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Flow discharge and sediment transport models for estimating a minimum timescale of hydrological activity and channel and delta formation on Mars
Kleinhans, M. G.
This paper summarizes state-of-the-art models for water flow and sediment transport and suggests implications for the sediment grain size distribution, transport process, and delta formation. The flow velocity in Martian outflow channels is commonly calculated from the Manning equation, which is dimensionally incorrect and masks the large uncertai…
Origin and evolution of a cold-based tropical mountain glacier on Mars: The Pavonis Mons fan-shaped deposit
Head, James W.; Marchant, David R.; Shean, David E.
Each of the large Tharsis Montes volcanoes in the equatorial region of Mars has an unusual Amazonian-aged fan-shaped deposit on its west-northwestern flank. On the basis of Viking Orbiter data, the origin of these deposits has been variously ascribed to volcanic, mass-wasting, tectonic, and glacial processes. Using new MGS and Odyssey data, combin…
Fluid lava flows in Gusev crater, Mars
Greeley, Ronald; Williams, David A.; Neukum, Gerhard +6 more
Rocks on the floor of Gusev crater are basaltic in composition, as determined from measurements by the Mars Exploration Rover, Spirit. On the basis of compositional data, models of the basaltic lavas at the time of their emplacement suggest viscosities of 2.3 to 50 Pa . s (dependent on the number of phenocrysts and vesicles that were present), whi…
Groundwater-controlled valley networks and the decline of surface runoff on early Mars
Harrison, Keith P.; Grimm, Robert E.
Fluvial erosion on early Mars was dominated by valley networks created through a combination of groundwater processes and surface runoff. A reduced greenhouse effect due to CO2 loss, together with a declining geothermal heat flux, promoted the growth of a cryosphere and a Hesperian hydrologic regime dominated by outflow channel formatio…
Jupiter Thermospheric General Circulation Model (JTGCM): Global structure and dynamics driven by auroral and Joule heating
Waite, J. H.; Gladstone, G. R.; Bougher, S. W. +1 more
A growing multispectral database plus recent Galileo descent measurements are being used to construct a self-consistent picture of the Jupiter thermosphere/ionosphere system. The proper characterization of Jupiter's upper atmosphere, embedded ionosphere, and auroral features requires the examination of underlying processes, including the feedbacks…
Martian variable features: New insight from the Mars Express Orbiter and the Mars Exploration Rover Spirit
Greeley, Ronald; Whelley, Patrick L.; Neakrase, Lynn D. V. +12 more
Linear, low-albedo patterns (termed dark wind streaks) formed on the floor of Gusev crater between September 2003 and February 2004, as seen on High Resolution Stereo Camera images taken on board the Mars Express Orbiter. Pancam images from the Mars Exploration Rover Spirit show that the rover crossed a dark streak during its traverse to Bonnevill…
Styles and timing of volatile-driven activity in the eastern Hellas region of Mars
Crown, David A.; Bleamaster, Leslie F.; Mest, Scott C.
Recent analyses of Mars Global Surveyor and Mars Odyssey data sets provide new insights into the geologic evolution of the eastern Hellas region of Mars, in particular, the role of volatiles. Here, we present results of our recent work and integrate these with previous studies by various investigators to provide a synthesis of the history of volat…
Erosion by flowing Martian lava: New insights for Hecates Tholus from Mars Express and MER data
Greeley, Ronald; Williams, David A.; Neukum, Gerhard +2 more
We have used new compositional information on Martian basaltic rocks from the Mars Exploration Rover Spirit and data from new stereo imaging by the High Resolution Stereo Camera (HRSC) on the Mars Express orbiter to constrain an existing analytical-numerical computer model to assess the potential of Martian lavas to form lava channels by erosion o…
Major episodes of the hydrologic history in the region of Hesperia Planum, Mars
Neukum, G.; Marinangeli, L.; Ivanov, M. A. +5 more
The High Resolution Stereo Color camera (HRSC) data over Hesperia Planum and its surroundings reveal important details of geologic episodes and water-related processes in this region. (1) The Noachian fluvial events of Hesperia Planum depression included accumulation of water and formation of a water/ice reservoir there. Later, the reservoir was d…
Complex geology of two large impact craters in Tyrrhena Terra, Mars: Detailed analysis using MEX HRSC camera data
Neukum, G.; Korteniemi, J.; Kostama, V. -P. +5 more
Tyrrhena Terra, located just north of the roughly 200 km Hellas impact basin, is a typical region of the ancient cratered southern highlands on Mars. Its base material is a mixture of Hellas ejecta, prebasin remnants, and highland terrain, all later saturated with smaller (<200 km) impact craters. Fluvial and lacustrine deposits, erosion, tecto…