the lunar far uv albedo indicator of hydration and weathering 1 we present an analysis of lunar reconnaissance orbiter lro lyman alpha mapping project lamp measurements of the dayside lunar surface at far ultraviolet wavelengths we use the strong 165 nm h2o absorption edge to look for diurnal variations in hydration we find that diurnal variations in spectral slope are indeed present they are superimposed on latitudinal and spatial variations related to composition and weathering we use two different spectral regions 164 173 nm and 175 190 nm to separate out these effects highlands and mare regions have distinct reflectance spectra with mare regions being spectrally bluer than highlands regions a consequence of the greater abundance of opaque minerals in mare regions bright ray terrains and areas known to be young such as giordano bruno crater are found to be relatively spectrally flat or red in the far uv this is consistent with a lack of space weathering which tends to make the far uv spectrum bluer due to the spectral behavior of nanophase iron large scale latitudinal variations in fuv slope are distinct and are likely due to a gradient in space weathering the diurnal variation in hydration is consistent with a solar wind origin and with loss of h2o at temperatures above 320 k far uv spectroscopy is thus shown to represent a viable method for mapping aqueous alteration even on the dayside of the moon and potentially elsewhere in the solar system

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

the martian surface as imaged sampled and analyzed by the viking landers the two viking landers touched down on the surface of mars in july and september of 1976 viking lander 1 renamed the mutch memorial station mms continued to operate for 3 martian years in chryse planitia the landing site is a rolling sparsely cratered plain impact crater size frequency distributions demonstrate that only meters of vertical erosion have occurred over the lifetime of the surface the site exhibits bedrock exposures numerous rocks excavated during cratering events indurated fine grained sediment blocky material mixed with dust and lithic fragments and aeolian drifts that overlie the blocky material and which probably accumulated during global dust storms lander 2 operated for approximately 2 martian years in utopia planitia a region subjected to volcanic impact aeolian and periglacial phenomena lander 2 is located west of the 100 km diameter crater mie on or near the distal end of the continuous ejecta deposits polygonal ground suggests that desiccation or freeze thaw processes have occurred the lander 2 site exhibits numerous rocks excavated from craters and exposed by erosion set in a matrix of crusty to cloddy sediment rare aeolian drifts overlie the crusty to cloddy material lander multispectral imaging of sediment exposures at both sites is best matched with iron rich claylike weathering products called palagonites the spectral characteristics are probably governed by thin deposits of dust from global and local dust storms darkest rocks have reflectance values that match iron rich igneous rocks although most rocks are covered with indurated coatings of the palagonitelike products chemical compositions of sediments at the two landing sites are strikingly similar suggesting an aeolian origin the compositions suggest an iron rich igneous source rock and are matched by an assemblage of clays and salts samples of blocky materials were found to have about 50 more cl and so3 than other samples implying cementation by salts the magnetic component in the sediment is silt sized or finer and may be maghemite or ultrafine grained hematite no indigenous organic compounds were found the materials were found to be highly reactive releasing o2 when h2o was added oxidizing organic nutrients on board the landers and fixing atmospheric co2 clay to silt sized particles were inferred for drift and crusty to cloddy materials no terrestrial samples have been found that replicate all the attributes of the viking samples approximately 10 m of h2o ice accumulated during both winters at lander 2 and each time evaporated over approximately 200 martian days thin layers of bright red dust from global and local dust storms accumulated at both sites during the first 2 martian years during the third winter strong winds generally scoured the mms site leaving behind a darker aeolian lag deposit bedrock at both sites formed billions of years ago and rocks have been generated and weathered slowly over geologic time but aeolian sediments accumulate become cemented and are subsequently eroded over time spans of millions of years or less the lifetime of the sedimentary deposits at the landing sites may be governed by the 105 to 106 year variations in climate due to quasi periodic changes in obliquity eccentricity and spin axis orientation

mars aeolian sand regional variations among dark hued crater floor features different regions on mars appear to have low albedo intracrater deposits that have distinct regional thermophysical and or aeolian dune characteristics thermal inertia derived from a carefully selected set of viking infrared thermal mapper observations of the dark features obtained in 1977 1978 supports this conclusion the observed similarities and differences among dark intracrater features on mars is probably a function of the combined influences of sand availability and regional wind conditions

