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Alberto G. FAIRÉN,
James M. DOHM, Victor R. BAKER,
Shane D. THOMPSON,
William C. MAHANEY,
Kenneth E. HERKENHOFF,
J. Alexis P. RODRÍGUEZ,
Alfonso F. DAVILA,
Dirk SCHULZE-MAKUCH,
M. Ramy EL MAARRY,
Esther R. UCEDA,
Ricardo AMILS,
Hirdy MIYAMOTO,
Kyeong J. KIM,
Robert C. ANDERSON,
Christopher P. McKAY
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ABSTRACT: Abstract– Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25 km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10–80 m of deflation in the last 3–3.5 Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface.
Meteoritics & Planetary Science. 11/2011; 46(12):1832 - 1841.
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ABSTRACT: The Mars Orbital Camera onboard the Mars Global Surveyor spacecraft, which is currently orbiting about Mars, has revealed hundreds of pristine lobate and tongue-shaped flows that closely display the morphological characteristics of terrestrial rock glaciers, both tongue- and lobe-shaped forms. Generally located between 30°S and 47°S latitude on Mars, these terrestrial-like flows have important paleoenvironmental implications, including marking environmental change from current, present cold and dry desert martian conditions to cold wetter climates in the past. Paleoenvironmental conditions, hypothesized to have significantly influenced the dimensions of the terrestrial-like flows, is supported through a simple dynamic model with the power-law rheology. The presence of periglacial landforms on Mars indicates the possible presence of permafrost and potential caches of water for future exobiological exploration.
Planetary and Space Science 01/2007; 55:181-192. · 2.22 Impact Factor
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Environmental Modelling and Software. 01/2007; 22:1400-1408.
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ABSTRACT: We explore applications of thermodynamics to hydrology, in particular the application of extremization principles to self-organized
river networks. Two thermodynamic principles have been applied to river networks: (1) the most probable state of a system
is that its configurational entropy is a maximum, corresponding to dissipation spread evenly throughout the network, and (2)
the principle of minimum total energy dissipation, similar to the principle of minimum entropy production. We also discuss
the power-law characteristics that are observed in river networks and show how they arise in model networks. We also note
the application of these principles to shoreline profiles.
01/2006: pages 135-146;
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ABSTRACT: Venus and Mars likely had liquid water bodies on their surface early in the Solar System history. The surfaces of Venus and Mars are presently not a suitable habitat for life, but reservoirs of liquid water remain in the atmosphere of Venus and the subsurface of Mars, and with it also the possibility of microbial life. Microbial organisms may have adapted to live in these ecological niches by the evolutionary force of directional selection. Missions to our neighboring planets should therefore be planned to explore these potentially life-containing refuges and return samples for analysis. Sample return missions should also include ice samples from Mercury and the Moon, which may contain information about the biogenic material that catalyzed the early evolution of life on Earth (or elsewhere). To obtain such information, science-driven exploration is necessary through varying degrees of mission operation autonomy. A hierarchical mission design is envisioned that includes spaceborne (orbital), atmosphere (airborne), surface (mobile such as rover and stationary such as lander or sensor), and subsurface (e.g., ground-penetrating radar, drilling, etc.) agents working in concert to allow for sufficient mission safety and redundancy, to perform extensive and challenging reconnaissance, and to lead to a thorough search for evidence of life and habitability.
