Lunar Surface Material Research Articles

Low‐temperature thermal and physical properties of lunar meteorites

AbstractLunar meteorites are the most diverse and readily available specimens for the direct laboratory study of lunar surface materials. In addition to informing us about the composition and heterogeneity of lunar material, measurements of their thermo‐physical properties provide data necessary to inform the models of the thermal evolution of the lunar surface and provide data on fundamental physical properties of the surface material for the design of exploration and resource extraction hardware. Low‐temperature data are particularly important for the exploration of low‐temperature environments of the lunar poles and permanently shadowed regions. We report low‐temperature‐specific heat capacity, thermal conductivity, and linear thermal expansion for six lunar meteorites: Northwest Africa [NWA] 5000, NWA 6950, NWA 8687, NWA 10678, NWA 11421, and NWA 11474, over the range 5 ≤ T ≤ 300 K. From these, we calculate thermal inertia and thermal diffusivity as functions of temperature. Additionally, heat capacities were measured for 15 other lunar meteorites, from which we calculate their Debye temperature and effective molar mass.

Isotopic variations of Sm, Gd, Er and Yb found in planetary materials caused by neutron-capture reactions in nature

The isotopic shifts of 149Sm–150Sm and 157Gd–158Gd have often been observed in meteorites and lunar surface materials, because they result from the neutron-capture reactions associated with secondary neutrons produced by cosmic-ray irradiation. While the Sm and Gd isotopic shifts can mainly be used for the estimation of thermal neutron fluences that of 167Er–168Er has recently been applied in the estimation of epithermal neutron fluences. The systematic isotopic dataset of Sm, Gd and Er helps us to consider the details of planetary materials’ cosmic-ray exposure conditions using the balance of the fluences between thermal and epithermal neutrons. This paper reviews a series of isotopic variations of Sm, Gd, and Er in association with neutron-capture reactions for the application of planetary sciences. As a new attempt and possibility for better understanding the neutron fluence and its energy distribution, the use of Yb isotopic variation is then discussed using two different data sources, namely lunar regolith and the Oklo natural reactors. Finally, the preliminary result for the precise isotopic measurement of Yb is presented from the viewpoint of chemical separation and instrumental improvement.

In-situ mapping of iron and titanium with the visible and near-infrared image spectrometer (VNIS) along the Yutu-2 rover traverse on the farside of the moon

In January 2019, China's Chang'E-4 probe successfully landed in the Von Kármán crater of the Moon's farside's South Pole-Aitken basin. Till August 2021, the Yutu-2 rover had worked for >32 lunar days. The Visible and Near-infrared Image Spectrometer (VNIS) is one of scientific payloads on board the rover that can collect in-situ spectral data. This provides a unique perspective for investigating the composition of the lunar surface materials. In this work, a local-scale FeO and TiO2 abundance mapping approach based on the in-situ VNIS data was proposed to utilize the fine spectral-spatial hyperspectral information. Improved FeO and TiO2 abundance inversion models were performed on each unshaded pixel to generate abundance maps. Experimental results obtained on 115 VNIS observation data along the Yutu-2's routing path confirm the effectiveness of the proposed approach, especially in the complex observation scenarios. Comparing with the in-orbit data products and the in-situ abundance results obtained by the reference methods, the effectiveness of the proposed in-situ FeO and TiO2 abundance mapping approach is validated. Furthermore, the proposed approach allows a detailed analysis of chemical properties and spatial distribution of lunar surface materials, and helps to discover abnormal targets according to the serial spectral observations along the rover's routing path, which reveals the great potential in more precise lunar surface material identification and analysis applications.