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

mahli at the rocknest sand shadow science and science enabling activities 1 during martian solar days 57 100 the mars science laboratory curiosity rover acquired and processed a solid sediment sample and analyzed its mineralogy and geochemistry with the chemistry and mineralogy and sample analysis at mars instruments an aeolian deposit herein referred to as the rocknest sand shadow was inferred to represent a global average soil composition and selected for study to facilitate integration of analytical results with observations from earlier missions during first time activities the mars hand lens imager mahli was used to support both science and engineering activities related to sample assessment collection and delivery here we report on mahli activities that directly supported sample analysis and provide mahli observations regarding the grain scale characteristics of the rocknest sand shadow mahli imaging confirms that the rocknest sand shadow is one of a family of bimodal aeolian accumulations on mars similar to the coarse grained ripples interrogated by the mars exploration rovers spirit and opportunity in which a surface veneer of coarse grained sediment stabilizes predominantly fine grained sediment of the deposit interior the similarity in grain size distribution of these geographically disparate deposits support the widespread occurrence of bimodal aeolian transport on mars we suggest that preservation of bimodal aeolian deposits may be characteristic of regions of active deflation where winnowing of the fine sediment fraction results in a relatively low sediment load and a preferential increase in the coarse grained fraction of the sediment load the compositional similarity of martian aeolian deposits supports the potential for global redistribution of fine grained components combined with potential local contributions

diverse lithologies and alteration events on the rim of noachian aged endeavour crater meridiani planum mars in situ compositional evidence we report the results of geological studies by the opportunity mars rover on the endeavour crater rim four major units occur in the region oldest to youngest the matijevic shoemaker grasberg and burns formations the matijevic formation consisting of fine grained clastic sediments is the only pre endeavour impact unit and might be part of the noachian etched units of meridiani planum the shoemaker formation is a heterogeneous polymict impact breccia its lowermost member incorporates material eroded from the underlying matijevic formation the shoemaker formation is a close analog to the bunte breccia of the ries crater although the average clast sizes are substantially larger in the latter the grasberg formation is a thin fine grained homogeneous sediment unconformably overlying the shoemaker formation and likely formed as an airfall deposit of unknown areal extent the burns formation sandstone overlies the grasberg but compositions of the two units are distinct there is no evidence that the grasberg formation is a fine grained subfacies of the burns formation the rocks along the endeavour crater rim were affected by at least four episodes of alteration in the noachian and early hesperian i vein formation and alteration of preimpact matijevic formation rocks ii low water rock alteration along the disconformity between the matijevic and shoemaker formations iii alteration of the shoemaker formation along fracture zones and iv differential mobilization of fe and mn and caso 4 vein formation in the grasberg and shoemaker formations episodes ii and iii possibly occurred together but i and iv are distinct from either of these

the imager for mars pathfinder experiment the imager for mars pathfinder imp a stereoscopic multispectral camera is described in terms of its capabilities for studying the martian environment the camera s two eyes separated by 15 0 cm provide the camera with range finding ability each eye illuminates half of a single ccd detector with a field of view of 14 4 14 0 and has 12 selectable filters the 18 optics have a large depth of field and no focussing mechanism is required a mechanical shutter is avoided by using the frame transfer capability of the 512 512 ccd the resolving power of the camera 0 98 mrad pixel is approximately the same as the viking lander cameras however the signal to noise ratio for imp greatly exceeds viking approaching 350 this feature along with the stable calibration of the filters between 440 and 1000 nm distinguishes imp from viking specially designed targets are positioned on the lander they provide information on the magnetic properties of wind blown dust measure the wind vectors and provide radiometric standard reflectors for calibration also eight low transmission filters are included for imaging the sun directly at multiple wavelengths giving imp the ability to measure dust opacity and potentially the water vapor content several experiments beyond the requisite color panorama are described in detail contour mapping of the local terrain multispectral imaging of the surrounding rock and soil to study local mineralogy viewing of three wind socks measuring atmospheric opacity and water vapor content and estimating the magnetic properties of wind blown dust this paper is intended to serve as a guide to understanding the scientific integrity of the imp data that will be returned from mars starting on july 4 1997

