Lunar Exploration Program Research Articles

A novel method measuring orifice conductance and testing time-of-flight mass spectrometer for water vapor–binary gas

Abstract The miniature time-of-flight mass spectrometer (TOF-MS) is a crucial instrument for detecting water ice in Chinese Lunar Exploration Program (CLEP), so it is necessary to compare its detection results for pure water vapor and water vapor-binary gas (such as H2O-N2, H2O-CH4, and H2O-Ar) to evaluate its water detection performance. The throughput must be calculated using the measured conductance to test the miniature TOF-MS. According to the VΔp method, the pΔt method, whose uncertainty is less than 14.2%, is proposed to measure orifice conductance for water vapor-binary gas, and an apparatus was developed based on those two methods. The orifice conductance of four kinds of pure gases (N2, H2O, CH4, and Ar) was measured using those two methods separately, and the measurement results allowed to calculate the conductance of the water vapor-binary gas through the Equivalent Single Gas method. The conductance of the water vapor-binary gas was measured using the pΔt method, and the difference between the calculated and measured results is less than 7%. Hence, the measured conductance allows the miniature TOF-MS to be tested for the water vapor-binary gas. As throughput is from 10-9 to 10-6 Pa m3 s-1, the difference between the test signals of water vapor-binary gas and pure water vapor is less than 40%.

Operational Tests for Delay-Tolerant Network between the Moon and Earth Using the Korea Pathfinder Lunar Orbiter in Lunar Orbit

The Korea Pathfinder Lunar Orbiter (KPLO) was launched on 5 August 2022, equipped on the SpaceX Falcon 9 launch vehicle. At present, the KPLO is effectively carrying out its scientific mission in lunar orbit. The KPLO serves as a cornerstone for the development and validation of Korean space science and deep space technology. Among its payloads is the DTNPL, enabling the first-ever test of delay-tolerant network (DTN) technology for satellites in lunar orbit. DTN technology represents a significant advancement in space communication, offering stable communication capabilities characterized by high delay tolerance, reliability, and asymmetric communication speeds—a necessity for existing satellite and space communication systems to evolve. In this paper, we briefly give an overview of the Korea Lunar Exploration Program (KLEP) and present scientific data gathered through the KPLO mission. Specifically, we focus on the operational tests for DTN-ION conducted for message and file transfer, as well as real-time video streaming, during the initial operations of the KPLO. Lastly, this study offers insights and lessons learned from KPLO DTNPL operations, with the goal of providing valuable guidance for future advancements in space communication.

Research on the Encapsulation Device for Lunar Samples

The encapsulation of lunar samples is a core research area in the third phase of the Chinese Lunar Exploration Program. The seal assembly, opening and closing mechanism (OCM), and locking mechanism are the core components of the encapsulation device of the lunar samples, and the requirements of a tight seal, lightweight, and low power make the design of these core components difficult. In this study, a combined sealing assembly, OCM, and locking mechanism were investigated for the device. The sealing architecture consists of rubber and an Ag-In alloy, and a theory was built to analyze the seal. Experiments of the electroplate Au coating on the knife-edge revealed that the hermetic seal can be significantly improved. The driving principle for coaxial double-helical pairs was investigated and used to design the OCM. Moreover, a locking mechanism was created using an electric initiating explosive device with orifice damping. By optimizing the design, the output parameters were adjusted to meet the requirements of the lunar explorer. The experimental results showed that the helium leak rate of the test pieces were not more than 5 × 10−11 Pa·m3·s−1, the minimum power of the OCM was 0.3 W, and the total weight of the principle prototype was 2.9 kg. The explosive driven locking mechanism has low impact. This investigation solved the difficulties in achieving tight seal, light weight, and low power for the lunar explorer, and the results can also be used to explore other extraterrestrial objects in the future.

