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The aim of this work is to extract the surface contribution in the martian visible/near-infrared spectra removing the atmospheric components by means of Principal Component Analysis (PCA) and target transformation (TT). The developed technique is suitable for separating spectral components in a data set large enough to enable an effective usage of statistical methods, in support to the more common approaches to remove the gaseous component. In this context, a key role is played by the estimation, from the spectral population, of the covariance matrix that describes the statistical correlation of the signal among different points in the spectrum. As a general rule, the covariance matrix becomes more and more meaningful increasing the size of initial population, justifying therefore the importance of sizable datasets. Data collected by imaging spectrometers, such as the OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité) instrument on board the ESA mission Mars Express (MEx), are particularly suitable for this purpose since it includes in the same session of observation a large number of spectra with different content of aerosols, gases and mineralogy. The methodology presented in this work has been first validated using a simulated dataset of spectra to evaluate its accuracy. Then, it has been applied to the analysis of OMEGA sessions over Nili Fossae and Mawrth Vallis regions, which have been already widely studied because of the presence of hydrated minerals. These minerals are key components of the surface to investigate the presence of liquid water flowing on the martian surface in the Noachian period. Moreover, since a correction for the atmospheric aerosols (dust) component is also applied to these observations, the present work is able to completely remove the atmospheric contribution from the analysed spectra. Once the surface reflectance, free from atmospheric contributions, has been obtained, the Modified Gaussian Model (MGM) has been applied to spectra showing the hydrated phase. Silicates and iron-bearing hydrated minerals have been identified by means of the electronic transitions of Fe 2+ between 0.8 and 1.2 μm, while at longer wavelengths the hydrated mineralogy is identified by overtones of the OH group. Surface reflectance spectra, as derived through the method discussed in this paper, clearly show a lower level of the atmospheric residuals in the 1.9 hydration band, thus resulting in a better match with the MGM deconvolution parameters found for the laboratory spectra of martian hydrated mineral analogues and allowing a deeper investigation of this spectral range. [ABSTRACT FROM AUTHOR]

We obtained 2–4 μm spectra of six M-type asteroids using the SpeX spectrograph at NASA’s Infrared Telescope Facility. We find evidence for hydrated minerals on all six asteroids, including two that were previously thought to be dry. One of our targets, (216) Kleopatra, shows rotational variability in the depth of its 3-μm feature. We also studied three of these asteroids in the 0.8–2.4 μm range using the NICS instrument at the Telescopio Nazionale Galileo (TNG) in La Palma, Spain. The discovery of spectral signatures of hydrated minerals on so many M-types is difficult to reconcile with a highly thermally evolved composition. It has been suggested that the hydrated minerals could have been delivered to M-types via impacts with primitive objects, or that the M-types may actually have primitive compositions that are not represented in meteorite collections. Understanding the origin and type of hydration on these asteroids will help determine which of these interpretations is correct. [ABSTRACT FROM AUTHOR]

The 12-km-wide Vargeão impact structure was formed 123 Myr ago in the Paraná basaltic province (southern Brazil). At this time the province region had a dry climate, although a large brackish aquifer had been formed in the underlying sandstones. It is therefore one of the best terrestrial analogs for studying impact-related products on a dry martian surface environment with preserved ice-rich ground. The basalts within the impact structure display cm-sized breccia veins filled with lithic clasts, glassy remnants, newly formed Fe-oxyhydroxides and secondary phases, such as calcite, phyllosilicates and, subordinately quartz and zeolite. The textural and mineralogical study of these phases demonstrate their hydrothermal origin. Although the very center of the structure has experienced the highest pressures and temperatures, the most developed hydrothermal changes are recognized in an inner collar surrounding the central depression. This inner collar is also the location of major modifications of the rock magnetic properties. These magnetic signatures are related to the distribution of impact-related faults and to the formation of new iron oxides. Geochemical modeling indicate that hydrothermal phases formation required low water/rock ratios. Our observations therefore suggest that hydrothermal alteration took place following the perturbation of the aquifer by the impact, but evidence for hydrothermal circulation is limited in comparison with other impact-related hydrothermal systems. This situation may be explained by the presence of the aquifer below the heat source, such a setting being exceptional for the Earth, but common on Mars. However, the spectroscopic signatures in visible/near infrared images suggest that this kind of impact-related hydrothermal alteration may be still indentified in large impact craters on Mars by orbital instruments. These results does not exclude the possibility that more developed alteration took place in breccias that are today eroded. [ABSTRACT FROM AUTHOR]

Spacecraft observations of atmosphereless Solar System bodies, combined with thermophysical modeling, provide important information about the thermal inertia and degree of surface roughness of these bodies. The thermophysical models rely on various methods of generating topography, the most common being the concave spherical segment. We here compare the properties of thermal emission for a number of different topographies – concave spherical segments, random Gaussians, fractals and parallel sinusoidal trenches – for various illumination and viewing geometries, degrees of surface roughness and wavelengths. We find that the thermal emission is strongly dependent on roughness type, even when the degrees of roughness are identical, for certain illumination and viewing geometries. The systematic usage of any single topography model may therefore bias determinations of thermal inertia and level of roughness. We outline strategies that may be employed during spacecraft observations to disentangle thermal inertia, level of roughness and type of topography. We also compare the numerically complex and time consuming full-scale thermophysical models with a simplified statistical approach, which is fairly easy to implement and quick to run. We conclude that the simplified statistical approach is similar to thermophysical models for cases tested here, which enables the user to analyze huge amounts of spectral data at a low numerical cost. [ABSTRACT FROM AUTHOR]

We present a new method to retrieve column abundances and vertical extent of the water vapor from the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) spectra. The new method enables retrievals from the nighttime TES spectra. The retrieval algorithm employs a new model of the vertical distribution of water vapor in the martian atmosphere. In this model water vapor is confined to a layer of finite height in the lower atmosphere. The atmosphere is dry above this ‘wet’ layer. Within the ‘wet’ layer the water vapor has a constant mixing ratio below the water ice cloud condensation height and is saturated above that height. The new retrieval method simultaneously fits the daytime and nighttime TES spectra for a given location using a single mixing ratio profile. We apply this new method to the TES spectra collected over the site of the Phoenix spacecraft landing during late northern spring and summer. Retrieved daytime column abundances are ∼1–5 pr-μm higher than in the previous TES retrieval. Nighttime column abundances are lower than the daytime abundances by ∼5–10 pr-μm due to assumed exchange with soil and predicted water ice cloud formation. The height of the ‘wet’ layer varies with season, reaching ∼18 km around L s = 80–100° and decreasing to 7–10 km by L s = 140°. Changes in the vertical extent of vapor are consistent with seasonal changes in the intensity of the turbulent mixing in the lower atmosphere and in the water ice cloud condensation height. Water vapor extends by several kilometers above the top of the boundary layer at ∼4 km, suggesting that vertical transport of vapor is not limited to the boundary layer. [ABSTRACT FROM AUTHOR]

In spite of an expected decline in convective activity following the 2007 equinox of Uranus, eight sizable storms were detected on the planet with the near-infrared camera NIRC2, coupled to the adaptive optics system, on the 10-m W.M. Keck telescope on UT 5 and 6 August 2014. All storms were on Uranus’ northern hemisphere, including the brightest storm ever seen in this planet at 2.2 μm, reflecting 30% as much light as the rest of the planet at this wavelength. The storm was at a planetocentric latitude of ∼15°N and reached altitudes of ∼330 mbar, well above the regular uppermost cloud layer (methane-ice) in the atmosphere. A cloud feature at a latitude of 32°N, that was deeper in the atmosphere (near ∼2 bar), was later seen by amateur astronomers. We also present images returned from our HST ToO program, that shows both of these cloud features. We further report the first detection of a long-awaited haze over the north polar region. [ABSTRACT FROM AUTHOR]

