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Spacecraft observations revealed that rocks on carbonaceous asteroids, which constitute the most numerous class by composition, can develop millimeter-to-meter-scale fractures due to thermal stresses. However, signatures of this process on the second-most populous group of asteroids, the S-complex, have been poorly constrained. Here, we report observations of boulders’ fractures on Dimorphos, which is the moonlet of the S-complex asteroid (65803) Didymos, the target of NASA’s Double Asteroid Redirection Test (DART) planetary defense mission. We show that the size-frequency distribution and orientation of the mapped fractures are consistent with formation through thermal fatigue. The fractures’ preferential orientation supports that these have originated in situ on Dimorphos boulders and not on Didymos boulders later transferred to Dimorphos. Based on our model of the fracture propagation, we propose that thermal fatigue on rocks exposed on the surface of S-type asteroids can form shallow, horizontally propagating fractures in much shorter timescales (100 kyr) than in the direction normal to the boulder surface (order of Myrs). The presence of boulder fields affected by thermal fracturing on near-Earth asteroid surfaces may contribute to an enhancement in the ejected mass and momentum from kinetic impactors when deflecting asteroids.

Asteroids smaller than 10 km are thought to be rubble piles formed from the reaccumulation of fragments produced in the catastrophic disruption of parent bodies. Ground-based observations reveal that some of these asteroids are today binary systems, in which a smaller secondary orbits a larger primary asteroid. However, how these asteroids became binary systems remains unclear. Here, we report the analysis of boulders on the surface of the stony asteroid (65803) Didymos and its moonlet, Dimorphos, from data collected by the NASA DART mission. The size-frequency distribution of boulders larger than 5 m on Dimorphos and larger than 22.8 m on Didymos confirms that both asteroids are piles of fragments produced in the catastrophic disruption of their progenitors. Dimorphos boulders smaller than 5 m have size best-fit by a Weibull distribution, which we attribute to a multi-phase fragmentation process either occurring during coalescence or during surface evolution. The density per km2 of Dimorphos boulders ≥1 m is 2.3x with respect to the one obtained for (101955) Bennu, while it is 3.0x with respect to (162173) Ryugu. Such values increase once Dimorphos boulders ≥5 m are compared with Bennu (3.5x), Ryugu (3.9x) and (25143) Itokawa (5.1x). This is of interest in the context of asteroid studies because it means that contrarily to the single bodies visited so far, binary systems might be affected by subsequential fragmentation processes that largely increase their block density per km2. Direct comparison between the surface distribution and shapes of the boulders on Didymos and Dimorphos suggest that the latter inherited its material from the former. This finding supports the hypothesis that some asteroid binary systems form through the spin up and mass shedding of a fraction of the primary asteroid.

Images collected during NASA’s Double Asteroid Redirection Test (DART) mission provide the first resolved views of the Didymos binary asteroid system. These images reveal that the primary asteroid, Didymos, is flattened and has plausible undulations along its equatorial perimeter. At high elevations, its surface is rough and contains large boulders and craters; at low elevations its surface is smooth and possesses fewer large boulders and craters. Didymos’ moon, Dimorphos, possesses an intimate mixture of boulders, several asteroid-wide lineaments, and a handful of craters. The surfaces of both asteroids include boulders that are large relative to their host body, suggesting that both asteroids are rubble piles. Based on these observations, our models indicate that Didymos has a surface cohesion ≤ 1 Pa and an interior cohesion of ∼10 Pa, while Dimorphos has a surface cohesion of <0.9 Pa. Crater size-frequency analyzes indicate the surface age of Didymos is 40–130 times older than Dimorphos, with likely absolute ages of ∼ 12.5 Myr and <0.3 Myr, respectively. Solar radiation could have increased Didymos’ spin rate leading to internal deformation and surface mass shedding, which likely created Dimorphos.

Planetary defense efforts rely on estimates of the mechanical properties of asteroids, which are difficult to constrain accurately from Earth. The mechanical properties of asteroid material are also important in the interpretation of the Double Asteroid Redirection Test (DART) impact. Here we perform a detailed morphological analysis of the surface boulders on Dimorphos using images, the primary data set available from the DART mission. We estimate the bulk angle of internal friction of the boulders to be 32.7 ± 2. 5° from our measurements of the roundness of the 34 best-resolved boulders ranging in size from 1.67–6.64 m. The elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing. Finally, we find striking similarities in the morphology of the boulders on Dimorphos with those on other rubble pile asteroids (Itokawa, Ryugu and Bennu). This leads to very similar internal friction angles across the four bodies and suggests that a common formation mechanism has shaped the boulders. Our results provide key inputs for understanding the DART impact and for improving our knowledge about the physical properties, the formation and the evolution of both near-Earth rubble-pile and binary asteroids.

