limnologic analysis of gusev crater paleolake mars abstract the survey of the hydrogeologic system formed by gusev crater and ma adim vallis aeolis subquadrangle of mars points out evidence for the existence of an ice covered lake in gusev crater a first lake was formed by the drainage of the aquifer in the region surrounding gusev before the entry of ma adim vallis in the crater the existence of a former lake in gusev is deduced from the morphology of the ma adim delta its comparison with terrestrial antarctic analogs argues for the presence of an ice covered lake in gusev at the time that the southern part of the crater s rampart was breached by ma adim first release and for a subice lacustrine construction of the valley s delta our survey shows that ma adim vallis may have entered gusev crater as late as late hesperian early amazonian as part of a second lake episode the relationship between the variation of the gusev lake water level the volume of the lake and the surface of the lake bed is established by our bathymetric model the elevation of the former lake is deduced from the elevation of the mesa like structures in the delta of ma adim vallis furthermore the correlation of the crater frequency of gusev rampart with mars stratigraphic age shows that lakes may have occupied gusev crater over a period of time covering 2 gyrs from the formation of the crater to the last episode of water release from ma adim vallis though it is most likely that the lake was episodical the recurrence of abundant water in gusev crater makes this site a high priority for missions either for martian resource exploration or for the search of life

ventifacts at the pathfinder landing site about half of the rocks at the mars pathfinder ares vallis landing site appear to be ventifacts rocks abraded by windborne particles comparable resolution images taken by the imager for mars pathfinder imp camera and the viking landers show that ventifacts are more abundant at the pathfinder site the ventifacts occur in several forms including rocks with faceted edges finger like projections elongated pits flutes grooves and possible rills the trends of elongated pits flutes grooves and rills cluster at 280 330 clockwise from north and generally dip 10 30 away from their trend direction these orientations are indicative of southeast to northwest winds and differ from the trend of wind tails at the landing site the direction of local wind streaks and predictions of the global circulation model all of which indicate northeast to southwest winds the disparity between these data sets strongly suggests that local circulation patterns have changed since the abrasion of the ventifacted rocks the greater number of ventifacts at the pathfinder site compared to either of the viking sites is most easily explained as being due to a larger supply of abrading particles composed of either sand sized grains or indurated dust aggregates and higher surface roughness which should increase the momentum of saltating grains the pathfinder ventifacts may have formed shortly after the deposition of outflow channel sediments nearly 2 gry ago when a large local supply of abrading particles should have been abundant and atmospheric conditions may have been more conducive to rock abrasion from saltating grains based on how ventifacts form on earth the several ventifact forms seen at the pathfinder site and their presence on some rocks but not on others are probably due to local airflow conditions original rock shape exposure duration rock movement and to a lesser extent rock lithology the abundance of ventifacts at the pathfinder site together with other evidence of weathering indicates that unaltered rock surfaces are rare on mars

distribution of rocks on the gusev plains and on husband hill mars 1 the population of rocks larger than 15 cm in diameter was measured at 36 locations imaged by the spirit rover over 4 km of the traverse across the gusev plains and husband hill in gusev crater on mars the rock population observed on plains surfaces is consistent with impact fragmentation of rubbly fractured volcanics and reveals little evidence for modification by secondary processes or weathering interpretation of counts from husband hill suggest an influence by bedrock for rocks larger than 0 5 m across but the distribution of smaller rocks is consistent with ejecta possessing contributions from pre plains impact events results indicate plains surfaces experienced only tens of centimeters of eolian erosion deposition since the hesperian whereas meters rather than tens of meters of erosion modified husband hill since the early hesperian

