fractal structure of lunar topography an interpretation of topographic characteristics abstract over the years fractal geometry has been applied extensively in many fields of geoscience based on the global gridded data generated from the lunar reconnaissance orbiter we carry out our fractal measure to interpret lunar fractures by using qualitative similar ratio and quantitative fractal dimension approaches of fractal geometry we find that most of the lunar surface exhibits fractal behavior over the given scales ranging from 1 to 256 m lunar maria have higher fractal dimensions than other geological units while those of volcanic areas and highlands are lower than their surroundings simple and flat surfaces have low values of similar ratios and these areas indicate low surface roughness and young ages older aged areas such as the hertzsprung basin have low fractal dimensions and high similar ratios by their complicated topography

constraint on subsurface structures beneath reiner gamma on the moon using the kaguya lunar radar sounder abstract reiner gamma is a sinuous feature in oceanus procellarum it has a higher reflectance of the visible wavelength than the surrounding flat mare basalt and displays a high crustal magnetic field previous studies relating to the origin of reiner gamma have provided contradictory depths of magnetic source bodies in the lunar crust as either shallow or deep if a shallow ejecta layer existed beneath the reiner gamma formation a subsurface lithological boundary between the denser mare basalt and the less dense ejecta blanket would be expected this study examines subsurface stratifications using the lunar radar sounder lrs onboard the kaguya spacecraft taking into account the lrs determined dielectric constants the influence of surface clutter and the energy loss of the lrs radar pulses in the high frequency band 5 mhz no evidence was found of subsurface boundaries down to a depth of 1000 m at reiner gamma given the lrs range resolution of 75 m the source of the magnetic anomaly is considered to be either strongly magnetized thin breccia layers at depths shallower than 75 m or less magnetized thick layers at depths deeper than 1000 m

summary of the results from the lunar orbiter laser altimeter after seven years in lunar orbit in june 2009 the lunar reconnaissance orbiter lro spacecraft was launched to the moon the payload consists of 7 science instruments selected to characterize sites for future robotic and human missions among them the lunar orbiter laser altimeter lola was designed to obtain altimetry surface roughness and reflectance measurements the primary phase of lunar exploration lasted one year following a 3 month commissioning phase on completion of its exploration objectives the lro mission transitioned to a science mission after 7 years in lunar orbit the lola instrument continues to map the lunar surface the lola dataset is one of the foundational datasets acquired by the various lro instruments lola provided a high accuracy global geodetic reference frame to which past present and future lunar observations can be referenced it also obtained high resolution and accurate global topography that were used to determine regions in permanent shadow at the lunar poles lola further contributed to the study of polar volatiles through its unique measurement of surface brightness at zero phase which revealed anomalies in several polar craters that may indicate the presence of water ice in this paper we describe the many lola accomplishments to date and its contribution to lunar and planetary science

the nature of crater rays the copernicus example crater rays are formed during a cratering event as target material is ballistically ejected to distances of many crater radii forming narrow generally high albedo approximately linear features extending outward from the crater the nature of crater rays was examined for the lunar crater copernicus using new information on the composition of surface material from near ir reflectance measurements surface roughness from radar backscatter measurements and photogeologic data from available images part of the data analysis included use of mixing models to quantify the mixing systematics observed between primary ejecta and local substrate of the ray on the basis of compositional parameters from reflectance spectra primary material from copernicus can be detected in the surface material of rays in decreasing amounts with increasing radial distance e g 20 25 primary ejecta at six crater radii for distances greater than three crater radii the proportion of local material to primary ejecta observed from these compositional reflectance data is approximately equal to that predicted by previous laboratory and ballistic studies of craters within three crater radii the compositional data indicate a higher proportion of primary ejecta than predicted for extended areas along the ray that do not contain large secondary craters the primary ejecta is intimately mixed on the granular scale with local material throughout the regolith the relatively high albedo of the rays of copernicus is due to the feldspathic composition highland of the primary ejecta in rays emplaced on a mare substrate immature local substrate is only observed in copernicus s ray at large unmantied secondary craters or other areas with sufficient topographic slope to prevent the accumulation of mature soils crater rays are filamentous generally high albedo features that emanate nearly radially from young impact structures rays are narrow in relation to the crater radius extend distally for many crater radii and constitute a distinctive albedo feature around some of the largest and freshest lunar craters visible from earth synoptic views of ray systems figure la give the strong impression that the rays comprise bright material that has been excavated from the crater cavity and been emplaced beyond the continuous ejecta deposit if this visual impression is correct then the process that forms crater rays represents a significant mechanism for the lateral transport of primary material to great distances from its point of origin and particularly for craters larger than a let tens of kilometers in diameter constitutes a fundamental process for the regional mixing of crustal materials earth based telescopic images of the moon allowed the first studies and descriptions of rays and ray systems shoemaker 1962 described the arcuate and loop shaped streaks of the copernicus ray systems and showed that these patterns could be locally resolved into individual en echelon feather shaped elements 15 20 km in length with their long axes oriented approximately radially to the crater he noted the presence of elongate depressions or gouges in the ray system ranking in diameter from 8 km down to the limits of resolution and generally located at the proximal ends of the individual ray elements shoemaker observed that some of the gouges were

roughness of hawaiian volcanic terrains 1 we performed analyses of topographic variation surface roughness using a new 2 d mapping method which shows that understanding the relationship between data resolution hurst exponent y intercept rms deviation and cell size is important for assessing surface processes we use this new method to assess flows at six field sites in kilauea caldera hawaii using three data sets at different resolutions topsar 10 m pixel airborne lidar 1 m pixel and tripod mounted lidar 0 02 0 03 m pixel the flows studied include ponded pahoehoe flows compound pahoehoe flows and jumbled slabby pahoehoe the 2 d quantification of surface roughness for the kilauea lava flows indicates that features formed during emplacement and modification of the flows exhibit statistically distinct roughness signatures the 2 d method provides a tool for unit mapping based on surface roughness key findings indicate that the new 2 d method provides more robust results than 1 d methods for surface roughness because of larger 2 d sample sizes and the removal of 1 d directional bias leading to a reduction in error furthermore data set resolution relative to the scale of the features under study is important to consider when designing a 2 d surface roughness study future applications to topographic data sets from mars will provide information on flow emplacement conditions and spatial and temporal evolution of volcanic provinces on mars

