Search Publications
Elevation distribution of Titan's craters suggests extensive wetlands
Lorenz, R. D.; Neish, C. D.
Using a new global topographic map of Titan, we find that craters on Titan preferentially lie at higher than average elevations. We explore several explanations for this observed behavior, and judge the most reasonable explanation to be the presence of widespread wetlands of liquid hydrocarbons at low elevations over much of geologic time. Impacts…
Valles Marineris dune fields as compared with other martian populations: Diversity of dune compositions, morphologies, and thermophysical properties
Chojnacki, Matthew; Moersch, Jeffrey E.; Burr, Devon M.
Planetary dune field properties and their bulk bedform morphologies relate to regional wind patterns, sediment supply, climate, and topography. On Mars, major occurrences of spatially contiguous low-albedo sand dunes are primarily found in three major topographic settings: impact craters, high-latitude basins, and linear troughs or valleys, the la…
Temperature dependence of the sublimation rate of water ice: Influence of impurities
Kossacki, Konrad J.; Leliwa-Kopystynski, Jacek
The sublimation rate of ice is commonly calculated using the simple Hertz-Knudsen formula. This formula is derived from the kinetic theory of gases and ignores microphysical processes determining the actual sublimation rate. The microphysical processes can be accounted for by including the temperature dependent sublimation coefficient (Kossacki, K…
Volcano-ice interactions in the Arsia Mons tropical mountain glacier deposits
Head, James W.; Marchant, David R.; Wilson, Lionel +1 more
Fan-shaped deposits (FSD) superposed on the sides of the Tharsis Montes volcanic edifices are widely interpreted to have been formed by cold-based glaciation during the Late Amazonian, a period when the Tharsis Montes were volcanically active. We survey the ∼166,000 km2 Arsia Mons FSD using new, high-resolution image and topography data…
Physics of saltation and sand transport on Titan: A brief review
Lorenz, Ralph D.
Key physical aspects of saltation and sand transport on Titan are reviewed, and the sensitivity of saltation parameters to assumptions about sand composition (most likely of 'heavy' organics) is explored. The possibility of significant triboelectric charging of sediments in Titan's low-conductivity environment is noted, and given Titan's low gravi…
Structure and dynamics of Titan’s outer icy shell constrained from Cassini data
Čadek, Ondřej; Tobie, Gabriel; Choblet, Gaël +1 more
The Cassini-Huygens mission has brought evidence for an internal ocean lying beneath an outer icy shell on Titan. The observed topography differs significantly from the reference hydrostatic shape, while the measured geoid anomalies (estimated up to degree three) remain weak. This suggests compensation either by deflections of the ocean/ice interf…
Phobos mass determination from the very close flyby of Mars Express in 2010
Pätzold, M.; Asmar, S. W.; Häusler, B. +3 more
The global geophysical parameters GMPh=(0.7072±0.0013)×10-3 km3 s-2, C20, C22 and the bulk density <ρ>=(1862±30) kg/m3 have been determined from the closest Mars Express flyby at the Mars moon Phobos on 3rd March 2010 at a distance of 77 km. The second degree gravit…
Valley formation by groundwater seepage, pressurized groundwater outbursts and crater-lake overflow in flume experiments with implications for Mars
Marra, Wouter A.; Braat, Lisanne; Baar, Anne W. +1 more
Remains of fluvial valleys on Mars reveal the former presence of water on the surface. However, the source of water and the hydrological setting is not always clear, especially in types of valleys that are rare on Earth and where we have limited knowledge of the processes involved. We investigated three hydrological scenarios for valley formation …
Open flux in Saturn’s magnetosphere
Gérard, Jean-Claude; Clarke, John T.; Badman, Sarah V. +2 more
We characterise the interaction between the solar wind and Saturn's magnetosphere by evaluating the amount of 'open' magnetic flux connected to the solar wind. This is deduced from a large set of Hubble Space Telescope images of the ultraviolet aurora, using the poleward boundary of the main aurora as a proxy for the open-closed field line boundar…
Reconstructing the aqueous history within the southwestern Melas basin, Mars: Clues from stratigraphic and morphometric analyses of fans
Williams, Rebecca M. E.; Weitz, Catherine M.
New details of the aqueous history in the southwestern Melas Chasma elevated basin have been revealed from analysis of high-resolution image, topographic and spectral datasets. We have identified eleven fan-shaped landforms that reflect various depositional environments. A distinctive marker bed with inferred indurated aeolian bedforms is within t…