<p dir="ltr">The climate and habitable potential of a planet is controlled in part by its orbital configuration, including its obliquity, eccentricity, rotation period, and separation from the host star. Recent studies have suggested the exoplanets with higher eccentricity or obliquity than Earth might be able to produce larger biospheres, potentially leading to "super-habitable" worlds. However, high-obliquity and high-eccentricity planets have also been shown to be susceptible to increased water loss, which would decrease the habitable lifetime.</p><p dir="ltr">I use ExoPlaSim, a 3D General Climate Model, to investigate the habitable lifetimes of a diverse range of possible orbital configurations by varying the planetary obliquity (0-90^o), eccentricity (0-0.4), rotation period (6-96 hr), and stellar constant (1350-1650 W/m²). I study each orbital parameter independently while also co-varying obliquity with eccentricity and rotation period for the entire range of stellar constants. I find that stellar constant is the primary control on atmospheric water vapor, but also that the planetary obliquity, eccentricity and rotation period can determine the escape regime. Increasing the obliquity or eccentricity can push the climate into the significant escape regime at lower stellar constants relative to low-obliquity or low-eccentricity planets. Increasing the rotation period at high obliquities maximizes the habitable lifetime of an exoplanet.</p>

<p>The present-day sedimentary rock record on Mars provides insights into the early surface and subsurface geologic processes. Understanding the sediment characteristics in different environments can help to constrain the climate regimes, potential for habitability, and provide a record of ancient surface processes. The research presented in this dissertation uses complementary remote sensing techniques and datasets from rovers at the surface, satellites in orbit, and at terrestrial analogs that are relevant to current Mars exploration to better characterize alteration through water-rock alteration at multiple scales.</p><p>The martian field site for this work is Mt. Sharp, a 5-kilometer-high mountain in Gale crater that is predominantly composed of fluviolacustrine strata overlain by aeolian strata. At the rover-scale, the effects of large clay-mineral rich deposits were characterized using landscape- and hand lens-scale visible images from the Mastcam and MAHLI instruments, and multispectral visible/near-infrared images from Mastcam (445-1013 nm). Detailed analysis of the observed textures and spectral properties showed that the clay-rich deposits preserve the early surface environment, based on their lack of diagenetic features. While the regions immediately surrounding the clay-rich deposit experienced prolonged exposure to water, leading to enhanced alteration zones, and destroying characteristics from the early environment but providing insight into later water-rock processes.</p><p>At the orbital-scale, three visually distinct, dark-toned, and erosion-resistant layers were mapped and characterized using visible to short wave infrared hyperspectral (700-2650 nm) and image data. Two of these units have been identified as either aeolian or lacustrine through in situ rover investigations and the third unit will not be explored in situ so its origin can only be constrained through orbital analyses. We conducted a comparison of the morphological and spectral properties of the two known units to constrain whether their respective environments can be differentiated from orbit and apply this knowledge to the unknown third unit. The composition of all three units is similar, dominated by mafic minerals, suggesting a similar sediment source. The morphology is distinct between the lacustrine and aeolian units, with the unknown unit having similar morphology as the lacustrine unit, suggesting similar environments. We propose that the lacustrine unit in this study likely represent short-timescale transitions between wet and dry environments, where mafic sands are exposed to water prior to burial and lithification. While in the aeolian unit, most water-rock interactions occur upon lithification and later diagenesis. This has climatic implications in terms of the presence of surface water as these units were deposited as part of the original Mt. Sharp strata (i.e., the lacustrine unit) while some mantling existing topography (i.e., the aeolian and unknown units), representing similar processes but at a much later time.</p><p>The terrestrial analog field site for this dissertation was conducted in Iceland which represents a cold and wet/icy climate. We characterized sediments produced through glaciovolcanism and how they are sorted and altered through transport from source to sink along to characterize unique identifiers of glaciovolcanism that can be determined with Mars-relevant techniques. Decorrelation stretched visible images and lab visible/near-infrared reflectance and thermal-infrared emission data sets (400-2500 nm and 1200-400 cm-1, respectively) show that it is possible to differentiate sediments from glaciovolcanic and subaerial volcanic systems. In some glaciovolcanic systems, a high glass abundance (50-90 %) is observed in sediment grains due to the erosion of hyaloclastite and hyalotuff, deposits that form in water- and ice-magma interactions. These glass grains did not readily breakdown physically or chemically during transport, suggesting that they could still be observed on the martian surface today and be used to identify possible glaciovolcanic deposits.</p><p>The research described in this thesis improves the understanding of different geologic environments using remote sensing techniques and their climatic implications. This will help to better constrain early environments on Mars and identify areas where water may have been present through the rock record, as observed from the surface and from orbit.</p>

