Roger N Clark (Former Employee)
Science and Products
Filter Total Items: 71
SPVIEW; spectral plot program for accessing the USGS Digital Spectral Library database with MS-DOS personal computers, version 1.00
No abstract available
Authors
K.E. Livo, Roger N. Clark, Daniel H. Knepper
SPECtrum Processing Routines User's Manual Version 3 (program SPECPR)
IntroductionThe SPECtrum Processing Routines (SPECPR) is a large-scale interactive program for general one-dimensional array processing and optimized for reflectance spectroscopy data and analysis. The program processes one-dimensional arrays up to 4852 data points and the operations include addition, subtraction, multiplication, division, trigonometric functions, logarithmic and exponential funct
Authors
Roger N. Clark
Evidence for ammonium-bearing minerals on Ceres
Spectra obtained from recent telescopic observation of 1-Ceres and laboratory measurements and theoretical calculations of three component mixtures of Ceres analog material suggest that an ammoniated phyllosilicate is present on the surface of the asteroid, rather than H2O frost as had been previously reported. The presence of an ammoniated phyllosilicate, most likely ammoniated saponite, on the s
Authors
Trude V. V. King, Roger N. Clark, W. M. Calvin, David M. Sherman, R. H. Brown
Modeling the reflectance spectrum of Callisto 0.25 to 4.1μm
The reflectance spectrum of Callisto from 0.2 to 4.1 μm is modeled using a simultaneous intimate plus areal mixture solution of ice and dark material which satisfies absorption band depths and reflectance levels. The model uses the radiative transfer theory based on Hapke's (1981, J. Geophys. Res. 86, 3039–3054) work, optical constants of materials and includes effects of grain size and abundance
Authors
Wendy M. Calvin, Roger N. Clark
Infrared spectra and crystal chemistry of scapolites: implications for Martian mineralogy
Near‐infrared and midinfrared spectra of a wide range of scapolite compositions were studied to determine the cause of the 2.36‐μm features that have been correlated with similar features in the near‐IR spectrum of Mars. We attribute the 2.36−μm features to vibrations caused by HCO3− and HSO4− in the anion sites of scapolite. The 2.36‐μm absorption complex consists of four overlapping bands with t
Authors
Gregg A. Swayze, Roger N. Clark
High-resolution reflectance spectra of Mars in the 2.3-μm region: evidence for the mineral scapolite
patially resolved reflectance spectra of Mars in the 2.2- to 2.4-μm spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of overlapping narrow features, but in many locations, such as Hellas, Chryse, Ede
Authors
Roger N. Clark, Gregg A. Swayze, Robert B. Singer, James B. Pollack
Spectral characteristics of chlorites and Mg‐serpentines using high‐resolution reflectance spectroscopy
The present laboratory study using high‐resolution reflectance spectroscopy (0.25–2.7 μm) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end‐members of the Mg‐rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a function of Fe/
Authors
T. V. V. King, Roger N. Clark
Search for volatiles on icy satellites: I. Europa
New reflectance spectra have been obtained for both the leading and trailing sides of Europa, using the Cooled Grating Array Spectrometer (CGAS) of the NASA Infrared Telescope Facility (IRTF). The spectra are of higher precision than any yet obtained. Spectra of Europa's trailing side (central meridian longitude ≈300°) obtained in 1985 show two weak absorptions near 2.2 and 2.3 μm. Both of these f
Authors
R. H. Brown, D. P. Cruikshank, A. T. Tokunaga, R. G. Smith, Roger N. Clark
Europa: Characterization and interpretation of global spectral surface units
The Voyager global multispectral mosaic of the Galilean satellite Europa (T. V. Johnson, L. A. Soderblom, J. A. Mosher, G. E. Danielson, A. F. Cook, and P. Kupferman, 1983, J. Geophys. Res. 88, 5789–5805) was analyzed to map surface units with similar optical properties (T. B. McCord, M. L. Nelson, R. N. Clark, A. Meloy, W. Harrison, T. V. Johnson, D. L. Matson, J. A. Mosher, and L. Soderblom, 198
Authors
M. L. Nelson, T. B. McCord, Roger N. Clark, T. V. Johnson, D. L. Matson, J. A. Mosher, Laurence A. Soderblom
Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications
Several methods for the analysis of remotely sensed reflectance data are compared, including empirical methods and scattering theories, both of which are important for solving remote sensing problems. The concept of the photon mean optical path length and the implications for use in modeling reflectance spectra are presented. It is shown that the mean optical path length in a particulate surface i
Authors
Roger N. Clark, T. L. Roush
Spectral properties of ice‐particulate mixtures and implications for remote sensing: 1. Intimate mixtures
The spectral properties of water ice‐particulate mixtures are studied for the purpose of deriving the ice and particulate abundances from remotely obtained spectra (particulates referring to nonicy materials in the form of grains). Reflectance levels and ice absorption band depths are a complex function of the single scattering albedo of the particulates embedded in the ice. The ice absorption ban
Authors