maximum likelihood estimation of lithospheric flexural rigidity initial loading fraction and load correlation under isotropy topography and gravity are geophysical fields whose joint statistical structure derives from interface loading processes modulated by the underlying mechanics of isostatic and flexural compensation in the shallow lithosphere under this dual statistical mechanistic viewpoint an estimation problem can be formulated where the knowns are topography and gravity and the principal unknown the elastic flexural rigidity of the lithosphere in the guise of an equivalent effective elastic thickness this important geographically varying structural parameter has been the subject of many interpretative studies but precisely how well it is known or how best it can be found from the data abundant nonetheless has remained contentious and unresolved throughout the last few decades of dedicated study the popular methods whereby admittance or coherence both spectral measures of the relation between gravity and topography are inverted for the flexural rigidity have revealed themselves to have insufficient power to independently constrain both it and the additional unknown initial loading fraction and load correlation fac tors respectively solving this extremely ill posed inversion problem leads to non uniqueness and is further complicated by practical considerations such as the choice of regularizing data tapers to render the analysis sufficiently selective both in the spatial and spectral domains here we rewrite the problem in a form amenable to maximum likelihood estimation theory which we show yields unbiased minimum variance estimates of flexural rigidity initial loading frac tion and load correlation each of those separably resolved with little a posteriori correlation between their estimates we are also able to separately characterize the isotropic spectral shape of the initial loading processes

new observational evidence of global seismic effects of basin forming impacts on the moon from lunar reconnaissance orbiter lunar orbiter laser altimeter data 1 new maps of kilometer scale topographic roughness and concavity of the moon reveal a very distinctive roughness signature of the proximal ejecta deposits of the orientale basin the hevelius formation no other lunar impact basin even the just preceding imbrium basin is characterized by this type of signature although most have similar types of ejecta units and secondary crater structures the preservation of this distinctive signature and its lack in basins formed prior to orientale is interpreted to be the result of seismically induced smoothing caused by this latest major basin forming event intense seismic waves accompanying the orientale basin forming event preceded the emplacement of its ejecta in time and operated to shake and smooth steep and rough topography associated with earlier basin deposits such as imbrium orientale ejecta emplaced immediately following the passage of the seismic waves formed the distinctive roughness signature that has been preserved for almost 4 billion years

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

seamount statistics in the pacific ocean we apply the wide beam sampling technique of jordan et al 1983 to approximately 157 000 km of wide beam profiles to obtain seamount population statistics for eight regions in the eastern and southern pacific ocean population statistics derived from wide beam echograms are compared with seamount counts from sea beam swaths and with counts from bathymetric maps we find that the average number of seamounts with summit heights h h is well approximated by the exponential frequency size distribution h oe h the exponential model for seamount sizes characterized by the single scale parameter 1 is found to be superior to a power law self similar model which has no intrinsic scale in describing the average distribution of pacific seamounts and it appears to be valid over a size spectrum spanning 5 orders of magnitude in abundance large scale regional variations in seamount populations are documented we observe significant differences in seamount densities across the murray fracture zone in the north pacific and the eltanin fracture zone system in the south pacific the eltanin discontinuity is equally evident on both sides of the pacific antarctic ridge in the south pacific regions symmetrically disposed about the ridge axis have very similar seamount densities despite the large difference between pacific plate and antarctic plate absolute velocities evidently any differences in the shear flows at the base of the pacific and antarctic plates do not affect seamount emplacement systematic variations in o and are observed as a function of lithospheric age with the number of large seamounts increasing more rapidly than small seamounts these observations have been used to develop a simple model for seamount production under the assumptions that 1 an exponential size frequency distribution is maintained 2 production is steady state and 3 most small seamounts are formed on or near the ridge axis the limited data available from this study appear to be consistent with the model but they are insufficient to provide a rigorous test of the assumptions or determine accurately the model parameters however the data from the south pacific indicate that the off axis production of large seamounts probably accounts for the majority of seamounts with summit heights greater than 1000 m

the global surface roughness of 433 eros from the near laser rangefinder abstract we performed the first global surface roughness assessment of the asteroid 433 eros at baselines horizontal distances of 4 200 m we measured surface roughness using the root mean square rms deviation over a variety of baselines after first detrending the height to remove long wavelength slope effects the global surface roughness of eros is found to be self affine at all baselines investigated the surface roughness is statistically correlated with crater density at baselines of 100 200 m and boulders at a baseline of 5 m no global spatial statistical correlation was found for baselines of 4 200 and mapped tectonic lineaments ponds slope or geopotential elevation the surface roughness of the crater shoemaker charlois regio is controlled by the interplay of a high boulder density producing higher surface roughness values at small baselines and low crater density lowering surface roughness values at long baselines we estimated the mobile regolith thickness regolith that moves around and infills topography to be 0 2 6 2 m from the difference in the surface roughness values at the baseline of 4 m furthermore we find that the change in rms deviation as a function of baseline compares favorably with the moon and differs significantly from existing results for rubble pile asteroid itokawa

lunar topographic roughness maps from lunar orbiter laser altimeter lola data scale dependence and correlation with geologic features and units we present maps of the topographic roughness of the moon at hectometer and kilometer scales the maps are derived from range profiles obtained by the lunar orbiter laser altimeter lola instrument onboard the lunar reconnaissance orbiter lro spacecraft as roughness measures we used the interquartile range of profile curvature at several baselines from 115 m to 1 8 km and plotted these in a global map format the maps provide a synoptic overview of variations of typical topographic textures and utilize the exceptional ranging precision of the lola instrument we found that hectometer scale roughness poorly correlates with kilometer scale roughness because they reflect different sets of processes and time scales hectometer scale roughness is controlled by regolith accumulation and modification processes and affected by the most recent events primarily geologically recent 1 2 ga meteoritic impacts kilometer scale roughness reflects major geological impact volcanic and tectonic events in earlier geological history young large impact craters are rough and their roughness decreases with age the global roughness maps revealed a few unusually dense clusters of hectometer and decameter size impact craters that differ in their morphology and settings from typical secondary crater clusters and chains the origin of these features is enigmatic the maps can assist in the geological mapping of the lunar maria by revealing contacts between volcanic plain units the global roughness maps also clearly reveal cryptomaria old volcanic plains superposed by younger materials primarily crater and basin ejecta

gld100 the near global lunar 100 m raster dtm from lroc wac stereo image data 1 we derived near global lunar topography from stereo image data acquired by the wide angle camera wac of the lunar reconnaissance orbiter camera lroc system from polar orbit tracks the lroc wac provides image data with a mean ground resolution at nadir of 75 m pixel with substantial cross track stereo overlap wac stereo images from the one year nominal mission and the first months of the science mission phase are combined to produce a near global digital terrain model dtm with a pixel spacing of 100 m the global lunar dtm 100 m or gld100 it covers 79 s to 79 n latitudes 98 2 of the entire lunar surface we compare the gld100 with results from previous stereo and altimetry based products particularly with the lunar orbiter laser altimeter lola altimetry which is the current topographic reference for the moon we describe typical characteristics of the gld100 and based upon the comparison to the lola data set assess its vertical and lateral resolution and accuracy we conclude that the introduced first version of the stereo based gld100 is a valuable topographic representation of the lunar surface complementary to the lola altimetry data set further improvements can be expected from continuative investigations