The ASI cubesat LICIACube has been part of the first planetary defense mission DART, having among its scopes to complement the DRACO images to better constrain the Dimorphos shape. LICIACube had two different cameras, LEIA and LUKE, and to accomplish its goal, it exploited the unique possibility of acquiring images of the Dimorphos hemisphere not seen by DART from a vantage point of view, in both time and space. This work is indeed aimed at constraining the tridimensional shape of Dimorphos, starting from both LUKE images of the nonimpacted hemisphere of Dimorphos and the results obtained by DART looking at the impacted hemisphere. To this aim, we developed a semiautomatic Computer Vision algorithm, named VADER, able to identify objects of interest on the basis of physical characteristics, subsequently used as input to retrieve the shape of the ellipse projected in the LUKE images analyzed. Thanks to this shape, we then extracted information about the Dimorphos ellipsoid by applying a series of quantitative geometric considerations. Although the solution space coming from this analysis includes the triaxial ellipsoid found by using DART images, we cannot discard the possibility that Dimorphos has a more elongated shape, more similar to what is expected from previous theories and observations. The result of our work seems therefore to emphasize the unique value of the LICIACube mission and its images, making even clearer the need of having different points of view to accurately define the shape of an asteroid.

The Double Asteroid Redirection Test (DART, NASA) spacecraft revealed that the primary of the (65803) Didymos near-Earth asteroid (NEA) binary system is not exactly the expected spinning top shape observed for other km-size asteroids. Ground based radar observations predicted that such shape was compatible with the uncertainty along the direction of the asteroid spin axis. Indeed, Didymos shows crater and landslide features, and evidence for boulder motion at low equatorial latitudes. Altogether, the primary seems to have undergone sudden structural failure in its recent history, which may even result in the formation of the secondary. The high eccentricity of Didymos sets its aphelion distance inside the inner main belt, where it spends more than 1/3 of its orbital period and it may undergo many more collisions than in the NEA region. In this work, we investigate the collisional environment of this asteroid and estimate the probability of collision with multi-size potential impactors. We analyze the possibility that such impacts produced the surface features observed on Didymos by comparing collisional intervals with estimated times for surface destabilization by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect. We find that collisional effects dominate over potential local or global deformation due to YORP spin up.

Large thrust faults on Mars are caused by lithospheric planetary contraction. The geometry of these faults is linked with the mechanical behavior of the lithosphere. Tharsis, the largest volcano-tectonic province on Mars, controls the global tectonic pattern of the planet. Here, we present a study of five large thrust faults concentric to Tharsis, located between the Thaumasia Highlands and the Argyre impact basin. We applied a 3D structural modeling, using a combination of fault-parallel flow and trishear algorithms to estimate the geometry and kinematics of the faults at depth. The modeled faults show an upper planar part dipping 33° to 40°, rooting with a listric geometry into horizontal levels at 13–27 km depth, with fault slips of 801–3366 m. The general out-of-Tharsis vergence, the listric fault geometries and the deepening of the depth of faulting toward Thaumasia outline an incipient thrust wedge architecture. Assuming that the largest faults rooted at the Brittle-Ductile Transition, we calculate a heat flow at the time of faulting of 24–54 mW m−2. The obtained strength envelopes for dry and wet conditions show that all the strength of the lithosphere was located in the upper half of the crust., Ministerio de Ciencia, Innovación y Universidades, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Large thrust faults on Mars are caused by lithospheric planetary contraction. The geometry of these faults is linked with the mechanical behavior of the lithosphere. Tharsis, the largest volcano-tectonic province on Mars, controls the global tectonic pattern of the planet. Here, we present a study of five large thrust faults concentric to Tharsis, located between the Thaumasia Highlands and the Argyre impact basin. We applied a 3D structural modeling, using a combination of fault-parallel flow and trishear algorithms to estimate the geometry and kinematics of the faults at depth. The modeled faults show an upper planar part dipping 33° to 40°, rooting with a listric geometry into horizontal levels at 13–27 km depth, with fault slips of 801–3366 m. The general out-of-Tharsis vergence, the listric fault geometries and the deepening of the depth of faulting toward Thaumasia outline an incipient thrust wedge architecture. Assuming that the largest faults rooted at the Brittle-Ductile Transition, we calculate a heat flow at the time of faulting of 24–54 mW m−2. The obtained strength envelopes for dry and wet conditions show that all the strength of the lithosphere was located in the upper half of the crust.

