spectral mixture modeling a new analysis of rock and soil types at the viking lander 1 site a viking lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust gray andesitelike rock and a coarse rocklike soil the rocks are covered to varying degrees by dust but otherwise appear unweathered rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander this soil probably is derived from the rocks by wind abrasion and or spallation dust is the major component of the soil and covers most of the surface the dust is unrelated spectrally to the rock but is equivalent to the global scale dust observed telescopically a new method was developed to model a multispectral image as mixtures of end member spectra and to compare image spectra directly with laboratory reference spectra the method for the first time uses shade and secondary illumination effects as spectral end members thus the effects of topography and illumination on all scales can be isolated or removed the image was calibrated absolutely from the laboratory spectra in close agreement with direct calibrations the method has broad applications to interpreting multispectral images including satellite images

fluid lava flows in gusev crater mars 1 rocks on the floor of gusev crater are basaltic in composition as determined from measurements by the mars exploration rover spirit on the basis of compositional data models of the basaltic lavas at the time of their emplacement suggest viscosities of 2 3 to 50 pa s dependent on the number of phenocrysts and vesicles that were present which would be more fluid than terrestrial tholeiitic lavas and comparable to mare lavas on the moon or archean high mg basalts on earth morphological data and crater counts derived from the high resolution stereo camera on mars express and other orbiters suggest that the lavas flooded gusev crater at about 3 65 b y and postdate older floor materials such as putative sediments emplaced by ma adim vallis

mars express high resolution stereo camera spectrophotometric data characteristics and science analysis 1 the high resolution stereo camera hrsc on the mars express mex spacecraft in orbit about mars is delivering images of the mars surface and atmosphere from its high inclination elliptical orbit that are intended to cover most of the mars surface by the end of the mission these are acquired in four specific spectral passbands that sample the scene at different parts of the extended visual spectrum from near 0 4 m to about 1 m and in five additional channels four used for stereo and one nadir that use the same fifth spectral passband these channels view from different angles and can be used for photometric and spectral analysis the data allow a variety of studies of the surface and atmosphere of mars but these require detailed understanding of the data characteristics as there are several effects including of the observation geometry and the atmosphere that need to be treated this article is a report to the science community on the current understanding of the hrsc color data after an initial analysis and also a demonstration of their capabilities for study of mars which from this study appear to be considerable we first discuss the characteristics and calibration of the hrsc spectral data the atmospheric influence on the photometric appearance of the surface materials is explored and methods of compensating are considered reflectances are calculated for surface units by assuming the dark material is basalt and scaling the entire hrsc scene using a laboratory basalt spectrum for the selected dark material area the results and the correction factors for different orbits are compared we present several examples of what could become a large volume of future science results utilizing the hrsc spectrophotometric data in conjunction with photo interpretation for example we find relatively few but very important distinct spectral components at the hrsc resolution including what we interpret as iron oxide rich material unoxidized basalt and polar ice consistent with past works the major spectral components are distributed in ways that suggest compositional mixing and the need to revise the current geologic understanding of major regions

optical scattering properties of terrestrial varnished basalts compared with rocks and soils at the viking lander sites basalt flows at the pisgah volcanic field california are mantled by aeolian silt sized deposits the bright mantle is overlain by a dense pavement of basalt cobbles smoothed by aeolian abrasion and coated with glossy dark gray and red desert varnishes in contrast the two viking landing sites on mars lack desert pavements and rocks have glossy surfaces that in some cases are brighter than soils to pursue further the scattering characteristics of varnished basalt cobbles for comparison to mars rocks laboratory measurements of bidirectional reflectance 0 69 m center wavelength were made as a function of incidence and emission angle along the principal plane for varnished and fresh basalt surfaces the reflectance data fit with a scattering model that includes specular reflections from rough surfaces and volume penetration and reflection show that the red varnished surfaces have higher single scattering albedoes and higher surface roughness values than the dark gray varnished surfaces 0 56 and 0 42 21 and 17 respectively fresh cut surfaces have lowest values 0 40 and 6 results are consistent with observations made from thin sections for these surfaces and with field observations that show dark gray varnished surfaces are smoothed by exposure to wind abrasion dark red varnished surfaces tend to be rougher because they are embedded in the aeolian mantle and develop in a protected environment application of the model to atmospherically corrected radiometrically calibrated viking lander images 0 60 to 0 74 m shows that many rocks are smoother and have single scattering albedoes higher than soils 9 versus 27 0 71 versus 0 63 respectively results are consistent with a model in which rocks at the surface of mars become smoothed by aeolian abrasion and coated with atmospheric dust lack of desert pavement on mars is probably associated with a scarcity of cobbles and a lack of soil forming processes similar bright smooth coatings are expected at other locations on mars including the pathfinder ares vallis site

