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We demonstrate the creation of a large area of high-resolution (260 × 209 km2 at 1 m/pixel) DTM mosaic from the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images over the Chang'E-4 landing site at Von Kármán crater using an in-house deep learning-based 3D modelling system developed at University College London, called MADNet, trained with lunar orthorectified images and digital terrain models (DTMs). The resultant 1 m DTM mosaic is co-aligned with the Chang'E-2 (CE-2) and the Lunar Orbiter Laser Altimeter (LOLA)—SELenological and Engineering Explorer (SELENE) blended DTM product (SLDEM), providing high spatial and vertical congruence. In this paper, technical details are briefly discussed, along with visual and quantitative assessments of the resultant DTM mosaic product. The LROC NAC MADNet DTM mosaic was compared with three independent DTM datasets, and the mean differences and standard deviations are as follows: PDS photogrammetric DTM at 5 m grid-spacing had a mean difference of −0.019 ± 1.09 m, CE-2 DTM at 20 m had a mean difference of −0.048 ± 1.791 m, and SLDEM at 69 m had a mean difference of 0.577 ± 94.940 m. The resultant LROC NAC MADNet DTM mosaic, alongside a blended LROC NAC and CE-2 MADNet DTM mosaic and a separate LROC NAC, orthorectified image mosaic, are made publicly available via the ESA planetary science archive's guest storage facility. [ABSTRACT FROM AUTHOR]

The internal heat flow related to the Moon’s composition, interior structure, and evolution history is not well-constrained and understood on a global scale. Up to now, only two in situ heat flow experiments, Apollo 15 and 17 were deployed nearly 50 years ago. The measured high values of heat flow might be influenced by lateral heat at highland/mare boundaries and enhanced by heat production from radioactive elements enriched unit, and may also be disturbed by astronauts’ activities. In this study, we proposed a new method to retrieve heat flows at two permanently shadowed craters, Haworth and Shoemaker of the Moon’s south pole, from Chang’E-2 microwave radiometer data and Diviner observations. Our results show that the average heat flow is 4.9 ± 0.2 mW/m2. This provides a constraint for the bulk concentration of Thorium within the lunar south polar crust 656 ± 54 ppb, which helps us understand the Moon’s thermal evolution and differentiation.

Highlights • Find a new dome detection method with DEM and DOM. • Domes on the lunar surface have been detected with Chang'E-2 data. • Typical domes are selected and their topography, morphology and rheology are analyzed. • Formation mechanism of these domes is hypothesized. Abstract Lunar domes, which are distributed mainly in the lunar mare, were generated by lunar volcanism several billion years ago. In this context, identifying lunar mare domes and studying their morphological properties enhances the study of lunar volcanism. Traditionally, most lunar domes have been identified by manually analyzing images or topographic maps of the lunar surface; this approach has identified several lunar domes in specific local areas. To learn more about global lunar domes, it is necessary to identify them from the global lunar mare. In this paper, we present a method of identifying lunar domes using Chang'E-2 data. We demonstrate the identification of domes and analyze their morphological and geological properties. [ABSTRACT FROM AUTHOR]

