diviner lunar radiometer observations of cold traps in the moon s south polar region diviner lunar radiometer experiment surface temperature maps reveal the existence of widespread surface and near surface cryogenic regions that extend beyond the boundaries of persistent shadow the lunar crater observation and sensing satellite lcross struck one of the coldest of these regions where subsurface temperatures are estimated to be 38 kelvin large areas of the lunar polar regions are currently cold enough to cold trap water ice as well as a range of both more volatile and less volatile species the diverse mixture of water and high volatility compounds detected in the lcross ejecta plume is strong evidence for the impact delivery and cold trapping of volatiles derived from primitive outer solar system bodies

how old are young lunar craters 1 the accurate definition of the lunar cratering chronology is important for deriving absolute model ages across the lunar surface and throughout the solar system images from the lunar reconnaissance orbiter narrow angle cameras and wide angle camera and the selene kaguya terrain camera provide new opportunities to investigate crater size frequency distributions csfds on individual geological units at lunar impact craters we report new csfd measurements for the copernican aged craters north ray tycho and copernicus which are crucial anchor points for the lunar cratering chronology we also discuss possible reasons for an age discrepancy observed between the impact melt and ejecta units our csfds for north ray and tycho crater ejecta deposits are consistent with earlier measurements however for copernicus crater and one of its rays we find significantly lower cumulative crater frequencies than previous studies our new results for copernicus crater fit the existing lunar absolute chronologies significantly better than the previous counts our derived model ages of the ejecta blankets of north ray tycho and copernicus agree well with radiometric and exposure ages of the apollo 16 17 and 12 landing sites respectively and are generally consistent with a constant impact rate over the last 3 ga however small variations of the impact rate cannot be resolved in our data and require further investigations

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

unravelling the mystery of lunar anomalous craters using radar and infrared observations in miniature radio frequency mini rf radar images anomalous craters are those having a high circular polarization ratio cpr in their interior but not exterior to their rims previous studies found that most cpr anomalous craters contain permanently shadowed regions psrs and that their population is overabundant in the polar regions however there is considerable controversy in the interpretation of these signals both water ice deposits and rocks surface roughness have been proposed as the source of the elevated cpr values to resolve this controversy we have systematically analyzed 4000 impact craters with diameters between 2 5 and 24 km in the mini rf radar image and diviner rock abundance ra map we first constructed two controlled orthorectified global mosaics using 6818 tracks of mini rf raw data and then analyzed the correlations between radar cpr and surface slope rock abundance and depth diameter ratios of impact craters our results show that cpr anomalous craters are distributed relatively uniformly across the lunar surface with no apparent difference in cpr between the polar potentially icy and non polar not icy craters most cpr anomalous craters are relatively young with a large depth diameter ratio and they actually represent an intermediate stage of crater evolution comparison with a two component radar scattering model suggests that rocks and surface roughness are major contributors to the observed cpr values using craters of 4 7 22 km in diameter with known ages we find that craters spend up to 120 ma with a high exterior ra and 3 ga in the cpr anomalous phase

composition of orientale basin deposits and implications for the lunar basin forming process the orientale basin on the lunar western limb has served as the prototype lunar multiring basin for many years in order to constrain possible models of the formation and excavation of basin ejecta we have studied the composition of orientale basin deposits using both earth based spectral reflectance and apollo orbital geochemical data results indicate that orientale basin ejecta are dominantly anorthositic with compositions ranging from pure anorthosite to noritic anorthosite although minor quantities of mare basalt and low k fra mauro basalt are present ultramafic and kreep components appear to be absent portions of the inner rings of the basin may be composed of anorthosite whose shock levels exceed 20 gpa 200 kbar in conjunction with photogeologic evidence for the preservation of prebasin topography and structure within the cordillera basin ring we suggest that the diameter of the excavation crater of the orientale basin is on the order of 500 to 600 km effective depths of excavation are probably less than about half the local crustal thickness which in this region is on the order of 100 km we find that the orientale impact excavated dominantly upper crustal rocks with a depth of excavation consistent with a proportional growth basin forming model

lunar surface rock abundance and regolith fines temperatures derived from lro diviner radiometer data 1 surface temperatures derived from thermal infrared measurements provide a means of understanding the physical properties of the lunar surface the contrasting thermophysical properties between rocks and regolith fines cause multiple temperatures to be present within the field of view of nighttime multispectral data returned from the lunar reconnaissance orbiter lro diviner radiometer between 60 n s latitudes regolith temperatures are influenced by the presence of rocks in addition to factors such as the thermophysical properties of the regolith fines latitude and local slopes and radiative heating from adjacent crater walls preliminary comparisons of derived rock concentrations with lro camera images show both qualitative and quantitative agreement although comparisons of derived rock concentrations with circular polarization ratio radar data sets display general similarities there are clear differences between the two data sets in the relative magnitude and areal extent of rocky signatures several surface units can be distinguished based on their regolith temperature and rock concentration values and distributions including maria and highlands surfaces rocky impact craters rilles and wrinkle ridges dark mantled deposits and isolated cold surfaces rock concentrations are correlated with crater age and rocks are only preserved on the youngest surfaces or where steep slopes occur and mass wasting prevents mantling with fines the presence of rocky surfaces excavated by young impacts allows for the estimation of minimum regolith thickness from the size of the impact the derived rock concentrations confirm the presence of thicker regolith cover in the highlands and in locations of radar dark haloes

characterization of previously unidentified lunar pyroclastic deposits using lunar reconnaissance orbiter camera data 1 we used a lunar reconnaissance orbiter camera lroc global monochrome wide angle camera wac mosaic to conduct a survey of the moon to search for previously unidentified pyroclastic deposits promising locations were examined in detail using lroc multispectral wac mosaics high resolution lroc narrow angle camera nac images and clementine multispectral ultraviolet visible or uvvis data out of 47 potential deposits chosen for closer examination 12 were selected as probable newly identified pyroclastic deposits potential pyroclastic deposits were generally found in settings similar to previously identified deposits including areas within or near mare deposits adjacent to highlands within floor fractured craters and along fissures in mare deposits however a significant new finding is the discovery of localized pyroclastic deposits within floor fractured craters anderson e and f on the lunar farside isolated from other known similar deposits our search confirms that most major regional and localized low albedo pyroclastic deposits have been identified on the moon down to 100 m pix resolution and that additional newly identified deposits are likely to be either isolated small deposits or additional portions of discontinuous patchy deposits