submillimeter scale topography of the lunar regolith we have applied computer stereophotogrammetry to apollo lunar surface closeup camera alscc pictures of the lunar surface to construct the first ever digital topographic relief maps of undisturbed lunar soil over spatial scales from 85 m to 8 5 cm using elevation histograms fractal analysis and hapke s photometric roughness model we show that apollo 14 fra mauro imbrium ejecta is rougher than average apollo 11 mare tranquilitatis and apollo 12 oceanus procellarum mare surfaces at submillimeter to decimeter size scales we confirm the early result of k lumme et al 1985 earth moon planets33 19 29 that the cumulative distribution of elevations for lunar soil is typically well described by gaussian statistics however cumulative distributions are insensitive to asymmetries in the shapes of elevation histograms of 11 discrete elevation histograms we measured about half exhibit significant deviations from gaussian behavior we also confirm lumme et al s finding that the roughnesses of all lunar surfaces increase with decreasing size scale we further show that the scale dependence of roughness is well represented by fractal statistics the rates of change of roughness with size scale represented by fractal dimension d are remarkably similar among terrians after correcting for the contribution of large scale roughness our average value of d 2 31 0 06 falls within the range 2 0 d 2 4 reported from lunar radar studies the amplitude of roughness which we characterize with the rms slope angle at 1 mm scale varies significantly among terrains for lunar mare the average rms slope angle is 16 4 3 and that for fra mauro regolith is 25 1 by comparison to radar data we suggest that the roughness of fra mauro imbrium ejecta regolith is similar to that of lunar highland terrains we find that the gaussian slope distribution assumed in b w hapke s model 1984 icarus59 41 59 adequately describes typical lunar regolith surfaces a revised form of hapke s equation that models realistic particle phase functions and the coherent backscatter opposition effect was fitted to disk resolved lunar photometric observations and yields estimates of 27 1 for highland and 24 1 for mare regolith these values of as well as the implied relative highland mare photometric roughness ratio are best matched in our elevation data by the cummulative contributions of surface topography covering all scales greater than 0 1 mm less than 5 of the photometrically detected roughness of lunar regolith is contributed by surface relief at scales larger than 8 cm this conclusion implies that values of derived from whole disk and disk resolved photometry respectively may be taken to represent the same physical quantity in addition particulate samples used in goniophotometric measurements should not be assumed to be photometrically smooth i e 0 as is often done in laboratory applications of hapke s photometric model the predicted photometric roughness at size scales of 0 1 mm and less significantly exceed photometric estimates and suggests that there exists a measurable size scale below which topographic relief either is not photometrically detectable or is not represented in the hapke model as macroscopic roughness

near infrared imaging of mars from hst surface reflectance photometric properties and implications for mola data abstract we report initial results from hubble space telescope hst images of mars obtained at a near ir wavelength of 1042 nm between february 1995 and june 1997 the images provide the highest spatial resolution global near ir measurements of mars obtained to date the data have been calibrated to radiance factor i f to an absolute accuracy of 2 to 5 including new refinements to several hst calibration parameters and now exist as a set of coregistered map projected images spanning a range of phase angles between 10 and 41 the relatively high spatial resolution 20 30 km pixel global maps when compared with viking era global albedo maps reveal that substantial variations in mars surface albedo patterns have occurred in the past 20 years the most obvious changes include several classical dark regions that have become substantially brighter and a few formerly bright regions that have darkened the normal albedo of typical surface regions in the near ir is derived from the multiple phase angle observations and is found to be bimodal with typical bright and dark values of 0 36 and 0 18 respectively the surface near ir phase coefficient ranges from 0 0 to 0 013 mag deg and there is no systematic correlation between phase coefficient and normal albedo this observation is consistent with the diffusely scattering nature of the martian atmosphere even during times of low dust opacity the data presented here may facilitate the planning and optimization of measurements to be obtained by the mars global surveyor mgs mars orbiter laser altimeter mola which will begin mapping the planet in 1999 these hst data also provide a basis for comparison with future mola and mars orbiter camera moc data in searches for seasonal and interannual variations in surface and polar cap albedo

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

local and regional lunar regolith characteristics at reiner gamma formation optical and spectroscopic properties from clementine and earth based data a detailed remote sensing survey of the reiner gamma formation rgf region by means of earth based telescopic and clementine multispectral imaging has been made in the uv visible near infrared domain the spectral mixture analysis reveals the existence of three basic end members relevant for modeling the observed spectral variations in the rgf vicinity these are mb mare background sws southwest swirl and rgs reiner gamma soil the first two components exhibit spectral characteristics consistent with a prevailing contribution of mature mare soils for the surroundings mb and of immature mare crater like soils rgs at rgf the third intermediate albedo component sws has general characteristics of a mature mare soil but with a redder continuum slope the reported observation can be modeled by a mechanism which would remove the finest fraction in the soil particle diameter 45 m at rgf and redistribute it in the vicinity with a laterally variable proportion and local accumulations such as at sws site according to the available set of in situ data documenting variations in the chemical composition in the distribution of particle sizes and in the degree of maturity with depth in the mare regolith the characteristics depicted at rgf are those of a subsurface soil layer from a depth of the order of 0 3 0 8 m in our view the simplest way to account for the whole body of information available from the present work lies in the proposition that in the area of rgf the uppermost layer of the regolith has been optically and mechanically modified by a process involving the fall of fragments of a low density cometary nucleus previously disrupted by tidal interaction in the earth moon system we recognize however that in the present state of knowledge one cannot rule out the hypothesized existence of a zone of seismically modified terrain peripheral to the imbrium or orientale basins just beneath the mare surface that would be the actual source of the rgf magnetic anomaly

