nonlinear simulations of jupiter s 5 micron hot spots large scale nonlinear simulations of jupiter s 5 micron hot spots produce long lived coherent structures that cause subsidence in local regions explaining the low cloudiness and the dryness measured by the galileo probe inside a hot spot like observed hot spots the simulated coherent structures are equatorially confined have periodic spacing propagate west relative to the flow are generally confined to one hemisphere and have an anticyclonic gyre on their equatorward side the southern edge of the simulated hot spots develops vertical shear of up to 70 meters per second in the eastward wind which can explain the results of the galileo probe doppler wind experiment

the atmosphere of titan an analysis of the voyager 1 radio occultation measurements abstract two coherently related radio signals transmitted from voyager 1 at wavelengths of 13 cm s band and 3 6 cm x band were used to probe the equatorial atmosphere of titan the measurements were conducted during the occultation of the spacecraft by the satellite on november 12 1980 an analysis of the differential dispersive frequency measurements did not reveal any ionization layers in the upper atmosphere of titan the resolution was approximately 3 10 3 and 5 10 3 electrons cm 3 near the evening and morning terminators respectively abrupt signal changes observed at ingress and egress indicated a surface radius of 2575 0 0 5 km leading to a mean density of 1 881 0 002 g cm 3 for the satellite the nondispersive data were used to derive profiles in height of the gas refractivity and microwave absorption in titan s troposphere and stratosphere no absorption was detected the resolution was about 0 01 db km at the 13 cm wavelength the gas refractivity data which extend from the surface to about 200 km altitude were interpreted in two different ways in the first it is assumed that n 2 makes up essentially all of the atmosphere but with very small amounts of ch 4 and other hydrocarbons also present this approach yielded a temperature and pressure at the surface of 94 0 0 7 k and 1496 20 mbar respectively the tropopause which was detected near 42 km altitude had a temperature of 71 4 0 5 k and a pressure of about 130 mbar above the tropopause the temperature increased with height reaching 170 15 k near the 200 km level the maximum temperature lapse rate observed near the surface 1 38 0 10 k km corresponds to the adiabatic value expected for a dry n 2 atmosphere indicating that methane saturation did not occur in tbis region above the 3 5 km altitude level the lapse rate dropped abruptly to 0 9 0 1 k km and then decreased slowly with increasing altitude crossing zero at the tropopause for the n 2 atmospheric model the lapse rate transition at the 3 5 km level appears to mark the boundary between a convective region near the surface having the dry adiabatic lapse rate and a higher stable region in radiative equilibrium in the second interpretation of the refractivity data it is assumed instead that the 3 5 km altitude level corresponds to the bottom of a ch 4 cloud layer and that n 2 and ch 4 are perfectly mixed below this level these assumptions lead to an atmospheric model which below the clouds contains about 10 ch 4 by number density the temperature near the surface is about 95 k arguments concerning the temperature lapse rates computed from the radio measurements appear to favor models in which methane forms at most a limited haze layer high in the troposphere

zonal motion and structure in jupiter s upper troposphere from voyager infrared and imaging observations abstract voyager infrared data are used to produce global cylindrical projection digital maps of temperature at the 270 and 150 mb pressure levels infrared cloud optical depths at 45 and 5 m wavelength and the ammonia abundance near the 680 mb level voyager imaging data are used to produce maps of orange reflectivity and violet reflectivity effective wavelengths of 0 58 and 0 41 m respectively the zonal motions of the dominant structures in each of the quantities are evaluated using cross correlation of the maps structures in the maps of cloud optical depths ammonia abundance and visible reflectivities show the same zonal motion at almost all latitudes the dominant upper tropospheric thermal structures move at a rate which is far different than the cloud indicators and they remain stationary with respect to the bulk rotation of the planet comparison of these motions with the zonally averaged thermal wind shear inthe upper troposphere indicates that the thermal structures move at a rate far different than the local fluid velocity we present a simple theory which suggests that these slowly moving thermal structures could represent the influence of a disturbance seated in a slowly moving region deep in jupiter s atmospheres although this explanation is not unique intercomparison of the motions and longitudinal alignment of the various cloud indicators with the thermal wind shear in the upper troposphere shows that the few latitudes at which differences exist correlate strikingly with latitudes of largest shear suggesting that the observed differences may reflect height differences in observed cloud features fourier analysis of the maps of temperature at 270 mb show a robust stationary feature at a zonal wavenumber of 9 near 15 n latitude the maps of cloud optical depth at 45 m show a feature at zonal wavenumber 11 near 20 n these periodicities may be related to similar structures recently detected in groundbased observations and their longevity and robustness may indicate preferred wavemodes of the atmosphere

fabric analysis application to paleolithic sites abstract this paper reviews data on the strike and dip fabric of clasts in slope deposits and stresses the usefulness of such investigations in regard to the study of prehistoric living floors particularly to test the occurrence of disturbance processes nine paleolithic sites have been studied for this purpose five of them located in rockshelters or cave entrances show a preferred orientation of the artefacts along the slope this pattern appears to be the result of periglacial mass movements so far such processes have been largely underestimated and may explain the absence of clear anthropogenic structures at these sites

the martian subsurface as a potential window into the origin of life few traces of earth s geologic record are preserved from the time of life s emergence over 3 800 million years ago consequently what little we understand about abiogenesis the origin of life on earth is based primarily on laboratory experiments and theory the best geological lens for understanding early earth might actually come from mars a planet with a crust that s overall far more ancient than our own on earth surface sedimentary environments are thought to best preserve evidence of ancient life but this is mostly because our planet has been dominated by high photosynthetic biomass production at the surface for the last 2 500 million years or more by the time oxygenic photosynthesis evolved on earth mars had been a hyperarid frozen desert with a surface bombarded by high energy solar and cosmic radiation for more than a billion years and as a result photosynthetic surface life may never have occurred on mars therefore one must question whether searching for evidence of life in martian surface sediments is the best strategy this perspective explores the possibility that the abundant hydrothermal environments on mars might provide more valuable insights into life s origins ancient hydrothermal deposits formed in the martian subsurface may be the best targets for finding evidence for ancient life on mars and clues about the origin of life on earth

composition morphology and stratigraphy of noachian crust around the isidis basin definitive exposures of pristine ancient crust on mars are rare and the finding that much of the ancient noachian terrain on mars exhibits evidence of phyllosilicate alteration adds further complexity we have analyzed high resolution data from the mars reconnaissance orbiter in the well exposed noachian crust surrounding the isidis basin we focus on data from the compact reconnaissance imaging spectrometer for mars as well as imaging data sets from high resolution imagine science experiment and context imager these data show the lowermost unit of noachian crust in this region is a complex brecciated unit of diverse compositions breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of fe mg phyllosilicates are commonly observed in regions of good exposure layered or banded phyllosilicate bearing breccia rocks are observed suggestive of pre isidis sedimentary deposits in places the phyllosilicate bearing material appears as a matrix surrounding mafic blocks and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin scale ejecta these materials likely include both pre isidis basement rocks as well as the brecciated products of the isidis basin forming event at 3 9 ga a banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of nili fossae to the southern edge of the isidis basin this olivine mafic cap combination superimposes the phyllosilicate bearing basement rocks and distinctly conforms to the underlying basement topography this may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology we interpret the draping superposed olivine mafic cap combination to be impact melt from the isidis basin forming event while some distinct post isidis alteration is evident carbonate kaolinite and serpentine the persistence of olivine from the time of isidis basin suggests that large scale aqueous alteration processes had ceased by the time this unit was emplaced

planetary waves in jupiter s equatorial atmosphere abstract voyager infrared radio occultation and imaging measurements provide a variety of observational evidence and constraints for planetary scale waves latitudinally trapped within jupiter s equatorial jet the visually prominent plumes encircling the planet at 8 deg north latitude show a longitudinal organization of wavenumber n 11 13 an apparently solitary plume also appears at about 8 deg south along the with other smaller periodic cloud features deviations in cloud tracked driff speed including differences in mean values to the north and south of the equator in excess of 25 m sec 1 may be crudely indicative of the magnitude of the associated wave phase speeds radio occultation retrievals of the temperature profiles at two equatorial longitudes show harmonic variation consistent with the stratospheric propagation of two components with vertical wavelengths of approximately 3 and 0 5 scale heights these observations may be consistently interpreted in terms of specific classes of equatorially trapped wave modes the gravest equatorial rossby mode with an equivalent depth of h 2 4 km with a stratospheric wavelength of 3 4 scale heights represents the most consistent interpretation of the plumes the inferred vetical eigenmode could be ducted by a deep statically stable layer possibly imposed by a roughly solar abundant water cloud depending upon the actual details of the moist convection an estimate of the relative growth rates for the near neutral forcing of rossby modes of the inferred equivalent depth implies a maximum for zonal wavenumber 11 the solitary plume feature to the south of the equator may be interpreted as a wavenumber 1 rossby mode with the same vertical scale possibly forced by the interaction between the equatorial jet and the great red spot smaller visual features may correspond to inertia gravity modes with vertical wavelengths comparable to the small harmonic of the occultation profiles galileo orbiter and probe observations will provide an essential test of the wave analysis and substantially enhance its diagnostic utility

spatial distribution of visible lightning on jupiter spacecraft observations have provided evidence for the existence of lightning on venus1 3 jupiter4 5 saturn6 7 and uranus8 little is known however about the global distribution of lightning on these planets because of the limited spatial resolution and areal coverage of these previous detections which have principally involved radio frequency measurements two long exposure images obtained by the voyager 1 spacecraft of a small area on the nightside of jupiter have provided the only previously studied imaging observations of lightning on another planet9 10 here we present an analysis of all suitable voyager images of jupiter and evaluate the horizontal spatial distribution of visible lightning over most of one hemisphere essentially all the detectable activity is confined to very narrow latitude bands at 13 5 n and 49 n the active regions at 49 n are the brightest most numerous and periodic in longitude activity at this latitude is long lived and is most likely associated with moist convective regions deep in jupiter s atmosphere the longitudinal periodicity of the lightning storms may represent the effects of a planetary scale atmospheric wave trapped at the depth of the moist convection11 12