Effects of space weathering on the Christiansen feature position of lunar surface materials

We use observations by the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment to examine the effects of space weathering and particle size on the position of the Christiansen feature (CF) in thermal infrared (TIR) spectra of silicate lithologies on the Moon. Laboratory studies have found that both the increased surface iron content associated with formation of nanophase iron (npFe) during space weathering and decreasing grain size of regolith shift the CF position to longer wavelengths for TIR spectra measured under lunar-like conditions. This study confirms that the variation in CF position due to space weathering measured in the laboratory, is also evident at orbital scales. We have used swirls and rayed craters from lunar highlands and mare regions to examine the effect of initial composition and particle size distribution on the change of CF position. We also examine the effect of magnetic shielding at lunar swirls on the CF position. Our observations indicate that 1) for quantitatively comparable changes in albedo, the CF shift is greater for mare surfaces than for highlands surfaces; 2) particle-size is the dominant factor for the CF shift in fine-particulate regolith;3) npFe accumulation dominates CF position changes in coarser regolith and 4) the variation in CF position of lunar swirls is positively correlated to the magnetic field strength in the region. We hypothesize that the effects of particle size variations are also observed between the crater and swirl regions. However, further work is needed to constrain the effective particle size distributions of the regolith.

Orbital Characterization of the Composition and Distribution of Spinels Across the Crisium Region: Insight From Luna 20 Samples

AbstractSpinels represent a small fraction of lunar surface materials but provide important insights into the petrological evolution of the lunar crust and mantle. Previous remote sensing analyses of highlands spinel‐bearing lithologies have focused on pure Mg‐Al spinels, which are rare in the lunar sample collection. Using Moon Mineralogy Mapper data, we develop and test an approach for detecting spectral signatures of spinel across a wider range of Mg, Al, Fe, Cr, Ti‐bearing compositions than have been addressed in previous studies, including within mafic‐bearing assemblages. This approach is validated through integration with laboratory‐measured spinel spectra and petrographic observations of samples returned by the Luna 20 mission from the Hilly and Furrowed Terrain surrounding the Crisium Basin. Applying this approach to data from the Crisium region, small abundances of spinel (<∼5 vol%) with a range of Mg, Al, Fe, Cr, and Ti content and petrologic origin (inferred from Luna 20 samples) were found to be widespread within highlands soils across the Crisium region. This result diverges from previous remote sensing analyses, which only reported small, isolated exposures of pure Mg‐Al spinel (as well as a possible detection of Fe, Cr‐bearing spinels localized within pyroclastic materials at Sinus Aestuum). Geologic associations of candidate spinel detections across this region are consistent with a shallow crustal origin rather than excavation from depth during the Crisium‐forming impact. These spinels are detectible in near‐infrared spectroscopic data, particularly in areas of low optical maturity and may influence the spectral continuum of highlands soils.

Moon’s Two Faces: Near-Side/Far-Side Maria Disparity

Any attempt to understand the origin of lunar maria must as well account for the dearth of maria on the far-side of the Moon. Various attempts have been made to explain the origin of lunar maria based solely upon obvious lunar processes, namely, volcanism and impact phenomena. Here I review a different explanation for the origin of lunar maria by analogy with observations of Earth, specifically related to its central nuclear fission georeactor. Georeactor formation is a natural consequence of density layering in oxygen-starved (highly-reduced) planetary matter and is ideally suited for magnetic field generation in planets and large moons. A portion of georeactor produced heat is channeled to Earth’s surface hot-spots, e.g., Hawaii and Iceland, where its georeactor origin is indicated by the high relative 3He/4He ratios observed, and seismically imaged heat channels extending to the top of the core. Massive basalt floods, e.g., Deccan and Siberian Traps were driven by georeactor-produced heat as indicated by the high relative 3He/4He ratios of their occluded helium. These terrestrial basalt floods suggest to me that the lunar maria might have similar origins driven by the Moon’s nuclear fission “lunar-reactor.” Remanent magnetization of some lunar surface material is indicative of an ancient internally-generated magnetic field. That implication is consistent with the magnetic fields produced by central nuclear fission reactors in many planets and large moons. The location of the lunar-reactor at the Moon’s center of mass, displaced 2 km toward the Earth-facing side, in concert with Earth’s tidal pull, I posit, is principally responsible for driving the maria-basalt floods toward the Earth facing side of the Moon. In principle, it should be possible to verify the correctness of this concept by measuring the helium isotopes of maria basalt samples taken from depths sufficient to be unaffected by solar wind implanted helium.