Astrobiology 01/2006; 5(6):778-95. · 2.15 Impact Factor
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ABSTRACT: Subsurface water processes are common for planetary bodies in the solar system and are highly probable for exoplanets (planets outside the solar system). For many solar system objects, the subsurface water exists as ice. For Earth and Mars, subsurface saturated zones have occurred throughout their planetary histories. Earth is mostly clement with the recharge of most groundwater reservoirs from ample precipitation during transient ice- and hot-house conditions, as recorded through the geologic and fossilized records. On the other hand, Mars is mostly in an ice-house stage, which is interrupted by endogenic-driven activity. This activity catastrophically drives short-lived hydrological cycling and associated climatic perturbations. Regional aquifers in the Martian highlands that developed during past, more Earth-like conditions delivered water to the northern plains. Water was also cycled to the South Polar Region during changes in climate induced by endogenic activity and/or by changes in Mars orbital parameters. Venus very likely had a warm hydrosphere for hundreds of millions of years, before the development of its current extremely hot atmosphere and surface. Subsequently, Venus lost its hydrosphere as solar luminosity increased and a run-away moist greenhouse took effect. Subsurface oceans of water or ammonia-water composition, induced by tidal forces and radiogenic heating, probably occur on the larger satellites Europa, Ganymede, Callisto, Titan, and Triton. Tidal forces operating between some of the small bodies of the outer solar system could also promote the fusion of ice and the stability of inner liquid-water oceans.Los procesos hdricos subsuperficiales son comunes en cuerpos planetarios del sistema solar y son altamente probables para exoplanetas (planetas fuera del sistema solar). Para muchos cuerpos del sistema solar, el agua subsuperficial existe como hielo. Para la Tierra y Marte han ocurrido zonas saturadas subsuperficiales a travs de sus historias planetarias. La Tierra es principalmente generosa con la recarga de la mayora de reservorios de aguas subterrneas a partir de amplia precipitacin reconocida en condiciones transitorias calientes y heladas, tal y como aparece en los registros fsiles y geolgicos. Por otro lado, Marte se encuentra principalmente en una etapa de cmara de hielo la cual es interrumpida por actividad de tipo endognico. Esta actividad pone en funcionamiento catastrficamente ciclos hidrolgicos de vida corta y perturbaciones climticas asociadas. Acuferos regionales en las montaas de Marte que se desarrollaron en el pasado en condiciones similares a la Tierra distribuyen agua a las planicies del norte. El agua ha sido transportada hacia el sur de la regin polar durante cambios en el clima inducidos por actividad endognica y/o cambios en los parmetros orbitales de Marte. Venus muy probablemente tuvo una hidrsfera caliente durante cientos de millones de aos, antes de que se desarrollara su atmsfera y superficie actual extremadamente caliente. Subsecuentemente, Venus perdi su hidrsfera a medida que la luminosidad solar aument y un efecto de invernadero hmedo escapatorio se llev a cabo. Ocanos subsuperficiales de composicin agua o amoniaco-agua, inducidos por fuerzas de marea y calentamiento radiognico, probablemente ocurren en los satlites ms grandes como Europa, Ganimeda, Callisto, Titan y Triton. Las fuerzas de marea que operan entre los cuerpos pequeos del sistema solar externo podran tambin promover la fusin de hielo y la estabilidad de lquido interno-aguas de los ocanos. Les processus de subsurface impliquant leau sont communs pour les corps plantaires du systme solaire et sont trs probables sur les exoplantes (plantes en dehors du systme solaire). Pour plusieurs objets du systmes solaire, leau de subsurface est prsente sous forme de glace. Pour la Terre et Mars, les zones satures de subsurface apparaissent travers toute leur histoire plantaire. La Terre est particulirement clmente avec la recharge des rservoirs, avec de amples prcipitations, des conditions glaciaires et de fortes chaleurs, comme latteste les enregistrements gologiques et palontologiques. Dun autre ct, Mars se trouve dans une phase essentiellement glaciaire, qui est interrompue par des activits contraintes par les phnomnes endogniques. Cette activit conduit de manire catastrophique des cycles hydrologiques et des perturbations climatiques brutaux. Les aquifres rgionaux dans les haute terres martiennes qui se sont forms dans des conditions similaires aux conditions terrestres, alimentent les plaines du Nord. Leau a galement t dplace vers le Ple Sud martien durant des changements marqus par une forte activit endognique et une modification des paramtres de lorbite de Mars. Venus possdait vraisemblablement une hydrosphre chaude durant des millions danne, avant le dveloppement de son atmosphre et sa surface particulirement chaude. Par aprs Venus a perdit son hydrosphre alors que la luminosit solaire augmentait et quune humidit lie un effet de serre sinstallait. Les ocans de subsurface deau ou deau ammoniacale, induits par les forces de mare et le chauffage radiognique, apparaissent probablement sur les satellites les plus importants (Europa, Ganymede, Callisto, Titan, Triton). Les forces de mare entre les petits corps externes du systme solaire peuvent galement occasionner la fusion de glace et la stabilit des ocans internes deau liquide.
Hydrogeology Journal 01/2005; 13(1):51-68. · 1.39 Impact Factor
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ABSTRACT: Several lines of evidence have recently reinforced the hypothesis that an ocean existed on early Mars. Carbonates are accordingly expected to have formed from oceanic sedimentation of carbon dioxide from the ancient martian atmosphere. But spectral imaging of the martian surface has revealed the presence of only a small amount of carbonate, widely distributed in the martian dust. Here we examine the feasibility of carbonate synthesis in ancient martian oceans using aqueous equilibrium calculations. We show that partial pressures of atmospheric carbon dioxide in the range 0.8-4 bar, in the presence of up to 13.5 mM sulphate and 0.8 mM iron in sea water, result in an acidic oceanic environment with a pH of less than 6.2. This precludes the formation of siderite, usually expected to be the first major carbonate mineral to precipitate. We conclude that extensive interaction between an atmosphere dominated by carbon dioxide and a lasting sulphate- and iron-enriched acidic ocean on early Mars is a plausible explanation for the observed absence of carbonates.