the association of hydrogen with sulfur on mars across latitudes longitudes and compositional extremes nasa jet propulsion lab nasa mars data analysis program nnx07an96g nnx10aq23g mdap grants nnx12ag89g nnx13ai98g lsu s college of science and geology and geophysics

acid sulfate alteration of fluorapatite basaltic glass and olivine by hydrothermal vapors and fluids implications for fumarolic activity and secondary phosphate phases in sulfate rich paso robles soil at gusev crater mars 1 phosphate rich rocks and a nearby phosphate rich soil paso robles were analyzed in gusev crater mars by the mars exploration rover spirit and interpreted to be highly altered possibly by hydrothermal or fumarolic alteration of primary phosphate rich material to test mineral phases resulting from such alteration we performed hydrothermal acid vapor and acid fluid experiments on olivine ol fluorapatite ap and basaltic glass gl as single phases and a mixture of phases minerals formed include ca al fe and mg sulfates with different hydration states anhydrite bassanite gypsum alunogen hexahydrite and pentahydrite phosphate bearing minerals formed included monocalcium phosphate monohydrate mcp acid vapor and acid fluid alteration of fluorapatite only and ferrian giniite acid fluid alteration of the ol gl ap mixture mcp is likely present in paso robles if primary ca phosphate minerals reacted with sulfuric acid with little transport of phosphate under fluid rock ratios allowing transport of phosphate a ferric phosphate phase such as ferrian giniite might form instead mossbauer measurements of ferrian giniite bearing alteration products and synthetic ferrian giniite are consistent with spirit s mossbauer measurements of the ferric bearing phase in paso robes soil but are also consistent with ferric sulfate phases in the low p soil arad samra therefore mossbauer data alone do not constrain the fluid rock ratio however the excess iron hematite in paso robles soil which implies aqueous transport combined with our laboratory experiments suggest acid sulfate alteration in a hydrothermal fumarolic environment at fluid rock ratios sufficient to allow dissolution transport and precipitation of secondary chemical components including a ferric phosphate such as ferrian giniite

sedimentary silica on mars terrestrial planetary surfaces other than earth are overwhelmingly basaltic in character because of this among the most intriguing and significant results from recent studies of mars are the occurrences of high silica rocks at the pathfinder site and orbital thermal emission spectroscopy evidence for a global petrological dichotomy with andesites dominating the entire northern hemispheric plains however during the alteration of basalt under a wide variety of pressure temperature and fluid conditions silica is highly mobile and chemical and or mineralogical relationships among martian soils and other surface deposits suggest the likelihood that sedimentary silica phases would have formed during surficial alteration processes accordingly the redistribution of sedimentary silica needs to be considered in interpreting at least some of the high silica features seen on mars

human adaptive responses to climate and environmental change during the gravettian of lapa do picareiro portugal abstract on the iberian peninsula abrupt climate shifts during the late pleistocene impacted human and natural systems our knowledge of human adaptive responses to these climatic perturbations has improved in recent years with the development of new radiocarbon techniques that have increased the temporal resolution of cultural chronologies at the same time new high resolution paleoclimatic records from greenland ice cores deep sea sediment cores speleothems and microfaunal assemblages have permitted detailed paleoenvironmental reconstructions combined with the archaeological record of culture change these data sets allow for a better understanding of the nature of human socio ecological systems during the late pleistocene here we present new data on the gravettian occupations at lapa do picareiro a cave site in portugal with a long continuous stratigraphic sequence spanning mis 3 and 2 the ongoing excavation of lapa do picareiro has revealed at least three gravettian levels with very different patterns of raw material use and technological reduction the early gravettian levels contain a quartzite flake assemblage with several refitting clusters and a small chert assemblage with nosed endscrapers and bladelet technology the late or terminal gravettian level contains carinated endscraper core bladelet technology mainly quartz with chert blade production and a few bone tools the faunal assemblages also have a different character both contain a similar range of medium and large ungulates but the earlier gravettian has a much richer and more diverse assemblage of small animals these combined archaeological data sets provide a new perspective on gravettian human adaptations in response to climate shifts especially heinrich event 3 and greenland interstadials 4 and 3

cryogenic silicification of microorganisms in hydrothermal fluids silica rich hydrothermal fluids that experience freezing temperatures precipitate cryogenic opal a coa within ice bound brine channels we investigated cryogenic silicification as a novel preservation pathway for chemo and photo lithotrophic bacteria and archaea we find that the co partitioning of microbial cells and silica into brine channels causes microorganisms to become fossilised in coa rod and coccoidal form bacteria and archaea produce numerous cell casts on coa particle surfaces while chloroflexus filaments are preserved inside particle interiors coa particles precipitated from natural icelandic hot spring fluids possess similar biomorphic casts including those containing intact microbial cells biomolecules and inorganic metabolic products are also captured by coa precipitation and are detectable with a combination of visible shortwave infrared reflectance ftir and raman spectroscopy we identify cryogenic silicification as a newly described mechanism by which microbial biosignatures can be preserved within silica rich hydrothermal environments this work has implications for the interpretation of biosignatures in relic hydrothermal settings and for life detection on mars and enceladus where opaline silica indicative of hydrothermal activity has been detected and freezing surface conditions predominate

mid infrared mapping of jupiter s temperatures aerosol opacity and chemical distributions with irtf texes abstract global maps of jupiter s atmospheric temperatures gaseous composition and aerosol opacity are derived from a programme of 5 20 m mid infrared spectroscopic observations using the texas echelon cross echelle spectrograph texes on nasa s infrared telescope facility irtf image cubes from december 2014 in eight spectral channels with spectral resolutions of r 2000 12 000 and spatial resolutions of 2 4 latitude are inverted to generate 3d maps of tropospheric and stratospheric temperatures 2d maps of upper tropospheric aerosols phosphine and ammonia and 2d maps of stratospheric ethane and acetylene the results are compared to a re analysis of cassini composite infrared spectrometer cirs observations acquired during cassini s closest approach to jupiter in december 2000 demonstrating that this new archive of ground based mapping spectroscopy can match and surpass the quality of previous investigations and will permit future studies of jupiter s evolving atmosphere the visibility of cool zones and warm belts varies from channel to channel suggesting complex vertical variations from the radiatively controlled upper troposphere to the convective mid troposphere we identify mid infrared signatures of jupiter s 5 m hotspots via simultaneous m n and q band observations which are interpreted as temperature and ammonia variations in the northern equatorial zone and on the edge of the north equatorial belt neb equatorial plumes enriched in nh3 gas are located south east of nh3 desiccated hotspots on the edge of the neb comparison of the hotspot locations in several channels across the 5 20 m range indicate that these anomalous regions tilt westward with altitude aerosols and ph3 are both enriched at the equator but are not co located with the nh3 plumes the equatorial temperature minimum and ph3 aerosol maxima have varied in amplitude over time possibly as a result of periodic equatorial brightenings and the fresh updrafts of disequilibrium material temperate mid latitudes display a correlation between mid ir aerosol opacity and the white albedo features in visible light i e zones we find hemispheric asymmetries in the distribution of tropospheric ph3 stratospheric hydrocarbons and the 2d wind field estimated via the thermal wind equation that suggest a differing efficiency of mechanical forcing e g vertical mixing and wave propagation between the two hemispheres that we argue is driven by dynamics rather than jupiter s small seasonal cycle jupiter s stratosphere is notably warmer at northern mid latitudes than in the south in both 2000 and 2014 although the latter can be largely attributed to strong thermal wave activity near 30 n that dominates the 2014 stratospheric maps and may be responsible for elevated c2h2 in the northern hemisphere a vertically variable pattern of temperature and windshear minima and maxima associated with jupiter s quasi quadrennial oscillation qqo is observed at the equator in both datasets although the contrasts were more subdued in 2014 large scale equator to pole gradients in ethane and acetylene are superimposed on top of the mid latitude mechanically driven maxima with c2h2 decreasing from equator to pole and c2h6 showing a polar enhancement consistent with a radiatively controlled circulation from low to high latitudes cold polar vortices beyond 60 latitude can be identified in the upper tropospheric and lower stratospheric temperature maps suggesting enhanced radiative cooling from polar aerosols finally compositional mapping of the great red spot confirms the local enhancements in ph3 and aerosols the north south asymmetry in nh3 gas and the presence of a warm southern periphery that have been noted by previous authors

jupiter new estimates of the mean zonal flow at the cloud level abstract previous estimates of the mean zonal flow on jupiter from voyager images by ingersoll et al a p ingersoll r f beebe j l mitchell g w garneau g m yagi and j p mueller 1981 j geophys res 86 8733 8743 and by limaye et al s s limaye h e revercomb l a sromovsky r j krauss v e suomi s a collins and c c avis 1982 j atmos sci 39 1413 1432 showed good agreement in the locations of the easterly and westerly jets but differed somewhat in magnitude recent measurements of the high speed jet located near 24 north plane topographic latitude by t maxworthy 1984 planet space sci 32 1053 1058 from high spatial and temporal resolution voyager images indicate that both ingersoll et al and limaye et al underestimated the magnitude of the jet by more than 30 40 msec 1 in an attempt to examine the differences in the magnitude of the jovian jets determined from voyager 1 and 2 images a new approach to determine the zonal mean east west component of motion was investigated the new technique based on simple digital pattern matching approach and applied on pairs of mapped images cylindrical mosaics yields a profile of the mean zonal component that reproduces the exact locations of the easterly and westerly jets between 60 latitude not only do the jet magnitudes but also the wings of the jets agree remarkably well from mosaic pair to pair further the latitudinal resolution is five midlatitudes to eight times equatorial greater than previous results results have been obtained for all of the voyager 1 and 2 cylindrical mosaics the correlation coefficient between voyager 1 and voyager 2 average mean zonal flow between 60 latitude determined from violet filter mosaics is 0 998 a slight latitude offset possibly due to navigation errors is detectable 0 2 latitude average in the voyager 1 data independent cloud motion measurements in two high resolution image pairs orange and violet acquired from voyager 1 cameras agree well with the average mean zonal flow for the fastest jovian jet at 23 8 n latitude comparison with maxworthy s 1984 results suggests longitudinal variations in cloud motions approaching about 20 msec 1 in particular the jet magnitude is about 163 7 rms msec 1 which compares well with 182 10 msec 1 reported by maxworthy there is excellent agreement in the location of the peak magnitude as well as its shape the time average voyager 2 mean zonal flow profile with latitude is presented in a table