During an extensive grid-mapping campaign on Mars' southern hemisphere, we have detected so-called sheet flow deposits, which are defined by distinctive lobate fronts, thin and mostly planar layers, and faint sub-parallel surface lineations. They originate from the high plains of Dryas Mons, a large massif of impact and tectonic origin, and follow the topographic gradient down into the adjacent basins. Their sources often coincide with steep and multi-layered outcrops. This work addresses the formation of these deposits, and if they are related to the unique tectonic and endogenic environment of Dryas Mons. We applied photogeological mapping, age determinations by crater counts, as well as topographic and heat flow measurements in order to reconstruct the evolution of these landforms. The calculated ages (mid to late Amazonian), their location in the mid-latitudes, as well as some specific morphologies like lobate flow fronts are typical for standard viscous-flow features on Mars. In contrast to such viscous-flow features, the sheet flow deposits occur isolated in the Dryas Mons region. Aside from that, major other landforms, typical for viscous-flow features are lacking, like sublimation pits, brain terrain or arcuate deformations. Considering these similarities and differences, we suggest that both landforms viscous-flow features and the sheet flow deposits of Dryas Mons were formed by the involvement of volatiles; however, at varying amounts and by different emplacement processes. As the formation of the sheet flow deposits is located in an area with one of the highest heat flow values planet-wide, we calculated if the heat flow could be a potential trigger for the release of outcropping volatile-rich layers. However, our calculations have shown that the heat flow is still insufficient to enable near-surface melting. Instead, we suggest that the volatiles originate from deep layers affected by magmatic and/or intrusive activities in a tectonically active environm, Ministerio de Ciencia e Innovación (MICINN), European Space Agency, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

En esta charla se habla sobre el estudio de las características físicas y geológicas de los diferentes planetas y lunas del sistema solar y exoplanetas que nos ayudan a entender la importancia y especiales cualidades de la Tierra para mantener el desarrollo de la vida a lo largo de su historia.

Recorrido virtual por el campus de la UA donde se han dispuesto globos de distinto tamaño representando a escala los planetas del sistema solar. Cada planeta mantiene la distancia escalada con respecto a su posición en el sistema solar y relacionado a un espacio físico disponible en el campus de la UA. Se identificará la posición del Sol y, a partir de ahí, se dispondrán e identificarán los planetas.

Las Ciencias Planetarias están en pleno auge gracias al desarrollo y éxito que han tenido las últimas misiones espaciales y las que serán lanzadas en un futuro próximo. El estudio de planetas y cuerpos menores (asteroides y cometas) requiere de un trabajo multidisciplinarios (física, astronomía, geología, ingeniería...) como el que se lleva a cabo en la UA.

During an extensive grid-mapping campaign on Mars' southern hemisphere, we have detected so-called sheet flow deposits, which are defined by distinctive lobate fronts, thin and mostly planar layers, and faint sub-parallel surface lineations. They originate from the high plains of Dryas Mons, a large massif of impact and tectonic origin, and follow the topographic gradient down into the adjacent basins. Their sources often coincide with steep and multi-layered outcrops. This work addresses the formation of these deposits, and if they are related to the unique tectonic and endogenic environment of Dryas Mons. We applied photogeological mapping, age determinations by crater counts, as well as topographic and heat flow measurements in order to reconstruct the evolution of these landforms. The calculated ages (mid to late Amazonian), their location in the mid-latitudes, as well as some specific morphologies like lobate flow fronts are typical for standard viscous-flow features on Mars. In contrast to such viscous-flow features, the sheet flow deposits occur isolated in the Dryas Mons region. Aside from that, major other landforms, typical for viscous-flow features are lacking, like sublimation pits, brain terrain or arcuate deformations. Considering these similarities and differences, we suggest that both landforms viscous-flow features and the sheet flow deposits of Dryas Mons were formed by the involvement of volatiles; however, at varying amounts and by different emplacement processes. As the formation of the sheet flow deposits is located in an area with one of the highest heat flow values planet-wide, we calculated if the heat flow could be a potential trigger for the release of outcropping volatile-rich layers. However, our calculations have shown that the heat flow is still insufficient to enable near-surface melting. Instead, we suggest that the volatiles originate from deep layers affected by magmatic and/or intrusive activities in a tectonically active environm