Nature 10/2004; 431(7007):423-6. · 36.28 Impact Factor
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ABSTRACT: Different-sized bodies of water have been proposed to have occurred episodically in the lowlands of Mars throughout the planet's history, largely related to major stages of development of Tharsis and/or orbital obliquity. These water bodies range from large oceans in the Noachian-Early Hesperian, to a minor sea in the Late Hesperian, and dispersed lakes during the Amazonian. To evaluate the more recent discoveries regarding the oceanic possibility, here we perform a comprehensive analysis of the evolution of water on Mars, including: 1. Geological assessment of proposed shorelines; 2. A volumetric approximation to the plains-filing proposed oceans; 3. Geochemistry of the oceans and derived mineralogies; 4. Post-oceanic (i.e., Amazonian) evolution of the shorelines; and 5. Ultimate water evolution on Mars.
02/2004;
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ABSTRACT: Ancient geologic/hydrologic phenomena on Mars observed through the magnetic data [1,2] provide windows to the ancient past through the younger Argyre and Hellas impacts [e.g., 3,4], the northern plains basement [5], and the Tharsis and Elysium magmatic complexes (recently referred to as superplumes [6,7]). These signatures, coupled with highly degraded macrostructures (tectonic features that are tens to thousands of km-long [8]), reflect an energetic planet during its embryonic development (.5 Ga or so of activity) with an active dynamo and magnetosphere [1,2,6]. One such window into the ancient past occurs northwest of the Hellas impact basin in Arabia Terra. Arabia Terra is one of the few water-rich equatorial regions of Mars, as indicated through impact crater [9] and elemental [10,11] information. This region records many unique traits, including stratigraphy, topography, cratering record, structural character, geomorphology, and geophysical, elemental, albedo, and thermal inertia signatures. We interpret these to collectively indicate a possible ancient giant impact basin that later became an important aquifer, as it provided yet another source of water for the formation of putative water bodies that occupied the northern plains [12,13] and addresses possible water-related characteristics that may be observed at the Opportunity landing site. This basin is antipodal to Tharsis and estimated to be at least 3,000 km in diameter.
02/2004;
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ABSTRACT: Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems [1], and the extremely flat northern plains topography at the distal reaches of these outflow channel systems.Basing on the ideas of episodic greenhouse atmosphere and water stability on the lowlands of Mars [3], a conceptual scheme for water evolution and associated geomorphologic features on the northern plains can be proposed. This model highlights Tharsis-triggered flood inundations and their direct impact on shaping the northern plains, as well as making possible the existence of fossil and/or extant life.Possible biologic evolution throughout the resulting different climatic and hydrologic conditions would account for very distinct metabolic pathways for hypothesized organisms capable of surviving and perhaps evolving in each aqueous environment, those that existed in the dry and cold periods between the flood inundations, and those organisms that could survive both extremes. Terrestrial microbiota, chemolithotrophic and heterotrophic bacteria, provide exciting analogues for such potential extremophile existence in Mars, especially where long-lived, magmatic-driven hydrothermal activity is indicated [14].
02/2003;
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ABSTRACT: Canali-type channels on Venus show inverted profile segments; that is, large portions of the channels trend uphill. The original gradients for these channels were not horizontal, but must have progressively trended downhill. Therefore, undulation patterns imposed on the profiles have to be the result of tectonism occurring since channel formation. This implies that some of the uppermost geological units of the plains, which are coincident with canali, experienced significant postemplacement tectonic deformation. The pattern of deformation is hierarchical. Within observational limits, at least two scales of deformation are indicated. The longer scale deformation (thousands of kilometers) corresponds to large-scale basins; the shorter scale deformation (hundreds of kilometers) corresponds to ridge belts or to small-scale domes/basins. The latter features, at scales up to a few hundred kilometers, extensively deform some plain areas. Although not appearing in the topographic profiles because of resolution limitations, deformation scales of tens of kilometers or less, which mostly reflect wrinkle ridges, also overlap the longer deformation scales. The channels probably formed relatively quickly in comparison to the time scale of deformation. Canali formation is closely related to the genesis of plains, and canali profile deformation reflects tectonic processes operating at multiple scales. The lower limit rates of large-scale tectonic warping are comparable to epeirogenetic deformation rates for Earth's intraplate continental interiors.