exploring for a record of ancient martian life the immediate task facing exopaleontology is to define a strategy to explore mars for a fossil record during the decade long exploration program that lies ahead consideration of the quality of paleontological information preserved under different geological conditions is important if we are to develop a strategy with broad applicability the preservation of microbial fossils is strongly influenced by the physical chemical and biological factors of the environment which acting together determine the types of information that will be captured and retained in the rock record in detrital sedimentary systems preservation is favored by rapid burial in fine grained clay rich sediments in chemical sedimentary systems preservation is enhanced by rapid entombment in fine grained chemical precipitates for long term preservation host rocks must be composed of stable minerals that are resistant to chemical weathering and that form an impermeable matrix and closed chemical system to protect biosignatures from alteration during subsequent diagenesis or metamorphism in this context host rocks composed of highly ordered chemically stable mineral phases like silica e g cherts or phosphate e g phosphorites are especially favored such lithologies tend to have very long crustal residence times and along with carbonates and shales are the most common host rocks for the precambrian microfossil record on earth although we make the defensible assumption that mars was more like the earth early in its history clearly the geological and historical differences between the two planets are many such differences must be carefully considered when adapting an earth based strategy to mars

deep alteration between hellas and isidis basins abstract recent investigations of alteration of martian crustal outcrops suggest putative crustal hydrothermal systems which are favorable environments for the emergence of life in this study we perform an analysis of the crism targeted observations covering crustal outcrops in the region between the hellas and isidis basins with the goal of investigating the alteration phases over the wide studied region we detect the presence of possible serpentines chlorites smectites and carbonates these detections occur within ejecta blankets crater walls and central uplifts of impact craters we investigate the relation between the observed associations of minerals and the ages of the impact craters assessed by crater count no clear relation is observed we also investigate the relationship between the group of detected mineral and the pre impact depth of the studied outcrops assessed from the size of the impact craters this method allows us to reconstruct the pre impact cross section we suggest that alteration of the first 7 km of the crust between the hellas and isidis basins may have undergone alteration processes

geology and mineralogy of the auki crater tyrrhena terra mars a possible post impact induced hydrothermal system abstract a variety of hydrothermal environments have been documented in terrestrial impact structures due to both past water interactions and meteoritic bombardment on the surface of mars several authors have predicted various scenarios that include the formation of hydrothermal systems geological and mineralogical evidence of past hydrothermal activity have only recently been found on mars here we present a geological and mineralogical study of the auki crater using the spectral and visible imagery data acquired by the crism compact reconnaissance imaging spectrometer for mars ctx context camera and hirise high resolution imaging science experiment instruments on board the nasa mro mission the auki crater is a complex crater that is 38 km in diameter located in tyrrhena terra 96 8 e and 15 7 s and shows a correlation between its mineralogy and morphology the presence of minerals such as smectite silica zeolite serpentine carbonate and chlorite associated with morphological structures such as mounds polygonal terrains fractures and veins suggests that the auki crater may have hosted a post impact induced hydrothermal system although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate rich bedrock units as a consequence of crater formation we favor the hypothesis of impact induced hydrothermal circulation within fractures and subsequent mineral deposition the hydrothermal system could have been active for a relatively long period of time after the impact thus producing a potential transient habitable environment

first measurements of jupiter s zonal winds with visible imaging spectroscopy abstract we present the first measurements of jupiter s wind profile ever obtained with doppler velocity measurements in the visible hitherto knowledge about atmospheric dynamics has been obtained with cloud tracking techniques which consist of tracking visible features from images taken at different dates however cloud tracking indicates the motion of large cloud structures which is an indication of the speed of iso pressure regions rather than the speed of the actual atmospheric particles doppler imaging is as challenging motions are usually less than 100 m s 1 as appealing because it measures the speed of cloud particles instead of large cloud structures significant difference could appear in the case of atmospheric waves interfering with cloud structures here we present the first scientific results of a doppler imaging spectrometer that is dedicated to giant planet seismology and atmospheric dynamics by providing instantaneous line of sight velocity maps of the planets of the solar system the instrument has been developed in the framework of the projects jovial jovian oscillations through velocity images at several longitudes and jive in nm jovian interiors from velocimetry experiment in new mexico it is a fourier transform spectrometer with a fixed optical path difference working in the mid visible domain which monitors the position of solar fraunhofer lines that are reflected in the planets upper atmospheres after describing the instrument principle and the different steps of data reduction we report measurement of the average zonal wind speed of jupiter as a function of latitude from datasets obtained in 2015 and 2016 with two different telescopes when the planet was close to its opposition our results are consistent between the two years we compare the results with wind profiles obtained by cloud tracking on hst hubble space telescope images taken at the same epoch and identify a significant discrepancy in the north equatorial belt and northern part of the equatorial zone

timescales and mechanisms of formation of amorphous silica coatings on fresh basalts at kīlauea volcano hawai i young basalts from k lauea volcano hawai i frequently feature opaque surface coatings 1 80 m thick composed of amorphous silica and fe ti oxides these coatings are the product of interaction of the basaltic surface with volcanically derived acidic fluids previous workers have identified these coatings in a variety of contexts on hawai i but the timescales of coating development coating growth rates and factors controlling lateral coating heterogeneity were largely unconstrained we sampled and analyzed young lava flows of varying ages from hours to 40 years along k lauea s southwest and east rift zones to characterize variation in silica coating properties across the landscape coating thickness varies as a function of flow age flow surface type and proximity to acid sources like local fissure vents and regional plumes emitted from k lauea caldera and pu u silica coatings that form in immediate proximity to acid sources are more chemically pure than those forming in higher ph environments which contain significant al and fe incipient siliceous alteration was observed on basalt surfaces as young as 8 days old but periods of a year or more are required to develop contiguous coatings with obvious opaque coloration inferred coating growth rates vary with environmental conditions but were typically 1 5 m year coatings form preferentially on flow surfaces with glassy outer layers such as spatter ramparts volcanic bombs and dense pahoehoe breakouts due to glass strain weakening during cooling microtextural evidence suggests that the silica coatings form both by in situ dissolution reprecipitation and by deposition of silica mobilized in solution thin films of water acidified by contact with volcanic vapors dissolved near surface basalt then precipitated amorphous silica in place mobilizing more soluble cations additional silica was transported to and deposited on the surface by silica bearing altering fluids derived from the basalt interior

context camera investigation on board the mars reconnaissance orbiter 1 the context camera ctx on the mars reconnaissance orbiter mro is a facility instrument i e government furnished equipment operated by a science team not responsible for design and fabrication designed built and operated by malin space science systems and the mro mars color imager team marci ctx will 1 provide context images for data acquired by other mro instruments 2 observe features of interest to nasa s mars exploration program e g candidate landing sites and 3 conduct a scientific investigation led by the marci team of geologic geomorphic and meteorological processes on mars ctx consists of a digital electronics assembly a 350 mm f 3 25 schmidt type telescope of catadioptric optical design with a 5 7 field of view providing a 30 km wide swath from 290 km altitude and a 5000 element ccd with a band pass of 500 700 nm and 7 m pixels giving 6 m pixel spatial resolution from mro s nearly circular nearly polar mapping orbit raw data are transferred to the mro spacecraft flight computer for processing e g data compression before transmission to earth the ground data system and operations are based on 9 years of mars global surveyor mars orbiter camera on orbit experience ctx has been allocated 12 of the total mro data return or about 3 terabits for the nominal mission this data volume would cover 9 of mars at 6 m pixel but overlapping images for stereo mosaics and observation of changes and meteorological events will reduce this area ctx acquired its first instrument checkout images of mars on 24 march 2006

structural analysis of syn depositional hydrothermal veins of the 3 48 ga dresser formation pilbara craton australia abstract the lower chert unit of the 3 48 ga dresser formation pilbara craton western australia hosts earth s oldest convincing evidence of life in the form of stromatolites in a depositional setting that has been interpreted as either a shallow marine lagoon an active volcanic caldera or a basin deposited during regional extension understanding the environment where early life thrived is important not only for early life studies on earth but in the search for life on mars and for understanding the setting for the origin of life structural analysis of the extensive network of syn depositional hydrothermal chert barite veins that immediately underlies the dresser was undertaken in order to test if deposition occurred within an evolving caldera system or during regional extension over 190 hydrothermal veins were mapped for their geometry and relative age relationships bedding orientations were recorded within nine fault bounded structural sub blocks and used for back rotating the measured veins to their original orientation the results show that 1 there are four main vein systems including three that were emplaced during deposition of the dresser formation lower chert unit and a fourth that was emplaced within syn to post depositional listric growth faults 2 the majority of veins were sub vertical prior to regional tilting 3 the first three vein systems show mutually cross cutting relationships 4 vein densities and the number of vein systems vary between sub blocks 5 conjugate vein networks ne sw and nw se dominate two middle and northern sub blocks these results show that the first three vein systems were emplaced through fracturing under a stress regime with a vertical 1 vertical conjugate fractures are consistent with sandbox models of overburden fracturing during emplacement and discharge of a magma chamber in a volcanic caldera areas of single vein orientations reflect marginal areas of the caldera system dominated by radial or by ring faults the veins in late listric growth faults represent the final period of caldera collapse which controlled the depositional thicknesses of overlying strata possibly during subsequent regional extension these results document an unique setting for earliest life on earth within shallow water and terrestrial deposits of an active low eruptive caldera setting