mapping sub pixel surface roughness on mars using high resolution satellite image data 1 the ratio between co registered pixels in stereo or repeat image pairs is used to constrain the deviation of the martian surface from lambertian reflection due to unresolved shadows at the pixel scale of orbiting imagers relative differences between the ratios primarily reflect differences in the effective amount of shadows seen by the sensor in the two measurements and are thus used as a relative proxy for sub pixel surface roughness sr in scene atmospheric corrections enable simple application of this two look approach which facilitates robust sr mapping at spatial resolutions comparable to the image data relative two look sr estimates can be translated to physical sr parameters through empirical calibration using ground based measurements sr variation maps in gusev crater were derived from themis and hrsc images at 18 and 30 m pixel respectively the latter were calibrated using measurements from spirit to produce a quantitative clast coverage map of spirit s initial traverse in gusev crater

mars aerosol studies with the mgs tes emission phase function observations optical depths particle sizes and ice cloud types versus latitude and solar longitude 1 emission phase function epf observations taken in 1999 2001 by mars global surveyor thermal emission spectrometer mgs tes support the broadest study of martian aerosol properties to date tes solar band and infrared ir spectral epf sequences are analyzed to obtain first time seasonal latitudinal distributions of visible optical depths particle sizes and single scattering phase functions this combined angular and wavelength coverage enables identification of two distinct ice cloud types over 45 s 45 n type 1 ice clouds exhibit small particle sizes reff 1 2 m and a distinctive backscattering increase they are most prevalent in the southern hemisphere during aphelion but also appear more widely distributed in season and latitude as topographic and high altitude 20 km ice hazes type 2 ice clouds exhibit larger particle sizes reff 3 4 m a distinct side scattering minimum at 90 100 phase angles characteristic of a change in particle shape relative to the type 1 and appear most prominently in the northern subtropical aphelion cloud belt the majority of retrieved dust visible to ir optical depth ratios are indicative of reff 1 5 0 1 m consistent with pathfinder and viking mariner 9 reanalyses however increased ratios 2 7 versus 1 7 appear frequently in the northern hemisphere over ls 50 200 indicating substantially smaller dust particles sizes reff 1 0 0 2 m at this time in addition larger reff 1 8 2 5 m dust particles were observed locally in the southern hemisphere during the peak of the 2001 global dust storm detailed spectral modeling of the tes visible band pass indicates agreement of epf derived dust single scattering albedos 0 92 0 94 with the spectrally resolved results from pathfinder observations

gusev photometric variability as seen from orbit by hrsc mars express minnaert and two term phase function hapke models are used to describe the photometric properties of the martian surface using hrsc high resolution stereo camera multi angular observations acquired along the ongoing mars express mission these observations can be pieced together to derive integrated phase functions over a wide range of phase angles the photometric diversity at 675 nm as seen from orbit of the martian surface properties across gusev is depicted with seven units three photometric units widespread across the flanks of apollinaris patera flank and the floor of gusev crater are identified as having high single scattering albedo with rather forward scattering properties low to intermediate macroscopic roughness and porous or not compacted powdered surface state as indicated by the opposition parameters another unit has the highest single scattering albedo the smoothest surface in terms of macroscopic roughness associated with an extremely forward scattering behavior the opposition parameters are consistent with the presence of transparent particles in the surface powder layer the distribution of this unit appears quite intermittent across the crater and does not seem to indicate any relationship with a given morphological structure it may correspond to sparse areas where the structure of the surface dust layer is the most preserved the most pronounced photometric changes are observed in three units associated with the low albedo features corresponding to dark wind streaks these units have a low single scattering albedo are the most backscattering surfaces across gusev have a high surface roughness and present variable surface states as shown by the opposition parameters estimates consistent with the occurrence of large grains organized in more or less packed layers clear differences are seen among these units in terms of opposition effect while one exhibits typical characteristics for the opposition effect another appears more unusual in terms of lobe width and the third suggests the occurrence of a packed compressed narrow size distribution powder surface the opposition effect thus appears to play a significant role suggesting that the surface state optical properties across gusev are strongly influenced by the porosity and packing characteristics or grain size distribution of the upper layer of the martian soil the mapping aspect of the investigation is quite useful to get a better sense of the meaning of the observed photometric variations indeed the hapke modeling suggests that surface organization surface roughness packing state is more important than the simple physical characterization of the intrinsic optical properties of the constitutive particles given the overall spatial patterns derived from the photometric analysis the variations at least for the western and central part of gusev crater are likely partly driven by the prevailing wind regimes considered to be oriented north northwest south southeast and disturbing the very upper surface layer the present photometric results agree with independent investigations based on thermal inertia reflectance spectroscopy in situ photometric and microscopic imaging and support the idea of a thin layer of fine grained dust being stripped off in the low albedo units to reveal a dark basaltic substrate comprising coarse grained materials

