mineralogical characterization of some basaltic asteroids in the neighborhood of 4 vesta first results abstract we present reflectance spectra of 19 v type asteroids obtained at the 3 6 m telescopio nazionale galileo covering 0 8 to 2 5 m for 8 of these asteroids we obtained also visible spectra in the same observational run the range from 0 8 to 2 5 m encompassing the 1 and 2 m pyroxene features allows a precise mineralogical characterization of these asteroids the obtained data suggests the possible coexistence of distinct mineralogical groups among the v type asteroids either probing different layers of 4 vesta or coming from different bodies no clear correlation was found between mineralogies and the objects being or not member of the vesta dynamical family

unsolved problems in plasmasphere refilling the plasmasphere is a cold 1 ev plasma at middle to low magnetic latitudes surrounding the earth its shape is dominated by earth s magnetic field and its cross field motion is dominated by electric fields it is a highly coupled part of the inner magnetosphere storm time conditions erode the outer plasmasphere transporting that plasma into the dayside magnetosheath region leaving behind a region of greatly reduced plasma density that will refill from ionospheric outflow the processes involved in refilling remain incompletely understood in this commentary outstanding questions about plasmaspheric refilling are summarized in the context of recent publications

sounding of the topside ionosphere plasmasphere based on gps measurements from champ initial results 1 beside the gps radio occultation measurements of the troposphere and ionosphere the champ satellite tracks presently up to 8 gps satellites simultaneously for navigation the received dual frequency gps signals provide valuable information on the ionization state of the topside ionosphere and plasmasphere this paper briefly describes a new developed model assisted technique to improve the three dimensional electron density estimation above the champ orbit from these gps measurements application of this assimilation algorithm provides a 2 d electron density slice of the ionosphere plasmasphere system within the champ orbit plane from the champ altitude up to gps orbit heights we estimate the accuracy of the gps tec calibration and perform a first validation by comparing the retrieved electron density of the ionosphere plasmasphere slice at champ altitude to simultaneous electron density measurements of the langmuir probe onboard champ

the correlation between mid latitude trough and the plasmapause 1 we use simultaneous global observations of the mid latitude trough and the plasmapause to experimentally prove a long standing conjecture of magnetosphere ionosphere coupling namely the mid latitude trough and plasmapause are on the same field line global ionospheric maps gim generated using ground based gps receivers are used to detect the globally extended mid latitude trough while global image euv pictures are used to estimate the plasmapause position observations during the equinox and solstices and during quiet and disturbed periods are analyzed in addition positions of the mid latitude trough are calculated using a simple empirical model the two independent observations mid latitude trough and plasmapause positions and an empirical model have been compared on a global scale and found to be in excellent agreement

origin of the basaltic asteroid 1459 magnya a dynamical and mineralogical study of the outer main belt abstract the recent discovery of a relatively small basaltic asteroid in the outer main belt with no apparent link to 4 vesta raised several hypotheses on its origin we present the results of a dynamical and mineralogical study of the region near 1459 magnya intended to establish its origin the dynamical analysis shows that the region is filled with high order two body and three body mean motion resonances and nonlinear secular resonances which can lead to slow chaotic diffusion the mineralogical analysis has not identified any other asteroid with a composition similar to magnya nor the presence of fragments that could be securely related to the catastrophic disruption of a differentiated parent body the various scenarios for the origin of magnya are also discussed in the face of both the results presented here and recently published results

the 3d model of the plasmasphere coupled to the ionosphere pierrard and stegen 2008 has been coupled with the ionospheric iri model in addition to the electron number density the plasmaspheric model is also developed to include the temperature profiles of the different particles and ion composition at altitudes from 60 to 2000 km results of the model for the f region trough are compared with coincident observations of middle and top ionosphere by means of satellite tomography and radar measurements a good match between the model and observations supports the idea that the present model is useful for investigating physical mechanism involved in the plasmasphere ionosphere coupling and for acquiring information about the plasmaspheric behaviour based on ionospheric observations

analysis of tec data from the topex poseidon mission 1 topex poseidon mission has provided an extensive database of vertical tec over the ocean since august 1992 data from nearly 10 years of topex tec observations were analyzed to study the tec climatology first tec data were binned by season geomagnetic activity and solar activity to create longitudinally averaged tec maps in magnetic latitude and local time these maps show the annual and semiannual anomalies well known from climatological studies of nmf2 but lack the seasonal anomaly because of the longitudinally averaged binning the equatorial anomaly is the most prominent feature in the maps and they show strong tec variations with solar activity but relatively weak variations with geomagnetic activity in our three kp bins compared with the low solar activity conditions f10 7 120 the tec values for f10 7 120 are much larger and the equatorial anomaly lasts longer into the night up to midnight during geomagnetically active periods the tec maps generally show a noticeable increase at low latitudes for f10 7 120 but this effect is barely detectable for f10 7 120 finally three longitudinal bins indian pacific and atlantic were added in order to see how the tec morphology varies with longitude the tec measurements display strong longitudinal variations that closely follow the longitudinal variation of the magnetic declination in the southern pacific where the declination is positive and large the diurnal tec variations significantly differ from those in the other longitude sectors where the magnetic declination is negative in the southern hemisphere also at noon the phase of the longitudinal tec variation is typically opposite to that at midnight

the causes of apparent overconsolidation in the namak marine deposit korea an intensive experimental study was carried out to investigate the causes of the overconsolidation phenomena in the namak new city site korea geological events in conjunction with sea level changes groundwater fluctuation weathering leaching and cementation were examined as possible causes of overconsolidation in addition to oedometer and triaxial tests radiocarbon dating geochemical components and pore water chemistry were analysed it was shown that the overconsolidation in the upper marine clay deposit was not caused by stress reductions such as erosion and groundwater fluctuation furthermore weathering or leaching seemed unlikely the apparent overconsolidation can be explained by cementation which is indicated by profiles of the sulphate and potassium ion concentrations in the pore water at the early stage of the holocene marine deposition the rate of deposition was 4 4 mm yr thereafter it was reduced to 1 4 mm yr controlling chemical processes such as sulphate reduction and ion exchan

petrologic insights from the spectra of the unbrecciated eucrites implications for vesta and basaltic asteroids we investigate the relationship between the petrology and visible near infrared spectra of the unbrecciated eucrites and synthetic pyroxene plagioclase mixtures to determine how spectra obtained by the dawn mission could distinguish between several models that have been suggested for the petrogenesis of vesta s crust e g partial melting and magma ocean here we study the spectra of petrologically characterized unbrecciated eucrites to establish spectral observables which can be used to yield mineral abundances and compositions consistent with petrologic observations no information about plagioclase could be extracted from the eucrite spectra in contrast pyroxene dominates the spectra of the eucrites and absorption band modeling provides a good estimate of the relative proportions of low and high ca pyroxene present cr is a compatible element in eucrite pyroxene and is enriched in samples from primitive melts an absorption at 0 6 lm resulting from cr 3 in the pyroxene structure can be used to distinguish these primitive eucrites the spectral differences present among the eucrites may allow dawn to distinguish between the two main competing models proposed for the petrogenesis of vesta magma ocean and partial melting these models predict different crustal structures and scales of heterogeneity which can be observed spectrally the formation of eucrite allan hills alh a81001 which is primitive cr rich and relatively unmetamorphosed is hard to explain in the magma ocean model it could only have been formed as a quench crust if the magma ocean model is correct then alha81001 like material should be abundant on the surface of vesta and the vestoids

