abstract: The temperature of a planet's surface depends on numerous physical factors, including thermal inertia, albedo and the degree of insolation. Mars is a good target for thermal measurements because the low atmospheric pressure combined with the extreme dryness results in a surface dominated by large differences in thermal inertia, minimizing the effect of other physical properties. Since heat is propagated into the surface during the day and re-radiated at night, surface temperatures are affected by sub-surface properties down to several thermal skin depths. Because of this, orbital surface temperature measurements combined with a computational thermal model can be used to determine sub-surface structure. This technique has previously been applied to estimate the thickness and thermal inertia of soil layers on Mars on a regional scale, but the Mars Odyssey Thermal Emission Imaging System "THEMIS" instrument allows much higher-resolution thermal imagery to be obtained. Using archived THEMIS data and the KRC thermal model, a process has been developed for creating high-resolution maps of Martian soil layer thickness and thermal inertia, allowing investigation of the distribution of dust and sand at a scale of 100 m/pixel. / Dissertation/Thesis / M.S. Geological Sciences 2013

Diante das crises energéticas mundiais é oportuna a retomada de técnicas passivas de climatização de ambientes, como aquelas que consideram a inércia térmica das edificações. No Brasil é reconhecida a sua importância na melhoria do desempenho térmico de habitações, como indicado na norma NBR 15575 que, no método simplificado de avaliação do desempenho térmico, estabelece valores limites para a transmitância térmica e para a capacidade térmica de paredes, de modo a contemplar a influência da inércia térmica. Entretanto, não se dispõe de informações que permitam extrapolar esses critérios para edifícios de escritórios, que têm diferentes dinâmicas de uso e volumetria. Tendo como principal objetivo apresentar recomendações e critérios para o projeto de edifícios de escritórios na cidade de São Paulo, onde a inércia térmica dos ambientes pode contribuir para a redução ou a eliminação do uso de sistemas de ar condicionado, foi desenvolvido o presente trabalho. Para tal foram efetuadas simulações computacionais da resposta térmica de escritórios, analisados com variações nos seguintes parâmetros: área de piso; proporção de área na fachada em relação ao seu volume; nível de ocupação; taxa de ventilação; cor da fachada; sombreamento de aberturas; tipo de parede e temperatura de referência para o conforto térmico dos usuários. De modo geral, os resultados demonstraram que: ambientes ocupados, com paredes de maior capacidade térmica, menor área de piso e maior área na fachada em relação ao volume do ambiente, têm melhor desempenho térmico, especialmente com o uso de cores claras nas fachadas e dispositivos de sombreamento em aberturas. Tais características têm contribuição mais significativa na redução da demanda por climatização de ambientes somente se for adotada uma temperatura de referência do ar interior acima dos valores tipicamente usados nessas edificações. As recomendações e critérios apresentados para o projeto de escritórios consideram o uso de ambientes com ventilação, utilizando-se sistemas de climatização somente em menos de 15% das horas de um ano típico da cidade de São Paulo. / The global energy crises provide a further reason to use passive techniques, such as the thermal inertia, for cooling buildings. In Brazil, the importance of thermal inertia for the improvement of the thermal performance of dwellings is recognized and has been incorporated into the standard NBR 15575. For the assessment of the thermal performance, this standard establishes limit values for the thermal transmittance and the thermal capacity of walls, taking into account the influence of thermal inertia. However, there is no equivalent information available for offices, which can have very different characteristics. This thesis develops recommendations and criteria for the design of office buildings in the city of São Paulo, where the thermal inertia contributes to a reduction of energy consumption for cooling. Parametric simulations of typical offices were performed, varying the following parameters: floor area; façade-surface-area/volume ratio; internal gains (people, equipment etc.); ventilation rate; facade color and shading. The results showed that offices with walls made of components with higher thermal capacity, smaller floor area and larger façade-surface-area/volume ratio have better thermal performance. Light colors of the façade, shading devices and increased ventilation rate provided further improvement in the thermal performance of the offices. These characteristics may have significant contribution in reducing the energy demand for cooling depending on the value of the inside air temperature adopted. The recommendations and criteria presented for design of offices consider the use of air conditioning in less than 15% of the hours in a typical year in the city of São Paulo.

