Publications
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Does Europa have a subsurface ocean? Evaluation of the geological evidence Does Europa have a subsurface ocean? Evaluation of the geological evidence
It has been proposed that Jupiter's satellite Europa currently possesses a global subsurface ocean of liquid water. Galileo gravity data verify that the satellite is differentiated into an outer H2O layer about 100 km thick but cannot determine the current physical state of this layer (liquid or solid). Here we summarize the geological evidence regarding an extant subsurface ocean...
Authors
Robert T. Pappalardo, Michael J.S. Belton, H.H. Breneman, M. H. Carr, Clark R. Chapman, G.C. Collins, T. Denk, S. Fagents, Paul E. Geissler, B. Giese, R. Greeley, R. Greenberg, J.W. Head, P. Helfenstein, G. Hoppa, S.D. Kadel, K.P. Klaasen, James E. Klemaszewski, K.P. Magee, Alfred S. McEwen, J. M. Moore, W.B. Moore, G. Neukum, C. B. Phillips, L.M. Prockter, G. Schubert, D.A. Senske, R.J. Sullivan, B.R. Tufts, E. P. Turtle, Robert Wagner, K.K. Williams
Observations of Phobos, Deimos, and bright stars with the Imager for Mars Pathfinder Observations of Phobos, Deimos, and bright stars with the Imager for Mars Pathfinder
The Imager for Mars Pathfinder (IMP) was used to observe several objects during the Martian night. The satellites, Phobos and Deimos, were observed on two occasions each, through the IMP geological filters covering the wavelength range 440 nm to 1 μm. The observations were converted to geometric albedo using triaxial ellipsoid models of the satellites and phase functions derived from...
Authors
Nick Thomas, D.T. Britt, Kenneth E. Herkenhoff, Scott L. Murchie, B. Semenov, H.U. Keller, P. H. Smith
Mars Pathfinder spectral measurements of Phobos and Deimos: Comparison with previous data Mars Pathfinder spectral measurements of Phobos and Deimos: Comparison with previous data
The Imager for Mars Pathfinder (IMP) acquired four spectra of parts of the sub‐Mars hemispheres of Phobos and Deimos. The measured region of Phobos is expected to be a mixture of the two spectral units identified on that satellite from Phobos 2 data, and the IMP spectra of Phobos are intermediate to the two units as expected. The derived geometric albedo is consistent with the value for...
Authors
Scott L. Murchie, Nick Thomas, Daniel Britt, Kenneth E. Herkenhoff, James F. Bell
Overview of the Mars Pathfinder Mission: Launch through landing, surface operations, data sets, and science results Overview of the Mars Pathfinder Mission: Launch through landing, surface operations, data sets, and science results
Mars Pathfinder successfully landed at Ares Vallis on July 4, 1997, deployed and navigated a small rover about 100 m clockwise around the lander, and collected data from three science instruments and ten technology experiments. The mission operated for three months and returned 2.3 Gbits of data, including over 16,500 lander and 550 rover images, 16 chemical analyses of rocks and soil...
Authors
M. P. Golombek, R. C. Anderson, J.R. Barnes, J. F. Bell, N. T. Bridges, D.T. Britt, J. Bruckner, R. A. Cook, D. Crisp, J.A. Crisp, T. Economou, W. M. Folkner, R. Greeley, R.M. Haberle, R.B. Hargraves, J.A. Harris, A. F. C. Haldemann, Kenneth E. Herkenhoff, S.F. Hviid, R. Jaumann, J. R. Johnson, P. H. Kallemeyn, H.U. Keller, Randolph L. Kirk, J. M. Knudsen, S. Larsen, M. T. Lemmon, M.B. Madsen, J.A. Magalhaes, J.N. Maki, M.C. Malin, R. M. Manning, J. Matijevic, H.Y. McSween, H. J. Moore, S.L. Murchie, J.R. Murphy, T. J. Parker, R. Rieder, T.P. Rivellini, J. T. Schofield, A. Seiff, R.B. Singer, P. H. Smith, Laurence A. Soderblom, D.A. Spencer, C. R. Stoker, R. Sullivan, N. Thomas, S.W. Thurman, M.G. Tomasko, R. M. Vaughan, H. Wänke, A. W. Ward, G.R. Wilson
General geology and geomorphology of the Mars Pathfinder landing site General geology and geomorphology of the Mars Pathfinder landing site
The Mars Pathfinder (MPF) spacecraft landed on relatively young (late Hesperian-early Amazonian; 3.1-0.7 Ga) plains in Chryse Planitia near the mouth of Ares Vallis. Images returned from the spacecraft reveal a complex landscape of ridges and troughs, large hills and crater rims, rocks and boulders of various sizes and shapes, and surficial deposits, indicating a complex, multistage...