the miniature radio frequency instrument s mini rf global observations of earth s moon abstract radar provides a unique means to analyze the surface and subsurface physical properties of geologic deposits including their wavelength scale roughness the relative depth of the deposits and some limited compositional information the nasa lunar reconnaissance orbiter s lro miniature radio frequency mini rf instrument has enabled these analyses on the moon at a global scale mini rf has accumulated 67 coverage of the lunar surface in s band 12 6 cm radar with a resolution of 30 m pixel here we present new mini rf global orthorectified uncontrolled s band maps of the moon and use them for analysis of lunar surface physical properties reported here are readily apparent global and regional scale differences in lunar surface physical properties that suggest three distinct terranes namely a 1 nearside radar dark region 2 orientale basin and continuous ejecta and the 3 highlands radar bright region integrating these observations with new data from lro s diviner radiometer rock abundance maps as well clementine and lunar prospector derived compositional values show multiple distinct lunar surface terranes and sub terranes based upon both physical and compositional surface properties previous geochemical investigations of the moon suggested its crust is best divided into three to four basic crustal provinces or terranes feldspathic highlands terrane an and outer procellarum kreep terrane and south pole aitken terrane that are distinct from one another however integration of these geochemical data sets with new geophysical data sets allows us to refine these terranes the result shows a more complex view of these same crustal provinces and provides valuable scientific and hazard perspectives for future targeted human and robotic exploration

lunar surface roughness derived from lro diviner radiometer observations abstract sunlit and shaded slopes have a variety of temperatures based on their orientation with respect to the sun generally greater slope angles lead to higher anisothermality within the field of view this anisothermality is detected by measuring changing emitted radiance as a function of viewing angle or by measuring the difference in brightness temperatures with respect to observation wavelength thermal infrared measurements from the lunar reconnaissance orbiter diviner radiometer were used to derive lunar surface roughness via two observation types 1 nadir multispectral observations with full diurnal coverage and 2 multiple emission angle targeted observations measurements were compared to simulated radiance from a radiative equilibrium thermal model and gaussian slope distribution model nadir observations most closely match a 20 rms slope distribution and multiple emission angle observations can be modeled using 20 35 rms slope distributions limited sampling of the lunar surface did not show any clear variation in roughness among surface units two dimensional modeling shows that surfaces separated by distances greater than 0 5 5 mm can remain thermally isolated in the lunar environment indicating the length scale of the roughness features non equilibrium conditions are prevalent at night and near sunrise and sunset preventing the use of the equilibrium thermal model for roughness derivations using data acquired at these local times multiple emission angle observations also show a significant decrease in radiance at high emission angles in both daytime and nighttime observations and hemispherical emissivity is lower than is apparent from nadir observations these observations and models serve as a basis for comparison with similar measurements of other airless bodies and as an initial template for the interpretation of tir measurements acquired under a variety of geometric conditions

on the response of a buoyant plume to downwelling favorable wind stress here the responseof a coastallytrappedbuoyantplume to downwelling favorablewind forcingis explored using a simplified two dimensional numerical model and a prognostic theory for the resulting width depth and density anomaly and along shelf transport of the plume consistent with the numerical simulations the analytical model shows that the wind causes mixing of the plume water and that the forced cross shelf circulation can also generate significant deepening and surface narrowing as well as increased along shelf transport the response is due to a combination of the purely advective process that leads to the steepeningof the isopycnals and the entrainment of ambient water into the plume the advective component depends on the initial plume geometry plumes that have a large fraction of their total width in contact with the bottom bottom trapped suffer relatively small depth and width changes compared to plumes that have a large fraction of their total width detached from the bottom surface trapped key theoretical parameters are wg wa theratioofthewidthoftheplumedetachedfromthebottomtothewidthoftheplumein contactwith it and the ratio of the wind generated mixed layer de to the initial plume depth hp which determines the amountofwaterinitiallyentrainedintotheplume themodelresultsalsoshowthatthecross shelfcirculation can be strongly influenced by the wind driven response in combination with the geostrophic shear of the plume the continuous entrainment into the plume as well as transient events is also discussed

constraints on the recent rate of lunar ejecta breakdown and implications for crater ages we present a new empirical constraint on the rate of breakdown of large ejecta blocks on the moon based on observations from the lunar reconnaissance orbiter lro diviner thermal radiometer we find that the rockiness of fresh crater ejecta can be quantified using the diviner derived rock abundance data set and we present a strong inverse correlation between the 95 th percentile value of the ejecta rock abundance ra 95 5 and crater age for nine craters with published model ages derived from crater counts on their continuous ejecta ra 95 5 decreases with crater age as age m y 0 46 this result implies shorter rock survival times than predicted based on downward extrapolation of 100 m crater size frequency distributions and represents a new empirical constraint on the rate of comminution of large rocks not previously analyzed experimentally or through direct observation in addition our result provides a new method for dating young lunar craters

a real time model of the seasonal temperature of lunar polar region and data validation a small tilt in the spin axis of the moon over the ecliptic plane causes seasonal incidence variation of solar illumination and especially causes significant temperature difference at the polar region in this article following the position of the subsolar point the real time model of solar illumination incidence over the moon polar region is developed based on this model with solving the 1 d heat conduction equation the seasonal temperature of the lunar surface is obtained and is in agreement with the diviner infrared ir data meanwhile using the fluctuation dissipation theorem and the wentzel kramers brillouin wkb approach for lunar regolith media the seasonal microwave mw brightness temperature tb is also obtained and validated by chang e 2 ce 2 37 ghz tb data these data also show that the lunar surface temperature and the mw tb even in the permanent shaded region psr undergo seasonal variation as well it might be due to the seasonal thermal radiation on the topographic psr coming from the sunlit crater walls caused by seasonal temperature variation the diviner ir data show that the highest temperature in the hermite a crater at the north polar psr can reach 109 k in summer

mapping and characterization of non polar permanent shadows on the lunar surface abstract we present the first globally complete inventory of permanent shadows on the lunar surface that are detectable with the current global instrument datasets including discovery of regions with persistent shadows over geologic time periods as close to the equator as 58 of latitude these results were obtained through application of a ray tracing technique to the latest global topographic datasets from the lunar reconnaissance orbiter our analysis reveals that 13 361 km2 of surface in the northern hemisphere and 17 698 km2 in the southern hemisphere are permanently shadowed we present maps showing the locations of all the permanent shadows detectable using these datasets then turn our focus toward the permanent shadows farthest from the poles each permanent shadow on the equator side of 65 of latitude is shown in detail surface brightness temperature data derived from the diviner mid infrared radiometer on board the lunar reconnaissance orbiter have been analyzed for four of these locations and found to have mid day temperatures 75 120 k less than nearby comparison locations that experience direct daytime illumination in some cases the permanently shadowed locations have nighttime temperatures 10 25 k lower than surroundings the temperature results support our finding that these non polar craters are permanently shadowed the surface brightness temperature results also raise interesting questions about their ability to cold trap volatiles discovery of these non polar permanently shadowed regions increases possible locations of water resources and high priority exploration targets on the moon

