Todd Hoefen
Todd Hoefen is a Geophysicist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 112
Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust: Asbestos content of the settled dust 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...
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 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...
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 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...
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 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
USGS Digital Spectral Library splib05a 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...
Authors
Roger N. Clark, Gregg A. Swayze, Richard K. Wise, Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Steve J. Sutley
Discovery of Olivine in the Nili Fossae Region of Mars 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...
Authors
T.M. Hoefen, R. N. Clark, J. L. Bandfield, M. D. Smith, J.C. Pearl, P. R. Christensen
Science and Products
Filter Total Items: 112
Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust: Asbestos content of the settled dust 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...
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 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...
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 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...
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 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
USGS Digital Spectral Library splib05a 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...
Authors
Roger N. Clark, Gregg A. Swayze, Richard K. Wise, Eric Livo, Todd M. Hoefen, Raymond F. Kokaly, Steve J. Sutley
Discovery of Olivine in the Nili Fossae Region of Mars 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...
Authors
T.M. Hoefen, R. N. Clark, J. L. Bandfield, M. D. Smith, J.C. Pearl, P. R. Christensen