a magnetic anomaly associated with an albedo feature near airy crater in the lunar nearside highlands 1 we describe a strong crustal magnetic anomaly recently identified in lunar prospector magnetometer data that is associated with a previously unreported albedo feature near the crater airy in the lunar nearside highlands other workers have demonstrated a correlation between magnetic anomalies and the enigmatic bright markings known as lunar swirls we have used earth based telescopic spectra and clementine multispectral images to investigate the compositional and optical maturity characteristics of the airy swirl the airy albedo feature does not exhibit the complex sinuous structure of well known swirls such as the reiner gamma formation but does possess a bright loop and central dark lane another strong magnetic anomaly in the apollo 16 descartes region corresponds to a simple diffuse bright albedo spot on this basis we suggest that a continuum of swirl morphologies exists on the moon with the airy feature representing an intermediate or incipient swirl form

lunar optical maturity investigations a possible recent impact crater and a magnetic anomaly 1 we have used maps of the omat optical maturity parameter along with other clementine uv vis image products to study two interesting lunar features related to albedo and optical maturity examination of the region of a small crater whose formation has been suggested to be a candidate for the flash photographed in 1953 by stuart demonstrates that the candidate crater is not unusually fresh compared to other small craters in the vicinity therefore it is unlikely that the formation of this impact crater generated the observed flash an area of unusually high albedo in the descartes highlands is also known to be a magnetic anomaly it has been proposed that the presence of the magnetic anomaly has prevented the solar wind from reaching the surface for billions of years and therefore that the area has not undergone normal space weathering and preserved a high albedo the high albedo is caused only by maturity differences with the surroundings not by an exotic composition the fact that the albedo anomaly has not darkened or reddened to the extent expected may be the result of the surface texture as revealed in 3 8 cm radar images we suggest that the fresh appearance is largely caused by overlapping ejecta from two nearby craters and continual exposure of immature material by the erosion of 1 to 10 cm sized fragments within the deposit the magnetic shielding mechanism if operative probably plays only a minor role in producing the descartes albedo anomaly

identification of the lunar flash of 1953 with a fresh crater on the moon s surface abstract a 1953 telescopic photograph of a flash on the moon is the only unequivocal record of the rare crash of an asteroid sized body onto the lunar surface we estimate that this event would create an impact feature up to several km in size and that the diameter of the impacting body would be about 20 m such an event would cause regional devastation if it occurred on earth although not detectable with ground based telescopes the lunar crater should be visible in space based images of the moon a search of images from the clementine mission reveals an 1 5 km high albedo blue fresh appearing crater with an associated ejecta blanket at the location of the flash the identification of this crater offers an opportunity to investigate subsurface unaltered lunar soils

remote sensing and geologic studies of the schiller schickard region of the moon near infrared reflectance spectra multispectral images and photogeologic data for the schiller schickard ss region were obtained and analyzed in order to determine the composition and origin of a variety of geologic units these include light plains deposits orientale related deposits mare units and dark haloed impact craters dhcs spectral data indicate that the pre orientale highland surface was dominated by noritic anorthosite near ir spectra show that dhcs in the region have excavated ancient 3 8 ga mare basalts from beneath highland bearing material emplaced by the orientale impact ancient mare basalts were widespread in the ss region prior to the orientale event and their distribution appears to have been controlled by the presence of several old impact basins including the schiller zucchius basin and a basin previously unrecognized both near ir spectra and multispectral images indicate that light plains and other orientale related units in the ss region contain major amounts of local pre orientale mare basalt the amounts of local material in these deposits approach but seldom exceed the maximum values predicted by the local mixing hypothesis of oberbeck and co workers

