analysis of mola data for the mars exploration rover landing sites 1 we have used mars orbiter laser altimeter mola data to demonstrate that selected landing sites meet the mars exploration rover mer landing system topography and slope requirements at hectometer and kilometer scales to provide a comprehensive analysis we constrained slopes within each landing ellipse using four approaches 1 measurements of local slopes at 1 2 km length scales using both an adirectional maximum gradient method and a higher resolution bidirectional along track method 2 predictions of 100 m slopes using self affine statistics in conjunction with 3 calculations of both pulse width and slope corrected pulse width to constrain slopes at scales smaller than the mola spot size 180 m and 4 comparisons of simultaneously acquired mola data with mars orbiter camera data to identify the geomorphologic features associated with variations in observed slopes pulse width and for this analysis only reflectivity the results of the analysis indicate that the selected landing sites are consistent with the mer topography requirement of being below 1 3 km as well as having slopes less than 5 at length scales of 100 m and 2 at length scales of 1 2 km

acoustic elastic coupled equation for ocean bottom seismic data elastic reverse time migration abstractconventionally multicomponent geophones used to record the elastic wavefields in the solid seabed are necessary for ocean bottom seismic obs data elastic reverse time migration rtm particle velocity components are usually injected directly as boundary conditions in the elastic wave equation in the receiver side wavefield extrapolation step which causes artifacts in the resulting elastic images we have deduced a first order acoustic elastic coupled equation aece by substituting pressure fields into the elastic velocity stress equation evse aece has three advantages for obs data over evse when performing elastic rtm first the new equation unifies wave propagation in acoustic and elastic media second the new equation separates p waves directly during wavefield propagation third three approaches are identified when using the receiver side multicomponent particle velocity records and pressure records in elastic rtm processing 1 particle velocity components are set as boundary cond

meteorology of proposed mars exploration rover landing sites 1 a descriptive study of the near surface meteorology at three of the potential mars exploration rover mer landing sites terra meridiani gusev crater and melas chasma is presented using global and mesoscale models the mesoscale model provides a detailed picture of meteorology on scales down to a few kilometers but is not well constrained by observations away from the viking and pathfinder landing sites as such care must be taken in the interpretation of the results with there being high confidence that the types of circulations predicted will indeed occur and somewhat less in the quantitative precision of the predictions and the local time phasing of predicted circulations all three landing sites are in the tropics and are affected by hadley circulation by diurnal variations due to the global thermal tide and by planetary scale topography in these particular cases from tharsis elysium and the global topographic dichotomy boundary terra meridiani is least affected by large variations in local topography mean winds at terra meridiani during mer landing would be less than 10 m s with little vertical shear however these low wind speeds result from strong mixing in the early afternoon convective boundary layer which creates its own hazard in the horizontal variation of vertical winds of up to 8 m s both upward and downward in gusev crater the topography of ma adim vallis and the crater rim generates strong diurnally reversing channeling of wind in ma adim vallis and diurnally reversing radial flow in the crater associated with thermal slope winds on the crater rim the overturning circulation in gusev crater slightly suppresses the daytime convective boundary layer melas chasma in valles marineris provides an example of strong topographic forcing of near surface circulation of particular interest is the channeling of regional scale wind toward the center of the tharsis plateau during the evening this results in a surface level jet along the canyon of over 25 m s drainage of air from the plateau and into the canyon produces vertical winds down the canyon walls in the evening of over 5 m s in contrast during the early afternoon mer landing time horizontal winds at the proposed mer landing site are relatively calm with little mean shear with height this results from the proposed site being in a region of local divergence and the action of daytime convection the nature of flow in melas chasma results in an interesting dual maximum in boundary convection and depth with the usual daytime afternoon free convective maximum being joined by a mechanically forced nighttime boundary layer of almost 2 km depth

an unusual spectral unit in west candor chasma evidence for aqueous or hydrothermal alteration in the martian canyons abstract high spatial resolution observations made by orbiting spacecraft from the viking and phobos missions suggest the local development of crystalline ferric oxides in a small area in mars valles marineris canyon system quantitative color analysis of viking orbiter multispectral images identifies two spatially coherent regions of unique hue among the interior layered deposits in western candor chasma the anomalous color indicates a local compositional difference between these regions and the surrounding high albedo materials the unusual appearance of the unit in the viking color observations could be explained by a small increase in the degree of crystallinity or abundance of hematite near infrared spectra obtained by the ism imaging spectrometer aboard phobos 2 confirm a local enrichment in ferric oxides or oxyhydroxides in the region and suggest the presence of another phase in addition to hematite in high resolution the spectral unit can be seen to occur within two 20 km long depressions on the margins of an hesperian aged layered deposit which forms a plateau on the chasma floor water is implicated in the formation of the iron oxides since the same sedimentary layers seen in the depressions are exposed on steep surfaces elsewhere on the plateau but show no evidence of unusual coloration this suggests that the mineralization occurred through secondary alteration of preexisting rocks and developed locally in association with the depressions which could have ponded surface runoff or groundwater seepage

new models for the origin of valles marineris closed depressions current models for the formation of the abundant large closed depressions of valles marineris have serious shortcomings purely tectonic mechanisms are inconsistent with the morphology of many depressions and removal of large quantities of ground ice from the canyon walls is inconsistent with the observed strength of the walls accordingly we offer some alternatives one possibility involves decay of ice rich bodies occupying partially sediment choked ancient graben that predated the overlying cratered and ridged plains other possibilities involve the removal of massive equatorial carbonate deposits storing much of the planet s co2 inventory generated during greenhouse conditions on early mars solution by carbonic acid derived from the atmosphere analogous to terrestrial karst requires extensive recycling of the available water supply solution by various groundwater acids possibly derived from the tharsis magmas requires less water especially if only the smaller closed depressions are due to carbonate decay alternatively volume loss due to decarbonation of carbonate during early high heat flow or a later tharsis related heat pulse can produce extensive collapse especially if the carbonates have high silica content

new evidence for a magmatic influence on the origin of valles marineris mars in this paper we show that the complex geological evolution of valles marineris mars has been highly influenced by the manifestation of magmatism e g possible plume activity this is based on a diversity of evidence reported here for the central part melas chasma and nearby regions including uplift loss of huge volumes of material flexure volcanism and possible hydrothermal and endogenic induced outflow channel activity observations include 1 the identification of a new 50 km diameter caldera vent like feature on the southwest flank of melas which is spatially associated with a previously identified center of tectonic activity using viking data 2 a prominent topographic rise at the central part of valles marineris which includes melas chasma interpreted to mark an uplift consistent with faults that are radial and concentric about it 3 hirise identified landforms along the floor of the southeast part of melas chasma that are interpreted to reveal a volcanic field 4 crism identification of sulfate rich outcrops which could be indicative of hydrothermal deposits 5 grs k th signature interpreted as water magma interactions and or variations in rock composition and 6 geophysical evidence that may indicate partial compensation of the canyon and or higher density intrusives beneath it long term magma tectonic and water interactions late noachian into the amazonian albeit intermittent point to an elevated life potential and thus valles marineris is considered a prime target for future life detection missions