experimental study of migration of potassium ion through a two layer soil system a barrier system based on the hydraulic trap design concept for a landfill was proposed to study the field scenario in which a clay liner is underlain by a granular layer functioning as a secondary leachate drain layer a laboratory advection diffusion test was performed to investigate factors controlling the transport of contaminants in a two layer soil system the soils used for this study were ariake clay and the underlying layer shirasu soil from the kyushu region of japan potassium k was selected as the target chemical species with an initial concentration of 905 mg l 1 the effective diffusion coefficients d e of k for ariake clay and shirasu soil were back calculated using an available computer program pollute v 6 3 values of d e derived from this experiment are consistent with previously published ones the ariake clay has lower d e than the shirasu soil the hypothesis that mechanical dispersion can be considered negligible is reasonable based on both the observation that the predicted values well fit the experimental data and the analyses of two dimensionless parameters parametric analyses show that transport of k through soils is controlled by advection diffusion rather than diffusion only whereas at low darcy velocity i e 10 9 m s 1 transport of k will be controlled by diffusion applications of the test results and parametric analysis results in practical situations were reviewed

discovery of a basaltic asteroid in the outer main belt visible and near infrared spectroscopic observations of the asteroid 1459 magnya indicate that it has a basaltic surface magnya is at 3 15 astronomical units au from the sun and has no known dynamical link to any family to any nearby large asteroid or to asteroid 4 vesta at 2 36 au which is the only other known large basaltic asteroid we show that the region of the belt around magnya is densely filled by mean motion resonances generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as magnya magnya may represent a rare surviving fragment from a larger differentiated planetesimal that was disrupted long ago

the m x asteroid menagerie results of an nir spectral survey of 45 main belt asteroids abstract diagnostic mineral absorption features for pyroxene s olivine phyllosilicates and hydroxides have been detected in the near infrared nir approximately 0 75 2 50 m spectra for 60 of the tholen classified tholen 1984 1989 m x asteroids observed in this study nineteen asteroids 42 exhibit weak band i approximately 0 9 m band ii approximately 1 9 m absorptions three asteroids 7 exhibit a weak band i approximately 1 05 1 08 m olivine absorption four asteroids 9 display multiple absorptions suggesting phyllosilicate oxide hydroxide minerals one 1 asteroid exhibits an s asteroid type nir spectrum and 18 asteroids 40 are spectrally featureless in the nir but have widely varying slopes tholen m asteroids are defined as asteroids exhibiting featureless visible wavelength spectra with moderate albedos tholen 1989 tholen x asteroids are also defined using the same spectral criterion but without albedo information previous work has suggested spectral and mineralogical diversity in the m asteroid population rivkin et al 1995 2000 busarev 2002 clark et al 2004 hardersen et al 2005 birlan et al 2007 ockert bell et al 2008 2010 shepard et al 2008 2010 fornasier et al 2010 the pyroxene bearing asteroids are dominated by orthopyroxene with several likely to include higher ca clinopyroxene components potential meteorite analogs include mesosiderites cb ch chondrites and silicate bearing nife meteorites the eos family olivine bearing asteroids are most consistent with a co chondrite analog the aqueously altered asteroids display multiple weak absorptions 0 85 0 92 0 97 1 10 1 40 and 2 30 2 50 m indicative of phyllosilicate hydroxide minerals the spectrally featureless asteroids range from metal rich to metal poor with meteorite analogs including nife meteorites enstatite chondrites and stony iron meteorites

surface lithologic heterogeneity of asteroid 4 vesta abstract high precision spectrophotometry of 4 vesta the third largest asteroid was used to establish the surface composition of this body and to investigate mineralogical variations across its surface the average surface of vesta is analogous to howardite and or polymict eucrite assemblages regolith derived members of the hed meteorite suite which consist of a eucrite matrix containing differing amounts of a diogenite component color and or spectral changes which exhibit a consistent relationship to rotational phasing are evident in 16 of 18 studies of vesta dating back to 1929 including the present work after elimination of possible sources of spurious spectral or color changes it is concluded that these variations arise from hemispheric variations in surface materials and hence provide a means of spatially resolving subhemispheric compositional units on the surface of vesta the background surface of vesta is a relatively dark howardite or polymict eucrite pyroxene plagioclase assemblage with several compositionally distinct bright regions clustered in one hemisphere viewed around the maximum in vesta s lightcurve these include what appears to be an olivine bearing unit suggested name leslie formation located near vesta s equator which probably represents an impact basin and or its associated ejecta that penetrated through the basaltic crust other high albedo compositional units including an apparently low calcium eucrite region and several diogenite pyroxenite regions at least one located near the southern pole may be smaller shallower impact basins by analogy to the eucrite meteorites which represent surface flows or shallow intrusions and which constitute the major component of the regolith derived howardites and polymict eucrites we conclude that the howardite polymict eucrite units represent a regolith gardened original surface of vesta it is probable that the low albedo of the background surface on vesta is due to an age related darkening effect similar to that inferred from the galileo images of gaspra and ida this mechanism is consistent with the correlation of absorption feature intensity with the lightcurve vesta appears to have an old eucritic surface darkened with age and represented among the meteorites by the regolith derived howardites and polymict eucrites on which several impacts on one hemisphere have exposed fresher brighter diogenite and olivine bearing material based on qualitative analysis of the mineralogical variations as a function of rotation a generalized lithologic map of vesta was produced there is reasonable control on the longitude of lithologic features but little control on their latitudes except where specifically noted in producing this map discrete circular features were used on the plausible assumption that impacts have been the most important geologic process on this surface for most of the age of the solar system the shape of the features has thus been assumed rather than derived and is subject to future revision as data improve

mineralogical composition of 25143 itokawa 1998 sf36 from visible and near infrared reflectance spectroscopy evidence for partial melting in march 2001 asteroid 25143 itokawa the target of the japanese hayabusa spacecraft mission was in a favorable viewing geometry for ground based telescopic study visible nearinfrared vnir spectra 0 48 to 0 9 m obtained on march 24 26 and 27 ut and near infrared nir spectra 0 75 to 2 5 m obtained on march 10 11 12 23 and 24 ut collectively show absorption features centered near 1 0 and 2 0 m which are indicative of olivine and pyroxene analyses of these absorption features indicate an abundance ratio of olivine to pyroxene of approximately 75 25 5 respectively with no significant variation in the relative abundance of these minerals across its surface on a regional scale the band center positions indicate that the mean pyroxene chemistry is wo 14 5 fs 43 5 there appear to be at least two pyroxene components primarily a low ca orthopyroxene accompanied by a spectrally significant 15 20 high fe rich pigeonite phase the mean pyroxene composition is significantly more fe rich than the fs1426 range found in ordinary chondrites these pyroxene compositions are suggestive of phases crystallized from partial melts this would indicate that the parent body of 25143 itokawa reached temperatures sufficient to initiate partial melting 1050 to 1250 c but that it did not attain the degree of melting required for significant melt mobilization and efficient segregation of the basaltic melt component from the unmelted residual olivine portion itokawas spectral band parameters place it near the s iii s iv boundary but within the s iii taxonomic field in meteoritic nomenclature itokawa would be most analogous to an olivine rich primitive achondrite alternatively if the high fs value is not related to partial melting then itokawa could also represent a rare atypical ll chondrite or a previously unsampled oxidized fe rich chondritic like assemblage