buried stratigraphic relationships along the southwestern shores of oceanus procellarum implications for early lunar volcanism the composition of mare highland boundaries is investigated in the region of southwestern oceanus procellarum using multispectral images from the galileo solid state imaging system the data are analyzed using a linear image based spectral mixture model to map the distribution and abundance of spectral end members representing mare basalt mature highland soils and fresh crater materials the fraction images that result from the mixture modeling are then integrated into a geographic information system database to analyze the relationship between the compositional gradients and regional geologic and geomorphic units within this framework three basic types of mixing gradients are recognized narrow mixing zones broad mixing zones and complex mixing zones the narrow zones appear to be the result of simple postformation lateral mass transport of surface materials due to the time averaged effects of impact cratering and regolith gardening the broad or moderate mixing zones exhibit evidence for significant incorporation of basalt into the distal basin ejecta of orientale and thus are interpreted to indicate that pre orientale volcanism and volcanic deposits were widespread in the procellarum region this is further corroborated by the mare rich ejecta blanket observed for the 100 km diameter impact crater letronne the complex mixing zones show evidence for extensive pre orientale and perhaps pre imbrium cryptomare as well as some volcanism extending into the late imbrian period these results indicate that mare highland boundaries frequently contain a convolved geologic record that allows insight into the geologic events prior to the final one apparently recorded by surface deposits for this region of the moon we now recognize that volcanism was well established and widespread in early imbrian time but had become more focused to a few major volcanic regions humorum procellarum by the late imbrian

influence of barotropic shear on the poleward advection of upper tropospheric air abstract the characteristics of the poleward advection of upper tropospheric air are investigated using meteorological analyses and idealized numerical models isentropic deformations of the tropopause during northern hemisphere winter are examined using maps of ertel s potential vorticity together with contour advection calculations large poleward excursions of upper tropospheric air are observed during rossby wave breaking events these poleward breaking events occur in regions of diffluence over the eastern atlantic ocean europe region and over the eastern pacific ocean north america region and the evolution of the tropospheric air depends on the local meridional shear in anticyclonic or weak cyclonic shear the tropospheric air tilts downstream broadens and wraps up anticyclonically whereas in cyclonic shear the tropospheric air tilts upstream thins and is advected cyclonically the role of ambient barotropic flow is further examined by considering the flow in two numerical models a pl

thickness of proximal ejecta from the orientale basin from lunar orbiter laser altimeter lola data implications for multi ring basin formation 1 quantifying the ejecta distribution around large lunar basins is important to understanding the origin of basin rings the volume of the transient cavity the depth of sampling and the nature of the basin formation processes we have used newly obtained altimetry data of the moon from the lunar orbiter laser altimeter lola instrument to estimate the thickness of ejecta in the region surrounding the orientale impact basin the youngest and best preserved large basin on the moon our measurements yield ejecta thicknesses of 2900 m near the cordillera mountains the topographic rim of orientale decaying to 1k m in thickness at a range of 215 km these measurements imply a volume of ejecta in the region from the cordillera ring to a radial range of one basin diameter of 2 9 10 6 km 3 and permit the derivation of an ejecta thickness decay model which can be compared with estimates for the volume of excavation and the size of the transient cavity these data are consistent with the outer rook mountains as the approximate location of the transient cavity s rim crest and suggest a volume of 4 8 10 6 km 3 for the total amount

lunar crater ejecta physical properties revealed by radar and thermal infrared observations abstract we investigate the physical properties and changes through time of lunar impact ejecta using radar and thermal infrared data we use data from two instruments on the lunar reconnaissance orbiter lro the diviner thermal radiometer and the miniature radio frequency mini rf radar instrument together with earth based radar observations we use this multiwavelength intercomparison to constrain block sizes and to distinguish surface from buried rocks in proximal ejecta deposits we find that radar detectable rocks buried within the upper meter of regolith can remain undisturbed by surface processes such as micrometeorite bombardment for 3 gyr we also investigate the thermophysical properties of radar dark haloes comprised of fine grained rock poor ejecta distal to the blocky proximal ejecta using diviner data we confirm that the halo material is depleted in surface rocks but show that it is otherwise thermophysically indistinct from background regolith we also find that radar dark haloes like the blocky ejecta remain visible in radar observations for craters with ages 3 ga indicating that regolith overturn processes cannot replenish their block populations on that timescale

global regolith thermophysical properties of the moon from the diviner lunar radiometer experiment we used infrared data from the lunar reconnaissance orbiter lro diviner lunar radiometer experiment to globally map thermophysical properties of the moon s regolith fines layer thermal conductivity varies from 7 4 10 4 w m 1 k 1 at the surface to 3 4 10 3 w m 1 k 1 at depths of 1 m given density values of 1100 kg m 3 at the surface to 1800 kg m 3 at 1 m depth on average the scale height of these profiles is 7 cm corresponding to a thermal inertia of 55 2 j m 2 k 1 s 1 2 at 273 k relevant to the diurnally active near surface layer 4 7 cm the temperature dependence of thermal conductivity and heat capacity leads to a 2x diurnal variation in thermal inertia at the equator on global scales the regolith fines are remarkably uniform implying rapid homogenization by impact gardening of this layer on timescales 100 j m 2 k 1 s 1 2 in the interiors and ejecta of copernican aged impact craters and lower thermal inertia 50 j m 2 k 1 s 1 2 within the lunar cold spots identified by bandfield et al 2014 observed trends in ejecta thermal inertia provide a potential tool for age dating craters of previously unknown age complementary to the approach suggested by ghent et al 2014 several anomalous regions are identified in the global 128 pixels per degree maps presented here including a high thermal inertia deposit near the antipode of tycho crater

the global surface temperatures of the moon as measured by the diviner lunar radiometer experiment abstract the diviner lunar radiometer experiment onboard the lunar reconnaissance orbiter lro has been acquiring solar reflectance and mid infrared radiance measurements nearly continuously since july of 2009 diviner is providing the most comprehensive view of how regoliths on airless bodies store and exchange thermal energy with the space environment approximately a quarter trillion calibrated radiance measurements of the moon acquired over 5 5 years by diviner have been compiled into a 0 5 resolution global dataset with a 0 25 h local time resolution maps generated with this dataset provide a global perspective of the surface energy balance of the moon and reveal the complex and extreme nature of the lunar surface thermal environment our achievable map resolution both spatially and temporally will continue to improve with further data acquisition daytime maximum temperatures are sensitive to the albedo of the surface and are 387 397 k at the equator dropping to 95 k just before sunrise though anomalously warm areas characterized by high rock abundances can be 50 k warmer than the zonal average nighttime temperatures an asymmetry is observed between the morning and afternoon temperatures due to the thermal inertia of the lunar regolith with the dusk terminator 30 k warmer than the dawn terminator at the equator an increase in albedo with incidence angle is required to explain the observed decrease in temperatures with latitude at incidence angles exceeding 40 topography and surface roughness influence temperatures resulting in increasing scatter in temperatures and anisothermality between diviner channels nighttime temperatures are sensitive to the thermophysical properties of the regolith high thermal inertia ti materials such as large rocks remain warmer during the long lunar night and result in anomalously warm nighttime temperatures and anisothermality in the diviner channels anomalous maximum and minimum temperatures are highlighted by subtracting the zonal mean temperatures from maps terrains can be characterized as low or high reflectance and low or high ti low maximum temperatures result from high reflectance surfaces while low minimum temperatures from low ti material conversely high maximum temperatures result from dark surface and high minimum temperatures from high ti materials impact craters are found to modify regolith properties over large distances the thermal signature of tycho is asymmetric consistent with an oblique impact coming from the west some prominent crater rays are visible in the thermal data and require material with a higher thermal inertial than nominal regolith the influence of the formation of the orientale basin on the regolith properties is observable over a substantial portion of the western hemisphere despite its age 3 8 gyr and may have contributed to mixing of highland and mare material on the southwest margin of oceanus procellarum where the gradient in radiative properties at the mare highland contact is broad 200 km