hematite bearing materials surrounding candor mensa in candor chasma mars implications for hematite origin and post emplacement modification abstract the valles marineris canyon system on mars is of enduring scientific interest in part due to the presence of interior mounds that contain extensive layering and water altered minerals such as crystalline gray hematite and hydrated sulfates the presence of hematite and hydrated sulfate minerals is important because their host rock lithologies provide information about past environments that may have supported liquid water and may have been habitable this work further defines the association and relationship between hematite bearing materials and low albedo presumably aeolian deposits and layered materials identifies physical characteristics that are strongly correlated with the presence of hematite and refines hypotheses for the origin and post emplacement modification including transport of these hematite bearing and associated materials there are only three regions surrounding candor mensa where hematite has been identified even though morphologic properties are similar throughout the entire mensa three possible explanations for why hematite is only exposed in these regions include 1 the topographic structure of the mensa walls concentrates hematite at the base of the layered deposits influencing the ability to detect hematite from orbit 2 the presence of differing amounts of dark mantling material and hematite free erosional sediment 3 the potential fracturing of the mensa and the influence of these structures on fluid flow and subsequent digenesis the observations of hematite bearing materials in this work support the hypothesis that hematite is eroding from a unit in the candor mensa interior layered deposits ild and is being concentrated as a lag deposit adjacent to the lower layers of candor mensa and at the base in the form of dark aeolian material due to the similar geologic context associated with hematite bearing and ild materials throughout the valles marineris canyon system the insight gained from studying these materials surrounding candor mensa can likely be applicable to similar layered deposits throughout valles marineris

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 volumes of deposits the central troughs north ophir north and central candor and north melas chasmata lie as much as 11 km below the adjacent plateaus in ophir and candor chasmata interior layered deposits reach 8 km in elevation if the deposits are lacustrine and if all troughs were interconnected lake waters standing 8 km high would have spilled out of coprates chasma onto the surrounding plateaus having surface elevations of only 4 5 km in this case interior deposits above about 4 km in the central troughs would not be lacustrine they could be volcanic on the other hand the troughs may not have been interconnected at the time of interior deposit emplacement they may have formed isolated ancestral basins the existence of such basins is supported by independent structural and stratigraphic evidence the ancestral basins may have eventually merged perhaps through renewed faulting to form northern subsidiary troughs in ophir and candor chasmata and the coprates north melas ius graben system the peripheral troughs are only 2 5 km deep shallower than the central troughs they may have formed from a combination of erosional collapse and structural activity chaotic terrain is seen in the peripheral troughs near a common contour level of about 4 km on the adjacent plateaus which supports the idea of release of water under artesian pressure from confined aquifers the layered deposits in the peripheral troughs may have formed in isolated depressions that harbored lakes and predated the formation of the deep outflow channels if these layered deposits are of volcanic origin they may have been emplaced beneath ice in the manner of table mountains areal and volumetric computations show that erosion widened the troughs by about one third and that deposits occupy one sixth of the interior space even though the volume eroded is larger than the volume deposited topographic and geologic considerations imply that material eroded from trough walls was probably part of the interior layered deposits but not their sole source additional material may have come from subterranean piping from reworking of local disintegration products on the floors such as chaotic materials or from eolian influx but overall it is likely that the additional material is volcanic and that it forms mostly the upper more diversely bedded layers of the interior deposits

high resolution thermal inertia derived from the thermal emission imaging system themis thermal model and applications 1 thermal inertia values at 100 m per pixel are determined using nighttime temperature data from the thermal emission imaging system themis on the mars odyssey spacecraft producing the highest resolution thermal inertia data set to date themis thermal inertia values have an overall accuracy of 20 a precision of 10 15 and are consistent with both thermal emission spectrometer orbital and miniature thermal emission spectrometer surface thermal inertia values this data set enables the improved quantification of fine scale surface details observed in high resolution visible images in the tharsis region surface textures and crater rims observed in visible images have no corresponding variation in the themis thermal inertia images indicating that the dust mantle is pervasive at themis scales and is a minimum of a few centimeters and up to 1 2 m thick the thermal inertia of bed form material indicates particle diameters expected for aeolian sediments and these materials are likely currently saltating variations in the thermal inertia within interior layered deposits in hebes chasma can be distinguished and the thermal inertia is too low to be consistent with bedrock or a lava flow thus a secondary emplacement of volcanic material or a volcanic ash deposit is a more likely method of formation higher resolution themis thermal inertia enables the identification of exposed bedrock on the martian surface in nili patera and ares vallis bedrock material corresponds to distinct compositional and morphologic surfaces indicating that a specific unit is exposed and is likely currently being kept free of unconsolidated material by aeolian processes

internal structure and early thermal evolution of mars from mars global surveyor topography and gravity topography and gravity measured by the mars global surveyor have enabled determination of the global crust and upper mantle structure of mars the planet displays two distinct crustal zones that do not correlate globally with the geologic dichotomy a region of crust that thins progressively from south to north and encompasses much of the southern highlands and tharsis province and a region of approximately uniform crustal thickness that includes the northern lowlands and arabia terra the strength of the lithosphere beneath the ancient southern highlands suggests that the northern hemisphere was a locus of high heat flow early in martian history the thickness of the elastic lithosphere increases with time of loading in the northern plains and tharsis the northern lowlands contain structures interpreted as large buried channels that are consistent with northward transport of water and sediment to the lowlands before the end of northern hemisphere resurfacing

postextensional mantle healing and episodic extension in the canning basin regions of the lithosphere that undergo finite crustal extension but are subsequently allowed to thermally relax during a period of reduced tectonic activity may become regions of relative strength and therefore resist any further extension the strengthening is a consequence of the temperature dependence of rock rheology and the local thinning of the crust bringing strong upper mantle olivine rich rocks closer to the surface where they replace weaker lower crustal plagioclase feldspar amphibole bearing rocks this concept which i call postextensional mantle healing is illustrated by the predictions of a numerical model although the model is based on the results of rock testing in the laboratory the results do not depend on a particular choice of creep parameters for the lower crust the palaeozoic tectonic history of the canning basin northwestern australia is characterized by a series of extensional episodes separated by periods of relative quiescence in this paper i suggest that postextensional mantle healing is responsible for the continuous shifting through time of tectonic activity between the several major depocenters the tectonic development of the east african rift system follows a scenario similar to that of the canning basin extensional structures inherited from two bursts of extension in the early mesozoic and cretaceous have not been reactivated during the tertiary rifting which is responsible for the present day rift morphology