Abstract The microwave radiation passively emitted from the Moon is valuable for investigating the physical properties of the lunar regolith. Microwave maps, which can reveal subsurface characteristics at depths of centimeters to meters, give clues to understanding the evolution of the lunar surface. China's Chang'E-2 (CE-2) spacecraft carried a microwave radiometer (MRM) and conducted passive microwave remote sensing of the Moon at 3, 7.8, 19.35 and 37 GHz (10, 3.84, 1.55 and 0.81 cm wavelengths) during 2010–2011. Brightness temperature (TB) data derived from the MRM orbital observations cover the entire Moon, and the time coverage is over a complete lunation. In this paper, we use spherical harmonic fits to model the TB variation as functions of local time and latitude. Using these fits, we normalized the day- and nighttime TB data measured at various local times into noon-time and midnight conditions. The spatial sampling of the normalized TB maps is ∼6 km/pixel, much higher than ground-based observations and higher resolution than the MRM maps derived from Chang'E-1. By removing the variation in TB related to local time and latitude, we produced a series of microwave maps that reveal differences in the properties of the regolith across the lunar surface. The microwave behavior of various lunar surface features can be explained primarily by differences in the microwave loss tangent of the materials. For example, we find that the high-Ti maria have high daytime TB and exhibit lower nighttime TB than the other maria as a result of the high dielectric loss tangent of ilmenite. The ilmenite-rich materials are less transparent to microwaves, and hence emissions emerge from closer to the surface, which is heated strongly in the day and cools quickly at night. Most fresh craters correspond to low-TB spots in the nighttime microwave maps, in contrast to their behavior as hot spots in nighttime infrared data, suggesting that the higher loss tangent of rocks (compared to soils) suppresses microwave emission at night. The Aristarchus plateau has a lower loss tangent relative to its surroundings because it is blanketed by fine-grained, rock-poor pyroclastic material. The pyroclastic blanket is more transparent to microwaves than the nearby maria, causing the plateau to have relatively cool daytime TB and warm nighttime TB as a consequence of microwave emissions that originate at greater depths The Orientale basin is another prominent anomaly in the microwave maps, indicating that Orientale materials differ in thermophysical and/or dielectric properties from typical highland lithologies. Brightness temperature differences among prominent rayed craters indicate that the very youngest crater rays (e.g., Giordano Bruno) have lower thermal inertia than older but still optically immature rays (e.g., Tycho). [ABSTRACT FROM AUTHOR]

Abstract Compared with other remote observations, brightness temperatures (T B) derived from microwave emission measurements provide a unique means to characterize the physical properties of the lunar surface. Using Chang'E-2 microwave radiometer data, we produced 12 global T B images of the lunar surface during a diurnal cycle with different local times separated by approximately 2 h. There are two types of remarkable T B units on the lunar surface, the "hot regions" occurring during the lunar day in the lunar Maria regions and the "microwave cold spots" occurring during the nighttime typically related to young craters. Compared with their surroundings, the hot regions are much warmer during the lunar day and slightly colder at night, while the microwave cold spots are much colder during the lunar night and slightly warmer in the daytime. Moreover, the T B heating and cooling rates of these two units are larger than others at the same average latitude where they are located during the lunar day, especially after sunrise and before sunset. The hot regions have a good agreement with the mare regions with high TiO 2 abundance. Besides, brightness temperatures in the lunar Maria correlate closely with their TiO 2 abundance. For most microwave cold spots, they agree with the young craters, and their brightness temperature distributions have a significant negative correlation with the lunar surface nighttime temperature and rock abundance. [ABSTRACT FROM AUTHOR]

The use of microwave radiation data collected by lunar orbiters to infer the lunar brightness-temperature (TB) distribution is of great importance to lunar scientific exploration. The TB data acquired by China's Chang'E-2 passive microwave radiometer (MRM) is one of the basic materials for lunar temperature mapping. Core issues of lunar microwave TB mapping include data fitting at different latitudes, outlier removal, and integrated spatial interpolation considering influencing factors. We applied a third-order Fourier function to fit the lunar TB data, which effectively removes outliers considering the fitting characteristic and three-sigma rule (FCTSR). Because the lunar surface temperature is influenced by a variety of factors such as topography and albedo, we then built a multi-factor co-kriging interpolation method to perform lunar TB mapping accurately. The cross-validation shows that, in terms of the mean-absolute-error and root-mean-square-error, the multi-factor co-kriging interpolation improves the mapping accuracy by 30%–60% compared to inverse distance interpolation and ordinary kriging interpolation. The analysis shows that topography and albedo are the most important factors influencing the lunar TB, and the TB maps at 37 GHz reveal cold spots that can be considered as younger craters. It is concluded that the proposed data fitting, denoising and spatial interpolation methods significantly improve the lunar TB mapping. The results and scientific data can also provide a basic energy map for lunar roving path planning and subsequent lunar exploration. • TB outliers were effectively removed using the fitting characteristics and three-sigma rule. • A multi-factor co-kriging method was developed to produce accurate lunar TB maps. • The co-kriging improves accuracy by 30%–60% compared to IDW and ordinary kriging. • The TB maps at 37 GHz reveal cold spots that can be identified as younger craters. [ABSTRACT FROM AUTHOR]