mineralogy of asteroid 1459 magnya and implications for its origin detailed near infrared spectral observations of asteroid 1459 magnya reveal an asteroid that is primarily composed of pyroxene and plagioclase feldspar confirming earlier suggestions that magnya has a basaltic composition the average magnya spectrum for march 23 2002 has a band i center of 0 926 m and a band ii center of 1 938 m observations over 4 1 hours show little variation in band center positions the feldspar to pyroxene ratio is 0 6 on magnya s surface comparing magnya with the spectral parameters from 4 vesta shows discordant pyroxene chemistries magnya s pyroxenes contain 10 mol less fs than vesta s pyroxenes this suggests that magnya originated from a parent body other than 4 vesta and that its progenitor formed in a more chemically reduced region of the solar nebula within the asteroid belt

siderophile and other geochemical constraints on mixing relationships among hed meteoritic breccias we have used neutron activation and electron probe fused bead techniques to analyze the bulk major and trace element compositions of 104 named hed meteorites about 100 102 distinct meteorites depending upon pairings including 32 polymict eucrites 30 howardites and six diogenites most were not previously analyzed for siderophile trace elements many not even for major elements our typical sample was 350 mg and in some cases two separate chips were analyzed as a test of meteorite heterogeneity meteorites with extraordinary compositions include bluewing 001 an unequilibrated eucrite that is rich in ti sm and other incompatible elements y 791192 a cumulate dominated polymict eucrite and lew 87002 an oddly sm rich howardite dominated by a ferroan variety of diogenite the eucrite diogenite mixing ratio is the single most important factor determining the compositions of polymict heds but wide ranges in eucrite incompatible element contents in diogenite cr and v contents and in sc contents of both eucrites and diogenites make for diversity among the polymict heds as our new siderophile data help to show the common practice of describing the entire class of howardites as regolith breccias is erroneous most howardites are fragmental breccias showing no sign of origin from true in the lunar sense i e soil like near surface regolith howardites are highly diverse in ni content often remarkably ni poor compared to lunar regolith breccias however the few 8 howardites with between 300 and 1200 lg g ni consistently show some combination of other traits suggestive of regolith origin most importantly all four cases or five if we include malvern which appears to have been altered by annealing of howardites known to have enrichments in solar wind noble gases belong to the 300 lg g ni group in many cases an abundance of glasses particularly in spheroidal or turbid brown form provides additional evidence for regolith origin we propose that the important subset of howardites that are regolith breccias be formally distinguished by the designation regolithic howardite apart from high siderophile levels the regolithic howardites are compositionally distinctive in having al2o3 consistently near 8 9 wt corresponding to a eucrite diogenite mixing ratio of precisely 2 1 assuming the heds are reasonably representative of the ancient i e pre vestoid launch surface of vesta this clustering of regolith composition is difficult to explain unless most of the ancient diogenite component was brought to the surface in a single early episode i e probably a single great impact after which smaller scale cratering with no further major excavations of diogenite until the vestoid forming event efficiently homogenized the surface such a single excavation model may also help to explain why diogenites in marked contrast with eucrites are seldom polymict and why al2o3 poor diogenite dominated howardites consistently lack major siderophile enrichments the low siderophile contents of polymict eucrites are most enigmatic possibly in the hedasteroidal context low collision velocities etc only materials blended by multiple impacts consistently acquire major enrichments in siderophile elements 2009 elsevier ltd all rights reserved

impact excavation on asteroid 4 vesta hubble space telescope results hubble space telescope images of asteroid 4 vesta obtained during the favorable 1996 apparition show an impact crater 460 kilometers in diameter near the south pole color measurements within the 13 kilometer deep crater are consistent with excavation deep into a high calcium pyroxene rich crust or olivine upper mantle about 1 percent of vesta was excavated by the crater formation event a volume sufficient to account for the family of small vesta like asteroids that extends to dynamical source regions for meteorites this crater may be the site of origin for the howardite eucrite and diogenite classes of basaltic achondrite meteorites

pyroxene spectroscopy revisited spectral compositional correlations and relationship to geothermometry the authors wish to thank the various agencies which have provided the necessary support for this project including grants in aid of research from sigma xi the scientific research society to e a c the geological society of america grant 3741 87 to e a c and nasa planetary geology and geophysics grant nagw 642 to m j g

depositional and post depositional geochemistry and its correlation with the geotechnical properties of marine clays in ariake bay japan the mineralogy geochemistry and geotechnical properties of clay samples in ariake bay japan are presented the mineralogy and geochemistry are discussed in terms of depositional and post depositional processes and the correlations of the clay mineralogy and geochemistry with the geotechnical properties were examined by multiple regression analysis the most predominant clay mineral in the deposits was found to be smectite the vertical distribution of trace elements in the deposits was indicative of the periodical changes in the parent materials involved in the depositional processes the chloride concentration in the pore water varied according to a change in the sea level from brackish to marine and then brackish towards the surface the higher iron oxide contents near the surface and in the deepest zones were the results of pyrite oxidation in the deposits due to weathering under subaerial conditions smectite content was the most predominant governing factor for the consistency limits and activi

oxygen and asteroids hundreds of thousands of asteroids have been discovered in the asteroid belt and in near earth space oxygen is an abundant element in meteorites and presumably in most asteroids spectral reflectance measurements of asteroids in the visible and near infrared can identify oxygen bearing minerals such as those found in the olivine pyroxene and serpentine groups due to their distinctive absorption features interpretation of the mineralogy of asteroids is complicated by the effects of space weathering which tends to redden and darken the surfaces of asteroids asteroids are primarily classified into a number of taxonomic classes and subclasses according to their spectral properties in the visible wavelength region however asteroids with similar spectral properties in the visible may have different spectral properties in the near infrared and therefore different interpreted mineralogies definite trends in the abundances of different taxonomic classes versus heliocentric distance are apparent these trends appear to be a function of both composition differences and degree of heating however dynamical processes have significantly affected these trends close observation of asteroids by spacecraft such as near shoemaker to 433 eros and hayabusa to 25143 itokawa are currently the best way to discern the mineralogies of individual asteroids

experimental study on the deterioration and natural remediation of the ariake sea tidal mud caused by the sea laver treatment acid practice and the upward seepage of pore water liquid this study presents a laboratory study of the following two aspects 1 the influence of sea laver treatment acid on the geoenvironmental properties of ariake sea tidal mud and 2 the natural remediation effect on the sea laver treatment acid contaminated ariake sea tidal mud caused by the upward seepage of pore water liquid in the mud firstly the mechanisms of the transport of sea laver treatment acid in the ariake sea tidal mud and the generation mechanisms of the upward seepage flow in the ariake sea tidal mud are discussed secondly a series of one dimensional laboratory infiltration tests were carried out to investigate the deterioration of the ariake sea tidal mud caused by the sea laver acid treatment practice test results reveal that the acid treatment practice caused considerable change in the geochemical properties of the mud in terms of increase in sulfide content and decrease in ph value after the treatment by the sea laver treatment acid the sulfide content of the mud even exceeded the safe limit value for the benthos which represents undesirable living condition for benthos thirdly series of laboratory fresh seawater infiltration tests for the deteriorated iida site mud were conducted to illustrate this natural remediation efficiency it is found that with the infiltration of the fresh seawater the sulfide content of the iida site mud was considerably reduced and ph value increased to an acceptable range for benthos living in the tidal flat mud with the increase in the infiltration time and the hydraulic gradient the remediation efficiency could be increased

