Todd Hoefen
Todd Hoefen is a Geophysicist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 109
Compositional mapping of Saturn's satellite Dione with Cassini VIMS and implications of dark material in the Saturn system
Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Dione provided key information for solving the riddle of the origin of the dark material in the Saturn system. The Dione VIMS data show a pattern of bombardment of fine, sub-0.5-??m diameter particles impacting the satellite from the trailing side direction. Multiple line
Authors
R. N. Clark, J. M. Curchin, R. Jaumann, D. P. Cruikshank, R. H. Brown, T.M. Hoefen, K. Stephan, Johnnie N. Moore, B. J. Buratti, K. H. Baines, P. D. Nicholson, R.M. Nelson
Preliminary analytical results for ash and burned soils from the October 2007 southern California wildfires
The U.S. Geological Survey (USGS) collected ash and burned soils from about 28 sites in southern California wildfire areas (Harris, Witch, Ammo, Santiago, Canyon and Grass Valley) from Nov. 2 through 9, 2007 (table 1). USGS researchers are applying a wide variety of analytical methods to these samples, with the goal of helping identify characteristics of the ash and soils from wildland and suburba
Authors
Geoffrey S. Plumlee, Deborah A. Martin, Todd Hoefen, Raymond F. Kokaly, Philip Hageman, Alison Eckberg, Gregory P. Meeker, Monique Adams, Michael Anthony, Paul J. Lamothe
USGS Digital Spectral Library splib06a
Introduction
We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra coll
Authors
Roger N. Clark, Gregg A. Swayze, Richard A. Wise, K. Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Stephen J. Sutley
Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust: Asbestos content of the settled dust
On September 17 and 18, 2001, samples of settled dust and airfall debris were collected from 34 sites within a 1-km radius of the WTC collapse site, including a sample from an indoor location unaffected by rainfall, and samples of insulation from two steel beams at Ground Zero. Laboratory spectral and x-ray diffraction analyses of the field samples detected trace levels of serpentine minerals, inc
Authors
Gregg A. Swayze, Roger N. Clark, Stephen J. Sutley, Todd M. Hoefen, Geoffrey S. Plumlee, Gregory P. Meeker, Isabelle Brownfield, Keith E. Livo, Laurie C. Morath
Evaluating minerals of environmental concern using spectroscopy
Imaging spectroscopy has been successfully used to aid researchers in characterizing potential environmental impacts posed by acid-rock drainage, ore-processing dust on mangroves, and asbestos in serpentine mineral deposits and urban dust. Many of these applications synergistically combine field spectroscopy with remote sensing data, thus allowing more-precise data calibration, spectral analysis o
Authors
G.A. Swayze, R. N. Clark, C.T. Higgins, R.F. Kokaly, K. Eric Livo, T.M. Hoefen, C. Ong, F.A. Kruse
Compositional maps of Saturn's moon Phoebe from imaging spectroscopy
The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-neb
Authors
R. N. Clark, R. H. Brown, R. Jaumann, D. P. Cruikshank, R.M. Nelson, B. J. Buratti, T. B. McCord, J. Lunine, K. H. Baines, G. Bellucci, J.-P. Bibring, F. Capaccioni, P. Cerroni, A. Coradini, V. Formisano, Y. Langevin, D. L. Matson, V. Mennella, P. D. Nicholson, B. Sicardy, Christophe Sotin, T.M. Hoefen, J. M. Curchin, G. Hansen, K. Hibbits, K.-D. Matz
Reflectance spectroscopy as a rapid assessment tool for the detection of amphiboles from the Libby, Montana region
No abstract available.