The role of water and volatiles in the solar system is of critical interest in planetary science. Evidence for the past action of water or direct observation of water on a planetary body can indicate the potential to harbor life and is critical to human exploration of the solar system. We study two very different remote sensing techniques that address the issue of identifying water-related processes on the surface of other planetary bodies, and in particular, Mars. The first technique, combined thermal infrared and visible imaging, has been used extensively on Mars for determining the thermal inertia of surface materials. In the second part of this dissertation, we develop a technique that combines remote thermophysical and visible data sets with ground-based field investigations for the identification of sedimentary features at the surfaces of alluvial fans. Several methods for remotely identifying sedimentary features will be explored using thermal and visible images. We combine results from pre-existing ground-based studies with thermal images and ground-based field investigations to develop a robust technique to be used on a variety of alluvial fans. In the third part, we characterize the remote thermophysical and visible properties of specific classes of sedimentary features on alluvial fans using the technique developed in part two. The second remote sensing technique, neutron spectroscopy, has been used on many planetary spacecraft missions for the identification of hydrogen on planetary surfaces. The Dynamic Albedo of Neutrons (DAN) instrument on the upcoming Mars Science Laboratory rover mission represents a new type of neutron detector for planetary spacecraft, with the neutron detectors mounted to a rover on the Martian surface (as opposed to in orbit around the planetary body) and neutron counts that are binned by time, energy, and location (as opposed to just by energy and location). In chapter four, we model expected neutron energies and arrival times for geologic settings where water has altered the chemistry of the near surface using available geochemical data from the Mars Exploration Rovers (MER). Particle transport models are used to determine the sensitivity of neutron detection techniques to the variations in hydrogen abundance, hydrogen layering and chemical composition measured by MER.

abstract: Planetary surface studies across a range of spatial scales are key to interpreting modern and ancient operative processes and to meeting strategic mission objectives for robotic planetary science exploration. At the meter-scale and below, planetary regolith conducts heat at a rate that depends on the physical properties of the regolith particles, such as particle size, sorting, composition, and shape. Radiometric temperature measurements thus provide the means to determine regolith properties and rock abundance from afar. However, heat conduction through a matrix of irregular particles is a complicated physical system that is strongly influenced by temperature and atmospheric gas pressure. A series of new regolith thermal conductivity experiments were conducted under realistic planetary surface pressure and temperature conditions. A new model is put forth to describe the radiative, solid, and gaseous conduction terms of regolith on Earth, Mars, and airless bodies. These results will be used to infer particle size distribution from temperature measurements of the primitive asteroid Bennu to aid in OSIRIS-REx sampling site selection. Moving up in scale, fluvial processes are extremely influential in shaping Earth's surface and likely played an influential role on ancient Mars. Amphitheater-headed canyons are found on both planets, but conditions necessary for their development have been debated for many years. A spatial analysis of canyon form distribution with respect to local stratigraphy at the Escalante River and on Tarantula Mesa, Utah, indicates that canyon distribution is most closely related to variations in local rock strata, rather than groundwater spring intensity or climate variations. This implies that amphitheater-headed canyons are not simple markers of groundwater seepage erosion or megaflooding. Finally, at the largest scale, volcanism has significantly altered the surface characteristics of Earth and Mars. A field campaign was conducted in Hawaii to investigate the December 1974 Kilauea lava flow, where it was found that lava coils formed in an analogous manner to those found in Athabasca Valles, Mars. The location and size of the coils may be used as indicators of local effusion rate, viscosity, and crustal thickness. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

