperature variation has been analysed to obtain the best thermal criteria for time–space selection of the base. The results showed the relevance of the insulation of the module with respect to the Mars ground. A thermal insulation method should be implemented in order to ensure the inhabitants’ well-being

A photo‐thermoelectric twist to wireless energy transfer: radial flexible thermoelectric device powered by a high‐power laser beam

Systems for wireless energy transmission (WET) are gaining prominence nowadays. This work presents a WET system based on the photo-thermoelectric effect. With an incident laser beam at λ = 1450 nm, a temperature gradient is generated in the radial flexible thermoelectric (TE) device, with a carbon-based light collector in its center to enhance the photoheating. The three-part prototype presents a unique approach by using a radial TE device with one simple manufacturing process - screen-printing. A TE ink with a polymeric matrix of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate and doped-Poly(vinyl alcohol) with Sb-Bi-Te microparticles is developed (S∽33 µVK−1 and s∽10.31 Sm−1), presenting mechanical and electrical stability. Regarding the device, a full electrical analysis is performed, and the influence of the light collector is investigated using thermal tests, spectrophotometry, and numerical simulations. A maximum output voltage (Vout) of ∽16 mV and maximum power density of ∽25 µWm−2 are achieved with Plaser = 2 W. Moreover, the device's viability under extreme conditions is explored. At T∽180 K, a 25% increase in Vout compared to room-temperature conditions is achieved, and at low pressures (∽10‒6 Torr), an increase of 230% is obtained. Overall, this prototype allows the supply of energy at long distances and remote places, especially for space exploration.Federación Española de Enfermedades Raras | Ref. UID/NAN/50024/2019Federación Española de Enfermedades Raras | Ref. NORTE‐01‐0145‐FEDER022096Fundação para a Ciência e a Tecnologia | Ref. UIDB/04968/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/04968/202

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field