Lunar Sample Return Research Articles

Space exploration in China

Abstract In the past 20 years, China has implemented Manned Space Engineering, Lunar and Mars exploration missions, becoming an active participant in human space travel and exploration. So far China has established its Space Station in 2022, continuing to carry out large-scale space science research for the next 10-15 years. China has successfully achieved the soft landing on the lunar, far side of the Moon and on the Mars surface, obtained 1.73 kg of lunar sample, and will also implement the lunar Antarctic sample return and Mars sample return mission later. The exploration missions for the asteroid and Jupiter system are being prepared. Overall the future science exportations and collaborations between human and robot, as well as the utilisation of extraterrestrial resources will become the new development focus. Chinese scientists eagerly look forward to close international collaboration.

Small lunar crater identification and age estimation in Chang'e-5 landing area based on improved Faster R-CNN

The Chang'e-5 (CE-5) mission marks China's first lunar sample return endeavor, with its landing site (43.06°N, 51.92°W) situated in the Mons Rümker region of the northern Oceanus Procellarum on the Moon. This region hosts some of the youngest mare basalts of the Moon and contains a relatively youthful geologic unit characterized by crater's equilibrium diameters slightly over 100 m. By refining the Faster Region-based Convolutional Neural Network (Faster R-CNN) algorithm and leveraging high-resolution imagery to create training samples, accurate identification of lunar craters can be achieved. In this study, we enhance the algorithm in aspects such as anchor boxes and Region of Interest alignment. Additionally, we have utilized high-resolution images for training, and identify and statistics craters within the CE-5 landing area. Ultimately, our model attains a validation set Recall of 90%, Precision of 69%, and an Average Precision score of 0.83. Notably, in certain scales, such as for the crater larger than 400 m, recognition results reach Precision of 88% and Recall of 89%. The findings of this study are mapped into a crater catalog. Furthermore, we predict crater density and integrate it with geochronological functions to estimate the absolute model age of nine major geologic units within the CE-5 landing area. The results are generally in agreement with those of other studies who have used manual methods for crater counting, and verify the correctness of our automatic crater identification results.

Design of In-Orbit Sample Container Transfer Mechanism for Chang’E-5 Lunar Sample Return Mission

In this paper, a pawl composite linkage transfer mechanism is designed for the automatic in-orbit sample transfer mission of Chang’E-5 lunar sample return mission, which can realize the sample container in-orbit transfer under various critical constraints such as lightweight, miniaturization, and narrow working space. Resistance during the whole process as well as the sensitive factors that affect the resistance during the sample container transfer process are investigated and designed. The sample container transfer process has been verified by the test system on the ground, indicating that the design can satisfy the requirements of the sample transfer mission. The developed transfer mechanism completed the Chang’E-5 sample return mission successfully with good consistency between space and ground, verifying the correctness and effectiveness of the design.

Stiffness Design of Active Capture Claw-Type Docking Mechanism for Lunar Sample Return

The docking mechanism is the key system for realizing the lunar-orbit docking mission of two spacecraft, which needs to have both capture correction and connection hold functions. The different stiffness requirements between the capture correction process, where low stiffness is desired, and the connection hold process, where high stiffness is desired, pose a significant challenge to the design of the docking mechanism. In this paper, an active capture claw docking mechanism is designed. Under the constraints of being lightweight and having an envelope size, three sets of independent claw mechanisms are designed using the modular design idea to achieve the performance optimization and function integration of the docking mechanisms. The theoretical model of the collision dynamics between the active and passive docking mechanisms is established; the stiffness value range of the docking mechanism is determined, and the typical docking conditions are simulated and verified. The results show that the stiffness design in this paper can satisfy the requirements of the two docking processes. The active capture claw docking mechanism developed was applied to the lunar surface sample return mission successfully and played an important role in the lunar-orbit docking mission.

Landing site of the Chang’e-6 lunar farside sample return mission from the Apollo basin

To address questions about the multiple lunar nearside–farside dichotomies and to provide new insights into both the early impact history of the Solar System and the geological evolution of the Moon, the Chang’e-6 (CE-6) landing zone has been selected to lie within the lunar farside South Pole–Aitken (SPA) basin in the southern part of the Apollo basin (150–158° W, 41–45° S), a site that provides access to a diversity of SPA material. Here, we describe the geomorphology, geology and chronology of three candidate sampling sites within this zone that are likely to ensure safe landing and sampling. The geological characteristics indicate that CE-6 is expected to collect lunar farside SPA ejecta fragments, possible mantle material and young (roughly 2.40 Gyr-year-old) and/or old (roughly 3.43 Gyr-year-old) basaltic material, all of which will provide important guidance for future in situ farside sample collection and deepen our understanding of the evolution of the Moon.