implication of seismic attenuation for gas hydrate resource characterization mallik mackenzie delta canada wave attenuation is an important physical property of hydrate bearing sediments that is rarely taken into account in site characterization with seismic data we present a field example showing improved images of hydrate bearing sediments on seismic data after compensation of attenuation effects compressional quality factors estimated from zero offset vertical seismic profiling data acquired at mallik northwest territories canada demonstrate significant wave attenuation for hydrate bearing sediments these results are in agreement with previous attenuation estimates obtained from sonic logs and crosshole data at different frequency intervals the application of an inverse q filter to compensate attenuation effects of permafrost and hydrate bearing sediments improved the resolution of surface 3d seismic data and its correlation with log data particularly for the shallowest gas hydrate interval compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone our results show that characterization of the mallik gas hydrates with seismic data not corrected for attenuation would tend to overestimate thicknesses and lateral extent of hydrate bearing strata and hence the volume of hydrates in place

latitude dependent nature and physical characteristics of transverse aeolian ridges on mars 1 narrow angle images from the mars orbiter camera moc have revealed the common occurrence of small scale 100 m wavelength bright transverse aeolian ridges tars on the surface of mars moc images were used to assess the broad distribution of tars from 90 n to 90 s between 180 e and 240 e to investigate their relationship to latitude elevation thermal inertia geologic units local slopes and surface roughness out of 5112 examined images from the primary mission 520 10 contain evidence of tars 92 of the images with tars are located between 50 latitude and very few occur in the middle to upper latitudes or polar regions of either hemisphere tars are observed at elevations from 5 km to 3 km with the highest frequency 26 between 1 and 0 km there is no systematic relationship between the distribution of tars and global thermal inertia measurements most tars occur in geologic units associated with the channel system materials 39 and the olympus mons aureole 33 at a length scale of 1 85 km pixel the average local slopes for images with and without tars are 1 92 and 1 36 respectively of the parameters investigated the latitudinal trend of tars in both hemispheres appears to be predominantly related to surface roughness with a positive linear correlation between the surface roughness of geologic units and frequency of tars r2 0 87 factors affecting the semiglobal distribution of tars are likely related to the climate and wind regimes in which they formed but do not provide definitive evidence for either saltation or reptation formation mechanisms

mars pathfinder landing site evidence for a change in wind regime from lander and orbiter data surface features related to the wind are observed in the vicinity of the mars pathfinder mpf landing site data from the lander and in data from orbit by the viking orbiter and mars global surveyor missions features seen from the surface include wind tails associated with small rocks barchanoid duneforms ripplelike patterns and ventifact flutes cut into some rocks features seen from orbit include wind tails associated with impact craters ridges inferred to be duneforms and modified crater rims interpreted to have been eroded and mantled by windblown material the orientations of these features show two prevailing directions one is inferred to represent winds from the northeast which is consistent with strongest winds predicted by a general circulation model to occur during the martian northern winter under current conditions a second wind blowing from the ese was responsible for modifying the crater rims and cutting some of the ventifacts the two wind regimes could reflect a change in climate related to mars obliquity or some other unknown factor regardless of the cause the mpf area has been subjected to a complex pattern of winds and supply of small particles and the original surface formed by sedimentary processes from tiu and ares vallis flooding events has been modified by repeated burial and exhumation

wind wave development under alternating wind jets and wakes induced by orographic effects 1 we investigate fetch limited wind wave development under alternating coastal wind jets and wakes induced by orographic effects synthetic aperture radar and scatterometer resolve wind jets and wakes with widths of 5 40 km using the wind field and a third generation wave model we simulate the nearshore wave field as a result broader directional wave spectra are seen in wakes while we can find evolution of the directional wave spectrum with offshore distance in both wind jets and wakes especially within the offshore distance of 40 km directional wave spectra have two peaks these characteristics are well reflected in the overall directional spreading field the overall directional spreading closely corresponds to the wind speed distribution and is small large in wind jet wake region the results mean that wave energies that come from neighboring wind jet regions cross in wake regions and combine with wave energy generated by local wind in wake regions