structural development of coprates chasma and western ophir planum valles marineris rift mars a portion of valles marineris was mapped in detail in order to clarify the dominant processes responsible for the formation of coprates chasma new crater counts indicate that the caprock on western ophir planum plateau has a late hesperian crater age whereas trough floor preserved in western coprates chasma has an early to late hesperian crater age caprock on western ophir planum correlates in relative age with the syria planum formation and the caprock may overlie lower hesperian ridged plains material the conspicuous absence of wrinkle ridges on ophir planum may reflect burial by this later material trough floor material in coprates chasma correlates in relative age with ridged plains material on the adjacent lunae planum and coprates plateaus and represents a structurally coherent block displaced downward by normal faulting the crater counts and detailed structural relationships demonstrate the commonly accepted view that coprates chasma occupies a graben the floor of this graben is only thinly mantled by intratrough deposits and is relatively intact the trough shows no evidence for a chaotically broken and jumbled floor as required by genesis models of collapse and subsurface drainage formation of coprates chasma by keystone collapse of locally elevated topography is not supported by available topographic data but a general association between the trough and volcanotectonic activity in the tharsis region is considered to be a likely explanation for the trough forming stresses subtle asymmetries in topography and boundary fault development across coprates chasma may imply a gentle down to the north half graben geometry for the trough normal faults that define the northern margin of western coprates chasma and those that deform the adjacent ophir planum plateau change trend systematically with position implying a 30 rotation of the local horizontal principal stresses in this region during trough growth faulting on ophir planum appears related to the faulting that created the coprates chasma trough the geology and structure of coprates chasma are comparable to those of other troughs such as melas ius and perhaps candor chasmata suggesting that these troughs may also have formed as grabens the revised crater age for western ophir planum indicates that the initiation of trough faulting and subsidence in the valles marineris system is early late hesperian and may have been synchronous across the system relative to the prevailing cratering rate

meteorological predictions for 2003 mars exploration rover high priority landing sites 1 the mars regional atmospheric modeling system is used to predict meteorological conditions that are likely to be encountered by the mars exploration rovers at several proposed landing sites during entry descent and landing seven areas five of which contain specific high priority landing ellipses are investigated hematite two sites isidis planitia elysium planitia two sites valles marineris and gusev crater the last two locations are in regions of extreme topography and the local and regional thermal circulations that result are equally extreme horizontal wind speeds near the floor of valles marineris exceed 50 ms 1 vertical velocities near the walls exceed 40 ms 1 and penetrate 10 km in altitude above the rim of the canyon thermal convection is suppressed within valles marineris by subsidence that forms in response to the upslope flows along the canyon walls wind magnitudes at gusev crater are approximately one third of those at the canyon but horizontal wind shear is greater deep convective thermals are noted at the relatively flat hematite site where 10 ms 1 updrafts rising to heights of 5 km are not uncommon during the midafternoon linearly organized convective updrafts superimposed on upslope circulations dominate over most of isidis planitia hexagonal and linearly organized convection predominates at elysium planitia afternoon circulations at all sites pose some risk significant risk in some cases to entry descent and landing most of the atmospheric hazards are not evident in current observational data and general circulation model simulations and can only be ascertained through mesoscale modeling of the region

interior trough deposits on mars subice volcanoes widespread several kilometer thick successions of layered deposits occur as mounds that partly fill the troughs or chasmata that compose the valles marineris on mars like terrestrial subice volcanoes the layered deposits occur in a volcano tectonic setting within basins that may have held ponded water or ice on the basis of their dimensions morphologies and associated catastrophic floods and other geologic events as shown in viking and new mars global surveyor mgs data sets we suggest that the interior deposits are volcanic in origin and possibly generated by subice eruptions a tuya origin for the mounds can explain the lack of external sediment mound heights that can rival the plateau local flat topped mesas morphologically distinct mounds of different ages horizontal to steep dips fine grained materials indications of rare volcanic vents and lava flows and spectral composition the extremely diverse layering of west candor chasma and possible volcanic cones in melas may have formed by related subaerial eruptions consistent with the suggestion that interior deposits are eroding out of the wall rock some deposits could have been erupted from sites along the walls

selection of the mars exploration rover landing sites 1 the selection of meridiani planum and gusev crater as the mars exploration rover landing sites took over 2 years involved broad participation of the science community via four open workshops and narrowed an initial 155 potential sites 80 300 30 km to four finalists based on science and safety engineering constraints important to the selection included 1 latitude 10 n 15 s for maximum solar power 2 elevation less than 1 3 km for sufficient atmosphere to slow the lander 3 low horizontal winds shear and turbulence in the last few kilometers to minimize horizontal velocity 4 low 10 m scale slopes to reduce airbag spin up and bounce 5 moderate rock abundance to reduce abrasion or strokeout of the airbags and 6 a radar reflective load bearing and trafficable surface safe for landing and roving that is not dominated by fine grained dust the evaluation of sites utilized existing as well as targeted orbital information acquired from the mars global surveyor and mars odyssey three of the final four landing sites show strong evidence for surface processes involving water and appear capable of addressing the science objectives of the missions which are to determine the aqueous climatic and geologic history of sites on mars where conditions may have been favorable to the preservation of evidence of possible prebiotic or biotic processes the evaluation of science criteria placed meridiani and gusev as the highest priority sites the evaluation of the three most critical safety criteria 10 m scale slopes rocks and winds and landing simulation results indicated that meridiani and elysium planitia are the safest sites followed by gusev and isidis planitia

patterns of movement in rotational and translational landslides the movement of rotational and translational landslides occurs as a result of either sliding on discrete shear surfaces or ductile deformation within a shear zone in this paper we examine the movement histories of a number of landslides that occurred in a variety of materials in a range of settings and demonstrate that one of two movement styles is evident during accelerating phases for all landslides observed the first style which has previously been noted has a linear form in a plot of 1 v against time v is velocity the second style has an asymptotic form in the same plot trending toward steady state movement rates we propose that the linear form occurs in landslides in which crack propagation i e shear surface generation is the dominant process whereas the second style occurs where movement is taking place across existing planes of weakness or as a result of ductile deformation processes this study demonstrates that the evaluation of plots of 1 v against time for landslides is a useful technique for forecasting movement styles and rates and for interpreting ongoing deformation processes in real time