Authors
Roger N. Clark, Todd M. Hoefen, Gregg A. Swayze, K. Eric Livo, Greg P. Meeker, Steve J. Sutley, Steve Wilson, Isabelle K. Brownfield, J. Sam Vance
Discovery of Olivine in the Nili Fossae Region of Mars
We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface e
Authors
T.M. Hoefen, R. N. Clark, J. L. Bandfield, M. D. Smith, J.C. Pearl, P. R. Christensen
The composition and morphology of amphiboles from the Rainy Creek complex, near Libby, Montana
Thirty samples of amphibole-rich rock from the largest mined vermiculite deposit in the world in the Rainy Creek alkaline-ultramafic complex near Libby, Montana, were collected and analyzed. The amphibole-rich rock is the suspected cause of an abnormally high number of asbestos-related diseases reported in the residents of Libby, and in former mine and mill workers. The amphibole-rich samples were
Authors
G.P. Meeker, A.M. Bern, I. K. Brownfield, H.A. Lowers, S. J. Sutley, T.M. Hoefen, J.S. Vance
USGS Digital Spectral Library splib05a
We have assembled a digital reflectance spectral library of spectra that covers wavelengths from the ultraviolet to near-infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, vegetation, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purp
Authors
Roger N. Clark, Gregg A. Swayze, Richard K. Wise, Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Steve J. Sutley
Environmental studies of the World Trade Center area after the September 11, 2001 attack
This web site describes the results of an interdisciplinary environmental characterization of the World Trade Center (WTC) area after September 11, 2001.Information presented in this site was first made available to the World Trade Center emergency response teams on September 18, 2001 (Thermal hot spot information), and September 27, 2001 (maps and compositional results).The Airborne Visible / Inf
Authors
Roger N. Clark, Robert O. Green, Gregg A. Swayze, Greg Meeker, Steve Sutley, Todd M. Hoefen, K. Eric Livo, Geoff Plumlee, Betina Pavri, Chuck Sarture, Steve Wilson, Phil Hageman, Paul Lamothe, J. Sam Vance, Joe Boardman, Isabelle Brownfield, Carol Gent, Laurie C. Morath, Joseph Taggart, Peter M. Theodorakos, Monique Adams
Images of the World Trade Center site show thermal hot spots on September 16 and 23, 2001
No abstract available.
Authors
Roger N. Clark, Robert O. Green, Gregg A. Swayze, Todd M. Hoefen, K. Eric Livo, Betina Pavi, Chuck Sarcher, Joe Boardman, J. Sam Vance
Science and Products
Filter Total Items: 109
Compositional mapping of Saturn's satellite Dione with Cassini VIMS and implications of dark material in the Saturn system
Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Dione provided key information for solving the riddle of the origin of the dark material in the Saturn system. The Dione VIMS data show a pattern of bombardment of fine, sub-0.5-??m diameter particles impacting the satellite from the trailing side direction. Multiple line
Authors
R. N. Clark, J. M. Curchin, R. Jaumann, D. P. Cruikshank, R. H. Brown, T.M. Hoefen, K. Stephan, Johnnie N. Moore, B. J. Buratti, K. H. Baines, P. D. Nicholson, R.M. Nelson
Preliminary analytical results for ash and burned soils from the October 2007 southern California wildfires
The U.S. Geological Survey (USGS) collected ash and burned soils from about 28 sites in southern California wildfire areas (Harris, Witch, Ammo, Santiago, Canyon and Grass Valley) from Nov. 2 through 9, 2007 (table 1). USGS researchers are applying a wide variety of analytical methods to these samples, with the goal of helping identify characteristics of the ash and soils from wildland and suburba
Authors
Geoffrey S. Plumlee, Deborah A. Martin, Todd Hoefen, Raymond F. Kokaly, Philip Hageman, Alison Eckberg, Gregory P. Meeker, Monique Adams, Michael Anthony, Paul J. Lamothe
USGS Digital Spectral Library splib06a
Introduction
We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra coll
Authors
Roger N. Clark, Gregg A. Swayze, Richard A. Wise, K. Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Stephen J. Sutley
Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust: Asbestos content of the settled dust