coordinated analyses of orbital and spirit rover data to characterize surface materials on the cratered plains of gusev crater mars 1 comparison of the mars exploration rover spirit s pancam 0 4 to 1 0 m and mars express observatoire pour la mineralogie l eau les glaces et l activite omega 0 4 to 2 5 m spectral reflectance data over spirit s traverses shows that gusev cratered plains are dominated by nanophase ferric oxide rich dust covering weakly altered basaltic sands this interpretation is also consistent with both observations from omega data covering plains beyond the traverse region and interpretations of data from the other payload instruments on the spirit rover omega observations of relatively low albedo regions where dust has presumably been stripped by dust devils show negative spectral reflectance slopes from 1 5 to 2 5 m and moderately masked spectral features which are indicative of olivine or pyroxene high albedo regions north and south of the spirit landing site have flat spectral reflectance slopes and few spectral features although all spectra have a nanophase ferric oxide absorption edge between 0 4 and 0 75 m comparison of themis derived thermal inertia values with omega derived spectral parameters shows that although the dust cover can be optically thick 0 4 to 2 5 m wavelength region in some areas it is not thick enough 1 cm to mask the thermal inertia of the underlying substrate for areas included in this study

long term shore platform surface lowering rates revisiting gill and lang after 32 years abstract in 1978 e d gill and j g lang installed 53 micro erosion meter mem sites on shore platforms along the otway coast in south eastern australia surface lowering rates were originally determined from 2 yr of measurements 1979 and 1980 and showed that the mean annual rate of lowering from all sites was 0 37 mm yr 1 we re measured these mem sites 32 yr after the first set of readings were taken in february 1979 we relocated 49 of the original 53 bolt sites and were able to measure 45 of them from the sites we measured the mean annual rate of shore platform lowering was 0 31 mm yr 1 rates of surface lowering on shore platforms are commonly reported from studies of only two or three years and only one other record exceeds 30 yr kaikoura peninsula nz 1 09 mm yr 1 in that case fewer than half of the original bolt sites were functioning because erosion had removed bolts along the otway coast rates of erosion are much slower hence the greater number of still readable sites after 32 yr compared to other micro erosion meter studies the rates reported here are at the lower end of the range of values from around the world but nevertheless consistent with rates from the otway coast and others in similar lithology we found no statistical difference between erosion rates calculated over 2 yr 1979 to 1980 and 32 1979 to 2011 years supporting the view that shore platform lowering rates measured over 2 yr are representative of decadal scales

preliminary results on photometric properties of materials at the sagan memorial station mars reflectance measurements of selected rocks and soils over a wide range of illumination geometries obtained by the imager for mars pathfinder imp camera provide constraints on interpretations of the physical and mineralogical nature of geologic materials at the landing site the data sets consist of 1 three small photometric spot subframed scenes covering phase angles from 20 to 150 2 two image strips composed of three subframed images each located along the antisunrise and antisunset lines photometric equator covering phase angles from 0 to 155 and 3 full image scenes of the rock yogi covering phase angles from 48 to 100 phase functions extracted from calibrated data exhibit a dominantly backscattering photometric function consistent with the results from the viking lander cameras however forward scattering behavior does appear at phase angles 140 particularly for the darker gray rock surfaces preliminary efforts using a hapke scattering model are useful in comparing surface properties of different rock and soil types but are not well constrained possibly due to the incomplete phase angle availability uncertainties related to the photometric function of the calibration targets and or the competing effects of diffuse and direct lighting preliminary interpretations of the derived hapke parameters suggest that 1 red rocks can be modeled as a mixture of gray rocks with a coating of bright and dark soil or dust and 2 gray rocks have macroscopically smoother surfaces composed of microscopically homogeneous clear materials with little internal scattering which may imply a glass like or varnished surface

the geology of heidrun a giant oil and gas field on the mid norwegian shelf the heidrum field is located in the haltenbanken region on the mid norwegian continental shelf 165 mi from shore in water depths of approximately 1 150 ft the field is a giant cimmerian structure with hydrocarbons trapped in jurassic sandstone reservoirs the field has 750 mm bbl recoverable oil reserves with associated gas reserves of 0 45 tcf and free gas reserves of 1 3 tcf the accumulation extends over 14 4 mi and was unitized in 1989 with 75 of the field in block 6507 7 and 25 of the field in block 6507 8 the 6507 7 block was acquired by conoco norway and partners in 1984 in the eighth round of licenses offered by the norwegian government the acquisition was based on extensive in house exploration regional studies which identified a jurassic rift element in haltenbanken and the potential for the generation of liquid hydrocarbons the heidrun structure is a large southwesterly plunging horst block on the southwestern flank of the nordland ridge and was formed during the cimmerian extensional tectonic phase in the late jurassic early cretaceous the heidrun reservoirs are severely truncated at the northern edge of the structure and are sealed by cretaceous shales the heidrun jurassic reservoir rock the fangst group and themore tilje and are formations were deposited on the southeastern flank of the developing northeastern atlantic rift domain the shallow burial depth 8 100 ft has limited compaction effects and reservoir quality therefore is enhanced with permeabilities up to 10 d and porosities in excess of 30 in the cleaner sands of the fangst the primary sources for the petroleum is the upper jurassic spekk formation which is mature in the downdip areas 3 10 mi southwest and west of heidrun therefore fairly long petroleum migration paths are inferred a 5 000 km high resolution three dimensional seismic survey was acquired in 1986 the three dimensional data set forms the basis for detailed geologic and reservoir models less