wind related features in gusev crater mars 1 gusev crater has a complex history beginning with its formation by an impact in the noachian period and subsequent evolution including erosion and deposition associated with ma adim vallis which cut through gusev crater from the south various wind related features are found on the crater floor including albedo patterns bedforms such as barchan dunes and elongated hills possibly reflecting erosion by the wind comparisons of the orientations of these features with predictions from global and atmospheric models show wind patterns as functions of season and time of day strongest global winds occur out of the southeast in the late fall and early winter and appear to be responsible for the formation of a large dark streak that drapes 100 km across the crater floor on an intermediate scale bright wind streaks correlate with nighttime winds that flow into the crater from the rim and outlying high areas these streaks are interpreted to be deposits of dust settled from the atmosphere during times of positive atmospheric static stability smaller features include various dark streaks and duneforms the orientations of which are inferred to represent local zones of high wind shear surface stress these features also tend to correlate with strong afternoon upslope winds caused by the uneven heating of the atmosphere across the crater thus the large dark streak reflects global scale wind patterns the smaller dark features and duneforms represent flow of strong winds out of the crater in the afternoon and the small bright streaks represent deposition of dust associated with nighttime flow of wind into the crater the correlation between the wind regime predicted by the models and the orientations of the aeolian features gives confidence that the models are essentially correct because gusev is a prime candidate landing site for landers including the mars exploration rovers understanding the interplay of the atmosphere and the surface including the erosion and deposition of windblown particles is important in assessments of the science potential for these missions despite the abundance of wind related features on the floor of gusev only about 1 2 of the proposed landing ellipse area is covered with organized bedforms e g dunes although mantles of sand and dust are also likely to be present on the basis of an analysis of random landing points within the ellipse traverse distances to ridges ejecta from small craters and other potential sources of rocks are within 150 m traverse distance for 95 of the touchdown points

gusev crater wind related features and processes observed by the mars exploration rover spirit 1 wind related features observed by the rover spirit in gusev crater mars include patches of soil on the surface some of which are organized into bed forms windblown grains include dust inferred to be 2 mm in diameter microscopic imager data show the sands and granules to be rounded and relatively spherical typical of grains transported long distances by the wind the interior of bed forms exposed by rover operations suggests the infiltration of dust among the grains indicating that these sands are not currently experiencing saltation orientations of 1520 features such as bed forms and ventifacts along spirit s traverse from the landing site the columbia memorial station to west spur in the columbia hills suggest primary formative winds from the north northwest which correlate with measurements of features seen in orbiter images and is consistent with afternoon winds predicted by atmospheric models a secondary wind from the southeast is also suggested which correlates with predictions for nighttime early morning winds wind abrasion is indicated by ventifacts in the form of facets and grooves cut into rocks the orientations of which also indicate prevailing winds from the north northwest orientations of many aeolian features in the west spur area however have more scatter than elsewhere along the traverse which is attributed to the influence of local topography on the patterns of wind active dust devils observed on the floor of gusev from the columbia hills demonstrate that dust is currently mobile sequential images of some dust devils show movement as rapid as 3 8 m s consistent with wind velocities predicted by atmospheric models for the afternoon when most of the dust devils were observed sands accumulated on the rover deck in the same period suggest that some sands in the columbia hills experience active saltation two toned rocks having a light band coating at their bases are considered to represent partial burial by soils and subsequent exposure while perched rocks could represent materials lowered onto other rocks by deflation of supporting soils measurements of the heights of the light bands and the perched rocks range from 1 cm to 27 cm indicating local deflation by as much as 27 cm

initial results from the mini tes experiment in gusev crater from the spirit rover the miniature thermal emission spectrometer mini tes on spirit has studied the mineralogy and thermophysical properties at gusev crater undisturbed soil spectra show evidence for minor carbonates and bound water rocks are olivinerich basalts with varying degrees of dust and other coatings dark toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy 5 to 10 of 45 pyroxene 20 ca rich pyroxene and 25 pigeonite 40 sodic to intermediate plagioclase and 15 olivine forsterite 45 5 to 10 two spectrally distinct coatings are observed on rocks a possible indicator of the interaction of water rock and airfall dust diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0 5 to 3 mm in soils

