Publications
Filter Total Items: 978
Geology and Surface Processes on Titan Geology and Surface Processes on Titan
The surface of Titan has been revealed globally, if incompletely, by Cassini observations at infrared and radar wavelengths as well as locally by the instruments on the Huygens probe. Extended dune fields, lakes, mountainous terrain, dendritic erosion patterns and erosional remnants indicate dynamic surface processes. Valleys, small-scale gullies and rounded cobbles such as those...
Authors
Ralf Jaumann, Randolph L. Kirk, Ralph D. Lorenz, Rosaly Lopes, Ellen Stofan, Elizabeth P. Turtle, Horst Uwe Keller, Charles A. Wood, Christophe Sotin, Laurence A. Soderblom, Martin G. Tomasko
Observations of the north polar water ice annulus on Mars using THEMIS and TES Observations of the north polar water ice annulus on Mars using THEMIS and TES
The Martian seasonal CO2 ice caps advance and retreat each year. In the spring, as the CO2 cap gradually retreats, it leaves behind an extensive defrosting zone from the solid CO2 cap to the location where all CO2 frost has sublimated. We have been studying this phenomenon in the north polar region using data from the THermal EMission Imaging System (THEMIS), a visible and infra-red (IR)...
Authors
Kiri L. Wagstaff, Timothy N. Titus, Anton B. Ivanov, Rebecca Castano, Joshua L. Bandfield
Dunes on Titan observed by Cassini Radar Dunes on Titan observed by Cassini Radar
Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ±30° of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other...
Authors
J. Radebaugh, R. D. Lorenz, J. I. Lunine, S. D. Wall, G. Boubin, E. Reffet, Randolph L. Kirk, R.M. Lopes, E. R. Stofan, Laurence A. Soderblom, M. Allison, M. Janssen, P. Paillou, P. Callahan, Carl Spencer
Hematite spherules at Meridiani: results from MI, Mini-TES, and Pancam Hematite spherules at Meridiani: results from MI, Mini-TES, and Pancam
We report on observations of hematite‐bearing spherules at Meridiani Planum made using the Microscopic Imager (MI), Mini‐Thermal Emission Spectrometer (Mini‐TES), and Panoramic Camera (Pancam) instruments on the Mars Exploration Rover Opportunity. Spherules were observed on soil surfaces and in outcrop rocks, both on undisturbed surfaces and in abraded surfaces ground using the Rock...
Authors
W. M. Calvin, J.D. Shoffner, J. R. Johnson, A.H. Knoll, J.M. Pocock, S. W. Squyres, C.M. Weitz, R. E. Arvidson, J.F. Bell, P. R. Christensen, P. A. de Souza, W. H. Farrand, T.D. Glotch, Kenneth E. Herkenhoff, B.L. Jolliff, A.T. Knudson, S. M. McLennan, A.D. Rogers, S.D. Thompson
Titan's diverse landscapes as evidenced by Cassini RADAR's third and fourth looks at Titan Titan's diverse landscapes as evidenced by Cassini RADAR's third and fourth looks at Titan
Cassini's third and fourth radar flybys, T7 and T8, covered diverse terrains in the high southern and equatorial latitudes, respectively. The T7 synthetic aperture radar (SAR) swath is somewhat more straightforward to understand in terms of a progressive poleward descent from a high, dissected, and partly hilly terrain down to a low flat plain with embayments and deposits suggestive of...
Authors
J. I. Lunine, C. Elachi, S. D. Wall, M.A. Janssen, M.D. Allison, Y. Anderson, R. Boehmer, P. Callahan, P. Encrenaz, E. Flamini, G. Franceschetti, Y. Gim, G. Hamilton, S. Hensley, W.T.K. Johnson, K. Kelleher, Randolph L. Kirk, R.M. Lopes, R. Lorenz, D.O. Muhleman, R. Orosei, S.J. Ostro, F. Paganelli, P. Paillou, G. Picardi, F. Posa, J. Radebaugh, L.E. Roth, R. Seu, S. Shaffer, Laurence A. Soderblom, B. Stiles, E. R. Stofan, S. Vetrella, R. West, C. A. Wood, L. Wye, H. Zebker, G. Alberti, E. Karkoschka, B. Rizk, E. McFarlane, C. See, B. Kazeminejad
Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES)
Previous observations have noted the change in albedo in a number of North Pole bright outliers and in the distribution of bright ice deposits between Mariner 9, Viking, and Mars Global Surveyor (MGS) data sets. Changes over the summer season as well as between regions at the same season (Ls) in different years have been observed. We used the bolometric albedo and brightness temperature...