integration of the clementine uv vis spectral reflectance data and the lunar prospector gamma ray spectrometer data a global scale multielement analysis of the lunar surface using iron titanium and thorium abundances 1 we present a statistical analysis based on a systematic clustering method of a data set integrating the global abundances maps of iron titanium and thorium derived from clementine and lunar prospector homogeneous geological units are compositionally characterized and spatially defined in relation to the major rock types sampled on the moon with the lowest abundances in fe ti and th found on the moon the lunar highlands terrains are quite homogeneous with two major large feldspathic units one being slightly more mafic than the other two distinct regions with unique compositions are unambiguously identified the procellarum kreep terrane pkt and the south pole aitken spa the pkt which includes all the units with th abundances higher than 3 5 ppm kreep rich materials is delimited by an almost continuous ring like unit in particular it includes the western nearside maria except for mare humorum within the pkt a th rich unit corresponding to the highest th concentrations found on the moon may represent kreep volcanic deposits excavated from relatively shallow depth with concentrations in fe ti and th enhanced relative to the surrounding highlands the south pole aitken basin floor represents a large mafic anomaly on the farside suggesting wide deposits of lower crust and possible mantle materials however due to indirect residual latitude effects in the clementine spectral reflectance measurements iron abundances might have been overestimated in spa thus implying that crustal materials rather than mantle materials might represent the dominant contributor to the mafic component exposed on the basin floor

thermophysical properties of the mer and beagle ii landing site regions on mars 1 we analyzed remote sensing observations of the isidis basin gusev crater and meridiani planum landing sites for beagle ii mer a spirit and mer b opportunity spacecraft respectively we emphasized the thermophysical properties using daytime and nighttime radiance measurements from the mars global surveyor mgs thermal emission spectrometer and mars odyssey thermal emission imaging system themis and thermal inertias derived from nighttime data sets themis visible images mgs mars orbiter camera moc narrow angle images and mgs mars orbiter laser altimeter mola data are incorporated as well additionally the remote sensing data were compared with ground truth at the mer sites the isidis basin surface layer has been shaped by aeolian processes and erosion by slope winds coming off of the southern highlands and funneling through notches between massifs in the gusev region surface materials of contrasting thermophysical properties have been interpreted as rocks or bedrock duricrust and dust deposits these are consistent with a complex geological history dominated by volcanic and aeolian processes at meridiani planum the many layers having different thermophysical and erosional properties suggest periodic deposition of differing sedimentological facies possibly related to clast size grain orientation and packing or mineralogy

classification of surface units in the equatorial region of mars based on viking orbiter color albedo and thermal data viking orbiter color albedo and thermal inertia data for the equatorial region of mars were utilized as a five dimensional data set to search for clusters that correspond to mappable surface units a principal components analysis shows that 84 of the variance within the data for the equatorial region 30 of equator can be carried along two vector directions these vector directions typify the dominant trend of martian surface materials the first direction indicates that as the surface materials become brighter at red wavelengths they also brighten at green and violet wavelengths the second direction implies that as the albedo increases the thermal inertia decreases these dominant trends were deemphasized by stretching the data from a five dimensional elliptical swarm into a hypersphere through the use of principal component techniques the decorrelated data were then plotted in a triangle diagram with red violet albedo and thermal inertia apices to facilitate discrimination of inherent clusters unit maps for the region within 15 latitude of the equator and bounded by 0 to 50 and 280 to 360 w longitude were generated on the basis of the clusters up to eight clusters can be identified and mixing between clusters appears to be important the three major clusters consist of bright red materials with low thermal inertia dark relatively gray materials with high inertia and materials with intermediate values of color albedo and thermal inertia mantling by aeolian deposits or volcanic materials is prevalent in the brightest reddest unit with the lowest thermal inertia while the darker grayer units with higher thermal inertia are dominated by marelike plains the mantling is apparent in viking orbiter images with resolutions from 8 to 30 m per pixel

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

properties of the hermean regolith iv photometric parameters of mercury and the moon contrasted with hapke modelling a comparison of the photometric properties of mercury and the moon is performed based on their integral phase curves and disk resolved image data of mercury obtained with the swedish vacuum solar telescope proper absolute calibration of integral v band

