Astrogeology Science Center

Publications

Filter Total Items: 845
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Year Published: 1995

Data base of impact craters on Venus based on analysis of Magellan radar images and altimetry data

No abstract available.

Schaber, Gerald G.; Kirk, Randolph L.; Strom, Robert G.

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Year Published: 1995

Reply to comment on the global resurfacing of Venus

No abstract available.

Strom, R.G.; Schaber, G.G.; Dawson, D.D.; Kirk, Randolph L.

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Year Published: 1995

Velocities and mass balance of Pine Island Glacier, West Antarctica, derived from ERS-1 SAR images

Pine Island Glacier is one of the major ice streams draining West Antarctica. We calculated average velocities for both its grounded and floating parts by tracking crevasses and other patterns moving with the ice on two sequential images acquired in February and December 1992 by ERS-1 SAR (European Remote-Sensing Satellite, Synthetic Aperture...

Lucchitta, Baerbel K.; Rosanova, Christina E.; Mullins, K.F.

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Year Published: 1995

Geology of Triton

Triton, with a diameter of ≡2700 km, is Neptune's only planet-class satellite. The complexity of Triton's surface and the variety of surface features is unequaled among the satellites of the solar system. From a geologic viewpoint, some of Triton's features have apparently familiar morphologies and general interpretative agreement exists. However...

Cruikshank, Dale P.; Croft, S.K.; Kargel, J.S.; Kirk, Randolph L.; Moore, J.M.; Schenk, P.M.; Strom, R.G.

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Year Published: 1995

Triton's plumes: Discovery, characteristics, and models

This chapter presents (1) basic observations and characteristics of Triton's plumes (scale, geometry, optical properties, and temporal behavior); (2) the current best estimates of other parameters that can be derived directly or inferred from the observations (plume duration, wind velocities, particle properties, mass fluxes, energy requirements,...

Cruikshank, Dale P.; Kirk, Randolph L.; Soderblom, Laurence A.; Brown, R. H.; Kieffer, S.W.; Kargel, J.S.

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Year Published: 1994

Venus cartography

The entire surface of the planet Venus is being mapped at global and regional scales (1:50,000,000 through 1:1,500,000) with synthetic aperture radar (SAR), radar altimeter, and radiometer measurements of physical properties from the Magellan spacecraft. The mapping includes SAR image mosaics, shaded relief maps, and topographic contour overlays...

Batson, R.M.; Kirk, Randolph L.; Edwards, Kathleen; Morgan, H.F.

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Year Published: 1994

Evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at Pisgah Volcanic Field, California

Comparison of radar backscatter coefficients (σ°, in dB), calculated by using the empirical model of Oh et al. [1992], to σ° extracted from AIRSAR data of four geologic units at Pisgah shows that the model predicts measured σ°vv and σ°hv to within ±3 dB. The model predicts higher σ°hh than those observed. For smooth surfaces (rms...

Gaddis, Lisa R.

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Year Published: 1994

Topography of Valles Marineris: Implications for erosional and structural history

Compilation of a simplified geologic/geomorphic map onto digital terrain models of the Valles Marineris permitted an evaluation of elevations in the vicinity of the troughs and the calculation of depth of troughs below surrounding plateaus, thickness of deposits inside the troughs, volumes of void spaces above geologic/geomorphic units, and...

Lucchitta, Baerbel K.; Isbell, N.K.; Howington-Kraus, Elpitha

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Year Published: 1994

Coupling of volatile transport and internal heat flow on Triton

Recently Brown et al. (1991) showed that Triton's internal heat source could amount to 5–20% of the absorbed insolation on Triton, thus significantly affecting volatile transport and atmospheric pressure. Subsequently, Kirk and Brown (1991a) used simple analytical models of the effect of internal heat on the distribution of volatiles on Triton's...

Brown, Robert H.; Kirk, Randolph L.

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Year Published: 1994

Velocities of the Smith Glacier Ice Tongue and Dotson Ice Shelf, Walgreen Coast, Marie Byrd Land, West Antarctica

Velocity measurements were made for two time intervals on the Smith Glacier ice tongue (1973–88 and 1988–90) and three on the Dotson Ice Shelf (1972–88, 1973–88 and 1988–90). The Smith Glacier ice tongue velocities for the two intervals are similar near the grounding line but show a progressive increase toward the terminus in the late 1980s. The...

Lucchitta, Baerbel K.; Mullins, Kevin F.; Smith, C. E.; Ferrigno, Jane G.

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Year Published: 1994

Carbonate-Sulfate Volcanism on Venus?

Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resemble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely...

Kargel, Jeffrey S.; Kirk, Randolph L.; Fegley, Bruce; Treiman, Allan H.

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Year Published: 1994

Galileo Photometry of Asteroid 951 Gaspra

Galileo images of Gaspra make it possible for the first time to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over a wide range of incidence and emission angles and by extending the phase angle coverage to phases not observable from Earth. We combine Earth-based telescopic photometry over...

Helfenstein, P.; Veverka, J.; Thomas, P.C.; Simonelli, D.P.; Lee, P.; Klaasen, K.; Johnson, T. V.; Breneman, H.; Head, J.W.; Murchie, S.; Fanale, F.; Robinson, M.; Clark, B.; Granahan, J.; Garbeil, H.; McEwen, A.S.; Kirk, Randolph L.; Davies, M.; Neukum, G.; Mottola, S.; Wagner, R.; Belton, M.; Chapman, C.; Pilcher, C.