The precise orbit determination of Chang'E-2 is the most important issue for successful mission and scientific applications, while the lunar gravity field model with big uncertainties has large effect on Chang'E-2 orbit determination. Recently, several new gravity models have been produced using the latest lunar satellites tracking data, such as LP165P, SGM150J, GL0900D and GRGM900C. In this paper, the four gravity models mentioned above were evaluated through the power spectra analysis, admittance and coherence analysis. Effect of four lunar gravity models on Chang'E-2 orbit determination performance is investigated and assessed using Very Long Baseline Interferometry (VLBI) tracking data. The overlap orbit analysis, the posteriori data residual, and the orbit prediction are used to evaluate the orbit precision between successive arcs. The LP165P model has better orbit overlap performance than the SGM150J model for Chang'E-2100 km × 100 km orbit and the SGM150J model performs better for Chang'E-2100 km × 15 km orbit, while GL0900D and GRGM900C have the best orbit overlap results for the two types of Chang'E-2 orbit. For the orbit prediction, GRGM900C has the best orbit prediction performance in the four models.

The Chang’E-2 digital elevation model (DEM, named CE2TMap2015), which is the highest resolution DEM product in China, was released with global coverage of the lunar surface. A detailed geometric quality assessment of the product is desirable for wider applications by users. A novel procedure for evaluating DEM geometric quality, which investigates both the global geometric uncertainty and local gross errors, is proposed in this paper. First, the DEM was divided into regular blocks and matched with the reference DEM. Then, the characteristics of errors were investigated using the statistical information of the matched tie points. Next, the local outlier factor (LOF) algorithm was performed to locate the gross errors. In our experiment, CE2TMap2015 was evaluated using the proposed method, with SLDEM2015 as the reference DEM. The results show that there were widespread geometric inconsistencies with an area-weighted average of 183.1 m horizontally (with the standard deviation being 101.2 m) and 2.3 m vertically (with the standard deviation being 15.4 m). Gross errors were detected automatically and were excluded in the statistical analysis. The periodic errors were extracted in the frequency domain using a Fourier transform. Our research results provide instructional information for the utilization of CE2TMap2015 by world-wide users. The proposed method can be used in the assessment of other planetary DEMs.

The lunar map is a product of primary scientific objectives of lunar exploration. Aiming at the characteristics of the Chang'E-2 CCD data, an automatic stitching method used for 2C level CCD data from Chang'E-2 lunar mission is proposed. Combining with the image registration technique and the characteristics of Chang'E CCD images, the fast method proposed not only can overcome the contradiction of the high spatial resolution of the CCD images and the low positioning accuracy of the location coordinates, but also can speed up the processing and minimize the utilization of human resources to produce lunar mosaic map. Meanwhile, a new lunar map from 70ºN to 70ºS with spatial resolution of less than 10 m has been completed by the proposed method. Its average relative location accuracy of the adjacent orbits CCD image data is less than 3 pixels. [ABSTRACT FROM AUTHOR]

The orbit accuracy of the Chang’E-2 (CE-2) lunar probe is one of the most critical factors for a seamless mosaic of the global lunar topographic map. During the production of the CE-2 global lunar topographic map, a maximum deviation of kilometers magnitude existed in the horizontal direction of homologous points between neighboring images, while the maximum height deviation of these points is up to several hundred meters. This phenomenon indicates that current orbit determination results of CE-2 cannot truly reflect the relative position relationship between probe and lunar surface features. Against this background, global adjustment using images of the moon should be carried out to solve this problem. In this paper, the influence of CE-2 current orbit accuracy on the production of a global lunar topographic map will be analyzed based on the introduction of CE-2 observation data, including images and orbit data. Additionally, key technologies and technical processes of global adjustment using CE-2 images with high-resolution and large amounts of data will be researched. Finally, orbit optimization of CE-2 after global adjustment is analyzed, as well as the accuracy of the CE-2 global lunar topographic map for validation verification. [ABSTRACT FROM AUTHOR]

The lunar probe, Chang’E-2, is the first one to successfully achieve both the transfer to Sun–Earth libration point orbit and the flyby of near-Earth asteroid Toutatis. This paper, taking the Chang’E-2’s asteroid flyby mission as an example, provides a method to design low-energy transfers from the libration point orbit to an asteroid. The method includes the analysis of transfer families and the design of optimal impulse transfers. Firstly, the one-impulse transfers are constructed by correcting the initial guesses, which are obtained by perturbing in the direction of unstable eigenvector. Secondly, the optimality of one-impulse transfers is analyzed and the optimal impulse transfers are built by using the primer vector theory. After optimization, the transfer families, including the slow and the fast transfers, are refined to be continuous and lower-cost transfers. The method proposed in this paper can be also used for designing transfers from an arbitrary Sun–Earth libration point orbit to a near-Earth asteroid in the Sun–Earth–Moon system. [ABSTRACT FROM AUTHOR]

