Meng-Hua Zhu

• PhD
• Professor (Full) at Macau University of Science and Technology

Plain Language Summary The analyses of the composition of lunar soil are crucial for unraveling the Moon's complicated history. China's Chang'e‐5 (CE‐5) mission collected 1.731 kg lunar soil from a depth of 1 m within a relatively young region. The detailed examinations of the CE‐5 soils showed that less than 5% of the components originated from di...

The widely accepted accretion scenario of planet formation suggests that the Moon experienced a violent bombardment in its early history. The accretion scenario predicts that a total of ~300 basins with sizes greater than 300 km formed throughout its bombardment history; however, only ~40 basins of this size are identified on the Moon. The cause fo...

Plain Language Summary In June 2024, China's Chang'e‐6 probe successfully returned the first‐ever lunar farside samples of 1,935.3 g, from the Apollo basin within the South Pole Aitken (SPA) basin, the largest, deepest, and oldest impact basin on the Moon. The age and sources of the samples are vital in understanding the geological history of the l...

In many clinical and research settings, the scarcity of high-quality medical imaging datasets has hampered the potential of artificial intelligence (AI) clinical applications. This issue is particularly pronounced in less common conditions, underrepresented populations and emerging imaging modalities, where the availability of diverse and comprehen...

Asteroids pose potential hazards to Earth. The recent NASA Double Asteroid Redirection Test mission successfully demonstrated the change of an asteroid’s orbit by a kinetic impactor. This study focuses on impact-induced vertical momentum transfer efficiency ( β − 1) considering various impact angles and subsurface boulder arrangements. Utilizing th...

This study investigates silicate liquid immiscibility (SLI) microstructures in the Chang’E-5 (CE-5) lunar ferrobasalt sample, the youngest recovered mare basalt (ca. ~2.0 Ga). Employing advanced high-resolution imaging techniques and chemical analysis, we examined a subophitic fragment, revealing two distinct types of microstructures indicative of...

Polyimide (PI) stands as a foundational material in the aerospace industry and high-energy-density science, and its shock response under extreme conditions constitutes an increasing focus within the academic community. However, given the sophisticated molecular structure and stacking state of chains, the understanding of how PI mobilizes multiple m...

Mesosiderites are thought to be created by a catastrophic impact that mixes the silicate crust with the metallic core of a differentiated asteroid(s). The metal‐silicate mixing event greatly affects the subsequent geological evolution of the mesosiderite parent body. To gain a better understanding of this mixing event, we carried out studies on oli...

Physical properties (e.g., ejecta size and distribution) of impact craters are crucial and essential to understand ejecta excavation and deposition process, estimate rock breakdown rate, and reveal their the evolution characteristics. However, whether these physical properties are scale-dependent and how they evolve in different radial regions need...

Reflectance spectroscopy is a powerful tool to remotely identify the mineral and chemical compositions of the lunar regolith. The lunar soils contain silicate minerals with prominent absorption features and glasses with much less distinctive spectral features. The accuracy of mineral abundance retrieval may be affected by the presence of glasses. I...

The commonly adopted ejecta deposit models always assume vertical impacts for simplification. However, most impacts on planetary surfaces are oblique, which produce significantly different ejecta patterns from vertical impacts. Although the asymmetric ejecta patterns from oblique impacts have been studied in laboratory experiments, they cannot be d...

The perfectly matched layer (PML) is one of the most popular absorbing boundary conditions for simulating seismic waves. In theory, the PML can absorb incident waves at any incident angle and any frequency in a medium. However, numerical reflections will be generated after the PML has been discretized. Therefore, how to reduce the reflections of di...

Numerous linear grooves have long been recognized as covering the surface of Phobos, but the mechanisms of their formation are still unclear. One possible mechanism is related to the largest crater on Phobos, the Stickney crater, whose impact ejecta may slide, roll, bounce, and engrave groove-like features on Phobos. When the launch velocity is hig...