Integrated Orbital Design Method for Manned Lunar Exploration with Relaxed Temporal Constraints

An integrated orbital design method with relaxation of temporal constraints is presented, focusing on improving the efficiency of complex-flight-mission planning for manned lunar exploration. Crewed lunar exploration programs are characterized by a variety of spacecraft and multiple trajectory stages. The aim of integrated design is to realize automatic splicing of such multistage trajectories under coupled temporal and spatial constraints. Currently, integrated mission–orbital design is mainly achieved through decoupling and iterative methods, and the matching of boundary constraints usually requires human-in-the-loop intervention. In this paper, a novel integrated orbital splicing process is proposed from the viewpoint of the temporal dimension, considering the temporal relationships between orbital stages and the scheduling flow of the underlying dynamical models. Relaxation factors are introduced for weak temporal constraints to improve the overall convergence of orbital splicing calculations across different stages. A comprehensive temporal constraint model and subsequently an integrated orbital design model are constructed. The proposed method is validated by simulation of flight missions targeting the high-latitude regions of the moon.

A New Method for Ground-Based Optical Polarization Observation of the Moon.

As a natural satellite of the Earth, the moon is a prime target for planetary remote sensing exploration. However, lunar polarization studies are not popular in the planetary science community. Polarimetry of the lunar surface had not been carried out from a spacecraft until the Korean lunar exploration program was initiated. In previous polarization observations of the moon, images of different polarization states were obtained by a rotating linear polarizer. This method is not well suited for future polarization observations from space-based spacecraft. To this end, we present a new kind of polarized observation of the moon using a division of a focal-plane polarization camera and propose a pipeline on the processing method of the polarization observation of the moon. We obtain a map of the degree of white-light polarization on the nearside of the moon through polarization observation, data processing, and correction. The observation and data processing methods presented in this study have the potential to serve as a reference for analyzing polarization observation data from future orbiting spacecraft. These are expected to lead to new discoveries in the fields of astronomy and planetary science.

Hierarchical Framework for Space Exploration Campaign Schedule Optimization

Space exploration plans are becoming increasingly complex as public agencies and private companies target deep-space locations, such as cislunar space and beyond, which require long-duration missions and many supporting systems and payloads. Optimizing multimission exploration campaigns is challenging due to the large number of required launches as well as their sequencing and compatibility requirements, making conventional space logistics formulations unscalable. To tackle this challenge, this paper proposes an alternative approach that leverages a two-level hierarchical optimization algorithm: an evolutionary algorithm is used to explore the campaign scheduling solution space, and each of the solutions is then evaluated using a time-expanded multicommodity flow mixed-integer linear program. A number of case studies, focusing on the Artemis lunar exploration program, demonstrate how the method can be used to analyze potential campaign architectures. The method enables a potential mission planner to study the sensitivity of a campaign to program-level parameters such as logistics vehicle availability and performance, payload launch windows, and in situ resource utilization infrastructure efficiency.

Distribution, Evolution, and Origin of the Lunar Energetic Particles

Various kinds of energetic particles can directly and continuously interact with the lunar surface since there is no atmosphere and no global magnetic field on the Moon. How energetic particles distribute on the Moon and what are their roles in the space weathering caused by the interactions between energetic particles and the lunar surface are the essential problems that need to be solved urgently in lunar science. In this paper, the research status and related scientific problems of the origin, distribution, and evolution of lunar energetic particles are summarized. The lunar exploration programs proposed by different countries and organizations are listed, and directions for future development are also discussed in this paper. Finally, based on the open questions and future focuses, we put forward several suggestions about China’s future lunar exploration programs and technical specifications of scientific payloads.

Scientific objectives and payload configuration of the Chang'E-7 mission.

As the cornerstone mission of the fourth phase of the Chinese Lunar Exploration Program, Chang'E-7 (CE-7) was officially approved, and implementation started in 2022, including a main probe and a communication relay satellite. The main probe, consisting of an orbiter, a lander, a rover and a mini-flying probe, is scheduled to be launched in 2026. The lander will land on Shackleton crater's illuminated rim near the lunar south pole, along with the rover and mini-flying probe. The relay satellite (named Queqiao-2) will be launched in February 2024 as an independent mission to support relay communication during scientific exploration undertaken by Chang'E-4, the upcoming Chang'E-6 in 2024 and subsequent lunar missions. The CE-7 mission is mainly aimed at scientific and resource exploration of the lunar south pole. We present CE-7's scientific objectives, the scientific payloads configuration and the main functions for each scientific payload with its key technical specifications.