La investigación presentada en esta Tesis Doctoral ha proporcionado una ampliación sobre el estudio geológico y la caracterización de la litosfera y la corteza de dos de los cuerpos planetarios con más repercusión mediática de nuestro sistema solar: Marte y Europa. Ambos cuerpos planetarios registran una actividad geológica continuada en el tiempo, una condición que ha sido imprescindible, por ejemplo, para mantener las condiciones habitables en nuestro planeta. Así, los estudios y análisis sobre la dinámica global y regional de ambos cuerpos, su estado térmico y estructura, pueden ser de gran interés para seguir avanzando en el conocimiento sobre la evolución de estos dos cuerpos con interesantes historias geológicas..., The research included in this Thesis has provided an additional insight about the geological study and characterization of the lithosphere and crust of two of the most visible planetary bodies in our solar system: Mars and Europa. Both planetary bodies apparently have had an extensive geological activity along its history, a condition that has been essential, for example, to maintain the habitability conditions in our planet. Thus, the studies and analyses on the global and regional geodynamics of both bodies, and their thermal state and structure, can be of great interest to continue improving our knowledge on the evolution of these two worlds with interesting geological histories...

Este trabajo se enmarca en el proyecto PID2019-108851RB que tiene como objetivo precisar las conexiones entre la dieta, y el vino tinto en particular, y la protección frente a la enfermedad del Alzheimer en un entorno de múltiples factores de estilo de vida. El proyecto pretende identificar la(s) molécula(s) fenólicas responsable(s) de los efectos neuroprotectores de los polifenoles en una aproximación realista del escenario in vivo. Este TFM supone el inicio de estas actividades, que han incluido la evaluación del efecto neuroprotector de metabolitos fenólicos biodisponibles en un proceso de estrés oxidativo y neuroinflamatorio que simula condiciones de progresión de la enfermedad de Alzheimer. Se han ensayado, a concentraciones fisiológicas (1, 10 y 50 µM), metabolitos fenólicos de bajo peso molecular resultantes de las biotransformaciones por la microbiota intestinal (ácido 3,4-dihidroxifenilacético, DHPA; ácido 3,4-dihidroxibenzoico (ácido protocateico), PCA; ácido dihidrocafeico, DHCF) y por la conjugación hepática (3-O- sulfato y el ß-D-O glucurónido del ácido dihidrocafeico (DHCFs y DHCFg)) de los polifenoles del vino, mediante células neuronales SH-SY5Y y macrófagos RAW 264.7, en modelos de simulación de estrés oxidativo y de inflamación inducidos con TBHP y LPS, respectivamente. Aunque con distinta eficacia y concentración, los metabolitos fenólicos protegieron a las células de la apoptosis neuronal a través de la atenuación de los niveles de ROS o la reducción de la inflamación. Además, en el modelo de inflamación con los macrófagos, los metabolitos microbianos y, especialmente los derivados conjugados, incrementaron la viabilidad celular e inhibieron la secreción de citoquinas proinflamatorias. En conjunto, este trabajo ha permitido optimizar la aproximación de estudio de estos metabolitos resultantes de los polifenoles de la dieta por sus efectos neuroprotectores y supone un avance en la caracterización de sus propiedades .