Several systematic radiometric errors are known to affect the data collected by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor (MGS). The time-varying wavenumber dependent error that significantly increased in magnitude as the MGS mission progressed is discussed in detail. This error mostly affects spectra of cold (nighttime and polar caps) surfaces and atmospheric spectra in limb viewing geometry. It is proposed here that the source of the radiometric error is a periodic sampling error of the TES interferograms. A simple model of the error is developed that allows predicting its spectral shape for any viewing geometry based on the observed uncalibrated spectrum. Comparison of the radiometric errors observed in the TES spaceviews and those predicted by the model shows an excellent agreement. Spectral shapes of the errors for nadir and limb spectra are simulated based on representative TES spectra. In nighttime and limb spectra, and in spectra of cold polar regions, these radiometric errors can result in an error of ±3–5 K in the retrieved atmospheric and surface temperatures, and significant errors in retrieved opacities of atmospheric aerosols. The model of the TES radiometric error presented here can be used to improve the accuracy of the TES retrievals and increase scientific return from the MGS mission. [ABSTRACT FROM AUTHOR]

Juventae Chasma is a deep depression located north of Valles Marineris on Mars, with four bright mounds or light-toned interior layered deposits (ILDs) extending upwards from the Canyon floor. We present here the results of long-term imaging of Juventae Chasma including mounds A, B, C, and D using multiple datasets. Monohydrated sulfates (MHS) were deposited first on the canyon floor, followed by polyhydrated sulfates (PHS). The upper PHS-dominated units are largely eroded away at Juventae Chasma, but this material is still present in significant abundance at mound B. PHS are observed mixed with MHS in some areas of mounds A and C. Terraces are observed at the upper elevations of mound B that contain PHS at the steeper slopes and appear to be covered with dust on the horizontal surfaces. Current analyses of the MHS-rich unit indicate that kieserite (MgSO 4 ⋅H 2 O) is the primary sulfate component, rather than szomolnokite (FeSO 4 ⋅H 2 O) as previously thought. Formation of kieserite at Juventae Chasma likely required temperatures in the 150–200 °C range. Geochemical modeling is most consistent with dissolution of mafic materials followed by precipitation of kieserite from solution. The dust exhibits ferric signatures and the sand is largely mafic material. Outcrops of olivine- and pyroxene-bearing rocks are best observed along the base of mound C and in the chaotic terrain surrounding mound D. This study summarizes the current understanding of Juventae Chasma and its ILDs using HRSC, HiRISE and CTX data, an expanded laboratory spectral library, and the latest calibrations available for CRISM. [ABSTRACT FROM AUTHOR]

High-resolution mapping by visible and near-infrared orbital spectrometers has revealed a diversity of hydrated mineral deposits on the surface of Mars. Quantitative analysis of mineral abundances within these deposits has the potential to distinguish depositional and diagenetic processes. Such analysis can also provide important constraints on the nature of putative global and local-scale mineralogical transitions on Mars. However, the ability of models to extract quantitative mineral abundances from spectra of mixtures relevant to sedimentary rocks remains largely untested. This is particularly true for clay and sulfate minerals, which often occur as fine-grained components of terrestrial sedimentary rocks and are known to occur in a number of sedimentary deposits on Mars. This study examines the spectral properties of a suite of mixtures containing the Mg-sulfate epsomite mixed with varying proportions of smectitic clay (saponite, nontronite, and montmorrilonite). The goal of this work is to test the ability of checkerboard (linear) and intimate (non-linear) mixing models to obtain accurate estimates of mineral abundances under ideal and controlled laboratory conditions. The results of this work suggest that: (1) spectra of clay–sulfate mixtures can be reproduced by checkerboard and intimate mixing models to within 2% absolute reflectance or single scattering albedo, (2) clay and epsomite abundance can be modeled to within 5 wt.% when particle diameter is optimized, and (3) the lower threshold for modeling clay in spectra of clay–epsomite mixtures is approximately 10 wt.%, below which the models often fail to recognize the presence of clay. [ABSTRACT FROM AUTHOR]

We analyzed spectra acquired at the limb of Titan in the 2006–2013 period by the Cassini/Composite Infrared Spectrometer (CIRS) in order to monitor the seasonal evolution of the thermal, gas composition and aerosol spatial distributions. We are primarily interested here in the seasonal changes after the northern spring equinox and interpret our results in term of global circulation seasonal changes. Data cover the 600–1500 cm −1 spectral range at a resolution of 0.5 or 15.5 cm −1 and probe the 150–500 km vertical range with a vertical resolution of about 30 km. Retrievals of the limb spectra acquired at 15.5 cm −1 resolution allowed us to derive eight global maps of temperature, aerosols and C 2 H 2 , C 2 H 6 and HCN molecular mixing ratios between July 2009 and May 2013. In order to have a better understanding of the global changes taking place after the northern spring equinox, we analyzed 0.5 cm −1 resolution limb spectra to infer the mixing ratio profiles of 10 molecules for some latitudes. These profiles are compared with CIRS observations performed during the northern winter. Our observations are compatible with the coexistence of two circulation cells upwelling at mid-latitudes and downwelling at both poles from at last January 2010 to at least June 2010. One year later, in June 2011, there are indications that the global circulation had reversed compared to the winter situation, with a single pole-to-pole cell upwelling at the north pole and downwelling at the south pole. Our observations show that in December 2011, this new pole-to-pole cell has settled with a downward velocity of 4.4 mm/s at 450 km above the south pole. Therefore, in about two years after the equinox, the global circulation observed during the northern winter has totally reversed, which is in agreement with the predictions of general circulation models. We observe a sudden unexpected temperature decrease above the south pole in February 2012, which is probably related to the strong enhancement of molecular gas in this region, acting as radiative coolers. In July and November 2012, we observe a detached haze layer located around 320–330 km, which is comparable to the altitude of the detached haze layer observed by the Cassini Imaging Science Subsystem (ISS) in the UV. [ABSTRACT FROM AUTHOR]

The research is an integrated effort beginning with telescopic observations and extending through detailed mineralogical characterizations to provide constraints on the albedo, diameter, composition, and meteorite affinity of near-Earth object-potentially hazardous asteroid (NEO-PHA 2007 LE). Results of the analysis indicate a diameter of 0.56 kilometers (km) and an albedo of 0.08. 2007 LE exhibits a 1-μm absorption feature without a discernible Band II feature. Compositional analysis of 2007 LE reveal Fs 17 and Fa 19 values, which are consistent with the Fa and Fs values for the H-type ordinary chondrites (Fs 14.5–18 and Fa 16–20 ) and of Asteroid ( 6 ) Hebe (Fs 17 and Fa 15 ). Spectroscopically, 2007 LE does not appear like the average H-chondrite spectra, exhibiting a reddened spectrum and subdued absorption feature. Further investigation of the meteorite classes yielded a black chondrite, Rose City , which is both similar in mineralogy and spectrally to PHA 2007 LE. Dynamical analysis could not directly link the fall of the Rose City meteorite to 2007 LE. As it stands, 2007 LE and Rose City have a compositional link, and both could come from the same parent body/possible family, one known source of the H chondrites is (6) Hebe. [ABSTRACT FROM AUTHOR]