The maximum time step size for the explicit finite-difference scheme complies with the Courant–Friedrichs–Lewy (CFL) stability condition, which essentially restricts the optimization and tuning of the communication-intensive massive seismic wave simulation in a parallel manner. This study brings forward the model-order reduction (MOR) method to sim...

Introduction: Nearly all asteroids impact a planet at oblique incident angles. Impact probability on a planet indicates that the most probable angle of impact is 45° from the surface plane, and ~ 50% of all impacts occur between 30° to 60° [1, 2]. Laboratory experiments of oblique impacts show that the ejecta pattern varies significantly with incid...

The Moon reveals striking asymmetries in the crustal structure and chemical composition between its nearside and farside. With the gravity‐based crustal thickness model, we find that most large impact basins with rim diameters greater than 450 km on the nearside have no crustal annulus, which is instead common for basins on the farside. Previous im...

The Moon has experienced an intense bombardment history since its formation1. Fragments of the impactor can remain on the lunar surface2–4 and can provide evidence of the evolution of the impactor composition and impact population in the Earth–Moon system3–5. However, the retained impactor fragments previously identified in the Apollo samples have...

The spatial distribution of mare basalts, titanium and KREEP (potassium, rare earth elements and phosphorus) on the Moon is asymmetrical between the nearside and farside. These asymmetries cannot be readily explained by solidification of a global magma ocean and subsequent mantle overturn, which should result in a layered and spherically symmetric...

Abundances of the highly siderophile elements (HSEs) in silicate portions of Earth and the Moon provide constraints on the impact flux to both bodies, but only since ~100 Myr after the beginning of the Solar System (hereafter tCAI). The earlier impact flux to the inner Solar System remains poorly constrained. The former dwarf planet Vesta offers th...

Plain Language Summary Lunar samples provide the ground‐truth reference to reveal the Moon's evolutional history. China's Chang’e‐5 mission is the first lunar exploration program that returned samples since the Luna 24 mission in 1976. Although the sampling site is a young mare basalt, the long‐term impact gardening and multiple volcanic episodes m...

Von Kármán crater's floor was flooded with mare basalts during the Imbrian period. This site is the target of China's ongoing Chang'e-4 mission that includes the Yutu-2 rover and its instrumental payload. The Zhinyu crater, one of the largest craters within a few tens of kilometers from the landing site, is the product of a fresh impact that excava...

The South Pole–Aitken (SPA) basin is the oldest and largest impact structure on the Moon, and it gives particular insight on the lunar interior composition1–3. However, the surface of the SPA basin has been substantially modified by consequent impacts and basalt flooding. The exploration of the surficial material and the substructure of the SPA bas...

Context. The Yutu-2 rover of the Chang’E-4 (CE-4) mission measured the lunar phase curves in the Von Kármán crater, South Pole-Aitken basin. Aims. We aim to study the photometric properties of the regolith at CE-4’s landing site and compare them with those of Chang’E-3 (CE-3) in order to understand the regolith physical properties of the two landin...

The importance of highly siderophile elements (HSEs) to track planetary late accretion has long been recognized. However, the precise nature of the Moon's accretional history remains enigmatic. There exists a significant mismatch of HSE budgets between the Earth and Moon, with the Earth disproportionally accreted far more HSEs than the Moon did. Se...

The Moon exhibits striking geological asymmetries in elevation, crustal thickness, and composition between its nearside and farside. Although several scenarios have been proposed to explain these asymmetries, their origin remains debated. Recent remote sensing observations suggest that (1) the crust on the farside highlands consists of two layers:...

The Chang'E-4 spacecraft successfully landed in Von Kármán crater inside the South Pole-Aitken basin on the lunar far side on January 3, 2019 and the Yutu-2 Rover has performed explorations on the lunar surface for nine lunar days as of September 2019. Our earlier analysis of the visible and near-infrared spectrometer measurements made by the Yutu-...

Chang'e‐4 (CE‐4) achieved the first farside landing in Von Kármán crater. In the landing site, linear features have been identified previously from SLDEM and considered to be ejecta from the neighboring Finsen crater. The 5 cm grid spacing digital elevation model of the landing site, generated from the rover's panoramic images, provides more detail...