resolved hapke parameter maps of the moon we derived spatially resolved near global hapke photometric parameter maps of the moon from 21 months of lunar reconnaissance orbiter camera lroc wide angle camera wac multispectral observations using a novel tile by tile method 1 latitude by 1 longitude bins the derived six parameters w b c bs0 hs and p for each tile were used to normalize the observed reflectance standard angles i g 60 e 0 instead of the traditional angles i g 30 e 0 within each tile resulting in accurate normalization optimized for the local photometric response each pixel in the seven color near global mosaic 70 s to 70 n and 0 e to 360 e was computed by the median of normalized reflectance from large numbers of repeated observations uv 50 and visible 126 on average the derived mosaic exhibits no significant artifacts with latitude or along the tile boundaries demonstrating the quality of the normalization procedure the derived hapke parameter maps reveal regional photometric response variations across the lunar surface the b c henyey greenstein double lobed phase function parameters maps demonstrate decreased backscattering in the maria relative to the highlands except 321 nm band probably due to the higher content of both smfe submicron iron and ilmenite in the interiors of back scattering agglutinates in the maria the hs angular width of shadow hiding opposition effect map exhibits relatively lower values in the maria than the highlands and slightly higher values for immature highland crater ejecta possibly related to the variation in a grain size distribution of regolith

paleoproterozoic 1 90 1 86 ga arc volcanism in the flin flon belt trans hudson orogen canada geochemical and isotopic nd sr data are reported on paleoproterozoic 1904 1864 ma maficintermediate 1870 ma collision and subsequent intra arc deformation

the roughness of natural terrain a planetary and remote sensing perspective we examine the various methods and parameters in common use for quantifying and reporting surface topographic roughness it is shown that scale dependent roughness parameters are almost always required though not widely used we suggest a method of standardizing the parameters that are computed and reported so that topographic data gathered by different workers using different field techniques can be directly and easily intercompared we illustrate the proposed method by analyzing topographic data from 60 different surfaces gathered by five different groups and examine the information for common features we briefly discuss the implications of our analysis for studies of planetary surface roughness lander safety and radar remote sensing modeling and analysis

self affine behavior of martian topography at kilometer scale from mars orbiter laser altimeter data 1 we used mars orbiter laser altimeter mola data from the current mars global surveyor mission to characterize the topographic roughness of the martian surface and to provide a mean to evaluate clutter at long 10 300 m wavelengths such wavelengths are relevant for the marsis and sharad subsurface radars which will be flown in future missions to mars the method of analysis is based on the assumption that topography can be described as a self affine fractal 30 km long segments of mola altimetry profiles have thus been reduced to the topographic parameters rms height rms slope and hurst exponent this last related to the fractal dimension which can be used as inputs to a near nadir radar scattering model the values of the hurst exponent are greater than 0 5 for most of the surface meaning a scaling behavior which is almost self similar maps of rms height and hurst exponent show that these two parameters have very different spatial distributions whereas the rms height is patterned after the north south dichotomy the hurst exponent follows a latitudinal trend we make use of a multivariate method called g mode to classify profiles in the three dimensional parameter space we find several roughness units some of which have a strong correlation with certain geologic units while others are bound by latitude however at scales between 300 m and 3 km large stretches of the surface of mars share common statistical properties of topography independent from the north south dichotomy

ages and stratigraphy of lunar mare basalts in mare frigoris and other nearside maria based on crater size frequency distribution measurements 1 we report on ages derived from impact crater counts for exposed mare basalt units in the northern part of the lunar nearside hemisphere mare frigoris the eastern and northeastern part of the nearside hemisphere lacus temporis joliot hubble goddard mare marginis and mare smythii the central part of the nearside hemisphere palus putredinis mare vaporum and sinus medii and the southwestern part of the nearside hemisphere grimaldi cruger rocca a lacus aestatis and schickard in mare frigoris we dated 37 basalt units showing ages from 2 61 to 3 77 gyr with most units being formed in the late imbrian period between 3 4 and 3 8 gyr ago in mare vaporum we dated six spectrally homogeneous units that show model ages of 3 10 to 3 61 gyr our model ages of basalts in mare marginis range from 3 38 to 3 88 gyr and are mostly older than basalts in mare smythii 3 14 3 48 gyr the model ages of four units in sinus medii indicate that the basalts in this region formed 3 63 to 3 79 gyr ago we find an excellent agreement of our crater size frequency model ages of the palus putredinis area which contains the apollo 15 landing site with the radiometric ages of apollo 15 samples according to our crater counts basalts in palus putredinis are 3 34 gyr old and this compares favorably with the radiometric ages of 3 30 3 35 gyr of the olivine normative and quartz normative basalts of the apollo 15 landing site lacus aestatis is a small irregular shaped mare patch in the southwestern nearside and shows an imbrian age of 3 50 gyr basalts in lacus temporis in the northeastern nearside formed between 3 62 and 3 74 gyr ago and are therefore older than the basalts in lacus aestatis we found that basalts in craters of the southwestern nearside schickard grimaldi cruger and rocca a are also mostly younger than basalts in craters of the northeastern nearside hubble joliot and goddard while basalt ages vary between 3 16 and 3 75 gyr in the southwest basalts in the northeast are 3 60 3 79 gyr old these results confirm and extend the general distribution of ages of mare basalt volcanism and further underline the predominance of older mare basalt ages in the eastern and southern nearside and in patches of mare peripheral to the larger maria in contrast to the younger basalt ages on the western nearside oceanus procellarum

circular polarization ratio characteristics of impact craters from mini rf observations and implications for ice detection at the polar regions of the moon 1 in an attempt to reduce the ambiguity on radar detection of water ice at the permanently shadowed regions near the lunar poles radar echo strength and circular polarization ratio cpr of impact craters are analyzed using the miniature radio frequency mini rf radar data from the lunar reconnaissance orbiter mission eight typical craters among over 70 craters are selected and classified into four categories based on their locations and cpr characteristics polar anomalous polar fresh nonpolar anomalous and nonpolar fresh the influences on cpr caused by surface slope rocks and dielectric constant are analyzed quantitatively using high resolution topography data and optical images a two component mixed model for cpr that consists of a normal surface and a rocky surface is developed to study the effect of rocks that are perched on lunar surface and buried in regolith our analyses show that inner wall of a typical bowl shaped crater can give rise to a change of about 30 in local incidence angle of radar wave which can further result in a cpr difference of about 0 2 there is a strong correlation between mini rf cpr and rock abundance that is obtained from high resolution optical images and predictions from the two component mixed model match well with the observed cprs and the estimated rock abundances statistical results show that there is almost no apparent difference in cpr characteristics between the polar and nonpolar anomalous craters or between the polar and nonpolar fresh craters the enhanced cpr in the interior of anomalous craters is most probably caused by rocks that are perched on lunar surface or buried in regolith instead of ice deposits as suggested in previous studies