abstract: Many planetary science missions study thermophysical properties of surfaces using infrared spectrometers and infrared cameras. Thermal inertia is a frequently derived thermophysical property that quantifies the ability for heat to exchange through planetary surfaces. To conceptualize thermal inertia, the diffusion equation analogies are extended using a general effusivity term: the square root of a product of conductivity and capacity terms. A hypothetical thermal inductance was investigated for diurnal planetary heating. The hyperbolic heat diffusion equation was solved to derive an augmented thermal inertia. The hypothetical thermal inductance was modeled with negligible effect on Mars. Extending spectral performance of infrared cameras was desired for colder bodies in the outer solar system where peak infrared emission is at longer wavelengths. The far-infrared response of an infrared microbolometer array with a retrofitted diamond window was determined using an OSIRIS-REx—OTES interferometer. An instrument response function of the diamond interferometer-microbolometer system shows extended peak performance from 15 µm out to 20 µm and 40% performance to at least 30 µm. The results are folded into E-THEMIS for the NASA flagship mission: Europa Clipper. Infrared camera systems are desired for the expanding smallsat community that can inherit risk and relax performance requirements. The Thermal-camera for Exploration, Science, and Imaging Spacecraft (THESIS) was developed for the Prox-1 microsat mission. THESIS, incorporating 2001 Mars Odyssey—THEMIS experience, consists of an infrared camera, a visible camera, and an instrument computer. THESIS was planned to provide images for demonstrating autonomous proximity operations between two spacecraft, verifying deployment of the Planetary Society’s LightSail-B, and conducting remote sensing of Earth. Prox-1—THESIS was selected as the finalist for the competed University Nanosatellite Program-7 and was awarded a launch on the maiden commercial SpaceX Falcon Heavy. THESIS captures 8-12 µm IR images with 100 mm optics and RGB color images with 25 mm optics. The instrument computer was capable of instrument commanding, automatic data processing, image storage, and telemetry recording. The completed THESIS has a mass of 2.04 kg, a combined volume of 3U, and uses 7W of power. THESIS was designed, fabricated, integrated, and tested in ASU’s 100K clean lab. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

Diante das crises energéticas mundiais é oportuna a retomada de técnicas passivas de climatização de ambientes, como aquelas que consideram a inércia térmica das edificações. No Brasil é reconhecida a sua importância na melhoria do desempenho térmico de habitações, como indicado na norma NBR 15575 que, no método simplificado de avaliação do desempenho térmico, estabelece valores limites para a transmitância térmica e para a capacidade térmica de paredes, de modo a contemplar a influência da inércia térmica. Entretanto, não se dispõe de informações que permitam extrapolar esses critérios para edifícios de escritórios, que têm diferentes dinâmicas de uso e volumetria. Tendo como principal objetivo apresentar recomendações e critérios para o projeto de edifícios de escritórios na cidade de São Paulo, onde a inércia térmica dos ambientes pode contribuir para a redução ou a eliminação do uso de sistemas de ar condicionado, foi desenvolvido o presente trabalho. Para tal foram efetuadas simulações computacionais da resposta térmica de escritórios, analisados com variações nos seguintes parâmetros: área de piso; proporção de área na fachada em relação ao seu volume; nível de ocupação; taxa de ventilação; cor da fachada; sombreamento de aberturas; tipo de parede e temperatura de referência para o conforto térmico dos usuários. De modo geral, os resultados demonstraram que: ambientes ocupados, com paredes de maior capacidade térmica, menor área de piso e maior área na fachada em relação ao volume do ambiente, têm melhor desempenho térmico, especialmente com o uso de cores claras nas fachadas e dispositivos de sombreamento em aberturas. Tais características têm contribuição mais significativa na redução da demanda por climatização de ambientes somente se for adotada uma temperatura de referência do ar interior acima dos valores tipicamente usados nessas edificações. As recomendações e critérios apresentados para o projeto de escritórios consideram o uso de ambientes com ventilação, utilizando-se sistemas de climatização somente em menos de 15% das horas de um ano típico da cidade de São Paulo. / The global energy crises provide a further reason to use passive techniques, such as the thermal inertia, for cooling buildings. In Brazil, the importance of thermal inertia for the improvement of the thermal performance of dwellings is recognized and has been incorporated into the standard NBR 15575. For the assessment of the thermal performance, this standard establishes limit values for the thermal transmittance and the thermal capacity of walls, taking into account the influence of thermal inertia. However, there is no equivalent information available for offices, which can have very different characteristics. This thesis develops recommendations and criteria for the design of office buildings in the city of São Paulo, where the thermal inertia contributes to a reduction of energy consumption for cooling. Parametric simulations of typical offices were performed, varying the following parameters: floor area; façade-surface-area/volume ratio; internal gains (people, equipment etc.); ventilation rate; facade color and shading. The results showed that offices with walls made of components with higher thermal capacity, smaller floor area and larger façade-surface-area/volume ratio have better thermal performance. Light colors of the façade, shading devices and increased ventilation rate provided further improvement in the thermal performance of the offices. These characteristics may have significant contribution in reducing the energy demand for cooling depending on the value of the inside air temperature adopted. The recommendations and criteria presented for design of offices consider the use of air conditioning in less than 15% of the hours in a typical year in the city of São Paulo.