Authors
Wendy M. Calvin, Timothy N. Titus
Titan's inventory of organic surface materials Titan's inventory of organic surface materials
Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20%...
Authors
Ralph D. Lorenz, Karl L. Mitchell, Randolph L. Kirk, Alexander G. Hayes, Oded Aharonson, Howard A. Zebker, Philipe Paillou, Jani Radebaugh, Jonathan I. Lunine, Michael A. Janssen, Stephen D. Wall, Rosaly Lopes, Bryan Stiles, Steven J. Ostro, Giuseppe Mitri, Ellen R. Stofan
HiRISE observations of fractured mounds: Possible Martian pingos HiRISE observations of fractured mounds: Possible Martian pingos
Early images from the High Resolution Imaging Science Experiment (HiRISE) camera have revealed small fractured mounds in the Martian mid‐latitudes. HiRISE resolves fractures on the mound surfaces, indicating uplift, and shows that the mound surface material resembles that of the surrounding landscape. Analysis of Mars Orbiter Camera (MOC) images shows that in Utopia Planitia the mounds...
Authors
Colin M. Dundas, Michael T. Mellon, Alfred S. McEwen, Alexandra Lefort, Laszlo P. Keszthelyi, Nicolas Thomas
Quasi-periodic bedding in the sedimentary rock record of mars Quasi-periodic bedding in the sedimentary rock record of mars
Widespread sedimentary rocks on Mars preserve evidence of surface conditions different from the modern cold and dry environment, although it is unknown how long conditions favorable to deposition persisted. We used 1-meter stereo topographic maps to demonstrate the presence of rhythmic bedding at several outcrops in the Arabia Terra region. Repeating beds are ∼10 meters thick, and one...
Authors
Kevin W. Lewis, Oded Aharonson, John P. Grotzinger, Randolph L. Kirk, Alfred S. McEwen, Terry-Ann Suer
High Resolution Imaging Science Experiment (HiRISE) observations of glacial and periglacial morphologies in the circum-Argyre Planitia highlands, Mars High Resolution Imaging Science Experiment (HiRISE) observations of glacial and periglacial morphologies in the circum-Argyre Planitia highlands, Mars
The landscape of the Argyre Planitia and adjoining Charitum and Nereidum Montes in the southern hemisphere of Mars has been heavily modified since formation of the Argyre impact basin. This study examines morphologies in the Argyre region revealed in images acquired by the High Resolution Imaging Science Experiment (HiRISE) camera and discusses the implications for glacial and...
Authors
Maria E. Banks, Alfred S. McEwen, Jeffrey S. Kargel, Victor R. Baker, Robert G. Strom, Michael T. Mellon, Virginia C. Gulick, Laszlo P. Keszthelyi, Kenneth E. Herkenhoff, Jon D. Pelletier, Windy L. Jaeger
Columbia Hills, Mars: aeolian features seen from the ground and orbit Columbia Hills, Mars: aeolian features seen from the ground and orbit
Abundant wind-related features occur along Spirit's traverse into the Columbia Hills over the basaltic plains of Gusev Crater. Most of the windblown sands are probably derived from weathering of rocks within the crater, and possibly from deposits associated with Ma'adim Vallis. Windblown particles act as agents of abrasion, forming ventifacts, and are organized in places into various bed...
Authors
Ronald Greeley, Patrick L. Whelley, Lynn Neakrase, Raymond E. Arvidson, Nathan T. Bridges, Nathalie A. Cabrol, Phillip R. Christensen, Kaichang Di, Daniel J. Foley, Matthew P. Golombek, Kenneth E. Herkenhoff, Amy Knudson, Ruslan O. Kuzmin, Ron Li, Timothy Michaels, Steven W. Squyres, Robert Sullivan, Shane D. Thompson
Cartography for lunar exploration: 2008 status and mission plans Cartography for lunar exploration: 2008 status and mission plans
The initial spacecraft exploration of the Moon in the 1960s-70s yielded extensive data, primarily in the form of film and television images, which were used to produce a large number of hardcopy maps by conventional techniques. A second era of exploration, beginning in the early 1990s, has produced digital data including global multispectral imagery and altimetry, from which a new...
Authors
Randolph L. Kirk, Brent A. Archinal, Lisa R. Gaddis, Mark R. Rosiek