mossbauer mineralogy of rock soil and dust at gusev crater mars spirit s journey through weakly altered olivine basalt on the plains and pervasively altered basalt in the columbia hills 1 the mossbauer spectrometer on spirit measured the oxidation state of fe identified fe bearing phases and measured relative abundances of fe among those phases for surface materials on the plains and in the columbia hills of gusev crater eight fe bearing phases were identified olivine pyroxene ilmenite magnetite nanophase ferric oxide npox hematite goethite and a fe3 sulfate adirondack basaltic rocks on the plains are nearly unaltered fe3 fet px and minor npox and magnetite columbia hills basaltic rocks are nearly unaltered peace and backstay moderately altered woolypatch wishstone and keystone and pervasively altered e g clovis uchben watchtower keel and paros with fe3 fet 0 6 0 9 fe from pyroxene is greater than fe from olivine ol sometimes absent and fe2 from ol px is 40 49 and 9 24 for moderately and pervasively altered materials respectively ilmenite fe from ilm 3 6 is present in backstay wishstone keystone and related rocks along with magnetite fe from mt 10 15 remaining fe is present as npox hematite and goethite in variable proportions clovis has the highest goethite content fe from gt 40 goethite feooh is mineralogical evidence for aqueous processes because it has structural hydroxide and is formed under aqueous conditions relatively unaltered basaltic soils fe3 fet 0 3 occur throughout gusev crater 60 80 fe from ol px 10 30 from npox and 10 from mt pasorobles soil in the columbia hills has a unique occurrence of high concentrations of fe3 sulfate 65 of fe magnetite is identified as a strongly magnetic phase in martian soil and dust

athena microscopic imager investigation 1 the athena science payload on the mars exploration rovers mer includes the microscopic imager mi the mi is a fixed focus camera mounted on the end of an extendable instrument arm the instrument deployment device idd the mi was designed to acquire images at a spatial resolution of 30 microns pixel over a broad spectral range 400 700 nm the mi uses the same electronics design as the other mer cameras but has optics that yield a field of view of 31 31 mm across a 1024 1024 pixel ccd image the mi acquires images using only solar or skylight illumination of the target surface a contact sensor is used to place the mi slightly closer to the target surface than its best focus distance about 66 mm allowing concave surfaces to be imaged in good focus coarse focusing 2 mm precision is achieved by moving the idd away from a rock target after the contact sensor has been activated the mi optics are protected from the martian environment by a retractable dust cover the dust cover includes a kapton window that is tinted orange to restrict the spectral bandpass to 500 700 nm allowing color information to be obtained by taking images with the dust cover open and closed mi data will be used to place other mer instrument data in context and to aid in petrologic and geologic interpretations of rocks and soils on mars

columbia hills mars aeolian features seen from the ground and orbit 1 abundant wind related features occur along spirit s traverse into the columbia hills over the basaltic plains of gusev crater most of the windblown sands are probably derived from weathering of rocks within the crater and possibly from deposits associated with ma adim vallis windblown particles act as agents of abrasion forming ventifacts and are organized in places into various bed forms wind related features seen from orbit results from atmospheric models and considerations of topography suggest that the general wind patterns and transport pathways involve 1 winter nighttime winds that carry sediments from the mouth of ma adim vallis into the landing site area of spirit where they are mixed with locally derived sediments and 2 winter daytime winds that transport the sediments from the landing site southeast toward husband hill similar patterns occur in the summer but with weaker winds reversals of daytime flow out of gusev crater and nighttime wind flow into the crater can account for the symmetry of the bed forms and bimodal orientations of some ventifacts