the steepest slopes on the moon from lunar orbiter laser altimeter lola data spatial distribution and correlation with geologic features abstract we calculated topographic gradients over the surface of the moon at a 25 m baseline using data obtained by the lunar orbiter laser altimeter lola instrument onboard the lunar reconnaissance orbiter lro spacecraft the relative spatial distribution of steep slopes can be reliably obtained although some technical characteristics of the lola dataset preclude statistical studies of slope orientation the derived slope frequency distribution revealed a steep rollover for slopes close to the angle of repose slopes significantly steeper than the angle of repose are almost absent on the moon due to 1 the general absence of cohesion strength of the fractured and fragmented megaregolith of the lunar highlands and 2 the absence of geological processes producing steep slopes in the recent geological past the majority of slopes steeper than 32 35 are associated with relatively young large impact craters we demonstrate that these impact craters progressively lose their steepest slopes we also found that features of early imbrian and older ages have almost no slopes steeper than 35 we interpret this to be due to removal of all steep slopes by the latest basin forming impact orientale probably by global seismic shaking the global spatial distribution of the steepest slopes correlates moderately well with the predicted spatial distribution of impact rate however a significant paucity of steep slopes in the southern farside remains unexplained

synthetic aperture radar processing of kaguya lunar radar sounder data for lunar subsurface imaging synthetic aperture radar sar processing was applied to the observation data of lunar radar sounder lrs which is an hf sounder which was installed onboard a japanese lunar exploration orbiter kaguya for the purpose of imaging lunar subsurface structure a two media model was introduced to the lrs sar algorithm to define the reference function of the lrs sar processing the lrs sar algorithm has two free parameters i e dielectric constant of the subsurface medium and synthetic aperture the effect of these free parameters on lrs sar imaging was studied by simulation and was verified by actual lrs observation data a practical guideline for lrs sar processing was drawn the dielectric constant of the subsurface medium may be ignored in practice so far as the synthetic aperture is smaller than 10 km for a larger synthetic aperture case assumption of a moderate dielectric constant e 6 8 of the subsurface medium is effective in realizing good focusing of deep targets finally taking full advantage of ground processing advanced processing was attempted off nadir focusing sar processing proved to be effective in imaging oblique objects whose dominant scattering angle was not the angle toward zenith changing the dielectric constant of the two media model proved to be effective in focusing defocusing small objects thus enabling us to localize the object s position as surface or subsurface

the timing and magnitude of mountain glaciation in the tropical andes the andes of ecuador peru and bolivia host the majority of the world s tropical glaciers in the tropical andes glaciers accumulate during the wet season austral summer and ablate year round precipitation is delivered mainly by easterlies and decreases both n s and e w chronological control for the timing of glacial advances in the tropical andes varies in ecuador six to seven advances have been identified dating is based on radiocarbon ages timing of the local last glacial maximum lgm and the existence of younger dryas advances remain controversial in peru local variability in glaciation patterns is apparent surface exposure dating in the cordillera blanca and junin plain suggests that the local lgm may have been early 30 ka although uncertainties in age calculations remain the local lgm was followed by a lateglacial readvance stillstand and preceded by larger glaciations in contrast preliminary data from an intervening massif indicate that the largest moraines are lateglacial chronologies from bolivia also suggest local variability in leeward milluni and san francisco valleys local lgm moraines descend to 4300 m above sea level a s l whereas in windward zongo valley lateglacial moraines reach 3400 m a s l atlantic and pacific sea surface temperatures el nino southern oscillation and insolation changes all likely play roles in mediating tropical andean glacial cycles copyright 2008 john wiley sons ltd additional supporting information may be found in the online version of this article

the surface roughness of mercury from the mercury laser altimeter investigating the effects of volcanism tectonism and impact cratering surface roughness is a statistical measure of change in surface height over a given spatial horizontal scale after the effect of broad scale slope has been removed and can be used to understand how geologic processes produce and modify a planet s topographic character at different scales the statistical measure of surface roughness employed in this study of mercury was the root mean square rms deviation and was calculated from 45 90 n at horizontal baselines of 0 5 250 km with detrended topographic data from individual mercury laser altimeter tracks as seen in previous studies the surface roughness of mercury has a bimodal spatial distribution with the cratered terrain dominated by the intercrater plains possessing higher surface roughness than the smooth plains the measured surface roughness for both geologic units is controlled by a trade off between impact craters generating higher surface roughness values and flood mode volcanism decreasing surface roughness the topography of the two terrain types has self affine like behavior at baselines from 0 5 1 5 km the smooth plains collectively have a hurst exponent of 0 88 0 01 whereas the cratered terrains have a hurst exponent of 0 95 0 01 subtle variations in the surface roughness of the smooth plains can be attributed to differences in regional differences in the spatial density of tectonic landforms the northern rise a 1 000 km wide region of elevated topography centered at 65 n 40 e is not distinguishable in surface roughness measurements over baselines of 0 5 250 km

crater degradation on the lunar maria topographic diffusion and the rate of erosion on the moon landscape evolution on the moon is dominated by impact cratering in the post maria period in this study we mapped 800 m to 5 km diameter craters on 30 of the lunar maria and extracted their topographic profiles from digital terrain models created using the kaguya terrain camera we then characterized the degradation of these craters using a topographic diffusion model because craters have a well understood initial morphometry these data provide insight into erosion on the moon and the topographic diffusivity of the lunar surface as a function of time the average diffusivity we calculate over the past 3 ga is 5 5 m2 myr with this diffusivity after 3 ga a 1 km diameter crater is reduced to approximately 52 of its initial depth and a 300 m diameter crater is reduced to only 7 of its initial depth and craters smaller than 200 300 m are degraded beyond recognition our results also allow estimation of the age of individual craters on the basis of their degradation state provide a constraint on the age of mare units and enable modeling of how lunar terrain evolves as a function of its topography

measuring multiresolution surface roughness using v system surface roughness is a land surface parameter that is widely used in terrain analysis some typical roughness details which have important effects on surface analysis fail to be characterized on previous roughness maps the objective of this paper is to provide a more accurate small to large scale roughness overview the new roughness method is designed based on a complete orthogonal system called the v system the v system roughness utilizes the special functions to detect and extract the roughness characteristics from high resolution digital elevation models dems in this paper lunar orbiter laser altimeter derived dems are used as the source data for the roughness calculation compared with the global root mean square slope and fourier based roughness maps the v system roughness maps show that more typical roughness details have been added to clearly indicate the small roughness variations on the large map furthermore the reliability and practicability of v system roughness are demonstrated based on the multiresolution dems as an example the statistical parameters of the roughness characteristics in the lunar maria and highlands identify the fact that the highlands are rougher at all scales than the maria and this difference corresponds to the basic roughness property