Sunlit and shaded slopes have a variety of temperatures based on their orientation with respect to the Sun. Generally, greater slope angles lead to higher anisothermality within the field of view. This anisothermality is detected by measuring changing emitted radiance as a function of viewing angle or by measuring the difference in brightness temperatures with respect to observation wavelength. Thermal infrared measurements from the Lunar Reconnaissance Orbiter Diviner Radiometer were used to derive lunar surface roughness via two observation types: (1) nadir multispectral observations with full diurnal coverage and (2) multiple emission angle targeted observations. Measurements were compared to simulated radiance from a radiative equilibrium thermal model and Gaussian slope distribution model. Nadir observations most closely match a 20° RMS slope distribution, and multiple emission angle observations can be modeled using 20–35° RMS slope distributions. Limited sampling of the lunar surface did not show any clear variation in roughness among surface units. Two-dimensional modeling shows that surfaces separated by distances greater than 0.5–5 mm can remain thermally isolated in the lunar environment, indicating the length scale of the roughness features. Non-equilibrium conditions are prevalent at night and near sunrise and sunset, preventing the use of the equilibrium thermal model for roughness derivations using data acquired at these local times. Multiple emission angle observations also show a significant decrease in radiance at high emission angles in both daytime and nighttime observations, and hemispherical emissivity is lower than is apparent from nadir observations. These observations and models serve as a basis for comparison with similar measurements of other airless bodies and as an initial template for the interpretation of TIR measurements acquired under a variety of geometric conditions. [ABSTRACT FROM AUTHOR]

The upper mesosphere and the lower thermosphere of Venus (from 90 to 150 km altitude) seems to play a transition region in photochemistry, dynamics and radiation, but is still very poorly constrained observationally. Since 2006 VIRTIS on board Venus Express has been obtaining limb observations of CO fluorescent infrared emissions in a systematic manner. This study represents the scientific exploitation of this dataset and reports new information on the composition and temperature at those altitudes. This work is focused on the 4.7 μ m emission of CO as observed by VIRTIS, which contains two emission bands, the fundamental and the first hot of the main CO isotope. A specific scheme for a simultaneous retrieval of CO and temperature is proposed, based on results of a comprehensive non-LTE model of these molecular emissions. A forward model containing such non-LTE model is used at the core of an inversion scheme that consists of two steps: (i) a minimization procedure of model-data differences and (ii) a linear inversion around the solution of the first step. A thorough error analysis is presented, which shows that the retrievals of CO and temperature are very noisy but can be improved by suitable averaging of data. These averages need to be consistent with the non-LTE nature of the emissions. Unfortunately, the data binning process reduced the geographical coverage of the results. The obtained retrieval results indicate a global distribution of the CO in the Venus dayside with a maximum around the sub-solar point, and a decrease of a factor 2 towards high latitudes. Also a gradient from noon to the morning and evening sides is evident in the equator, this being smaller at high latitudes. No morning–afternoon differences in the CO concentration are observed, or are comparable to our retrieval errors. All this argues for a CO distribution controlled by dynamics in the lower thermosphere, with a dominant sub-solar to anti-solar gradient. Similar variations are found with the Venus Thermospheric General Circulation Model (VTGCM), but the VIRTIS CO is systematically larger than in the model. The thermal structure obtained by VIRTIS presents a hint of local maximum around 115 km near the terminator at equatorial latitudes, but not at noon, in clear contrast to VTGCM predictions and to an upper mesosphere in pure radiative balance. A few tentative ideas to explain these model-data discrepancies are discussed. [ABSTRACT FROM AUTHOR]

We present an analysis of the VIMS solar occultations dataset, which allows us to extract vertically resolved information on the characteristics of Titan’s atmosphere between ∼100 and 700 km with a vertical resolution of ∼10 km. After a series of data treatment procedures to correct problems in pointing stability and parasitic light, 4 occultations out of 10 are retained. This sample covers different seasons and latitudes of Titan. The transmittances show clearly the evolution of the haze, with the detection of the detached layer at ∼310 km in September 2011 at mid-northern latitudes. Through the inversion of the transmission spectra with a line-by-line radiative transfer code we retrieve the vertical distribution of CH 4 and CO mixing ratio. For methane inversion we use its 1.4, 1.7 and 2.3 μm bands. The first two bands are always in good agreement and yield an average stratospheric abundance of 1.28 ± 0.08%, after correcting for forward-scattering effects, with no significant differences between the occultations. This is significantly less than the value of 1.48% obtained by the GCMS/Huygens instrument. We find that the 2.3 μm band cannot be used for the extraction of methane abundance because it is blended with other absorptions, not included in our atmospheric model. The analysis of the residual spectra after the inversion shows that such additional absorptions are present through a great part of the VIMS wavelength range. We attribute many of these bands, including the one at 2.3 μm, to gaseous ethane, whose near-infrared spectrum is not well modeled yet. Ethane also contributes significantly to the strong absorption at 3.2–3.5 μm that was previously attributed only to C–H stretching bands from aerosols. Ethane bands may affect the surface windows too, especially at 2.7 μm. Other residual bands are generated by stretching modes of C–H, C–C and C–N bonds. In addition to the C–H stretch from aliphatic hydrocarbons at 3.4 μm, we detect a strong and narrow absorption at 3.28 μm which we tentatively attribute to the presence of PAHs in the stratosphere. C–C and C–N stretching bands are possibly present between 4.3 and 4.5 μm. Finally, we obtain the CO mixing ratio between 70 and 170 km, through the inversion of its 4.7 μm band. The average result of 46 ± 16 ppm is in good agreement with previous studies. [ABSTRACT FROM AUTHOR]

We present phase curves for Venus in the 1–2 μm wavelength region, acquired with IR1 and IR2 on board Akatsuki (February–March 2011). A substantial discrepancy with the previously-published curves was found in the small phase angle range (0–30°). Through analysis by radiative-transfer computation, it was found that the visibility of larger (∼1 μm or larger) cloud particles was significantly higher than in the standard cloud model. Although the cause is unknown, this may be related to the recently reported increase in the abundance of SO 2 in the upper atmosphere. It was also found that the cloud top is located at ∼75 km and that 1-μm particles exist above the cloud, both of these results being consistent with recent studies based on the Venus Express observations in 2006–2008. Further monitoring, including photometry for phase curves, polarimetry for aerosol properties, spectroscopy for SO 2 abundance, and cloud opacity measurements in the near-infrared windows, is required in order to understand the mechanism of this large-scale change. [ABSTRACT FROM AUTHOR]

