Publications
Filter Total Items: 915
Albedo of the south pole on Mars determined by topographic forcing of atmosphere dynamics
The nature of the martian south polar cap has remained enigmatic since the first spacecraft observations. In particular, the presence of a perennial carbon dioxide ice cap, the formation of a vast area of black ‘slab ice’ known as the Cryptic region and the asymmetric springtime retreat of the cap have eluded explanation. Here we present observations and climate modelling that indicate the south p
Authors
Anthony Colaprete, Jeffrey R. Barnes, Robert M. Haberle, Jeffery L. Hollingsworth, Hugh H. Kieffer, Timothy N. Titus
A microphysically-based approach to modeling emissivity and albedo of the martian seasonal caps
A new model of albedo and emissivity of the martian seasonal caps represented as porous CO2 slabs containing spherical voids and dust particles is described. In the model, a radiative transfer model is coupled with a microphysical model in order to link changes in albedo and emissivity to changes in porosity caused by ice metamorphism. The coupled model is capable of reproducing temporal changes i
Authors
Janusz Eluszkiewicz, Jean-Luc Moncet, Timothy N. Titus, Gary B. Hansen
Evidence from Opportunity’s Microscopic Imager for water on Meridiani Planum
The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing
Authors
Kenneth E. Herkenhoff, S. W. Squyres, R. Arvidson, D.S. Bass, J. F. III Bell, P. Bertelsen, B. L. Ehlmann, W. Farrand, Lisa R. Gaddis, R. Greeley, J. Grotzinger, A. G. Hayes, S.F. Hviid, J. R. Johnson, B. Jolliff, K.M. Kinch, A. H. Knoll, M.B. Madsen, J.N. Maki, S. M. McLennan, H.Y. McSween, D. W. Ming, J. W. Rice, L. Richter, M. Sims, P. H. Smith, Laurence A. Soderblom, Nicole Spanovich, R. Sullivan, S. Thompson, T. Wdowiak, C. Weitz, P. Whelley
Icelandic analogs to Martian flood lavas
We report on new field observations from Icelandic lava flows that have the same surface morphology as many Martian flood lava flows. The Martian flood lavas are characterized by a platy‐ridged surface morphology whose formation is not well understood. The examples on Mars include some of the most pristine lava on the planet and flows >1500 km long. The surfaces of the flows are characterized by (
Authors
Laszlo P. Keszthelyi, Thorvaldur Thordarson, Alfred McEwen, Henning Haack, Marie-Noelle Guilbaud, Stephen Self, Matti J. Rossi
RADAR: The Cassini Titan Radar Mapper
The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations in selecte
Authors
C. Elachi, M.D. Allison, L. Borgarelli, P. Encrenaz, E. Im, M.A. Janssen, W.T.K. Johnson, Randolph L. Kirk, R. D. Lorenz, J. I. Lunine, D.O. Muhleman, S.J. Ostro, G. Picardi, F. Posa, C.G. Rapley, L.E. Roth, R. Seu, Laurence A. Soderblom, S. Vetrella, S. D. Wall, C. A. Wood, H. A. Zebker
The face of the Moon: Lunar volcanoes and volcanic deposits
No abstract available.
Authors
Lisa R. Gaddis
Exploring Martian polar atmospheric circulation and surface interactions
The northern and southern seasonal polar caps of Mars are formed in the polar night, during their respective autumn and winter seasons, by the condensation of atmospheric CO2directly to the solid phase as ice, snow, and possibly frost. During spring and summer, the seasonal ice sublimes, returning CO2 to the atmosphere. The caps advance and recede in response to seasonal variations in solar insola
Authors
Thomas H. Prettyman, Timothy N. Titus
Textures of the soils and rocks at Gusev Crater from Spirit’s Microscopic Imager
The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous textures and evidence for alteration rinds, coatings, and veins consistent with secondary mineralizat
Authors
Kenneth E. Herkenhoff, S. W. Squyres, R. Arvidson, D.S. Bass, J. F. III Bell, P. Bertelsen, N.A. Cabrol, Lisa R. Gaddis, A. G. Hayes, S.F. Hviid, J. R. Johnson, K.M. Kinch, M.B. Madsen, J.N. Maki, S. M. McLennan, H.Y. McSween, J. W. Rice, M. Sims, P. H. Smith, Laurence A. Soderblom, Nicole Spanovich, R. Sullivan, A. Wang
Magnetic properties experiments on the Mars Exploration Rover Spirit at Gusev Crater
The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars—and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of ∼2% by weight. Th
Authors
P. Bertelsen, W. Goetz, M.B. Madsen, K.M. Kinch, S.F. Hviid, J. M. Knudsen, H.P. Gunnlaugsson, J. Merrison, P. Nørnberg, S. W. Squyres, J. F. III Bell, Kenneth E. Herkenhoff, S. Gorevan, A. S. Yen, T. Myrick, G. Klingelhoefer, R. Rieder, R. Gellert
Topographic mapping of Mars: From hectometer to micrometer scales
We describe USGS topomapping of Mars at resolutions from 100 m to 30 µm with data from the latest spacecraft missions. Analysis of NASA 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) data combining daytime visible reflected, daytime IR emitted, and nighttime IR emitted images allows us to isolate the physical effects of topography, albedo, and thermal inertia. To a good approximation t
Authors
Randolph L. Kirk, Steven W. Squyres, Gerhard Neukum
A new Mars Digital Image Model (MDIM 2.1) control network
The U.S. Geological Survey has recently completed a final revised version of its 231 m/pixel global Viking image mosaic of Mars that has substantially improved geodetic accuracy compared to versions released in 1991 and 2001. This mosaic, known as MDIM 2.1, is currently available in the USGS ISIS file format (see http://astrogeology.usgs.gov/Projects/MDIM21/) and will be formatted and submitted to
Authors
Brent A. Archinal, Ella M. Lee, Randolph L. Kirk, T. C. Duxbury, Robert M. Sucharski, Debbie Cook, Janet M. Barrett
A new Mars Digital Image Model (MDIM 2.1) control network
The U.S. Geological Survey has recently completed a final revised version of its 231 m/pixel global Viking image mosaic of Mars that has substantially improved geodetic accuracy compared to versions released in 1991 and 2001. This mosaic, known as MDIM 2.1, is currently available in the USGS ISIS file format and will be formatted and submitted to the NASA Planetary Data System (PDS) in the near fu
Authors
Brent A. Archinal, Ella M. Lee, Randolph L. Kirk, T. C. Duxbury, Robert M. Sucharski, Debbie Cook, Janet M. Barrett