high resolution thermal inertia mapping from the mars global surveyor thermal emission spectrometer abstract high resolution thermal inertia mapping results are presented derived from mars global surveyor mgs thermal emission spectrometer tes observations of the surface temperature of mars obtained during the early portion of the mgs mapping mission thermal inertia is the key property controlling the diurnal surface temperature variations and is dependent on the physical character of the top few centimeters of the surface it represents a complex combination of particle size rock abundance exposures of bedrock and degree of induration in this work we describe the derivation of thermal inertia from tes data present global scale analysis and place these results into context with earlier work a global map of nighttime thermal bolometer based thermal inertia is presented at 1 4 per pixel resolution with approximately 63 coverage between 50 s and 70 n latitude global analysis shows a similar pattern of high and low thermal inertia as seen in previous viking low resolution mapping significantly more detail is present in the high resolution tes thermal inertia this detail represents horizontal small scale variability in the nature of the surface correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate to high thermal inertia and intermediate albedo this new unit has a modal peak thermal inertia of 180 250 j m 2 k 1 s 1 2 and a narrow range of albedo near 0 24 the unit covering a significant fraction of the surface typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material local 3 km resolution maps are also presented as examples of eolian fluvial and volcanic geology some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size outflow channels and valleys consistently show higher thermal inertias than the surrounding terrain generally correlations between spatial variations in thermal inertia and geologic features suggest a relationship between the hundred meter scale morphology and the centimeter scale surface layer

fluvial and lacustrine activity on layered deposits in melas chasma valles marineris mars 1 valley networks on mars are the most obvious features attesting that different geologic processes and possibly climatic conditions existed in the past themis images reveal valley networks within melas chasma in valles marineris a hesperian age canyon system the valley networks in melas chasma are dense and highly organized and the heads of the valleys are scattered at different elevations all these features suggest that the networks were fed by precipitation the morphological details reveal inner channels on some valley floors attesting that water flowed within these valleys on the dem the valleys flow into a completely enclosed depression the edge of this feature follows a mola contour line and the depression shows many sedimentary morphologies suggesting lacustrine environment these landforms are located on remnants of layered deposits possibly composed of sulfate layers suggesting that fluvial activity could have contributed to the erosion of the layered terrains in valles marineris collectively the features in melas chasma are a maximum of hesperian in age these results suggest that warm wet environmental conditions on mars persisted through the hesperian and were present during the formation of valles marineris the evidence for a paleolake in melas chasma attests to adequate environmental conditions for life development through the hesperian period

a giant landslide on the north flank of tenerife canary islands the extent of mass wasting along the north flank of tenerife has been mapped using swath bathymetry gloria side scan sonar and 3 5 khz echo sounder data the marine surveys show that north of tenerife a giant landslide is exposed over an area of 5500 km2 of the seafloor more than twice the surface area of the island the landslide truncates an older ridge and valley topography that is associated with the shield building basalts on tenerife we interpret the ridge and valley topography as the result of subaerial erosion the landslide is estimated to have a length of 100 km a width of up to 80 km and a volume of about 1000 km3 it extends onshore into the orotava and icod valleys which have been interpreted as of landslide origin k ar dating of basaltic flows in the steep headwall of orotava suggests an age of formation for the valley is younger than 0 78 ma and may even be younger than 0 27 ma the icod valley is located immediately to the north of the most recent volcano on tenerife las canadas and has been associated with the collapse of its caldera between 1 2 and 0 2 ma a young age for the landslide is supported by the 3 5 khz echo sounder data which show that the landslide is draped by a thin 10 m layer of younger sediment the landslide did not form however during a single catastrophic event but represents the amalgamation of a number of separate landslides the occurrence of the ridge and valley topography in water depths of up to 2 5 km suggests that the shield building basalts have subsided by at least this amount since they formed 3 3 8 0 ma we speculate that this subsidence is caused by some form of stress relaxation that occurs in the underlying lithosphere the giant landslide imaged in our sonar data is associated with the late stages in the development of the most recent volcano on tenerife las canadas which only began at about 1 8 ma thus landsliding may be a particular feature of the time soon after emplacement when because of incomplete isostatic adjustment oceanic volcanoes have their greatest elevations above sea level and therefore are most susceptible to slope failure

an empirical approach to studying debris flows implications for planetary modeling studies 1 high resolution images acquired by the mars global survey mars orbiter camera show gullies on the walls of impact craters and valley systems on mars depositional aprons associated with these gullies have been interpreted by malin and edgett 2000 to be characteristic of debris flow and to indicate the presence of sources of liquid water at shallow depths below the martian surface by focusing on a terrestrial debris flow we test the application of chezy type modeling to provide more direct estimates of the dynamics of proposed debris flows on mars traditionally planetary scientists constrained by available remotely sensed data have used a range of flow models to gain insights from deposits into the behavior and rheologic nature of features such as lava flows debris flows and gravity driven flows on the basis of these model results broad interpretations of the physics governing flows of granular materials have been tempting based on limited field derived data this study tests and validates the extent to which the absolute value and relative variations of empirical parameters derived from the chezy type models describe the behavior of the general s slide debris flow 38 24 n 78 23 w in madison county virginia the results indicate that extreme caution must be taken when interpreting model results for turbulent flows of granular materials we obtained high precision topographic profiles superelevation data sedimentary facies and sedimentary textural properties over the debris flow this study focuses on the empirical parameter c whose value gauges energy dissipation in a flow thereby called flow resistance using field observations both variations and absolute values of c along the debris flow have been computed using two approaches 1 assuming constant volumetric flow rate q where only topography and high resolution images are required to compute channel dimensions and 2 a variable q calculated using field derived data assuming near newtonian flow conditions in the debris flow estimated values of c range from 0 035 to 0 099 when q is fixed c decreases as a function of distance downstream when q varies and c is computed from field derived flow speeds its value tends to increase downstream slightly these opposite results have been compared to the field observations to determine which best describes the behavior of the flow the variations in c downstream obtained using the flow speeds are most consistent with the geomorphic evidence for erosion of material by the debris flow and the presence of bends in the channel the average values of c 0 036 0 33 for the general s slide have been compared with computed c values for newtonian and near newtonian flows to assess the rheology of the flow during emplacement our terrestrial study demonstrates that advances in understanding of the dynamics of debris flows on the mars depends on obtaining debris flow speeds in addition to channel topography and flow thickness rather than just on channel topography flow thickness and the assumption that q is constant mars orbiter camera moc and mars observer laser altimeter mola data can be used to derive channel topography flow thickness and possibly flow speeds such data will provide more direct estimates of the dynamics of debris flows on mars than are currently available

