Publications
Filter Total Items: 990
Massive CO2 ice deposits sequestered in the south polar layered deposits of Mars Massive CO2 ice deposits sequestered in the south polar layered deposits of Mars
Shallow Radar soundings from the Mars Reconnaissance Orbiter reveal a buried deposit of carbon dioxide (CO2) ice within the south polar layered deposits of Mars with a volume of 9500 to 12,500 cubic kilometers, about 30 times that previously estimated for the south pole residual cap. The deposit occurs within a stratigraphic unit that is uniquely marked by collapse features and other...
Authors
Roger J. Phillips, Brian J. Davis, Kenneth L. Tanaka, Shane Byrne, Michael T. Mellon, Nathaniel E. Putzig, Robert M. Haberle, Melinda A. Kahre, Bruce A. Campbell, Lynn M. Carter, Isaac B. Smith, John W. Holt, Suzanne E. Smrekar, Daniel C. Nunes, Jeffrey J. Plaut, Anthony F. Egan, Timothy N. Titus, Roberto Seu
Field Reconnaissance Geologic Mapping of the Columbia Hills, Mars: Results from MER Spirit and MRO HiRISE Observations Field Reconnaissance Geologic Mapping of the Columbia Hills, Mars: Results from MER Spirit and MRO HiRISE Observations
Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geologic history is well exposed...
Authors
L.S. Crumpler, R. E. Arvidson, S. W. Squyres, T. McCoy, A. Yingst, S. Ruff, W. Farrand, Y. McSween, M. Powell, D. W. Ming, R.V. Morris, J.F. Bell, J. Grant, R. Greeley, D. DesMarais, M. Schmidt, N.A. Cabrol, A. Haldemann, Kevin W. Lewis, A.E. Wang, C. Schroder, D. Blaney, B. Cohen, A. Yen, J. Farmer, Ralf Gellert, E.A. Guinness, K. E. Herkenhoff, J. R. Johnson, G. Klingelhofer, A. McEwen, J. W. Rice, M. Rice, P. deSouza, J. Hurowitz
Hypsometry of Titan Hypsometry of Titan
Cassini RADAR topography data are used to evaluate Titan’s hypsometric profile, and to make comparisons with other planetary bodies. Titan’s hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a...
Authors
Ralph D. Lorenz, Elizabeth P. Turtle, Bryan Stiles, Alice Le Gall, Alexander Hayes, Oded Aharonson, Charles A. Wood, Ellen Stofan, Randy Kirk
Mars atmospheric surface interactions and the CO2 cycle Mars atmospheric surface interactions and the CO2 cycle
Mars' northern and southern seasonal polar caps are formed during their respective autumn and winter seasons both by condensation of atmospheric carbon dioxide (CO2) directly onto the surface, and through atmospheric precipitation in the form of CO2 snow. During the polar spring and summer, the seasonal ice sublimes, returning CO2 to the atmosphere. Roughly 25% of the atmosphere, which...
Authors
Timothy N. Titus, Anthony Colaprete
Constraints on mechanisms for the growth of gully alcoves in Gasa crater, Mars, from two-dimensional stability assessments of rock slopes Constraints on mechanisms for the growth of gully alcoves in Gasa crater, Mars, from two-dimensional stability assessments of rock slopes
The value of slope stability analyses for gaining insight into the geologic conditions that would facilitate the growth of gully alcoves on Mars is demonstrated in Gasa crater. Two-dimensional limit equilibrium methods are used in conjunction with high-resolution topography derived from stereo High Resolution Imaging Science Experiment (HiRISE) imagery. These analyses reveal three...
Authors
Chris H. Okubo, Livio L. Tornabene, Nina L. Lanza
Regional-scale stratigraphy of surface units in Tyrrhena and Iapygia Terrae, Mars: Insights into highland crustal evolution and alteration history Regional-scale stratigraphy of surface units in Tyrrhena and Iapygia Terrae, Mars: Insights into highland crustal evolution and alteration history
The compositional, thermophysical and geologic characteristics of surface units in Iapygia and Tyrrhena Terra (60°E–100°E, 0°–30°S) provide new insights into the compositional stratigraphy of the region. Intercrater plains are dominated by two surface units. The older unit (unit 1) is deficient in olivine and more degraded and likely consists of a mixture of impact, volcanic and...
Authors
A. Deanne Rogers, Robin L. Fergason
Seasonal flows on warm Martian slopes Seasonal flows on warm Martian slopes
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm...
Authors
Alfred S. McEwen, Lujendra Ojha, Colin M. Dundas, Sarah S. Mattson, Shane Byrne, James J. Wray, Selby C. Cull, Scott L. Murchie, Nicolas Thomas, Virginia C. Gulick
Seasonal erosion and restoration of Mars' northern polar dunes Seasonal erosion and restoration of Mars' northern polar dunes
Despite radically different environmental conditions, terrestrial and martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here, we show that martian dunes are subject to an additional modification process not found on Earth: springtime sublimation of Mars' CO 2 seasonal...
Authors
C.J. Hansen, M. Bourke, Nathan T. Bridges, Shane Byrne, C. Colon, S. Diniega, Colin M. Dundas, Kenneth E. Herkenhoff, A. McEwen, M. Mellon, Ganna Portyankina, N. Thomas
The indication of Martian gully formation processes by slope-area analysis The indication of Martian gully formation processes by slope-area analysis
The formation process of recent gullies on Mars is currently under debate. This study aims to discriminate between the proposed formation processes - pure water flow, debris flow and dry mass wasting - through the application of geomorphological indices commonly used in terrestrial geomorphology. High-resolution digital elevation models (DEMs) of Earth and Mars were used to evaluate the...
Authors
Susan J. Conway, Matthew R. Balme, John B. Murray, Martin C. Towner, Chris Okubo, Peter M. Grindrod
Volcanism on Io: New insights from global geologic mapping Volcanism on Io: New insights from global geologic mapping
We produced the first complete, 1:15 M-scale global geologic map of Jupiter’s moon Io, based on a set of monochrome and color Galileo–Voyager image mosaics produced at a spatial resolution of 1 km/pixel. The surface of Io was mapped into 19 units based on albedo, color and surface morphology, and is subdivided as follows: plains (65.8% of surface), lava flow fields (28.5%), mountains (3...
Authors
David A. Williams, Laszlo P. Keszthelyi, David A. Crown, Jessica A. Yff, Windy L. Jaeger, Paul M. Schenk, Paul E. Geissler, Tammy L. Becker
Active aeolian processes on Mars: A regional study in Arabia and Meridiani Terrae Active aeolian processes on Mars: A regional study in Arabia and Meridiani Terrae
We present evidence of widespread aeolian activity in the Arabia Terra/Meridiani region (Mars), where different kinds of aeolian modifications have been detected and classified. Passing from the regional to the local scale, we describe one particular dune field in Meridiani Planum, where two ripple populations are distinguished by means of different migration rates. Moreover, a...
Authors
S. Silvestro, D.A. Vaz, L.K. Fenton, Paul E. Geissler
Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins
Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with Rb values determined for...
Authors
R. Cartwright, J.A. Clayton, Randolph L. Kirk