Overview of the dielectric permittivity of lunar surface materials and implications for Chang’E-5 samplemeasurements

<p indent="0mm">The dielectric permittivity of lunar surface materials determines the penetration depth of electromagnetic waves in the lunar subsurface; hence, it is crucial to the design of scientific payloads such as radars, microwave radiometers, and lunar surface electromagnetic experiments. Additionally, dielectric permittivity is a key parameter in deciphering radar and microwave radiometer observations, which is important to obtain quantitative information regarding the subsurface structure and physical properties of the Moon. Our current knowledge of the dielectric permittivity of lunar surface materials depends mainly on the inversion of microwave remote sensing data and laboratory measurements of the Apollo and Luna samples. In December 2020, China’s Chang’E-5 mission successfully collected <sc>1.731 kg</sc> of lunar samples from the northern Oceanus Procellarum, thus providing new samples for studying the dielectric properties of lunar materials. In this paper, I will first introduce the basic knowledge of dielectric permittivity, including the dielectric polarization mechanism, dielectric permittivity mixing model, and measurement methods. Then, I will summarize the history and present status of the research on the dielectric permittivity of lunar materials and demonstrate the dielectric permittivity of the Moon. Finally, I will present the latest research results of the geological background and regolith properties of the Chang’E-5 landing region and provide some suggestions regarding the laboratory measurements and potential scientific outcome of the Chang’E-5 lunar samples. The summarization of our current knowledge of the dielectric permittivity of lunar regolith in this paper can provide theoretical guidance and engineering support for microwave sensor design, radar data interpretation, sampling site selection, and sample analysis for China’s future lunar exploration missions.

Lunar Surface Temperature and Emissivity Retrieval From SDGSAT-1 Thermal Imager Spectrometer

The lunar surface temperature is one of the important thermophysical parameters of the Moon, which helps to study the radiative properties of the lunar surface. Thermal infrared emission spectra is sensitive to the thermophysical properties of the lunar surface material, and the emissivity data can be used for lunar surface composition inversion. In the past, humans have conducted hundreds of lunar exploration missions, but only a small number have been conducted in the infrared band, typical examples include the Apollo program and the Diviner lunar radiometer experiment of the LRO satellite. Only part of the lunar surface has been explored by these missions. SDGSAT-1 carries out a complete observation of the lunar surface in three infrared wavelength bands (B1: 8-10.5μm; B2: 10.3-11.3μm; B3: 11.5-12.5μm) by its thermal imager as part of its mission. In this study, the temperature-emissivity separation (TES) algorithm is used to retrieve the lunar surface temperature and calculate the thermal infrared band emissivity using the radiometric data obtained by SDGSAT-1 thermal imager, the temperature distribution of full-disk Moon and the emissivities distribution of three bands are also mapped. The temperature retrieval error is verified less than 1K.

A Raman spectroscopy–compositional–structural investigation of lunar surface materials and analogues

AbstractWe investigated the Raman spectroscopy of 35 rock and mineral samples of composition relevant to the lunar surface: pyroxenes, olivine, plagioclase feldspars and oxides. The Raman spectra were analysed in the context of their compositional and structural properties to develop robust correlations to enable their detection on the lunar surface by Raman spectroscopy. We developed and implemented a spectral deconvolution program to model the fluorescence background and various Raman peaks to extract their positions in wavenumber space. Relations were developed between the Raman peak positions of pyroxenes around 325, 670 and 1000 cm−1 with their compositions in terms of enstatite, ferrosilite and wollastonite components. For olivines, we verified previously determined correlations between the positions of the olivine‐related peak doublet between 800 and 880 cm−1 with forsterite content. We also discuss the main signatures detected in the Raman spectra of plagioclases and oxides. The derived relationships were examined using Raman spectra of the matrix and several inclusions of the lunar meteorite NWA12593. We were able to identify the main endmembers of the selected surface spots as pyroxenes, plagioclase feldspars and olivine. We used the previous correlations to separate orthopyroxene from clinopyroxene signatures and to propose a composition of the inclusions of the meteorite. The results of this study demonstrate the utility of Raman spectroscopy for determining the mineralogy of the lunar surface.