We aim to provide a taxonomic and compositional characterization of Multiple Asteroid Systems (MASs) located in the main belt (MB) using visible (0.45–0.85 μm) and near-infrared (0.7–2.5 μm) spectral data of 42 MB MASs. The compositional and mineralogical analysis is applied to determine meteorite analogs for the MASs, which, in turn, are applied to the MAS density measurements of Marchis et al. (Marchis et al. [2012]. Icarus 221, 1130–1161) to estimate the porosity of the systems. The macroporosities are used to evaluate the primary MAS formation hypotheses. Our spectral survey consists of visible and near-infrared spectral data. The visible observing campaign includes 25 MASs obtained using the Southern Astrophysical Research (SOAR) telescope with the Goodman High Throughput Spectrometer. The infrared observing campaign includes 34 MASs obtained using the NASA Infrared Telescope Facility (IRTF) with the SpeX spectragraph. For completeness, both visible and NIR data sets are supplemented with publicly available data, and the data sets are combined where possible. The MASs are classified using the Bus-DeMeo taxonomic system. In order to determine mineralogy and meteorite analog, we perform a NIR spectral band parameter analysis using a new analysis routine, the Spectral Analysis Routine for Asteroids (SARA). The SARA routine determines band centers, areas, and depths by utilizing the diagnostic absorption features near 1- and 2-μm due to Fe 2+ crystal field transitions in olivine + pyroxene and pyroxene, respectively. The band parameter analysis provides the Gaffey subtype for the S-complex MASs; the relative abundance olivine-to-pyroxene ratio; and olivine and pyroxene modal abundances for S-complex and V-type MASs. This mineralogical information is then applied to determine meteorite analogs. Through applying calibration studies, we are able to determine the H , L , and LL meteorite analogs for 15 MASs with ordinary chondrite-like (OC) mineralogies. We observe an excess (10/15) of LL -like mineralogies. Of the ten MASs with LL -like mineralogies, seven are consistent with Flora family membership, supporting the hypothesis that the Flora family is a source of LL -like NEAs and LL chondrites on Earth. Our band parameter analysis is unable to clearly distinguish between the HED subgroups for the 6 V-type MASs. Using the measured densities of the meteorite analog and the MAS densities from Marchis et al. (Marchis et al. [2012]. Icarus 221, 1130–1161), we estimate the macroporosity for 13 MASs. We find that all of the MASs with estimated macroporosities are in agreement with formation hypotheses. [ABSTRACT FROM AUTHOR]

High-resolution spectra of Pluto in the 1.66 μm region, recorded with the VLT/CRIRES instrument in 2008 (2 spectra) and 2012 (5 spectra), are analyzed to constrain the spatial and vertical distribution of methane in Pluto’s atmosphere and to search for mid-term (4 year) variability. A sensitivity study to model assumptions (temperature structure, surface pressure, Pluto’s radius) is performed. Results indicate that (i) no variation of the CH 4 atmospheric content (column-density or mixing ratio) with Pluto rotational phase is present in excess of 20%, (ii) CH 4 column densities show at most marginal variations between 2008 and 2012, with a best guess estimate of a ∼20% decrease over this time frame. As stellar occultations indicate that Pluto’s surface pressure has continued to increase over this period, this implies a concomitant decrease of the methane mixing ratio (iii) the data do not show evidence for an altitude-varying methane distribution; in particular, they imply a roughly uniform mixing ratio in at least the first 22–27 km of the atmosphere, and high concentrations of low-temperature methane near the surface can be ruled out. Our results are also best consistent with a relatively large (>1180 km) Pluto radius. Comparison with predictions from a recently developed global climate model indicates that these features are best explained if the source of methane occurs in regional-scale CH 4 ice deposits, including both low latitudes and high Northern latitudes, evidence for which is present from the rotational and secular evolution of the near-IR features due to CH 4 ice. Our “best guess” predictions for the New Horizons encounter in 2015 are: a 1184 km radius, a 17 μbar surface pressure, and a 0.44% CH 4 mixing ratio with negligible longitudinal variations. [ABSTRACT FROM AUTHOR]

The Venus thermal radiation spectrum exhibits the signature of CO 2 absorption bands. By means of inversion techniques, those bands enable the retrieval of atmospheric temperature profiles. We have analyzed VIRTIS-M-IR night-side data obtaining high-resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. This analysis is specific to three Venus Express orbits where the vortex presents different dynamical configurations. The cold collar is clearly distinguishable centered at ∼62 km (∼100 mbar) altitude level. On average, the cold collar is more than 15 K colder than the pole, but its specific temperature varies with time. In the three orbits under investigation the South Polar Vortex appears as a vertically extended hot region close to the pole and squeezed by the cold collar between altitudes 55 and 67 km but spreading equatorwards at about 74 km. Both the instantaneous temperature maps and their zonal averages show that the top altitude limit of the thermal signature from the vortex is at ∼80 km altitude, at least on the night-side of the planet. The upper part of the atmosphere (67–85 km) is more homogeneous and has long-scale horizontal temperature differences of about 25 K over horizontal distances of ∼2000 km. The lower part (55–67 km) shows more fine-scale structure, creating the vortex morphology, with thermal differences of up to about 50 K over the same altitude range and ∼500 km horizontal distances. This lower part of the atmosphere is highly affected by the upper cloud deck, leading to stronger local temperature variations and larger uncertainties in the retrieval. From the temperature maps, we also study the vertical stability of different atmospheric layers for the three vortex configurations. The static stability is always positive ( S T > 0) in the considered altitude range (55–85 km) and in the whole polar vortex. The cold collar is the most vertically stable structure at polar latitudes, while the vortex and sub-polar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex exhibit lower stability values than their surroundings. The layer between 62 and 67 km resulted to be the most stable. These results are in good agreement with conclusions from previous radio occultation analyses. [ABSTRACT FROM AUTHOR]

We report on the meeting of the DustPedia collaboration, a project funded within the European Union’s Seventh Framework Programme (FP7) to exploit observations of dust emission from the Herschel Space Observatory for 875 galaxies in the local Universe. [ABSTRACT FROM AUTHOR]

Infrared spectroscopic observations have established the presence of hydrocarbon ices on Pluto and other TNOs, but the abundances of such molecules cannot be deduced without accurate optical constants ( n , k ) and reference spectra. In this paper we present our recent measurements of near- and mid-infrared optical constants for ethane (C 2 H 6 ) and ethylene (C 2 H 4 ) in multiple ice phases and at multiple temperatures. As in our recent work on acetylene (C 2 H 2 ), we also report new measurements of the index of refraction of each ice at 670 nm. Comparisons are made to earlier work where possible, and electronic versions of our new results are made available. [ABSTRACT FROM AUTHOR]

A thermophysical model is presented that considers surface roughness, cast shadows, multiple or single scattering of radiation, visual and thermal infrared self heating, as well as heat conduction in one or three dimensions. The code is suitable for calculating infrared spectral energy distributions for spatially resolved or unresolved minor Solar System bodies without significant atmospheres or sublimation, such as the Moon, Mercury, asteroids, irregular satellites or inactive regions on comet nuclei. It is here used to explore the effects of surface roughness on spatial scales small enough for heat conduction to erase lateral temperature gradients. Analytically derived corrections to one-dimensional models that reproduce the results of three-dimensional modeling are presented. We find that the temperature of terrains with such small-scale roughness is identical to that of smooth surfaces for certain types of topographies and non-scattering material. However, systematic differences between smooth and rough terrains are found for scattering materials, or topographies with prominent positive relief. Contrary to common beliefs, the roughness on small spatial scales may therefore affect the thermal emission of Solar System bodies. [ABSTRACT FROM AUTHOR]