A catalogue of meter-scale impact craters in the Chang'e-5 landing area measured from centimeter-resolution descent imagery

Chang'e-5 (CE-5) mission, the first lunar sample return mission of China, landed in Northern Oceanus Procellarum (51.92°W, 43.06°N) on Dec. 1, 2020. The descent camera onboard the CE-5 lander collected hundreds of descent images during the landing process. These high-resolution images are used to generate high resolution digital orthophoto map (DOM) and digital elevation model (DEM), providing a data basis for the detailed analysis of the geology and topography of the landing area. Impact craters are the most common landforms on the Moon, and small craters measured from high resolution data are very important for understanding the impacting process and the properties of the lunar surface. In this research, we create a catalogue of small craters measured from the centimeter-resolution image mapping products in the CE-5 landing area, and most of the craters are smaller than 100 m in diameter. The distribution and morphological characteristics of the craters are analyzed, including the completeness diameter, the spatial density distribution and the relationship between depth and diameter. The mean depth-to-diameter ratio of 231 craters with diameters ranging from 7.0 to 371.2 m and depths ranging from 0.21 to 45.9 m in CE-5 landing area is ~0.055. This result indicate that our catalogue has slightly low d/D ratios compared with other larger craters and the small craters in Chang'e-4 landing area.

Scientific objectives and payloads of the lunar sample return mission—Chang’E-5

In the early morning on December 17, 2020 Beijing time, China's chang'E-5 probe successfully returned to the Earth with 1731 g of lunar samples after completing drilling, shoveling, packaging of lunar soil and scientific exploration on lunar surface. It is the successful completion of the third phase of China's lunar exploration project, namely “circling, landing and returning to the moon”. The scientific objectives of CE-5 mission are to carry out in situ investigation and analysis of the lunar landing region, laboratory research and analysis of lunar return samples. This paper analyzes scientific exploration tasks of CE-5 mission conducted on the lunar surface, and carries out the scientific payload system architecture design and individual scientific payload design with the scientific exploration task requirements as the target, and proposes the working mode and main technical index requirements of the scientific payloads. Based on the preliminary geological background study of the Mons Ruemker region which is the landing region of CE-5, the lunar scientific exploration and the laboratory physicochemical characterization of the return samples are of great scientific significance for our in-depth understanding of the formation and evolution of the Earth-Moon system and the chemical evolution history of the lunar surface.

Mineral chemistry and 3D tomography of a Chang’E 5 high-Ti basalt: implication for the lunar thermal evolution history

In December 2020, Chang’E-5 (CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain, a great distance from those of Apollo and Luna missions. These young mare basalts bear critical scientific significance as they could shed light on the nature of the lunar interior (composition and structure) as well as the recent volcanism on the Moon. In this article, we investigated a CE-5 basalt sample (CE5C0000YJYX065) using a combination of state-of-art techniques, including high resolution X-ray tomographic microscopy (HR-XTM), energy dispersive X-ray spectroscopy (EDS)-based scanning electron microscope (SEM), and electron probe microanalysis (EPMA) to reveal its 3D petrology and minerology. Our results show that this sample has a fine- to medium-grained subophitic texture, with sparse olivine phenocrysts setting in the groundmass of pyroxene, plagioclase, ilmenite and trace amounts of other phases. It has an extremely high ilmenite modal abundance (17.8 vol%) and contains a significant amount (0.5 vol%) of Ca-phosphate grains. The mineral chemistry is in excellent agreement with that of Apollo and Luna high-Ti basalts. The major phase pyroxenes also display strong chemical zoning with compositions following the trends observed in Apollo high-Ti basalts. Based on current data, we came to the conclusion that CE5C0000YJYX065 is a high-Ti mare basalt with a rare earth element (REE) enriched signature. This provides a rigid ground-truth for the geological context at the CE-5 landing site and clarifies the ambiguity inferred from remote sensing surveys.