physical properties of the mars exploration rover landing sites as inferred from mini tes derived thermal inertia 1 the miniature thermal emission spectrometer mini tes on board the two mars exploration rovers provides the first opportunity to observe thermal properties from the martian surface relate these properties to orbital data and perform soil conductivity experiments under martian conditions the thermal inertias of soils bedforms and rock at each landing site were derived to quantify the physical properties of these features and understand geologic processes occurring at these localities the thermal inertia for the gusev plains rock target bonneville beacon 1200 j m 2 k 1 s 1 2 is consistent with a dense basaltic rock but the rocks at the columbia hills have a lower thermal inertia 620 j m 2 k 1 s 1 2 suggesting that they have a volcaniclasic origin bedforms on the floors of craters at both landing sites have thermal inertias of 200 j m 2 k 1 s 1 2 consistent with a particle diameter of 160 m this diameter is comparable to the most easily moved grain size in the current atmosphere on mars suggesting that these bedforms may have formed under current atmospheric conditions along the meridiani plains the thermal inertia is lower than that derived from tes and thermal emission imaging system themis orbital data this discrepancy is not well understood mini tes derived thermal inertias at gusev along a 2 5 km traverse follow trends in thermal inertia measured from orbit with tes and themis however along the traverse there are variability and mixing of particle sizes that are not resolved in the orbital thermal inertia data due to meter scale processes that are not identifiable at larger scales

overview of the spirit mars exploration rover mission to gusev crater landing site to backstay rock in the columbia hills spirit landed on the floor of gusev crater and conducted initial operations on soil covered rock strewn cratered plains underlain by olivine bearing basalts plains surface rocks are covered by wind blown dust and show evidence for surface enrichment of soluble species as vein and void filling materials and coatings the surface enrichment is the result of a minor amount of transport and deposition by aqueous processes layered granular deposits were discovered in the columbia hills with outcrops that tend to dip conformably with the topography the granular rocks are interpreted to be volcanic ash and or impact ejecta deposits that have been modified by aqueous fluids during and or after emplacement soils consist of basaltic deposits that are weakly cohesive relatively poorly sorted and covered by a veneer of wind blown dust the soils have been homogenized by wind transport over at least the several kilometer length scale traversed by the rover mobilization of soluble species has occurred within at least two soil deposits examined the presence of monolayers of coarse sand on wind blown bedforms together with even spacing of granule sized surface clasts suggests that some of the soil surfaces encountered by spirit have not been modified by wind for some time on the other hand dust deposits on the surface and rover deck have changed during the course of the mission detection of dust devils monitoring of the dust opacity and lower boundary layer and coordinated experiments with orbiters provided new insights into atmosphere surface dynamics

ma adim vallis evolution geometry and models of discharge rate abstract episodes of confined flows in ma adim vallis are reconstructed by surveying the terraces in the valley three major levels and their associated tributary systems are identified and mapped this study points out the evidence of the cessation of the valley activity between the formation of levels 1 and 2 characterized by degraded and large perched valleys which floor are not adjusted to the following flow episode level a strong asymmetry in the tributary distribution points toward a groundwater supplied water origin of the valley potential source areas are demonstrated to be in volcano tectonic regions implying a hydrothermal origin of the water that may include melted permafrost calculation of hydraulic radii valley sections and models of discharge rates associated with the morphologic and geologic survey shows that ma adim vallis was an episodic channel the lifetime of which spanned between the noachian and amazonian

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

atmospheric imaging results from the mars exploration rovers spirit and opportunity a visible atmospheric optical depth of 0 9 was measured by the spirit rover at gusev crater and by the opportunity rover at meridiani planum optical depth decreased by about 0 6 to 0 7 per sol through both 90 sol primary missions the vertical distribution of atmospheric dust at gusev crater was consistent with uniform mixing with a measured scale height of 11 56 0 62 kilometers the dust s cross section weighted mean radius was 1 47 0 21 micrometers mm at gusev and 1 52 0 18 mm at meridiani comparison of visible optical depths with 9 mm optical depths shows a visible to infrared optical depth ratio of 2 0 0 2 for comparison with previous monitoring of infrared optical depths

