A chemical composition map for Titan’s surface

2021 ◽  
Author(s):  
Anezina Solomonidou ◽  
Athena Coustenis ◽  
Rosaly Lopes ◽  
Michael Malaska ◽  
Alice Le Gall ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Surface Composition ◽  
Radar Data ◽  
Imaging Data ◽  
Origin And Evolution ◽  
Water Ice ◽  
Atmospheric Scattering ◽  
Geological Processes ◽  
Latitudinal Dependence ◽  
Geomorphological Units

<p>The investigation of Titan’s surface chemical composition is of great importance for the understanding of the atmosphere-surface-interior system of the moon. The Cassini cameras and especially the Visual and infrared Mapping Spectrometer has provided a sequence of spectra showing the diversity of Titan’s surface spectrum from flybys performed during the 13 years of Cassini’s operation. In the 0.8-5.2 μm range, this spectro-imaging data showed that the surface consists of a multivariable geological terrain hosting complex geological processes. The data from the seven narrow methane spectral “windows” centered at 0.93, 1.08, 1.27, 1.59, 2.03, 2.8 and 5 μm provide some information on the lower atmospheric context and the surface parameters. Nevertheless, atmospheric scattering and absorption need to be clearly evaluated before we can extract the surface properties. In various studies (Solomonidou et al., 2014; 2016; 2018; 2019; 2020a, 2020b; Lopes et al., 2016; Malaska et al., 2016; 2020), we used radiative transfer modeling in order to evaluate the atmospheric scattering and absorption and securely extract the surface albedo of multiple Titan areas including the major geomorphological units. We also investigated the morphological and microwave characteristics of these features using Cassini RADAR data in their SAR and radiometry mode. Here, we present a global map for Titan’s surface showing the chemical composition constraints for the various units. The results show that Titan’s surface composition, at the depths detected by VIMS, has significant latitudinal dependence, with its equator being dominated by organic materials from the atmosphere and a very dark unknown material, while higher latitudes contain more water ice. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan’s surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.</p><p>[1] Solomonidou, A., et al. (2014), J. Geophys. Res. Planets, 119, 1729; [2] Solomonidou, A., et al. (2016), Icarus, 270, 85; [3] Solomonidou, A., et al. (2018), J. Geophys. Res. Planets, 123, 489; [4] Solomonidou, A., et al. (2020a), Icarus, 344, 113338; [5] Solomonidou, A., et al. (2020b), A&A 641, A16; [6] Lopes, R., et al. (2016) Icarus, 270, 162; [7] Malaska, M., et al. (2016), Icarus 270, 130; [8] Malaska, M., et al. (2020), Icarus, 344, 113764.</p>

scholarly journals Compositional mapping of Titan’s surface using Cassini VIMS and RADAR data

2021 ◽  
Author(s):  
Anezina Solomonidou ◽  
Athena Coustenis ◽  
Alice Le Gall ◽  
Rosaly Lopes ◽  
Michael Malaska ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Surface Composition ◽  
Radar Data ◽  
California Institute ◽  
Imaging Data ◽  
Atmospheric Scattering ◽  
California Institute Of Technology ◽  
Geological Processes ◽  
Geomorphological Units ◽  
Institute Of Technology