vesta and the vestoids a new rock group abstract moderate spectral resolution observations of the 505 nm fe2 pyroxene absorption feature were obtained for 13 asteroids dynamically linked to 4 vesta or located between vesta and the 3 1 resonance gap eleven showed spectra with deep 0 9 m mafic silicate absorptions suggesting a pyroxene composition binzel and xu 1993 spectra of only six of these asteroids show the absorption feature centered at 506 5 nm suggestive of an augite high calcium component to the surface pyroxenes consistent with previous spectral observations across the surface of vesta cochran and vilas 1998 five of the six asteroids include all objects observed at heliocentric distances between vesta and the 3 1 resonance gap the spectrum of only one asteroid interior to vesta s orbit showed this feature no correlation between the presence or absence of this feature and the strength of the 1 m mafic silicate feature was found

the altitude extension of the mid latitude trough and its correlation with plasmapause position 1 tomographic imaging provides a powerful technique for obtaining images of the spatial distribution of ionospheric electron density in an altitude versus geographic latitude grid at a specified longitudinal sector the method which involves monitoring the total electron content tec of the ionosphere using signals transmitted from the global positioning system gps has the ability to reveal the detailed structure of the ionosphere including the mid latitude trough the tomographic reconstruction of ionospheric electron density structures are performed at different specific longitudinal sectors both in the northern and southern hemisphere at the same time the plasmapause position is estimated from image euv images and mapped onto tomographic images the simultaneous location of the altitude extension of the mid latitude trough and the plasmapause position are essentially co located

motion and erosion of the nightside plasmapause region and of the associated subauroral electron temperature enhancement cosmos 900 observations ion densities n i and electron temperatures t e measured on board cosmos 900 satellite launched at march 30 1977 into near polar circular orbit i 83 h 500 km orbital period 94 min are used to study the behavior of the ionosphere during the prestorm initial and main phases of the magnetic storm of december 1 2 1977 the spatial resolution of the measurement was 0 3 latitude for t e and 0 1 latitude for n i during this period 27 orbits were recorded in the onboard large storage memory this enabled detailed study of the positions and latitude profiles of midlatitude ionospheric trough and subauroral electron temperature enhancement sete in the midnight local time sector simultaneous proton density data measured on the high altitude satellites prognoz 5 and prognoz 6 confirm that the poleward boundary of the t e peak corresponds to the ionospheric magnetic field projection of the high altitude plasmapause density knee during the main phase of a geomagnetic storm the polar edge of the sete becomes very steep it coincides with an equally steep poleward edge of the midlatitude ionospheric trough and with the position of the newly forming density gradient of the high altitude plasmapause the sequence of cosmos 900 observations clearly shows how the nighttime midlatitude ionospheric trough fills up as well as how the subauroral electron temperature enhancement and the outer layers of the plasmasphere are eroded during a geomagnetic storm these results shed new light on the formation of the plasmapause in the postmidnight sector and on the time dependent electric field distribution in the nightside sector before and during a geomagnetic storm

mlt plasmapause characteristics comparison between themis observations and numerical simulations we perform a statistical comparison of the global behavior of the themis observed and simulated plasmapause in the geomagnetic equatorial plane simulation is based on the interchange instability mechanism analyzing plasmapause positions lpps from the period july 2008 to december 2012 we derived formation and propagation characteristics of the main plasmapause which reflect the most probable global plasmapause behavior the results suggest a global eastward azimuthal plasmapause propagation and a radial plasmapause motion limited to the 21 07 mlt sector the formation of the plasmapause takes place with the highest probability at postmidnight it is likely that the erosion occurs in a range of mlts simultaneously on the dayside the plasmapause moves almost entirely azimuthally we suggest that the plasmapause propagates azimuthally with a mean angular velocity close to the corotation speed at all mlts at least during periods of lower geomagnetic activity the results also show that the experimental plasmapause characteristics are in accordance with the interchange instability mechanism along with the proposed suggestions for future works this study contributes to making a further step toward resolving some of the long lasting unresolved issues related to plasmapause dynamics

distinct control mechanism of fine grained sediments from yellow river and kyushu supply in the northern okinawa trough since the last glacial high resolution multi proxy records including clay minerals and sr nd pb isotopes of the clay sized silicate fraction of sediments from iodp site u1429 in the northern okinawa trough provide reliable evidence for distinct control mechanism on fine grained sediments input from the yellow river and the southern japanese islands to the northern okinawa trough since 34 ka bp provenance analysis indicates that the sediments were mainly derived from the yellow river and the island of kyushu since the last glacial clay sized sediments transported from the yellow river to the study site were strongly influenced by sea level fluctuation during low sea level stage 34 14 ka bp the paleo yellow river mouth was positioned closer to the northern okinawa trough favoring large fluvial discharge or even direct input of detrital sediments which resulted about four times more flux of clay sized sediments supply to the study area as during the relatively high sea level stage 14 0 ka bp the input of kyushu derived clay sized sediments to the study site was mainly controlled by the kuroshio current and tsushima warm current intensity with increased input in phase with weakened kuroshio current tsushima warm current our study suggests that the kuroshio current was very likely flowed into the okinawa trough and thus influenced the fine grained sediment transport in the area throughout the last glacial and deglacial during 34 11 ka bp the kyushu clay sized sediment input was mainly controlled by the kuroshio current since 11 ka bp the occurrence of tsushima warm current became important in influencing the kyushu fine grained sediment input to the northern okinawa trough

quaternary sedimentary record in the northern okinawa trough indicates the tectonic control on depositional environment change abstract during the quaternary global sea level was characterized by large fluctuations in amplitude and increased frequency however the eastern marginal seas of china especially the northern east china sea and yellow sea did not experience large scale transgression until the middle pleistocene the zhe min zhejiang fujian uplift was an important barrier in the east china sea preventing transgression of sea water into the northern marginal seas of china but its quaternary evolution is still poorly constrained here we present a thick sand layer record the top age is 416 ka of the integrated ocean drilling program iodp site u1428 from the northern okinawa trough to reconstruct the history of the zhe min uplift since the middle pleistocene provenance analysis indicates that sediments from both sand and imbedded fine grained calcareous rich clay layers at the study site were mainly derived from the yellow river which for the first time indicates that the yellow river sediments could influence the northern okinawa trough since at least the middle pleistocene significant change of lithology at iodp site u1428 at 416 ka was attributed to the large scale subsidence of the zhe min uplift which is probably due to the rapid uplifting of tibet during 0 52 0 38 ma before 416 ka obstacle of the emersed zhe min uplift induced extremely severe reworking and promoted sand ridge formation in the shelf edge of southeastern yellow sea and supplied sand sediments to the northern okinawa trough during transgression and high sea level stages after the subsidence of the zhe min uplift at 416 ka westward of tidal sand ridge and yellow river mouth with the process of shelf transgressions favored fine grained sediments input to the northern okinawa trough even during low sea level stages the flat terrain of the east asian marginal sea shelf and low rainfall amount resulted in low discharge of yellow river and supplied fine grained particles to the northern okinawa trough