We have investigated the cloud top structure of Venus by analyzing ground-based images taken at the mid-infrared wavelengths of 8.66 μm and 11.34 μm. Venus at a solar phase angle of ∼90°, with the morning terminator in view, was observed by the Cooled Mid-Infrared Camera and Spectrometer (COMICS), mounted on the 8.2-m Subaru Telescope, during the period October 25–29, 2007. The disk-averaged brightness temperatures for the observation period are ∼230 K and ∼238 K at 8.66 μm and 11.34 μm, respectively. The obtained images with good signal-to-noise ratio and with high spatial resolution (∼200 km at the sub-observer point) provide several important findings. First, we present observational evidence, for the first time, of the possibility that the westward rotation of the polar features (the hot polar spots and the surrounding cold collars) is synchronized between the northern and southern hemispheres. Second, after high-pass filtering, the images reveal that streaks and mottled and patchy patterns are distributed over the entire disk, with typical amplitudes of ∼0.5 K, and vary from day to day. The detected features, some of which are similar to those seen in past UV images, result from inhomogeneities of both the temperature and the cloud top altitude. Third, the equatorial center-to-limb variations of brightness temperatures have a systematic day–night asymmetry, except those on October 25, that the dayside brightness temperatures are higher than the nightside brightness temperatures by 0–4 K under the same viewing geometry. Such asymmetry would be caused by the propagation of the migrating semidiurnal tide. Finally, by applying the lapse rates deduced from previous studies, we demonstrate that the equatorial center-to-limb curves in the two spectral channels give access to two parameters: the cloud scale height H and the cloud top altitude z c . The acceptable models for data on October 25 are obtained at H = 2.4–4.3 km and z c = 66–69 km; this supports previous results determined from spacecraft observations. [ABSTRACT FROM AUTHOR]

On 2007 December 16–17, spectra were acquired of the disk of Uranus by the Spitzer Infrared Spectrometer (IRS), ten days after the planet’s equinox, when its equator was close to the sub-Earth point. This spectrum provides the highest-resolution broad-band spectrum ever obtained for Uranus from space, allowing a determination of the disk-averaged temperature and molecule composition to a greater degree of accuracy than ever before. The temperature profiles derived from the Voyager radio occultation experiment by Lindal et al. (Lindal, G.F., Lyons, J.R., Sweetnam, D.N., Eshleman, V.R., Hinson, D.P. [1987]. J. Geophys. Res. 92, 14987–15001) and revisions suggested by Sromovsky et al. (Sromovsky, L.A., Fry, P.A., Kim, J.H. [2011]. Icarus 215, 292–312) that match these data best are those that assume a high abundance of methane in the deep atmosphere. However, none of these model profiles provides a satisfactory fit over the full spectral range sampled. This result could be the result of spatial differences between global and low-latitudinal regions, changes in time, missing continuum opacity sources such as stratospheric hazes or unknown tropospheric constituents, or undiagnosed systematic problems with either the Voyager radio-occultation or the Spitzer IRS data sets. The spectrum is compatible with the stratospheric temperatures derived from the Voyager ultraviolet occultations measurements by Herbert et al. (Herbert, F. et al. [1987]. J. Geophys. Res. 92, 15093–15109), but it is incompatible with the hot stratospheric temperatures derived from the same data by Stevens et al. (Stevens, M.H., Strobel, D.F., Herbert, F.H. [1993]. Icarus 101, 45–63). Thermospheric temperatures determined from the analysis of the observed H 2 quadrupole emission features are colder than those derived by Herbert et al. at pressures less than ∼1 μbar. Extrapolation of the nominal model spectrum to far-infrared through millimeter wavelengths shows that the spectrum arising solely from H 2 collision-induced absorption is too warm to reproduce observations between wavelengths of 0.8 and 3.3 mm. Adding an additional absorber such as H 2 S provides a reasonable match to the spectrum, although a unique identification of the responsible absorber is not yet possible with available data. An immediate practical use for the spectrum resulting from this model is to establish a high-precision continuum flux model for use as an absolute radiometric standard for future astronomical observations. [ABSTRACT FROM AUTHOR]

Mid-infrared spectral observations Uranus acquired with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope are used to determine the abundances of C 2 H 2 , C 2 H 6 , CH 3 C 2 H, C 4 H 2 , CO 2 , and tentatively CH 3 on Uranus at the time of the 2007 equinox. For vertically uniform eddy diffusion coefficients in the range 2200–2600 cm 2 s −1 , photochemical models that reproduce the observed methane emission also predict C 2 H 6 profiles that compare well with emission in the 11.6–12.5 μm wavelength region, where the υ 9 band of C 2 H 6 is prominent. Our nominal model with a uniform eddy diffusion coefficient K zz = 2430 cm 2 s −1 and a CH 4 tropopause mole fraction of 1.6 × 10 −5 provides a good fit to other hydrocarbon emission features, such as those of C 2 H 2 and C 4 H 2 , but the model profile for CH 3 C 2 H must be scaled by a factor of 0.43, suggesting that improvements are needed in the chemical reaction mechanism for C 3 H x species. The nominal model is consistent with a CH 3 D/CH 4 ratio of 3.0 ± 0.2 × 10 −4 . From the best-fit scaling of these photochemical-model profiles, we derive column abundances above the 10-mbar level of 4.5 + 01.1/−0.8 × 10 19 molecule-cm −2 for CH 4 , 6.2 ± 1.0 × 10 16 molecule-cm −2 for C 2 H 2 (with a value 24% higher from a different longitudinal sampling), 3.1 ± 0.3 × 10 16 molecule-cm −2 for C 2 H 6 , 8.6 ± 2.6 × 10 13 molecule-cm −2 for CH 3 C 2 H, 1.8 ± 0.3 × 10 13 molecule-cm −2 for C 4 H 2 , and 1.7 ± 0.4 × 10 13 molecule-cm −2 for CO 2 on Uranus. A model with K zz increasing with altitude fits the observed spectrum and requires CH 4 and C 2 H 6 column abundances that are 54% and 45% higher than their respective values in the nominal model, but the other hydrocarbons and CO 2 are within 14% of their values in the nominal model. Systematic uncertainties arising from errors in the temperature profile are estimated very conservatively by assuming an unrealistic “alternative” temperature profile that is nonetheless consistent with the observations; for this profile the column abundance of CH 4 is over four times higher than in the nominal model, but the column abundances of the hydrocarbons and CO 2 differ from their value in the nominal model by less than 22%. The CH 3 D/CH 4 ratio is the same in both the nominal model with its uniform K zz as in the vertically variable K zz model, and it is 10% lower with the “alternative” temperature profile than the nominal model. There is no compelling evidence for temporal variations in global-average hydrocarbon abundances over the decade between Infrared Space Observatory and Spitzer observations, but we cannot preclude a possible large increase in the C 2 H 2 abundance since the Voyager era. Our results have implications with respect to the influx rate of exogenic oxygen species and the production rate of stratospheric hazes on Uranus, as well as the C 4 H 2 vapor pressure over C 4 H 2 ice at low temperatures. [ABSTRACT FROM AUTHOR]

The Moon has areas of magnetized crust (“magnetic anomalies”), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith. [ABSTRACT FROM AUTHOR]

Water–ice-poor, 5-μm-bright material on Saturn’s moon Titan has previously been geomorphologically identified as evaporitic. Here we present a global distribution of the occurrences of the 5-μm-bright spectral unit, identified with Cassini’s Visual Infrared Mapping Spectrometer (VIMS) and examined with RADAR when possible. We explore the possibility that each of these occurrences are evaporite deposits. The 5-μm-bright material covers 1% of Titan’s surface and is not limited to the poles (the only regions with extensive, long-lived surface liquid). We find the greatest areal concentration to be in the equatorial basins Tui Regio and Hotei Regio. Our interpretations, based on the correlation between 5-μm-bright material and lakebeds, imply that there was enough liquid present at some time to create the observed 5-μm-bright material. We address the climate implications surrounding a lack of evaporitic material at the south polar basins: if the south pole basins were filled at some point in the past, then where is the evaporite? [ABSTRACT FROM AUTHOR]