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

a compositional study of the aristarchus region of the moon using near infrared reflectance spectroscopy newly obtained near infrared reflectance spectra for features on or near the aristarchus plateau demonstrate the diversity of compositions in the region highland units are of three probable compositions a feldspar and clinopyroxene assemblage a probable clinopyroxene olivine and possibly feldspar assemblage and an assemblage composed of olivine or olivine and feldspar the feldspar clinopyroxene assemblage is tentatively correlated with the major th anomaly centered on aristarchus crater the regional pyroclastic deposits on the plateau are composed of greater than 90 fe2 bearing glass the aristarchus cratering event fully penetrated any mare or pyroclastics in the target evidence for mare related material is found in the ejecta on the mare side of the mare plateau contact

space weathering on airless bodies resolving a mystery with lunar samples using new techniques to examine the products of space weathering of lunar soils we demonstrate that nanophase reduced iron npfe0 is produced on the surface of grains by a combination of vapor deposition and irradiation effects the optical properties of soils both measured and modeled are shown to be highly dependent on the cumulative amount of npfe0 which varies with different starting materials and the energetics of different parts of the solar system the measured properties of intermediate albedo asteroids the abundant s type asteroids in particular are shown to directly mimic the effects predicted for small amounts of npfe0 on grains of an ordinary chondrite regolith this measurement and characterization of space weathering products seems to remove a final obstacle hindering a link between the abundant ordinary chondrite meteorites and common asteroids

initial mapping and interpretation of lunar crustal magnetic anomalies using lunar prospector magnetometer data maps of relatively strong crustal magnetic field anomalies detected at low altitudes with the magnetometer instrument on lunar prospector are presented on the lunar nearside relatively strong anomalies are mapped over the reiner gamma formation on western oceanus procellarum and over the rima sirsalis rille on the southwestern border of oceanus procellarum the main rima sirsalis anomaly does not correlate well with the rille itself but is centered over an imbrian aged smooth plains unit interpreted as primary or secondary basin ejecta the stronger reiner gamma anomalies correlate with the locations of both the main reiner gamma albedo marking and its northeastward extension both the rima sirsalis and the reiner gamma anomalies are extended in directions approximately radial to the center of the imbrium basin this alignment suggests that imbrium basin ejecta materials lying in many cases beneath the visible mare surface are the sources of the nearside anomalies if so then the albedo markings associated with the stronger refiner gamma anomalies may be consistent with a model involving magnetic shielding of freshly exposed mare materials from the solar wind ion bombardment two regions of extensive magnetic anomalies are mapped in regions centered on the ingenii basin on the south central farside and near the crater gerasimovic on the southeastern farside these regions are approximately antipodal to the imbrium and crisium basins respectively the imbrium antipode anomaly group is the most areally extensive on the moon while the largest anomaly in the crisium antipode group is the strongest detected by the lunar prospector magnetometer a consideration of the expected antipodal effects of basin forming impacts as well as a combination of sample data and orbital measurements on the nearside leads to the conclusion that the most probable sources of magnetic anomalies in these two regions are ejecta materials from the respective impacts in both regions the strongest individual anomalies correlate with swirl like albedo markings of the reiner gamma class visible on available orbital photography

mapping of crustal magnetic anomalies on the lunar near side by the lunar prospector electron reflectometer lunar prospector lp electron reflectometer measurements show that surface fields are generally weak in the large mare basalt filled impact basins on the near side but are stronger over highland terranes especially those lying antipodal to young large impact basins between the imbrium and nectaris basins many anomalies correlate with the cayley and descartes formations statistical analyses show that the most strongly magnetic nearside terranes are cayley type light plains terra materials and pre imbrian craters light plains and terrae include basin impact ejecta as a major component suggesting that magnetization effects from basin forming impacts were involved in their formation the magnetization of pre imbrian craters however may be evidence of early thermal remanence relatively strong small scale magnetic anomalies are present over the reiner gamma feature on western oceanus procellarum and over the rima sirsalis rille on the southwestern border of procellarum both apollo subsatellite and lp data show that the latter anomaly is nearly aligned with the rille though lp magnetometer and reflectometer data show that the anomaly peak is actually centered over a light plains unit this anomaly and the reiner gamma anomaly are approximately radially aligned with the center of imbrium suggesting an association with ejecta from this basin

