In this work, we compare the thermophysical properties and particle sizes derived from the Mars Science Laboratory (MSL) rover's Ground Temperature Sensor (GTS) of the Bagnold dunes, specifically ...Namib dune, to those derived orbitally from Thermal Emission Imaging System (THEMIS), ultimately linking these measurements to ground-truth particle sizes determined from Mars Hand Lens Imager (MAHLI) images. In general, we find that all three datasets report consistent particle sizes for the Bagnold dunes (~110-350 microns, and are within measurement and model uncertainties), indicating that particle sizes of homogeneous materials determined from orbit are reliable. Furthermore, we examine the effects of two physical characteristics that could influence the modeled thermal inertia and particle sizes, including: 1) fine-scale (cm-m scale) ripples, and 2) thin layering of indurated/armored materials. To first order, we find small scale ripples and thin (approximately centimeter scale) layers do not significantly affect the determination of bulk thermal inertia from orbital thermal data determined from a single nighttime temperature. Modeling of a layer of coarse or indurated material reveals that a thin layer (< ~5 mm; similar to what was observed by the Curiosity rover) would not significantly change the observed thermal properties of the surface and would be dominated by the properties of the underlying material. Thermal inertia and grain sizes of relatively homogeneous materials derived from nighttime orbital data should be considered as reliable, as long as there are not significant sub-pixel anisothermality effects (e.g. lateral mixing of multiple thermophysically distinct materials).
En ne jetant même qu’un bref coup d’œil aux documents iconographiques concernant la comédie grecque, on est immédiatement frappé par la rondeur que confèrent aux personnages leurs multiples ...rembourrages au moins jusqu’au milieu du ive siècle. On constate par ailleurs que vers 350, au moment où commence, au cœur de la comédie moyenne, ce que H. G. Nesselrath a défini comme une période de transition vers la comédie nouvelle, se produit une transformation du corps comique. Ce dernier perd ses re...
Antiquité Nouvelles réflexions sur l’histoire des antiquaires, sur le rôle des barbares dans la chute de Rome ; la recherche sur l’archéologie de l’or et sur l’image ibérique ; actualités sur les ...vases italiotes, les portraits romains, Constantin... Moyen Âge Que sait-on aujourd’hui de l’artiste médiéval, des arts figuratifs carolingiens ? Comptes rendus sur l’image au Moyen Âge, sur l’architecture romane en Espagne, sur l’art à la cour des Luxembourg, sur les Très riches heures de Jean de Berry...
The heat flow and physical properties package (HP$^3$) of the InSight Mars mission is an instrument package designed to determine the martian planetary heat flow. To this end, the package was ...designed to emplace sensors into the martian subsurface and measure the thermal conductivity as well as the geothermal gradient in the 0-5 m depth range. After emplacing the probe to a tip depth of 0.37 m, a first reliable measurement of the average soil thermal conductivity in the 0.03 to 0.37 m depth range was performed. Using the HP$^3$ mole as a modified line heat source, we determined a soil thermal conductivity of 0.039 $\pm$ 0.002 W m$^{-1}$ K$^{-1}$, consistent with the results of orbital and in-situ thermal inertia measurements. This low thermal conductivity implies that 85 to 95\% of all particles are smaller than 104-173 $\mu$m and suggests that any cement contributing to soil cohesion cannot significantly increase grain-to-grain contact areas by forming cementing necks, but could be distributed in the form of grain coatings instead. Soil densities compatible with the measurements are 1211$_{-113}^{+149}$ kg m$^{-3}$, indicating soil porosities of 61 \%.
We use the surface temperature response to Phobos transits as observed by a radiometer on board of the InSight lander to constrain the thermal properties of the uppermost layer of regolith. Modeled ...transit lightcurves validated by solar panel current measurements are used to modify the boundary conditions of a 1D heat conduction model. We test several model parameter sets, varying the thickness and thermal conductivity of the top layer to explore the range of parameters that match the observed temperature response within its uncertainty both during the eclipse as well as the full diurnal cycle. The measurements indicate a thermal inertia of 103+48-24 Jm-2K-1s-1/2 in the uppermost layer of 0.2 to 4 mm, significantly smaller than the thermal inertia of 200 Jm-2K-1s-1/2 derived from the diurnal temperature curve. This could be explained by larger particles, higher density, or a very small amount of cementation in the lower layers.
We present a concept for using a polarization sensitive multispectral lidar to map the seasonal distribution and exchange of volatiles among the reservoirs of the Martian surface and atmosphere. The ...LIDAR instrument will be a multi-wavelength, altitude-resolved, active near-infrared (NIR, with 10 bands around 1.6 microns) instrument to measure the reflected intensity and polarization of backscattered radiation from planetary surfaces and atmospheres. The proposed instrument would be ideally suited for a mission to Mars to comprehensively investigate the nature and seasonal distributions of volatiles and aerosols. The investigation would include the abundance of atmospheric dust and condensed volatiles, surface and cloud/aerosol grain sizes and shapes, ice and dust particle microphysics and also variations in atmospheric chemistry during multiple overflight local times throughout polar night and day. Such an instrument would be ideal for mapping and detection of recently detected CO2 frost phenomena and H2O and CO2 precipitation events in the polar regions of Mars. Herein we discuss the applicability of this instrument to detect and map sublimation/deposition 'mode flips' recently discovered by Brown et al. (2016) using the CRISM passive infrared sensor on Mars Reconnaissance Orbiter.
Les rapports entre littérature et céramique ont fait ces dernières décennies l’objet d’intenses réflexions, qui ont abouti à la reconnaissance de l’autonomie de ces deux arts, mais malheureusement ...bien souvent aussi à leur traitement séparé de la part de savants spécialisés en philologie ou en histoire de l’art. Le théâtre grec, art visuel tout autant que rhétorique, a souffert plus qu’aucun autre genre de ce cloisonnement. Dans ce contexte, le très beau livre d’Oliver Taplin, Pots and Plays,...
The book "Troubling the Waters: Fulfilling the Promise of Quality Public Schooling for Black Children" by Jerome E. Morris, is reviewed (Teachers College Press, 2009).
The rationale for increasing diversity in science, technology, engineering, mathematics, and medicine (STEMM) has evolved over time, but the approaches to making these fields more inclusive have yet ...to achieve large-scale success for racially minoritized populations. Diverse perspectives are necessary to fuel the high-quality research and innovation required to address humanity's greatest challenges and shape our future in a positive way. This article discusses why institutional transformation is required to make STEMM fields inclusive given the disadvantages accumulated by minoritized populations over centuries of denial of opportunity.
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