Working with lunar surface materials: Review and analysis of dust mitigation and regolith conveyance technologies

The Moon's dusty surface environment threatens any equipment that operates there, especially for long-duration infrastructure needed for a sustained lunar presence. This is doubly true for systems that convey regolith, which by agitating the soil are certain to generate dust. Here, we provide a comprehensive review of technologies that have been proposed to convey regolith on the lunar surface, and to mitigate against dust hazards that are generated by such transport systems. We define functional taxonomies for both regolith conveyance and dust mitigation, then carry out quantitative trade studies in several categories for each. Examples include passive and active dust mitigation, and horizontal and near vertical conveyance. Conveyance technologies that scored particularly high include wheeled haulers, conveyor belts, and auger/hopper transfer points. High scoring dust mitigation technologies include the lotus leaf passive coating, Electrodynamic Dust Shield, and boots or bellow made of fiberglass fabric. We also explore novel or unconventional concepts and describe how dust mitigation and regolith conveyance can be combined using a systems approach with multiple technologies layered together. The results from the trade studies and the subsequent recommendations constitute a practical guide that can be used for designing and developing systems that must perform efficiently and reliably to carry out useful tasks on the Moon or Mars, such as resource extraction, construction, and additive manufacturing.

An improved method combining Fisher transformation and multiple endmember spectral mixture analysis for lunar mineral abundance quantification using spectral data

Mineral abundance quantification of lunar surface materials using remotely acquired spectra can be achieved with spectral unmixing methods, but this has remained a challenging problem. The existing unmixing methods neglect the existence of widespread glass material and the spectral similarity of different minerals. To solve this problem, this study proposes a method to calculate the main mineral abundances in lunar regolith based on reflectance spectra by utilizing Fisher transformation combined with multiple endmember spectral mixture analysis (MESMA). A set of spectra of lunar main constituents, including plagioclase, pyroxene, ilmenite, olivine and glass material, were selected from the RELAB spectral database and used as endmembers. The endmember spectra were utilized to compute the projection vectors, with which the spectral characteristics can be transformed into low-dimensional Fisher space in which intraclass spectral variability can be minimized while the interclass variability of different mineral spectra can be maximized. The endmember spectra and the lunar soil spectra in the Lunar Soil Characterization Consortium (LSCC) dataset were both transformed into Fisher space, in which MESMA was executed to acquire the fraction of each endmember. MESMA allows for comprehensive endmember expressions by representing a type of mineral using multiple spectra rather than a single endmember. Compared with laboratory mineral measurements, this approach estimated the mineral abundances with determination coefficient R2 values equal to 0.88 and 0.65 in the lunar mare and highland regions, respectively. After validation with laboratory data, the method was further applied at the regional scale where Apollo 12 and Apollo 16 landed by using M3 images, and the estimated accuracy of different minerals was similar to that of the laboratory spectra.