soil like deposits observed by sojourner the pathfinder rover most of the soil like materials at the pathfinder landing site behave like moderately dense soils on earth with friction angles near 34 39 and are called cloddy deposits cloddy deposits appear to be poorly sorted with dust sized to granule sized mineral or rock grains they may contain pebbles small rock fragments and clods thin deposits of porous compressible drifts with friction angles near 26 28 are also present drifts are fine grained cohesions of both types of deposits are small there may be indurated soil like deposits and or coated or crusted rocks cloddy deposits may be fluvial sediments of the ares tiu floods but other origins such as ejecta from nearby impact craters should be considered drifts are probably dusts that settled from the martian atmosphere remote sensing signatures of the deposits inferred from rover observations are consistent with those observed from orbit and earth

results from the mars pathfinder camera images of the martian surface returned by the imager for mars pathfinder imp show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial aeolian and impact processes analysis of the spectral signatures in the scene at 440 to 1000 nanometer wavelength reveal three types of rock and four classes of soil upward looking imp images of the predawn sky show thin bluish clouds that probably represent water ice forming on local atmospheric haze opacity 0 5 haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers

overview of the mars pathfinder mission launch through landing surface operations data sets and science results mars pathfinder successfully landed at ares vallis on july 4 1997 deployed and navigated a small rover about 100 m clockwise around the lander and collected data from three science instruments and ten technology experiments the mission operated for three months and returned 2 3 gbits of data including over 16 500 lander and 550 rover images 16 chemical analyses of rocks and soil and 8 5 million individual temperature pressure and wind measurements path finder is the best known location on mars having been clearly identified with respect to other features on the surface by correlating five prominent horizon features and two small craters in lander images with those in high resolution orbiter images and in inertial space from two way ranging and doppler tracking tracking of the lander has fixed the spin pole of mars determined the precession rate since viking 20 years ago and indicates a polar moment of inertia which constrains a central metallic core to be between 1300 and 2000 km in radius dark rocks appear to be high in silica and geochemically similar to anorogenic andesites lighter rocks are richer in sulfur and lower in silica consistent with being coated with various amounts of dust rover and lander images show rocks with a variety of morphologies fabrics and textures suggesting a variety of rock types are present rounded pebbles and cobbles on the surface as well as rounded bumps and pits on some rocks indicate these rocks may be conglomerates although other explanations are also possible which almost definitely require liquid water to form and a warmer and wetter past air borne dust is composed of composite silicate particles with a small fraction of a highly magnetic mineral interpreted to be most likely maghemite explanations suggest iron was dissolved from crustal materials during an active hydrologic cycle with maghemite freeze dried onto silicate dust grains remote sensing data at a scale of a kilometer or greater and an earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catstrophic floods which are relatively dust free the surface appears to have changed little since it formed billions of years ago with the exception that eolian activity may have deflated the surface by 3 7 cm sculpted wind tails collected sand into dunes and eroded ventifacts fluted and grooved rocks pathfinder found a dusty lower atmosphere early morning water ice clouds and morning near surface air temperatures that changed abruptly with time and height small scale vortices interpreted to be dust devils were observed repeatedly in the afternoon by the meteorology instruments and have been imaged

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

rock abrasion tool mars exploration rover mission 1 the rock abrasion tool rat is an integral part of the athena science payload serving primarily as the geologist s rock hammer the rat will expose fresh surfaces of martian rocks to other instruments on the payload the rat also brushes dust and debris from an excavated hole or unaltered rocks to accomplish these tasks autonomously the rat a sophisticated 3 axis precision controlled device was designed data products derived from rat telemetry enable the rat to also act as an important rock physical properties science instrument the returned rat grinding and penetration rate data will be inverted and compared to a rock library on the earth the design is also very compact and lightweight the rat is contained within a cylinder 128 mm long and 85 mm in diameter and has a mass of 687 g