Trajectory Determination of Chang’E-5 during Landing and Ascending

Chang’E-5 (CE-5) is China’s first lunar sample return mission. This paper focuses on the trajectory determination of the CE-5 lander and ascender during the landing and ascending phases, and the positioning of the CE-5 lander on the Moon. Based on the kinematic statistical orbit determination method using B-spline and polynomial functions, the descent and ascent trajectories of the lander and ascender are determined by using ground-based radiometric ranging, Doppler and interferometry data. The results show that a B-spline function is suitable for a trajectory with complex maneuvers. For a smooth trajectory, B-spline and polynomial functions can reach almost the same solutions. The positioning of the CE-5 lander on the Moon is also investigated here. Using the kinematic statistical positioning method, the landing site of the lander is 43.0590°N, 51.9208°W with an elevation of −2480.26 m, which is less than 200 m different from the LRO (Lunar Reconnaissance Orbiter) image data.

Experimental research on a precise terrain reconstruction algorithm based on stereo images for the Chang’E-5 lunar sample return mission

<p indent=0mm>An exact terrain reconstruction algorithm based on stereo images is proposed for the Chang’E-5 lunar sample return mission. First, the paper presents a brief introduction to the proposed algorithm. Then, an analysis of the factors influencing terrain reconstruction and the geometric transformation model between the reconstructed and measured points are described. Finally, some conclusions drawn based on the experiment results of China’s Chang’E-5 probe system are presented. The approved algorithm can achieve high accuracy (the mean distance between the reconstructed and measured points was less than <sc>6.0 mm,</sc> and the variance was less than <sc>13.0 mm)</sc> and stability for terrain reconstruction.

Detailed Morphologic Mapping and Traverse Planning for a Rover-based Lunar Sample Return Mission to Schrödinger Basin

Abstract Schrödinger basin, a 312 km diameter complex impact structure located near the lunar south pole, has been widely cited as a prime target for future lunar exploration. In 2020 NASA identified Schrödinger as a high-priority landing site for a 2024 mission supported by the Payloads and Research Investigations on the Surface of the Moon solicitation and the Commercial Lunar Payload Services program. Schrödinger basin hosts an uplifted peak ring that would provide a surface mission with access to materials that originated deep within the lunar crust, as well as material ejected from the larger South Pole–Aitken basin. Schrödinger basin also hosts well-preserved mare and pyroclastic deposits that could provide valuable insight into volcanic processes on the Moon. This study used high-resolution Wide Angle Camera and Narrow Angle Camera images from the Lunar Reconnaissance Orbiter, elevation data from the Lunar Orbiter Laser Altimeter, and spectral data from the Clementine mission to produce a high-resolution morphologic map of the basin center consisting of 10 distinct morphologic units. This new map was used to plan traverse paths for a rover mission to the region. The design requirements for this traverse were based on those originally developed for the multiagency Human-Enhanced Robotic Architecture and Capability for Lunar Exploration and Science (HERACLES) mission and the Canadian Space Agency Precursor to Humans And Science Rover concept. The proposed traverse path includes up to 20 sample collection stops with the goal of better understanding lunar chronology, lunar volcanism, and the impact cratering process.

Guidance navigation and control technology for the lunar ascent vehicle of the Chang&amp;rsquo;e-5 mission

<p indent="0mm">The limitations of the remote control network and the lunar launch platform mean that many technologies differing from those of carrier rockets of the earth are required to transport samples from the hostile lunar environment. The Chang’e-5 mission uses some new techniques, such as the autonomous celestial positioning and orientating method, gravity measurement, and the adaptive powered explicit guidance algorithm, to improve the precision of entry into orbit. Furthermore, other techniques, including the fault diagnosis algorithm with threshold dynamic adjustment, thrust detection and reconstruction, non-interactive emergency guidance for ascent, and an autonomous orbit control strategy for salvage, are adopted to improve the safety of ascent from the lunar surface. These techniques enabled China to complete the moon launch successfully in the historic Lunar Sample Return mission.