China’s space probe Chang’E-2 began its asteroid exploration mission on April 15, 2012 and had been in space for 243 days before its encounter with Toutatis. With no onboard navigation equipment available, the navigation of CE-2 during its fly-by of the asteroid relied totally on ground-based Unified S-Band (USB) and Very Long Baseline Interferometry (VLBI) tracking data. The orbit determination of Toutatis was achieved by using a combination of optical measurements and radar ranging. On November 30, 2012, CE-2 was targeted at a destination that was 15 km away from the asteroid as it performed its third trajectory correction maneuver. Later orbit determination analysis showed that a correction residual was still present, which necessitated another maneuver on December 12. During the two maneuvers, ground-based navigation faced a challenge in terms of the orbit determination accuracy. With the optimization of our strategy, an accuracy of better than 15 km was finally achieved for the post-maneuver orbit solution. On December 13, CE-2 successfully passed by Toutatis and conducted continuous photographing of Toutatis during the entire process. An analysis of the images that were taken from the solar panel monitoring camera and the satellite attitude information demonstrates that the closest distance obtained between CE-2 and Toutatis (Toutatis’s surface) was 1.9 km, which is considerably better than the 30 km fly-by distance that we originally hoped based on the accuracies that we can obtain on the satellite and Toutatis’ orbits. [ABSTRACT FROM AUTHOR]

Chang’E-2 (CE-2) has firstly successfully achieved the exploring mission from lunar orbit to Sun–Earth L2 region. In this paper, we discuss the design problem of transfer trajectory and at the same time analyze the visible segment of Tracking, Telemetry & Control (TT&C) system for this mission. Firstly, the four-body problem of Sun–Earth–Moon and Spacecraft can be decoupled in two different three-body problems (Sun–Earth + Moon Restricted Three-Body Problems (RTBPs) and Earth–Moon ephemeris model). Then, the transfer trajectory segments in different model are computed, respectively, and patched by Poincaré sections. The full-flight trajectory including transfer trajectory from lunar orbit to Sun–Earth L2 region and target Lissajous orbit is obtained by the differential correction method. Finally, the visibility of TT&C system at the key time is analyzed. Actual execution of CE-2 extended mission shows that the trajectory design of CE-2 mission is feasible. [ABSTRACT FROM AUTHOR]

The elemental abundances of lunar surface are the important clues to study the formation and evolution history of the Moon. In 2010, China's Chang'E-2 (CE-2) lunar orbiter carried a set of X-ray spectrometer (XRS) to investigate the elemental abundances of the lunar surface. During CE-2's life span around the Moon, the XRS experienced several events of solar flare. The X-ray solar monitor onboard recorded the spectra of solar X-rays at the same time. In this paper, we introduced the XRS instrument and data product. We analyzed the characteristics of the XRS data. Using the data obtained during an M solar flare event which had occurred on Feb. 16, 2011, we derived the elemental abundances of Mg, Al, Si, Ca and Fe of the lunar surface in the Oceanus Procellarum. Finally, we discussed the factors that influence the accuracy of the inversion. [ABSTRACT FROM AUTHOR]

After the Chang'e-2 spacecraft conducted a successful asteroid flyby, where is it flying to in interplanetary space? This question is answered via an introduction to the Chang'e-2's flight trajectory after asteroid flyby that is termed Earth co-orbital motion. Based on preliminary analysis using the dynamical systems theory, Poincaré sections concept, and routine optimization techniques, it is now predicted that, from the point of view of orbital mechanics, Chang'e-2 is capable of returning to the vicinity of the Earth in no more than 20 a and might be recaptured by the Earth if appropriate orbital maneuvers are going to be exerted, either by itself or by another spacecraft that captures Chang'e-2. [ABSTRACT FROM AUTHOR]