optical maturity of ejecta from large rayed lunar craters lucey et al 2000 have developed a methodology for extracting an optical maturity parameter omat from multispectral clementine images the omat parameter characterizes the overall maturity of lunar soils and crater ejecta by changes in reflectance spectra using these omat images we surveyed large craters 20 km diameter on the moon that had previously been mapped as possessing or possibly possessing rayed ejecta we generated average radial profiles of omat values for rays of these large craters from these profiles we classified the craters into three relative age groups 1 older than copernicus inferred age of 810 myr 2 intermediate and 3 as young or younger than tycho inferred age of 109 myr we suspect that there is a bias to our classification scheme such that the omat profiles of smaller craters look like that of larger but older craters nevertheless some large craters such as eudoxus 67 km and aristillus 55 km are now known from this study to have optically mature ejecta and therefore are suspected to be older than copernicus this is consistent with an age of 1 3 gyr suggested for aristillus by ryder et al 1991 such craters were included by mcewen et al 1997 when estimating the density of craters younger than or contemporaneous with copernicus therefore the case for a modest increase in the cratering rate in the past 800 myr versus the previous 2 4 gyr indicated from that work has been weakened grier and mcewen 2001 given current constraints on dating large and recent lunar craters we cannot support or disprove the hypothesis that there has been a significant increase in the rate of large terrestrial impact events in the past 100 400 myr

space weathering from mercury to the asteroid belt the variety of evidence bearing on the nature of space weathering is reviewed the effects of space weathering include spectral darkening reddening and subdued absorption bands and the distinctive magnetic electron spin resonance caused by single domain metallic iron particles ever since the apollo missions two paradigms have dominated the thinking of the planetary science community concerning space weathering 1 the optical effects are caused by impact vitrified glass in agglutinates and 2 the submicroscopic metallic iron results from the reduction of ferrous iron by the impact melting of minerals whose surfaces have been saturated with hydrogen from the solar wind however studies carried out since the apollo program showed that both of these paradigms are invalid a hypothesis first suggested by the author and his colleagues 26 years ago but not generally accepted at that time now appears to be essentially correct both the optical and magnetic effects are caused by metallic iron particles smaller than the wavelength in ubiquitous vapor deposited coatings on soil particle surfaces and inside agglutinates the vapor is generated by both solar wind sputtering and micrometeorite impact vaporization and injected preferentially downward into the porous regolith the iron is reduced by a physical process the selective loss of oxygen that occurs during deposition of the vapor and does not require heating melting or a reducing environment a mathematical theory that describes the optical effects of the submicroscopic iron quantitatively is derived and applied to the regoliths of the moon mercury and an s asteroid

lacustrine environmental evolution and implications on source rock deposition in the upper cretaceous paleocene of the south yellow sea basin offshore eastern china abstract lacustrine source rocks are well developed within the upper cretaceous paleocene in the south yellow sea basin sysb in offshore eastern china understanding the deposition of these source rocks could provide critical information for hydrocarbon exploration in the sysb as well as reveal the paleoenvironment across the cretaceous paleogene boundary in eastern china this study investigates the lacustrine environmental evolution during the upper cretaceous taizhou formation k2t to paleocene funing formation e1f within the sysb and its implications on source rock deposition based on core observation combined with organic geochemical indicators multiple maturity parameters vitrinite reflectance tmax and biomarker isomerization ratios reveal that the organic matter om has reached early oil window maturity the om of source rocks is dominated by kerogen type ii iii liptinite and vitrinite anoxic saline brackish deep to semi deep lacustrine environments prevailed during the deposition of k2t2 second member of the k2t e1f2 second member of the e1f and e1f4l lower unit of fourth member of the e1f the deposition of three intervals was influenced by marine incursion as evidenced by geochemical and paleontological results low to moderate toc contents avg 0 78 wt to 1 91 wt which corresponds to low to moderate terrestrial om input are observed through three intervals abundant freshwater together with high terrestrial om flowed into the lacustrine environments during the deposition of e1f4u upper unit of fourth member of the e1f leading to dysoxic oxic and freshwater conditions high terrestrial om input is probably the major controlling factor for relatively high toc contents avg 2 49 in the e1f4u an evolution from balanced fill to overfilled lake type is observed in the upper cretaceous paleocene of sysb consistent with an evolution from semi arid to humid paleoclimate conditions the e1f4u and e1f2 source rocks exhibit fair to good potential whereas poor to fair potential is present in the e1f4l and k2t2 source rocks compared with the paleogene source rocks in onshore eastern china the upper cretaceous paleocene source rocks in the sysb probably hold good potential for generating commercial quantity of oil although further study on hydrocarbon generation kinetics of source rocks and overall basin history are needed