[ES] ANTECEDENTES E IMPORTANCIA DE LOS MICROPLÁSTICOS Durante décadas el uso de plásticos se ha extendido tanto a nivel industrial como doméstico, por ello, en la actualidad, los plásticos y su posible impacto medioambiental despiertan gran interés y preocupación. La contaminación del entorno con residuos plásticos, especialmente del medio marino, es uno de los principales problemas que afecta a la sociedad. Pero además, cada vez existe más evidencia de que algunos plásticos de pequeño tamaño, denominados microplásticos, alcanzan la cadena alimentaria, pudiendo ejercer también efectos sobre nuestra salud, aunque éstos hoy en día son desconocidos. Por ello, uno de los objetivos de desarrollo sostenible de las Naciones Unidas y la OMS es el reto de impulsar la investigación sobre el impacto de los plásticos y microplásticos en el medio ambiente y en la salud. De hecho, varias organizaciones internacionales y nacionales han expuesto recientemente la necesidad de una evaluación exhaustiva de la presencia de microplásticos en el medio ambiente, de la exposición humana por vía alimentaria y de sus posibles efectos en la salud. Diversos estudios han demostrado la presencia de microplásticos en alimentos y bebidas de consumo humano, lo que evidencia que estamos expuestos a estas partículas vía ingestión. Sin embargo, hoy en día se desconoce la exposición real, la cantidad, y los posibles efectos en nuestra salud. Así, son necesarios más estudios para poder establecer el nivel de riesgo, exposición y de posible toxicidad, tanto a las partículas por sí mismas como a otros contaminantes y patógenos que podrían llevar asociados. Con el fin de presentar a la sociedad el problema actual de la contaminación medioambiental por plásticos y microplásticos, hemos creado este cómic para niños y adultos que explica de forma fácil y sencilla cómo llegan a nosotros, sus posibles riesgos, así como algunos consejos para ayudar a solucionar este problema que nos afecta a todos, como la impor, [EN] BACKGROUND AND IMPORTANCE OF MICROPLASTICS For decades, the use of plastics has been widespread at both industrial and domestic levels, so plastics and their potential environmental impact are currently of great interest and concern. The contamination of the environment with plastic waste, especially in the marine environment, is one of the main problems affecting society. In addition, there is increasing evidence that some small plastics, called microplastics, reach the food chain and can also have effects on our health, although these are currently unknown. Therefore, one of the sustainable development goals of the United Nations and the WHO is the challenge of promoting research on the impact of plastics and microplastics on the environment and on health. In fact, a number of international and national organizations have recently stated the need for a comprehensive assessment of the presence of microplastics in the environment, of human exposure via food and of their potential health effects. Several studies have demonstrated the presence of microplastics in food and beverages for human consumption, which shows that we are exposed to these particles via ingestion. However, the actual exposure, the amount, and the possible effects on our health are currently unknown. Thus, more studies are needed to establish the level of risk, exposure and possible toxicity, both to the particles themselves and to other pollutants and pathogens that may be associated with them. In order to present to society the current problem of environmental pollution by plastics and microplastics, we have created this comic for children and adults that explains in an easy and simple way how they reach us, their possible risks, as well as some tips to help solve this problem that affects us all, such as the importance of reducing their excessive use and recycling.

In depth knowledge of the thermal and rheological properties of the crust and mantle of Mars is fundamental for constraining the strength of its lithosphere, and thereby for the understanding its geodynamics, tectonics, and thermal evolution. In this context, an interesting debate on Martian crustal composition is ongoing. The presence of highly differentiated rocks at several locations, and their implications for the thermal state, structure, and evolution of the planet are not well understood. Here we systematically explore the effects of crust material properties (specifically thermal conductivity and density) on the thermal and mechanical structure of the Martian lithosphere. For this purpose, we analyze different key indicators of the thermal state, the strength and mechanical behavior of the lithosphere under a wide range of conditions. We do so by considering suitable parameters for both a nominally basaltic Martian crust and an end-member basaltic crust that would include a significant low density and high thermal conductivity component. We find that crust material properties have a strong control over the thermal state of the entire lithosphere, and thereby over the strength of the lithospheric mantle. Although a lower crustal density reduces the brittle strength, the colder geotherm due to a higher thermal conductivity leads to a stronger crust and lithospheric mantle, and therefore to a thicker lithosphere. It also leads to a stronger lithosphere as a whole in terms of total strength and effective elastic thickness, as a consequence of higher crust and mantle contributions. On the other hand, we also investigate the influence of the rheology of Mars' upper mantle on the total strength of its lithosphere. Water content has a large effect on the rheology of the upper mantle. A wet rheology implies a substantial reduction of the mantle contribution to the total strength and effective elastic thickness of the lithosphere, resulting in a significantly weaker l