Recent geodynamic modeling studies suggest that the geometry of structural landforms in the Ouachita Mountains (OM) has been influenced by the reactivation of a weak scar in the mantle-lithosphere during intracontinental orogenesis. As deformation on one-plate planets such as Mars can be considered intracontinental, and impact cratering deeply scarred the Martian lithosphere, we hypothesize that structural geometries on Mars may also reflect heterogenous networks of lithospheric scarring. To investigate this hypothesis, we model the pre-erosional fold structure of the Maumelle Chaotic Zone in the OM to compare fault and fold geometries with that of the seismically-imaged mantle-lithosphere scar. We then numerically model deformation within the Martian crust and mantle-lithosphere in the presence of scarring to understand tectonic reactivation on one-plate planets. We find that structural geometries in the OM are consistent with a subsurface scar, and tectonic landforms on the surface of Mars may indeed reflect deformation generated by a network of lithospheric heterogeneity.

No description available.

<p>Space weathering refers to the gradual spectral, microstructural, and chemical alteration of airless planetary regoliths due to their exposure to the harsh environment of outer space. Solar wind irradiation and micrometeoroid impacts are the primary space weathering processes at work in our solar system. Although the microstructural and compositional effects of space weathering are small, occurring at the sub-micron scale in individual regolith grains, their collective impact on the spectral signature of planetary surfaces is critical. Space weathering is known to change the slope, albedo, and strength of absorption band features of reflectance spectra acquired by ground- and spacecraft-based instrumentation. In this way, space weathering impedes our ability to determine planetary surface compositions from remote sensing data and pair meteorites with their parent bodies. Thanks to decades of research since the Apollo sample return missions, the planetary science community has developed a comprehensive understanding of how space weathering alters the Moon and silicate-rich asteroids. However, the effects of space weathering on primitive, carbon-rich asteroids—which dominate the outer main belt—are more poorly constrained and very complex. This dissertation aims to improve our understanding of how solar wind irradiation and micrometeoroid bombardment modifies the spectral, microstructural, and chemical properties of carbonaceous asteroidal regoliths. To accomplish this goal, this research experimentally simulates constituent space weathering processes in the laboratory on carbon-rich analog materials. A multi-faceted analytical approach including a variety of electron microscopy and spectroscopic techniques is used to probe the spectral, microstructural, and chemical changes induced by experimental space weathering.</p><p>Chapter 1 of this dissertation provides an introduction to space weathering, including a description of the current state of knowledge in the field as well as the motivation for this research. Similarly, chapter 2 provides an overview of the various experimental simulations and coordinated analytical techniques employed in this work. Chapter 3 initiates the discussion of research accomplished during this doctoral program, presenting a detailed characterization of the spectral, microstructural, and chemical effects derived from simulated solar wind irradiation of a carbonaceous asteroid analog material. More specifically, in chapter 1, I perform high flux (~1013 ions/cm2/s), high fluence (1018 ions/cm2) 1 keV H+ and 4 keV He+ irradiation experiments on the Murchison meteorite. Chapter 2 investigates the role of incident ion flux in solar wind space weathering of carbonaceous asteroidal regolith by performing a set of low flux (~1011 ions/cm2/s) and high flux (~1013 ions/cm2/s) H+ and He+ irradiation experiments on Murchison samples. These experiments are the lowest flux solar wind simulations carried out, to date. Finally, chapter 5 presents results from the first <i>combined</i> ion irradiation and heating experiments performed on a carbon-rich analog using in situ transmission electron microscopy (TEM). In situ TEM is a relatively novel technique in the planetary and geological sciences which allows users to observe the physiochemical changes caused by an external stimuli in <i>real time</i>. The experimental approach used in chapter 5 simulates both solar wind irradiation and micrometeoroid impacts, and, thus, probes the cumulative microstructural and compositional modifications induced by these concurrent space weathering processes. In chapters 3 through 5, I compare my results to previous space weathering simulations and observations of lunar and asteroidal returned samples. Findings from this dissertation advance the existing model of space weathering on carbon-rich asteroids, help inform remote sensing observations from the Hayabusa2 and OSIRIS-REx missions which have rendezvoused with C-complex asteroids Bennu and Ryugu, respectively, and provide experimental ground-truth for analyzing returned samples from these missions.</p>