<p>The investigation of Titan’s surface chemical composition is of great importance for the understanding of the atmosphere-surface-interior system of the moon. The Cassini cameras and especially the Visual and infrared Mapping Spectrometer has provided a sequence of spectra showing the diversity of Titan’s surface spectrum from flybys performed during the 13 years of Cassini’s operation. In the 0.8-5.2 μm range, this spectro-imaging data showed that the surface consists of a multivariable geological terrain hosting complex geological processes. The data from the seven narrow methane spectral “windows” centered at 0.93, 1.08, 1.27, 1.59, 2.03, 2.8 and 5 μm provide some information on the lower atmospheric context and the surface parameters. Nevertheless, atmospheric scattering and absorption need to be clearly evaluated before we can extract the surface properties. In various studies (Solomonidou et al., 2014; 2016; 2018; 2019; 2020a, 2020b; Lopes et al., 2016; Malaska et al., 2016; 2020), we used radiative transfer modeling in order to evaluate the atmospheric scattering and absorption and securely extract the surface albedo of multiple Titan areas including the major geomorphological units. We also investigated the morphological and microwave characteristics of these features using Cassini RADAR data in their SAR and radiometry mode. Here, we present a global map for Titan’s surface showing the chemical composition constraints for the various units. The results show that Titan’s surface composition, at the depths detected by VIMS, has significant latitudinal dependence, with its equator being dominated by organic materials from the atmosphere and a very dark unknown material, while higher latitudes contain more water ice. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan’s surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.</p> <p>References: [1] Solomonidou, A., et al. (2014), J. Geophys. Res. Planets, 119, 1729; [2] Solomonidou, A., et al. (2016), Icarus, 270, 85; [3] Solomonidou, A., et al. (2018), J. Geophys. Res. Planets, 123, 489; [4] Solomonidou, A., et al. (2020a), Icarus, 344, 113338; [5] Solomonidou, A., et al. (2020b), A&A 641, A16; [6] Lopes, R., et al. (2016) Icarus, 270, 162; [7] Malaska, M., et al. (2016), Icarus 270, 130; [8] Malaska, M., et al. (2020), Icarus, 344, 113764.</p> <p>Acknowledgements: This work was conducted at the California Institute of Technology (Caltech) under contract with NASA. Y.M. and A.S. (partly) was  supported by the Czech Science Foundation (grant no. 20-27624Y). ©2021 California Institute of Technology. Government sponsorship acknowledged.</p>

scholarly journals The chemical composition of impact craters on Titan

2020 ◽  
Author(s):  
Anezina Solomonidou ◽  
Catherine Neish ◽  
Athena Coustenis ◽  
Michael Malaska ◽  
Alice Le Gall ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Radiative Transfer ◽  
Organic Material ◽  
Impact Crater ◽  
Surface Composition ◽  
Impact Craters ◽  
Spectral Features ◽  
Water Ice ◽  
Dark Material ◽  
The Impact

<p>We investigate the spectral behavior of nine Titan impact craters in order to constrain their surface composition using Visual and Infrared Mapping Spectrometer (VIMS) data and a radiative transfer code (RT) [e.g. 1] in addition to emissivity data. Past studies have looked at the chemical composition of impact craters either by using qualitative comparisons between craters [e.g. 2;3] or by combining all craters into a single unit [4], rather than separating them by geographic location or degradation state. Here, we use a radiative transfer model to first estimate the atmospheric contribution to the data, then extract the surface albedos of the impact crater subunits, and finally constrain their surface composition by using a library of candidate Titan materials. Following the general characterization of the impact craters, we study two impact crater subunits, the ‘crater floor’ and the ‘ejecta blanket’. The results show that Titan’s mid-latitude plain craters: Afekan, Soi, and Forseti, in addition to Sinlap and Menrva are enriched in an OH-bearing constituent (likely water-ice) in an organic based mixture, while the equatorial dune craters: Selk, Ksa, Guabonito, and Santorini, appear to be purely composed of organic material (mainly unknown dune dark material). This follows the pattern seen in [4], where midlatitude alluvial fans, undifferentiated plains, and labyrinths have surface spectra consistent with a mixture of tholin-like spectral features and water ice-like spectral features, while the equatorial undifferentiated plains, hummocky terrains, dunes, and variable plains appear to have spectra similar to a dark material and tholin-like mixture in their very top layers. These observations also agree with the evolution scenario proposed by [3] wherein the impact cratering process produces a mixture of organic material and water-ice, which is later “cleaned” through fluvial erosion in the midlatitude plains. This cleaning process does not appear to operate in the equatorial dunes, which seem to be quickly covered by a thin layer of sand sediment (with the exception of the freshest crater on Titan, Sinlap). Thus, it appears that active processes are working to shape the surface of Titan, and it remains a dynamic world in the present day.</p> <p>[1] Hirtzig, M., et al. (2013). Icarus, 226, 470–486; [2] Neish, C.D., et al. (2015), Geophys. Res. Lett. 42, 3746–3754; [3] Werynski, A., et al. (2019), Icarus, 321, 508-521; [4] Solomonidou, A., et al. (2018), J. Geophys. Res, 123, 2, 489-507</p>