moon near infrared spectral reflectance a first good look a positive identification of the minerals olivine plagioclase and several types of pyroxenes were made at several locations on the lunar surface by using remote measurements for example the crater aristarchus is found to have an average pyroxene composition of augite and plagioclase is obviously present a dark mantle deposit in the crater j herschel is at least partly composed of a mixture of 70o7o olivine and 30o7o pyroxene these determinations were possible because the reflectance spectra for 10 20 km diameter lunar areas have been measured for the first time in the ir spectral region 0 65 2 5 m with sufficient spectral resolution and photometric precision to define mineral electronic absorption bands the reflectance for all lunar regions observed over 100 to present continues to increase toward longer wavelengths to at least 2 5 m and several mineral absorption bands appear the telescopic spectra are of similar quality and contain features similar to laboratory spectra of lunar samples the absorption features in several spectra have been quantitatively analyzed using newly developed computer processing techniques including thermal flux removal and absorption band fitting to produce these mineral identifications detection and quantitative analysis of these absorptions provide a much improved basis for remotely determining and mapping surface mineralogy quantitatively from the ground or using airborne or spacecraft platforms

mapping the feo and tio2 content of the lunar surface with multispectral imagery the derivation of quantitative elemental concentrations from multispectral imaging of the moon has long been a goal of lunar remote sensing concentration maps at the spatial resolutions available from the recent clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust lucey et al 1995 presented a method for extracting the concentration of fe from multispectral imaging of the moon this paper examines and quantifies important aspects ofthat technique left unexamined by lucey et al which had the potential to severely limit its utility these aspects include the effects of maturity grain size mineralogy shading due to topography and the presence of glass we also present a new algorithm for derivation of tio2 from multispectral imaging of both mare and highland units we find that both techniques are only weakly sensitive to maturity and that they have about 1 wt accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by blewett et al 1997 we also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by pieters and coworkers and hapke and coworkers we find the view of hapke and coworkers to be more consistent with our observations using a global mosaic of clementine multispectral data and these element derivation algorithms we find that the global modal abundance of feo is 4 5 wt 1 wt and the global modal abundance of tio2 is 0 45 wt 1 wt

numerical study of flow anisotropy within a single natural rock joint the paper investigates the flow anisotropy within a natural joint subjected to mechanical shear the cubic law is the simplest way to describe fluid flow through rock joints but because of rock wall roughness deviations from this model have been observed the reynolds equation usually gives better results in this study micro scale roughness is taken into account to define a reduced coefficient of permeability numerical simulations have been carried out by applying darcy s law to the rock joint described as an equivalent porous medium the numerical simulations are based on experimental data obtained by hans phd grenoble 2002 from a series of hydromechanical shear tests on a rock joint replica the numerical results have been compared to the experimental ones and to the results obtained by applying the reynolds equation to assess the relevance of the simulations for the fracture studied the approach proposed herein can reproduce relatively well the experimental flow anisotropy and provides consistent values of flow rates whereas the reynolds equation tends to give higher flow rates