Damage constitutive model of lunar soil simulant geopolymer under impact loading

Lunar base construction is a crucial component of the lunar exploration program, and considering the dynamic characteristics of lunar soil is important for moon construction. Therefore, investigating the dynamic properties of lunar soil by establishing a constitutive relationship is critical for providing a theoretical basis for its damage evolution. In this paper, a split Hopkinson pressure bar (SHPB) device was used to perform three sets of impact tests under different pressures on a lunar soil simulant geopolymer (LSSG) with sodium silicate (Na2SiO3) contents of 1%, 3%, 5% and 7%. The dynamic stress–strain curves, failure modes, and energy variation rules of LSSG under different pressures were obtained. The equation was modified based on the ZWT viscoelastic constitutive model and was combined with the damage variable. The damage element obeys the Weibull distribution and the constitutive equation that can describe the mechanical properties of LSSG under dynamic loading was obtained. The results demonstrate that the dynamic compressive strength of LSSG has a marked strain-rate strengthening effect. Na2SiO3 has both strengthening and deterioration effects on the dynamic compressive strength of LSSG. As Na2SiO3 grows, the dynamic compressive strength of LSSG first increases and then decreases. At a fixed air pressure, 5% Na2SiO3 had the largest dynamic compressive strength, the largest incident energy, the smallest absorbed energy, and the lightest damage. The ZWT equation was modified according to the stress response properties of LSSG and the range of the SHPB strain rate to obtain the constitutive equation of the LSSG, and the model's correctness was confirmed.

Yutu-2 Radar Observations at the Chang’E-4 Landing Site: The Shallow Geological Structure and Its Dielectric Properties

China has successfully carried out five lunar exploration missions since 2007. These missions indicate that China has successfully implemented a three-step lunar exploration program of “orbiting, landing, and returning”. Among them, the Lunar Penetrating Radar (LPR) carried by the Yutu-2 rover in the Chang’E-4 (CE-4) mission is the only one still operating on the far side of the Moon. Up to now, the Yutu-2 radar has measured a large amount of scientific data, and its observations are of great significance to human cognition of the geological evolution of the lunar surface and the exploration of possible lunar in situ resources. This paper reviews the scientific results obtained by previous researchers based on the radar exploration data of Yutu-2, focusing mainly on three aspects, e.g., the geological structure of the shallow surface at the CE-4 landing site, the dielectric properties of the shallow subsurface materials and the special geological features. Finally, the prospects of Yutu-2 radar research priorities and future exploration, and the application trend of Moon-based ground-penetrating radar are given.

Introduction to this special section: Planetary geophysics

While geophysical exploration of Earth is well established as a critical method for understanding planetary processes, many current and planned missions offer great opportunities for geophysicists to apply their skills and expertise to space exploration. Programs such as NASA's Artemis aiming to bring humans back to the moon and the James Webb Space Telescope for deep space imaging, the 10-year extension plan for the Chinese Lunar Exploration Program's Chang'e missions, the Japanese Aerospace Exploration Agency's Martian Moons eXploration program, and the European Space Agency's European Large Logistics Lander targeting the moon are just a few examples. NASA's Commercial Lunar Payload Services program proposes to send two commercial landers to the moon every year for the remainder of the decade. Several already-manifested payloads in the program involve geophysical instrumentation including heat flow probes, magnetotelluric sounding systems, and seismometers. Seismic data continue to arrive from NASA's InSight mission to Mars as the dusty solar panels still deliver a little energy, emphasizing that geophysics is and will remain an important tool for planetary exploration moving forward.

Toray goes lunar, wins awards for anti-thrombogenic innovation, and develops ion-conductive membrane, multilayer plastic tube, antiviral particles and super high barrier film

On July 20, Toray Carbon Magic Co., Ltd. announced that it will take part in the Hakuto-R commercial lunar exploration program operated by Tokyo-based ispace, inc. as a supporting company. Toray Carbon Magic has been utilizing the optimization design and weight reduction technologies that it cultivated in years of race car development to help develop a carbon fiber-reinforced airframe and parts for the program's lunar lander, rover, and other equipment.