Rapidly Solidified Melt-spun Bi-Sn Ribbons: Surface Composition Issues

2016 ◽  
pp. 3287-3297
Author(s):  
Tarek El Ashram ◽  
Ana P. Carapeto ◽  
Ana M. Botelho do Rego
Keyword(s):  
Chemical Composition ◽  
Optical Microscopy ◽  
Melt Spinning ◽  
Surface Composition ◽  
Electrochemical Process ◽  
Melt Spun ◽  
Bismuth Alloy ◽  
The One ◽  
Rapidly Solidified ◽  
Melt Spinning Technique

Tin-bismuth alloy ribbons were produced using melt-spinning technique. The two main surfaces (in contact with the rotating wheel and exposed to the air) were characterized with Optical Microscopy and AFM, revealing that the surface exposed to the air is duller (due to a long-range heterogeneity) than the opposite surface. Also the XPS chemical composition revealed many differences between them both on the corrosion extension and on the total relative amounts of tin and bismuth. For instance, for the specific case of an alloy with a composition Bi-4 wt % Sn, the XPS atomic ratios Sn/Bi are 1.1 and 3.7 for the surface in contact with the rotating wheel and for the one exposed to air, respectively, showing, additionally, that a large segregation of tin at the surface exists (nominal ratio should be 0.073). This segregation was interpreted as the result of the electrochemical process yielding the corrosion products.

scholarly journals The composition of Europa's near-surface atmosphere

2008 ◽  
Vol 4 (S251) ◽  
pp. 327-328
Author(s):  
Mau C. Wong ◽  
Tim Cassidy ◽  
Robert E. Johnson
Keyword(s):  
Solar System ◽  
Surface Composition ◽  
Near Surface ◽  
Water Ice ◽  
Model Studies ◽  
Surface Atmosphere ◽  
Jovian Magnetosphere ◽  
Ice Surface ◽  
Geophysical Phenomenon ◽  
Inorganic Species

AbstractThe presence of an undersurface ocean renders Europa as one of the few planetary bodies in our Solar System that has been conjectured to have possibly harbored life. Some of the organic and inorganic species present in the ocean underneath are expected to transport upwards through the relatively thin ice crust and manifest themselves as impurities of the water ice surface. For this reason, together with its unique dynamic atmosphere and geological features, Europa has attracted strong scientific interests in past decades.Europa is imbedded inside the Jovian magnetosphere, and, therefore, is constantly subjected to the immerse surrounding radiations, similar to the other three Galilean satellites. The magnetosphere-atmosphere-surface interactions form a complex system that provides a multitude of interesting geophysical phenomenon that is unique in the Solar System. The atmosphere of Europa is thought to have created by, mostly, charged particles sputtering of surface materials. Consequently, the study of Europa's atmosphere can be used as a tool to infer the surface composition. In this paper, we will discuss our recent model studies of Europa's near-surface atmosphere. In particular, the abundances and distributions of the dominant O2 and H2O species, and of other organic and inorganic minor species will be addressed.

scholarly journals Rationale for BepiColombo Studies of Mercury’s Surface and Composition

2020 ◽  
Vol 216 (4) ◽  
Author(s):  
David A. Rothery ◽  
Matteo Massironi ◽  
Giulia Alemanno ◽  
Océane Barraud ◽  
Sebastien Besse ◽  
...  
Keyword(s):  
Heliocentric Distance ◽  
Topographic Mapping ◽  
Space Weathering ◽  
Volatile Species ◽  
Origin And Evolution ◽  
Geological Processes ◽  
Physical Chemical ◽  
Crustal Origin ◽  
Northern And Southern Hemispheres

Abstract BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury’s surface than the suite carried by NASA’s MESSENGER spacecraft. Moreover, BepiColombo’s data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER’s remarkable achievements. Furthermore, the geometry of BepiColombo’s orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping. We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury’s surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER’s more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution. We anticipate that the insights gained into Mercury’s geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury’s origin including the nature and original heliocentric distance of the material from which it formed.

scholarly journals Amorphous Silica and Carbon-rich nanotemplated surfaces as model interstellar dust surfaces for laboratory astrochemistry

2015 ◽  
Vol 11 (A29A) ◽  
Author(s):  
Natalia Pascual ◽  
A. Dawes ◽  
F. Gonz'alez-Posada ◽  
D. Chakarov ◽  
N. Thompson ◽  
...  
Keyword(s):  
Amorphous Silica ◽  
Interstellar Dust ◽  
Surface Composition ◽  
Laboratory Studies ◽  
Water Ice ◽  
Composition Effects ◽  
Dust Surface