imaging of lunar surface maturity the physical evolution of the lunar surface with exposure to the space environment is termed maturation and maturity is the degree to which a particular lunar soil possesses quantitative characteristics consistent with that exposure several quantitative measures or indices of maturity have been proposed and employed including the abundance of solar wind gas abundance of various types of agglutinates various measures of grain size and is feo among the changes attendant with space exposure are striking changes in the optical characteristics of soils mature lunar soils are dark red and exhibit reduced spectral contrast relative to immature soils this paper presents an optical maturity index that quantifies the spectral effects of maturation we show that this optical maturity index correlates with other maturity indices about as well as the accepted maturity indices correlate among themselves and is only weakly coupled to composition the modest correlations among maturity indices suggest important controls on individual maturity indices other than age uncorrelated variations in the rates of accumulation of individual indicators or variations in depths over which indicators are emplaced in addition to mixing these effects conspire to reduce the equivalence of maturity and duration of surface exposure optical maturity illustrates some of these effects showing that ejecta of large and small craters mature at different rates and that the interiors and ejecta of large craters exhibit systematically different optical maturities the same or analogous effects are likely to influence other maturity indices

abundance and distribution of iron on the moon the abundance and distribution of iron on the moon is derived from a near global data set from clementine the determined iron content of the lunar highlands crust 3 percent iron by weight supports the hypothesis that much of the lunar crust was derived from a magma ocean the iron content of lower crustal material exposed by the south pole aitken impact basin on the lunar farside is higher 7 to 8 percent by weight and consistent with a basaltic composition this composition supports earlier evidence that the lunar crust becomes more mafic with depth the data also suggest that the bulk composition of the moon differs from that of the earth9s mantle this difference excludes models for lunar origin that require the earth and moon to have the same compositions such as fission and coaccretion and favors giant impact and capture

composition and exposure age of the apollo 16 cayley and descartes regions from clementine data normalizing the optical effects of space weathering in order to quantitatively assess the composition of the lunar surface from reflectance spectroscopy it is necessary to be able to differentiate between the optical effects due to composition and those due to exposure to space weathering processes laboratory analyses of returned lunar soils are used to show that limited quantitative compositional information and the exposure age of the lunar surface can be determined using straightforward calculations from remotely acquired reflectance data sampled with a small number of spectral channels exposure age approximated by is feo where is is the characteristic ferromagnetic signal from single domain iron metal is estimated using a ratio of the reflectance at a wavelength outside of the 1 m ferrous iron absorption band to the reflectance at a wavelength within the band the iron plus titanium content of a soil can then be calculated from its is feo and reflectance these combined techniques are applied to clementine uvvis multispectral data of the lunar highlands in the vicinity of the apollo 16 landing site the is feo and feo tio2 contents are calculated for this region materials associated with recently formed impact craters and recent and or ongoing downslope movement are easily detected as nonmature the feo tio2 content of the descartes mountains is found to be 1 2 wt less than the cayley plains west of the apollo 16 landing site localized areas of compositional heterogeneity associated with some small impact events are also revealed a model for normalizing the optical contribution due to exposure to space weathering processes is applied to the clementine uvvis data in order to bring the data to an equivalent mature exposure state this approach allows residual spectral differences between the observed materials to be confidently interpreted as being due to compositional differences alone rather than to differences both of composition and of exposure the exposure normalized data reveal that this region of the highlands is characterized by limited large scale compositional heterogeneity that is detectable by a small number of spectral bandpasses the descartes mountains are identified as being more anorthositic than the cayley plains units most small impacts in the region excavated material compositionally similar to material surrounding them with the notable exceptions of the impacts that created south ray crater and an unnamed crater on the floor of abulfeda

correlation of a strong lunar magnetic anomaly with a high albedo region of the descartes mountains 1 mapping and model simulations of lunar prospector magnetometer measurements show that the source of the strongest known magnetic anomaly on the lunar near side 42 nanoteslas at 18 6 km altitude coincides approximately with a high albedo region of the descartes mountains centered 60 km south southeast of the apollo 16 landing site the descartes mountains represent primary ejecta from one or more basin forming events imbrium and or nectaris supporting the hypothesis that basin ejecta materials emplaced 3 8 gyr ago are the main sources of lunar magnetic anomalies the higher albedo of the surface at this location is consistent with a significant role for solar wind ions in the optical maturation or space weathering of the lunar surface