We present a determination of the methane mole fraction in Titan’s stratosphere using spectral measurements by the Upward Looking Infrared Spectrometer (ULIS) of the Descent Imager/Spectral Radiometer (DISR) aboard the Huygens probe. We analyzed the 1.4-μm band of methane for which a complete linelist, down to very low intensities, was recently made available. The DISR/ULIS measurements were used to derive the methane transmittance along the path from the probe to the Sun during the descent from 135 to 29 km. Fitting the transmittance ratios to remove residual instrumental effects, we derived a stratospheric methane mole fraction of 1.44 (+0.27/−0.11)%, taking into account random errors and uncertainties in the spectroscopic parameters. This value is fully consistent with the simultaneous measurement of the methane profile by the Huygens Gas Chromatograph/Mass Spectrometer (GCMS). It disagrees with the ∼1% mixing ratio recently inferred from Cassini/CIRS spectra at low latitudes near 85 km. Possible reasons for the discrepancy and uncertainties in the methane spectroscopic parameters are discussed. [ABSTRACT FROM AUTHOR]

Observations obtained with the near-infrared camera NIRC2, coupled to the adaptive optics system on the 10-m W.M. Keck II telescope on Mauna Kea, Hawaii, on 15 August 2013 at ∼15:30 UT revealed two large “Outburst”-class volcanic eruptions on Io. Follow-up observations five days later showed that both eruptions had substantially faded. The most energetic eruption was at Rarog Patera, at a location near 305°W, 42°S; a smaller one occurred further south at ∼310°W and ∼57°S, close to Heno Patera. Total radiant fluxes at Rarog Patera on August 15 were of order ∼500 GW/sr/μm at wavelengths between 2 and 4 μm, and close to 250 GW/sr/μm at 1.6 μm, indicative of an effective temperature of ∼1040 K over an area of ∼120 km 2 , and a total thermal emission of nearly 8 TW. At Heno Patera the 4-μm flux measured ∼250 GW/sr/μm, and ∼90 GW/sr/μm at 2.2 μm, suggestive of an effective temperature of ∼720 K over an area of more than 300 km 2 , and a total thermal emission of ∼5–6 TW. Fits of the Davies (Davies, A.G. [1996]. Icarus 124(1), 45–61) Io Flow Model indicate that these two eruptions are vigorous and the exposed surfaces are mostly very young, no older than 4–5 min at Rarog Patera and a few hours at Heno Patera. The model fits suggest that in both locations lava fountaining is taking place, a highly-energetic style of volcanism. Using follow-up observations taken between August 20 and September 7 we estimate peak effusion rates between 5 × 10 4 and 10 5 m 3 /s. [ABSTRACT FROM AUTHOR]

We present initial data from our campaign to monitor Io in the near-infrared, beginning in August 2013, using 3.8-μm adaptive optics imaging at Gemini N and 2–5 μm disk-integrated spectroscopy at NASA’s IRTF. Conducted during 2013–2014, these observations are coincident with the ISAS/JAXA EXCEED mission’s continuous monitoring of the Io plasma torus and will enable the speculated effects of volcanic outgassing on the torus to be observed directly, in addition to enabling an assessment of the frequency and properties of large-scale outbursts. On 29 August 2013 we detected a powerful eruption (designated 201308C) on Io at 223.5 ± 2.6°W, 29.1 ± 1.8°N. Emitting between 15 and >25 TW, this event is one of the most powerful eruptions ever seen on Io and falls into the rare “outburst” class. This was the third eruption of this type seen on Io in August 2013, an unprecedented occurrence. Also unprecedented was the charting of the decay in thermal emission over the subsequent days and weeks. Modeling of the outburst spectrum places a lower bound of 1200–1300 K on the eruption temperature, and is suggestive of temperatures 1900 K or higher, typically associated with ultramafic lava composition. The eruption is likely a highly energetic, high-volume lava fountain event. [ABSTRACT FROM AUTHOR]

We have imaged Io in the near-infrared (1–5 μm) with adaptive optics on the 10-m W.M. Keck II and the Gemini North telescopes. We have constructed global maps from the data taken in 2010. Although numerous hot spots are visible, the maps are dominated by two volcanic centers: Loki Patera and Kanehekili Fluctus. We have examined in detail the thermal emission from Janus Patera and Kanehekili Fluctus using images obtained between 2003 and 2010, and have created a timeline of volcanic activity at these locations utilizing data from a wide variety of sources. Based on our data and this timeline we find that the thermal emission from Janus Patera is relatively steady, indicative of an active lava lake. The thermal emission from Kanehekili Fluctus, however, is quite variable, and is indicative of the emplacement of extensive lava flows. In 2010, the thermal emission from this location was ∼10 times higher than ever seen before, indicative of a particularly voluminous eruption of lava. [ABSTRACT FROM AUTHOR]

We have examined the variability of thermal emission from lava flows at Amirani on Io, using measurements of radiant flux from detections by the Galileo Near Infrared Mapping Spectrometer (NIMS) between 1996 and 2001. Amirani is the longest currently active lava flow field in the Solar System and a persistent thermal source in every Galileo NIMS observation that covers its location. We have quantified the thermal emission from hot spots correlated with discrete areas of new lava flow emplacement at points along the length of the Amirani flow field in high spatial resolution NIMS observations in 2000 and 2001. Where discernible, the position of some effusive activity changes from orbit to orbit. We find the implied style of emplacement of lava at Amirani is consistent with pahoehoe-like flows. There is an estimated 50% decrease in discharge rate between 1997 and late 2001, perhaps linked to an outburst eruption in the Amirani vicinity in February 2001. The variability of thermal emission from Amirani is less than that seen at a number of other persistently active ionian volcanoes (such as Prometheus, Culann, and Loki Patera). All of these volcanoes exhibit large increases and decreases in the absolute magnitude of thermal emission (see Matson et al., 2006 [Loki Patera]; Davies, A.G. et al. [2006] . Icarus 184, 460–477 [Prometheus]; and Davies, A.G., Ennis, M.E. [2011]. Icarus 215, 401–416 [Culann]). At Amirani, as at these volcanoes, the thermal emission measured between 1996 and 2001 indicates a persistent, although variable, supply of magma to the surface. In high spatial resolution NIMS observations of hot spots obtained in 2000 and 2001 we estimate the emitted power from active lava flows associated with Amirani to be ∼170 ± 30 GW, which corresponds to total effusion rates (assuming a basaltic composition) from multiple points along the Amirani flow of 34–56 m 3 /s. [ABSTRACT FROM AUTHOR]

