Astrogeology Science Center

Publications

Filter Total Items: 833
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Year Published: 1990

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-...

Kirk, Randolph L.; Brown, Robert H.; Soderblom, Laurence A.

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Year Published: 1990

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...

Brown, R.H.; Kirk, Randolph L.; Johnson, T.V.; Soderblom, Laurence A.

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Year Published: 1990

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...

Soderblom, Laurence A.; Kieffer, S.W.; Becker, T.L.; Brown, R.H.; Cook, A.F.; Hansen, C.J.; Johnson, T.V.; Kirk, Randolph L.; Shoemaker, E.M.

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Year Published: 1990

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...

Gaddis, Lisa R.; Greeley, Ronald

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Year Published: 1990

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...

Geissler, Paul E.; Singer, Robert B.; Lucchitta, Baerbel K.

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Year Published: 1990

Flank tectonics of Martian volcanoes

On the flanks of Olympus Mons is a series of terraces, concentrically distributed around the caldera. Their morphology and location suggest that they could be thrust faults caused by compressional failure of the cone. In an attempt to understand the mechanism of faulting and the possible influences of the interior structure of Olympus Mons, we...

Thomas, Paul; Squyres, Steven W.; Carr, M.H.

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Year Published: 1990

Lava flow surface textures: SIR-B radar image texture, field observations, and terrain measurements

Space Shuttle Imaging Radar (SIR-8) images, field observations, and small-scale (cm) terrain measurements are used to study lava flow surface textures related to emplacement processes of a single hawaiian lava flow. Although smooth pahoehoe textures are poorly characterized on the SIR-B data, rougher pahoehoe types and the a'a flow portion show...

Gaddis, Lisa R.; Mouginis-Mark, Peter J.; Hayashi, Joan N.

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Year Published: 1990

Investigating climate change by digital analysis of blue-ice extent on satellite images of Antarctica

Landsat-5 Thematic Mapper (TM) and SPOT data collected two years apart from an identical area of Dronning (Queen) Maud Land, Antarctica, have been analyzed to detect variations in surface features that may signal climatic change, and to establish a technique that readily identifies such changes. We found that selective principal component analysis...

Orheim, Olav; Lucchitta, Baerbel K.

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Year Published: 1990

Young volcanic deposits in the Valles Marineris, Mars?

A study of the interior deposits of the central Valles Marineris has led to the discovery of a sequence of deposits that cover the chasma floors and range in thickness from that of thin dust to several kilometers. The emplacement of the deposits was the last major event in the history of the Valles Marineris, following deposition of older layered...

Lucchitta, Baerbel K.
Young volcanic deposits in the Valles Marineris, Mars?; 1990; Article; Journal; Icarus; Lucchitta, B. K.

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Year Published: 1989

Voyager 2 at Neptune: Imaging science results

Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds of methane ice suspended in an exceptionally clear atmosphere above a lower deck of hydrogen sulfide or ammonia ices. Neptune's atmosphere is dominated by a large anticyclonic storm system that has been named the Great Dark Spot (GDS). About the same size as Earth in...

Smith, B.A.; Soderblom, Laurence A.; Banfield, D.; Barnet, C.; Basilevsky, A.T.; Beebe, R.F.; Bollinger, K.; Boyce, J.M.; Brahic, A.; Briggs, G.A.; Brown, R.H.; Chyba, C.; Collins, S.A.; Colvin, T.; Cook, A.F.; Crisp, D.; Croft, S.K.; Cruikshank, D.; Cuzzi, J.N.; Danielson, G.E.; Davies, M.E.; DeJong, E.; Dones, L.; Godfrey, D.; Goguen, J.; Grenier, I.; Haemmerle, V.; Hammel, H. ; Hansen, C.J.; Helfenstein, C.P.; Howell, C.; Hunt, G.E.; Ingersoll, A.P.; Johnson, T.V.; Kargel, J.; Kirk, Randolph L.; Kuehn, D.I.; Limaye, S.; Masursky, H.; McEwen, A.; Morrison, D.; Owen, T.; Owen, W.; Pollack, J.B.; Porco, C.C.; Rages, K.; Rogers, P.; Rudy, D.; Sagan, C.; Schwartz, J.; Shoemaker, E.M.; Showalter, M.; Sicardy, B.; Simonelli, D.; Spencer, J.; Sromovsky, L.A.; Stoker, C.; Strom, R.G.; Suomi, V.E.; Synott, S.P.; Terrile, R.J.; Thomas, P.; Thompson, W.R.; Verbiscer, A.; Veverka, J.

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Year Published: 1989

The case for planetary sample return missions

The essential role of planetary sample studies in exploration of the solar system has been well established “Drake et al., 1987”. As part of the larger pursuit of comparative planetology, samples of other rocky planets (Mercury, Venus, Mars), planetary satellites, asteroids, and comets should reveal much about the materials and processes that...

Gooding, James L.; Carr, M.H.; McKay, Christopher P

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Year Published: 1989

Geologic analyses of Shuttle Imaging Radar (SIR-B) data of Kilauea Volcano, Hawaii

Analyses of imaging radar data of volcanic terranes on Earth and Venus have emphasized the need for a clearer understanding of how these data can be most effectively used to accomplish important volcanological goals, including the interpretation of eruptive styles and the characterization of the geologic history of volcanic centers. The second...

Gaddis, Lisa R.; Mouginis-Mark, Peter J.; Singer, Robert B.; Kaupp, Verne