Shape modeling is fundamental to the analysis of dynamic environment and motion around asteroid. Chang'E-2 successfully made a flyby of Asteroid 4179 Toutatis and obtained plenty of high-resolution images during the mission. In this paper, the modeling method and preliminary model of Asteroid Toutatis are discussed. First, the optical images obtained by Chang'E-2 are analyzed. Terrain and silhouette features in images are described. Then, the modeling method based on previous radar model and preliminary information from optical images is proposed. A preliminary polyhedron model of Asteroid Toutatis is established. Finally, the spherical harmonic coefficients of Asteroid Toutatis based on the polyhedron model are obtained. Some parameters of model are analyzed and compared. Although the model proposed in this paper is only a preliminary model, this work offers a valuable reference for future high-resolution models. [ABSTRACT FROM AUTHOR]

The Chang'E-1 and Chang'E-2 missions have successfully obtained a huge amount of lunar scientific data, through the seven onboard instruments including a CCD stereo camera, a laser altimeter, an interference imaging spectrometer, an X-ray spectrometer, a microwave radiometer, a high-energy particle detector and a solar-wind ion detector. Most of the Chang'E data are now publicly available to the science community, and this article serves as an official guide on how these data are classified and organized, and how they can be retrieved from . This article also presents the detailed specifications of various instruments and gives examples of research progress made based on these instruments. [ABSTRACT FROM AUTHOR]

Abstract: This paper addresses lunar escape maneuvers of the first Chinese Sun–Earth L2 libration point mission by the CHANG'E-2 satellite, which is also the world's first satellite to reach the L2 point from a lunar orbit. The lunar escape maneuvers are heavily constrained by the remaining propellant and the condition of telemetry, track and command, among others. First, these constraints are analyzed and summarized to design a target L2 Lissajous orbit and an initial transfer trajectory. Second, the maneuver mathematical models are studied. The multilevel maneuver schemes which consist of phasing maneuvers and a final lunar escape maneuver are designed for actual operations. Based on the scheme analysis and comparison, the 2-maneuver scheme with a 5.3-h-period phasing orbit is ultimately selected. Finally, the mission status based on the scheme is presented and the control operation results are discussed in detail. The methodology in this paper is especially beneficial and applicable to a future multi-mission instance in the deep space exploration. [Copyright &y& Elsevier]

Highlights: [•] Three high degree lunar gravity field models are compared using various methods. [•] SGM150 is better for geophysical parameters inversion and orbit determination. [•] Localized spectrum can be used to judge the magnitude and depth of mascon. [Copyright &y& Elsevier]

Driven by curiosity about possible flight options for the Chang'e-2 spacecraft after it remains at the Sun-Earth L2 point, effective approaches were developed for designing preliminary fuel-optimal near-Earth asteroid flyby trajectories. The approaches include the use of modified unstable manifolds, grid search of the manifolds' parameters, and a two-impulse maneuver for orbital phase matching and z-axis bias change, and are demonstrated to be effective in asteroid target screening and trajectory optimization. Asteroid flybys are expected to be within a distance of 2 × 10 km from the Earth owing to the constrained Earth-spacecraft communication range. In this case, the spacecraft's orbital motion is significantly affected by the gravities of both the Sun and the Earth, and therefore, the concept of the 'heliocentric oscillating-Kepler orbit' is proposed, because the classical orbital elements of the flyby trajectories referenced in the heliocentric inertial frame oscillate significantly with respect to time. The analysis and results presented in this study show that, among the asteroids whose orbits are the most accurately predicted, 'Toutatis', '2005 NZ6', or '2010 CL19' might be encountered by Chang'e-2 in late 2012 or 2013 with total impulses less than 100m/s. [ABSTRACT FROM AUTHOR]

Chang'e-2, Chinese second lunar probe, was inserted into a 100 km altitude low lunar orbit on October 9th, 2010, its purpose is to continuously photograph the lunar surface and possibly chosen landing sites for future lunar missions. The probe will still carry considerable amount of propellant after completing all prescribed tasks in about six months. After the successful launch of Chang'e-2, we began designing the probe's subsequent flight scenario, considering a total impulse of 1 100 m/s for takeoff from low lunar orbit and a maximum 3×10 km distance for Earth-probe telecommunication. Our first-round effort proposed a preliminary flight scenario that involves consecutive arrivals at the halo orbits around the Earth-Moon L1/L2 and Sun-Earth L1/L2 points, near-Earth asteroid flyby, Earth return, and lunar impact. The designed solution of Chang'e-2's subsequent flight scenario is a multi-segment flight trajectory that serves as a reference for making the final decision on Chang'e-2's extended mission, which is a flight to the Sun-Earth L2 point, and a possible scheme of lunar impact via Earth flyby after remaining at the Sun-Earth L2 point was also presented. The proposed flight trajectory, which possesses acceptable solution accuracy for mission analysis, is a novel design that effectively exploits the invariant manifolds in the circular restricted three-body problem and the patched-manifold-conic method. [ABSTRACT FROM AUTHOR]