The gardening process of lunar regolith by small impact craters: A case study in Chang'E-4 landing area

On January 3, 2019, Chang'E-4 (CE-4) probe successfully achieved soft landing on the farside of the Moon. A large number of small craters in the landing area can be found in the high-resolution remote sensing images. These small craters played a vital role in the evolution of lunar regolith because of the overturning and mixing of lunar surface material through excavating and ejecting during impact processes. However, the research of the gardening process by small craters and the evolution of farside lunar regolith are still insufficient. This research aims to make quantitative analysis to the evolution of the lunar regolith from regional small impacts and apply them in the CE-4 landing area. Firstly, the processes of excavation and ejection of a single small impact on the lunar surface are analyzed, during which the formation and distribution of lunar regolith are numerically modeled. Then, based on the remote sensing observation and the analysis of regional impact flux, a group of impact events with resulting lunar regolith are modeled by Monte Carlo method. Thirdly, the above analysis is applied in the CE-4 landing area, and the thickness, grain size distribution, and overturning times of the lunar regolith are calculated. Finally, the influencing factors are discussed and evolution process of lunar regolith is summarized. The results indicate that the formation of lunar regolith is controlled by larger impact events, while the surficial overturning and mixing of lunar regolith are mainly caused by smaller impact events. In addition, the lunar regolith is mostly formed in the earlier times because of the high impact flux at that time. For example, the absolute model age of the CE-4 landing area is about 3.5 Ga, while the lunar regolith had mostly been formed before 3.0 Ga and changed slowly afterwards. Our model beyond the observational capability of the Yutu-2's lunar penetrating radar (LPR), and the results can contribute to better understanding of the regional lunar regolith formation and evolution.

New Explanation for the Near-Side/Far-Side Lunar Maria Disparity

Any attempt to understand the origin of lunar maria must as well account for the dearth of maria on the far-side of the Moon. Various attempts have been made to explain the origin of lunar maria based solely upon obvious lunar processes, namely, volcanism and impact phenomena. Here I posit a different explanation for the origin of lunar maria by analogy with observations of Earth, specifically related to its central nuclear fission georeactor. Georeactor formation is a natural consequence of density layering in oxygen-starved (highly-reduced) planetary matter and is ideally suited for magnetic field generation in planets and large moons. A portion of georeactor produced heat is channeled to Earth’s surface hot-spots, e.g., Hawaii and Iceland, where its georeactor origin is indicated by the high relative 3He/4He ratios observed and seismically imaged heat channels extending to the top of the core. Massive basalt floods, e.g., Siberian and Deccan Traps were driven by georeactor-produced heat as indicated by the high relative 3He/4He ratios of their occluded helium. These terrestrial basalt floods suggest to me that the lunar maria might have similar origins driven by the Moon’s nuclear fission “lunar-reactor.” Remanent magnetization of some lunar surface material is indicative of an ancient internally-generated magnetic field. That implication is consistent with the magnetic fields produced by central nuclear fission reactors in many planets and large moons. The location of the lunar-reactor at the Moon’s center of mass, displaced 2 km toward the Earth-facing side, in concert with Earth’s tidal pull, I posit, is principally responsible for driving the maria-basalt floods toward the Earth facing side of the Moon. In principle, it should be possible to verify the correctness of this concept by measuring the helium isotopes of maria basalt samples taken from depths sufficient to be unaffected by solar wind implanted helium.

Radiation dose and its protection in the Moon from galactic cosmic rays and solar energetic particles: at the lunar surface and in a lava tube

The lunar surface is directly and continuously exposed to Galactic Cosmic ray (GCR) particles and Solar energetic particles (SEPs) due to the lack of atmosphere and lunar magnetic field. These charged particles interact with the lunar surface materials producing secondary radiations such as neutrons and gamma rays. In a departure from precise GCR and SEP data, we estimated the effective dose equivalent at the lunar surface and in a lunar lava tube in this paper by using PHITS, a Monte Carlo simulation tool. The effective dose equivalent due to GCR particles at the lunar surface reached 416.0 mSv yr−1 and that due to SEPs reached 2190 mSv/event. On the other hand, the vertical hole of the lava tube provides significant radiation protection. The exposure by GCR particles at the bottom of the vertical hole with a depth of 43 m was found to be below 30 mSv yr−1 while inside a horizontal lava tube, the value was less than 1 mSv yr−1 which is the reference value for human exposure on the Earth. We expect that the lunar holes will be useful components in the practical design of a lunar base to reduce radiation risk and to expand mission terms.