mantled and exhumed terrains in terra meridiani mars 1 hematite bearing deposits in the terra meridiani region of mars constitute the top stratum of a partially eroded layered complex that covers dissected noachian aged cratered terrain the hematite unit consists of dark plains and dunes covering a bright substrate this substrate is fully exposed beyond the borders of the hematite bearing deposit and consists of polygonal ground separated by ridges or valleys together with layered deposits that have been eroded into a variety of landforms the complex is partially covered by a regional scale aeolian mantle that thickens toward the north the hematite bearing stratum exhibits low albedoes pulse widths and intermediate thermal inertias whereas the underlying unit exhibits high values of these parameters both units have spectral emissivity signatures similar to those for the low albedo cratered terrain to the south with the addition of hematite for the top stratum the complex is interpreted to consist of extensive plains forming lava flows and tephra deposits emplaced during an extensional regime and at least partially buried by an aeolian mantle aeolian stripping of the mantle exposed much of the complex and differentially eroded the deposits to produce the landforms existent today exploration of the hematite bearing deposits by the 2003 mars exploration rover opportunity will allow testing of the hypotheses presented since this stratum has been locally reworked into dunes that only partially cover the underlying brighter portion of the complex in particular the rover based measurements will allow us to test the extent to which the unusual remote sensing properties of the units indicate aqueous alteration

valles marineris mars wet debris flows and ground ice abstract detailed study of the valles marineris equatorial troughs suggests that the landslides in that area contained water and probably were gigantic wet debris flows one landslide complex generated a channel that has several bends and extends for 250 km further support for water or ice in debris masses includes rounded flow lobes and transport of some slide masses in the direction of the local topographic slope differences in speed and emplacement efficiency between martian and terrestrial landslides can be attributed to the entrainment of volatiles on mars but they can also be explained by other mechanisms support that the wall rock contained water comes from the following observations 1 the water within the landslide debris must have been derived from wall rock 2 debris appears to have been transported through tributary canyons 3 locally channels emerged from the canyons 4 the wall rock apprarently disintegrated and flowed easily and 5 fault zones within the troughs are unusually resistant to erosion the study further suggests that in the equatorial region of mars material below depths of 400 800 m was not desiccated during the time of landslide activity within the last billion years of martian history therefore the martian ground water or groundice reservoir if not a relic from ancient times must have been replenished

athena mars rover science investigation 1 each mars exploration rover carries an integrated suite of scientific instruments and tools called the athena science payload the primary objective of the athena science investigation is to explore two sites on the martian surface where water may once have been present and to assess past environmental conditions at those sites and their suitability for life the remote sensing portion of the payload uses a mast called the pancam mast assembly pma that provides pointing for two instruments the panoramic camera pancam and the miniature thermal emission spectrometer mini tes pancam provides high resolution color stereo imaging while mini tes provides spectral cubes at mid infrared wavelengths for in situ study a five degree of freedom arm called the instrument deployment device idd carries four more tools a microscopic imager mi for close up imaging an alpha particle x ray spectrometer apxs for elemental chemistry a mossbauer spectrometer mb for the mineralogy of fe bearing materials and a rock abrasion tool rat for removing dusty and weathered surfaces and exposing fresh rock underneath the payload also includes magnets that allow the instruments to study the composition of magnetic martian materials all of the athena instruments have undergone extensive calibration both individually and using a set of geologic reference materials that are being measured with all the instruments using a mer like rover and payload in a number of field settings we have devised operations processes that will enable us to use the mer rovers to formulate and test scientific hypotheses concerning past environmental conditions and habitability at the landing sites

low albedo surfaces and eolian sediment mars orbiter camera views of western arabia terra craters and wind streaks 1 high spatial resolution 1 5 to 6 m pixel mars global surveyor mars orbiter camera images obtained september 1997 to june 2001 show that each of the large dark wind streaks of western arabia terra originate at a barchan dune field on a crater floor the streaks consist of a relatively thin 1 m coating of sediment deflated from the dune fields and their vicinity in most cases this sediment drapes over a previous mantle that more thickly covers nearly all of western arabia terra no concurrent eolian bedforms are found within the dark streaks nor do any dunes climb up crater walls to deliver sand via saltation to the streaks the relations between dunes wind streak and subjacent terrain imply that dark toned grains finer than those that comprise the dunes are lifted into suspension and carried out of the craters to be deposited on the adjacent terrain previous eolian physics and thermal inertia studies suggest that under modern martian conditions such grains likely include silt 3 9 62 5 m very fine sand 62 5 125 m and possibly fine sand to 210 m the streaks change in terms of extent relative albedo and surface pattern over periods measured in years however through june 2001 very little evidence for recent eolian activity dust plumes storms dune movement was observed

mars exploration rover candidate landing sites as viewed by themis the analysis of six landing sites that were candidates for the two nasa mars exploration rovers mer benefited from recently available image data from the thermal emission imaging spectrometer themis onboard the 2001 mars odyssey spacecraft the combination of daytime and nighttime thermal infrared images from themis supplemented by additional data sets has lead to new or expanded insights into the nature of each landing site in meridiani planum a layer of lighter toned higher thermal inertia material is observable just below the hematite bearing layer gusev crater displays a more complex stratigraphy than previously observed including an upper layer with lobate margins the highest inertia unit of southern isidis planitia is confined to topographic lows in the rim basin margin and does not appear to be due to highland material transported onto the basin floor the enigmatic ovoid blocky terrain on the floor of melas chasma displays higher thermal inertia than its surroundings an indication that it contains coarser or more indurated material than the adjacent aeolian bedforms the myriad channels of athabasca valles display distinctive thermal signatures despite the presence of a bright layer of dust covering the region the presence of alluvial fans produced from spur and gulley erosion of the walls of eos chasma demonstrates that mass movements have occurred following the canyon scouring floods