new model fit functions of the plasmapause location determined using themis observations during the ascending phase of solar cycle 24 it is well known that the plasmapause is influenced by the solar wind and magnetospheric conditions empirical models of its location have been previously developed such as those by o brien and moldwin 2003 and larsen et al 2006 in this study we identified the locations of the plasmapause using the plasma density data obtained from the time history of events and macroscale interactions during substorms themis satellites we used the data for the period 2008 2012 corresponding to the ascending phase of solar cycle 24 our database includes data from over a year of unusually weak solar wind conditions correspondingly covering the plasmapause locations in a wider l range than those in previous studies it also contains many coronal hole stream intervals during which the plasmasphere is eroded and recovers over a timescale of several days the plasmapause was rigorously determined by requiring a density gradient by a factor of 15 within a radial distance of 0 5 l we first determined the statistical correlation of the plasmapause locations with several solar wind parameters as well as geomagnetic indices we found that the plasmapause locations are well correlated with the solar wind speed and the interplanetary magnetic field bz therefore the y component of the convective electric field and some energy coupling functions such as the well known akasofu s epsilon parameter the plasmapause locations are also highly correlated with the geomagnetic indices dst ae and kp as recognized previously finally we suggest new model fit functions for the plasmapause locations in terms of the solar wind parameters and geomagnetic indices when applied to a new data interval outside the model training interval our model fit functions work better than existing ones the new model fit functions developed here extend the range of conditions from those used in previous works

spectral properties of angrites angrites are generally believed to be fragments of a basaltic asteroid that differentiated under relatively oxidizing conditions almost all angrites e g d orbigny lewis cliff lew 86010 and sahara 99555 are composed predominately of anorthite al ti diopside hedenbergite and ca rich olivine except for the type specimen angra dos reis which is composed almost entirely of al ti diopside hedenbergite d orbigny lew 86010 and sahara 99555 also have spectral properties very different from angra dos reis these newly measured angrites all have broad absorption features centered near 1 m with very weak to absent absorption bands at 2 m which is characteristic of some clinopyroxenes the spectrum of angra dos reis has the characteristic 1 and 2 m features due to pyroxene one asteroid 3819 robinson has similar spectral properties to the newly measured angrites in the visible wavelength region but does not appear to spectrally match these angrites in the near infrared

a microstructural investigation of osaka bay clay the impact of microfossils on its mechanical behaviour a recent microstructural investigation of osaka bay clay sediments has revealed the presence of abundant microfossils particularly in the marine layers which appear to influence directly the micr

the distribution of basaltic asteroids in the main belt abstract we present the observational results of a survey designed to target and detect asteroids whose photometric colors are similar to those of vesta family members and thus may be considered as candidates for having a basaltic composition fifty basaltic candidates were selected with orbital elements that lie outside of the vesta dynamical family optical and near infrared spectra were used to assign a taxonomic type to 11 of the 50 candidates ten of these were spectroscopically confirmed as v type asteroids suggesting that most of the candidates are basaltic and can be used to constrain the distribution of basaltic material in the main belt using our catalog of v type candidates and the success rate of the survey we calculate unbiased size frequency and semi major axis distributions of v type asteroids these distributions in addition to an estimate for the total mass of basaltic material suggest that vesta was the predominant contributor to the basaltic asteroid inventory of the main belt however scattered planetesimals from the inner solar system a 2 0 au and other partially fully differentiated bodies likely contributed to this inventory in particular we infer the presence of basaltic fragments in the vicinity of asteroid 15 eunomia which may be derived from a differentiated parent body in the middle main belt 2 5 a 2 8 we find no asteroidal evidence for a large number of previously undiscovered basaltic asteroids which agrees with previous theories suggesting that basaltic fragments from the 100 differentiated parent bodies represented in meteorite collections have been battered to bits burbine t h meibom a binzel r p 1996 meteorit planet sci 31 607 620

gaussian analysis of temperature effects on the reflectance spectra of mafic minerals in the 1 μm region gaussian band fitting analysis has been applied to the reflectance spectra of mafic silicates which are of geologic importance throughout much of the solar system reflectance spectra obtained over a sample temperature range of 80 to 448 k of olivine clinopyroxene and orthopyroxene were used in order to characterize the spectral changes in the 1 m wavelength region of these minerals as a function of temperature four gaussians are required to characterize the olivine while two gaussians are necessary to characterize both the orthopyroxene and clinopyroxene the trends of the individual gaussian parameters integrated area width and center position are presented as a function of temperature for each mineral the characterization by gaussian analysis of the 1 m absorption feature of all minerals yields consistent trends in center position integrated area and width that may prove useful in quantitative determination of these minerals in mineral mixtures the gaussian analysis of olivine for the three primary band components is qualitatively consistent with previous crystal field transition assignments of fe2 in the m 1 and m 2 crystallographic sites the trends of the determined olivine gaussian center positions imply that site symmetry is more important in determining transition energies than metal oxygen distances the result of the gaussian analysis for orthopyroxene is consistent with the need for two gaussians to describe an asymmetric band the gaussian analysis of the clinopyroxene is consistent with previous assignments of crystal field transitions due to fe2 in the m 1 and m 2 crystallographic sites

dawn the vesta hed connection and the geologic context for eucrites diogenites and howardites the dawn mission has provided new evidence strengthening the identification of asteroid vesta as the parent body of the howardite eucrite and diogenite hed meteorites the evidence includes vesta s petrologic complexity detailed spectroscopic characteristics unique space weathering diagnostic geochemical abundances and neutron absorption characteristics chronology of surface units and impact history occurrence of exogenous carbonaceous chondritic materials in the regolith and dimensions of the core all of which are consistent with hed observations and constraints global mapping of the distributions of hed lithologies by dawn cameras and spectrometers provides the missing geologic context for these meteorites thereby allowing tests of petrogenetic models and increasing their scientific value

pyroxene mineralogies of near earth vestoids we have calculated pyroxene mineralogies of seven near earth asteroids neas with reflectance spectra similar to heds howardites eucrites and diogenites two different sets of formulas gaffey et al 2002 burbine et al 2007 are used to calculate the pyroxene mineralogies of the neas from their band i and ii centers the band centers have been adjusted to compensate for the low temperatures on the asteroid surfaces all of the derived mineralogies from the gaffey et al 2002 formulas and the burbine et al 2007 formulas overlap the derived wollastonite wo contents are very similar with differences being only approximately 1 mol the derived ferrosilite fs contents differ by only 3 to 8 mol the determined pyroxene mineralogies for all seven near earth vestoids are consistent with eucrites or howardites none of the objects have pyroxene mineralogies consistent with diogenites the absence of near earth vestoids with pyroxene mineralogies similar to diogenites may indicate that it is difficult to produce sizeable km sized or larger bodies that are predominantly composed of diogenitic material suggesting these objects are rubble piles of mixed ejecta