In depth knowledge of the thermal and rheological properties of the crust and mantle of Mars is fundamental for constraining the strength of its lithosphere, and thereby for the understanding its geodynamics, tectonics, and thermal evolution. In this context, an interesting debate on Martian crustal composition is ongoing. The presence of highly differentiated rocks at several locations, and their implications for the thermal state, structure, and evolution of the planet are not well understood. Here we systematically explore the effects of crust material properties (specifically thermal conductivity and density) on the thermal and mechanical structure of the Martian lithosphere. For this purpose, we analyze different key indicators of the thermal state, the strength and mechanical behavior of the lithosphere under a wide range of conditions. We do so by considering suitable parameters for both a nominally basaltic Martian crust and an end-member basaltic crust that would include a significant low density and high thermal conductivity component. We find that crust material properties have a strong control over the thermal state of the entire lithosphere, and thereby over the strength of the lithospheric mantle. Although a lower crustal density reduces the brittle strength, the colder geotherm due to a higher thermal conductivity leads to a stronger crust and lithospheric mantle, and therefore to a thicker lithosphere. It also leads to a stronger lithosphere as a whole in terms of total strength and effective elastic thickness, as a consequence of higher crust and mantle contributions. On the other hand, we also investigate the influence of the rheology of Mars' upper mantle on the total strength of its lithosphere. Water content has a large effect on the rheology of the upper mantle. A wet rheology implies a substantial reduction of the mantle contribution to the total strength and effective elastic thickness of the lithosphere, resulting in a significantly weaker l, Unión Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICCIN)/FEDER, Universidad Complutense de Madrid/Banco de Santander, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

In depth knowledge of the thermal and rheological properties of the crust and mantle of Mars is fundamental for constraining the strength of its lithosphere, and thereby for the understanding its geodynamics, tectonics, and thermal evolution. In this context, an interesting debate on Martian crustal composition is ongoing. The presence of highly differentiated rocks at several locations, and their implications for the thermal state, structure, and evolution of the planet are not well understood. Here we systematically explore the effects of crust material properties (specifically thermal conductivity and density) on the thermal and mechanical structure of the Martian lithosphere. For this purpose, we analyze different key indicators of the thermal state, the strength and mechanical behavior of the lithosphere under a wide range of conditions. We do so by considering suitable parameters for both a nominally basaltic Martian crust and an end-member basaltic crust that would include a significant low density and high thermal conductivity component. We find that crust material properties have a strong control over the thermal state of the entire lithosphere, and thereby over the strength of the lithospheric mantle. Although a lower crustal density reduces the brittle strength, the colder geotherm due to a higher thermal conductivity leads to a stronger crust and lithospheric mantle, and therefore to a thicker lithosphere. It also leads to a stronger lithosphere as a whole in terms of total strength and effective elastic thickness, as a consequence of higher crust and mantle contributions. On the other hand, we also investigate the influence of the rheology of Mars' upper mantle on the total strength of its lithosphere. Water content has a large effect on the rheology of the upper mantle. A wet rheology implies a substantial reduction of the mantle contribution to the total strength and effective elastic thickness of the lithosphere, resulting in a significantly weaker l

Elysium Planitia and Oxia Planum are plains located near the Martian dichotomy. Lately, both regions have been extensively analyzed due to the major role that they play in the InSight and ExoMars missions. InSight landed in Elysium Planitia and will obtain the first direct measurement of surface heat flow on Mars. Similarly, the Rosalind Franklin rover on ExoMars 2020 will also provide useful information to understand the thermal state of the planet from data acquired in Oxia Planum, which is the preferred landing site. The proximity of the Martian dichotomy to the area surrounding both landing locations is an important source of spatial variability. In this work, we have modeled the heat flow and the subsurface temperature in the regions adjacent to both landing sites considering the regional context. In order to do so, we have solved the heat conduction equation by means of a finite element analysis and by taking into account topography, crustal composition, and crustal and megaregolith thicknesses. Our results indicate that the spatial variation in these parameters for the region surrounding the InSight landing site involves maximum differences in subsurface temperatures and surface heat flows between highlands and lowlands of about 67% and 16%, respectively. In regard to the area surrounding ExoMars landing site, these differences can reach 28% for subsurface temperatures, and 3% for surface heat flows. Crustal and megaregolith thicknesses together with the thermal properties of the megaregolith layer are the most influential factors affecting heat flows and temperature patterns. We also find that regional variations related to the dichotomy boundary are unlikely to have a large effect on the geothermal heat flux at the InSight and ExoMars landing sites.