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

lunar regional dark mantle deposits geologic multispectral and modeling studies clementine five channel uv visible uvvis data have been used to study seven regional dark mantle deposits dmds on the moon the dmds were mapped in distribution to determine their extent and stratigraphic relationship to other geologic units based upon the spectral properties for each dmd the crystallization of the beads in each deposit was inferred and used to estimate cooling rates in the volcanic plumes that emplaced the deposits deposits with a high concentration of glasses reflect volcanic plumes that had low optical densities and high cooling rates whereas deposits dominated by crystallized beads indicate plumes with slower cooling rates due to higher optical densities spectral data from each of the regional dmds show that their glass crystallized bead ratio can be estimated based upon their 415 750 and 750 950 nm values and comparison to laboratory spectra for the beads patches of young dark mantle in the sinus aestuum dmd represent one extreme with the bluest color highest 415 750 and weakest glass band absorption lowest 750 950 of all the dmds at the other extreme is the aristarchus plateau dmd with the reddest color and strongest glass band absorption the other nearside dmds including taurus littrow sulpicius gallus rima bode and mare vaporum lie between these two extremes due to intermediate mixtures of the crystallized beads and glasses with other local soils the orientale ring dmd on the western limb is dominated by volcanic glasses and is spectrally similar to the localized dmds found in alphonsus crater we have identified a central vent for the orientale ring dmd and model the eruption as degassing of a near surface dike to produce a 20 km high umbrella shaped plume with ejection velocities of 360 m s and deposition of the glasses at an average radius of 80 km from the vent although we cannot identify the exact sources for the other regional dmds probably because they are buried beneath younger mare the eruptions most likely resulted from dikes breaching the surface and producing a volcanic plume dominated by larger greater than submillimeter hot clasts that formed mare and sinuous rules the small percent of clasts that form the volcanic beads are carried by the expanding gas cloud to large distances in some cases 100 km to produce the observed continuous regional dmds the lack of basalt samples that can be petrologically related to the volcanic glasses may be a result of their spatial separation with the basalts flowing into the basins while the beads are deposited both into the basins and on the adjacent highlands

using boulder tracks as a tool to understand the bearing capacity of permanently shadowed regions of the moon permanently shadowed regions psrs are abundant at the lunar poles they experience no direct sunlight and reach temperatures as low as 30 k psrs are of interest as evidence suggests that some may contain water ice h2o oh which could provide a record of the evolution of volatiles in the inner solar system this water ice is also a critical resource for life support systems and rocket propellant a better understanding of mechanical properties of psr regolith such as its bearing capacity will help optimize the design of future exploration rovers and landers thirteen boulder tracks were identified on the edge of or inside south polar lunar psr enhanced imagery and used to estimate the strength of the psr regolith at latitudes of 70 to 76 in sites with maximum annual temperatures of 65 to 210 k psr boulder track features are similar to those observed in highland mare and pyroclastic regions of the moon implying similar properties of the regolith measured features were used to estimate bearing capacity for psr regolith at depths of 0 28 to 4 68 m estimated bearing capacity values suggest that these psrs may be somewhat stronger than highland and mare regions at depths of 0 28 to 1 00 m bearing capacity in these psrs is statistically the same as those in other regions of the moon at depths of 1 00 to 2 00 m the results of this study can be used to infer bearing capacity as one measure for the trafficability of lower latitude psrs of the type measured here

earth based radar data reveal extended deposits of the moon s orientale basin we present new earth based radar observations of ejecta associated with the lunar orientale impact basin we can distinguish 1 a block poor ejecta facies composing a concentric halo of mantling material 10 m or greater in thickness that extends more than 1000 km from the basin center and 2 a melt rich deposit that forms a discontinuous but areally extensive stratigraphic marker across the southern highlands the melt rich component likely extends well into the south pole aitken basin a key target for future landed and sample return missions the observation of these two ejecta facies and their distribution across the southern nearside yields new insight into the types and distribution of material contributed by large basin forming impacts to the highlands megaregolith

the temperatures of giordano bruno crater observed by the diviner lunar radiometer experiment application of an effective field of view model for a point based data set abstract point based planetary datasets are typically stored as discrete records that represent an infinitesimal location on the target body instrumental effects and spacecraft motion during integration time can cause single points to inadequately represent the total area on the target that contributes to an observation production of mapped data products from these data for scientific analysis proceeds by binning points onto rectangular grids empty bins occur where data coverage is insufficient relative to grid resolution a common problem at high latitudes in cylindrical projections and remedial interpolation can lead to high uncertainty areas and artifacts in maps to address such issues and make better use of available data we present a method to calculate the ground projected effective field of view efov for point based datasets using knowledge of instrumental characteristics and observation geometry we apply this approach to data from the lunar reconnaissance orbiter lro diviner lunar radiometer experiment a visible to far infrared multispectral radiometer which acquires radiometric measurements of reflected visible and emitted infrared radiation of the moon in 9 spectral channels between 0 35 and 400 m analysis of gridded radiance from crater giordano bruno a 22 km diameter rayed crater is used to demonstrate our gridding procedure diviner data with such processing reveals details of the surface that are seen in the high resolution lro camera nac images brightness temperatures and anisothermality observed in diviner s ir channels show the thermophysical properties of the crater ejecta to be very heterogeneous indicative of minimal mechanical disruption by micrometeoroid impacts consistent with a very young

distal ejecta from lunar impacts extensive regions of rocky deposits abstract lunar reconnaissance orbiter lro diviner radiometer mini rf and lro camera data were used to identify and characterize rocky lunar deposits that appear well separated from any potential source crater two regions are described 1 a 18 000 km 2 area with elevated rock abundance and extensive melt ponds and veneers near the antipode of tycho crater 167 5 e 42 5 n this region has been identified previously using radar and imaging data 2 a much larger and more diffuse region covering 730 000 km 2 centered near 310 e 35 s containing elevated rock abundance and numerous granular flow deposits on crater walls the rock distributions in both regions favor certain slope azimuths over others indicating a directional component to the formation of these deposits the spatial distribution of rocks is consistent with the arrival of ejecta from the west and northwest at low angles 10 30 above the horizon in both regions the derived age and slope orientations of the deposits indicate that the deposits likely originated as ejecta from the tycho impact event despite their similar origin the deposits in the two regions show significant differences in the datasets the tycho crater antipode deposit covers a smaller area but the deposits are pervasive and appear to be dominated by impact melts by contrast the nearside deposits cover a much larger area and numerous granular flows were triggered however the features in this region are less prominent with no evidence for the presence of impact melts the two regions appear to be surface expressions of a distant impact event that can modify surfaces across wide regions resulting in a variety of surface morphologies the tycho impact event may only be the most recent manifestation of these processes which likely have played a role in the development of the regolith throughout lunar history