extensive hydrated silica materials in western hellas basin mars abstract near infrared spectral data indicate the presence of hydrated poorly crystalline silica where high bulk silica contents have been previously identified in hellas basin no other aqueous phases are identified in these regions and the deposits may be nearly pure the silica bearing surfaces are sporadically exposed along a 650 km stretch of the western basin rim within a limited elevation range and display a variety of surface textures suggesting that the materials have been reworked but not transported large distances the high abundances and lack of associated aqueous phases indicate that high water to rock ratios were present in the region during the noachian period but without elevated temperatures or for durations necessary for quartz diagenesis the silica bearing materials may have formed via direct precipitation from silica saturated groundwater sources although other formation mechanisms are also plausible

silica coatings in the ka u desert hawaii a mars analog terrain a micromorphological spectral chemical and isotopic study high silica materials have been observed on mars both from orbit by the crism spectrometer and in situ by the spirit rover at gusev crater these observations potentially imply a wet geologically active martian surface to understand silica formation on mars it is useful to study analogous terrestrial silica deposits we studied silica coatings that occur on the 1974 kilauea flow in the ka u desert hawaii these coatings are typically composed of two layers a 10 m layer of amorphous silica capped by a 1 m layer of fe ti oxide the oxide coating is composed of 100 nm spherules suggesting formation by chemical deposition raman spectroscopy indicates altered silica glass as the dominant phase in the silica coating and anatase and rutile as dominant phases in the fe ti coating jarosite also occurs within the coatings oxygen isotopic contents of the coatings were determined by secondary ion mass spectrometry cameca 7f and nanosims the measured values 18 o fe ti 14 6 2 1 and 18 o silica 12 1 2 2 relative to smow are enriched in 18 o relative to the basalt substrate the observations presented are consistent with a residual formation mechanism for the silica coating acid sulfate solutions leached away divalent and trivalent cations leaving a silica enriched layer behind micrometer scale dissolution and reprecipitation may have also occurred within the coatings chemical similarities between the hawaiian samples and the high silica deposits at gusev suggest that the martian deposits are the product of extended periods of similar acid sulfate leaching

accretionary history and crustal evolution of the variscan belt in western europe abstract the variscan belt of western europe is part of a large intra paleozoic belt extending on both sides of the atlantic from the ouachitas in the us and the mauritanides in west africa to the bohemian massif in czechoslovakia and poland the belt was constructed between 500 and 250 ma as a result of convergence and collision between two main continents laurentia baltica and africa after the closure of various oceanic basins iapetus rheic and galicia massif central now recorded as discrete in part cryptic sutures which form the roots of large crystalline nappes in which are found dismembered remnants of oceanic crust and mantle the accretionary history of the variscan belt in western europe is related to the progressive closure of probably two oceanic basins the rheic in the north and another the galicia massif central in the south by respectively southward and northward intraoceanic subduction followed by obduction and intracontinental lithospheric subduction the result is a broad 700 800 km fan like divergent belt which must be considered as a classical obduction collision orogen with a long intracontinental history of about 100 150 ma its arcuate shape is probably due to the northwestward impingement of a promontory of the african continent into laurentia baltica

amazonian volcanism inside valles marineris on mars the giant trough system of valles marineris is one of the most spectacular landforms on mars yet its origin is still unclear although often referred to as a rift it also shows some characteristics that are indicative of collapse processes for decades one of the major open questions was whether volcanism was active inside the valles marineris here we present evidence for a volcanic field on the floor of the deepest trough of valles marineris coprates chasma more than 130 individual edifices resemble scoria and tuff cones and are associated with units that are interpreted as lava flows crater counts indicate that the volcanic field was emplaced sometime between 0 4 ga and 0 2 ga the spatial distribution of the cones displays a control by trough parallel subsurface structures suggesting magma ascent in feeder dikes along trough bounding normal faults spectral data reveal an opaline silica rich unit associated with at least one of the cones indicative of hydrothermal processes our results point to magma water interaction an environment of astrobiological interest perhaps associated with late stage activity in the evolution of valles marineris and suggest that the floor of coprates chasma is promising target for the in situ exploration of mars

opal a in the nakhla meteorite a tracer of ephemeral liquid water in the amazonian crust of mars the nakhlite meteorites are clinopyroxenites that are derived from a 1300 million year old sill or lava flow on mars most members of the group contain veins of iddingsite whose main component is a fine grained and hydrous fe and mg rich silicate siderite is present in the majority of veins where it straddles or cross cuts the fe mg silicate this carbonate also contains patches of ferric oxy hydroxide despite 40 years of investigation the mineralogy and origins of the fe mg silicate is poorly understood as is the paragenesis of the iddingsite veins nanometer scale analysis of fe mg silicate in the nakhla meteorite by electron and x ray imaging and spectroscopy reveals that its principal constituents are nanoparticles of opal a this hydrous and amorphous phase precipitated from acidic solutions that had become supersaturated with respect to silica by dissolution of olivine each opal a nanoparticle is enclosed within a ferrihydrite shell that formed by oxidation of iron that had also been liberated from the olivine siderite crystallized subsequently and from solutions that were alkaline and reducing and replaced both the nanoparticles and olivine the fluids that formed both the opal a ferrihydrite and the siderite were sourced from one or more reservoirs in contact with the martian atmosphere the last event recorded by the veins was alteration of the carbonate to a ferric oxy hydroxide that probably took place on mars although a terrestrial origin remains possible these results support findings from orbiter and rover based spectroscopy that opaline silica was a common product of aqueous alteration of the martian crust

how flakes shatter a critical evaluation of quartz fracture analysis despite its worldwide use as a stone tool raw material quartz is known to be a difficult material for archaeologists the main reason for this is the tendency of quartz flakes to fragment during detachment which complicates the use of traditional lithic analyses in this article we present an experimental study of quartz flake fragmentation we evaluate the method called fracture analysis that has been developed and used explicitly for the study of quartz assemblages the method assumes high predictability of quartz flake fragmentation but our experiments show that there is significant variation in fragmentation that fracture analysis does not take into account our results indicate that this variation is partly explained by indenter hardness the relative thickness of the detached flake as well as individual knapper related factors these results undermine the applicability of quartz fracture analysis in its current form in addition we discuss the effects of flake fragmentation on the technological organisation of prehistoric quartz users and suggest that it has affected reduction strategies as well as blank and tool dimensions we also suggest that there should be mobility related differences in archaeological assemblages in terms of the quality of the quartz raw material and that the curation of quartz should be low in relation to better quality raw materials used parallel with it

vein quartz in lithic traditions an analysis based on experimental archaeology abstract worldwide vein quartz was a commonly used raw material for stone tools but this material has proved difficult for archaeologists to analyse because many quartz assemblages appear to be comprised of amorphous pieces not easily recognised as humanly modified or forming tools this paper discusses the analysis of the debitage focusing on the debitage fragmentation rate the debitage break and fragment types and the quantitative analysis of the complete flakes resulting from experimental knapping of quartz which formed part of a project which investigated the use of quartz in irish prehistoric lithic traditions the results have highlighted the complexity involved in analysing quartz assemblages and the significant differences between the debitage products of quartz and chert knapping assemblages while bipolar knapping is generally easy to differentiate from direct percussion it is harder to differentiate between soft and hard hammer percussion

dynamics of jupiter s equatorial region at cloud top level from cassini and hst images abstract we present a study of the equatorial region of jupiter between latitudes 15 s and 15 n based on cassini iss images obtained during the jupiter flyby at the end of 2000 and hst images acquired in may and july 2008 we examine the structure of the zonal wind profile and report the detection of significant longitudinal variations in the intensity of the 6 n eastward jet up to 60 m s 1 in cassini and hst observations these longitudinal variations are in the hst case associated with different cloud morphology photometric and radiative transfer analysis of the cloud features used as tracers in hst images show that at most there is only a small height difference no larger than 0 5 1 scale heights between the slow 100 m s 1 and fast 150 m s 1 moving features this suggests that speed variability at 6 n is not dominated by vertical wind shears but instead we propose that rossby wave activity is the responsible for the zonal variability removing this variability we find that jupiter s equatorial jet is actually symmetric relative to equator with two peaks of 140 150 m s 1 located at latitudes 6 n and 6 s and at a similar pressure level we also study the local dynamics of particular equatorial features such as several dark projections associated with 5 m hot spots and a large long lived feature called the white spot ws located at 6 s convergent flow at the dark projections appears to be a characteristic which depends on the particular morphology and has only been detected in some cases the internal flow field in the white spot indicates that it is a weakly rotating quasi equatorial anticyclone relative to the ambient meridionally sheared flow