Regolith Properties in the Chang'E‐5 Landing Region of the Moon: Results From Multi‐Source Remote Sensing Observations

AbstractIn December 2020, China's Chang'E‐5 (CE‐5) spacecraft successfully collected 1.731 kg samples from Oceanus Procellarum on the Moon's nearside, becoming the first lunar sample return mission since Luna 24 in 1976. These samples, collected from one of the youngest mare basalt units within the Procellarum KREEP Terrain, are critical to deciphering several fundamental questions of the Moon. In order to provide geologic context for interpreting the returned samples, we conducted a comprehensive analysis of regolith properties in the landing region using optical, topographic, multispectral, thermal, and radar observations. The CE‐5 landing site is within a flat, young mare basalt unit with intermediate titanium. A ballistic sedimentation model suggests that ∼98% of the surface regolith are local materials. The dielectric permittivity of the regolith is estimated to be 2.96 + i0.03 based on its composition and porosity. Morphologies of small fresh craters identified in high‐resolution optical images show that regolith thickness varies from ∼1.5 to ∼8 m with a median value of ∼5 m, implying a large mean regolith growth rate over the landing region. A comparison between radar image and Lunar Reconnaissance Orbiter Diviner surface rock abundance (RA) map indicates that subsurface rocks play a significant role in producing the observed radar backscatter. Further analysis of the radar echo suggests that subsurface RA is ∼0.47%–0.88% if the effective size is 3 cm, which can explain the shallow sampling depth of the CE‐5 drilling device. All these results provide valuable information for understanding the geological context and properties of the returned regolith samples.

Ground-test validation technologies for Chang&amp;rsquo;e-5 lunar probe

The complexity and particularity of Chang’e-5 unmanned lunar sample return missions have high demands for ground-test validation of the Chang’e-5 lunar probe. Test requirements cover multisystem levels, including the large-system, system, subsystem, and component levels. Several difficult ground tests are directed against the key processes, such as sampling and packaging, launching on the moon, rendezvous and docking, and sample transferring in lunar orbit, high-speed reentry. Here, we analyze the features of the ground-test validation for the Chang’e-5 lunar probe and the test requirements of each system level and highlight the testing systems, methods, and results of several large-scale comprehensive tests. Finally, we discuss the innovations of ground-test validation technologies for the Chang’e-5 lunar probe. This article provides important references and guidance for ground tests and design validation for future complex spacecraft or deep space probes.

Research of Reinforcement Deployment Mechanism of Automatic Sampler for Lunar Sample Return Mission

Chang’E-5 detector has successfully completed the lunar sample return mission, and accomplished the first extraterrestrial object drilling sampling detection of China. The deploying process is a key point for the whole mission and the design of the deployment mechanism is significantly important for the system. Compared to traditional deployment, low gravity surface operation and heavy load is the characteristics of this mission. In this paper, a design of reinforcement deployment mechanism suitable for lunar low gravity environment, large load condition is proposed. In this scheme, the planetary force augmentation and fulcrum separation method is adopted, the arm of force is introduced to achieve large load driving by small torque, and the design parameters are determined. The performance of the deployment mechanism is vindicated by dynamic simulation analysis and experimental verification. The research results demonstrate that the deployment mechanism can meet the demand of driving large load with small torque. The deployment mechanism designed based on this scheme has been employed by Chang’E-5 detector and performed perfectly on the moon.

Maria Basalts Chronology of the Chang’E-5 Sampling Site

Chang’E-5 is the first lunar sample return mission of China. The spacecraft was landed in the northwest of the Procellarum KREEP Terrane (43.0576°N, 308.0839°E) on 1 December 2020 and returned 1731 g samples from a previously unvisited region. The landing area has been proposed as one of the youngest mare basalt units of the Moon and holds important information of lunar thermal evolution and chronology. However, the absolute model ages estimated in previous studies are quite different, ranging from 2.07 Ga to 1.21 Ga. Such significant difference may be caused by (1) different crater counting areas, (2) different crater diameter ranges, (3) effects of secondary craters, and (4) biases in crater identification. Moreover, the accurate landing site was unknown and the ages were estimated over the Eratosthenian-aged mare unit (Em4) instead. In light of the above unsatisfactory conditions, this study seeks to establish a standard crater size-frequency distribution of the CE-5 landing site. We derived the concentrations of FeO and TiO2 to map out the pure basaltic areas where external ejecta deposits are negligible and thus secondary craters are rare. Based on the geochemistry of basaltic ejecta excavated by fresh craters in the mare unit, the FeO concentration threshold for mapping pure basaltic areas is 17.2 wt.%. The morphologically flat subunits in the pure basaltic areas were selected for crater identification and age dating to exclude the contamination of external ejecta to the best as we could. In the Chang’E-5 sampling site subunit, we detected 313 craters with a diameter greater than 100 m and derived the absolute model age as 1.49−0.084+0.084 Ga. The craters identified in all pure basaltic subunits of Em4 gave the model age of 1.41−0.028+0.027 Ga. As least affected by secondary craters, the crater size-frequency distribution of the sample-collected pure basaltic subunit can provide important constraints for lunar cratering chronology function in combination with isotopic age of returned samples.