rays and secondary craters of tycho abstract the large fresh crater tycho in the nearside lunar highlands has an extensive system of bright rays covering approximately 560 000 km 2 containing dense clusters of secondary craters examination of crater densities in several clusters shows that tycho produced almost 10 6 secondary craters larger than 63 m diameter this is a lower limit because small crater densities are reduced most likely by mass wasting we estimate a crater erasure rate of 2 6 cm myr varying with crater size and consistent with previous results this process has removed many small craters and it is probable that the original number of secondary craters formed by tycho was higher also we can only identify distant secondaries of tycho where they occur in bright rays craters on mars and europa also formed large numbers of secondaries but under possibly ideal conditions for spallation as a mechanism to produce high velocity ejecta fragments the results from tycho show that large numbers of such fragments can be produced even from impact into a heavily fragmented target on which spallation is expected to be less important

lunar mare volcanism stratigraphy eruption conditions and the evolution of secondary crusts abstract lunar mare basalt deposits cover 17 of the lunar surface occur preferentially in topographic lows on the nearside and have a total volume estimated at 1 107 km3 analysis of returned samples and photogeologic and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment the period of cryptomare formation in pre nectarian times and continued until the copernican period a total duration approaching 3 5 4 ga stratigraphic analyses show that the flux was not constant but peaked in early lunar history during the imbrian period which spans the period 3 85 3 2 ga average volcanic output rate during this peak period was about 10 2 km 3 a very low relative to the present global terrestrial volcanic output rate and comparable to the present local output rates for individual volcanoes such as vesuvius and kilauea hawaii volcanic landforms indicate that many eruptions were of high volume and long duration some eruptions associated with sinuous rules may have lasted of the order of a year and emplaced 103 km3 of lava representing the equivalent in one year of about 70 000 years at the average flux shallow magma chambers were uncommon the nearsidefarside mare deposit asymmetry can be readily explained by differences in crustal thickness magma ascending from the mantle or from a buoyancy trap at the base of the crust should preferentially extrude to the surface on the nearside but should generally stall and cool in dikes in the farside crust extruding only in the deepest basins the occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation dikes that establish pathways to the surface on the nearside should have very high volumes comparable to the volumes associated with many observed flows and sinuous rilles an abundance of dikes should exist in the lower crust of the moon many more than those feeding surface eruptions the upper limit is 37 50 of the crust by volume the presence and abundance of such dike swarms have important implications for the interpretation of the average composition of the lunar crust and the composition of basin and crater ejecta the interplay between thermal contraction and differentiation leads to net cooling and ultimate contraction of the outer portions of the moon resulting in a regional horizontal compressive stress acting on the lunar crust in addition overall cooling and deepening of sources require the production of ever larger volumes of magma in order to reach the surface with time stresses became high enough so that few dikes could open to the surface causing eruptive activity to be severely diminished in the eratosthenian and perhaps to cease in the copernican period lower stress levels are required to terminate eruptive activity on the lunar farside consistent with the imbrian age of the farside maria and the nearside location of the youngest maria lunar mare deposits provide an example of the transition from primary crusts to secondary crusts and illustrate the significance of several factors in the evolution of secondary crusts such as crustal density variations in crustal thickness presence of impact basins state and magnitude of stress in the lithosphere and general thermal evolution these factors are also responsible for the extremely low volcanic flux even during periods of peak extrusion

lunar cold spots granular flow features and extensive insulating materials surrounding young craters abstract systematic temperature mapping and high resolution images reveal a previously unrecognized class of small fresh lunar craters these craters are distinguished by near crater deposits with evidence for lateral ground hugging transport more distal highly insulating surfaces surround these craters and do not show evidence of either significant deposition of new material or erosion of the substrate the near crater deposits can be explained by a laterally propagating granular flow created by impact in the lunar vacuum environment further from the source crater at distances of 10 100 crater radii the upper few to 10s of centimeters of regolith appear to have been fluffed up without the accumulation of significant ejecta material these properties appear to be common to all impacts but quickly degrade in the lunar space weathering environment cratering in the vacuum environment involves a previously unrecognized set of processes that leave prominent but ephemeral features on the lunar surface

highly silicic compositions on the moon using data from the diviner lunar radiometer experiment we show that four regions of the moon previously described as red spots exhibit mid infrared spectra best explained by quartz silica rich glass or alkali feldspar these lithologies are consistent with evolved rocks similar to lunar granites in the apollo samples the spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar the variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the moon basaltic underplating is the preferred mechanism for silicic magma generation leading to the formation of extrusive landforms this mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies

compositional analyses of lunar pyroclastic deposits abstract the 5 band clementine uvvis data at 100 m pixel were used to examine the compositions of 75 large and small lunar pyroclastic deposits lpds and these were compared to representative lunar maria and highlands deposits results show that the albedo spectral color and inferred composition of most lpds are similar to those of low titanium mature lunar maria these lpds may have consisted largely of fragmented basalt with substantial components of iron bearing mafic minerals pyroxenes olivine and smaller amounts if any of volcanic glass several smaller lpds also show substantial highland components three classes of very large deposits can be distinguished from most lpds and from each other on the basis of crystallinity and possible titanium content of their pyroclastic components one class has spectral properties that are dominated by high titanium crystallized black beads e g taurus littrow a second consists of a mixture of high titanium glasses and beads with a higher glass bead ratio sulpicius gallus than that of taurus littrow and a third has a significant component of quenched iron bearing volcanic glasses aristarchus with possible moderate titanium contents although areally extensive these three classes of very large pyroclastic deposits compose only 20 of the 75 deposits studied 27 and eruption of such materials was thus likely to have been less frequent on the moon

a rock model for the cold and hot spots in the chang e microwave brightness temperature map thermal anomaly spots both hot and cold have been found in the global 37 ghz brightness temperature tb map of the moon based on the chang e ce microwave radiometer measurements to explain their origin a rock model is proposed to simulate the tb variation against latitude along the profile of a fresh crater in a single track way which is selected to highlight the topographic effect and avoid any modification to the data a mixed upper layer made up of rock and soil regolith and dust was employed into our previous multilayer model the thermal properties thermal conductivity and heat capacity of the mixture layer are presumed to be linear with the fraction of rocks given that high frequency 37 ghz measurements are chosen only the meter size and larger rocks of the upper mixed layer are considered to avoid scattering effects several fresh craters poor rich in ilmenite are selected as testing sites despite uncertainties in parameters such as rock abundance ra and iron and titanium abundances three conclusions can be reached from these cases 1 ra has a significant effect on both the tb value and tb variation trend against latitude its contribution over some craters may be as high as 15 k 2 the simulations based on our rock model fit the ce observations better than those when rocks are not included and 3 the rock and ilmenite contributions could be the main cause for the cold and hot spots found in the ce microwave map