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

mars surface mineralogy from hubble space telescope imaging during 1994 1995 observations calibration and initial results visible to near infrared observations of mars were made with the hubble space telescope hst during 1994 1995 with the goals of monitoring seasonal variability of the surface and atmosphere and mapping specific spectral units to constrain the planet s surface mineralogy this paper presents the details of the collection and calibration of the data concentrating specifically on the near ir data that were obtained exclusively for the surface mineralogy aspect of our hst mars observing program we also present some initial results from the calibrated data set our calibration procedures included the standard pipeline processing steps supplemented by special procedures required for use with the linear ramp filters on the wide field planetary camera 2 instrument and an additional point spread function deconvolution procedure applied in order to realize the full potential spatial resolution of the images 23 to 64 km pixel between august 1994 and august 1995 the calibration results in a set of images projected onto a standard map grid and presented in radiance factor i f units having an estimated 5 photometric accuracy based on the performance of hst and comparisons with previous ground based and spacecraft mars spectra initial scientific analyses of these data reveal 1 distinct red blue color units within the classical bright regions similar to those seen in viking orbiter images and possibly related to variations in nanophase and or crystalline ferric mineral abundance 2 near ir spectral slope variations correlated with albedo on a large scale darker is bluer near ir slope but exhibiting wider variations among many of the small scale features visible in the data 3 an absorption at 860 nm that occurs in all regions but which is 3 to 5 stronger in many of the classical dark regions than in the bright regions possibly because of a greater abundance of a well crystalline ferric phase like hematite or a very low ca pyroxene or opx cpx mixture and 4 an absorption from pyroxene at 953 nm with a band depth that is inversely correlated with albedo bright regions 0 to 5 deep dark regions 7 to 15 deep and which shows the highest band depth values in individual craters calderas and other small geologic units that are resolved in the images

martian phase function modeling the visible to near infrared surface photometric function using hst wfpc2 data abstract images of mars in the visible to near infrared acquired from 1996 to 2005 using the hubble space telescope wfpc2 have been used to model the martian surface photometric function at 502 673 953 and 1042 nm these data range in spatial resolution from 12 to 70 km pixel at the sub earth point and in phase angle coverage from 0 34 to 40 5 the wfpc2 images have been calibrated to radiance factor or i f and projected to a cylindrical map for coregistration and comparison to similarly mapped spacecraft data sets of albedo topography thermal inertia composition and geology we modeled the observed i f as a function of phase angle using minnaert lambert lunar lambert and hapke photometric functions for numerous regions of interest binned into albedo units defined by viking and tes albedo maps and thermal inertia units defined by tes thermal inertia maps visibly opaque water ice clouds and data acquired under high dust opacity conditions were excluded from the analysis our modeling suggests that under average to low atmospheric dust opacity conditions and over this range of phase angles the photometric properties of the martian surface at 502 673 953 and 1042 nm are best modeled by lunar lambert functions with parameters derived for three surface units defined by low moderate and high tes bolometric albedos

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

pancam multispectral imaging results from the spirit rover at gusev crater panoramic camera images at gusev crater reveal a rock strewn surface interspersed with high to moderate albedo fine grained deposits occurring in part as drifts or in small circular swales or hollows optically thick coatings of fine grained ferric iron rich dust dominate most bright soil and rock surfaces spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine atmospheric observations show a steady decline in dust opacity during the mission and astronomical observations captured solar transits by the martian moons phobos and deimos as well as a view of earth from the martian surface

a volcanic interpretation of gusev crater surface materials from thermophysical spectral and morphological evidence 1 gusev crater the mars exploration rover spirit landing site 160 km diameter 14 5 s 184 5 w has been identified in previous studies as a prime site of geological and exobiological interest on the basis of its potential for having hosted a fluviolacustrine environment such environment may have been favorable for the development of biological activity the origin and nature of the materials present at the surface of gusev crater are still being debated in previous studies based on geomorphological and thermophysical data surface materials in the crater have been interpreted as originating from fluviolacustrine volcanic or aeolian processes or combinations thereof we present results from the analysis of newly compiled thermophysical thermal emission spectrometer tes and thermal emission imaging system themis spectroscopic tes and visible themis and mars observer camera data for the gusev region these data were analyzed using a new mosaicking technique developed to match the values of contiguous scenes and to produce seamless mosaics apt for geological interpretation thermophysical spectroscopic and morphological evidence point to the presence of local outcrops of lava flows of basaltic composition materials consistent with a regolith developed from basaltic materials fine grained deposits of basaltic composition strongly modified by wind erosion and wind deposits according to these findings we conclude that most of the materials occupying the present surface of gusev have characteristics consistent with those of volcanic and aeolian deposits fluviolacustrine deposits proposed by other authors may exist under the volcanic materials and may be exposed in impact craters

ice rich terrain in gusev crater mars abstract the morphology of materials on the floor of gusev crater 14 s 175 w mars imply a history of volcanism and subsequent removal of an ice rich deposit fluid lava flows observed in the western portion of gusev crater paradoxically terminate in a steep thick 60 m flow front adjacent to hummocky terrain the hummocky terrain is morphologically similar to deglaciated terrain on earth generated when glacial debris are left behind after the glacier has retreated we propose the following scenario for the floor of gusev crater first ice rich material was deposited adjacent to thira crater second fluid lavas were emplaced and ponded against the ice rich deposits at some later time the ice within the deposit sublimated leaving hummocky terrain current age estimates for the gusev flows are hesperian suggesting that the ice removal occurred in the upper hesperian or more recently if this hypothesis is correct quench features glassy rinds columnar jointing should be observed at the lava flow margin the hummocky deposit should be poorly sorted angular debris