high resolution topomapping of candidate mer landing sites with mars orbiter camera narrow angle images 1 we analyzed narrow angle mars orbiter camera moc na images to produce high resolution digital elevation models dems in order to provide topographic and slope information needed to assess the safety of candidate landing sites for the mars exploration rovers mer and to assess the accuracy of our results by a variety of tests the mapping techniques developed also support geoscientific studies and can be used with all present and planned mars orbiting scanner cameras photogrammetric analysis of moc stereopairs yields dems with 3 pixel typically 10 m horizontal resolution vertical precision consistent with 0 22 pixel matching errors typically a few meters and slope errors of 1 3 these dems are controlled to the mars orbiter laser altimeter mola global data set and consistent with it at the limits of resolution photoclinometry yields dems with single pixel typically 3 m horizontal resolution and submeter vertical precision where the surface albedo is uniform the dominant error is 10 20 relative uncertainty in the amplitude of topography and slopes after calibrating photoclinometry against a stereo dem to account for the influence of atmospheric haze we mapped portions of seven candidate mer sites and the mars pathfinder site safety of the final four sites elysium gusev isidis and meridiani was assessed by mission engineers by simulating landings on our dems of hazard units mapped in the sites with results weighted by the probability of landing on those units summary slope statistics show that most hazard units are smooth with only small areas of etched terrain in gusev crater posing a slope hazard

comparison of flat topped stellate seamounts on earth s seafloor with stellate domes on venus using side scan sonar and magellan synthetic aperture radar abstract the diameters of many domes on venus imaged by the magellan synthetic aperture radar sar are an order of magnitude larger than terrestrial subaerial domes however surveys of the seafloor using sonar imaging systems such as gloria geological long range inclined asdic and seabeam have revealed flat topped volcanic features with similar diameters volumes and slope angles suggested analogies between domes on venus and seamounts on the northern east pacific rise and off hawaii have been tested by d k smith j volcanol geotherm res 73 1996 47 64 using comparisons of size and shape and significant differences identified gloria images of flat topped seamounts near hawaii show them to have stellate planforms over half of the total population of 375 domes on venus have been modified and many have stellate planforms we have focused on the similarities in stellate planforms between flat topped seamounts and modified domes on venus we have used gloria sonar and magellan radar data to constrain the formation and evolution of both flat topped seamounts on the ocean floor and volcanic domes on venus to see if the processes that formed them are similar we propose that flat topped seamounts on the hawaiian ridge are built on sediments overlying the oceanic crust and that available evidence supports three processes that can form stellate margins 1 radial dike intrusions related to flank rift zones 2 dike intrusions which cause slope failures and 3 gravitational slope failures unrelated to intrusions for venus where low erosion rates and the absence of a sediment layer results in lavas being emplaced directly onto the crust the available evidence supports stellate margins originating by gravitational slope failures unrelated to diking though intrusions cannot be ruled out with existing data

geology of the melas chasma landing site for the mars exploration rover mission 1 the melas chasma landing site was considered a high priority site for the mars exploration rover mer mission because of the opportunity to land on and study potential layered sedimentary deposits though no longer considered a candidate site because of safety concerns the site remains a scientifically interesting area that provides insight into the geologic history of valles marineris within the landing ellipse are dunes landslide material and unusual blocky deposits the blocky deposits are composed of rounded blocks some of which have meter scale layering and they show evidence of ductile deformation including bending and distortion of coherent blocks around each other the morphologic characteristics of the blocks are unique and they appear to have no terrestrial analogue however the gross morphology of these blocky deposits and their superposition on adjacent wallrock is consistent with the blocks having been transported downslope given the existence of other large mass failures in the area we propose the blocky deposits may also have originated from mass movement events the size of the blocks coupled with the distances they traveled indicates high mobility the distances the blocks were transported and their rounded irregular shapes suggest either water in the source material or deposition in a subaqueous environment the source for the main blocky deposit inside the landing ellipse is considered to be the wallrock to the south while the other two blocky deposits have source regions along the northern canyon walls the southern wallrock of melas chasma contains numerous valleys not seen elsewhere in valles marineris the identification of valley networks along the southern wallrock suggests that a source of water existed below the surface of the plateau and produced the valleys after intersecting the edge of the exposed canyon walls

analysis of atmospheric mesoscale models for entry descent and landing 1 each mars exploration rover mer is sensitive to the martian winds encountered near the surface during the entry descent and landing edl process these winds are strongly influenced by local mesoscale conditions in the absence of suitable wind observations wind fields predicted by martian mesoscale atmospheric models have been analyzed to guide landing site selection in order to encompass the available models and render them useful to the edl engineering team a series of statistical techniques was applied to the model results these analyses cover the high priority landing sites during the expected landing times 1200 1500 lt the number of sites studied is limited by the computational and analysis cost of the mesoscale models the statistical measures concentrate on the effective mean wind the wind as seen by the landing system and on the vertical structure of the horizontal winds both aspects are potentially hazardous to the mer landing system in addition a number of individual wind profiles from the mesoscale model were processed into a form that can be used directly by the edl monte carlo simulations the statistical analysis indicates that the meridiani planum and elysium landing sites are probably safe the gusev crater and isidis basin sites may be safe but further analysis by the edl engineers will be necessary to quantify the actual risk finally the winds at the melas chasma landing site and presumably other valles marineris landing sites are dangerous while the statistical parameters selected for these studies were primarily of engineering and safety interest the techniques are potentially useful for more general scientific analyses one interesting result of the current analysis is that the depth of the convective boundary layer and thus the resulting energy density appears to be primarily driven by the existence of a well organized mesoscale or regional circulation primarily driven by large scale topographic features at mars

relative age of interior layered deposits in southwest candor chasma based on high resolution structural mapping high resolution topography generated from stereo hirise high resolution imaging science experiment imagery reveals the meter scale structure of interior layered deposits ild in southwest candor chasma this study seeks to determine the age of the local ild relative to any normal faults that can be attributed to chasma formation the study area is located near the contact of these ild and the wall rock and is in an area where chasma forming normal faults have been proposed we find that while normal faults are found in the study area these faults are not sufficiently large nor appropriately located or oriented to accommodate the roughly northeast southwest extension that is required for normal faults that can be attributed to chasma formation additionally bedding exposed in the local ild generally dips toward the center of candor chasma consistent with sediment deposition in a preexisting basin further pit craters of tithonia catena presumed to predate or be contemporaneous with the formation of west candor chasma do not cut into the ild within the study area these independent lines of evidence support a postchasma age for the ild exposed within the study area chasma related normal faults may exist within these ild at depth but are not exposed at the surface approximately 2 km of conformable stratigraphy is exposed in the study area and therefore at least several kilometers of the local ild were deposited subsequent to any chasma related normal faulting that may have occurred in this part of candor chasma