Authors
A. W. Ward, Lisa R. Gaddis, Randolph L. Kirk, Laurence A. Soderblom, K. L. Tanaka, M.P. Golombek, T. J. Parker, Ronald Greeley, R.O. Kuzmin
How useful is landslide hazard information? Lessons learned in the San Francisco Bay region How useful is landslide hazard information? Lessons learned in the San Francisco Bay region
Landslides, worldwide and in the United States, are arguably the most costly natural hazard. Substantial landslide information is available, but much of it remains underutilized, as a disconnect exists among geologists, decision makers, and the public. The lack of a national landslide insurance policy exacerbates this situation and promotes litigation as the principal recourse for...
Authors
D. G. Howell, D.W. Ramsey, E. E. Brabb
Digital photogrammetric analysis of the IMP camera images: Mapping the Mars Pathfinder landing site in three dimensions Digital photogrammetric analysis of the IMP camera images: Mapping the Mars Pathfinder landing site in three dimensions
This paper describes our photogrammetric analysis of the Imager for Mars Pathfinder data, part of a broader program of mapping the Mars Pathfinder landing site in support of geoscience investigations. This analysis, carried out primarily with a commercial digital photogrammetric system, supported by our in‐house Integrated Software for Imagers and Spectrometers (ISIS), consists of three...
Authors
Randolph L. Kirk, Elpitha Howington-Kraus, Trent M. Hare, E. Dorrer, D. Cook, Kris J. Becker, K. Thompson, B. Redding, J. Blue, D. Galuszka, E.M. Lee, Lisa R. Gaddis, J. R. Johnson, Laurence A. Soderblom, A. W. Ward, P. H. Smith, D.T. Britt
Aeolian features and processes at the Mars Pathfinder landing site Aeolian features and processes at the Mars Pathfinder landing site
The Mars Pathfinder landing site contains abundant features attributed to aeolian, or wind, processes. These include wind tails, drift deposits, duneforms of various types, ripplelike features, and ventifacts (the first clearly seen on Mars). Many of these features are consistant with formation involving sand-size particles. Although some features, such as dunes, could develop from...
Authors
Ronald Greeley, Michael Kraft, Robert Sullivan, Gregory Wilson, Nathan Bridges, Kenneth E. Herkenhoff, Ruslan O. Kuzmin, Michael Malin, Wes Ward
Ventifacts at the Pathfinder landing site Ventifacts at the Pathfinder landing site
About half of the rocks at the Mars Pathfinder Ares Vallis landing site appear to be ventifacts, rocks abraded by windborne particles. Comparable resolution images taken by the Imager for Mars Pathfinder (IMP) camera and the Viking landers show that ventifacts are more abundant at the Pathfinder site. The ventifacts occur in several forms, including rocks with faceted edges, finger‐like
Authors
N.T. Bridges, R. Greeley, A. F. C. Haldemann, Kenneth E. Herkenhoff, M. Kraft, T. J. Parker, A. W. Ward
Debris-flow origin for the Simud/Tiu deposit on Mars Debris-flow origin for the Simud/Tiu deposit on Mars
A late Hesperian smooth plains deposit on Mars interpreted as a debris flow extends more than 2000 km from Hydraotes Chaos, through Simud and Tiu Valles, and into Chryse Planitia. The Simud/Tiu deposit widens out to >1000 km and embays streamlined landforms and knobs made up of sedimentary and perhaps volcanic deposits that were carved by earlier channeling activity. Morphologic features...
Authors
K. L. Tanaka
Slopewash, surface runoff and fine-litter transport in forest and landslide scars in humid-tropical steeplands, Luquillo Experimental Forest, Puerto Rico Slopewash, surface runoff and fine-litter transport in forest and landslide scars in humid-tropical steeplands, Luquillo Experimental Forest, Puerto Rico
Rainfall, slopewash (the erosion of soil particles), surface runoff and fine-litter transport at humid-tropical steepland sites in the Luquillo Experimental Forest, Puerto Rico (18??20' N, 65??45' W) were measured from 1991 to 1995. Hillslopes underlain by (1) Cretaceous tuffaceous sandstone and siltstone in subtropical rain (tabonuco) forest with vegetation recovering from Hurricane...
Authors
M. C. Larsen, A. J. Torres-Sanchez, I.M. Concepcion
Steady-state flow of solid CO2: Preliminary results Steady-state flow of solid CO2: Preliminary results
To help answer the question of how much solid CO2 exists in the Martian south polar cap, we performed a series of laboratory triaxial deformation experiments at constant displacement rate in compression on jacketed cylinders of pure, polycrystalline CO2. Test conditions were temperatures 150 T 190 K, hydrostatic confining pressures 5≤ P ≤40 MPa, and strain rates 4.5×10−8 ≤ ε ≤4.3×10−4 s...
Authors
William B. Durham, Stephen H. Kirby, Laura A. Stern