planetary regolith surface analogs optimized determination of hapke parameters using multi angular spectro imaging laboratory data this work presents a method for a determination of the global set of parameters involved in hapke s model for planetary surface analogs when dealing with a set of angular conditions representative of the usual range of observation in planetary exploration for spaceborne optical instruments the present approach is founded on a genetic algorithm the whole set of hapke parameters is treated simultaneously without any a priori assumptions it limits the risk of meeting a local extreme and the stability and repeatability of the determination are improved moreover it requires less computational time than a monte carlo routine as a demonstration using multi angular measurements acquired by a new laboratory wide field multispectral imaging facility parameter values for various grain sizes and material compositions of planetary regolith surface analogs are derived and their potential wavelength dependence is studied the results coherent with the literature validate all the steps in our methodology we focus our interest in the understanding of the physical meaning of hapke s parameters in particular of the parameter of the shadowing function for macroscopic roughness it appears that the features smaller than the centimeter scale contribute predominantly to the photometric effect related to the rocky aspect of planetary soil surfaces the parameter may thus be mainly considered as an integral of the roughness properties in the submillimetric centimetric range indeed the most representative case for describing natural regolith surface lies in texture classes in the millimeter range not involving necessarily a high macroscopic roughness with large surface slopes at hundreds of meters scale these findings strengthen the case that depends on both the grain size and the material geological properties

estimating sub pixel surface roughness using remotely sensed stereoscopic data abstract surface roughness at the scale of 10 2 10 1 m can be estimated using the ratio rr between surface reflected solar radiance measured from two view angles at nearly the same time as rr is primarily a function of the difference between effective sub pixel shading observed from the two view angles the divergence from unity rr values which are expected for smooth lambertian surfaces they have no shadows was found to be proportional to roughness at the 10 2 10 1 m scale of geomorphic desert surfaces ground based rr values at 1 m resolution as well as remotely acquired rr values at 4 15 and 50 m resolutions were compared with observed surface roughness in two hyperarid test sites located in death valley california usa and the southern negev desert in israel the aster advanced spaceborne thermal emission and reflection radiometer 15 m stereoscopic capability is identified as an effective resource for obtaining relative sub pixel surface roughness estimates that are largely independent of surface composition and relatively insensitive to atmospheric effects

surface roughness and geological mapping at subhectometer scale from the high resolution stereo camera onboard mars express the quantitative measurement of surface roughness of planetary surfaces at all scales provides insights into geological processes a characterization of roughness variations at the scale of a few tens of meters is proposed that complements the analysis of local topographic data of the martian surface at kilometer scale as achieved from the mars orbiter laser altimeter mola data and at the subcentimeter scale using photometric properties derived from multi angular observations relying on a gabor filtering process an algorithm developed in the context of image classification for the purpose of texture analysis has been adapted to handle data from the high resolution stereo camera hrsc the derivation of roughness within a wavelength range of tens of meters combined with analyses at even longer wavelengths gives an original view of the martian surface the potential of this approach is evaluated for different examples for which the geological processes are identified and the geological units are mapped and characterized in terms of roughness

spectral variability among rocks in visible and near infrared multispectral pancam data collected at gusev crater examinations using spectral mixture analysis and related techniques 1 visible and near infrared vnir multispectral observations of rocks made by the mars exploration rover spirit s panoramic camera pancam have been analyzed using a spectral mixture analysis sma methodology scenes have been examined from the gusev crater plains into the columbia hills most scenes on the plains and in the columbia hills could be modeled as three end member mixtures of a bright material rock and shade scenes of rocks disturbed by the rover s rock abrasion tool rat required additional end members in the columbia hills there were a number of scenes in which additional rock end members were required the sma methodology identified relatively dust free areas on undisturbed rock surfaces as well as spectrally unique areas on rat abraded rocks spectral parameters from these areas were examined and six spectral classes were identified these classes are named after a type rock or area and are adirondack lower west spur clovis wishstone peace and watchtower these classes are discriminable based primarily on near infrared nir spectral parameters clovis and watchtower class rocks appear more oxidized than wishstone class rocks and adirondack basalts based on their having higher 535 nm band depths comparison of the spectral parameters of these gusev crater rocks to parameters of glass dominated basaltic tuffs indicates correspondence between measurements of clovis and watchtower classes but divergence for the wishstone class rocks which appear to have a higher fraction of crystalline ferrous iron bearing phases despite a high sulfur content the rock peace has nir properties resembling plains basalts