stratigraphy and erosional landforms of layered deposits in valles marineris mars the complex stratigraphy of layered deposits suggests a diversity of origins ages and post depositional modification histories the complexities within some layered deposits indicate changes in the dominant source materials in space and time the stratigraphy of layered deposits in the isolated martian chasmata hebes juventae and gangis is not well correlated this indicates that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences separated layered deposits in ophir candor and melas chasmata might have been a single continuous deposit in each chasma chaotic terrains are found in conjunction with layered deposits in juventae gangis and capri eos chasmata in these chasmata layered deposits unconformably overlie chaotic terrains chaotic terrain formation may have provided water to form paleolakes and lacustrine deposition of thick layered deposits may have occurred if the canyons were closed a very thick sequence of the layered deposits has been exposed by erosion a combination of gradual processes such as evaporation of ice and eolian and fluvial transport in addition to structural processes may be responsible for this erosion another alternative is that catastrophic water release under the layered deposits disrupted and initiated erosion of the layered deposits newly identified units of anomalous color are confined to the depressions or reentrants in western candor chasma the difference in color between these units and the surrounding terrain is most consistent with a somewhat greater content of bulk crystalline hematite in these anomalous units the presence of the candor units is a result of original and or secondary deposition which is different from the primary and dominant formation of the layered deposits

a new hematite formation mechanism for mars the origin of hematite detected in martian surface materials is commonly attributed to weathering processes or aqueous precipitation here we present a new hematite formation mechanism that requires neither water nor weathering glass rich basalts with martian meteorite like chemistry high feo low al2o3 oxidized at high 700 and 900 c temperatures in air and co2 respectively form thin 1 m hematite coatings on their outermost surfaces hematite is manifested macroscopically by development of magnetism and a gray metallic sheen on the glass surface and microscopically by fe enrichment at the glass surface observed in element maps visible and nearinfrared thermal infrared and raman spectroscopy confirm that the fe enrichment at the oxidized glass surfaces corresponds to hematite mineralization hematite formation on basaltic glass is enabled by a mechanism that induces migration of fe2 to the surface of an oxidizing glass and subsequent oxidation to form hematite a natural example of the hematite formation mechanism is provided by a hawaiian basalt hosting a gray metallic sheen that corresponds to a thin hematite coating hematite coating development on the hawaiian basalt demonstrates that martian meteorite like feo contents are not required for hematite coating formation on basalt glass and that such coatings form during initial extrusion of the glassy basalt flows if gray hematite originating as coatings on glassy basalt flows is an important source of martian hematite which is feasible given the predominance of igneous features on mars then the requirement of water as an agent of hematite formation is eliminated

wind driven erosion and exposure potential at mars 2020 rover candidate landing sites aeolian processes have likely been the predominant geomorphic agent for most of mars history and have the potential to produce relatively young exposure ages for geologic units thus identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions such as the mars 2020 rover mission that aims to explore astrobiologically relevant ancient environments here we investigate wind driven activity at eight mars 2020 candidate landing sites to constrain erosion potential at these locations to demonstrate our methods we found that contemporary dune derived abrasion rates were in agreement with rover derived exhumation rates at gale crater and could be employed elsewhere the holden crater candidate site was interpreted to have low contemporary erosion rates based on the presence of a thick sand coverage of static ripples active ripples at the eberswalde and southwest melas sites may account for local erosion and the dearth of small craters moderate flux regional dunes near mawrth vallis were deemed unrepresentative of the candidate site which is interpreted to currently be experiencing low levels of erosion the nili fossae site displayed the most unambiguous evidence for local sand transport and erosion likely yielding relatively young exposure ages the downselected jezero crater and northeast syrtis sites had high flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses both sites had relatively high estimated abrasion rates which would yield young exposure ages the downselected columbia hills site lacked evidence for sand movement and contemporary local erosion rates are estimated to be relatively low

mobility of large rock avalanches evidence from valles marineris mars measurements of h l height of drop length of runout vs volume for landslides in valles marineris on mars show a trend of decreasing h l with increasing volume this trend which is linear on a log log plot is parallel to but lies above the trend for terrestrial dry rock avalanches this result and estimates of 10 4 to 10 5 pa yield strength suggest that the landslides were not water saturated as suggested by previous workers the offset between the h l vs volume trends shows that a typical martian avalanche must be nearly two orders of magnitude more voluminous than a typical terrestrial avalanche in order to achieve the same mobility this offset might be explained by the effects of gravity on flows with high yield strengths these results should prove useful to future efforts to resolve the controversy over the mechan ics of long runout avalanches

surficial geologic surveys of gale crater and melas chasma mars integration of remote sensing data abstract remote sensing observations of gale crater and melas chasma are synthesized to better understand the present surface layer in these two scientifically interesting regions data sets analyzed include geologic maps mars orbiter laser altimeter mola elevation thermal emission spectrometer tes albedo tes thermal inertia mola residual pulse width tes rock abundance and viking and mars orbiter camera images using these data sets we constrain the properties of and processes acting on the present surface and create self consistent models for the surface layer surface properties within gale crater are variable and complex and interpreting the surface layer is not straightforward observations indicate that aeolian processes have shaped some of the intracrater surface but other areas do not comply with this model and have counterintuitive surface characteristics in contrast aeolian activity appears to have played a large role in shaping the present day physical structure of all surfaces in melas chasma and is reflected in the remote sensing data sets here we summarize our analysis and discuss the surface attributes as determined from these data sets

rheologic properties and kinematics of emplacement of the chaos jumbles rockfall avalanche lassen volcanic national park california the chaos jumbles is a rockfall avalanche deposit that was emplaced by three separate events 300 years ago deposits from each event are distinguishable on the basis of morphology size variation of large dacitic surface clasts and by the color of both the matrix and entrained dacitic blocks steep lateral and distal deposit margins and surface features such as folds and apparent strike slip faults indicate that each rockfall avalanche had a finite yield strength and was being actively deformed and sheared throughout the body of the moving deposit rather than strictly along a basal surface kinematic analysis of the three deposits indicates that each had a very low apparent coefficient of friction and was emplaced at velocities of up to 100 m s these data suggest that each rockfall avalanche can be modeled as a pseudoplastic material undergoing flow parallel compression above a frictionless base this model allows calculation of deposit volumes ranging from 1 2 to 1 7 108 m3 and also suggests that a future rockfall avalanche from the same location would have a more restricted runout than the previous events