postmidnight ionospheric troughs in summer at high latitudes in this article we identify possible mechanisms for the formation of post midnignt ionospheric troughs during summer in sunlit plasma four events were identified in measurements of eiscat and esr radars during cp3 experiments when the ionosphere was scanned in a meridional plan the spatial and temporal variation of plasma density ion and electron temperatures were analysed for each of the four events superdarn plasma velocity measurements were added when these were available for all high latitude troughs the ion temperatures are high at density minima within the trough at places where the convection plasma velocity is eastward and high there is no significant change in electron temperature inside the trough regardless of its temporal evolution we find that troughs in sunlit plasma form in two steps the trough starts to form when energetic electron precipitation leads to faster recombination in the f region and it deepens when entering a region with high eastward flow producing frictional heating and further depleting the plasma the high latitude plasma convection plays an important role in formation and evolution of troughs in the post midnight sector in sunlit plasma during one event a second trough is identified at mid latitudes with different characteristics which is most likely produced by a rapid sub auroral ion drift said in the premidnight sector

a new source of basaltic meteorites inferred from northwest africa 011 eucrites are a class of basaltic meteorites that share common mineralogical isotopic and chemical properties and are thought to have been derived from the same parent body possibly asteroid 4 vesta the texture mineralogy and noble gas data of the recently recovered meteorite northwest africa nwa 011 are similar to those of basaltic eucrites however the oxygen isotopic composition of nwa011 is different from that of other eucrites indicating that nwa011 may be derived from a different parent body the presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies perhaps similar to 4 vesta in the early solar system

transformations and correlations among some clay parameters the global database this study compiles a large database of 10 clay parameters labeled as clay 10 7490 from 251 studies covering clay data from 30 regions or countries worldwide hence the range of data covered by

depositional and geotechnical properties of marine clays in lianyungang china the mineralogy geochemistry and geotechnical properties of clay samples in lianyungang china are presented the correlations of depositional history depositional environmental and geotechnical properties are discussed a series of x ray diffraction tests show that the principal clay minerals of the soil are illite smectite mixed layer mineral and illite the geochemistry investigation results indicate that the pore water of the lianyungang marine clay is dominant by sodium the ph of the soils varies in the range of 7 8 to 8 9 the depositional environment is oxidation condition the correlations of the geochemistry with the geotechnical properties are examined by the statistic analysis

a semiempirical equatorial mapping of amie convection electric potentials macep for the january 10 1997 magnetic storm owing to satellite and instrumental limitations in situ magnetospheric electric field measurements are only available at isolated locations during storm time conditions a global view of the inner magnetospheric convection electric field can be obtained by mapping ionospheric potentials into the equatorial plane a mapping procedure for assimilative mapping of ionospheric electrodynamics amie ionospheric potentials macep is used to obtain convection patterns for the january 10 1997 magnetic storm the results are compared with the widely used empirical volland stern model and the mapping of weimer ionospheric potentials while the gross temporal evolution of the large scale potential drop across the magnetosphere is similar in all three models detailed intercomparison shows that the macep procedure is capable of resolving highly variable and relatively small scale features of the electric field that are not treated by the volland stern model nor seen from the weimer mapping the macep results are in reasonable agreement with limited electric field measurements from the electric field instrument on the polar spacecraft and lanl measurements of thermal ion velocities at geosynchronous orbit during prestorm and recovery phase conditions however the inner boundary condition employed in the current version of amie is unable to reproduce the magnitude of the penetrating electric fields observed in the inner magnetosphere during the main phase of a storm the addition of a penetration electric field associated with an asymmetric ring current in the dusk sector improved macep results at the duskside low l region

long lived plasmaspheric drainage plumes where does the plasma come from long lived weeks plasmaspheric drainage plumes are explored the long lived plumes occur during long lived high speed stream driven storms spacecraft in geosynchronous orbit see the plumes as dense plasmaspheric plasma advecting sunward toward the dayside magnetopause the older plumes have the same densities and local time widths as younger plumes and like younger plumes they are lumpy in density and they reside in a spatial gap in the electron plasma sheet in sort of a drainage corridor magnetospheric convection simulations indicate that drainage from a filled outer plasmasphere can only supply a plume for 1 5 2 days the question arises for long lived plumes and for any plume older than about 2 days where is the plasma coming from three candidate sources appear promising 1 substorm disruption of the nightside plasmasphere which may transport plasmaspheric plasma outward onto open drift orbits 2 radial transport of plasmaspheric plasma in velocity shear driven instabilities near the duskside plasmapause and 3 an anomalously high upflux of cold ionospheric protons from the tongue of ionization in the dayside ionosphere which may directly supply ionospheric plasma into the plume in the first two cases the plume is drainage of plasma from the magnetosphere in the third case it is not where the plasma in long lived plumes is coming from is a quandary to fix this dilemma further work and probably full scale simulations are needed

longitudinal differences of ionospheric vertical density distribution and equatorial electrodynamics 1 accurate estimation of global vertical distribution of ionospheric and plasmaspheric density as a function of local time season and magnetic activity is required to improve the operation of space based navigation and communication systems the vertical density distribution especially at low and equatorial latitudes is governed by the equatorial electrodynamics that produces a vertical driving force the vertical structure of the equatorial density distribution can be observed by using tomographic reconstruction techniques on ground based global positioning system gps total electron content tec similarly the vertical drift which is one of the driving mechanisms that govern equatorial electrodynamics and strongly affect the structure and dynamics of the ionosphere in the low midlatitude region can be estimated using ground magnetometer observations we present tomographically reconstructed density distribution and the corresponding vertical drifts at two different longitudes the east african and west south american sectors chains of gps stations in the east african and west south american longitudinal sectors covering the equatorial anomaly region of meridian 37 e and 290 e respectively are used to reconstruct the vertical density distribution similarly magnetometer sites of african meridian b field education and research amber and intermagnet for the east african sector and south american meridional b field array samba and low latitude ionospheric sensor network lisn are used to estimate the vertical drift velocity at two distinct longitudes the comparison between the reconstructed and jicamarca incoherent scatter radar isr measured density profiles shows excellent agreement demonstrating the usefulness of tomographic reconstruction technique in providing the vertical density distribution at different longitudes similarly the comparison between magnetometer estimated vertical drift and other independent drift observation such as from vefi onboard communication navigation outage forecasting system c nofs satellite and julia radar is equally promising the observations at different longitudes suggest that the vertical drift velocities and the vertical density distribution have significant longitudinal differences especially the equatorial anomaly peaks expand to higher latitudes more in american sector than the african sector indicating that the vertical drift in the american sector is stronger than the african sector