Chang’E-4 landed in the South Pole-Aitken (SPA) Basin, providing a unique chance to probe the composition of the lunar interior. Its landing site is located on ejecta strips in Von Kármán crater that possibly originate from the neighboring Finsen crater. A surface rock and the lunar regolith at 10 sites along the rover Yutu-2 track were measured by...

Partially buried craters on the Moon are those craters whose distal ejecta are covered by lava flows and where the crater rim crest still protrudes above the mare plain. Based on the difference in rim heights between a partially buried crater and an unburied crater, previous studies estimated the thicknesses of the lunar mare basalts. However, thes...

During its first two lunar day measurements, the visible and near‐infrared spectrometer on board the Yutu‐2 Rover of the Chang'E‐4 mission acquired six in situ reflectance spectra from the floor of Von Kármán crater within the South Pole‐Aitken basin. A spectral lookup table search has shown that the regolith at the landing site contains 56–72% pla...

Plain Language Summary Beginning with the Apollo era, spacecraft observations have shown that the Moon has striking asymmetries between its nearside and farside in topography, crustal thickness, and composition. These asymmetries are likely a product of very early geological processes on the Moon. Understanding their formation mechanism may help to...

The importance of highly siderophile elements (HSEs; namely, gold, iridium, osmium, palladium, platinum, rhenium, rhodium and ruthenium) in tracking the late accretion stages of planetary formation has long been recognized. However, the precise nature of the Moon’s accretional history remains enigmatic. There is a substantial mismatch in the HSE bu...

The formation of the South Pole‐Aitken (SPA) basin is thought to excavate the deep crust or mantle because of its large size. The pervasive orthopyroxene‐dominated materials found across the basin suggest that they either represent the SPA impact melt or the excavated materials from the lower crust and/or upper mantle. This study analyzes the relat...

We present the thorium distribution on the lunar surface derived from observations by the Chang’E-2 gamma-ray spectrometer ( CE-2 GRS). This new map shows a similar thorium distribution to previous observations. In combination with this new thorium map and impact cratering model, we investigate the origination of thorium on the Moon’s highlands, wh...

Selenophysical parameters can be estimated based on admittance between gravity and topography, especially high-precision GRAIL gravity and LOLA topography data. These parameters include load ratio between subsurface and surface loads, crustal thickness, crustal density, and effective elastic thickness. Considering non-negligible membrane stress, th...

A giant impact on the Procellarum region on the lunar nearside has been proposed as a possible mechanism to explain different aspects of the lunar dichotomy, including crust thickness, topography and composition. In this work we study the first steps of the post-impact evolution of the lunar mantle and crust by modeling impact melting, melt pool fo...

Impact craters are formed by the displacement and ejection of target material. Ejection angles and speeds during the excavation process depend on specific target properties. In order to quantify the influence of the constitutive properties of the target and impact velocity on ejection trajectories, we present the results of a systematic numerical p...

We investigate how different temperature gradients of the Moon affect the ejection of lithic and molten materials for impact basin several hundred kilometers in diameter to quantify the thickness and melt content of ejecta blanket as a function of radial distance. We find, by means of numerical modeling, that the ejecta thickness and melt content,...

Relatively denser basalt infilling and the upward displacement of the crust-mantle interface are thought to be contributing factors for the quasi-circular mass anomalies for buried impact craters in the lunar maria. Imagery and gravity observations from the Lunar Reconnaissance Orbiter (LRO) and dual Gravity Recovery and Interior Laboratory (GRAIL)...

Whether or not background secondary craters dominate populations of small impact craters on terrestrial bodies is a half-century controversy. It has been suggested that small craters on some planetary bodies are dominated by background secondary craters based partly on the steepened slope of crater size-frequency distribution (CSFD) towards small d...