<p>The natural chemical and physical variations that occur within volcanic rocks (petrology) provide critical insights into mantle and crust conditions on terrestrial bodies. Visible/near-infrared (VNIR; 0.3-2.5 µm) and thermal infrared (TIR; 5-50 µm) spectroscopy are the main tools available to remotely characterize these materials from satellites in orbit. However, the accuracy of petrologic information that can be gained from spectra when rocks exhibit complex variations in mineralogy, crystallinity, microtexture, and oxidation state occurring together in natural settings is not well constrained. Here, we compare the spectra of a suite of volcanic planetary analog rocks from the Three Sisters, OR to their mineralogy, chemistry, and microtexture from X-ray diffraction, X-ray fluorescence, and electron microprobe analysis. Our results indicate that TIR spectroscopy is an effective petrologic tool in such rocks for modeling bulk mineralogy, crystallinity, and mineral chemistry. Given a library with appropriate glass endmembers, TIR modeling can derive glass abundance with similar accuracy as other major mineral groups and provide first-order estimates of glass wt.% SiO2 in glass-rich samples, but cannot effectively detect variations in microtexture and minor oxide minerals. In contrast, VNIR spectra often yield non-unique mineralogic interpretations due to overlapping absorption bands from olivine, glass, and Fe-bearing plagioclase. In addition, we find that sub-micron oxides hosted in transparent matrix material that are common in fine-grained extrusive rocks can lower albedo and partially to fully suppress mafic absorption bands, leading to very different VNIR spectra in rocks with the same mineralogy and chemistry. Mineralogical interpretations from VNIR spectra should not be treated as rigorous petrologic indicators, but can supplement TIR-based petrology by providing unique constraints on oxide minerals, microtexture, and alteration processes.</p>

<p dir="ltr">A better understanding of how aerosols interact with light is imperative as space telescopes unveil more about exoplanet atmospheres. To better understand how realistically shaped cloud condensates scatter light, I updated and tested the Exoplanet Cloud Ensemble Scattering System (ExCESS), which measures the scattering intensity and polarization of an ensemble of particles with respect to scattering angle at visible wavelengths. I used ExCESS to measure the scattering of cubic and irregular cuboid potassium chloride (KCl) particles, a likely cloud species in warm (T = 500 - 1000 K) mini-Neptune exoplanets like GJ 1214b. I then outline my changes made to the radiative transfer model, <i>PICASO</i>, that allow for a user-friendly and accurate method to compute reflected light phase curves. With this new capability, I explore the reflected intensity of Kepler-7b assuming different cloud condensates and particle sedimentation efficiencies, and I find that the cloud condensates Al₂O₃ and TiO₂ may contribute more to reflected light intensity than previously expected for hot Jupiters with heterogeneous dayside temperatures. In the final chapter, I input the laboratory data from ExCESS into the scattering functionality of <i>PICASO</i>. I compare single-wavelength (532 nm) reflected light phase curves of GJ 1214b created with rough scattering approximations to those created with robust non-spherical scattering approximations (ExCESS measurements and discrete dipole approximation). I find that two term Henyey-Greenstein phase functions, which act as a rough approximation to cloud scattering, may be useful for estimating the scattering of cubic and irregular particle shapes when rigorous laboratory measurements or non-spherical scattering approximations are unavailable.</p>