The surface of the dwarf planet Ceres is considered to be dominated by geological processes typical of small bodies or medium-sized icy bodies, such as impact cratering; there are also features of putative cryovolcanic origin as well as those related to flow of near-surface ice. Extensional features include regional linear troughs, fractures and pit chains, fractures associated with impact craters and with crater floors, and polygonal craters whose walls seem to be structurally controlled. However, no contractional features, which are related to thrust fault activity more typical of large silicate bodies, have been described. Here we report the presence of scarps, ridges and fractures associated with thrust faults, tectonically raised terrains and thrusted craters—all contractional features. These structures closely resemble thrust-fault-related lobate scarps on Mercury and Mars, albeit with lower displacement. They seem more abundant in high-latitude ancient terrains, perhaps owing to illumination effects that aid identification. The observed deformation implies that the crustal material is stronger than water ice but weaker than silicate rocks, consistent with our current knowledge of crustal composition and rheology. These features suggest that large-scale contraction, possibly related to differentiation processes, occurred in the history of Ceres.

The surface of the dwarf planet Ceres is considered to be dominated by geological processes typical of small bodies or medium-sized icy bodies, such as impact cratering; there are also features of putative cryovolcanic origin as well as those related to flow of near-surface ice. Extensional features include regional linear troughs, fractures and pit chains, fractures associated with impact craters and with crater floors, and polygonal craters whose walls seem to be structurally controlled. However, no contractional features, which are related to thrust fault activity more typical of large silicate bodies, have been described. Here we report the presence of scarps, ridges and fractures associated with thrust faults, tectonically raised terrains and thrusted craters—all contractional features. These structures closely resemble thrust-fault-related lobate scarps on Mercury and Mars, albeit with lower displacement. They seem more abundant in high-latitude ancient terrains, perhaps owing to illumination effects that aid identification. The observed deformation implies that the crustal material is stronger than water ice but weaker than silicate rocks, consistent with our current knowledge of crustal composition and rheology. These features suggest that large-scale contraction, possibly related to differentiation processes, occurred in the history of Ceres., Ministerio de Educación y Ciencia (MEC), Ministerio de Educación, Universidad Complutense de Madrid/Banco de Santander, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Elysium Planitia and Oxia Planum are plains located near the Martian dichotomy. Lately, both regions have been extensively analyzed due to the major role that they play in the InSight and ExoMars missions. InSight landed in Elysium Planitia and will obtain the first direct measurement of surface heat flow on Mars. Similarly, the Rosalind Franklin rover on ExoMars 2020 will also provide useful information to understand the thermal state of the planet from data acquired in Oxia Planum, which is the preferred landing site. The proximity of the Martian dichotomy to the area surrounding both landing locations is an important source of spatial variability. In this work, we have modeled the heat flow and the subsurface temperature in the regions adjacent to both landing sites considering the regional context. In order to do so, we have solved the heat conduction equation by means of a finite element analysis and by taking into account topography, crustal composition, and crustal and megaregolith thicknesses. Our results indicate that the spatial variation in these parameters for the region surrounding the InSight landing site involves maximum differences in subsurface temperatures and surface heat flows between highlands and lowlands of about 67% and 16%, respectively. In regard to the area surrounding ExoMars landing site, these differences can reach 28% for subsurface temperatures, and 3% for surface heat flows. Crustal and megaregolith thicknesses together with the thermal properties of the megaregolith layer are the most influential factors affecting heat flows and temperature patterns. We also find that regional variations related to the dichotomy boundary are unlikely to have a large effect on the geothermal heat flux at the InSight and ExoMars landing sites., Unión Europea. H2020, Universidad de Cádiz, Ministerio de Ciencia, Innovación y Universidades (MICINN), Ministerio de Educación, UK Space Agency, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Two recent papers, by Karimi et al. (2016, Icarus 272, 102–113) and Karimi and Dombard (2017, Icarus 282, 34–39), tried to deduce paleo-heat flows for, respectively, Mars and Venus from modeling the viscoelastic relaxation of large impact craters. Indeed, crater relaxation would be consequence of the flow of the lower crust and uppermost mantle. This flow is dependent on temperature, permitting the link with the calculation of thermal profiles and heat flows. Both papers used conductive thermal profiles and constant thermal conductivities for both the crust and upper mantle (equivalent to using linear thermal gradients given there were no mention to crustal or mantle heat sources), and appropriate rheological laws. In the present discussion, we show that the background heat flows contemporaneous to impact craters formation and relaxation obtained by Karimi and co-workers, when used along with the assumptions made by these authors, lead to temperatures that produce massive (even total) lower crust melting in all and at least a substantial part of the cases for, respectively, Venus and Mars. It is clear that the heat flow results presented by Karimi and co-workers suffer of inconsistency between model requirements explicitly indicated (a crust free of melting) and the implications of the obtained basal heat flows (a lowermost crust partially or totally molten). Thus, we consider that the papers by Karimi and co-workers do not give reliable information on the thermal history of Mars and Venus., Ministerio de Economía y Competitividad (MINECO), Universidad de Cádiz, Ministerio de Educación, Cultura y Deporte (MECD), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Elysium Planitia and Oxia Planum are plains located near the Martian dichotomy. Lately, both regions have been extensively analyzed due to the major role that they play in the InSight and ExoMars missions. InSight landed in Elysium Planitia and will obtain the first direct measurement of surface heat flow on Mars. Similarly, the Rosalind Franklin rover on ExoMars 2020 will also provide useful information to understand the thermal state of the planet from data acquired in Oxia Planum, which is the preferred landing site. The proximity of the Martian dichotomy to the area surrounding both landing locations is an important source of spatial variability. In this work, we have modeled the heat flow and the subsurface temperature in the regions adjacent to both landing sites considering the regional context. In order to do so, we have solved the heat conduction equation by means of a finite element analysis and by taking into account topography, crustal composition, and crustal and megaregolith thicknesses. Our results indicate that the spatial variation in these parameters for the region surrounding the InSight landing site involves maximum differences in subsurface temperatures and surface heat flows between highlands and lowlands of about 67% and 16%, respectively. In regard to the area surrounding ExoMars landing site, these differences can reach 28% for subsurface temperatures, and 3% for surface heat flows. Crustal and megaregolith thicknesses together with the thermal properties of the megaregolith layer are the most influential factors affecting heat flows and temperature patterns. We also find that regional variations related to the dichotomy boundary are unlikely to have a large effect on the geothermal heat flux at the InSight and ExoMars landing sites. © 2019 Elsevier Inc.