In contrast to lunar regolith, which is dominated by impact melt particles (agglutinates), samples from the asteroid Itokawa (25143), collected by the Hayabusa mission, exhibit a strong deficit in agglutinates. To investigate the amount of shock-induced melting and its distribution in the ejecta we simulate hypervelocity impacts into targets with v...

We report on a newly discovered morphological feature on the lunar surface, here named Ring-Moat Dome Structure (RMDS). These low domes (a few meters to ~20 m height with slopes <5°) are typically surrounded by narrow annular depressions or moats. We mapped about 2,600 RMDSs in the lunar maria with diameters ranging from tens to hundreds of meters....

The lunar surface features diverse impact structures originating from its early bombardment; the largest among them are the lunar basins. Basin-forming impacts delivered large amounts of energy to the target and expelled lots of material that deposited as an insulating blanket in the vicinity of the impact. Here, we investigate how such processes m...

Introduction: Hypervelocity impacts create high-pressure shock waves that lead to distinct shock-metamorphic effects in both projectile and target. Specifically, the point of impact is surrounded by hemispherical zones of decreasing shock pressure and, hence, by a continuum of decreasingly intense shock-metamorphic effects in the target material [1...

We investigated the ejection mechanics by a complementary approach of cratering experiments, including the microscopic analysis of material sampled from these experiments, and 2-D numerical modeling of vertical impacts. The study is based on cratering experiments in quartz sand targets performed at the NASA Ames Vertical Gun Range. In these experim...

We simulate the impact induced target fragmentation and describe the movement of ejected particles and their interaction with an atmosphere using iSALE.

Preliminary SEM and EMPA results are reported for new Apollo 17 basaltic regolith fragments

We proposed a new method to estimate the primary ejecta and local materiel of the Orientale basin on the Moon

The formation and structure of the Orientale basin on the Moon has been extensively studied in the past; however, estimates of its transient crater size, excavated volume and depth, and ejecta distribution remain uncertain. Here we present a new numerical model to reinvestigate the formation and structure of Orientale basin and better constrain imp...

The Chang'E-3 lunar penetrating radar (LPR) observations at 500 MHz reveal four major stratigraphic zones from the surface to a depth of ∼20 m along the survey line: a layered reworked zone (<1 m), an ejecta layer (∼2-6 m), a paleoregolith layer (∼4-11 m), and the underlying mare basalts. The reworked zone has two to five distinct layers and consis...

The panorama cameras onboard the Yutu Rover of the Chang'E-3 lunar mission acquired hundreds of high-resolution color images of the lunar surface and captured the first in-situ lunar opposition effect (OE) since the Apollo era. We extracted the phase curve and the color ratio in three bands with the phase angle range from 2° to 141°. Photometric in...

X-ray fluorescence remote sensing technique plays a significant role in the chemical compositions research of the Moon. Here we describe the data analysis method for China's Chang'E-2 X-ray spectrometer (CE2XRS) in detail and present the preliminary results: the first global Mg/Si and Al/Si maps on the lunar surface. Our results show that the distr...

The visible and near-infrared imaging spectrometer on board the Yutu Rover of Chinese Chang'E-3 mission measured the lunar surface reflectance at a close distance (~1 m) and collected four spectra at four different sites. These in situ lunar spectra have revealed less mature features than that measured remotely by spaceborne sensors such as the Moo...

The composition of mare basalt units in the Orientale Basin are investigated by using the potassium (K) map derived from Chang'E-2 gamma-ray spectrometer (CE-2 GRS) and FeO map derived from Clementine UV–Vis data set. Together with crater retention ages of the mare basalts from literature data, we aim to investigate possible magma sources underneat...

Introduction: The Australasian tektite strewnfield provides evidence for a major impact cratering event in southeast Asia ~800000 years ago [1]. Although the strewnfield is the youngest and largest and covers almost 25-30% of the Earth´s surface, the source crater is not yet identified. The impact crater is believed to range in size between 40-100...

The new global Th map derived from CE-2 GRS indicates a possible indigenous Th on the lunar highlands besides the Imbrium impact contribution.