Pulsed‐Laser‐Deposition Fabricated ZnIn2S4 Photodetectors with Excellent ON/OFF Switching Characteristics toward High‐Temperature‐Resistant Photodetection Applications

AbstractThe extensively explored unary and binary 2D layered materials (2DLMs) based photodetectors suffer from deficiencies of either poor stability, or indistinctive photoswitching, or poor scalability, or low durability to high‐temperature environment. Herein, a two‐step scenario, pulsed laser deposition (PLD) followed by post‐deposition annealing, is developed to produce centimeter‐scale 2D ZnIn2S4 (ZIS) nanofilms. Transport characterizations indicate that the as‐fabricated ZIS photodetectors manifest outstanding photosensitivity with an on/off switching ratio beyond 1000 upon 405 nm illumination. Beyond this, it is revealed that the photoresponse of the ZIS photodetectors increases with increasing channel thickness, where a responsivity of 1.4 A W−1, an external quantum efficiency of 430% and a detectivity of 9.8 × 109 Jones (1 Jones = 1 cm Hz1/2 W–1) are demonstrated with a pulse number of 10 000. In addition, these devices without encapsulation maintain stable within 1900 photoswitching cycles and over a one‐month storage in air. Furthermore, robust photoswitching is demonstrated under an operating temperature up to 150 °C. In summary, all these findings establish that PLD provides a powerful route to produce large‐scale multielement 2DLMs and the PLD‐derived ZIS photodetectors hold grand prospect for photoelectric technologies in specific high‐temperature environments (e.g., the lunar exploration program).

Development Trend of MBSE and Investigation of Concurrent Collaborative Demonstration for Chinese Lunar Exploration Program

Development Trend of MBSE and Investigation of Concurrent Collaborative Demonstration for Chinese Lunar Exploration Program

Temperature Correction and Result Evaluation of Lunar Mineralogical Spectrometer for Chang’E-5 Mission

The lunar mineralogical spectrometer (LMS) is the primary scientific payload of the Chang’E-5 mission of the China Lunar Exploration Program. The LMS is responsible for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> spectral detection and analysis of the sampling areas of interest on the Moon’s surface. The LMS needs to adapt to a wide range of temperature conditions, varying between the lunar morning to noon, based on the time, location, and work process of the LMS. Thus, ensuring consistency in the spectral data obtained at high temperatures and a wide range of operating environments is a major challenge. In this study, a thermal analysis model of the LMS is built, and the temperature variation of the LMS during its operation on the lunar surface is simulated using the instrument workflow that is based on the simulation results. Independent experiments were also carried out for the temperature-sensitive components in the LMS, and subsequently, the temperature correction model and model coefficients for each temperature-sensitive component were obtained. The final correction result was a quantitative assessment of the ground test data and the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> lunar detection data. For the ground tests at different temperatures, the average errors were found to be 0.57% and 1.2% for the short- and medium-wave data, respectively, after applying the temperature correction. When the LMS was operating on the lunar surface, the average errors for the short- and medium-ware data after the temperature correction were calculated to be 0.59% and 0.8%, respectively.

Orbit determination of China’s first mars probe Tianwen-1 during interplanetary cruise

Tianwen-1 is China’s first deep space probe to explore Mars with the goal of orbiting, landing and roving. This paper presents the orbit determination process and result of the probe in the phase of Earth-Mars trajectory in detail. Orbit determination is carried out based on the tracking data obtained by CDSN (Chinese Deep Space Network) and CVN (Chinese VLBI Network). The results show that the residual RMS of range, Doppler, VLBI delay and delay rate data are about 0.28 m, 0.10 mm/s, 0.12 ns and 0.34 ps/s, respectively. Compared with the previous missions in Chinese Lunar Exploration Program (CLEP), the accuracy of VLBI data is significantly improved. The analysis shows that the prediction error of EOP (Earth Orientation Parameter) and the planetary ephemerides lead to the difference of orbit solution. With the increasing distance between the spacecraft and Earth, the EOP prediction error has a certain influence to the orbit determination accuracy. The difference in orbit solutions due to EOPs’ prediction error before MOI (Mars Orbit Insertion) is about 300 m. Moreover, the orbit difference is about 200 m using different planetary ephemerides (DE421/DE436). Orbit overlapping results show the position and velocity error of Tianwen-1 are less than 2 km and 1 cm/s, respectively. During the approaching phase, the error ellipse in B-plane shows that σ SMAA = 389.40 m, σ SMIA = 140.88 m (1σ).