A presente pesquisa teve como objetivo principal analisar experimentalmente o comportamento térmico de um sistema de cobertura verde leve (CVL) e, também, comparar o comportamento térmico entre os diferentes sistemas de cobertura, frente aos ganhos térmicos no período de transição entre as estações primavera-verão, na cidade de São Carlos-SP. Os sistemas de cobertura em análise foram: 1) aço galvanizado, 2) telha de fibrocimento, 3) laje pré-moldada cerâmica, 4) telha cerâmica e 5) cobertura verde leve (CVL). A CVL caracteriza-se por um sistema construtivo que possui laje pré-moldada cerâmica impermeabilizada com resina poliuretana vegetal, geomanta tridimensional leve e flexível para drenagem, camada reduzida de substrato e grama em sua superfície. As vantagens em relação à utilização das coberturas verdes, em geral, estão relacionadas à regulação de temperaturas, a melhora na eficiência energética das edificações, a capacidade de retenção das águas pluviais, ao aumento das áreas verdes, a atenuação dos efeitos das ilhas de calor, além da contribuição estética e social no ambiente urbano. A metodologia adotada baseou-se na definição do dia típico experimental e nos parâmetros da inércia térmica aplicados aos componentes construtivos da cobertura. As medições experimentais foram realizadas em células de teste no canteiro experimental da Universidade de São Paulo (USP), pelo grupo de ecotecnologias: novos materiais e procedimentos. Foram armazenados em um sistema de aquisição automática de dados, registros referentes às temperaturas do ar externo e interno às células de teste e da temperatura superficial interna dos sistemas de cobertura. Como resultado, a CVL apresentou um bom comportamento no que se refere à atenuação das variações de temperaturas internas à edificação, frente às temperaturas do ar externo. Obteve, também, a menor temperatura superficial na face interna do sistema de cobertura, quando comparada aos outros sistemas construtivos. Por tanto, conclui-se que a CVL constitui-se de alternativa viável para construção, devido a sua capacidade de amortecimento e atraso do fluxo térmico (inércia térmica), contribuindo com o estabelecimento de temperaturas internas mais amenas e, além disso, por fundamentar-se em preceitos de uma arquitetura de maior consonância com o ambiente natural. / The present research main objective was to experimentally analyze the thermal behavior of an extensive green roof system and also to compare different roof system thermal behavior, considering their thermal profits in the period of transition between the stations spring-summer, in the city of São Carlos-SP. The roof systems analyzed were: 1) galvanized steel, 2) earth flax, 3) paving-stone, 4) ceramic tile and 5) extensive green roof. The extensive green roof can be characterized as a constructive system that holds a waterproofed paving-stone with vegetable resin, a slight and flexible three-dimensional geomat, used for draining, a reduced layer of substratum and grass in its surface. The green roofs advantages are mainly related to temperatures regulation, improvement of energy efficiency in constructions, possibility of pluvial waters retention (runoff), increase of green areas, attenuation of heat islands effects, beyond the aesthetic and social contribution for the urban environment. The methodology used was based on the definition of the experimental typical day and the parameters of the thermal inertia applied to the constructive components of the cover. The experimental measurements had been carried in test of cells located in the experimental base of the University of São Paulo (USP), by the group of ecotecnologys: new materials and procedures. They were stored in a system of automatic acquisition of facts, records regarding the temperatures of the internal and external air in the test of cells, and the superficial temperature of the internal roof systems. As a result, the extensive green roof presented a good behavior, considering the attenuation of the construction internal temperatures variations, facing the temperatures of the external air. It presented, also, the lesser superficial temperature of the internal face of the roof system, when compared with the other constructive systems. Therefore, one concludes that the extensive green roof consists of a feasible alternative for construction, due to its capacity of damping and delaying the thermal flow (thermal inertia), contributing to the establishment of pleasant internal temperatures and, moreover, for basing its rules on architecture patterns more sensitive to environmental issues.