This paper addresses pre-LOI (before Lissajous orbit insertion) trajectory maneuvers for the libration point mission of CHANG′E-2, which is the first Chinese satellite to fly to the Sun-Earth L2 libration point and the first satellite ever to fly to the L2 point from lunar orbit. First, a transfer trajectory for the mission is designed based on InterPlanetary Superhighway theory under the constraint of the remaining propellant, TT&C (telemetry, track and command) and sunlight conditions. The effects of trajectory maneuver errors on the mission are also analyzed. Second, based on the analysis results, the article investigates the trajectory maneuver schemes for the lunar escape and transfer trajectory maneuvers employing mathematical models and operational strategies. The mission status based on our maneuver schemes is then presented, and the results of control operation and corresponding analysis are provided in detail. Finally, the future trajectory maneuver in the Lissajous orbit is discussed. According to the analysis of the CHANG′E-2 TT&C data, the trajectory maneuver schemes proposed in the article work properly and efficiently. [ABSTRACT FROM AUTHOR]

The Unified S-Band (USB) ranging/Doppler system and the Very Long Baseline Interferometry (VLBI) system as the ground tracking system jointly supported the lunar orbit capture of both Chang'E-2 (CE-2) and Chang'E-1 (CE-1) missions. The tracking system is also responsible for providing precise orbits for scientific data processing. New VLBI equipment and data processing strategies have been proposed based on CE-1 experiences and implemented for CE-2. In this work the role VLBI tracking data played was reassessed through precision orbit determination (POD) experiments for CE-2. Significant improvement in terms of both VLBI delay and delay rate data accuracy was achieved with the noise level of X-band band-width synthesis delay data reaching 0.2-0.3 ns. Short-arc orbit determination experiments showed that the combination of only 15 min's range and VLBI data was able to improve the accuracy of 3 h's orbit using range data only by a 1-1.5 order of magnitude, confirming a similar conclusion for CE-1. Moreover, because of the accuracy improvement, VLBI data was able to contribute to CE-2's long-arc POD especially in the along-track and orbital normal directions. Orbital accuracy was assessed through the orbital overlapping analysis (2 h arc overlapping for 18 h POD arc). Compared with about 100 m position error of CE-1's 200 km×200 km lunar orbit, for CE-2's 100 km×100 km lunar orbit, the position errors were better than 31 and 6 m in the radial direction, and for CE-2's 15 km×100 km orbit, the position errors were better than 45 and 12 m in the radial direction. In addition, in trying to analyze the Delta Differential One-Way Ranging (ΔDOR) experiments data we concluded that the accuracy of ΔDOR delay was dramatically improved with the noise level better than 0.1 ns and systematic errors better calibrated, and the Short-arc POD tests with ΔDOR data showed excellent results. Although unable to support the development of an independent lunar gravity model, the tracking data of CE-2 provided evaluations of different lunar gravity models through POD. It is found that for the 100 km×100 km lunar orbit, with a degree and order expansion up to 165, JPL's gravity model LP165P did not show noticeable improvement over Japan's SGM series models (100×100), but for the 15 km×100 km lunar orbit, a higher degree-order model can significantly improve the orbit accuracy. [ABSTRACT FROM AUTHOR]

Abstract: Chang'E-2 gamma-ray spectrometer (GRS) is included in the payload of Chinese second lunar mission Chang'E-2 that has been launched in October 2010. Specific objectives of the GRS are to map abundance of O, Si, Fe, Ti, U, Th, K, and, perhaps, Mg, Al, and Ca, to depth of about 20cm. The energy resolution and detection efficiency were improved compared with Chang'E-1 GRS. We will describe the design of GRS, which used LaBr3 for its main detector, and present its performance in this paper. Moreover, the initial result of Chang'E-2 GRS is reported. [Copyright &y& Elsevier]