Publications
Filter Total Items: 915
Velocity measurements and changes in position of Thwaites Glacier/iceberg tongue from aerial photography, Landsat images and NOAA AVHRR data
The Thwaites Glacier/iceberg tongue complex has been a significant feature of the Antarctic coastline for at least 50 years. In 1986, major changes began to occur in this area. Fast ice melted and several icebergs calved from the base of the iceberg tongue and the terminus of Thwaites Glacier. The iceberg tongue rotated to an east-west orientation and drifted westward. Between 1986 and 1992, a tot
Authors
Jane G. Ferrigno, Baerbel K. Lucchitta, A. L. Mullinsallison, Robert J. Allen, W. G. Gould
Antarctic glacier-tongue velocities from Landsat images: First results
We measured the velocities of six glacier tongues and a few tongues within ice shelves distributed around the Antarctic coastline by determining the displacement of crevasse patterns seen on sequential Landsat images. The velocities range from less than 0.2 km a−1 for East Antarctic ice-shelf tongues to more than 2.5 km a−1 for the Thwaites Glacier Tongue. All glacier tongues show increases in vel
Authors
Baerbel K. Lucchitta, K.F. Mullins, A.L. Allison, Jane G. Ferrigno
Enhanced visualization for the interpretation of Magellan radar data: Supplement to the Magellan special issue
The differences of radar data from more familiar photographic images, coupled with the unique geologic characteristics of Venus's surface, can make interpretation of the standard Magellan data products difficult for both planetary scientists and nonspecialists. We describe a set of digital processing techniques for transforming individual remote‐sensing datasets in order to make the information th
Authors
Randolph L. Kirk, Laurence A. Soderblom, Ella M. Lee
The geology and distribution of impact craters on Venus: What are they telling us?
Magellan has revealed an ensemble of impact craters on Venus that is unique in many important ways. We have compiled a data base describing the 842 craters on 89% of Venus' surface mapped through orbit 2578. (The craters range in diameter from 1.5 to 280 km.) We have studied the distribution, size‐density, morphology, geology, and associated surface properties of these craters both in the aggregat
Authors
G. G. Schaber, R.G. Strom, H. J. Moore, Laurence A. Soderblom, Randolph L. Kirk, D.J. Chadwick, D.D. Dawson, Lisa R. Gaddis, J. M. Boyce, Joel F. Russell
Lunar impact basins and crustal heterogeneity: New western limb and far side data from Galileo
Multispectral images of the lunar western limb and far side obtained from Galileo reveal the compositional nature of several prominent lunar features and provide new information on lunar evolution. The data reveal that the ejecta from the Orientale impact basin (900 kilometers in diameter) lying outside the Cordillera Mountains was excavated from the crust, not the mantle, and covers pre-Orientale
Authors
Michael J.S. Belton, James W. Head, Carle m. Pieters, Ronald Greeley, Alfred S. McEwen, G. Neukum, Kenneth P. Klaasen, C.D. Anger, M. H. Carr, C. R. Chapman, M. E. Davies, F. P. Fanale, P.J. Gierasch, R. Greenberg, A. Ingersoll, Torrence Johnson, B. Paczkowski, C.B. Pilcher, J. Veverka
The canyon system on Mars
Individual Martian equatorial troughs are described, and their stratigraphy, geomorphology and structure are discussed. Possible origins and the overall sequence of events are addressed. Wall rock, interior layered deposits, irregular floor deposits, fractured floor material, and surficial deposits are examined. Chasma walls, wall stability, pits and pit chains, tributary canyons, and the transiti
Authors
Baerbel K. Lucchitta, A. S. McEwen, Gary D. Clow, Paul E. Geissler, R.B. Singer, R. A. Schultz, Steven W. Squyres
Lava-flow characterization at Pisgah Volcanic Field, California, with multiparameter imaging radar
Multi-incidence-angle (in the 25° to 55° range) radar data acquired by the NASA/JPL Airborne Synthetic Aperture Radar (AIRSAR) at three wavelengths simultaneously and displayed at three polarizations are examined for their utility in characterizing lava flows at Pisgah volcanic field, California. Pisgah lava flows were erupted in three phases; flow textures consist of hummocky pahoehoe, smooth pah
Authors
Lisa R. Gaddis
Subsurface energy storage and transport for solar-powered geysers on Triton
The location of active geyser-like eruptions and related features close to the current subsolar latitude on Triton suggests a solar energy source for these phenomena. Solidstate greenhouse calculations have shown that sunlight can generate substantially elevated subsurface temperatures. A variety of models for the storage of solar energy in a sub-greenhouse layer and for the supply of gas and ener
Authors
Randolph L. Kirk, Robert H. Brown, Laurence A. Soderblom
Energy sources for triton's geyser-like plumes
Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequent
Authors
R. H. Brown, Randolph L. Kirk, T. V. Johnson, Laurence A. Soderblom
Triton's geyser-like plumes: Discovery and basic characterization
At least four active geyser-like eruptions were discovered in Voyager 2 images of Triton, Neptune's large satellite. The two best documented eruptions occur as columns of dark material rising to an altitude of about 8 kilometers where dark clouds of material are left suspended to drift downwind over 100 kilometers. The radii of the rising columns appear to be in the range of several tens of meters
Authors
Laurence A. Soderblom, S. W. Kieffer, T.L. Becker, R. H. Brown, A.F. Cook, C.J. Hansen, T. V. Johnson, Randolph L. Kirk, E.M. Shoemaker
Volcanism in Northwest Ishtar Terra, Venus
Soviet Venera 15/16 radar images and topographic data for an area in NW Ishtar Terra, Venus (74°N, 313°E) contain evidence for the existence of a complex volcanic center. Located at the intersection of Akna and Freyja Montes (both elevated ∼4 to 7 km above the planetary reference radius of 6051 km), this volcanic center has a complex caldera system, possibly more than one major eruptive vent, and
Authors
Lisa R. Gaddis, Ronald Greeley
Dark materials in Valles Marineris: Indications of the style of volcanism and magmatism on Mars
Rifting on the equatorial canyon system of Valles Marineris provides a unique view of the interior of the Martian crust to depths reaching 7 km, exposing several in situ bedrock units which testify to past volcanic and magmatic processes on Mars. A thick, regionally extensive deposit observed in Coprates and Juventae chasmata is interpreted on the basis of spectral reflectance, erosional morpholog
Authors
Paul E. Geissler, Robert B. Singer, Baerbel K. Lucchitta