the color of mars spectrophotometric measurements at the pathfinder landing site we calculate the color of the martian sky and surface directly using the absolute calibration of the mars pathfinder mpf lander camera which was observed to be stable during the mission the measured colors of the martian sky and surface at the pathfinder site are identical to the viking sites i e a predominantly yellowish brown color with only subtle variations these colors are distributed continuously and fall into five overlapping groups with distinct average colors and unique spatial characteristics shadowed soil soil soil rock mixtures rock and sky we report that the primary difference between the sky color and the color of the rocks is due to a difference in brightness measurements of the sky color show that the sky reddens away from the sun and toward the horizon and that the sky color varies with time of day and is reddest at local noon we present a true color picture of the martian surface and color enhancement techniques that increase image saturation maximize color discriminability while preserving hue and eliminate brightness variations while preserving the chromaticity of the scene although mars has long been called the red planet quantitative measurements of the surface color from telescopic and surface observations indicate a light to moderate yellowish brown color the pathfinder camera measurements presented here support the claim that the red planet is not red but indeed yellowish brown

mars exploration rover engineering cameras 1 nasa s mars exploration rover mer mission will place a total of 20 cameras 10 per rover onto the surface of mars in early 2004 fourteen of the 20 cameras are designated as engineering cameras and will support the operation of the vehicles on the martian surface images returned from the engineering cameras will also be of significant importance to the scientific community for investigative studies of rock and soil morphology the navigation cameras navcams two per rover are a mast mounted stereo pair each with a 45 square field of view fov and an angular resolution of 0 82 milliradians per pixel mrad pixel the hazard avoidance cameras hazcams four per rover are a body mounted front and rear facing set of stereo pairs each with a 124 square fov and an angular resolution of 2 1 mrad pixel the descent camera one per rover mounted to the lander has a 45 square fov and will return images with spatial resolutions of 4 m pixel all of the engineering cameras utilize broadband visible filters and 1024 1024 pixel detectors

a mid triassic paleomagnetic age of the kupferschiefer mineralization in poland based on a revised apparent polar wander path for europe and russia extensive mineralization occurs in southwest poland as zoned blankets of cu ag pb zn sulphides in the kupferschiefer and zechstein limestone across the base of the late permian zechstein restricted marine sequence and in the weissliegendes sandstone at the top of the early permian rotliegendes continental volcanic and siliciclastic sequence the rote faule rf zone an oxidized hematitic equivalent of the normally pyritic basal zechstein directly underlies the copper ore and is part of the metal zoning although the origin has generally been considered to be syngenetic geologic controls of the rf ore systems in poland suggest a late diagenetic origin by converting metalliferous brines migrating through the rotliegendes clastic redbeds up along basement highs oxidizing the pyritic kupferschiefer to form the rf and precipitating base and precious metals on the reduced side of this oxidation reduction front a paleomagnetic study of the ore zone in five mines in poland the rf zone in three mines and of the barren pyritic basal zechstein from outcrops and quarries in poland germany and england was undertaken to determine the absolute age of the mineralization in the barren pyritic rocks and the copper sulphide ore thermal demagnetization and vector subtraction revealed an unstable low temperature first remanence component 76 9 n 12 2 e a63 1 6 parallel to the ambient field and a second higher temperature component 82 6 n 145 9 e a63 1 9 which could be miocene 10 20 ma or less likely cretaceous 110 ma or jurassic 180 ma this second component is erased at 350 400 c and is thought to be carried by a product of weathering after alpine age uplift and erosion no primary magnetization could be isolated in the copper or pyritic zones the rf hematite however contained a very stable third reversed component 49 0 n 157 2 e a63 2 2 which was revealed typically between 500 and 620 c and is considered to represent a secondary chemical remanent magnetization acquired during the mineralizing process in order to date the isolated magnetic components carboniferous to neogene apparent polar wander apw paths for europe and russia were constructed using paleopole catalogs mean paleopoles every 10 ma from 350 to 0 ma with a63 circles of confidence were calculated as running averages using overlapping 20 and 30 ma time intervals the rf pole corresponding to the third remanence component coincides extremely well with a middle triassic age of 240 ma on the 20 ma apw path and a late triassic age of 230 ma on the 30 ma apw path statistical analysis yields upper and lower age limits of 250 and 220 ma this triassic paleomagnetic age supports the proposed late diagenetic origin of the kupferschiefer ore deposits and suggests that the rf ore systems were formed immediately after triassic continental rifting associated with the opening of the tethys ocean to the south a likely source of the thermal anomaly necessary to initiate adequate convective velocities within the rotliegendes clastic basins