elliptical structure of the lunar south pole aitken basin abstract the south pole aitken basin sp a is the largest and oldest basin on the moon the basin has usually been interpreted to exhibit a degraded circular structure but here we demonstrate that the topography iron and thorium signatures of the basin are well described by ellipses with axes measuring 2400 by 2050 km and centered at 53 191 e topography abundances of iron thorium and the distribution of mare basalts are all elevated in the northern halves of the ellipses we also identify an outer topographic ellipse whose semiminor axis scales with the main topographic ellipse by approximately 2 taken together these data imply that the basin was created by an oblique impact along an azimuth of approximately 19 measured counterclockwise from longitude 191 e the geometry of the elevated central farside topography surrounding sp a suggests that it predates the impact the elliptical ring structures of sp a and their scaling relationships will help to understand the formation of large and elliptical basins elsewhere in the solar system this refined basin shape will also inform local geology geochemistry and geophysics of the region

lidar derived surface roughness texture mapping application to mount st helens pumice plain deposit analysis statistical measures of patterns textures in surface roughness are used to quantitatively differentiate volcanic deposit facies on the pumice plain on the northern flank of mount st helens msh surface roughness values are derived from a light detection and ranging lidar point cloud collected in 2004 from a fixed wing airborne platform patterns in surface roughness are characterized using co occurrence texture statistics pristine pyroclastic reworked pyroclastic mudflow boulder beds eroded lava flows braided streams and other units within the pumice plain are all found to have significantly distinct roughness textures the msh deposits are reasonably accessible and the textural variations have been verified in the field results of this work indicate that by affecting the distribution of large clasts and tens of meter scale landforms modification of pyroclastic deposits by lahars alters the morphology of the surface in detectable quantifiable ways when a lahar erodes a pyroclastic deposit surface roughness increases as does the randomness in the deposit surface conversely when a lahar deposits material the resulting landforms are less rough but more random than pristine pumice rich pyroclastic deposits by mapping these relationships and others volcanic deposit facies can be differentiated this new method of mapping based on roughness texture has the potential to aid mapping efforts in more remote regions both on this planet and elsewhere in the solar system

thermal stability of ice on ceres with rough topography the dwarf planet ceres may have an ice rich crust and subsurface ice exposed by impacts or endogenic activity would be subject to sublimation we model surface and subsurface temperatures on ceres to assess lifetimes of water ice and other volatiles topographic shadowing allows a small but non negligible fraction 0 4 of ceres surface to be perennially below the 110 k criterion for 1 gyr of stability these areas are found above 60 latitude other molecules ch3oh nh3 so2 co2 may be cold trapped in smaller abundances a model for the transport gravitational escape and photoionization of h2o molecules suggests net accumulation in the cold traps buried ice is stable within a meter for 1 gyr at latitudes higher than 50 an illuminated polar cap of water ice would be stable within a few degrees of the poles only if it maintained a high albedo 0 5 at present obliquity if the obliquity exceeded 5 in the geologically recent past then a putative polar cap would have been erased at latitudes 0 30 ice is stable under solar illumination only briefly 10 100 yr unless it has high albedo and thermal inertia in which case lifetimes of 104 yr are possible finally a small hemispheric asymmetry exists due to the timing of ceres perihelion passage which would lead to a detectable enhancement of ice in the northern hemisphere if the orbital elements vary slowly relative to the ice accumulation rate our model results are potentially testable during the dawn science mission

ring moat dome structures rmdss in the lunar maria statistical compositional and morphological characterization and assessment of theories of origin ring moat dome structures rmdss are positive morphologic features found clustered across many mare regions on the moon of which only a few isolated examples have been previously reported our continuing survey has expanded the known locations of the rmdss from 2 600 to over 8 000 indicating that rmdss are more common geological features than previously thought this work presents a detailed geomorphological analysis of 532 rmdss identified in several mare basins the combination of detailed elemental mapping morphological and morphometric analyses spatial distribution relationships with other geologic structures and comparison with terrestrial analogs lead us to conclude that 1 rmdss represent low circular mounds with diameters of a few hundred meters average about 200 m and a mean height of 3 5 m the mounds are surrounded by moats ranging from tens to over 100 m in width and up to several meters in depth 2 there is a wide variation of titanium abundances although rmdss are more commonly found in mare regions of moderate to high titanium content 3 wt tio2 3 rmdss are found to occur on or around fractures graben and volcanic edifices small shields and cones 4 a spatial association between rmdss and irregular mare patches see braden et al 2014 https doi org 10 1038 ngeo2252 is observed suggesting that both may form from related lava flows 5 comparisons between rmdss and lava inflationary structures on earth support an inflation related extrusive nature and a genetic relationship with host lava flow processes and 6 rmds embayment relationships with craters of different degradation ages superposed on the host mare and regolith development models produces conflicting age relationships and divide theories of rmds origin into two categories 1 synchronous with the emplacement and cooling of the host lava flows 3 4 ga and 2 emplaced substantially after the host mare lava unit in the period 0 3 ga we outline the evidence supporting this age conundrum and implications for the different theories of origin and describe future research avenues to help resolve these outstanding questions 2020 american geophysical union all rights reserved

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

analysis of regional slope characteristics on venus and earth regional slope values for earth and venus are calculated for each 3 o x 3 o region of topography and the global characteristics of these magnitudes are examined and compared the effects on terrestrial regional slope due to ocean loading are treated by approximating the component of seafloor depth due to the weight of the overlying water column and removing this component from the ocean topography although regional slopes on venus and earth span the same range 0 00 2 4 o 0 07o the slope frequency distributions for the two planets differ significantly the most abundant regional slope values for the terrestrial cases earth and unloaded earth are 0 0 o and reflect the presence of vast plains associated with the continental interiors and ocean abyssal plain in contrast venus exhibits a peak in slope frequency at approximately 0 09 o perhaps indicating less effective planation processes in the absence of a hydrosphere surfaces with regional slope values of 0 07o 0 24 o are substantially more common on venus than on earth slopes in this range are associated with discrete features in the lowland and upland rolling plains provinces of venus and may be indicative of a geologic process that is not commonly observed on earth only 14 1 of all venus surfaces have regional slopes above 0 24 o compared to 26 1 for earth when mean regional slope is calculated as a function of elevation a distinctive positive correlation is expressed on venus in contrast the terrestrial cases exhibit a complex relationship marked by four modes related to the presence on earth of an active hydrosphere driven weathering regime a distinctive crustal dichotomy and plate tectonics the distinctions in the regional slope characteristics between venus and earth point to a simpler less diversified geology on venus