analysis of chang e 2 brightness temperature data and production of high spatial resolution microwave maps of the moon abstract the microwave radiation passively emitted from the moon is valuable for investigating the physical properties of the lunar regolith microwave maps which can reveal subsurface characteristics at depths of centimeters to meters give clues to understanding the evolution of the lunar surface china s chang e 2 ce 2 spacecraft carried a microwave radiometer mrm and conducted passive microwave remote sensing of the moon at 3 7 8 19 35 and 37 ghz 10 3 84 1 55 and 0 81 cm wavelengths during 2010 2011 brightness temperature tb data derived from the mrm orbital observations cover the entire moon and the time coverage is over a complete lunation in this paper we use spherical harmonic fits to model the tb variation as functions of local time and latitude using these fits we normalized the day and nighttime tb data measured at various local times into noon time and midnight conditions the spatial sampling of the normalized tb maps is 6 km pixel much higher than ground based observations and higher resolution than the mrm maps derived from chang e 1 by removing the variation in tb related to local time and latitude we produced a series of microwave maps that reveal differences in the properties of the regolith across the lunar surface the microwave behavior of various lunar surface features can be explained primarily by differences in the microwave loss tangent of the materials for example we find that the high ti maria have high daytime tb and exhibit lower nighttime tb than the other maria as a result of the high dielectric loss tangent of ilmenite the ilmenite rich materials are less transparent to microwaves and hence emissions emerge from closer to the surface which is heated strongly in the day and cools quickly at night most fresh craters correspond to low tb spots in the nighttime microwave maps in contrast to their behavior as hot spots in nighttime infrared data suggesting that the higher loss tangent of rocks compared to soils suppresses microwave emission at night the aristarchus plateau has a lower loss tangent relative to its surroundings because it is blanketed by fine grained rock poor pyroclastic material the pyroclastic blanket is more transparent to microwaves than the nearby maria causing the plateau to have relatively cool daytime tb and warm nighttime tb as a consequence of microwave emissions that originate at greater depths the orientale basin is another prominent anomaly in the microwave maps indicating that orientale materials differ in thermophysical and or dielectric properties from typical highland lithologies brightness temperature differences among prominent rayed craters indicate that the very youngest crater rays e g giordano bruno have lower thermal inertia than older but still optically immature rays e g tycho

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

the mairan domes silicic volcanic constructs on the moon 1 the mairan domes are four features located in northern oceanus procellarum at 312 3e 41 4n on the moon high resolution visible imagery visible to mid ir spectra and lunar prospector th abundance data all indicate that these four domes have a composition that is consistent with derivation from a si rich highly evolved magma

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

earth based observations of radar dark crater haloes on the moon implications for regolith properties 1 earth based radar can be used in conjunction with other data sets collected remotely or in situ to characterize the physical and chemical properties of the lunar regolith we use previously existing and newly acquired earth based radar measurements at 70 cm wavelength to investigate the properties of distinctive low return haloes surrounding 39 nearside impact craters these haloes are distinct from the well known optically dark haloes associated with volcanic craters or with impacts into cryptomare deposits we examine two possible mechanisms for formation of radar dark haloes 1 excavation of high tio2 high loss tangent basalt and 2 deposition of a mantling layer produced in the impact process that is depleted in meter sized blocks comparison of the radar data with apollo and lunar orbiter images indicates a general spatial correspondence between radar dark crater haloes and radial ridged ejecta facies distal to the radar bright crater rims comparison with clementine uv vis multispectral data indicates no apparent spatial correlation between regions of enhanced tio2 content and radar dark haloes though variations in tio2 content may play a role for some mare craters they are insufficient to account for the observed offsets in radar echo power we conclude that the radar dark haloes result from a block poor ejecta deposit that disappears over time with meteoroid bombardment a more detailed and comprehensive analysis of ejecta degradation processes and rates following acquisition of additional high resolution radar data could lead to a refinement of the lunar geologic timescale

near surface temperatures on mercury and the moon and the stability of polar ice deposits abstract in order to assess the thermal stability of polar ice deposits we present model calculated temperatures of flat surfaces and surfaces within bowl shaped and flat floored polar impact craters on mercury and the moon our model includes appropriate insolation cycles realistic crater shapes multiple scattering of sunlight and infrared radiation and depth and temperature dependent regolith thermophysical properties unshaded water ice deposits on the surface of either body are rapidly lost to thermal sublimation a subsurface water ice deposit is stable within 2 latitude of the moon s poles meter thick water ice deposits require billions of years to sublime if located in the permanently shaded portions of flat floored craters within 10 latitude of the poles of mercury and 13 latitude of the poles of the moon results for craters associated with radar features on mercury are consistent with the presence of stable water ice deposits if a thin regolith layer thermally insulates deposits at lower latitudes and within smaller craters a regolith cover would also reduce losses from diffusion ion sputtering impact vaporization and h ly and is implied independently by the radar observations permanently shaded areas near the moon s poles are generally colder than those near mercury s poles but the moon s obliquity history its orbit through earth s magnetospheric tail and its radar opaque regolith may limit the volume and radar detectability of ice deposits there

lunar cryptomaria physical characteristics distribution and implications for ancient volcanism cryptomaria lunar volcanic deposits obscured by crater and basin impact ejecta can provide important information about the thermal and volcanic history of the moon the timing of cryptomare deposition has implications for the duration and flux of mare basalt volcanism in addition knowing the distribution of cryptomaria can provide information about mantle convection and lunar magma ocean solidification here we use multiple datasets e g m3 lola lroc diviner to undertake a global analysis to identify the general characteristics e g topography surface roughness rock abundance albedo etc of lunar light plains in order to better distinguish between ancient volcanic deposits cryptomaria and impact basin and crater ejecta deposits we find 20 discrete regions of cryptomaria covering approximately 2 of the moon which increase the total area covered by mare volcanism to 18 of the lunar surface comparisons of light plains deposits indicate that the two deposit types volcanic and impact produced are best distinguished by mineralogic data on the basis of cryptomaria locations the distribution of mare volcanism does not appear to have changed in the time prior to its exposed mare basalt distribution there are several hypotheses explaining the distribution of mare basalts which include the influence of crustal thickness mantle convection patterns asymmetric distribution of source regions kreep distribution and the influence of a proposed procellarum impact basin the paucity of farside mare basalts means that multiple factors such as crustal thickness variations and mantle convection are likely to play a role in mare basalt emplacement