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

the geological history of nili patera mars nili patera is a 50 km diameter caldera at the center of the syrtis major planum volcanic province the caldera is unique among martian volcanic terrains in hosting i evidence of both effusive and explosive volcanism ii hydrothermal silica and iii compositional diversity from olivine rich basalts to silica enriched units we have produced a new geological map using three mosaicked 18 m pixel context camera digital elevation models supplemented by compact remote imaging spectrometer for mars hyperspectral data the map contextualizes these discoveries formulating a stratigraphy in which nili patera formed by trapdoor collapse into a volcanotectonic depression the distinctive bright floor of nili patera formed either as part of a felsic pluton exposed during caldera formation or as remnants of welded ignimbrite s associated with caldera formation both scenarios deriving from melting in the noachian highland basement after caldera collapse there were five magmatic episodes 1 a basaltic unit in the caldera s north 2 a silica enriched unit and the associated nili tholus cone 3 an intrusive event forming a 300 m high elliptical dome 4 an extrusive basaltic unit emplaced from small cones in the east and 5 an extreme olivine bearing unit formed on the western caldera ring fault the mapping together with evidence for hydrated materials implies magmatic interaction with subsurface volatiles this in an area of elevated geothermal gradient presents a possible habitable environment sampled by the hydrothermal deposits additionally similarities to other highland volcanoes imply similar mechanisms and thus astrobiological potential within those edifices

geology of quartz and hydrated silica bearing deposits near antoniadi crater mars 1 the only area on mars where crystalline quartz has been identified from orbit is near antoniadi crater on the northern edge of the syrtis major shield volcano however the method of quartz formation has remained unknown in this study we use high resolution satellite imagery as well as thermal and near infrared spectroscopy to construct a geologic history of these deposits and their local context we find that the quartz bearing deposits are consistently co located with hydrated silica this spatial coherence suggests that the quartz formed as a diagenetic product of amorphous silica rather than as a primary igneous mineral diagenetic quartz is a mature alteration product of hydrated amorphous silica and indicates more persistent water and or higher temperatures at this site beneath the silica bearing rocks we also find spectral evidence for smectites in the lowermost exposed noachian aged breccia a similar stratigraphic sequence smectite bearing breccias beneath deposits containing minerals suggesting a greater degree of alteration has also been found at nearby exposures at nili fossae and toro crater suggesting a widespread sequence of alteration by merging the mineral detections of thermal infrared quartz feldspar and near infrared spectroscopy hydrated silica smectite clays we are able to construct a more complete geologic history from orbit

the effect of solution chemistries and freezing temperatures on the morphology of cryogenic opal a coa implications for past climates on mars abstract cryogenic opal a coa is a type of hydrated amorphous silica that forms when silica rich geothermal fluids erupt sub aerially and are exposed to air temperatures below 0 c as the fluid cools and water ice forms the solution increases in ionic strength and reaches saturation of opal a this results in the precipitation of opal a between water ice crystals natural coa is found embedded within frozen fluids near hydrothermal sources and has been shown to preserve signs of biological activity in this study two solution chemistries hydrochloric acid hcl and sulfuric acid h2so4 and three freezing temperatures 20 80 196 c were used to synthesize coa in the lab sem analyses showed that coa frozen at 20 c in hcl solutions produced smooth silica branches similar to what was observed in previous studies coa precipitated at lower freezing temperatures demonstrated progressively smaller particle sizes and unique morphologies such as halite dendrites within silica desiccation cracks and pores coa made in h2so4 solutions was more angular and fragmented than coa made in hcl solutions particle size also decreased with decreasing freezing temperature coa textures have implications for terrestrial samples as well as future samples returned from mars because they can provide information about past climate and fluid chemistry plain language summary cryogenic opal a coa is a hydrous silicate material that can form when geysers and hot springs erupt and are exposed to air temperatures below 0 c coa forms in brine veins that are between water ice crystals and takes the shape of the veins in which they form coa has been shown to preserve signs of biological activity in this study two solution chemistries hydrochloric acid hcl and sulfuric acid h2so4 and three freezing temperatures 20 80 196 c were used to form coa in the lab scanning electron microscope analyses showed that in general coa particle size decreased with decreasing freezing temperature additionally coa made in hcl solutions were smooth and tubular whereas coa made in h2so4 solution were angular and fragmented coa textures have implications for terrestrial samples as well as future samples returned from mars because they can provide information about past climate and fluid chemistry

visible near infrared and mid infrared spectral characterization of hawaiian fumarolic alteration near kilauea s december 1974 flow implications for spectral discrimination of alteration environments on mars

dynamics of the atmospheres of the outer planets post voyager measurement objectives current knowledge about dynamics and thermal structure on the outer planets is reviewed with the aim of identifying important measurements which should be made in the post voyager era the existence of jets and cloud bands is the puzzle that underlies all others discussion focuses on the particular case of jupiter because documentation is most complete recent dynamical work has successfully reproduced much of the behavior of jets and spots with simple models that contain few parameters it is argued that the gross dynamical parameters such as density stratification and rotation rate are the keys to their behaviors rather than the particular specifics of radiative forcing cloud distributions thermodynamic transformations voyager data have shown that the jet systems decay with height in the region above the visible clouds therefore the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds these require determination of the deep structure of the jets of the density stratification and of the horizontal density contrasts the deep regions are not easily accessible and these measurements present challenging opportunities indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere and some of these issues are also discussed

jupiter s equatorial plumes and hot spots spectral mapping from gemini texes and juno mwr we present multi wavelength measurements of the thermal chemical and cloud contrasts associated with the visibly dark formations also known as 5 m hot spots and intervening bright plumes on the boundary between jupiter s equatorial zone ez and north equatorial belt neb observations made by the texes 5 20 m spectrometer at the gemini north telescope in march 2017 reveal the upper tropospheric properties of 12 hot spots which are directly compared to measurements by juno using the microwave radiometer mwr jiram at 5 m and juno cam visible images mwr and thermal infrared spectroscopic results are consistent near 0 7 bar mid infrared derived aerosol opacity is consistent with that inferred from visible albedo and 5 m opacity maps aerosol contrasts the defining characteristics of the cloudy plumes and aerosol depleted hot spots are not a good proxy for microwave brightness the hot spots are neither uniformly warmer nor ammonia depleted compared to their surroundings at p 10 bars suggesting that the hot spot plume wave is a relatively shallow feature plain language summary to date our only direct measurement of jupiter s gaseous composition came from the descent of the galileo probe in 1995 however the results from galileo appeared to be biased due to the unusual meteorological conditions of its entry location a dark cloud free region just north of the equator known as a hot spot one of the aims of nasa s juno mission was to place the findings of the galileo probe into broader con text which requires a detailed characterisation of these equatorial hot spots and their neighbouring plumes we combine a data from juno microwave observations sounding conditions below the clouds and visible infrared observations revealing variations in cloud opacity with b observations from amateur observers to track the hot spots over time and c observations from the texes infrared spectrometer mounted on the gemini north telescope the latter provides the highest resolution thermal maps of jupiter s tropics ever obtained and reveals contrasts within and between the individual hot spots and plumes we find that the hot spots are distinguishable from their surroundings for relatively shallow pressures but that the deep measurements from juno and galileo are probably more representative of jupiter s north equatorial belt than previously thought

meteorology of jupiter s equatorial hot spots and plumes from cassini we present an updated analysis of jupiter s equatorial meteorology from cassini observations for two months preceding the spacecraft s closest approach the imaging science subsystem iss onboard regularly imaged the atmosphere we created time lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes hot spots are relatively cloud free regions that emit strongly at 5 lm improved knowledge of these features is crucial for fully understanding galileo probe measurements taken during its descent through one hot spots are quasistable rectangular dark areas on visible wavelength images with defined eastern edges that sharply contrast with surrounding clouds but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes hot spots exhibit significant variations in size and shape over timescales of days and weeks some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots impressive bright white plumes occupy spaces in between hot spots compact cirrus like scooter clouds flow rapidly through the plumes before disappearing within the dark areas these clouds travel at 150 200 m s 1 much faster than the 100 m s 1 hot spot and plume drift speed this raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip if a downward branch of an equatorially trapped rossby wave controls the overall appearance of hot spots however the westward phase velocity of the wave leads to underestimates of the true jet stream speed

the use of quartz during the upper paleolithic and early mesolithic in sabor valley nw iberia the foz do medal case abstract the use of quartz is well documented during prehistory being the predominant raw material in the upper paleolithic sites located in nw iberia the prehistoric occupations from sabor valley also present a preference for this lithology through the long occupation sequence although a large range of regional and exogenous lithic raw materials are also knapped within the quartz varieties rock crystal seems to have an important role in some chronologies especially since the solutrean phase regarding elongated products and small flake production several reduction strategies were applied to rock crystal although the unifacial exploitation from a 45 degree striking platform using the crystal natural edges as guidelines is the most common though there are some similarities within the use of this type of cores throughout the chronological sequence we can observe some differences especially during the early mesolithic phase in a regional perspective it is possible to compare the quartz economy from occupations in sabor valley to the ones from coa valley to the south and discuss the role of rock crystal in late pleistocene inland human groups it is clear that there was a technical ability to maximize a local lithic resource such as rock crystal which was exploited in order to achieve blanks similar to those obtained from flint cores

the geologic history of margaritifer basin mars in this study we investigate the fluvial sedimentary and volcanic history of margaritifer basin and the uzboi ladon morava outflow channel system this network of valleys and basins spans more than 8000 km in length linking the fluvially dissected southern highlands and argyre basin with the northern lowlands via ares vallis compositionally thermophysically and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in margaritifer basin our analyses show that fluvial activity was separated in time by significant episodes of geologic activity including the widespread volcanic resurfacing of margaritifer basin and the formation of chaos terrain the most recent fluvial activity within margaritifer basin appears to terminate at a region of chaos terrain suggesting possible communication between surface and subsurface water reservoirs we conclude with a discussion of the implications of these observations on our current knowledge of martian hydrologic evolution in this important region

revised crism spectral parameters and summary products based on the currently detected mineral diversity on mars the investigation of hyperspectral data from the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism and the observatoire pour la mineralogie l eau les glaces et l activitie omega on mars express has revealed an increasingly diverse suite of minerals present on the martian surface a revised set of 60 spectral parameters derived from corrected spectral reflectance at key wavelengths in crism targeted observations and designed to capture the known diversity of surface mineralogy on mars is presented here as summary products some of the summary products have strong heritage to omega spectral parameter calculations this paper also presents newly derived parameters that highlight locations with more recently discovered spectral signatures type locations for the diversity of currently identified mineral spectral signatures have been compiled into a library presented in this work our analysis indicates that the revised set of summary products captures the known spectral diversity of the surface and successfully highlights and differentiates between locations with differing spectral signatures the revised spectral parameter calculations and related products provide a useful tool for scientific interpretation and for future mission landing site selection and operations