A presente pesquisa teve como objetivo principal analisar experimentalmente o comportamento térmico de um sistema de cobertura verde leve (CVL) e, também, comparar o comportamento térmico entre os diferentes sistemas de cobertura, frente aos ganhos térmicos no período de transição entre as estações primavera-verão, na cidade de São Carlos-SP. Os sistemas de cobertura em análise foram: 1) aço galvanizado, 2) telha de fibrocimento, 3) laje pré-moldada cerâmica, 4) telha cerâmica e 5) cobertura verde leve (CVL). A CVL caracteriza-se por um sistema construtivo que possui laje pré-moldada cerâmica impermeabilizada com resina poliuretana vegetal, geomanta tridimensional leve e flexível para drenagem, camada reduzida de substrato e grama em sua superfície. As vantagens em relação à utilização das coberturas verdes, em geral, estão relacionadas à regulação de temperaturas, a melhora na eficiência energética das edificações, a capacidade de retenção das águas pluviais, ao aumento das áreas verdes, a atenuação dos efeitos das ilhas de calor, além da contribuição estética e social no ambiente urbano. A metodologia adotada baseou-se na definição do dia típico experimental e nos parâmetros da inércia térmica aplicados aos componentes construtivos da cobertura. As medições experimentais foram realizadas em células de teste no canteiro experimental da Universidade de São Paulo (USP), pelo grupo de ecotecnologias: novos materiais e procedimentos. Foram armazenados em um sistema de aquisição automática de dados, registros referentes às temperaturas do ar externo e interno às células de teste e da temperatura superficial interna dos sistemas de cobertura. Como resultado, a CVL apresentou um bom comportamento no que se refere à atenuação das variações de temperaturas internas à edificação, frente às temperaturas do ar externo. Obteve, também, a menor temperatura superficial na face interna do sistema de cobertura, quando comparada aos outros sistemas construtivos. Por tanto, conclui-se que a CVL constitui-se de alternativa viável para construção, devido a sua capacidade de amortecimento e atraso do fluxo térmico (inércia térmica), contribuindo com o estabelecimento de temperaturas internas mais amenas e, além disso, por fundamentar-se em preceitos de uma arquitetura de maior consonância com o ambiente natural. / The present research main objective was to experimentally analyze the thermal behavior of an extensive green roof system and also to compare different roof system thermal behavior, considering their thermal profits in the period of transition between the stations spring-summer, in the city of São Carlos-SP. The roof systems analyzed were: 1) galvanized steel, 2) earth flax, 3) paving-stone, 4) ceramic tile and 5) extensive green roof. The extensive green roof can be characterized as a constructive system that holds a waterproofed paving-stone with vegetable resin, a slight and flexible three-dimensional geomat, used for draining, a reduced layer of substratum and grass in its surface. The green roofs advantages are mainly related to temperatures regulation, improvement of energy efficiency in constructions, possibility of pluvial waters retention (runoff), increase of green areas, attenuation of heat islands effects, beyond the aesthetic and social contribution for the urban environment. The methodology used was based on the definition of the experimental typical day and the parameters of the thermal inertia applied to the constructive components of the cover. The experimental measurements had been carried in test of cells located in the experimental base of the University of São Paulo (USP), by the group of ecotecnologys: new materials and procedures. They were stored in a system of automatic acquisition of facts, records regarding the temperatures of the internal and external air in the test of cells, and the superficial temperature of the internal roof systems. As a result, the extensive green roof presented a good behavior, considering the attenuation of the construction internal temperatures variations, facing the temperatures of the external air. It presented, also, the lesser superficial temperature of the internal face of the roof system, when compared with the other constructive systems. Therefore, one concludes that the extensive green roof consists of a feasible alternative for construction, due to its capacity of damping and delaying the thermal flow (thermal inertia), contributing to the establishment of pleasant internal temperatures and, moreover, for basing its rules on architecture patterns more sensitive to environmental issues.