the surface of syrtis major composition of the volcanic substrate and mixing with altered dust and soil syrtis major is an old low relief volcanic plateau near the equatorial regions of mars it is a persistent low albedo feature on the planet and is thought to contain a high abundance of exposed bedrock and or locally derived surface material and debris spatially resolved variations in surface spectral properties and therefore composition are investigated with data from the imaging spectrometer for mars ism instrument ism obtained 128 wavelength channel spectra from 0 76 to 3 16 m for contiguous pixels approximately 22 22 km in size across much of the plateau the value and spatial distribution of four primary spectral variables albedo continuum slope wavelength of the ferric ferrous band minimum area of the ferric ferrous absorption are mapped and coregistered to viking digital photomosaics analysis of these maps shows that although there is a high degree of overall spectral variability on the plateau the key indicators of mafic mineralogy are relatively homogeneous detailed examination of reflectance spectra from representative areas across the plateau indicate the volcanic surface is dominated by augite bearing basalts and the pyroxene composition in the basalts is estimated to be 0 275 0 075 ca ca fe mg and 0 3 0 1 fe fe ca mg additional mineral components may include olivine feldspar and glass most of the spectral variability on the plateau is interpreted to result from mixing of volcanic bedrock and or locally derived surface material and debris with highly altered dust and soil in western syrtis major the altered material is a transient component on the surface or occurs in large spatially coherent patches e g crater rims in eastern syrtis major it is apparent that the dust components are firmly fixed to the basaltic substrate as a stable oxide rind or coating

nature and distribution of surficial deposits in chryse planitia and vicinity mars color images of bright red dust deposits at the mutch memorial station were acquired at variable incidence angles during sol 611 subsolar longitude 70 northern spring season after removing effects due to atmospheric scattering and absorption the data were used to estimate the independent variables in the hapke 1986 photometric function in blue green and red coordinates the vector representing the space radiance factor of the landing site extracted from viking orbiter images acquired on sol 609 is separated by a euclidean distance of only 0 022 units and an angle of only 1 5 from the vector estimated from the station data for the orbiter lighting and viewing geometries this result implies that light reflected from dust exposures dominates the orbiter signal multiplicative and additive atmospheric terms cancel one another and surface roughness is a second order effect in the orbiter data dust radiance factors computed from station data are most like laboratory spectra for fine grained hawaiian palagonite and are indistinguishable from earth based spectra of classical bright areas color composites of orbiter images show that the dust is found immediately south of acidalia planitia and in association with topographic barriers such as craters and cliffs examination of viking infrared thermal mapper data shows that the dust deposits typically do not have distinctive thermal inertia signatures implying that the deposits are optically thick hundreds of micrometers but thinner than the diurnal thermal skin depth centimeters dark gray material with thermal inertia values 8 12 10 3 cal cm 2 s 1 2 k 1 indicative of sand grain sizes 0 5 1 5 mm dominates the acidalia planitia lowlands and parts of kasei vallis this material also occurs as dark streaks extending from craters in xanthe terra and oxia palus space radiance factors of dark gray material are similar to spectra of mafic rock mixed with a minor amount of palagonitelike material material that is darker than but just as red as the dust deposits occurs in lunae planum xanthe terra and oxia palus areas of intermediate elevation multiple phase angle orbiter images suggest that the dark red exposures are a mixture of bright red and dark gray materials with the dark red exposures being relatively rough at a subpixel scale as compared to exposures of the other two materials thus only two types of materials can be detected in the data covering the study area palagonitelike dust and mafic rock fragments thermal inertia values 4 8 10 3 cal cm 2 s 1 2 k 1 for the dark red material are consistent with the presence of fine to medium sand size particles 0 10 0 5 mm such material should be easily moved by winds the lack of aeolian features implies that the dark red deposits are not composed of loose material rather they are probably more eroded versions of blocky soil or duricrust cemented dust and rock fragments exposed at the station both bright red dust aeolian suspension load and dark gray materials saltation traction loads migrate over the dark red substrate the overall distribution of the surficial units is controlled by topography at a variety of length scales lower wind threshold friction velocities associated with higher atmospheric densities in lowlands keep dust from accumulating and duricrust from forming while higher threshold velocities in highlands lead to net accumulation of dust local topographic obstacles craters walls ridges perturb wind flow and lead to local accumulation or erosion at a variety of elevations in addition the bright red dust ubiquitously found between exposures of dark gray and dark red materials may accumulate as the wind velocity gradient decreases at the transition from smoother dark gray exposures to rougher dark red exposures the distribution of the materials must also be modulated by climatic variations induced by quasi periodic oscillations in obliquity eccentricity and spin axis direction constraining these surficial deposits to be 1 ma

galileo photometry of asteroid 243 ida galileo imaging observations over phase angles 19 5 to 109 8 are combined with near opposition earth based data to derive the photometric properties of ida to first order these properties are uniform over the surface and well modeled at 0 55 m by hapke parameters 0 0 22 h 0 020 b0 1 5 g 0 33 and 18 with corresponding geometric albedop 0 21 0 030 01and bond albedoab 0 081 0 0170 008 ida s photometric properties are more similar to those of average s asteroids p helfenstein and j veverka 1989 asteroids ii univ of arizona press tucson than are those of 951 gaspra two primary color units are identified on ida terrain a exhibits a spectrum with relatively shallower 1 m absorption and a relatively steeper red spectral slope than average ida while terrain b has a deeper 1 m absorption and a less steep red slope the average photometric properties of ida and terrain a are similar while those of terrain b differ mostly in having a slightly higher value of 0 0 22 versus 0 21 suggesting that terrain b consists of slightly brighter more transparent regolith particles galileo observations of ida s satellite dactyl over phase angles 19 5 to 47 6 suggest photometric characteristics similar to those of ida the major difference being dactyl s slightly lower albedo 0 20 compared to 0 21