09/1994;
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ABSTRACT: Fluvial erosion on Mars has been nonuniform in both time and space.
Viking orbiter images reveal a variety of different aged terrains
exhibiting widely different degrees of erosion. Based on our terrestrial
analog studies, rates of fluvial erosion associated with the formation
of many of the valleys on Mars is probably on the order of hundreds of
meters per million years, while rates of erosion associated with the
formation of the outflow channels probably ranged from tens to hundreds
of meters in several weeks to months. However, estimated rates of
erosion of the Martian surface at the Viking Lander sites are extremely
low, on the order of 1 micron/yr or less. At most this would result in a
meter of material removed per million years, and it is unlikely that
such an erosion rate would be able to produce the degree of geomorphic
work required to form the fluvial features present elsewhere on the
surface. In addition, single terrain units are not eroded uniformly by
fluvial processes. Instead fluvial valleys, particularly in the cratered
highlands, typically are situated in clusters surrounded by vast
expanses of uneroded surfaces of the same apparent lithologic,
structural, and hydrological setting. Clearly throughout its geologic
history, Mars has experienced a nonuniformity in erosion rates. By
estimating the amount of fluvial erosion on dissected terrains and by
studying the spatial distribution of those locations which have
experienced above normal erosion rates, it should be possible to place
further constraints on Mars' paleoclimatic history.
02/1993; 24:587-588.
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ABSTRACT: Canali-type channels on Venus are unique because of their great lengths (up to 6800 km) and nearly constant channel cross sectional shapes along their paths. A simple model incorporating channel flow and radiative cooling suggests that common terrestrial-type tholeiite lava cannot sustain a superheated and turbulent state for the long distances required for thermal erosion of canali within allowable discharge rates. If canali formed mainly by constructional processes, laminar tholeiitic flow of relatively high, sustained discharge rates might travel the observed distances, but the absence of levees would need to be explained. An exotic low temperature, low viscosity lava like carbonatite or sulfur seems to be required for the erosional genesis of canali.
08/1992;
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ABSTRACT: Attention is given to Martian channels and valley networks, since they
have become a principal element of evidence to the effect that the
Martian atmosphere evolved from an early volatile-rich state to its
present condition. The outflow channels are relatively young, later
Hesperian or Amazonian in age. They formed by immense outbursts of fluid
from subsurface sources. Complexity in outflow-channel morphology was
generated by varying amounts of sediment and ice in the aqueous-fluid
flow systems. The overall cataclysmic-flood morphology may thus be
locally transitional to morphologies generated by ice and debris
flowage. Although local areas of valley networks, such as on Alba
Patera, formed coevally with outflow channel activity, regionally
extensive networks dominate in the heavily cratered terrains. The
morphology of many valleys suggests genesis by ground-water sapping; for
some valleys, surface runoff may have been more important.
Mars. 02/1992; -1:493-522.
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ABSTRACT: Medium (1:2,000,000) and high (1:500,000) resolution Viking images were used to locate, map, and analyze drainage systems of six moderate-sized Martian volcanoes of various ages (including Ceraunius Tholus, Hecates Tholus, Alba Patera, Hadriaca Patera, Apollinaris Patera, and Tyrrhena Patera) in order to determine the origin and the evolution of valley forms on these volcanoes. The morphological characteristics of the drainage forms were compared to those of terrestrial volcanic valleys of known origin. On the basis of studies of valleys on the Hawaiian volcanoes, an evolutionary sequence for valleys on the Martian volcanoes is proposed.
09/1990;
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ABSTRACT: Theoretical models of early Martian atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, earthlike fluvial valleys on the northern flank of Alba Patera conflicts with this scenario. Whereas the widespread ancient Martian valleys generally have morphologies indicative of sapping erosion by the slow outflow of subsurface water, the local Alba valleys were probably formed by surface-runoff processes. Because subsurface water flow might be maintained by hydrothermal energy inputs and because surface-runoff valleys developed late in Martian history, it is not necessary to invoke drastically different planet-wide climatic conditions to explain valley development on Mars. The Alba fluvial valleys can be explained by hydrothermal activity or outflow-channel discharges that locally modified the atmosphere, including precipitation and local overland flow on low-permeability volcanic ash.