Un gran porcentaje de las viviendas construidas en Latino América son producto de la autoconstrucción, es decir, no cuentan con estudios preliminares, licencias de construcción, supervisión profesional, son construidas con materiales inadecuados, presentan deficiencia estructural y están ubicadas en zonas no aptas para la construcción. Esto genera peligro a la población, a pesar de que se realice mediante procesos constructivos convencionales sugeridos y asistidos por los maestros de obra. En los primeros meses de 2017, se registraron intensas lluvias debido al Fenómeno del Niño Costero, y se generaron importantes daños en viviendas y carreteras en la Costa de Latino América. Las obras de reconstrucción no se han realizado y existe una gran cantidad de familias damnificadas que esperan acceder a una vivienda segura. En la presente investigación se desarrolló la propuesta de un diseño general de vivienda modular sostenible basado en la Construcción Vernácula a través del uso de materiales eficientes como la caña, la madera, la fibra paja y el barro. / A large percentage of homes built in Latin America are the result of the self-construction, which in most cases means, they do not have preliminary studies, building permits, professional supervision, are built with inadequate materials have structural deficiency and are located in unsuitable areas for construction; despite the fact that it is carried out through conventional constructive processes suggested and assisted by the construction masters it still generates danger to the population. In the first months of 2017, intense rains were recorded due to the El Niño Coastal Phenomenon, and significant damage was caused to homes and roads in the Latin American Coast. The reconstruction works has not been carried out and there are many families affected who hope to access safe housing. In the present investigation the proposal of a general design of sustainable modular housing based on Vernacular Construction was developed with efficient materials such as cane, wood, straw fiber and mud. / Trabajo de investigación

Ce travail de thèse est consacré à la caractérisation physique de la surface de Mars et à l'étude des facteurs dynamiques la modifiant. Deux aspects sont étudiés. Le premier concerne les propriétés thermo-physiques qui sont un moyen de contraindre les actions que les forces érosives et sédimentaires cumulées sur les temps géologiques ont joué à la surface de Mars. Le second est l'hydratation de la surface de Mars qui est une donnée importante du système climatique martien en tant que réservoir d'eau.Afin de caractériser ces deux propriétés physiques de la surface de Mars, nous avons combiné l'approche orbitale permettant une couverture globale, l'approche in situ qui fournit une interprétation locale robuste et l'utilisation d'outils de simulation des processus physiques. Les données des instruments OMEGA, un spectro-imageur à bord de Mars Express en orbite autour de Mars depuis 2004, et le capteur de température de surface de l'instrument REMS, embarqué à bord de Curiosity et en opération dans le cratère Gale depuis 2012 ont été analysées en détail. Les mesures de température de surface de ces deux instruments ont été inversées pour caractériser les propriétés thermo-physiques de la surface au moyen d'un modèle climatique. Nous présentons la première carte globale de l'inertie thermique de la surface de Mars calculées à partir des données OMEGA et nous mettons en évidence de manière inédite des comportements thermiques spécifiques d'assemblages hétérogènes à la surface de Mars ou de processus physiques négligés.Les informations relatives à l'hydratation de la surface ont pu être extraites des données OMEGA grâce à la prise en compte de mesures en laboratoire et ont été interprétées de concert avec les résultats de plusieurs missions autour ou à la surface de Mars et des simulations climatiques du cycle de l'eau afin de reconstruire l'histoire de cette hydratation. Nous trouvons que l'hydratation est stable tout au long de l'année martienne et qu'elle augmente avec la latitude de manière asymétrique entre les deux hémisphères. La distribution spatiale de l'hydratation coincide avec les zones en contact régulier avec des dépôts de givre, qui apparaît ainsi être à l'origine du processus responsable de l'implémentation de l'eau dans le régolite martien. / This thesis work is devoted to the physical characterization of the Martian surface and to the study of dynamic processes modifying it. Two aspects are addressed. The first concerns the thermo-physical properties which are a mean to putting constraints on to the erosive and sedimentary actions summed over the geologic history. The second is the hydration of the Martian surface which plays, as a planetary reservoir of water, an important role on the Martian climate.In order to characterize these two physical parameters of the Martian surface, we have combined the orbital view which allows a global coverage with in situ measurements, which provides a robust local interpretation, and we have used tools allowing numerical simulations of physical processes. Data from OMEGA, an imaging spectrometer onboard Mars Express orbiting Mars since 2004, and from the ground temperature sensor of the REMS instrument onboard Curiosity have been analyzed in details. Surface temperature measurements from these two instruments have been inverted using a climate model for characterizing the thermo-physical properties of the Martian surface. We present the first global map of the Martian surface thermal inertia constructed from OMEGA data and we directly highlight for the first time some thermal behavior caused by heterogeneous mixtures or neglected physical processes at the surface of Mars.Information regarding the hydration of the Martian surface have been extracted from OMEGA data using a large set of laboratory experiments. This information has been interpreted together with scientific results from multiple mission orbiting or at the surface of Mars and with numerical simulations of the Martian water cycle in order to reconstruct the history of this hydration. We find that the hydration remains stable throughout the whole Martian year and that it increases with latitude with an asymetry between the two hemispheres. The spatial distribution of the hydration fits areas that are in regular contact with water frost, which therefore seems to be involved in the process of water implementation in the Martian regolith.