illumination conditions of the lunar polar regions using lola topography abstract we use high resolution altimetry data obtained by the lunar orbiter laser altimeter instrument onboard the lunar reconnaissance orbiter to characterize present illumination conditions in the polar regions of the moon compared to previous studies both the spatial and temporal extent of the simulations are increased significantly as well as the coverage fill ratio of the topographic maps used thanks to the 28 hz firing rate of the five beam instrument we determine the horizon elevation in a number of directions based on 240 m resolution polar digital elevation models reaching down to 75 latitude the illumination of both polar regions extending to 80 can be calculated for any geometry from those horizon longitudinal profiles we validated our modeling with recent lunar reconnaissance orbiter wide angle camera images we assessed the extent of permanently shadowed regions psrs defined as areas that never receive direct solar illumination and obtained total areas generally larger than previous studies 12 866 and 16 055 km2 in the north and south respectively we extended our direct illumination model to account for singly scattered light and found that every psr does receive some amount of scattered light during the year we conducted simulations over long periods several 18 6 years lunar precession cycles with a high temporal resolution 6 h and identified the most illuminated locations in the vicinity of both poles because of the importance of those sites for exploration and engineering considerations we characterized their illumination more precisely over the near future every year a location near the shackleton crater rim in the south polar region is sunlit continuously for 240 days and its longest continuous period in total darkness is about 1 5 days for some locations small height gains 10 m can dramatically improve their average illumination and reduce the night duration rendering some of those particularly attractive energy wise as possible sites for near continuous sources of solar power

radar mapping of lunar cryptomaria east of orientale basin 1 lunar cryptomare deposits represent early basaltic volcanic material that has been mantled by or incorporated into highland rich ejecta from basin or crater forming impacts mapping these buried basalts is important for understanding regional stratigraphy and the history and extent of lunar volcanism we use new 70 cm wavelength radar images collected using arecibo observatory and the green bank telescope and clementine data to study cryptomaria east of orientale basin earlier multispectral analyses showed that mare material is mixed with the highland terrain along the western margin of oceanus procellarum leading to a detectable increase in the feo and tio2 abundance of the regolith surface the highland margin of western procellarum is also characterized by low 70 cm radar returns consistent with an increased regolith loss tangent due to ilmenite in the mare derived material the low 70 cm radar echo however persists well to the west of the mixed zone evident in multispectral data and includes the region surrounding cruger crater it is likely that mare basalt or a mixed zone of mare and highland material exists at depth across the region and only reaches the visible surface near the western procellarum margin the plausible depth to this mixed zone is dependent upon the loss tangent of the overlying pure highland ejecta if orientale ejecta is primarily low loss anorthosite then the mixed zone could lie at depths of up to several tens of meters we propose that pre orientale mare deposits flooded the region between cruger grimaldi and oceanus procellarum and also patches west and northwest of humorum basin the total area of these deposits represents 178 103 km2 or an additional 0 5 of the lunar surface covered by mare basalts

lunar equatorial surface temperatures and regolith properties from the diviner lunar radiometer experiment 1 the diviner lunar radiometer experiment onboard the lunar reconnaissance orbiter has measured solar reflectance and mid infrared radiance globally over four diurnal cycles at unprecedented spatial and temporal resolution these data are used to infer the radiative and bulk thermophysical properties of the near surface regolith layer at all longitudes around the equator normal albedos are estimated from solar reflectance measurements normal spectral emissivities relative to the 8 m christiansen feature are computed from brightness temperatures and used along with albedos as inputs to a numerical thermal model model fits to daytime temperatures require that the albedo increase with solar incidence angle measured nighttime cooling is remarkably similar across longitude and major geologic units consistent with the scarcity of rock exposures and with the widespread presence of a near surface layer whose physical structure and thermal response are determined by pulverization through micrometeoroid impacts nighttime temperatures are best fit using a graded regolith model with a 40 increase in bulk density and an eightfold increase in thermal conductivity adjusted for temperature occurring within several centimeters of the surface

galileo imaging observations of lunar maria and related deposits the galileo spacecraft imaged parts of the western limb and far side of the moon in december 1990 ratios of 0 41 0 56 gin filter images from the solid state hnaging ssi experiment provided information on the titanium content of mare deposits ratios of the 0 76 0 99 gm images indicated 1 gin absorptions associated with fe 2 in mafic minerals mare ages were derived froin crater statistics obtained from lunar orbiter images results on mare coinpositions in western oceanus procellarum and the humorurn basin are consistent with previous earth based observations thus providing confidence in the use of galileo data to extract compositional information mare units in the grimaldi and riccioli basins range in age froin 3 25 to 3 48 ga and consist of medium to medium high titanium 4 to 7 tio2 content lavas the schiller zucchius basin shows a higher 0 76 0 99 gm ratio than the surrounding highlands indicating a potentially higher mafic mineral content consistent with previous interpretations that the area includes mare deposits blanketed by highland ejecta and light plains materials the oldest mare materials in the orientale basin occur in south central mare orientale and are 3 7 ga old youngest mare materials are in lacus autumni and are 2 85 ga old these units are medium to medium high titanium 4 to 7 tio2 basalts thus volcanism was active in orientale for 0 85 ca but lavas were relatively constant in composition galileo data suggest that mendel rydberg mare is similar to mare orientale cryptomare are present as well thus the mare lavas on the western limb and far side to 178oe are remarkably uniform in coinposition being generally of medium to medium high titanium content and having relatively low 0 76 0 99 gin ratios this region of the moon is between two postulated large impact structures the procellarum and the south pole aitken basins and may have a relatively thick crust in areas underlain by an inferred thinner crust i e zones within large basins as at apollo titanium content is often higher however no mare deposits with titanium abundances approaching those of the high titanium 9 to 14 tio2 apollo 11 and 17 basalts nor of the high titanium regions of central oceanus procellarum are seen on the western limb or eastern far side light plains deposits are generally indistinct froin the surrounding highlands in the ssi data and are inferred to be derived primarily from the same material that forins the highlands some of the light plains are too young to be related to basin forming impacts suggesting possible volcanic origin dark mantle deposit compositions derived from ssi data are consistent with earth based observations of similar near side deposits and are interpreted to be pyroclastic materials however the modernitc albedo and 1 gin absorption of the dark mantle deposit on the southwest margin of the orientale basin suggest it is a local pyroclastic deposit contaminated with underlying highland materials from the orientale impact

a comparison of rayed craters on the moon and mercury 1 observations of rayed craters at optical and radar wavelengths provide insight into the processes that lead to ray formation and degradation on terrestrial planets we have compared optical and s band radar data for several large 20 km diameter young craters on the moon and mercury and find evidence that secondary cratering plays a significant role in the formation of crater rays regions where rays appear bright to optical and radar sensors correspond to dense concentrations of secondary craters and the observed radar enhancement appears to be a result of the deposition of blocky immature ejecta from the secondary craters and or the rocky immature interior walls of the secondary craters we define a new optical maturity index for mercury and find that rays in radar and optical images correspond closely indicating that the rays are rich in centimeter to decimeter sized clasts rays on the moon are less prominent at radar wavelengths suggesting that they are currently composed of smaller clasts centimeter sized or less this difference suggests that secondary craters are larger on mercury and capable of excavating more decimeter sized clasts furthermore observations of rayed craters provide an opportunity to assign relative ages to the youngest craters on the moon and mercury although rayed craters on mercury appear most similar to the youngest craters on the moon the apparent ages are more likely influenced by inherent differences in impact velocity surface gravitational acceleration and target properties that result in the formation of larger secondary craters on mercury