geology and mer target site characteristics along the southern rim of isidis planitia mars 1 the southern rim of the isidis basin contains one of the highest densities of valley networks several restricted paleolake basins and the stratigraphically lowest oldest terrain on mars geologic mapping in viking mgs moc and mola data odyssey themis data and other multispectral data products supports the presence of extensive fans of debris and sediments deposited along the inner rim of the isidis basin where large valleys enter the lowlands additional processes subsequent to the period of intense fluvial activity including mass flow analogous to some glacial processes have contributed to the materials accumulated on the margins of the isidis basin these have occurred along preexisting channels and valleys at the termini of major channels where they enter the plains along the highland lowland boundary if the abundant valley networks in highland terrains are the result of runoff accompanied by saturated groundwater flow as has been suggested in previous studies of ancient fluvial highland terrains then the extreme age and abundance of early valley networks in the libya montes highland rocks should have resulted in deposition of materials that record evidence for the long term presence of water in the form of aqueous alteration of polycrystalline constituents the material deposited along the basin margin is likely to consist of ancient altered highland rocks in several physical states weathered rounded and angular exposing both weathered and altered surfaces and exposures of alteration profiles in fractured faces and unweathered material from rock interiors debris fans shed off the southern rim of isidis planitia should contain materials that have experienced possible saturated groundwater flow residence within paleolake basins and derivative materials deposited during the most fluvially intensive part of martian geologic history many of these materials have also been reworked by ice related processes in situ measurements of the ancient crustal materials in the form of rocks within the debris fans and the weathered condition of the rocky material are potential sources for mineralogical evidence of climatic conditions in earliest martian geologic history the absence of alteration within rocks would on the other hand support the hypothesis that fluvial runoff during the earliest history of mars was geologically brief rather than long term and that long term saturated groundwater flow was not present determination of the presence or absence of alteration would have corresponding implications for hypotheses requiring the long term presence of aqueous solutions i e complex organic compounds and life a proposed mer site along the margin addresses realistic field science objectives of the mars exploration rover mission and the current goals of the mars exploration program in situ measurements may be important in deriving estimates of the longevity and intensity of past wetter climates

mars exploration rover athena panoramic camera pancam investigation 1 the panoramic camera pancam investigation is part of the athena science payload launched to mars in 2003 on nasa s twin mars exploration rover mer missions the scientific goals of the pancam investigation are to assess the high resolution morphology topography and geologic context of each mer landing site to obtain color images to constrain the mineralogic photometric and physical properties of surface materials and to determine dust and aerosol opacity and physical properties from direct imaging of the sun and sky pancam also provides mission support measurements for the rovers including sun finding for rover navigation hazard identification and digital terrain modeling to help guide long term rover traverse decisions high resolution imaging to help guide the selection of in situ sampling targets and acquisition of education and public outreach products the pancam optical mechanical and electronics design were optimized to achieve these science and mission support goals pancam is a multispectral stereoscopic panoramic imaging system consisting of two digital cameras mounted on a mast 1 5 m above the martian surface the mast allows pancam to image the full 360 in azimuth and 90 in elevation each pancam camera utilizes a 1024 1024 active imaging area frame transfer ccd detector array the pancam optics have an effective focal length of 43 mm and a focal ratio of f 20 yielding an instantaneous field of view of 0 27 mrad pixel and a field of view of 16 16 each rover s two pancam eyes are separated by 30 cm and have a 1 toe in to provide adequate stereo parallax each eye also includes a small eight position filter wheel to allow surface mineralogic studies multispectral sky imaging and direct sun imaging in the 400 1100 nm wavelength region pancam was designed and calibrated to operate within specifications on mars at temperatures from 55 to 5 c an onboard calibration target and fiducial marks provide the capability to validate the radiometric and geometric calibration on mars