an analysis of the mariner 10 color ratio map of mercury abstract the results of a geological analysis of the mariner 10 orange uv color ratio man of mercury b hapke c christman b rava and j mosher proc lunar planet sci conf 11th 1980 pp 817 822 are given certain errors that occured in reproducing the published version of the 1980 map are pointed out the relationships between color and terrain are distinctly nonlunar there is no correlation between color boundaries and the smooth plains on mercury in contrast to the strong correlation between color and maria highlands contacts on the moon there are no large exposures of low albedo blue material that could be considered to be mercurian analogs of high fe ti lunar maria basalts on any part of mercury imaged by mariner 10 three lines of evidence imply that the crust is low in fe2 and ti4 rays and ejecta blankets are bluer than most areas on mercury the fe2 band in mercury s reflectance spectrum is very weak or nonexistent and the albedo contrasts are smaller than those on the moon there is no evidence in the spectral or albedo data that a lunar type of second wave of melting ever occured on mercury rather the observations are most consistent with the hypothesis that the smooth plains are extrusive landforms derived from local material possibly mobilized by the caloris event in several places correlations between color and topography can be explained if older redder higher fe materials underlie younger bluer lower fe surfaces there is some evidence of late fe rich pyroclastic like activity

lunar iron and titanium abundance algorithms based on final processing of clementine ultraviolet visible images the clementine mission to the moon returned global imaging data collected by the ultraviolet visible uvvis camera this data set is now in a final state of calibration and a five band multispectral digital image model dim of the lunar surface will soon be available to the science community we have used observations of the lunar sample return sites and stations extracted from the final dim in conjunction with compositional information for returned lunar soils to revise our previously published algorithms for the spectral determination of the feo and tio2 content of the lunar surface the algorithms successfully normalize the effects of space weathering so that composition may be determined without regard to a surface s state of maturity these algorithms permit anyone with access to the standard archived dim to construct high spatial resolution maps of feo and tio2 abundance such maps will be of great utility in a variety of lunar geologic studies

clementine images of the lunar sample return stations refinement of feo and tio2 mapping techniques clementine uvvis images of the lunar sample return sites have been processed and used to produce refined calibrations for the iron and titanium determination algorithms of lucey et al 1995 1996 the high spatial resolution of the clementine data permits individual sampling stations to be resolved at the apollo 15 16 and 17 landing sites we find an excellent linear correlation between the spectral fe and ti parameters and the average feo and tio 2 contents of soils sampled at each site or station this correlation demonstrates that these techniques can confidently be applied to other areas of the moon the luna 24 site does not fit the ti relation found for other sites suggesting that either its sample is nonrepresentative or the reported landing coordinates are incorrect

remote sensing of lunar pyroclastic mantling deposits abstract mantling deposits on the moon are considered to be pyroclastic units emplaced on the lunar surface as a result of explosive fire fountaining these pyroclastic units are characterized as having low albedos having smooth fine textured surfaces and consisting in part of homogeneous febearing volcanic glass and partially crystallized spheres mantling units exhibit low returns on depolarized 3 8 cm radar maps indicating an absence of surface scatterers in the 1 to 50 cm size range a number of reflectance spectra from several regional pyroclastic deposits are presented for the first time these data support a previous interpretation that mantling units have a unique spectral signature which is indicative of the presence of a significant fe bearing volcanic glass component the rima bode region is discussed as an example of an area in which several types of remote sensing data including 3 8 cm radar spectral reflectance and multispectral vidicon data were used to reconstruct the geologic events surrounding the emplacement of a regional pyroclastic mantling deposit the recognition of numerous varieties of volcanic glass samples especially relatively high albedo e g green yellow glasses suggests the existence of additional unrecognized mantling deposits with albedos higher than those studied to date on the basis of the remote sensing data summarized and presented five new areas have been identified which may represent higher albedo regional pyroclastic deposits