a theoretical model for the formation of ring moat dome structures products of second boiling in lunar basaltic lava flows abstract newly documented ring moat dome structures rmdss low mounds typically several hundred meters across with a median height of 3 5 m and surrounded by moats occur in the lunar maria they appear to have formed synchronously with the surrounding mare basalt deposits it has been hypothesized that they formed on the surfaces of lava flows by the extrusion of magmatic foams generated in the flow interiors as the last stage of the eruption and flow emplacement process we develop a theoretical model for the emplacement and cooling of mare basalts in which the molten cores of cooling flows are inflated during the late stages of eruptions by injection of additional hot lava containing dissolved volatiles crystallization of this lava causes second boiling an increase in vapor pressure to the point of supersaturation due to crystallization of the melt generating copious quantities of vesicles magmatic foam layers at the top and bottom of the central core of the flow flow inflation of many meters is predicted to accompany the formation of the foam layers flexing the cooled upper crustal layer and forming fractures that permit extrusions of the magmatic foams onto the surface to form domes with subsidence of the subjacent and surrounding surface forming the moats by modeling the evolution of the internal flow structure we predict the properties of rmdss and the conditions in which they are most likely to form we outline several tests of this hypothesis

multifractal topography of several planetary bodies in the solar system abstract topography is the expression of both internal and external processes of a planetary body thus hypsometry the study of topography is a way to decipher the dynamics of a planet for that purpose the statistics of height and slopes may be described by different tools at local and global scale we propose here to use the multifractalapproach to describe fields of topography this theory encompasses height and slopes and other statistical moments of the field taking into account the scale invariance contrary to the widely used fractalformalism multifractals are able to describe the intermittency of the topography field as we commonly observe a juxtaposition of rough and smooth topographies at a given scale the multifractal framework seems to be appropriate for hypsometric studies here we analyze the data at global scale of the earth mars mercury and the moon and find that the statistics are in good agreement with the multifractaltheory for scale larger than 10 km surprisingly the analysis shows that all bodies have the same fractal behavior for scale smaller than 10 km we hypothesize that dynamic topography of the mantle may be the explanation at large scale whereas the smaller scale behavior may be related to elastic thickness

subsurface ice on mars with rough topography high latitude ground ice on mars discovered by the gamma ray spectrometer suite is thought to be thermally stable owing to the presence of vapor in the martian atmosphere however local slopes can alter surface and subsurface temperatures substantially and hence allow ground ice to persist at locations where it would otherwise be unstable global statistics of the topography of mars are computed processed and extrapolated to derive a description of surface roughness on spatial scales to which ground ice should be sensitive this slope distribution is convolved with a new thermal model for the dependence of subsurface ice on slope to produce a prediction of the global ice distribution that includes the effect of topographic roughness in the highest latitudes slopes reduce the amount of buried ice while in lower latitudes the ice fraction increases widening the geographic boundary of the ice table at the high latitudes where ice is stable beneath horizontal ground the estimated reduction of ice is small compared to the existing ice volume areas in the midlatitudes with high surface roughness that have previously been predicted to be ice free are predicted to contain quantities of ice that may be detectable at present and accessible in the future slopes cause ground ice to be stable to latitudes of about 25 degrees in both hemispheres including for example areas within the northern olympus mons aureole deposits hecates tholus and hellas basin ice is unstable at equatorial latitudes even when accounting for surface slopes

the surface roughness of europa derived from galileo stereo images abstract we assess the surface roughness of europa by reevaluating galileo stereo images roughness provides important information about surface textures which are related to geologic processes operating at a variety of scales roughness also sets important performance requirements for various remote sensing instruments on board the upcoming icy satellite missions to the jovian system in this study roughness is derived for different geologic terrains on europa which have been distinguished through geomorphological mapping for each terrain type we derive the scale dependent root mean square roughness and corresponding hurst exponents we investigate the scale between 30 m and 5 km and show that europa s surface can mostly be described by a monofractal behavior over these baselines i e surface roughness follows power laws with breakpoints located at a few hundred meters hurst exponents are higher below the breakpoints with typical values between 0 4 and 0 8 and lower above typically between 0 2 and 0 6 this behavior is mostly controlled by ridges which are dominating the topography on europa at unity scale 1 m roughness is extrapolated to be around 0 4 0 7 m with strong exceptions on chaos terrain where values over 1 2 m can be achieved assuming that no further breakpoints are present below the resolution of the digital terrain models used in this study

optimized traverse planning for future polar prospectors based on lunar topography abstract to fully understand the extensive collection of remotely sensed polar observations by the lunar reconnaissance orbiter and other recent lunar missions we must acquire an array of ground truth measurements a polar rover can sample and assay potential polar resources both laterally and at shallow depths to identify ideal least energy traverses for such a polar prospecting mission we developed a traverse planning tool called r traverse using a fundamental wheel regolith interaction model and datasets from the lunar reconnaissance orbiter camera lunar orbiter laser altimeter and diviner lunar radiometer experiment using the terramechanics model we identified least energy traverses at the 20 m scale around shackleton crater and located one traverse plan that enables the rover to remain illuminated for 94 4 of the lunar year by incorporating this path planning tool during mission planning the feasibility of such a mission can be quantified

extracting accurate and precise topography from lroc narrow angle camera stereo observations abstract the lunar reconnaissance orbiter camera lroc includes two identical narrow angle cameras nac that each provide 0 5 to 2 0 m scale images of the lunar surface although not designed as a stereo system lroc can acquire nac stereo observations over two or more orbits using at least one off nadir slew digital terrain models dtms are generated from sets of stereo images and registered to profiles from the lunar orbiter laser altimeter lola to improve absolute accuracy with current processing methods dtms have absolute accuracies better than the uncertainties of the lola profiles and relative vertical and horizontal precisions less than the pixel scale of the dtms 2 5 m we computed slope statistics from 81 highland and 31 mare dtms across a range of baselines for a baseline of 15 m the highland mean slope parameters are median 9 1 mean 11 0 standard deviation 7 0 for the mare the mean slope parameters are median 3 5 mean 4 9 standard deviation 4 5 the slope values for the highland terrain are steeper than previously reported likely due to a bias in targeting of the nac dtms toward higher relief features in the highland terrain overlapping dtms of single stereo sets were also combined to form larger area dtm mosaics that enable detailed characterization of large geomorphic features from one dtm mosaic we mapped a large viscous flow related to the orientale basin ejecta and estimated its thickness and volume to exceed 300 m and 500 km 3 respectively despite its 3 8 billion year age the flow still exhibits unconfined margin slopes above 30 in some cases exceeding the angle of repose consistent with deposition of material rich in impact melt we show that the nac stereo pairs and derived dtms represent an invaluable tool for science and exploration purposes at this date about 2 of the lunar surface is imaged in high resolution stereo and continued acquisition of stereo observations will serve to strengthen our knowledge of the moon and geologic processes that occur across all of the terrestrial planets