active dust devils in gusev crater mars observations from the mars exploration rover spirit 1 a full dust devil season was observed from spirit from 10 march 2005 sol 421 first active dust devil observed to 12 december 2005 sol 691 last dust devil seen this corresponds to the period ls 173 2 to 339 5 or the southern spring and summer on mars thermal emission spectrometer data suggest a correlation between high surface temperatures and a positive thermal gradient with active dust devils in gusev and that spirit landed in the waning stages of a dust devil season as temperatures decreased 533 active dust devils were observed enabling new characterizations they ranged in diameter from 2 to 276 m with most in the range of 10 20 m in diameter and occurred from about 0930 to 1630 hours local true solar time with the maximum forming around 1300 hours and a peak occurrence in southern late spring ls 250 horizontal speeds of the dust devils ranged from 1 to 21 m s while vertical wind speeds within the dust devils ranged from 0 2 to 8 8 m s these data when combined with estimates of the dust content within the dust devils yield dust fluxes of 3 95 10 9 to 4 59 4 kg m2 s analysis of the dust devil frequency distribution over the inferred dust devil zone within gusev crater yields 50 active dust devils km2 sol suggesting a dust loading into the atmosphere of 19 kg km2 sol this value is less than one tenth the estimates by cantor et al 2001 for regional dust storms on mars

in flight calibration and performance of the mars exploration rover panoramic camera pancam instruments 1 the mars exploration rover panoramic camera mer pancam instruments have acquired more than 60 000 high resolution multispectral stereoscopic images of soil rocks and sky at the gusev crater and meridiani planum landing sites since january 2004 these images combined with other mer data sets have enabled new discoveries about the composition mineralogy and geologic geochemical evolution of both sites one key to the success of pancam in contributing to the overall success of mer has been the development of a calibration pipeline that can quickly remove instrumental artifacts and generate both absolute radiance and relative reflectance images with high accuracy and precision in order to influence tactical rover driving and in situ sampling decisions this paper describes in detail the methods assumptions and models algorithms in the calibration pipeline developed for pancam images based on new measurements and refinements performed primarily from flight data acquired on mars major calibration steps include modeling and removal of detector bias signal active and readout region dark current electronic shutter smear and pixel to pixel responsivity flatfield variations pancam images are calibrated to radiance w m2 nm sr using refined preflight derived calibration coefficients or radiance factor i f using near in time measurements of the pancam calibration target and a model of aeolian dust deposition on the target as a function of time we are able to verify that the absolute radiance calibration of most pancam images is accurate to within about 10 or less and that the filter to filter and pixel to pixel precision of the calibrated relative reflectance data both based on measurements of the pancam calibration target are typically about 3 and 1 or less respectively examples are also presented of scientific applications made possible by the high fidelity of the calibrated pancam data these include 11 color visible to near ir spectral analysis calculation of true color and chromaticity values and generation of super resolution image data products this work represents a follow on and enhancement to the pancam preflight calibration process described by bell et al 2003

assessment of mars exploration rover landing site predictions comprehensive analyses of remote sensing data during the three year effort to select the mars exploration rover landing sites at gusev crater and at meridiani planum correctly predicted the atmospheric density profile during entry and descent and the safe and trafficable surfaces explored by the two rovers the gusev crater site was correctly predicted to be a low relief surface that was less rocky than the viking landing sites but comparably dusty a dark low albedo flat plain composed of basaltic sand and haematite with very few rocks was expected and found at meridiani planum these results argue that future efforts to select safe landing sites based on existing and acquired remote sensing data will be successful in contrast geological interpretations of the sites based on remote sensing data were less certain and less successful which emphasizes the inherent ambiguities in understanding surface geology from remotely sensed data and the uncertainty in predicting exactly what materials will be available for study at a landing site