global silicate mineralogy of the moon from the diviner lunar radiometer we obtained direct global measurements of the lunar surface using multispectral thermal emission mapping with the lunar reconnaissance orbiter diviner lunar radiometer experiment most lunar terrains have spectral signatures that are consistent with known lunar anorthosite and basalt compositions however the data have also revealed the presence of highly evolved silica rich lunar soils in kilometer scale and larger exposures expanded the compositional range of the anorthosites that dominate the lunar crust and shown that pristine lunar mantle is not exposed at the lunar surface at the kilometer scale together these observations provide compelling evidence that the moon is a complex body that has experienced a diverse set of igneous processes

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

lunar mare deposits associated with the orientale impact basin new insights into mineralogy history mode of emplacement and relation to orientale basin evolution from moon mineralogy mapper m3 data from chandrayaan 1 1 moon mineralogy mapper m3 image and spectral reflectance data are combined to analyze mare basalt units in and adjacent to the orientale multiring impact basin models are assessed for the relationships between basin formation and mare basalt emplacement mare basalt emplacement on the western nearside limb began prior to the orientale event as evidenced by the presence of cryptomaria the earliest post orientale event mare basalt emplacement occurred in the center of the basin mare orientale and postdated the formation of the orientale basin by about 60 100 ma over the next several hundred million years basalt patches were emplaced first along the base of the outer rook ring lacus veris and then along the base of the cordillera ring lacus autumni with some overlap in ages the latest basalt patches are as young as some of the youngest basalt deposits on the lunar nearside m3 data show several previously undetected mare patches on the southwestern margins of the basin interior regardless the previously documented increase in mare abundance from the southwest toward the northeast is still prominent we attribute this to crustal and lithospheric trends moving from the farside to the nearside with correspondingly shallower density and thermal barriers to basaltic magma ascent and eruption toward the nearside the wide range of model ages for orientale mare deposits 3 70 1 66 ga mirrors the range of nearside mare ages indicating that the small amount of mare fill in orientale is not due to early cessation of mare emplacement but rather to limited volumes of extrusion for each phase during the entire period of nearside mare basalt volcanism this suggests that nearside and farside source regions may be similar but that other factors such as thermal and crustal thickness barriers to magma ascent and eruption may be determining the abundance of surface deposits on the limbs and farside the sequence timing and elevation of mare basalt deposits suggest that regional basin related stresses exerted control on their distribution our analysis clearly shows that orientale serves as an excellent example of the early stages of the filling of impact basins with mare basalt

remote sensing studies of the terrain northwest of humorum basin we have used near infrared reflectance spectra and earth based radar data to investigate the composition and origin of the various geologic units northwest of humorum basin as well as the stratigraphy of the humorum pre impact target site the results of our spectral analysis indicate that at least a portion of the inner mare bounding ring is composed of pure anorthosite other highlands units in the region are dominated by noritic anorthosite the anorthosites on the inner ring may have been derived from a layer of anorthosite that exists at depth beneath a more pyroxene rich unit both gassendi g and f craters expose mare material from beneath a highlands rich surface unit that was emplaced as a result of the letronne gassendi and other impact events this ancient basalt unit was emplaced after the formation of humorum basin but prior to the orientale impact

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

origin of the anomalously rocky appearance of tsiolkovskiy crater abstract rock abundance maps derived from the diviner lunar radiometer instrument on the lunar reconnaissance orbiter lro show tsiolkovskiy crater to have high surface rock abundance and relatively low regolith thickness the location of the enhanced rock abundance to the southeast of the crater is consistent with a massive well preserved impact melt deposit apparent in lro miniature radio frequency instrument circular polarization ratio data a new model crater age using lro lunar reconnaissance orbiter camera imagery suggests that while it originated in the late imbrian tsiolkovskiy may be the youngest lunar crater of its size 180 km diameter together these data show that tsiolkovskiy has a unique surface rock population and regolith properties for a crater of its size and age explanation of these observations requires mechanisms that produce more large blocks preserve boulders and large blocks from degradation to regolith and or uncover buried rocks these processes have important implications for formation of regolith on the moon

geology and composition of the orientale basin impact melt sheet 1 the orientale basin is one of the largest 930 km diameter and youngest 3 8 ga impact craters on the moon as the basin is only partly flooded by mare lava its floor materials expose a major portion of the basin impact melt sheet which some previous work has suggested might have undergone igneous differentiation to test this idea we remapped the geology of the orientale basin using images and topography from the lunar reconnaissance orbiter mineralogical information from the chandrayaan 1 moon mineralogy mapper and elemental concentration maps from clementine multispectral imaging and lunar prospector gamma ray data the maunder formation impact melt sheet of the basin is uniform in chemical composition equivalent to anorthositic norite in at least the upper 2 km of the deposit the deepest sampling of the basin melt sheet maximum depths of 3 5 km by the crater maunder 55 km in diameter shows a variety of lithologies but these rock types anorthosite anorthositic norite melt rocks mare basalt and gabbro are not those predicted by the differentiation model we conclude that no differentiation of the orientale basin melt sheet has occurred and that such a process is not evident from new remote sensing data for the moon or in the apollo lunar samples

direct evidence of surface exposed water ice in the lunar polar regions water ice may be allowed to accumulate in permanently shaded regions on airless bodies in the inner solar system such as mercury the moon and ceres watson k et al 1961 j geophys res 66 3033 3045 unlike mercury and ceres direct evidence for water ice exposed at the lunar surface has remained elusive we utilize indirect lighting in regions of permanent shadow to report the detection of diagnostic near infrared absorption features of water ice in reflectance spectra acquired by the moon mineralogy mapper m 3 instrument several thousand m 3 pixels 280 280 m with signatures of water ice at the optical surface depth of less than a few millimeters are identified within 20 latitude of both poles including locations where independent measurements have suggested that water ice may be present most ice locations detected in m 3 data also exhibit lunar orbiter laser altimeter reflectance values and lyman alpha mapping project instrument uv ratio values consistent with the presence of water ice and also exhibit annual maximum temperatures below 110 k however only 3 5 of cold traps exhibit ice exposures spectral modeling shows that some ice bearing pixels may contain 30 wt ice that is intimately mixed with dry regolith the patchy distribution and low abundance of lunar surface exposed water ice might be associated with the true polar wander and impact gardening the observation of spectral features of h2o confirms that water ice is trapped and accumulates in permanently shadowed regions of the moon and in some locations it is exposed at the modern optical surface