the relationship between radar scattering and surface roughness of lunar volcanic features lunar roughness measurements derived from the lunar orbiter laser altimeter are compared to 12 6 cm wavelength radar data collected by the miniature radio frequency instrument and 70 cm wavelength radar data collected by the arecibo observatory these data are compared to assess how surface and subsurface roughness are correlated and affected by parameters including age and composition at length scales between 0 1 and 100 m a range of features are analyzed including volcanic domes marius hills rumker hills gruithuisen and mairan domes mare imbrium serenitatis and oceanus procellarum pyroclastic dark mantle deposits sinus aestuum sulpicius gallus and mare vaporum and two young craters copernicus and tycho statistically significant positive correlations exist between topographic roughness and both p and s band circular polarization ratios the strongest correlation is observed at the longest length scales correlations weaken as length scales become less similar potentially due to distinct processes controlling surface modification roughness is not significantly correlated with local slope although the marius hills are compositionally distinct from the gruithuisen and mairan domes they are indistinguishable in roughness characteristics conversely the rumker hills mare and dark mantle deposits are smoother at the length scales examined possibly due to fine grained mantling of regolith or pyroclastic deposits the floor and ejecta of tycho are the roughest surfaces measured in this study while the floor and ejecta of copernicus overlap the roughness distribution of the volcanic features this study shows that many factors control the evolution of roughness over time on various length scales

statistics of mars topography from the mars orbiter laser altimeter slopes correlations and physical models data obtained recently by the mars orbiter laser altimeter mola were used to study the statistical properties of the topography and slopes on mars we find that the hemispheric dichotomy manifested as an elevation difference can be described by long baseline tilts but in places is expressed as steeper slopes the bimodal hypsometry of elevations on mars becomes unimodal when referenced to the center of figure contrary to the earth for which the bimodality is retained however ruling out a model in which the elevation difference is expressed in a narrow equatorial topographic step cannot be done by the hypsometry alone mars slope distribution is longer tailed than those of earth and venus indicating a lower efficiency of planation processes relative to relief building tectonics and volcanics we define and compute global maps of statistical estimators including the interquartile scale rms and median slope and characteristic decorrelation length of the surface a correspondence between these parameters and geologic units on mars is inferred surface smoothness is distinctive in the vast northern hemisphere plains where slopes are typically 0 5 amazonis planitia exhibits a variation in topography of 1 m over 35 km baselines the region of hematite mineralization in sinus meridiani is also smooth with median slopes lower than 0 4 but does not form a closed basin the shallower long wavelength portion of the lowlands topographic power spectrum relative to the highlands can be accounted for by a simple model of sedimentation such as might be expected at an ocean s floor the addition of another process such as cratering is necessary to explain the spectral slope in short wavelengths among their application these mola derived roughness measurements can help characterize sites for landing missions

deriving terrain factors from high resolution lunar images a case study of the mons rumker region abstract mons rumker is a preferred candidate landing region for china s chang e 5 ce 5 mission from where it is of great significance to select safe landing areas lunar terrain factors from digital elevation model dem data limited by their low resolutions 10 m pixel are inapplicable to evaluating the lunar landing area safety in spite of the fact that lunar remote sensing imagery has higher resolution 50 cm pixel in this paper we extracted terrain factors in divided square girds by the aid of the high resolution lunar reconnaissance orbiter lro narrow angle camera nac images namely flat area percentage fap distribution pattern of uneven objects nni based on the double threshold otsu method and roughness based on gray level histogram analysis mons rumker can be divided into four geological units named as ld b1 b2 and b3 respectively unit b1 has a higher roughness and a lower fap unit b2 and b3 are characterized with the highest fap and the lowest roughness nnis of unit b1 b2 and b3 are 1 while ld s is

kilometer scale roughness of mars results from mola data analysis the mars orbiter laser altimeter mola data are used to characterize the kilometer scale surface roughness of mars the median absolute value of the differential slope at a given baseline is proposed as a data derived measure of the surface roughness at this scale study of the scale dependence of roughness for the smoothest terrains gives an independent estimate of 20 cm for mola ranging accuracy the baseline lengths from 0 6 to 20 km are used and kilometer scale roughness is mapped for the entire surface the maps show that different geological units have distinctive roughness characteristics scale dependence of roughness for a number of geological units is presented and discussed the southern polar cap is rougher than the northern at kilometer and subkilometer scale which suggests differences in the sublimation condensation balance the vastitas borealis formation has a distinctive 3 km scale background surface topography which suggests a nonvolcanic origin for its upper layer young volcanic plains in amazonis planitia and the eastern part of elysium planitia are very similar to each other in their roughness characteristics and differ from other volcanic plains on mars which suggests a distinctive eruption style there are systematic latitudinal variations of roughness in both the southern highlands and the northern lowlands terrains at high latitude are smoother at short baselines the characteristic vertical scale related to this difference is several meters processes that could be responsible for formation of this trend include creep of ice rich near surface material at high latitudes treatment of the surface with repetitive deposition and sublimation of seasonal frost climate controlled deposition and or cementation of dust at high latitudes and repetitive sublimation and accumulation of subsurface ice at low latitudes with climate variations all mechanisms of origin could operate more effectively under different climate conditions relevant morphological observations favor mechanisms involving deposition of smooth blankets at high latitudes

surface roughness retrieval by inversion of the hapke model a multiscale approach abstract surface roughness is a key property of soils that controls many surface processes and influences the scattering of incident electromagnetic waves at a wide range of scales hapke 2012b designed a photometric model providing an approximate analytical solution of the bidirectional reflectance distribution function brdf of a particulate medium he introduced the effect of surface roughness as a correction factor of the brdf of a smooth surface this photometric roughness is defined as the mean slope angle of the facets composing the surface integrated over all scales from the grain size to the local topography yet its physical meaning is still a question at issue as the scale at which it occurs is not clearly defined this work aims at better understanding the relative influence of roughness scales on soil brdf and to test the ability of the hapke model to retrieve a roughness that depicts effectively the ground truth we apply a wavelet transform on millimeter digital terrain models dtm acquired over volcanic terrains this method allows splitting the frequency band of a signal in several sub bands each corresponding to a spatial scale we demonstrate that sub centimeter surface features dominate both the integrated roughness and the brdf shape we investigate the suitability of the hapke model for surface roughness retrieval by inversion on optical data a global sensitivity analysis of the model shows that soil brdf is very sensitive to surface roughness nearly as much as the single scattering albedo according to the phase angle but also that these two parameters are strongly correlated based on these results a simplified two parameter model depending on surface albedo and roughness is proposed inversion of this model on brdf data simulated by a ray tracing code over natural targets shows a good estimation of surface roughness when the assumptions of the model are verified with a priori knowledge on surface albedo