composition of the lunar highland crust from near infrared spectroscopy near infrared reflectance spectra of the lunar highlands are synthesized to obtain global information about the composition of the lunar near side crust immature exposed surfaces from small fresh craters mountains and massifs and large craters with central peaks are included in a survey of rock types across the lunar near side compositions recognized in these data include anorthosite noritic gabbric and troctolitic mineral assemblages three quarters of the areas studied that represent samples from the upper 1 2 km of lunar crust exhibit noritic compositions with different amounts of pyroxene and or brecciation alteration norites are ubiquitous across the near side and show no spatial clustering associated with any of the major basins in contrast to this noritic megaregolith of the upper crust material representing stratigraphically deeper zones 5 15 km of the lunar crust is dominated by gabbros anorthosites and troctolites with less than a quarter of the areas studied exhibiting a noritic composition the origin of the noritic megaregolith and its relation to deeper crustal material is thus somewhat of an enigma the current limited statistics for areas identified as anorthosites and troctolites are insufficient to derive global spatial distributions gabbroic areas however are notably concentrated in the western hemisphere although incomplete for a global assessment of crustal materials these data demonstrate that the lunar near side crust is clearly mineralogically heterogeneous both laterally and vertically and not well mixed below 1 2 km

the origin of lunar crater rays abstract lunar rays are filamentous high albedo deposits occurring radial or subradial to impact craters the nature and origin of lunar rays have long been the subjects of major controversies we have determined the origin of selected lunar ray segments utilizing earth based spectral and radar data as well as feo tio 2 and optical maturity maps produced from clementine uvvis images these include rays associated with tycho olbers a lichtenberg and the messier crater complex it was found that lunar rays are bright because of compositional contrast with the surrounding terrain the presence of immature material or some combination of the two mature compositional rays such as those exhibited by lichtenberg crater are due entirely to the contrast in albedo between ray material containing highlands rich primary ejecta and the adjacent dark mare surfaces immaturity rays are bright due to the presence of fresh high albedo material this fresh debris was produced by one or more of the following 1 the emplacement of immature primary ejecta 2 the deposition of immature local material from secondary craters 3 the action of debris surges downrange of secondary clusters and 4 the presence of immature interior walls of secondary impact craters both composition and state of maturity play a role in producing a third combination class of lunar rays the working distinction between the eratosthenian and copernican systems is that copernican craters still have visible rays whereas eratosthenian aged craters do not compositional rays can persist far longer than 1 1 ga the currently accepted age of the copernican eratosthenian boundary hence the mere presence of rays is not a reliable indication of crater age the optical maturity parameter should be used to define the copernican eratosthenian boundary the time required for an immature surface to reach the optical maturity index saturation point could be defined as the copernican period

lunar swirls examining crustal magnetic anomalies and space weathering trends 1 we have used multispectral images from clementine and data from lunar prospector s magnetometer to conduct a survey of lunar crustal magnetic anomalies prominent lunar swirls and lesser known swirl markings to provide new information on the nature of swirls and their association with magnetic anomalies we find that all swirls and swirl like albedo patterns are associated with areas of magnetized crust but not all areas of magnetized crust are colocated with swirl like albedo anomalies all observed swirls exhibit spectral characteristics similar to immature material and generally have slightly lower feo values compared with their surroundings as determined with a multispectral iron mapping method we discuss these results in relation to the various hypotheses for swirl formation the comet impact hypothesis for lunar swirls would not predict a difference in the spectrally determined feo content between swirls and nearby ordinary surfaces the compositional difference could be explained as a consequence of 1 magnetic shielding of the surface from the solar wind which could produce anomalous space weathering little darkening with limited reddening and potentially alter the predictions of the multispectral iron mapping algorithm while the compositional contrast could be enhanced by delivery of lower feo ejecta from outside the swirl and 2 accumulation of fine plagioclase rich dust moving under the influence of electric fields induced by solar wind interactions with a magnetic anomaly therefore we cannot at present clearly distinguish between the solar wind shielding and electrostatic dust accumulation models for swirl formation we describe future measurements that could contribute to solution of the puzzle of swirl origin