[ES] Se pretende configurar un tipo de arquitectura planetaria cuya concepción se establezca en torno a la búsqueda de las necesidades del astronauta como ser humano. A la hora de planificar un recinto planetario, debe tenerse en cuenta cómo combinar la generación de estímulos positivos para acompañar a un astronauta durante una estancia prolongada en el espacio, siendo el propósito del recinto actuar como refugio, junto a otros factores relacionados con el desarrollo de la vida humana dentro de la estructura. Estas consideraciones nos llevan entonces a la humanización de la arquitectura espacial como uno de los objetivos propuestos en esta investigación. La idea es promover el desarrollo de la actividad humana en todas sus formas posibles, dentro de las expectativas que la comunidad científica tiene sobre el posible establecimiento de una colonia humana extraterrestre y tratar de demostrar la capacidad de la arquitectura planetaria una vez que ha sido pensada al servicio de la condición humana. El objetivo es establecer criterios y pautas para la proyección y materialización de hábitats planetarios destinados, entre otras, a contribuir en mantener a los astronautas en el mejor estado físico y emocional posible durante su estancia durante largos periodos de tiempo al interior de dichos hábitats, en función de condiciones de confort ambiental como la iluminación, térmicas, acústicas, materiales, forma y composición, y relación con otros espacios necesarios para un desarrollo favorable, así como protección frente a agentes nocivos externos. De esta manera, se busca el confort y la respuesta positiva de la salud del astronauta, utilizando la arquitectura planetaria para ser considerada de acuerdo con aquellos aspectos relacionados con la funcionalidad, la construcción fuera del entorno terrestre e incluso la forma. Una vez registradas las necesidades arquitectónicas para su conformación, se consideran los aspectos formales relacionados con el hábitat, particularmente el estudio de los materiales autóctonos y el emplazamiento, destacando la importancia de la geología en la arquitectura planetaria, dadas las implicaciones del regolito lunar y marciano en los hábitats naturales a colonizar. / [CA] Es pretén configurar un tipus d'arquitectura planetària la concepció de la qual s'establisca entorn de la cerca de les necessitats de l'astronauta com a ésser humà. A l'hora de planificar un recinte planetari, ha de tindre's en compte com combinar la generació d'estímuls positius per a acompanyar a un astronauta durant una estada prolongada en l'espai, sent el propòsit del recinte actuar com a refugi, al costat d'altres factors relacionats amb el desenvolupament de la vida humana dins de l'estructura. Estes consideracions ens porten llavors a la humanització de l'arquitectura espacial com un dels objectius proposats en esta investigació. La idea és promoure el desenvolupament de l'activitat humana en totes les seues formes possibles, dins de les expectatives que la comunitat científica té sobre el possible establiment d'una colònia humana extraterrestre i tractar de demostrar la capacitat de l'arquitectura planetària una vegada que ha sigut pensada al servici de la condició humana. L'objectiu és establir criteris i pautes per a la projecció i materialització d'hàbitats planetaris destinats, entre altres, a contribuir a mantindre als astronautes en el millor estat físic i emocional possible durant la seua estada durant llargs períodes de temps a l'interior d'estos hàbitats, en funció de condicions de confort ambiental com la il·luminació, tèrmiques, acústiques, materials, forma i composició, i relació amb altres espais necessaris per a un desenvolupament favorable, així com protecció enfront d'agents nocius externs. D'esta manera, es busca el confort i la resposta positiva de la salut de l'astronauta, utilitzant l'arquitectura planetària per a ser considerada d'acord amb aquells aspectes relacionats amb la funcionalitat, la construcció fora de l'entorn terrestre i fins i tot la forma. Una vegada registrades les necessitats arquitectòniques per a la seua conformació, es consideren els aspectes formals relacionats amb l'hàbitat, particularment l'estudi dels materials autòctons i l'emplaçament, destacant la importància de la geologia en l'arquitectura planetària, donades les implicacions del *regolito lunar i marcià en els hàbitats naturals a colonitzar. / [EN] It is intended to configure a type of planetary architecture whose conception is established around the pursuit of the astronaut's needs as a human being. When planning a planetary enclosure, we must then take into consideration how to combine the generation of positive stimuli to accompany an astronaut during an extended stay, the purpose of the enclosure above all as a shelter, and other factors related to the ideal development of human life inside the structure. These considerations then lead us to the humanization of space architecture as one of the goals proposed in this research. The idea is to promote the development of human activity in all of its possible forms, within the expectations that the scientific community has about the possible establishment of an extra-terrestrial human colony and try to demonstrate the capacity of planetary architecture once it has been thought out in service of the human condition. The aim is to establish criteria and guidelines for the projection and materialization of planetary habitats specifically intended for the purpose, among others, of contributing to keeping the astronauts in the best possible physical and emotional state during their stay for long periods of time inside those habitats, based on environmental comfort conditions such as lighting, thermal, acoustic, material, form and composition, and relationship with other spaces necessary for favourable development, as well as protection against external harmful agents. In this way, we seek the comfort and positive response of the astronaut's health, using planetary architecture to be considered in accordance with those aspects related to functionality, construction outside the terrestrial environment and even form. Once the architectural needs for the conformation of the habitat have been recorded, we consider the formal aspects related to the habitat, particularly the study of indigenous material and the location itself, highlighting the importance of geology in planetary architecture, given the implications of the lunar and Martian regolith in the natural habitats to be colonized. / Eid-Macheh Sánchez, Y. (2024). Arquitectura planetaria: análisis de posibles hábitats naturales y artificiales en los entornos lunar y marciano, y su conveniencia [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/213734