a systematic mapping procedure based on the modified gaussian model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars clenet et al 2011 have developed an adapted version of the modified gaussian model mgm the improvements allow the characterization of spectra of olivine pyroxene s mixtures addressing both modal composition and individual minerals chemical composition this version of mgm is fully automated and operational with large amounts of hyperspectral imaging data two natural cases are considered the first one is the sumail massif in the oman ophiolite earth based on our approach applied to hymap data two contrasted lithologic units are mapped the mantle which is harzburgite dominated and the crust made of gabbros and clinopyroxene rich cumulates with spectral variations interpreted in terms of pyroxenes chemical compositions once this new mgm mapping approach has been validated on a controlled natural situation we map the distribution of mafic assemblages across the syrtis major volcano on mars using a visible and near infrared vnir short wave infrared swir observatoire pour la mineralogie l eau les glaces et l activite omega mars express mex mosaic our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice especially in ternary mafic assemblages augite olivine enstatite based on these results we propose a possible scenario for the igneous and thus thermal evolution of the syrtis major region surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the noachian crust we also observe variations in the mineral assemblages within syrtis major lavas which can be interpreted in terms of differentiation from a common parent melt and or of a progressive evolution of the mantle source composition and temperature key points mgm systematic mapping on syrtis major to characterize mafic minerals mixtures olivine and pyroxenes mixture is detected in the central lavas of the volcano pyroxenes have chemical compositions spanning the enstatite augite range

acid sulfate weathering of synthetic martian basalt the acid fog model revisited the acid fog model has received considerable attention as a model of soil formation on mars previous evaluations of this model have focused on experimental weathering of terrestrial basalt samples however these samples differ significantly from what now is thought to be typical of martian basalt the acid fog model is tested here using synthetic basaltic analogs derived from mars pathfinder soil and rock compositions reaction of synthetic basalt with various acidic solutions and subsequent evaporation has led to the formation of several putative secondary mineral phases many of these phases were not produced in prior experimental studies aimed at aqueous interactions on mars of these alteration phases mg fe ca and al sulfates were identified in addition secondary ferric oxide phases formed via rapid fe oxidation under relatively high ph levels buffered by basalt dissolution amorphous silica is a ubiquitous product in these experiments and has formed by precipitation from solution and by the dissolution of minerals and glasses leaving behind leached surface layers composed of residual silica the secondary products formed in these experiments demonstrate the importance of primary mineralogy when testing models of aqueous interactions on mars new constraints are placed on both the reactivity of primary basalt and the secondary mineralogy present at the martian surface copyright 2004 by the american geophysical union

a multidisciplinary overview of the lower mino river terrace system nw iberian peninsula abstract the mino river basin represents one of the main fluvial catchments draining the atlantic side of the iberian peninsula the extensive sedimentary deposits of this basin have been documented since the 19th century but limited research has been undertaken on these features historically and the quaternary record of the basin has remained understudied until recently research carried out over the last decade on the spanish margin of the mino river has enabled more detailed classification and mapping of the main fluvial landforms as well as numerical luminescence electron spin resonance cosmogenic dating of some of the deposits associated with palaeolithic archaeological sites here we synthesise the existing quaternary fluvial record for the basin and present new geospatial and chronological analyses for the lower catchment area our latest examination has enabled the identification of nine fluvial terrace levels and other regionally significant sedimentary features e g alluvial fans formed in response to tectonics eustatic changes and associated global climate changes the chronological data and calculated incision rates indicate that the various fluvial terraces were formed during the early to late pleistocene numerous palaeolithic sites have been found in association with the middle terrace levels between 40 and 13 m above present day river level primarily these archaeological sites preserve assemblages that feature large flake acheulean lfa tools though a number of middle palaeolithic sites have also been documented direct dating of these sites together with morphostratigraphic correlations across the terrace system suggest that the basin has been extensively occupied by human populations during the last 300 thousand years

a field guide to finding fossils on mars the martian surface is cold dry exposed to biologically harmful radiation and apparently barren today nevertheless there is clear geological evidence for warmer wetter intervals in the past that could have supported life at or near the surface this evidence has motivated national aeronautics and space administration and european space agency to prioritize the search for any remains or traces of organisms from early mars in forthcoming missions informed by 1 stratigraphic mineralogical and geochemical data collected by previous and current missions 2 earth s fossil record and 3 experimental studies of organic decay and preservation we here consider whether how and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early mars we conclude that noachian hesperian fe bearing clay rich fluvio lacustrine siliciclastic deposits especially where enriched in silica currently represent the most promising and best understood astropaleontological targets siliceous sinters would also be an excellent target but their presence on mars awaits confirmation more work is needed to improve our understanding of fossil preservation in the context of other environments specific to mars particularly within evaporative salts and pore fracture filling subsurface minerals

open air gravettian lithic assemblages from northeast portugal the foz do medal site sabor valley abstract recent works undertaken in sabor valley northeast portugal revealed an important upper paleolithic sequence to the north of douro river in a region with little paleolithic evidence previous upper paleolithic occupation evidence in the region had only been identified and studied in coa valley to the south of douro river foz do medal site is located in an interior area of iberia on the fringe of the spanish meseta in the transition to the atlantic facade the work accomplished allowed the identification of gravettian levels the gravettian lithic assemblage from foz do medal presents different characteristics when compared with other more traditional gavettian assemblages namely from portuguese estremadura although sharing some features the objectives of the reduction and the strategies applied show big peculiarities which can be related mainly with the geological context and the raw material sources the scarcity of biogenic chert and the availability of other local siliceous rocks such as hydrothermal cherts rock crystal and other types of fine quartz have played a major role in the choices made by prehistoric humans quartz in its several varieties was the chosen raw material for knapping reaching more that 80 of the total collection as a result the regional environmental context and human strategies show great variability between foz do medal and coa valley gravettian assemblages and other gravettian assemblages where chert is easily available

in situ compositions of martian volcanics implications for the mantle the primary objective of this analysis is to determine the mineralogic composition of relatively pristine terrains exposed on the surface of mars this analysis is conducted using imaging spectrometer data acquired in 1989 by the imaging spectrometer for mars ism instrument that was onboard the phobos ii spacecraft the ism instrument acquired some of the highest spectral 64 channels between 0 77 and 3 14 m and spatial resolution 22 km pixel observations to date of mars focused on the equatorial region relatively unaltered surfaces were identified in these data on the basis of their spectral properties low albedo weak spectral slope absence of ferric absorptions and were found in volcanic terrains of syrtis major valles marineris ophir planum and sinus meridiani oxia palus spectra representative of the diversity among terrains were extracted for detailed analysis using the modified gaussian model to determine the primary mafic mineralogy it was determined that the mafic mineralogy of the regions investigated is dominated by low calcium and high calcium pyroxene lcp hcp and that there was homogeneity within a given region but some heterogeneity between regions in the relative abundance of lcp to hcp the two pyroxene mineralogy is consistent with the mineralogies of the basaltic snc meteorites believed to have originated on mars two pyroxene volcanic mineralogies are indicative of large degrees of partial melting e g komatiites or a mantle source depleted in aluminum integration of these findings with previous studies of mars and the snc meteorites indicates that 1 the snc mineralogies are representative of large volcanic regions of mars with surface ages as old as 2 3 ga 2 the martian mantle was depleted in aluminum at least as long ago as the oldest terrain analyzed ophir planum and 3 there has been little evolution in the composition of mantle source regions as the 180 ma snc mineralogies are comparable to those of the oldest terrains analyzed

hapke mixture modeling applied to vnir spectra of mafic mineral mixtures and shergottites implications for quantitative analysis of satellite data 2018 the authors meteoritics planetary science published by wiley periodicals inc on behalf of the meteoritical society met this is an open access article under the terms of the creative commons attribution license which permits use distribution and reproduction in any medium provided the original work is properly cited

paleolithic socionatural relationships during mis 3 and 2 in central portugal abstract throughout the pleistocene climatic shifts repeatedly impacted the mediterranean region in response to these perturbations the mediterranean bioclimatic zones evolved as some of the most diverse dynamic and resilient in the world the appearance of modern humans in western iberia 30 35 ka co occurred with important environmental changes especially regarding animal communities these transformations are associated with the onset of mis 2 and introduction of new land use practices combined data from zooarchaeological paleontological and paleovegetation records are used to identify patterns in human environment interaction at different spatial and temporal scales evidence suggests that humans modified their environment creating long term dynamic and resilient socionatural systems during the upper paleolithic

convective growth rates of equatorial features in the jovian atmosphere the first results of measurements of divergence and vertical velocity of cloud features in the atmosphere of jupiter are presented from analyses of voyager images performed using the interactive planetary imaging processing system at university college london active equatorial plumes are found to have typical divergences of 1 2 10 5s 1 and vertical velocities of 20 40 cm s 1 during the observational periods examined these plumes are considerably more active than the bright albedo features in the turbulent regions of the jovian north and south equatorial belts