Maps of the variation in bolometric Bond albedo and thermal inertia across Rhea and Dione have been produced using various day and nighttime observations, taken by Cassini’s Composite Infrared Spectrometer (CIRS). The albedo maps show the same trend that has been previously observed on these satellites from reflected sunlight and thermal observations: a higher albedo on their leading hemispheres. The thermal inertia maps show two previously unknown anomalous high thermal inertia regions: low latitudes on Dione’s leading hemisphere and the bright ejecta blanket of Rhea’s Inktomi crater. The thermal inertia on Dione increases modestly from a background value of 8 J m −2 K −1 s −1/2 to 11 J m −2 K −1 s −1/2 in a region preferentially bombarded by high-energy electrons. We believe that this region on Dione is probably analogous to the thermally anomalous regions recently discovered at equivalent locations on Mimas and Tethys, dubbed Pac-Man features. The smaller magnitude of Dione’s thermal anomaly, compared to that of Mimas and Tethys, provides additional evidence that surface alteration by high-energy electrons produces these anomalies, as the high-energy electron flux decreases with increasing distance from Saturn. However, unlike on Mimas and Tethys, the thermally anomalous region on Dione does not display a spatially correlated decrease in the IR/UV (0.930 μm/0.338 μm) color ratio, implying that the minimum electron energy threshold of the IR/UV ice surface darkening mechanism is not met on Dione. The average of the mapped bolometric Bond albedos on the leading and trailing hemispheres of Dione are 0.49 ± 0.11 and 0.44 ± 0.13 respectively. On Rhea the thermal inertia increases from a background value of 10 J m −2 K −1 s −1/2 to 19 J m −2 K −1 s −1/2 on the ejecta blanket of Inktomi crater, probably due to a mixture of high and low thermal inertia material in this region, such as a fine- and large-grain ice mixture. This is the first time a thermal inertia anomaly has been associated with an impact crater on an icy saturnian satellite. On Rhea the average of the mapped bolometric Bond albedos on the leading and trailing hemispheres are 0.59 ± 0.11 and 0.56 ± 0.13 respectively. [ABSTRACT FROM AUTHOR]

Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1–10 km) is related to physical properties that can provide information about the origin of those materials. We use Dawn’s Visible and InfraRed (VIR) mapping spectrometer hyperspectral data to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 220 K. Some of the dark and bright features were observed multiple times by VIR in the various mission phases at variable spatial resolution, illumination and observation angles, local solar time, and heliocentric distance. This work presents the first temperature maps and spectral emissivities of several kilometer-scale dark and bright material units on Vesta. Results retrieved from the infrared data acquired by VIR show that bright regions generally correspond to regions with lower temperature, while dark regions correspond to areas with higher temperature. During maximum daily insolation and in the range of heliocentric distances explored by Dawn, i.e. 2.23–2.54 AU, the warmest dark unit found on Vesta rises to a temperature of 273 K, while bright units observed under comparable conditions do not exceed 266 K. Similarly, dark units appear to have higher emissivity on average compared to bright units. Dark-material units show a weak anticorrelation between temperature and albedo, whereas the relation is stronger for bright material units observed under the same conditions. Individual features may show either evanescent or distinct margins in the thermal images, as a consequence of the cohesion of the surface material. Finally, for the two categories of dark and bright materials, we were able to highlight the influence of heliocentric distance on surface temperatures, and estimate an average temperature rate change of 1% following a variation of 0.04 AU in the solar distance. [ABSTRACT FROM AUTHOR]

The 1.27-μm O2(a1Δg) dayglow on Mars is a product of the ozone photolysis by solar UV radiation. The intensity of the O2(a1Δg) emission rate depends on ozone concentration, atmospheric density and kinetic parameters of involved photochemical reactions. In turn, the distribution of ozone is sensitive to the vertical and spatial distribution of water vapor, which is an effective destructor of O3. SPICAM IR on the Mars-Express mission measures the O2(1Δg) dayglow with spectral resolving power of 2200. The results of 147 limb observations from 2004 to 2013 are reported. Limb resolution of the instrument is variable and exceeds the scale height of the atmosphere. The slant emission rate reaches a maximum at the high Northern latitudes at northern and southern springs Ls=0-50° and 160-190°, respectively and a minimum in middle and low latitudes at southern summer Ls=200-300°. We have compared the SPIVAM O2(a1Δg) limb profiles with the General Circulation Model simulation by the Laboratoire de Meteorologie Dynamique (LMD GCM, Lefèvre, F., Lebonnois, S., Montmessin, F., Forget, F. [2004]. J. Geophys. Res. 109, E07004. http://dx.doi.org/10.1029/2004JE002268; Lefèvre, F., et al. [2008]. Nature 454(7207), 971-975) reduced to the vertical resolution of the instrument. The GCM includes the radiative effect of the water clouds and an interactive dust scheme, and well reproduces Martian Climate Sounder (MCS) temperature profiles (Clancy, R. Todd et al. [2012]. J. Geophys. Res. 117, 10. http://dx.doi.org/10.1029/2011JE004018). The model underestimates the emission for Ls=0-50°, Ls=160-180° and overestimates it from Ls=60° to Ls=150° at high Northern latitudes. In the Southern hemisphere the model underestimates the emission for Ls=170-200° and overestimates it for Ls=200-230° at high Southern latitudes. The disagreement could be related to the water vapor distribution as the model reproduces it. The most recent version of the LMD GCM including microphysical representation of cloud formation taking into account the effect of dust scavenging by water ice clouds (Navarro, T., Madeleine, J.-B., Montmessin, F., Forget, F., Spiga, A., Millour, E. [2013]. Modeling of the martian water cycle with an improved representation of water ice clouds. European Planetary Science Congress 2013, EPSC Abstracts, vol. 8, EPSC2013-203) gives much better agreement with SPICAM O2(a1Δg) dayglow limb observations. Characterization of the Mars water cycle by GCMs continues to improve, and the observations of the O2(a1Δg) dayglow offer a powerful tool for its validation. [ABSTRACT FROM AUTHOR]

In order to link infrared observations of dust formed during planet formation in debris disks to mid-infrared spectroscopic data of planetary materials from differentiated terrestrial and asteroidal bodies, we obtained absorption spectra of a representative suite of terrestrial crustal and mantle materials, and of typical martian meteorites. A series of debris disk spectra characterized by a strong feature in the 9.0-9.5μm range (HD23514, HD15407a, HD172555 and HD165014), is comparable to materials that underwent shock, collision or high temperature events. These are amorphous materials such as tektites, SiO2-glass, obsidian, and highly shocked shergottites as well as inclusions from mesosiderites (group A). A second group (BD+20307, Beta Pictoris, HD145263, ID8, HD113766, HD69830, P1121, and Eta Corvi) have strong pyroxene and olivine bands in the 9-12μm range and is very similar to ultramafic rocks (e.g. harzburgite, dunite) (group B). This could indicate the occurrence of differentiated materials similar to those in our Solar System in these other systems. However, mixing of projectile and target material, as well as that of crustal and mantle material has to be taken into account in large scale events like hit-and-run and giant collisions or even large-scale planetary impacts. This could explain the olivine-dominated dust of group B. The crustal-type material of group A would possibly require the stripping of upper layers by grazing-style hit-and run encounters or high energy events like evaporation/condensation in giant collisions. In tidal disruptions or the involvement of predominantly icy/water bodies the resulting mineral dust would originate mainly in one of the involved planetesimals. This could allow attributing the observed composition to a specific body (such as e.g. Eta Corvi). [ABSTRACT FROM AUTHOR]