one slope or two detecting statistically significant breaks of slope in geophysical data with application to fracture scaling relationships the scaling of displacement as a function of length is important for a variety of applications which depend on the mechanical and hydraulic properties of faults and fractures recently it has been suggested that the power law exponent which has been found to characterise this relationship may change significantly at a characteristic length for a variety of reasons for example when cracks begin to interact or when faults grow to a length comparable to a characteristic size in the brittle layer such a break of slope requires a second straight line requiring two extra model parameters here we present a new method for analysing such data which penalises the extra parameters using a modified form of schwarz s information criterion and a bayesian approach which represents uncertainty in the unknown parameters we apply the method to data from the krafla fissure zone in the north of iceland and find a significant break of slope from 3 2 to 2 3 at a characteristic length of 12m

characterization of the morphometry of impact craters hosting polar deposits in mercury s north polar region 1 earth based radar images of mercury show radar bright material inside impact craters near the planet s poles a previous study indicated that the polar deposit hosting craters pdcs at mercury s north pole are shallower than craters that lack such deposits we use data acquired by the mercury laser altimeter on the messenger spacecraft during 11 months of orbital observations to revisit the depths of craters at high northern latitudes on mercury we measured the depth and diameter of 537 craters located poleward of 45 n evaluated the slopes of the northern and southern walls of 30 pdcs and assessed the floor roughness of 94 craters including nine pdcs we find that the pdcs appear to have a fresher crater morphology than the non pdcs and that the radar bright material has no detectable influence on crater depths wall slopes or floor roughness the statistical similarity of crater depth diameter relations for the pdc and non pdc populations places an upper limit on the thickness of the radar bright material 170 m for a crater 11 km in diameter that can be refined by future detailed analysis results of the current study are consistent with the view that the radar bright material constitutes a relatively thin layer emplaced preferentially in comparatively young craters

the lunar reconnaissance orbiter mission six years of science and exploration at the moon abstract since entering lunar orbit on june 23 2009 the lunar reconnaissance orbiter lro has made comprehensive measurements of the moon and its environment the seven lro instruments use a variety of primarily remote sensing techniques to obtain a unique set of observations these measurements provide new information regarding the physical properties of the lunar surface the lunar environment and the location of volatiles and other resources scientific interpretation of these observations improves our understanding of the geologic history of the moon its current state and what its history can tell us about the evolution of the solar system scientific results from lro observations overturned existing paradigms and deepened our appreciation of the complex nature of our nearest neighbor this paper summarizes the capabilities measurements and some of the science and exploration results of the first six years of the lro mission

geology and scientific significance of the rumker region in northern oceanus procellarum china s chang e 5 landing region the rumker region 41 45 n 49 69 w is located in northern oceanus procellarum of the moon mons rumker is the most distinctive geological feature in the area the region is characterized by prolonged lunar volcanism late imbrian period to eratosthenian period forming multiple geologic units in the area including very low ti to low ti mare basalts high ti mare basalts and volcanic complexes each geologic unit has distinct element composition and mineral assemblages the rumker region overlying the procellarum kreep terrain was selected as the landing region for china s chang e 5 lunar sample return mission prelanding analyses of the geologic context and scientific potential are reported in this contribution we conducted detailed geological mapping using image spectral and altimetry data fourteen geological units were defined a geologic map was constructed and the geologic history was outlined the western mare units im1 im2 and im3 are imbrian aged 3 4 3 5 ga representing the major stage of lunar mare eruptive volcanism the eastern young mare units em3 and em4 2 ga are among the youngest mare basalts on the moon they have never been explored in situ or studied in the laboratory we suggest that samples returned from the eastern mare unit em4 could answer many fundamental questions and that this unit should be listed as the top priority landing site for chang e 5 sample return mission

dating small fresh lunar craters with mini rf radar observations of ejecta blankets 1 the ages of large impact craters on the moon can be estimated by measuring the size frequency distribution of smaller craters superimposed on their ejecta but applying this method to individual craters under 3 km in diameter remains difficult due to their limited areal extent the ejecta blankets of fresh lunar impact craters are expressed as halos of optical and radar bright material that gradually fade with time although compositional differences make inferring crater ages from optical albedo problematic radar is less sensitive to composition and thus may provide a more reliable means of estimating age in this work we use radar data from the miniature radio frequency mini rf instrument on the lunar reconnaissance orbiter lro to characterize the radar backscatter of large numbers of ejecta blankets by analyzing the size frequency distribution of these craters we show that the lifetime of the radar bright discontinuous ejecta blanket varies with crater diameter in a predictable way for craters with diameters between 0 45 and 5 km absolute ages of individual craters can then be estimated by combining this empirically derived model with estimates of the relative degradation state of each individual crater the lifetimes of radar bright discontinuous ejecta blankets are significantly shorter in the highlands than the maria although this is likely due to local topography creating difficulties in applying the method to the highlands the cosmic ray exposure age of south ray crater a fresh crater visited by apollo 16 provides confirmation of these results this method therefore provides a new way to accurately date small fresh craters using the mini rf data set

global surface slopes and roughness of the moon from the lunar orbiter laser altimeter 1 the acquisition of new global elevation data from the lunar orbiter laser altimeter carried on the lunar reconnaissance orbiter permits quantification of the surface roughness properties of the moon at unprecedented scales and resolution we map lunar surface roughness using a range of parameters median absolute slope both directional along track and bidirectional in two dimensions median differential slope and hurst exponent over baselines ranging from 17 m to 2 7 km we find that the lunar highlands and the mare plains show vastly different roughness properties with subtler variations within mare and highlands most of the surface exhibits fractal like behavior with a single or two different hurst exponents over the given baseline range when a transition exists it typically occurs near the 1 km baseline indicating a significant characteristic spatial scale for competing surface processes the hurst exponent is high within the lunar highlands with a median value of 0 95 and lower in the maria with a median value of 0 76 the median differential slope is a powerful tool for discriminating between roughness units and is useful in characterizing among other things the ejecta surrounding large basins particularly orientale as well as the ray systems surrounding young copernican age craters in addition it allows a quantitative exploration on mare surfaces of the evolution of surface roughness with age

the global surface roughness of 25143 itokawa abstract surface roughness is an important metric in understanding how the geologic history of an asteroid affects its small scale topography and it provides an additional means to quantitatively compare one asteroid with another in this study we report the first detailed global surface roughness maps of 25143 itokawa at horizontal scales from 8 32 m comparison of the spatial distribution of the surface roughness of itokawa with 433 eros the other asteroid for which this kind of analysis has been possible indicates that the two asteroids are dominated by different geologic processes on itokawa the surface roughness reflects the results of down slope activity that moves fine grained material into geopotential lows and leaves large blocks in geopotential highs on 433 eros the surface roughness is controlled by geologically recent large impact craters in addition large longitudinal spatial variations of surface roughness could impact the role of yorp on itokawa