influence of the convection electric field models on predicted plasmapause positions during magnetic storms in the present work we determine how three well documented models of the magnetospheric electric field and two different mechanisms proposed for the formation of the plasmapause influence the radial distance the shape and the evolution of the plasmapause during the geomagnetic storms of 28 october 2001 and of 17 april 2002 the convection electric field models considered are mcilwain s e5d electric field model volland stern s model and weimer s statistical model compiled from low earth orbit satellite data the mechanisms for the formation of the plasmapause to be tested are 1 the mhd theory where the plasmapause should correspond to the last closed equipotential lce or last closed streamline lcs if the e field distribution is stationary or timedependent respectively 2 the interchange mechanism where the plasmapause corresponds to streamlines tangent to a zero parallel force surface where the field aligned plasma distribution becomes convectively unstable during enhancements of the e field intensity in the nightside local time sector the results of the different time dependent simulations are compared with concomitant euv image observations when available the plasmatails or plumes observed after both selected geomagnetic storms are predicted in all simulations and for all e field models however their shapes are quite different depending on the e field models and the mechanisms that are used despite the partial success of the simulations to reproduce plumes during magnetic storms and substorms there remains a long way to go before the detailed structures observed in the euv observations during periods of geomagnetic activity can be accounted for very precisely by the existing e field models furthermore it cannot be excluded that the mechanisms currently identified to explain the formation of carpenter s knee during substorm events will have to be revised or complemented in the cases of geomagnetic storms

the antarctic achondrite alha 76005 a polymict eucrite abstract alha 76005 is a basaltic achondrite containing few if any orthopyroxenes its bulk major and trace element composition is like that of a non cumulate eucrite and unlike that of a howardite it contains a variety of igneous clasts which differ in their textures pyroxene plagioclase ratios and pyroxene and plagioclase compositions one clast no 4 was found to have the ree pattern of a cumulate eucrite and an oxygen isotopic composition different from that of the bulk meteorite both the chemical and oxygen isotopic composition of clast no 4 suggest that it was derived from a source different from its host these observations lead to the conclusion that alha 76005 is a polymict eucrite

geologic mapping of vesta from 1994 hubble space telescope images we utilize the 56 images of asteroid 4 vesta obtained through four mineralogically diagnostic filters by the hubble space telescope zellneret al 1997 icarus to construct a geologic map vesta s surface is found to be geologically diverse and to be dichotomous at a hemispheric scale the eastern hemisphere longitude definition from thomaset al 1997 icarus is dominated by units interpreted to be impact excavated plutonic material composed of magnesium rich and calcium poor pyroxene the mineralogy of this region is most analogous to diogenite meteorites several eastern hemisphere units which have the deepest and broadest 1 m absorption bands may contain a substantial olivine component the locations of these units are consistent with a previous map based on rotationally resolved groundbased spectroscopy gaffey 1997 icarus the western hemisphere is dominated by units interpreted to consist of a single component of iron rich and relatively calcium rich pyroxene analogous to surface basalts such as eucrite meteorites we investigate the spectral properties of 20 representative surface regions and find a correlation between the 1 m absorption band depth and albedo the units with lower albedos have shallower band depths such a relation could arise from differences in lithologies differences in surface particle sizes or from a weathering effect which decreases albedo and band depth over time because of vesta s geologic diversity and hemispheric dichotomy it is apparent that any major impact events such as those possibly related to the formation of the vesta family binzel and xu 1993 science260 186 191 did not globally resurface the planet the spectral evidence for remnants of a basaltic crust implies that the oldest units on the surface date back to the time of their emplacement most likely 4 5 byr ago if a weathering process exists which alters the albedo then the lowest albedo units such as the feature with the proposed name olbers most likely represent remnants of vesta s ancient basaltic crust

revisiting spectral parameters of silicate bearing meteorites visible and near infrared reflectance spectra of a sample of silicate bearing meteorites have been used to evaluate the spectral parameters space defined in the pioneering work of gaffey et al 1993 the studied sample consisted of 91 ordinary chondrites 47 basaltic achondrites and 21 different laboratory mixtures obtained from the relab database our results indicate that the spectral parameter space in particular the bar versus band i center is not suitable enough to identify the mineralogy of meteorites and asteroids the grain size of the sample also appears as a very sensitive parameter and can play an important role in locating an object in the spectral parameter space finally the application of our study to the question of a genetic link between v type asteroids and hed meteorites shows that these bodies plot in distinct regions in the bar versus band i center space this result further confirms that those spectral parameters cannot uniquely define the mineralogy of a sample

high calcium pyroxene as an indicator of igneous differentiation in asteroids and meteorites our analyses of high quality spectra of several s type asteroids 17 thetis 847 agnia 808 merxia and members of the agnia and merxia families reveal that they include both low and highcalcium pyroxene with minor amounts of olivine 0 4 high calcium pyroxene is a spectrally detectable and petrologically important indicator of igneous history and may prove critical in future studies aimed at understanding the history of asteroidal bodies the silicate mineralogy inferred for thetis and the merxia and agnia family members requires that these asteroids experienced igneous differentiation producing broadly basaltic surface lithologies together with 4 vesta and its smaller vestoid family members and the main belt asteroid 1489 magnya these new asteroids provide strong evidence for igneous differentiation of at least five asteroid parent bodies based on this analysis of a small subset of the near infrared asteroid spectra taken to date with spex at the nasa irtf we expect that the number of known differentiated asteroids will increase consistent with the large number of parent bodies inferred from studies of iron meteorites

plasmapause undulation of 17 april 2002 1 we report image euv observations of a striking undulatory motion of the plasmapause that occurred on 17 april 2002 in which a large ripple propagated westward across the duskside plasmapause from the plasmapause motion we infer a peak e field of 3 mv m associated with the undulation and estimate the undulation s equatorial azimuthal speed to be 0 9 rad hr 4 re hr corresponding to 1 km s in the ionosphere using an r3 2 dependence to map from the equator because dmsp ion drift data at 850 km altitude show the presence of a subauroral polarization stream saps flow channel 1 km s at the same location and time as the undulation we assert that saps was responsible for removal of plasma during the undulation the saps apparently formed in response to a 19 00 ut substorm onset

global response of the plasmasphere to a geomagnetic disturbance 1 global images of the plasmasphere obtained by the extreme ultraviolet euv imager on the image satellite are used to study the evolving structure of the plasmasphere during two geomagnetic disturbances by tracking the location of the plasmapause as a function of l shell and magnetic local time quantitative measurements of radial and azimuthal motions of the boundary are made for intervals 7 hours in duration with a time resolution of 10 min the two cases presented are 26 27 june 2001 a relatively weak but isolated geomagnetic disturbance and 9 10 june 2001 a moderate event with a multistaged onset and recurring substorm activity after the main disturbance in both cases the onset of the disturbance correlated with a southward turning of the imf is characterized by inward motion or erosion of the plasmapause and a smoothing of any existing azimuthal variations across the nightside over a period of many hours a plasmaspheric plume forms in the afternoon sector as a result of sunward flows from dusk and corotational flows across the dayside azimuthal variations in the plasmapause radius tend to form in the local time sector from dawn to the western edge of the plume including mesoscale 0 5 in l and 2 hours in local time crenulations and larger scale shoulder features while the nightside boundary remains featureless in the 26 27 june 2001 case the magnetosphere entered a period of deep quiet after the main disturbance and the plasmaspheric plume began to corotate with the main plasmasphere from the afternoon sector across the nightside in contrast the plume in the 9 10 june 2001 event became wrapped around the main plasmasphere and a second plume formed in the afternoon sector perhaps due to continued substorm activity in situ density data for these events show highly irregular density structure within the plumes as measured at geosynchronous orbit whereas a measurement by image rpi suggests that there may be less structure near the base of the plume closer to the main plasmasphere