IMPLEMENTATION STRATEGY OF VISIBLE AND NEAR-INFRARED IMAGING SPECTROMETER ON YUTU-2 ROVER BASED ON VISION MEASUREMENT TECHNOLOGY

Abstract. The Chang'e-4 successfully landed on the far side of the moon in January 2019. By the 12th lunar day, its Yutu-2 rover had achieved a breakthrough travel distance of greater than 300 m. A visible and near-infrared imaging spectrometer (VNIS), consisting of a visible and near-infrared (VNIR) imaging spectrometer and a shortwave infrared (SWIR) spectrometer was used for detecting mineralogical compositions of lunar-surface materials. Because VNIS is fixed on the front of the rover, and the field-of-view (FOV) of VNIR and SWIR are small (8.5° and 3.6° respectively), approaching and accurately pointing at the specific science target depend completely on the precise control of the moving rover.In this paper, a successful method of VNIS target detection based on vision measurement is proposed. First, the accurate position of the target is calculated via navigation camera imaging. Then, the moving path is planned by considering the terrain environment, illumination, communication condition, and other constraints. After the rover moves to the designed position, the binocular imaging of the hazard-avoidance cameras are activated, the detection direction and forward distance are calculated according to the images, and the FOV trajectory of the VINS is predicted while moving. Finally, by choosing the required moving control parameters, the imaging field of the VINS accurately cover the detected targets visually.These methods have been verified many times, and the results show that they are effective and feasible. The research results based on the VNIS data have successfully revealed the material composition on the far side of the moon and have deepened human understanding of its formation and evolution.

Investigation of the depth and diameter relationship of subkilometer-diameter lunar craters

The depth and diameter relationship is one of the most important characteristics of craters; however, previous studies have focused mostly on large-diameter craters because of the limitations of image resolution. Recently, very high resolution images have been obtained that make it possible to expand this field of study to craters with diameters of < 1 km. Using images with resolution of up to 0.5 m, acquired by the Lunar Reconnaissance Orbiter, we investigated the depth and diameter relationship of fresh craters with subkilometer diameters. We selected craters from lunar maria and highlands, and we made precise measurements of their diameters and depths. The results show that the d/D ratio of small craters in the lunar maria and highlands, which varies from ∼0.2 to ∼0.1, is generally shallower than that of larger craters. We propose that the reason for the difference is because of the low strength of the lunar surface material. The fitted power law parameters of lunar mare and highland craters were found to be different, and that might be explained by terrain-related differences.

Calibrating a physical model based on Geant4 to calculate cosmogenic nuclide production rates on lunar surface

A physical model based on the open-source toolkit Geant4 for production rates of cosmogenic nuclei on the lunar surface is proposed and calibrated. The fluxes of proton and neutron beneath the lunar surface are obtained by simulating the physical processes between the cosmic-ray particles and the lunar surface material. By combining the experimental proton cross sections and the a posteriori neutron cross sections, we calculate the production rate depth profiles of long-lived nuclei (10Be, 14C, 26Al, 36Cl, and 53Mn). Through comparing experimental and theoretical data for these nuclei, we find that for all the selected nuclei, experimental and theoretical production rate depth profiles agree well with each other by introducing a single normalization factor. It means that the physical model based on Geant4 can also reproduce the depth profiles of cosmogenic nuclei, and that this model can be used by everyone worldwide. In addition, we predict the production rates of three stable nuclei (21Ne, 22Ne, and 38Ar).