the mars regional atmospheric modeling system model description and selected simulations the mars regional atmospheric modeling system mrams is introduced and selected model results are presented and compared with landed meteorological data when possible mrams is descended from a nonhydrostatic earth mesoscale and cloud scale model that is widely used for forecasting weather and simulating atmospheric systems over complex terrain mesoscale models such as mrams are ideal tools for making use of the high resolution data sets arriving from mars global surveyor experiments simulation of the mars pathfinder mpf landing site at lsd 142 using 1 2 degree mars orbiter laser altimeter mola derived topography and thermal emission spectrometer thermal inertia is shown to be in good agreement with observed near surface temperature pressure and wind direction simulations of topographically induced thermal circulations and mountain induced gravity waves are shown to be consistent with theory and earlier studies that tie large amplitude mountain waves to strong winds capable of producing dust streaks and local dust lifting events a large eddy simulation of the convective boundary layer provides estimates of vertical profiles of heat flux momentum flux turbulent kinetic energy and vertical velocity variance the model results suggest that the martian atmosphere is roughly two to three times more turbulent than the terrestrial atmosphere during the afternoon but fluxes are roughly an order of magnitude smaller due to the lower density dust devillike circulations are also predicted in the large eddy simulation finally a simulation that examines atmosphere surface interactions near big crater is discussed predicted surface wind stress patterns are consistent with aeolian processes inferred through mars orbiter camera imagery of big crater located near the mpf landing site c 2001 academic press

exploring gusev crater with spirit review of science objectives and testable hypotheses 1 gusev crater was selected as the landing site for the mars exploration rover mer spirit mission located at the outlet of ma adim vallis and 250 km south of the volcano apollinaris patera gusev is an outstanding site to achieve the goals of the mer mission the crater could have collected sediments from a variety of sources during its 3 9 ga history including fluvial lacustrine volcanic glacial impact regional and local aeolian and global air falls it is a unique site to investigate the past history of water on mars climate and geological changes and the potential habitability of the planet which are central science objectives of the mer mission because of its complex history and potential diversity gusev will allow the testing of a large spectrum of hypotheses with the complete suite of mer instruments evidence consistent with long lived lake episodes exist in the landing ellipse area they might offer a unique opportunity to study for the first time martian aqueous sediments and minerals formed in situ in their geological context we review the geological history and diversity of the landing site the science hypotheses that can be tested during the mer mission and the relevance of gusev to the mer mission objectives and payload

soil sedimentology at gusev crater from columbia memorial station to winter haven 1 a total of 3140 individual particles were examined in 31 soils along spirit s traverse their size shape and texture were quantified and classified they represent a unique record of 3 years of sedimentologic exploration from landing to sol 1085 covering the plains unit to winter haven where spirit spent the martian winter of 2006 samples in the plains unit and columbia hills appear as reflecting contrasting textural domains one is heterogeneous with a continuum of angular to round particles of fine sand to pebble sizes that are generally dust covered and locally cemented in place the second shows the effect of a dominant and ongoing dynamic aeolian process that redistributes a uniform population of medium size sand the texture of particles observed in the samples at gusev crater results from volcanic aeolian impact and water related processes

ma adim vallis revisited through new topographic data evidence for an ancient intravalley lake abstract based on a comprehensive study of the recent topographic map usgs mc 23 se i 2119 usgs 1991 topographical map of aeolis plus geomorphic and digital elevation we have constructed a geometric model of ma adim vallis the sedimentary history of the valley was determined by the damming of the valley by two impact craters one by the southern crater over gusev rim and the second located 120 km upstream the presence of an intravalley lake system is inferred from independent sedimentary analysis and from geomorphic evidence for valley benches peripheral and parallel topographic contour intervals of the putative intravalley lake shores suggest that the lake was covered by a thick ice sheet the longitudinal profile of the valley floor shows a peculiar reverse slope located 300 km upstream from the southern gusev crater rim we conclude that this is an accumulation of sedimentary deposits adjacent to the crater rampart which defined the northern boundary of the lake when the water level reached the lowest point of the west bank which is 0 4 km below the top of the rim of gusev crater it began to floor the surrounding plateau as the intravalley lake level raised its ice cover formed a wide lateral bench later this ponded water was funneled into gusev crater through the breaching of the southern gusev rampart by an impact crater the paleolacustrine sediments transported by the lake water that channeled through the rampart debris slope mantled the floor of gusev crater the sublacustrine sediments are promising targets for future missions and of high priority in the search for past life