11/1989;
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ABSTRACT: Work in progress on Hawaiian drainage evolution indicates an important potential for understanding drainage development on Mars. Similar to Mars, the Hawaiian valleys were initiated by surface runoff, subsequently enlarged by groundwater sapping, and eventually stabilized as aquifers were depleted. Quantitative geomorphic measurements were used to evaluate the following factors in Hawaiian drainage evolution: climate, stream processes, and time. In comparing regions of similar climate, drainage density shows a general increase with the age of the volcani island. With age and climate held constant, sapping dominated valleys, in contrast to runoff-dominated valleys, display the following: lower drainage densities, higher ratios of valley floor width to valley height, and more positive profile concavities. Studies of stream junction angles indicate increasing junction angles with time on the drier leeward sides of the major islands. The quantitative geomorphic studies and earlier field work yielded important insights for Martian geomorphology. The importance of ash mantling in controlling infiltration on Hawaii also seems to apply to Mars. The Hawaiian valley also have implications for the valley networks of Martian heavily cratered terrains.
06/1987;
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ABSTRACT: Channels and valleys were known on the Martian volcanoes since their discovery by the Mariner 9 mission. Their analysis has generally centered on interpretation of possible origins by fluvial, lava, or viscous flows. The possible fluvial dissection of Martian volcanoes has received scant attention in comparison to that afforded outflow, runoff, and fretted channels. Photointerpretative, mapping, and morphometric studies of three Martian volcanoes were initiated: Ceraunius Tholus, Hecate Tholus, and Alba Patera. Preliminary morphometric results indicate that, for these three volcanoes, valley junction angles increase with decreasing slope. Drainage densities are quite variable, apparently reflecting complex interactions in the landscape-forming factors described. Ages of the Martian volcanoes were recently reinterpreted. This refined dating provides a time sequence in which to evaluate the degradational forms. An anomaly has appeared from the initial study: fluvial valleys seem to be present on some Martian volcanoes, but not on others of the same age. Volcanic surfaces characterized only by high permeability lava flows may have persisted without fluvial dissection.
06/1987;
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ABSTRACT: Based on various lines of geologic, geomorphic, topographic, geophysical, spectral, and elemental evidence, we conclude that hydrothermal environments have certainly existed on Mars and are likely to still exist. Here, we present candidate targets of endogenic- and exogenic-driven hydrothermal environments on Mars based on a set of selection criteria and suggest strategies for the detection of such targets. This includes a re-evaluation of potential targets using both existing and yet-to-be-released remote information provided by the instruments onboard the Mars orbiters and rovers. We also provide terrestrial analogs for possible martian hydrothermal environments to highlight the implications of these targets for potential martian life. This compilation and synthesis of data from martian localities indicating hydrothermal activity is timely and a first step towards prioritizing candidate targets for further investigation, which will likely add more targets to this list. Future in situ exploration will have to focus on the most promising of the hydrothermal targets and investigate them utilizing a novel integrated multi-tier, multi-agent reconnaissance mission architecture.
Icarus.
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ABSTRACT: Nearly complete image coverage of Venus by Magellan enabled us to map various venusian channel and valley landforms and to examine their associations with other geological units. Global mapping reveals a nonrandom distribution. The highest total concentration is in the equatorial regions, characterized by highlands, rift and fracture zones, and associated volcanic features.Many channels associated with flow deposits are similar to typical terrestrial lava drainage channels. They are observed to be associated with a wide range of volcanic edifices, such as coronae, shield volcanoes, and rift and fracture zones. One type of channel, similar morphologically to lunar sinuous rilles, is classified as a venusian sinuous rille. Based on the close associations of many venusian sinuous rilles with coronae, we hypothesize that mantle plume or blob volcanism has caused high effusion and sustained lava eruptions essential for sinuous rille formation. Mantle-derived, high-temperature, low-viscosity lava eruptions are responsible for the efficient erosional processes, particularly for thermal erosion that seems to be, at least partially, required for some sinuous rille formation. Many valley networks are observed in highlands and in association with coronae. Fracture systems and source zones for low-viscosity lavas, both key to network formation, were probably concentrated at highlands and coronae. Canali-type channels, which are morphologically unlike other known volcanic channels, are limited to certain plains regions. A wide range of low-viscosity lava types is possible for the channel-forming lava, depending on the formation mechanism. Their lengths exceed the lengths of other common volcanic channel types on Venus, implying a large volume of lava and long duration of the eruption. The close association of canali with plains regions implies that canali formation is probably related to the emplacement of plains. A hypothesized global resurfacing event late in Venusian history may be responsible for canali formation.
Icarus.