On September 17 and 18, 2001, samples of settled dust and airfall debris were collected from 34 sites within a 1-km radius of the WTC collapse site, including a sample from an indoor location unaffected by rainfall, and samples of insulation from two steel beams at Ground Zero. Laboratory spectral and x-ray diffraction analyses of the field samples detected trace levels of serpentine minerals, inc
Authors
Gregg A. Swayze, Roger N. Clark, Stephen J. Sutley, Todd M. Hoefen, Geoffrey S. Plumlee, Gregory P. Meeker, Isabelle Brownfield, Keith E. Livo, Laurie C. Morath
Evaluating minerals of environmental concern using spectroscopy
Imaging spectroscopy has been successfully used to aid researchers in characterizing potential environmental impacts posed by acid-rock drainage, ore-processing dust on mangroves, and asbestos in serpentine mineral deposits and urban dust. Many of these applications synergistically combine field spectroscopy with remote sensing data, thus allowing more-precise data calibration, spectral analysis o
Authors
G.A. Swayze, R. N. Clark, C.T. Higgins, R.F. Kokaly, K. Eric Livo, T.M. Hoefen, C. Ong, F.A. Kruse
Compositional maps of Saturn's moon Phoebe from imaging spectroscopy
The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-neb
Authors
R. N. Clark, R. H. Brown, R. Jaumann, D. P. Cruikshank, R.M. Nelson, B. J. Buratti, T. B. McCord, J. Lunine, K. H. Baines, G. Bellucci, J.-P. Bibring, F. Capaccioni, P. Cerroni, A. Coradini, V. Formisano, Y. Langevin, D. L. Matson, V. Mennella, P. D. Nicholson, B. Sicardy, Christophe Sotin, T.M. Hoefen, J. M. Curchin, G. Hansen, K. Hibbits, K.-D. Matz
Reflectance spectroscopy as a rapid assessment tool for the detection of amphiboles from the Libby, Montana region
No abstract available.
Authors
Roger N. Clark, Todd M. Hoefen, Gregg A. Swayze, K. Eric Livo, Greg P. Meeker, Steve J. Sutley, Steve Wilson, Isabelle K. Brownfield, J. Sam Vance
Discovery of Olivine in the Nili Fossae Region of Mars
We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface e
Authors
T.M. Hoefen, R. N. Clark, J. L. Bandfield, M. D. Smith, J.C. Pearl, P. R. Christensen
The composition and morphology of amphiboles from the Rainy Creek complex, near Libby, Montana
Thirty samples of amphibole-rich rock from the largest mined vermiculite deposit in the world in the Rainy Creek alkaline-ultramafic complex near Libby, Montana, were collected and analyzed. The amphibole-rich rock is the suspected cause of an abnormally high number of asbestos-related diseases reported in the residents of Libby, and in former mine and mill workers. The amphibole-rich samples were
Authors
G.P. Meeker, A.M. Bern, I. K. Brownfield, H.A. Lowers, S. J. Sutley, T.M. Hoefen, J.S. Vance
USGS Digital Spectral Library splib05a
We have assembled a digital reflectance spectral library of spectra that covers wavelengths from the ultraviolet to near-infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, vegetation, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purp
Authors
Roger N. Clark, Gregg A. Swayze, Richard K. Wise, Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Steve J. Sutley
Environmental studies of the World Trade Center area after the September 11, 2001 attack
This web site describes the results of an interdisciplinary environmental characterization of the World Trade Center (WTC) area after September 11, 2001.Information presented in this site was first made available to the World Trade Center emergency response teams on September 18, 2001 (Thermal hot spot information), and September 27, 2001 (maps and compositional results).The Airborne Visible / Inf
Authors
Roger N. Clark, Robert O. Green, Gregg A. Swayze, Greg Meeker, Steve Sutley, Todd M. Hoefen, K. Eric Livo, Geoff Plumlee, Betina Pavri, Chuck Sarture, Steve Wilson, Phil Hageman, Paul Lamothe, J. Sam Vance, Joe Boardman, Isabelle Brownfield, Carol Gent, Laurie C. Morath, Joseph Taggart, Peter M. Theodorakos, Monique Adams
Images of the World Trade Center site show thermal hot spots on September 16 and 23, 2001
No abstract available.
Authors
Roger N. Clark, Robert O. Green, Gregg A. Swayze, Todd M. Hoefen, K. Eric Livo, Betina Pavi, Chuck Sarcher, Joe Boardman, J. Sam Vance