Dependence of lunar mare microwave brightness temperature on FeO and TiO2

The Moon is known to radiate microwave emission as a grey body, depending on its surface emissivity and physical temperature. Measurement of lunar brightness temperature can reveal surface properties and thermal behavior, as it is dependent on the surficial material. To understand possible correlation and compare the results obtained from the measured data with those obtained from the theory, we have used the amount of lunar surface material (iron and titanium), measured by the lunar prospector mission, as a first quantity in the analysis. The lunar brightness temperature, measured by a microwave radiometer on Changé-1 mission, serves as the other variable in our analysis. Global maps of lunar surface materials have been generated from the lunar prospector data sets and presented in this article. A conditional coefficient, representing the correlation between microwave brightness temperature and lunar surface material has been defined, and its analysis has been carried out for the lunar Mare region. Results show that major contribution in brightness temperature comes from lunar regolith density driven component, while a small contribution is made by the lunar surface material. The correlation results disagree with the existing theoretical model used to describe the brightness temperature dependence with surface material. In this connection, a modified permittivity model is suggested for the Mare region, based on our correlation analysis.

Space weathering effects in Diviner Lunar Radiometer multispectral infrared measurements of the lunar Christiansen Feature: Characteristics and mitigation

Multispectral infrared measurements by the Diviner Lunar Radiometer Experiment on the Lunar Renaissance Orbiter enable the characterization of the position of the Christiansen Feature, a thermal infrared spectral feature that laboratory work has shown is proportional to the bulk silica content of lunar surface materials. Diviner measurements show that the position of this feature is also influenced by the changes in optical and physical properties of the lunar surface with exposure to space, the process known as space weathering. Large rayed craters and lunar swirls show corresponding Christiansen Feature anomalies. The space weathering effect is likely due to differences in thermal gradients in the optical surface imposed by the space weathering control of albedo. However, inspected at high resolution, locations with extreme compositions and Christiansen Feature wavelength positions – silica-rich and olivine-rich areas – do not have extreme albedos, and fall off the albedo- Christiansen Feature wavelength position trend occupied by most of the Moon. These areas demonstrate that the Christiansen Feature wavelength position contains compositional information and is not solely dictated by albedo. An optical maturity parameter derived from near-IR measurements is used to partly correct Diviner data for space weathering influences.

Thermal conductivity of surficial lunar regolith estimated from Lunar Reconnaissance Orbiter Diviner Radiometer data

The thermal conductivity of lunar regolith is a critical parameter in the determination of surface heat flow and understanding the nature of surface material. As a refinement on this thermophysical parameter, this study aims to present an estimation on the solid thermal conductivity of surficial lunar regolith based on the data of Lunar Reconnaissance Orbiter (LRO) Diviner radiometer. Theoretically, the thermal conductivity of lunar regolith is composed of solid thermal conductivity (i.e. the conductive contribution induced by the interactions among solid grains) and radiative thermal conductivity (i.e. the conductive contribution induced by the inter-granular radiation). The solid thermal conductivity depends on the thermal conductivity of solid grains as well as the effective contact areas among grains, which reflects the nature of lunar surface materials. It is well known that the surface temperature variation in the nighttime is dominated by the thermophysical parameter of surficial lunar regolith. A temperature model based upon heat conductive equation is adopted to correlate the thermophysical parameters of lunar regolith with the surface temperature. Diviner Level-3 bolometric temperature dataset is adopted as the proxy of lunar surface temperature. The estimation is carried out by searching for the optimal surficial solid component that makes the root-mean-square error (RMSE) between Diviner data and simulated temperatures minimum.The estimation result shows that the solid thermal conductivity of surficial lunar regolith has a wide variation range (0.0001–0.0300Wm−1K−1) between 60°N and 60°S. The solid thermal conductivity on the lunar surface has a prominent latitude dependence, which is doubted as the consequence of the specific surface energy variation versus latitude. In addition, the surface solid thermal conductivity in the older regions is ubiquitously higher than younger regions. This phenomenon would be relative with the variation of grain radius across the entire lunar surface.In addition, the enrichment of rock abundance at young impact craters makes the estimated solid thermal conductivity abnormally high. We also find a strong correlation between the absolute ages and the estimated surficial solid thermal conductivity of these craters. Based upon the fitted relation between them, the exact absolute ages of Crookes and Ohm are determined as 268 and 252Myr respectively.