identification and description of a silicic volcaniclastic layer in gale crater mars using active neutron interrogation the dynamic albedo of neutrons instrument aboard the mars science laboratory rover curiosity has been used to map a stratigraphically conformable layer of high sio material in gale crater previous work has shown that this material contains tridymite a high temperature low pressure felsic mineral interpreted to have a volcanic source rock we describe several characteristics including orientation extent hydration and geochemistry consistent with a volcaniclastic material conformably deposited within a lacustrine mudstone succession relationships with widely dispersed alteration features and orbital detections of hydrated sio suggest that this high sio layer extends at least 17 km laterally mineralogical abundances previously reported for this high sio material indicated that hydrous species were restricted to the amorphous non crystalline fraction which is dominated by sio the low mean bulk hydration of this high sio layer 1 85 0 13 wt water equivalent hydrogen is consistent with silicic glass in addition to opal a and opal ct persistent volcanic glass and tridymite in addition to opal in an ancient sedimentary unit indicates that the conversion to more ordered forms of crystalline sio has not proceeded to completion and that this material has had only limited exposure to water since it originally erupted despite having been transported in a fluviolacustrine system our results including the conformable nature large areal extent and presence of volcanic glass indicate that this high sio material is derived from the product of evolved magma on mars this is the first identification of a silicic volcaniclastic layer on another planet and has important implications for magma evolution mechanisms on single plate planets

equatorial waves in the stratosphere of uranus abstract we have identified and characterized an equatorial wave in the stratosphere of uranus through analysis of radio occultation data from voyager 2 our methodology relies on two physical phenomena 1 atmospheric waves modulate the ambient background structure of a planetary atmosphere producing a distinctive pattern of spatial variations in temperature and density and 2 this type of spatial modulation in turn causes fluctuations in the phase and amplitude of radio signals received from an occulted spacecraft we compared predictions of the linear theory for equatorial waves on a plane with observations of the stratosphere at both immersion 2 0 n 342 2 e and emersion 6 3 n 197 5 e note that the latitude system used here is the reverse of the iau convention the observed quasi periodic vertical variations in atmospheric density agree closely with theoretical predictions for a wave propagating vertically through the observed background structure of the stratosphere providing compelling evidence for the presence of an atmospheric wave the wave has an equivalent depth of 53 12 m a vertical wavelength of about one third of a pressure scale height and an amplitude at the 1 mbar pressure level at immersion emersion of 1 1 0 4 k 0 5 0 2 k within the framework of the linear wave theory quantitative comparisons between the measurements at immersion and emersion yielded constraints on the meridional and zonal structure of the wave the ratio of amplitudes at the two locations 2 1 0 3 is consistent with a wave confined in latitude near the equator moreover the observations at immersion and emersion are correlated suggesting a wave of planetary scale these constraints allowed us to identify two equatorial wave modes as equally likely alternatives for explaining the observations each retains a relatively simple spatial structure while accounting for the principal features of the data the first is an inertia gravity wave with westward zonal phase speed relative to the mean zonal winds a meridional index j 1 and a zonal wavenumber n 6 the second is an eastward inertia gravity wave with j 2 and n 14 all kelvin yanai and rossby wave modes are inconsistent with the observations we expect the wave to begin breaking near the 200 bar pressure level resulting in an eddy diffusion coefficient of about 0 6 to 1 0 10 4 cm 2 sec 1 consistent with independent estimates of this parameter vertical transfer of momentum by the wave could accelerate the mean zonal wind at pressures less than 200 bar by about 10 20 cm sec 1 per planet rotation

changes in jupiter s zonal velocity between 1979 and 2008 abstract we show that the peak velocity of jupiter s visible cloud level zonal winds near 24 n planetographic increased from 2000 to 2008 this increase was the only change in the zonal velocity from 2000 to 2008 for latitudes between 70 that was statistically significant and not obviously associated with visible weather we present the first automated retrieval of fast 130 m s 1 zonal velocities at 8 n planetographic latitude and show that some previous retrievals incorrectly found slower zonal winds because the eastward drift of the dark projections associated with 5 m hot spots fooled the retrieval algorithms we determined the zonal velocity in 2000 from cassini images from nasa s planetary data system using a global method similar to previous longitude shifting correlation methods used by others and a new local method based on the longitudinal average of the two dimensional velocity field we obtained global velocities from images acquired in may 2008 with the wide field planetary camera 2 wfpc2 on the hubble space telescope hst longer term variability of the zonal winds is based on comparisons with published velocities based on 1979 voyager 2 and 1995 1998 hst images fluctuations in the zonal wind speeds on the order of 10 m s 1 on timescales ranging from weeks to months were found in the 1979 voyager 2 and the 1995 1998 hst velocities in data separated by 10 h we find that the east west velocity uncertainty due to longitudinal fluctuations are nearly 10 m s 1 so velocity fluctuations of 10 m s 1 may occur on timescales that are even smaller than 10 h fluctuations across such a wide range of timescales limit the accuracy of zonal wind measurements the concept of an average zonal velocity may be ill posed and defining a temporal mean zonal velocity as the average of several zonal velocity fields spanning months or years may not be physically meaningful at 8 n we use our global method to find peak zonal velocities of 110 m s 1 in 2000 and 130 m s 1 in 2008 zonal velocities from 2000 cassini data produced by our local and global methods agree everywhere except in the vicinity of 8 n there the local algorithm shows that the east west velocity has large variations in longitude vast regions exceed 140 m s 1 our global algorithm and all of the velocity extraction algorithms used in previously published studies found the east west drift velocities of the visible dark projections rather than the true zonal velocity at the visible cloud level therefore the apparent increase in zonal winds between 2000 and 2008 at 8 n is not a true change in zonal velocity at 7 3 n the galileo probe found zonal velocities of 170 m s 1 at the 3 bar level if the true zonal velocity at the visible cloud level at this latitude is 140 m s 1 rather than 105 m s 1 then the vertical zonal wind shear is much less than the currently accepted value

silica in a mars analog environment ka u desert kilauea volcano hawaii airborne visible near infrared imaging spectrometer aviris data acquired over the ka u desert are atmospherically corrected to ground reflectance and used to identify the mineralogic components of relatively young basaltic materials including 250 700 and 200 400 year old lava flows 1971 and 1974 flows ash deposits and solfatara incrustations to provide context a geologic surface units map is constructed verified with field observations and supported by laboratory analyses aviris spectral end members are identified in the visible 0 4 to 1 2 m and short wave infrared 2 0 to 2 5 m wavelength ranges nearly all the spectral variability is controlled by the presence of ferrous and ferric iron in such minerals as pyroxene olivine hematite goethite and poorly crystalline iron oxides or glass a broad nearly ubiquitous absorption feature centered at 2 25 m is attributed to opaline amorphous hydrated silica and is found to correlate spatially with mapped geologic surface units laboratory analyses show the silica to be consistently present as a deposited phase including incrustations downwind from solfatara vents cementing agent for ash duricrusts and thin coatings on the youngest lava flow surfaces a second ti rich upper coating on young flows also influences spectral behavior this study demonstrates that secondary silica is mobile in the ka u desert on a variety of time scales and spatial domains the investigation from remote field and laboratory perspectives also mimics exploration of mars using orbital and landed missions with important implications for spectral characterization of coated basalts and formation of opaline silica in arid acidic alteration environments

a unique volcanic field in tharsis mars pyroclastic cones as evidence for explosive eruptions based on theoretical grounds explosive basaltic volcanism should be common on mars yet the available morphological evidence is sparse we test this hypothesis by investigating a unique unnamed volcanic field north of the shield volcanoes biblis patera and ulysses patera on mars where we observe several small conical edifices and associated lava flows twenty nine volcanic cones are identified and the morphometry of many of these edifices is determined using established morphometric parameters such as basal width crater width height slope and their respective ratios their morphology morphometry and a comparison to terrestrial analogues suggest that they are martian equivalents of terrestrial pyroclastic cones the most common volcanoes on earth the cones are tentatively interpreted as monogenetic volcanoes according to absolute model age determinations they formed in the amazonian period our results indicate that these pyroclastic cones were formed by explosive activity the cone field is superposed on an old elevated window of fractured crust which survived flooding by younger lava flows it seems possible that a more explosive eruption style was common in the past and that wide spread effusive plain style volcanism in the late amazonian has buried much of its morphological evidence in tharsis

feldspathic rocks on mars compositional constraints from infrared spectroscopy and possible formation mechanisms rare feldspar dominated surfaces on mars were previously reported based on near infrared nir spectral data and were interpreted to consist of anorthosite or felsic rocks using thermal infrared tir data over the feldspar detections with the largest areal extent in nili patera and noachis terra we rule out felsic interpretations basaltic or anorthositic compositions are consistent with tir measurements but the geologic contexts for these regions do not support a plutonic origin laboratory nir spectral measurements demonstrate that large plagioclase crystals 840 m can be detected in mixtures with as much as 50 vol mafics which is higher than the previously stated requirement of no more than 15 mafics thus anorthositic or felsic interpretations need not be invoked for all nir based feldspar detections plagioclase enriched basaltic eruptive products can be formed from martian basalts through partial crystallization at the base of a thick crust followed by low pressure crystallization of the residual liquids

acid fog deposition at kilauea volcano a possible mechanism for the formation of siliceous sulfate rock coatings on mars on the summit of kilauea volcano sulfur dioxide which is continuously emitted from halemaumau crater and rapidly sequestered into sulfuric acid rich aerosol entrained in the prevailing trade winds is subsequently precipitated as acid fog immediately downwind from kilauea caldera in the kau desert the characteristic ph of surface tephra deposits is 4 0 in sand wash a region of nearly continuous acidic aerosol fallout immediately southwest of the caldera vertical exposures of unconsolidated tephras of the keanakakoi ash found within fissures and small dry gullies are coated with thin rock coatings of amorphous silica and jarosite these rock coatings are formed via an evaporative mechanism whereby acidic pore fluids circulating in the upper few meters within the highly porous tephra are wicked toward the walls of the gullies geochemical modeling of the rock coating formation process implies that the sulfate formation via evaporation occurs subsequent to minimal interaction of acidic pore fluids with the basaltic tephra this also suggests that the cycle from acid fog fallout to precipitation of the siliceous sulfate rock coatings must occur quite rapidly acid fog deposition of sulfate and silica at kilauea may provide one mechanism for the origin of jarosite bearing outcrops on mars