The surface of the dwarf planet Ceres is considered to be dominated by geological processes typical of small bodies or medium-sized icy bodies, such as impact cratering1,2; there are also features of putative cryovolcanic origin3 as well as those related to flow of near-surface ice4. Extensional features4–6 include regional linear troughs, fractures and pit chains, fractures associated with impact craters and with crater floors, and polygonal craters whose walls seem to be structurally controlled. However, no contractional features, which are related to thrust fault activity more typical of large silicate bodies7–11, have been described. Here we report the presence of scarps, ridges and fractures associated with thrust faults, tectonically raised terrains and thrusted craters—all contractional features. These structures closely resemble thrust-fault-related lobate scarps on Mercury7,8 and Mars9,10, albeit with lower displacement. They seem more abundant in high-latitude ancient terrains, perhaps owing to illumination effects that aid identification. The observed deformation implies that the crustal material is stronger than water ice but weaker than silicate rocks, consistent with our current knowledge of crustal composition12 and rheology13. These features suggest that large-scale contraction, possibly related to differentiation processes, occurred in the history of Ceres. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

Two recent papers, by Karimi et al. (2016, Icarus 272, 102–113) and Karimi and Dombard (2017, Icarus 282, 34–39), tried to deduce paleo-heat flows for, respectively, Mars and Venus from modeling the viscoelastic relaxation of large impact craters. Indeed, crater relaxation would be consequence of the flow of the lower crust and uppermost mantle. This flow is dependent on temperature, permitting the link with the calculation of thermal profiles and heat flows. Both papers used conductive thermal profiles and constant thermal conductivities for both the crust and upper mantle (equivalent to using linear thermal gradients given there were no mention to crustal or mantle heat sources), and appropriate rheological laws. In the present discussion, we show that the background heat flows contemporaneous to impact craters formation and relaxation obtained by Karimi and co-workers, when used along with the assumptions made by these authors, lead to temperatures that produce massive (even total) lower crust melting in all and at least a substantial part of the cases for, respectively, Venus and Mars. It is clear that the heat flow results presented by Karimi and co-workers suffer of inconsistency between model requirements explicitly indicated (a crust free of melting) and the implications of the obtained basal heat flows (a lowermost crust partially or totally molten). Thus, we consider that the papers by Karimi and co-workers do not give reliable information on the thermal history of Mars and Venus.