Publications
Filter Total Items: 910
Retreat of northern margins of George VI and Wilkins Ice Shelves, Antarctic Peninsula
The George VI and Wilkins Ice Shelves are considered at risk of disintegration due to a regional atmospheric warming trend on the Antarctic Peninsula. Retreat of the northern margin of the George VI Ice Shelf has been observed previously, but the Wilkins Ice Shelf was thought to be stable. We investigated the positions of the northern fronts of these shelves from the literature and looked for chan
Authors
Baerbel K. Lucchitta, Christina E. Rosanova
Overview of the Mars Pathfinder Mission and assessment of landing site predictions
Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000 kilometers in ra
Authors
M. P. Golombek, R. A. Cook, T. Economou, W. M. Folkner, A. F. C. Haldemann, P. H. Kallemeyn, J. M. Knudsen, R. M. Manning, H. J. Moore, T. J. Parker, R. Rieder, J. T. Schofield, P. H. Smith, R. M. Vaughan
Results from the Mars Pathfinder camera
Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the pr
Authors
P. H. Smith, J. F. III Bell, N. T. Bridges, D.T. Britt, Lisa R. Gaddis, R. Greeley, H.U. Keller, Kenneth E. Herkenhoff, R. Jaumann, J. R. Johnson, Randolph L. Kirk, M. Lemmon, J.N. Maki, M.C. Malin, S.L. Murchie, J. Oberst, T. J. Parker, R.J. Reid, R.M. Sablotny, Laurence A. Soderblom, C. Stoker, R. Sullivan, N. Thomas, M.G. Tomasko, W. Ward, E. Wegryn
Glaciological delineation of the dynamic coastline of Antartica
No abstract available.
Authors
Richard S. Williams, Jane G. Ferrigno, Charles Swithinbank, Baerbel K. Lucchitta, Barbara A. Seekins, Christina E. Rosanova
Population analysis of faint galaxies with mixture modeling
We investigate the use of spectral mixture modeling to decompose the integrated spectra of several galaxies. This technique uses a linear combination of template spectra to model over 93% of the variance in Kennicutt's sample of galaxy spectra. One result of our model is a stellar population parameter for each galaxy, which correlates with both star formation rate and the population's mass-to-ligh
Authors
Timothy N. Titus, Earl J. Spillar, Paul Johnson
Radar reflectivities of plausible Titan surfaces
We consider plausible reflectivity ranges for candidate Titan surfaces, with application to radar altimeter investigations on both the Cassini Orbiter and Huygens Probe. The appropriate measure of surface scattering is the specific backscatter cross-section at normal incidence or, for smooth surfaces, the specific backscatter averaged over the sensitivity of the altimeter beam pattern. A clean eth
Authors
Randolph L. Kirk, J. I. Lunine
The imager for Mars Pathfinder experiment
The imager for Mars Pathfinder (IMP), a stereoscopic, multispectral camera, is described in terms of its capabilities for studying the Martian environment. The camera's two eyes, separated by 15.0 cm, provide the camera with range‐finding ability. Each eye illuminates half of a single CCD detector with a field of view of 14.4×14.0° and has 12 selectable filters. The ƒ/18 optics have a large depth
Authors
P. H. Smith, M.G. Tomasko, D. Britt, D.G. Crowe, R. Reid, H.U. Keller, N. Thomas, F. Gliem, P. Rueffer, R. Sullivan, R. Greeley, J. M. Knudsen, M.B. Madsen, H.P. Gunnlaugsson, S.F. Hviid, W. Goetz, Laurence A. Soderblom, L. Gaddis, Randolph L. Kirk
Physiography, Geomorphic/geologic Mapping and Stratigraphy of Venus
No abstract available.
Authors
K. L. Tanaka, D.A. Senske, M. Price, Randolph L. Kirk
The Topography of Asteroid Ida: A Comparison between Photogrammetric and ShapeForm-Shading Image Analysis
We derived high resolution Digital Terrain Models from stereo images of the asteroid Ida that were obtained by the Galileo spacecraft during the flyby in August 1993 and compared these results with terrain models derived from two-dimensional photoclinometry. The comparison shows that there are striking discrepancies between the results from the two models depending on the spatial scale length of s
Authors
Bernd Giese, Juergen Oberst, Randolph L. Kirk, W. Zeitler
Modeling of fluidized ejecta emplacement over digital topography on Venus
The FLOW computer model of McEwen and Malin (1989) modified for application to the study of Venus fluidized ejecta blankets (FEBs) demonstrates that relatively low viscosities, yield strengths, and initial velocities are required to duplicate the observed flow paths of the outflow materials. The model calculates the velocities and simulated flow paths of gravity flows over Magellan topography. The
Authors
Jeffrey R. Johnson, Lisa R. Gaddis
Decomposition of AVIRIS spectra: Extraction of spectral reflectance, atmospheric, and instrumental components
Presents techniques that use only information contained within a raw, high-spectral-resolution, hyperspectral Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scene to estimate and remove additive components (atmospheric scattering and instrument dark current). These techniques allow normalization of multiplicative components (instrument gain, topography, atmospheric transmission) and enhan
Authors
Lisa R. Gaddis, Laurence A. Soderblom, Hugh H. Kieffer, Kris J. Becker, James M. Torson, Kevin F. Mullins
Water on early Mars
Large flood channels, valley networks and a variety of features attributed to the action of ground ice indicate that Mars emerged from heavy bombardment 3.8 Ga ago, with an inventory of water at the surface equivalent to at least a few hundred metres spread over the whole planet, as compared with 3 km for the Earth. The mantle of Mars is much drier than that of the Earth, possibly as a result of g
Authors
Michael D. Carr