the particle size of martian aeolian dunes the effective particle size of unconsolidated materials on the martian surface can be determined from thermal inertia due to a pore size dependence of thermal conductivity at martian atmospheric pressures because dunes consist of a narrow range of well sorted unconsolidated particles they provide for a test of the relationship between particle size and thermal inertia calculated from midinfrared emission data for the martian surface we use two independent approaches first thermal inertia data indicate that martian dunes have an average particle size of about 500 100 m or medium to coarse sand second we determine expected dune particle sizes from grain trajectory calculations and the particle size transition from suspension to saltation on earth the transition occurs for a grain when the ratio of the terminal fall velocity to the wind friction speed u t is near unity for grains at u t this occurs at about 52 m terrestrial dune sands have a mean of 250 m and are composed entirely of grains 52 m the corresponding martian transition grain size is about 210 m suggesting that martian dunes should be significantly coarser than terrestrial dunes grain saltation path length as a function of particle size also shows that under martian conditions larger grains than on earth will become suspended both approaches indicate that martian dune sand should be coarser than terrestrial dune sand thus while terrestrial dune grains are in the fine to medium sand range the average martian dune sediments are probably medium to coarse sands these results closely match the grain sizes determined from thermal inertia models providing the first direct test of the validity of these models for actual martian surface materials

bright dunes on mars seasonal changes observed on the surface of mars can in part be attributed to the transport of geological materials by wind1 images obtained by orbiting spacecraft in the 1970s showed large wind formed features such as dunes and revealed regional time varying albedos that could be attributed to the effects of dust erosion and deposition but the resolution of these images was insufficient to identify different types and sources of aeolian materials nor could they reveal aeolian deposits other than large dunes or extensive surface coverings that were redistributed by dust storms here we present images of mars with up to 50 times better resolution these images show that martian dunes include at least two distinct components the brighter of which we interpret to be composed of relatively soft minerals possibly sulphates we also find large areas of the martian surface that have several metres or more of aeolian mantle lacking obvious bedforms

athena mimos ii mossbauer spectrometer investigation 1 mossbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of fe bearing materials the miniature mossbauer spectrometer mimos ii is a component of the athena science payload launched to mars in 2003 on both mars exploration rover missions the instrument has two major components 1 a rover based electronics board that contains power supplies a dedicated central processing unit memory and associated support electronics and 2 a sensor head that is mounted at the end of the instrument deployment device idd for placement of the instrument in physical contact with soil and rock the velocity transducer operates at a nominal frequency of 25 hz and is equipped with two 57co rh mossbauer sources the reference source 5 mci landed intensity reference target fe2o3 plus fe0 and pin diode detector are configured in transmission geometry and are internal to the instrument and used for its calibration the analysis mossbauer source 150 mci landed intensity irradiates martian surface materials with a beam diameter of 1 4 cm the backscatter radiation is measured by four pin diode detectors physical contact with surface materials is sensed with a switch activated contact plate the contact plate and reference target are instrumented with temperature sensors assuming 18 fe for martian surface materials experiment time is 6 12 hours during the night for quality spectra i e good counting statistics 1 2 hours is sufficient to identify and quantify the most abundant fe bearing phases data stored internal to the instrument for selectable return to earth include mossbauer and pulse height analysis spectra 512 and 256 channels respectively for each of the five detectors in up to 13 temperature intervals 65 mossbauer spectra engineering data for the velocity transducer and temperature measurements the total data volume is 150 kb the mass and power consumption are 500 g 400 g for the sensor head and 2 w respectively the scientific measurement objectives of the mossbauer investigation are to obtain for rock soil and dust 1 the mineralogical identification of iron bearing phases e g oxides silicates sulfides sulfates and carbonates 2 the quantitative measurement of the distribution of iron among these iron bearing phases e g the relative proportions of iron in olivine pyroxenes ilmenite and magnetite in a basalt 3 the quantitative measurement of the distribution of iron among its oxidation states e g fe2 fe3 and fe6 and 4 the characterization of the size distribution of magnetic particles special geologic targets of the mossbauer investigation are dust collected by the athena magnets and interior rock and soil surfaces exposed by the athena rock abrasion tool and by trenching with rover wheels