We present two numerical models designed to reproduce the temperatures of the illuminated Saturn rings as measured by the CASSINI-CIRS instrument. Our models are constrained by all available temperature measurements performed on the illuminated rings since SOI. Both models reproduce well the variations of temperature under any illumination and observation geometry. One model is derived from a purely numerical data mining approach, relying on the implementation of a Neural Network that treats the data set globally. This model is used as a test of coverage completeness of the observational parameter space, driving our ability to characterize the rings thermal response. The second (analytical) model is derived using simple physical considerations, by treating the rings as a surface rather than as a collection of individual particles, combined with an empirical anisotropy function to describe the temperature resulting from the Sun's and Saturn's heating. The thermal response of this ring-surface is parameterized by its Bond albedo and emissivity, thermal relaxation time and a set of geometrical parameters quantifying the anisotropy of the temperature measurements depending on azimuth and elevation of the observer with respect to the ring plane, as well as on the solar elevation. Both models provide formulae to predict the ring temperature, that will ease the benchmarking of future physical models against data. The physical model is applied to fit the temperature of tens of different radial slices, allowing us to constrain the combined emissivity and albedo, thermal relaxation time and anisotropy parameters of the ring slabs with the highest radial resolution achieved so far with CIRS. Using for the first time all observation geometries available for illuminated rings, we are confident that our values are as unbiased as possible against observation geometry. The thermal relaxation time appears to be short, a few tens of minutes, and independent of the radial distance across the whole ring. A study of the temperature anisotropy suggests inter-particle shadowing is important in the B ring and in the outer A ring regions. [ABSTRACT FROM AUTHOR]

This work updates and expands on results of our long-term radar-driven observational campaign of main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (Ockert-Bell, M.E., Clark, B.E., Shepard, M.K., Rivkin, A.S., Binzel, R.P., Thomas, C.A., DeMeo, F.E., Bus, S.J., Shah, S. [2008]. Icarus 195, 206-219; Ockert-Bell, M.E., Clark, B.E., Shepard, M.K., Issacs, R.A., Cloutis, E.A., Fornasier, S., Bus, S.J. [2010]. Icarus 210, 674-692; Shepard, M.K. et al. [2008a]. Icarus 193, 20-38; Shepard, M.K. et al. [2008b]. Icarus 195, 184-205; Shepard, M.K. et al. [2010]. Icarus 215, 547-551). Eighteen of our targets were near-simultaneously observed with radar and those observations are described in Shepard et al. (Shepard, M.K. et al. [2010]. Icarus 215, 547-551). We combine our near-infrared data with available visible wavelength data for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using two different methods, a χ2 search for spectral matches in the RELAB database and parametric comparisons with meteorites. We present four new methods of parametric comparison, including discriminant analysis. Discriminant analysis identifies meteorite type with 85% accuracy. This paper synthesizes the results of these two analog search algorithms and reconciles those results with analogs suggested from radar data (Shepard, M.K. et al. [2010]. Icarus 215, 547-551). We have observed 29 asteroids, 18 in conjunction with radar observations. For eighteen out of twenty-nine objects observed (62%) our compositional predictions are consistent over two or more methods applied. We find that for our Xc and Xk targets the best fit is an iron meteorite for 34% of the samples. Enstatite chondrites were best fits for 6 of our targets (21%). Stony-iron meteorites were best fits for 2 of our targets (7%). A discriminant analysis suggests that asteroids with no absorption band can be compared to iron meteorites and asteroids with both a 0.9 and 1.9 μm absorption band can be compared to stony-iron meteorites. [ABSTRACT FROM AUTHOR]

Highlights: [•] Air rises above midlatitudes, and descends over the poles and equator. [•] Circulation extends from <0.1mbar down to 40bar. [•] South polar vortex at a relative humidity of 5%, extends from 66°S down to 90°S. [•] At midlatitudes there are 2 cloud layers, one above and one below the tropopause. [•] Stratospheric clouds are tops of anticyclones rising up through tropopause. [ABSTRACT FROM AUTHOR]

Highlights: [•] Steep slopes and yardang morphology may be critical for exposing and detecting hematite. [•] The dark mantling material is not a source for the hematite-bearing materials. [•] This work supports the hypothesis that hematite is eroding from a unit in the ILD. [•] The hematite-bearing material is likely a lag deposit. [Copyright &y& Elsevier]

Highlights: [•] Venus CO dayglow variations at 4.7μm. [•] Venus reflectivity at 4.7μm. [•] Variations of temperature at 74 and 111km. [•] Variations of CO mixing ratio at 74 and 104km. [•] Model for the CO (2-1) dayglow excitation. [Copyright &y& Elsevier]

Highlights: [•] The latitudinal distribution of the O2(a1Δ) Venus airglow is measured with VIRTIS-M. [•] The limb profiles vary in intensity and altitude along latitudinal cuts. [•] Significant structural changes are observed over 24-h periods. [•] Secondary peaks occur in limited regions equatorward of the cold collar. [•] Local enhancements of vertical transport possibly cause the observed structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] We observed (101955) Bennu, the target of OSIRIS-REx, with the Spitzer Space Telescope. [•] From these data, we derive a bulk thermal inertia of 310±70Jm−2 K−1 s−1/2. [•] No spectral emissivity features diagnostic of mineralogy are detected. [•] The thermal inertia suggests an average grain size on the scale of several mm to about a cm. [•] The thermophysical properties of Bennu appear to be fairly homogeneous longitudinally. [ABSTRACT FROM AUTHOR]

Highlights: [•] A contrast in stratospheric temperature at equatorial latitudes in 1980 (Voyager) compared to 2009/2010 (Cassini). [•] This temperature contrast implies the period of Saturn’s ‘semiannual’ oscillation is more quasi-semiannual in period. [•] Warmer temperatures and richer concentrations of acetylene and ethane at high latitudes in 1980 compared to 2009/2010. [•] This may be due to increased auroral activity during solar maximum in 1980 compared to solar minimum in 2009/2010. [ABSTRACT FROM AUTHOR]

Highlights: [•] The thermophysical properties of the martian surface are mapped using OMEGA/MEX data. [•] OMEGA thermal inertia is in good agreement with previous studies. [•] Diurnal thermal behaviors attributable to anisothermality are observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Zonal average temperature and cloud parameters of Venus are N–S axial symmetric. [•] Zonal average temperature and cloud parameters are nearly stable with Julian date. [•] The dawn side below 75km is colder than the dusk side and vice versa above 75km. [•] Cloud top altitude decreases from 71km at low/mid-latitudes to 61km at the poles. [•] Cloud particle size increases from mid-latitudes towards the equator and the poles. [Copyright &y& Elsevier]

Highlights: [•] We present FTIR absorption spectra for chondrules, CAIs, fine-grained matrix. [•] Comparison shows similarity with astronomical dust (circumstellar disks, comets). [•] Band ratios may help to investigate chondrule formation in young Solar Systems. [Copyright &y& Elsevier]

Highlights: [•] Small lunar craters are surrounded by granular flow deposits. [•] Extensive insulating surfaces extend beyond the granular flows. [•] The insulating surfaces show no evidence for impact related deposition or erosion. [•] These properties appear common to all small lunar impacts and are ephemeral. [•] The structure of the upper regolith is modified by relatively distant small impacts. [Copyright &y& Elsevier]

Highlights: [•] All non-polar martian dune fields are compared with those in Valles Marineris. [•] Valles Marineris dune fields are qualitatively and quantitatively distinct from other dunes. [•] Differences are attributed to the rifts unusual geologic and topographic setting. [•] Results imply dune field properties are largely influenced by regional environment. [•] Diversity of detected dune sand compositions with primary and secondary minerals. [ABSTRACT FROM AUTHOR]