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Publications

Filter Total Items: 335

Organic sedimentary deposits in Titan's dry lakebeds: Probable evaporite

We report the discovery of organic sedimentary deposits at the bottom of dry lakebeds near Titan’s north pole in observations from the Cassini Visual and Infrared Mapping Spectrometer (VIMS). We show evidence that the deposits are evaporitic, making Titan just the third known planetary body with evaporitic processes after Earth and Mars, and is the first that uses a solvent other than water.
Authors
J. W. Barnes, J. Bow, J. Schwartz, R. H. Brown, J.M. Soderblom, A. G. Hayes, G. Vixie, S. Le Mouelic, S. Rodriguez, Christophe Sotin, R. Jaumann, K. Stephan, L. A. Soderblom, Roger N. Clark, B. J. Buratti, K. H. Baines, P. D. Nicholson

Titan's cloud seasonal activity from winter to spring with Cassini/VIMS

Since Saturn orbital insertion in July 2004, the Cassini orbiter has been observing Titan throughout most of the northern winter season (October 2002–August 2009) and the beginning of spring, allowing a detailed monitoring of Titan’s cloud coverage at high spatial resolution with close flybys on a monthly basis. This study reports on the analysis of all the near-infrared images of Titan’s clouds a
Authors
S. Rodriguez, S. Le Mouelic, P. Rannou, Christophe Sotin, R. H. Brown, J. W. Barnes, C.A. Griffith, J. Burgalat, K. H. Baines, B. J. Buratti, R. N. Clark, P. D. Nicholson

Compositional diversity and geologic insights of the Aristarchus crater from Moon Mineralogy Mapper data

The Moon Mineralogy Mapper (M3) acquired high spatial and spectral resolution data of the Aristarchus Plateau with 140 m/pixel in 85 spectral bands from 0.43 to 3.0 m. The data were collected as radiance and converted to reflectance using the observational constraints and a solar spectrum scaled to the Moon-Sun distance. Summary spectral parameters for the area of mafic silicate 1 and 2 m bands we
Authors
J.F. Mustard, C.M. Pieters, P.J. Isaacson, J.W. Head, S. Besse, R. N. Clark, R.L. Klima, N.E. Petro, M.I. Staid, J.M. Sunshine, C.J. Runyon, S. Tompkins

Remote compositional analysis of lunar olivine-rich lithologies with Moon Mineralogy Mapper (M3) spectra

A systematic approach for deconvolving remotely sensed lunar olivine‐rich visible to near‐infrared (VNIR) reflectance spectra with the Modified Gaussian Model (MGM) is evaluated with Chandrayaan‐1 Moon Mineralogy Mapper (M3) spectra. Whereas earlier studies of laboratory reflectance spectra focused only on complications due to chromite inclusions in lunar olivines, we develop a systematic approach
Authors
P.J. Isaacson, C.M. Pieters, S. Besse, Roger N. Clark, J.W. Head, R.L. Klima, J.F. Mustard, N.E. Petro, M.I. Staid, J.M. Sunshine, L.A. Taylor, K.G. Thaisen, S. Tompkins

The Christiansen Effect in Saturn's narrow dusty rings and the spectral identification of clumps in the F ring

Stellar occultations by Saturn’s rings observed with the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft reveal that dusty features such as the F ring and the ringlets in the Encke and the Laplace Gaps have distinctive infrared transmission spectra. These spectra show a narrow optical depth minimum at wavelengths around 2.87 μm. This minimum is likely due to the Chri
Authors
M.M. Hedman, P. D. Nicholson, M.R. Showalter, R. H. Brown, B. J. Buratti, R. N. Clark, K. Baines, Christophe Sotin

Mg-spinel lithology: A new rock type on the lunar farside

High-resolution compositional data from Moon Mineralogy Mapper (M 3) for the Moscoviense region on the lunar farside reveal three unusual, but distinctive, rock types along the inner basin ring. These are designated "OOS" since they are dominated by high concentrations of orthopyroxene, olivine, and Mg-rich spinel, respectively. The OOS occur as small areas, each a few kilometers in size, that are
Authors
C.M. Pieters, S. Besse, J. Boardman, B. Buratti, L. Cheek, R. N. Clark, J. -P. Combe, D. Dhingra, J.N. Goswami, R.O. Green, J.W. Head, P. Isaacson, R. Klima, G. Kramer, S. Lundeen, E. Malaret, T. McCord, J. Mustard, J. Nettles, N. Petro, C. Runyon, M. Staid, J. Sunshine, L.A. Taylor, K. Thaisen, S. Tompkins, J. Whitten

Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on Mars from phyllosilicate mineral assemblages

The enhanced spatial and spectral resolution provided by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) has led to the discovery of numerous hydrated silicate minerals on Mars, particularly in the ancient, cratered crust comprising the southern highlands. Phases recently identified using visible/near-infrared spectra include: smectite, chl
Authors
Bethany L. Ehlmann, John F Mustard, Roger N. Clark, Gregg A. Swayze, Scott L. Murchie

Sources and physical processes responsible for OH/H2O in the lunar soil as revealed by the Moon Mineralogy Mapper (M3)

Analysis of two absorption features near 3 m in the lunar reflectance spectrum, observed by the orbiting M3 spectrometer and interpreted as being due to OH and H2O, is presented, and the results are used to discuss the processes producing these molecules. This analysis focuses on the dependence of the absorptions on lunar physical properties, including composition, illumination, latitude, and temp
Authors
T. B. McCord, L.A. Taylor, J. -P. Combe, G. Kramer, C.M. Pieters, J.M. Sunshine, R. N. Clark

Lunar mare deposits associated with the Orientale impact basin: New insights into mineralogy, history, mode of emplacement, and relation to Orientale Basin evolution from Moon Mineralogy Mapper (M3) data from Chandrayaan-1

Moon Mineralogy Mapper (M3) image and spectral reflectance data are combined to analyze mare basalt units in and adjacent to the Orientale multiring impact basin. Models are assessed for the relationships between basin formation and mare basalt emplacement. Mare basalt emplacement on the western nearside limb began prior to the Orientale event as evidenced by the presence of cryptomaria. The earli
Authors
J. Whitten, J.W. Head, M. Staid, C.M. Pieters, J. Mustard, R. Clark, J. Nettles, R.L. Klima, L. Taylor

Wave constraints for Titan's Jingpo Lacus and Kraken Mare from VIMS specular reflection lightcurves

Stephan et al. (Stephan, K. et al. [2010]. Geophys. Res. Lett. 37, 7104-+.) first saw the glint of sunlight specularly reflected off of Titan's lakes. We develop a quantitative model for analyzing the photometric lightcurve generated during a flyby in which the specularly reflected light flux depends on the fraction of the solar specular footprint that is covered by liquid. We allow for surface wa
Authors
J. W. Barnes, J.M. Soderblom, R. H. Brown, L. A. Soderblom, K. Stephan, R. Jaumann, Stéphane Le Mouélic, S. Rodriguez, Christophe Sotin, B. J. Buratti, K. H. Baines, R. N. Clark, P. D. Nicholson

The dispersion of fibrous amphiboles by glacial processes in the area surrounding Libby, Montana, USA

Mining operations began at a world-class vermiculite deposit at Vermiculite Mountain near Libby, Montana, circa 1920 and ended in 1990. Fibrous and asbestiform amphiboles intergrown with vermiculite ore are suspected to be a causative factor in an abnormally high number of cases of respiratory diseases in former mine and mill workers, and in residents of Libby. The question addressed in this repor
Authors
William H. Langer, Bradley S. Van Gosen, Gregory P. Meeker, David T. Adams, Todd M. Hoefen

Mapping the distribution of materials in hyperspectral data using the USGS Material Identification and Characterization Algorithm (MICA)

Identifying materials by measuring and analyzing their reflectance spectra has been an important method in analytical chemistry for decades. Airborne and space-based imaging spectrometers allow scientists to detect materials and map their distributions across the landscape. With new satellite-borne hyperspectral sensors planned for the future, for example, HYSPIRI (HYPerspectral InfraRed Imager),

Authors
Raymond F. Kokaly, T. V. V. King, Todd M. Hoefen