Roger N. Clark, Paul G. Lucey
Science and Products
Filter Total Items: 71
SPVIEW; spectral plot program for accessing the USGS Digital Spectral Library database with MS-DOS personal computers, version 1.00
No abstract available
Authors
K.E. Livo, Roger N. Clark, Daniel H. Knepper
SPECtrum Processing Routines User's Manual Version 3 (program SPECPR)
IntroductionThe SPECtrum Processing Routines (SPECPR) is a large-scale interactive program for general one-dimensional array processing and optimized for reflectance spectroscopy data and analysis. The program processes one-dimensional arrays up to 4852 data points and the operations include addition, subtraction, multiplication, division, trigonometric functions, logarithmic and exponential funct
Authors
Roger N. Clark
Evidence for ammonium-bearing minerals on Ceres
Spectra obtained from recent telescopic observation of 1-Ceres and laboratory measurements and theoretical calculations of three component mixtures of Ceres analog material suggest that an ammoniated phyllosilicate is present on the surface of the asteroid, rather than H2O frost as had been previously reported. The presence of an ammoniated phyllosilicate, most likely ammoniated saponite, on the s
Authors
Trude V. V. King, Roger N. Clark, W. M. Calvin, David M. Sherman, R. H. Brown
Modeling the reflectance spectrum of Callisto 0.25 to 4.1μm
The reflectance spectrum of Callisto from 0.2 to 4.1 μm is modeled using a simultaneous intimate plus areal mixture solution of ice and dark material which satisfies absorption band depths and reflectance levels. The model uses the radiative transfer theory based on Hapke's (1981, J. Geophys. Res. 86, 3039–3054) work, optical constants of materials and includes effects of grain size and abundance
Authors
Wendy M. Calvin, Roger N. Clark
Infrared spectra and crystal chemistry of scapolites: implications for Martian mineralogy
Near‐infrared and midinfrared spectra of a wide range of scapolite compositions were studied to determine the cause of the 2.36‐μm features that have been correlated with similar features in the near‐IR spectrum of Mars. We attribute the 2.36−μm features to vibrations caused by HCO3− and HSO4− in the anion sites of scapolite. The 2.36‐μm absorption complex consists of four overlapping bands with t
Authors
Gregg A. Swayze, Roger N. Clark
High-resolution reflectance spectra of Mars in the 2.3-μm region: evidence for the mineral scapolite
patially resolved reflectance spectra of Mars in the 2.2- to 2.4-μm spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of overlapping narrow features, but in many locations, such as Hellas, Chryse, Ede
Authors
Roger N. Clark, Gregg A. Swayze, Robert B. Singer, James B. Pollack
Spectral characteristics of chlorites and Mg‐serpentines using high‐resolution reflectance spectroscopy
The present laboratory study using high‐resolution reflectance spectroscopy (0.25–2.7 μm) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end‐members of the Mg‐rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a function of Fe/
Authors
T. V. V. King, Roger N. Clark
Search for volatiles on icy satellites: I. Europa
New reflectance spectra have been obtained for both the leading and trailing sides of Europa, using the Cooled Grating Array Spectrometer (CGAS) of the NASA Infrared Telescope Facility (IRTF). The spectra are of higher precision than any yet obtained. Spectra of Europa's trailing side (central meridian longitude ≈300°) obtained in 1985 show two weak absorptions near 2.2 and 2.3 μm. Both of these f
Authors
R. H. Brown, D. P. Cruikshank, A. T. Tokunaga, R. G. Smith, Roger N. Clark
Europa: Characterization and interpretation of global spectral surface units
The Voyager global multispectral mosaic of the Galilean satellite Europa (T. V. Johnson, L. A. Soderblom, J. A. Mosher, G. E. Danielson, A. F. Cook, and P. Kupferman, 1983, J. Geophys. Res. 88, 5789–5805) was analyzed to map surface units with similar optical properties (T. B. McCord, M. L. Nelson, R. N. Clark, A. Meloy, W. Harrison, T. V. Johnson, D. L. Matson, J. A. Mosher, and L. Soderblom, 198
Authors
M. L. Nelson, T. B. McCord, Roger N. Clark, T. V. Johnson, D. L. Matson, J. A. Mosher, Laurence A. Soderblom
Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications
Several methods for the analysis of remotely sensed reflectance data are compared, including empirical methods and scattering theories, both of which are important for solving remote sensing problems. The concept of the photon mean optical path length and the implications for use in modeling reflectance spectra are presented. It is shown that the mean optical path length in a particulate surface i
Authors
Roger N. Clark, T. L. Roush
Spectral properties of ice‐particulate mixtures and implications for remote sensing: 1. Intimate mixtures
The spectral properties of water ice‐particulate mixtures are studied for the purpose of deriving the ice and particulate abundances from remotely obtained spectra (particulates referring to nonicy materials in the form of grains). Reflectance levels and ice absorption band depths are a complex function of the single scattering albedo of the particulates embedded in the ice. The ice absorption ban
Authors
Roger N. Clark, Paul G. Lucey