hydrous minerals on mars as seen by the crism and omega imaging spectrometers updated global view 1 the surface of mars has preserved the record of early environments in which its basaltic crust was altered by liquid water these aqueous environments have survived in the form of hydrological morphologies and alteration minerals including clays and hydrated salts because these minerals probe on earth aqueous environments compatible with biotic activity understanding their formation processes on mars is of great exobiological relevance and also offers insight into earth s now erased ancient water environments using remote sensing we conducted a large scale investigation of the distribution composition age and geomorphic settings of hydrous minerals on mars providing a sharpened global view of the early aqueous environments and their evolution with time aqueous alteration seems to have produced clays on a planetary scale but these are found to be restricted to the oldest observable terrains on mars 4 gyr however very diverse aqueous environments have also been found which suggest widespread complex aqueous settings from the surface to kilometric depths and spanning over 1 gyr by building a robust statistical sample of detections the global trends inferred here attempt to provide a broad view of our current understanding of hydrous minerals on mars and provide context for more localized in depth analyses collectively these trends suggest that at least transient conditions have existed on mars which may have been favorable for pre biotic to biotic activity

analysis of neptune s 2017 bright equatorial storm abstract we report the discovery of a large 8500 km diameter infrared bright storm at neptune s equator in june 2017 we tracked the storm over a period of 7 months with high cadence infrared snapshot imaging carried out on 14 nights at the 10 m keck ii telescope and 17 nights at the shane 120 inch reflector at lick observatory the cloud feature was larger and more persistent than any equatorial clouds seen before on neptune remaining intermittently active from at least 10 june to 31 december 2017 our keck and lick observations were augmented by very high cadence images from the amateur community which permitted the determination of accurate drift rates for the cloud feature its zonal drift speed was variable from 10 june to at least 25 july but remained a constant 237 4 0 2 m s 1 from 30 september until at least 15 november the pressure of the cloud top was determined from radiative transfer calculations to be 0 3 0 6 bar this value remained constant over the course of the observations multiple cloud break up events in which a bright cloud band wrapped around neptune s equator were observed over the course of our observations no dark spot vortices were seen near the equator in hst imaging on 6 and 7 october the size and pressure of the storm are consistent with moist convection or a planetary scale wave as the energy source of convective upwelling but more modeling is required to determine the driver of this equatorial disturbance as well as the triggers for and dynamics of the observed cloud break up events

the reflectance spectra of opal a 0 5 25 μm from the taupo volcanic zone spectra that may identify hydrothermal systems on planetary surfaces 1 opal a the main component of siliceous sinters in many terrestrial hydrothermal systems is a hydrated silicate that commonly incorporates silicified microorganisms the detection of opal a on the surface of mars therefore may carry important implications in the search for extraterrestrial life sinters from the discharge apron of ohaaki pool north island new zealand yielded reflectance spectra wavelengths between 0 5 25 m that indicate the presence of absorbed water trapped water and silanol in opal a two classes 1 and 2 of reflectance spectra were detected between the wavelengths of 6 13 m the class 1 spectrum is similar to existing opal spectra and was collected from well consolidated samples that had low porosity the class 2 spectrum is unique when compared to the spectra of other silica polymorphs and was collected from poorly consolidated samples that had high porosity

sonar equations for planetary exploration the set of formulations commonly known as the sonar equations have for many decades been used to quantify the performance of sonar systems in terms of their ability to detect and localize objects submerged in seawater the efficacy of the sonar equations with individual terms evaluated in decibels is well established in earth s oceans the sonar equations have been used in the past for missions to other planets and moons in the solar system for which they are shown to be less suitable while it would be preferable to undertake high fidelity acoustical calculations to support planning execution and interpretation of acoustic data from planetary probes to avoid possible errors for planned missions to such extraterrestrial bodies in future doing so requires awareness of the pitfalls pointed out in this paper there is a need to reexamine the assumptions practices and calibrations that work well for earth to ensure that the sonar equations can be accurately applied in combination with the decibel to extraterrestrial scenarios examples are given for icy oceans such as exist on europa and ganymede titan s hydrocarbon lakes and for the gaseous atmospheres of for example jupiter and venus

silica deposits in the nili patera caldera on the syrtis major volcanic complex on mars the martian surface features abundant volcanoes and evidence for past liquid water extant or relict martian volcanic hydrothermal systems have therefore been sought in the pursuit of evidence for habitable environments the mars exploration rover spirit detected deposits highly enriched in silica with accessory minerals suggesting formation by hydrothermal leaching of basaltic rocks by low ph solutions however extensive erosion has obscured the context of the formation environment of these deposits silica deposits have also been identified remotely but also with limited contextual clues to their formation aqueous alteration products of basalt and volcanic ash are the most likely sources here we report the detection from orbit of hydrated silica deposits on the flanks of a volcanic cone in the martian syrtis major caldera complex near infrared observations show dozens of localized hydrated silica deposits as a result of the morphology of these deposits and their location in and around the cone summit we suggest that the deposits were produced by a volcanically driven hydrothermal system the cone and associated lava flows post date early hesperian volcano formation we conclude that if a relict hydrothermal system was associated with the silica deposits it may preserve one of the most recent habitable microenvironments on mars

dynamical implications of jupiter s tropospheric ammonia abundance abstract groundbased radio observations indicate that jupiter s ammonia is globally depleted from 0 6 bars to at least 4 6 bars relative to the deep abundance of 3 times solar a fact that has so far defied explanation the observations also indicate that i the depletion is greater in belts than zones and ii the greatest depletion occurs within jupiter s local 5 m hot spots which have recently been detected at radio wavelengths here we first show that both the global depletion and its belt zone variation can be explained by a simple model for the interaction of moist convection with jupiter s cloud layer circulation if the global depletion is dynamical in origin then important endmember models for the belt zone circulation can be ruled out next we show that the radio observations of jupiter s 5 m hot spots imply that the equatorial wave inferred to cause hot spots induces vertical parcel oscillation of a factor of 2 in pressure near the 2 bar level which places important constraints on hot spot dynamics finally using spatially resolved radio maps we demonstrate that low latitude features exceeding 4000 km diameter such as the equatorial plumes and large vortices are also depleted in ammonia from 0 6 bars to at least 2 bars relative to the deep abundance of 3 times solar if any low latitude features exist that contain 3 times solar ammonia up to the 0 6 bar ammonia condensation level they must have diameters less than 4000 km

surface mineralogy of martian low albedo regions from mgs tes data implications for upper crustal evolution and surface alteration 1 mars global surveyor thermal emission spectrometer mgs tes data are used to derive the modal mineralogy of spectrally distinct martian low albedo regions and to identify spatial trends in mineralogic assemblages results from this work are consistent with the major results of previous spectroscopic studies 1 plagioclase and clinopyroxene are the dominant minerals of most southern highlands regions 2 the northern plains exhibit the lowest pyroxene abundance within martian low albedo regions and 3 the highest concentrations of high silica phase s are found in the northern plains solis planum and a few southern high latitude regions low albedo regions may be classified into four units on the basis of relative abundances of plagioclase pyroxene and high silica phase s unit distributions between 45 latitude exhibit moderate correlation with distinct provinces e g syrtis major aonium sinus defined by large scale morphology elevation and to some extent surface age suggesting that the spectral and compositional differences between these units are more strongly controlled by original bedrock mineralogy than by surface atmosphere interactions and alteration syrtis major exhibits a difference in mineralogy from the surrounding highlands suggesting a differing degree of fractional crystallization assimilation or source region composition areas with thick crust near the tharsis plateau exhibit lower abundances of olivine and greater plagioclase pyroxene ratios than surrounding highland terrains suggesting that magmas in this region may have undergone increased olivine fractionation regions where surface alteration is more likely to be the primary control on observed spectral signatures are the high latitude areas 45 where globally surfaces dominated by high silica phase s are most commonly found

radio science investigations with mars observer mars observer radio science investigations focus on two major areas of study the gravity field and the atmosphere of mars measurement accuracies expressed as an equivalent spacecraft velocity are expected to be of the order of 100 m s for both types of investigations from use of an improved radio transponder for two way spacecraft tracking and a highly stable on board oscillator for atmospheric occultation measurements planned gravity investigations include a combination of classical and modern elements a spherical harmonic or equivalent field model of degree and order in the range 30 50 will be obtained while interpretation will be in terms of internal stress and density models for the planet using the topography to be obtained from the mars observer laser altimeter atmospheric investigations will emphasize precision measurement of the thermal structure and dynamics in the polar regions which are regularly accessible as a result of the highly inclined orbit studies based on the measurements will include polar processes cycling of the atmosphere between the poles traveling baroclinic disturbances small scale waves and turbulence the planetary boundary layer and possibly the variability and altitude of the ionosphere as the radio occultation is insensitive to dust in the atmosphere per se and measures only the resulting change in thermal structure it is expected that the radio technique can contribute to understanding of dust storm phenomena mutual observations of the atmosphere by means of radio occultation and by the pressure modulator infrared radiometer and the thermal emission spectrometer are expected to strengthen the reliability and accuracy of all three investigations

evidence for amazonian highly viscous lavas in the southern highlands on mars we have identified small scale volcanic edifices two cones and three domes with associated flows within terra sirenum a region situated in the martian southern highlands based on thermal morphological and morphometrical properties and the determination of absolute model ages we conclude that these features were formed by volcanic activity of viscous lavas in the mid amazonian epoch relatively recently in martian history if our hypothesis is correct this small volcanic field represents rare evidence of young volcanic activity in the martian highlands in which martian equivalents of terrestrial lava domes and coulees might be present on earth such landforms are usually formed by highly viscous evolved lavas i e andesitic to rhyolitic for which observational evidence is sparse on mars hence this field might be one of only a few where martian evolved lavas might be investigated in detail