Regolith thickness over the Sinus Iridum region is estimated using morphology and size-frequency distribution of small impact craters from LROC NAC images.

[1] Close observations by the Chang'E-2 spacecraft reveal that the surface of asteroid (4179) Toutatis is characterized by abundant impact craters with most of them being degraded by surface resetting. The less degraded large crater with a diameter of ~800 m at the south pole is estimated to be produced by an impactor with a diameter of ~50 m from...

KREEP materials were thought to be last crystallized at the lunar crust and mantle boundary. Impact cratering and volcanism are mainly responsible for their distributions on the lunar surface. Therefore, observation of global KREEP materials and investigation of distributions in the areas of large basins are of critical importance to understand the...

We propose a numerical modeling to calculate the contribution of secondary mass wasting to the total volume and thickness of ejecta blankets at impact craters.

Gamma ray spectrometers, as one of the major payloads onboard China's Chang'E-1/2 spacecrafts, were aimed to provide maps of the abundances of major elements, O, Si, Mg, Al, Ca, Ti, Na, and Fe, and of the natural radioactive elements, U, Th, and K, in the subsurface of the Moon. These elements presented on the lunar surface are the end products of...

The global map of potassium is represented in this paper from Chang’E-1 (CE-1) Gamma-ray Spectrometer (CGRS) for its one-year mission. Assuming a linear relationship between net count rate and its abundance, the average potassium abundance of individual landing sites is used as ground-truth for the calibration to derive the global map of absolute c...

We studied the Th content of Hellas with topographic and hydrological features, and hope to resolve related questions: the shift of the topographic and Th distribution boundaries, the geological processes experienced, or the effect of water leaching.

The Chang’E-1(CE-1) spacecraft took a gamma-ray spectrometer (hereafter, CGRS) to detect the element distributions on the lunar surface in a circular, 200 km altitude, polar orbit with approximately 2 h periodicity. CGRS consists of two large CsI(Tl) crystals as the main and anticoincidence detectors. The large CsI crystal of CGRS has a higher dete...

This abstract describes the preliminary radioactive results on the lunar surface from Chang'E-1 gamma-ray spectrometer.

In the present paper, a new criterion is derived to obtain the optimum fitting curve while using Cubic B-spline basis functions to remove the statistical noise in the spectroscopic data. In this criterion, firstly, smoothed fitting curves using Cubic B-spline basis functions are selected with the increasing knot number. Then, the best fitting curve...

In this paper, we present an iterative filtering method to estimate the background of noisy spectroscopic data. The proposed method avoids the calculation of the average full width at half maximum (FWHM) of the whole spectrum and the peak regions, and it can estimate the background efficiently, especially for spectroscopic data with the Compton con...

In this paper, a heuristic approach based on Slavic's peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be us...

In this paper, the least square fitting method with the cubic B-spline basis functions is derived to reduce the influence of statistical fluctuations in the gamma ray spectra. The derived procedure is simple and automatic. The results show that this method is better than the convolution method with a sufficient reduction of statistical fluctuation....

We consider the thorium distributions that are coincident with the distribution of ejecta after the Mare Imbrium impact occurs on the lunar surface and derive a simple model on the spherical target to predict the thickness of Imbrium ejecta deposits as a function of distance from the centre of the Imbrium basin. Then we use the result of Lunar Pros...

We present an approach to estimate the width of peak regions for the background elimination of gamma ray spectrum. The synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectra, we find that the approach is simple and effective enough for the background elimination c...

In this paper, we present the development of a many-knot spline method derived to remove the statistical noise in the spectroscopic data. This method is an expansion of the B-spline method. Compared to the B-spline method, the many-knot spline method is significantly faster. Comment: 3pages, 2 figures

In this paper, a simple and automatic method for smoothing gamma-ray spectra is derived. This method is based on B-spline basis functions with least squares fitting used to reduce the influence of statistical fluctuations. The results show that this method is better than traditional method with a more complete reduction of statistical fluctuation.