AbstractTraditional laboratory studies on dust-ice systems have proved how the nature of the dust surface significantly affects ice structure and reactivity. Although the surface composition effects have been widely studied recently, no attention has been paid to the dust sizes. We show how dust the grains size and topography, as well as their composition, affects their interaction with light and the morphology of water ice mantles on top of them.

scholarly journals Comparative study of water ice exposures on cometary nuclei using multispectral imaging data

2016 ◽  
Vol 462 (Suppl 1) ◽  
pp. S394-S414 ◽  
Author(s):  
N. Oklay ◽  
J. M. Sunshine ◽  
M. Pajola ◽  
A. Pommerol ◽  
J.-B. Vincent ◽  
...  
Keyword(s):  
Comparative Study ◽  
Multispectral Imaging ◽  
Imaging Data ◽  
Cometary Nuclei ◽  
Water Ice

scholarly journals Martian Surface Composition as Determined by the MGS Thermal Emission Spectrometer

2002 ◽  
Vol 12 ◽  
pp. 636
Author(s):  
Steve R. Ruff ◽  
Philip R. Christensen ◽  
Joshua L. Bandfield ◽  
Victoria E. Hamilton ◽  
Hugh H. Kieffer ◽  
...  
Keyword(s):  
Large Scale ◽  
Thermal Emission ◽  
Surface Composition ◽  
Martian Surface ◽  
Hydrothermal Conditions ◽  
Plagioclase Feldspar ◽  
Water Ice ◽  
Sheet Silicates ◽  
Aram Chaos ◽  
Sinus Meridiani

AbstractThe surface composition of Mars has been investigated using the Thermal Emission Spectrometer (TES) instrument during the mapping phase of the Mars Global Surveyor mission. The TES has mapped ~85% of the Martian surface at a resolution of 3-9 km. Separation of the atmospheric dust, water-ice cloud, CO2, water vapor, and surface components has been accomplished using radiative transfer and deconvolution. Two distinct surface compositional units have been mapped; (1) a basalt with plagioclase feldspar, Ca-rich pyroxene, minor sheet silicates; and (2) a basaltic andesite with silica glass, plagioclase, and minor pyroxene. Three large-scale (100’s km) accumulations of hematite have been found in Sinus Meridiani, Aram Chaos and Ophir/Candor Chasms. These regions are interpreted to be formed by aqueous precipitation under either ambient or hydrothermal conditions. No surfaces with detectable abundances of carbonate have been found. The albedo of the surface has been mapped with an absolute accuracy of ~1-2% and significant changes in surface albedo have occurred from the orbital measurements obtained by the Viking IRTM instrument.

scholarly journals Spectral stratigraphy and clay minerals analysis in parts of Hellas Planitia, Mars

2014 ◽  
Vol XL-8 ◽  
pp. 419-422
Author(s):  
I. C. Das ◽  
J. Joseph ◽  
S. K. Subramanian ◽  
V. K. Dadhwal
Keyword(s):  
Chemical Composition ◽  
Clay Minerals ◽  
Absorption Feature ◽  
Crater Wall ◽  
Spectral Variability ◽  
Origin And Evolution ◽  
Different Types ◽  
Surface Alteration ◽  
Alteration Minerals ◽  
Absorption Features

Absorption features that occur in reflectance spectra are a sensitive indicator of mineralogy and chemical composition for a wide variety of materials. The investigation of the mineralogy and chemical composition of surfaces give information about the origin and evolution of planetary bodies. On Mars, the processes of formation of different types of clay minerals result from different types of wet conditions viz. hydrothermalism, subsurface/groundwater weathering, surface alteration etc. The image analyzed in the present study was frt000947f- 164-trr3 (−27.87N–65.06E). Through the spectral stratigraphic characterization along a crater wall, eight (8) different layers were identified considering the spectral variability and their position. In Hellas Planitia, the alteration minerals identified by CRISM based on distinctive absorptions from 0.4 to3.9 μm include Al-rich smectite, montmorillonite, phyllosilicate mineral at 2.2 μm and 2.35 μm, including strong absorption feature noticed at 1.9 μm. We conclude that the layers exposed in the crater wall help characterize the compositional stratigraphy for confirming the presence of hydrated minerals in this region as an outcome of geohydrological weathering process.

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