the compositional diversity of non vesta basaltic asteroids abstract we present near infrared 0 78 2 45 m reflectance spectra for nine middle and outer main belt a 2 5 au basaltic asteroids three of these objects are spectrally distinct from all classifications in the bus demeo system and could represent spectral end members in the existing taxonomy or be representatives of a new spectral type the remainder of the sample are classified as v or r type all of these asteroids are dynamically detached from the vesta collisional family but are too small to be intact differentiated parent bodies implying that they originated from differentiated planetesimals which have since been destroyed or ejected from the solar system the 1 and 2 m band centers of all objects determined using the modified gaussian model mgm were compared to those of 47 vestoids and fifteen hed meteorites of known composition the heds enabled us to determine formulas relating band 1 and band 2 centers to pyroxene ferrosilite fs compositions using these formulas we present the most comprehensive compositional analysis to date of middle and outer belt basaltic asteroids we also conduct a careful error analysis of the mgm derived band centers for implementation in future analyses the six outer belt v and r type asteroids show more dispersion in parameter space than the vestoids reflecting greater compositional diversity than vesta and its associated bodies the objects analyzed have fs numbers which are on average between five and ten molar percent lower than those of the vestoids however identification and compositional analysis of additional outer belt basaltic asteroids would help to confirm or refute this result given the gradient in oxidation state which existed within the solar nebula these results tentatively suggest that these objects formed at either a different time or location than 4 vesta

effect of quaternary transgression and regression on the engineering properties of shanghai soft clays abstract the engineering properties of marine clays are closely related to its depositional environment however the correlation between the chemical properties and depositional environment and their effect on engineering properties of upper shanghai marine clay are still pending the sedimentary processes of upper shanghai marine clays from the quaternary transgression the correlation between the chemical properties and its depositional history are investigated in this study based on a series of laboratory experiments the distribution of chemical indicators e g ph value oxidation reduction potential and salt content with depth showed that the depositional environment directly affected the chemical properties of the soil layer the correlation of salt content with sensitivity liquid limit and liquidity index in upper shanghai layers represents a unique two stage distribution with the boundary at the bottom of the layer 4 clay the two stage distribution is caused by the quaternary transgression and regression which is confirmed to have different effects on the salt content sensitivity liquid limit and liquidity index the quantitative approaches used to evaluate the correlation between depositional environment chemical and mechanical properties can provide valuable references for investigating the engineering properties of soft clays

fugitives from the vesta family abstract spectroscopic observations of asteroid 4 vesta and numerous members of the vesta family located in the inner asteroid belt have determined that these objects have reflectance properties of basaltic material a plausible hypothesis is that the surface of vesta was punctured by large impacts in the past which dispersed fragments of its basaltic crust into space and produced one of the most prominent asteroid families ever created in the belt until recently vesta was the only known object in the asteroid belt which underwent differentiation and survived to the present epoch since 2000 many new small basaltic asteroids have been discovered in the inner and outer parts of the asteroid belt possibly representing fragments from distinct differentiated bodies these discoveries may help us to better understand the number and nature of objects in the inner solar system that underwent geological differentiation to investigate these issues we performed extensive numerical simulations whose aim was to reproduce as precisely as possible the dynamical evolution of vesta s ejected fragments over timescales comparable to the family s age specifically we numerically integrated the orbital evolution of 6600 test bodies with orbits that started within the vesta family and dynamically evolved over 2 gy our model included gravitational perturbation of all planets except mercury and the yarkovsky effect the results show that a relatively large fraction of the original vesta family members may have evolved out of the family borders defined by clustering algorithms and are now dispersed over the inner asteroid belt we compared the orbital distribution of our model fragments with the orbital locations of known basaltic asteroids in various parts of the inner main belt to find that i most basaltic asteroids with semimajor axis a 2 3 au located outside the vesta family s borders in the inner main belt including 809 lundia and 956 elisa are most likely fugitives from the vesta family that have evolved to their current orbits via various identified dynamical pathways our results also suggest that the vesta family is at least 1 gy old ii interestingly orbits of many basaltic asteroids with 2 3 a 2 5 au like those of 4796 lewis and 5379 abehiroshi are displaced from the vesta family to low inclinations and are not obtained in our simulations with sufficient efficiency we propose that i these small basaltic asteroids may be fragments of differentiated bodies other than 4 vesta or ii they were liberated from the vesta s surface before or during the late heavy bombardment epoch 3 8 gy ago and their orbital inclinations separated from that of vesta when secular resonances swept through the region

effects of temperature on remotely sensed mineral absorption features laboratory spectral reflectance of mafic silicates has been measured over a temperature range characteristic of solar system objects to study the variation of diagnostic mineral absorption bands this information has become increasingly important with recent improvements in the quality of remotely sensed planetary data and the concurrent increase in sophistication of quantitative and qualitative spectrum analysis techniques in this study visible and near ir reflectance spectra 0 4 2 5 m of pyroxenes and olivine were obtained over a sample temperature range of 80 448 k these are the first published reflectance data for these minerals at temperatures significantly below ambient 300 k additionally thermal radiation emitted from the samples at elevated temperatures was effectively removed disclosing for the first time the high temperature reflectance behavior of pyroxenes in the diagnostic 2 m spectral region as expected from basic physical considerations fe2 crystal field absorptions in all samples become narrower with decreasing temperature the three components of the composite olivine band centered near 1 m become better resolved with decreased temperature and show changes in relative absorption strength there is not however any significant wavelength shift of the olivine reflectance minimum both orthopyroxene and clinopyroxene spectra show dramatic changes in band symmetry with temperature with the greatest change in the longer wavelength edge despite these significant changes in shape little if any change is observed in the wavelength position of reflectance minima of pyroxene absorptions near 1 m the 2 m pyroxene absorptions in contrast demonstrate major shifts of reflectance minima but in different directions in orthopyroxene spectra the band shifts to longer wavelengths with increased temperature while for the clinopyroxene spectra the band shifts to shorter wavelengths this behavior results in greatly improved spectral differentiation of orthopyroxene and clinopyroxene components in a mixture such as a basalt at reduced temperatures application of the results presented here to remote sensing mineral characterization techniques currently in use for determination of pyroxene composition can provide a moderate improvement to quantitative interpretations from 5 to 20 wt feo for orthopyroxenes and 5 wt cao for clinopyroxenes depending on planetary surface temperature

first tomographic image of ionospheric outflows 1 an image of the dayside low energy ion outflow event that occurred on 16 december 2003 was constructed with ground and space based gps global positioning system total electron content tec data and ion drift meter data from the dmsp defense meteorological satellite program a tomographic reconstruction technique has been applied to the gps tec data obtained from the gps receiver on the low earth orbit leo satellite fedsat the two dimensional tomographic image of the topside ionosphere and plasmasphere reveals a spectacular beam like dayside ion outflow emanating from the cusp region the transverse components of the magnetic field in fedsat s newmag data show the presence of field aligned current fac sheets indicating the existence of low energy electron precipitation in the cusp region the dmsp ion drift data show upward ion drift velocities and upward fluxes of low energy ions and electrons at the orbiting height of the dmsp spacecraft in the cusp region this study presents the first tomographic image of the flux tube structure of ionospheric ion outflows from 0 13 re up to 3 17 re altitude