prodigious submarine landslides on the hawaiian ridge the extensive area covered by major submarine mass wasting deposits on or near the hawaiian ridge has been delimited by systematic mapping of the hawaiian exclusive economic zone using the side looking sonar system gloria these surveys show that slumps and debris avalanche deposits are exposed over about 100 000 km2 of the ridge and adjacent seafloor from kauai to hawaii covering an area more than 5 times the land area of the islands some of the individual debris avalanches are more than 200 km long and about 5000 km3 in volume ranking them among the largest on earth the slope failures that produce these deposits begin early in the history of individual volcanoes when they are small submarine seamounts culminate near the end of subaerial shield building and apparently continue long after dormancy consequently landslide debris is an important element in the internal structure of the volcanoes the dynamic behavior of the volcanoes can be modulated by slope failure and the structural features of the landslides are related to elements of the volcanoes including rift zones and fault systems the landslides are of two general types slumps and debris avalanches the slumps are slow moving wide up to 110 km and thick about 10 km with transverse blocky ridges and steep toes the debris avalanches are fast moving long up to 230 km compared to width and thinner 0 05 2 km they commonly have a well defined amphitheater at their head and hummocky terrain in the lower part oceanic disturbance caused by rapid emplacement of debris avalanches may have produced high level wave deposits such as the 365 m elevation hulopoe gravel on lanai that are found on several islands most present day submarine canyons were originally carved subaerially in the upper parts of debris avalanches subaerial canyon cutting was apparently promoted by the recently steepened and stripped slopes of the landslide amphitheaters

young volcanic deposits in the valles marineris mars abstract 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 interior beds warping faulting erosion and landslide emplacement the young deposits are of three major types 1 dark patches typically occurring along faults 2 light colored deposits locally associated with craters and 3 rugged mottled deposits with in places light colored lobate fronts these young materials may be of volcanic origin as suggested by the low albedo and spectrally gray colors of some their association with faults and possible volcanic craters and calderas and their embayment relations and lobate margins no other mechanism explains all the observed features and relations as well as volcanism if these deposits are volcanic implications are that 1 volcanism was associated with rifting in the valles marineris 2 the volcanism was explosive in places and 3 the volcanism may be as young as the late tharsis volcanism and locally may well be recent

origin and evolution of the layered deposits in the valles marineris mars abstract thick sequences of layered deposits are found in the martian valles marineris they exhibit fine nearly horizontal layering and are present as isolated plateaus of what may have once been more extensive deposits individual sequences of layered deposits are as thick as 5 km the greatest total thicknesses of deposits are found in candor ophir and melas chasmata individual layer thicknesses range from about 70 to 300 m some tilting of sequences is observed but at the best image resolutions no angular unconformities are detectable in the layers the sequences of events in the canyons as deduced from morphologic and stratigraphic evidence was 1 graben formation in response to the tharsis uplift 2 canyon wall retreat and canyon enlargement roughly contemporaneous with formation of the layered deposits 3 deep erosion of the layered deposits 4 landsliding of the canyon walls and 5 eolian erosion of the layered deposits perhaps continuing up to the present we consider four hypotheses for the origin of the layered deposits they are eolian deposits they are remnants of the material that makes up the canyon walls they are deposits of explosive volcanic eruptions or they were deposited in standing bodies of water the rhythmic nature of the layers and their lateral continuity horizontality great thickness and stratigraphic relationships with other units in the canyons all appear most consistent with deposition in an aqueous environment if standing bodies of water existed in the valles marineris they were almost certainly ice covered there are three ways in which sediment could have entered an ice covered lake down through the ice cover up from the lake bottom or in from the lake margins layers of sediment could have been transported downward through an ice cover by foundering or rayleigh taylor instabilities but it is not clear whether there was a viable mechanism for repeatedly accumulating thick sediment layers on top of the ice cover subaqueous volcanic eruption on the lake bottom does not suffer from many of the morphologic arguments that make origin by subaerial volcanism seem improbable while this mechanism is attractive there are no eruptive centers observed and there is no other direct evidence to support it because canyon enlargement took place at roughly the same time as layer deposition debris from the canyon walls is an obvious and likely source for some of the material in the layered deposits however the volume of material removed from the canyon walls may be insufficient to account for all of the presently observed material we conclude that there are several geologically feasible but as yet unproven mechanisms that could have led to formation of thick deposits in ice covered paleolakes in the valles marineris present data are insufficient to choose conclusively among the various possibilities several types of data from the mars observer mission will be useful in further characterizing the deposits and clarifying the process of their origin the deposits should be considered important targets for a future mars sample return mission

end member identification and spectral mixture analysis of crism hyperspectral data a case study on southwest melas chasma mars we present spectral unmixing results over the southwest melas chasma region where a variety of hydrated minerals were identified we use the disort radiative transfer model to simultaneously model mars atmospheric gases aerosols and surface scattering and retrieve the single scattering albedos ssas modeled by the hapke bidirectional scattering function from crism data we employ a spectral unmixing algorithm to quantitatively analyze the mineral abundances by modeling the atmospherically corrected crism ssas using a non negative least squares nnls linear deconvolution algorithm to build the spectral library used for spectral unmixing we use the factor analysis and target transformation fatt technique to recover spectral end members within the crism scenes we investigate several distinct geologic units including an interbedded poly and monohydrated sulfate unit interbedded unit 1 and an interbedded phyllosilicate sulfate unit interbedded unit 2 our spectral unmixing results indicate that polyhydrated sulfates in the interbedded unit 1 have a much lower abundance 10 than that of the surrounding unit 20 and thus may have been partially dehydrated into kieserite to form the interbedded strata supporting a two staged precipitation dehydration formation hypothesis in the interbedded unit 2 phyllosilicates have an abundance of 40 and are interbedded with 20 sulfates the results in combination with thermodynamic calculations performed previously suggest that the interbedded phyllosilicates and sulfates likely formed through coupled basalt weathering and evaporation the methodology developed in this study provides a powerful tool to derive the mineral abundances aiming to better constrain the formation processes of minerals and past aqueous environment on mars

identification distribution and possible origins of sulfates in capri chasma mars inferred from crism data crism is a hyperspectral imager onboard the mars reconnaissance orbiter mro nasa 2005 which has been acquiring data since november 2006 and has targeted hydrated minerals previously detected by omega mars express esa 2003 the present study focuses on hydrated minerals detected with crism at high spatial resolution in the vicinity of capri chasma a canyon of the valles marineris system crism data were processed and coupled with mro and other spacecraft data in particular hirise high resolution science experiment mro images detections revealed sulfates in abundance in capri especially linked to the interior layered deposits ild that lie in the central part of the chasma both monohydrated and polyhydrated sulfates are found at different elevations and are associated with different layers monohydrated sulfates are widely detected over the massive light toned cliffs of the ild whereas polyhydrated sulfates seem to form a basal and a top layer associated with lower albedo deposits in flatter areas hydrated silicates phyllosilicates or opaline silica have also been detected very locally on two mounds about a few hundred meters in diameter at the bottom of the ild cliffs we suggest some formation models of these minerals that are consistent with our observations