Lunar Sample Return from Multiple Locations is a Critical Capability for Addressing High-Priority Planetary Science Goals

Lunar Sample Return from Multiple Locations is a Critical Capability for Addressing High-Priority Planetary Science Goals

China's Chang'e-5 landing site: Geology, stratigraphy, and provenance of materials

China's Chang'e-5 (CE-5) mission, the first lunar sample return mission since 1976, landed at 43.06°N, 51.92°W on Dec. 1, 2020, in Northern Oceanus Procellarum. CE-5 targeted a mare plain (Em4/P58) composed of distinctive young (∼1.6-1.7 Ga) moderate-Ti mare basalts, with elevated Th abundance (inherent or extraneous). Thus, the regolith and rock fragments sampled by CE-5 come from some of the youngest mare basalts on the Moon, near Rima Sharp, and from the center of the globally anomalous Procellarum KREEP Terrane (PKT), hypothesized to be responsible for the generation of the young volcanism. To provide context for the analysis and interpretation of the returned samples and in-situ measurements of the regolith substructure with penetrating radar, we constructed a detailed geologic map and stratigraphic assessment of the site. The stratigraphy consists of ancient highland materials (PKT crust and ejecta from Iridum and Imbrium basins), local silica-rich volcanism, overlain by a sequence of mare basalts, capped with Em4/P58. A ∼4-7 m thick regolith layer developed by post-mare bombardment overlies the Em4/P58 protolith and contains admixed impact ejecta from distant sources, mainly from Harpalus (∼6 wt.%), followed by Copernicus (∼2 wt.%) and Aristarchus (∼1 wt.%). New crater size-frequency measurements of Em4/P58 provide the necessary crater spatial density reference for calibration of the lunar cratering chronology with radiometric ages of the returned samples. The geological map and assessment of regolith provenance indicate that samples returned by CE-5 will address fundamental questions in lunar chronology, thermal evolution, basalt petrogenesis, and the nature of PKT, as well as provide key calibration for lunar and planetary chronologies and remote sensing data.

Young lunar mare basalts in the Chang'e-5 sample return region, northern Oceanus Procellarum

Chang'e-5, China's first lunar sample return mission, is targeted to land in northern Oceanus Procellarum, within a region selected on the basis of 1) its location away from the Apollo-Luna sampling region, 2) the presence of the Procellarum KREEP Terrane (PKT), 3) the occurrence of one of the youngest lunar mare basalts (Em4), and 4) its association with Rima Sharp. In order to provide context for returned sample analyses, we conducted a comprehensive study of the regional and global settings, geomorphology, composition, mineralogy, and chronology of the Em4 mare basalts. Superposed on Imbrian-aged low-Ti basalts, Em4 covers 37,000 km2 and is composed of Eratosthenian-aged (∼1.53 Ga), high-Ti basalts with a mean thickness of ∼51 m and a volume between ∼1450 and 2350 km3. Minor variations in TiO2 and FeO abundance occur within the unit and the thorium content averages ∼6.7 ppm, typical of PKT mare basaltic regolith. No specific source vents (e.g., fissures, cones, domes) were found within the unit. We show that Rima Sharp is actually composed of three major rilles, whose source vents are located outside of, and which flow into, and merge in Em4, suggesting that they may be among the sources for Em4. Regolith thickness averages ∼7 m and there is abundant evidence for vertical and lateral mixing; the most likely sources of distal ejecta are Aristarchus, Harpalus, and Sharp B craters. Returned samples from local and distant materials delivered by impact will thus provide significant new insights into lunar geochronology, inner Solar System impact fluxes, the age of very young mare basalts, the role of the PKT in the generation of mare basalts, the role of sinuous rilles in lava flow emplacement, and the thermal evolution of the Moon.

H2O and Other Volatiles in the Moon, 50 Years and on

In the fifty years since the first lunar sample return, the investigation of H2O in the Moon has experienced several stages of developments and paradigms. In the early years since Apollo sample ret...