Lowering the barriers to lunar sourced propellant via competitive parity pricing

Recent remote sensing results and the current Artemis lunar exploration program have heightened interest in the potential for producing propellant on the lunar surface to contribute to the sustainability of ongoing activity in cislunar space. In this paper, we examine the case of lunar propellant competing against Earth-sourced propellant both on the lunar surface and in low lunar orbit. We restrict ourselves to providing lunar propellant for the purpose of landing cargo from low lunar orbit onto the lunar surface. In our analysis, we derive the revenue recoverable from, or value delivered by, lunar propellant by matching the cost of landing cargo using Earth-sourced propellant, rather than the cost of transporting propellant from Earth. We present the arguments in commercial and non-commercial contexts. We find that there are opportunities on the lunar surface for extracting value above the competing propellant transportation cost from Earth. When competing against Earth-sourced propellants in low lunar orbit, there are opportunities to extract more value than one could by supplying commodity propellants. The opportunities arise from expanding the factors contributing to competing costs, using combined cargo and propellant concepts of operations that deliver higher propellant efficiency, and from consolidating transportation assets with propellant supply to achieve higher capital efficiency. By using this analytical approach to transportation and transportation support services we were able to lower the barriers to the production and use of lunar sourced propellant.

Is There a Legal Path to Commercial Mining on the Moon?

The introduction describes how current lunar mining strengthens political incentives for commercial lunar activities. The present Chinese explorative excavation may bring greater clarity about the extent of commercial mining opportunities. It also raises issues regarding the lack of coordination between the lunar Artemis Program of the United States and the independent Chinese Lunar Exploration Program and raises uncertainties regarding the legal framework for lunar mining. Part I examines the fundamental law of the 1967 Outer Space Treaty (OST)&nbsp;regarding lunar mining. It briefly reviews the 1979 Moon Agreement,&nbsp;the Liability Convention,4 lunar environmental protection, peaceful uses, and applicable law of treaty interpretation. Part II discusses efforts to implement the OST in a way that makes mining on the Moon possible. It examines the Building Blocks for the Development of an International Framework on Space Resource Activities (Building Blocks Proposal),&nbsp;which results from a three-year international interagency, an interdisciplinary working group at the Institute of Air and Space Law, University of Leiden. Within the scope of existing space law, the working group prepared an extensive international framework for states to authorize and supervise space resource activities, including lunar mining by private companies. It proposes reasonable safety zones around each mining project. The Building Blocks Proposal is now before the United Nations Committee for the Peaceful Uses of Outer Space (COPUOS).&nbsp; Part II also describes the Artemis Accords,&nbsp;initiated by National Aeronautics Space Administration (NASA), an independent agency of the United States (U.S.).&nbsp;As of October 2021, twelve national space agencies have entered into bilateral accords with NASA to establish basic rules for lunar mining by commercial companies.&nbsp;The parties simply agree to respect each other’s lunar mining activities.&nbsp;Through the Artemis Accords, space agencies agree on operating rules for mining which include reasonable safety zones.&nbsp;Part II briefly discusses the Moon as a Commons as it affects lunar mining. It also examines possibilities for soft law regulation of lunar mining.&nbsp; The conclusion stresses the need for multilateral regulation of lunar mining. It urges COPUOS to adopt guidelines on lunar mining. It also recommends that the United States should eliminate the Wolf Amendment, which is a barrier to the coordination of lunar mining between the two space powers currently most active in lunar exploration and use.&nbsp;

“Spacecraft Thermal Control Technologies”

Into my hands came an exciting new book about space. “Spacecraft Thermal Control Technologies” is written by Professor Jianyin Miao, Qi Zhong, Professor Qiwei Zhao and Professor Xin Zhao. All the authors of this book are part of the Institute of Spacecraft System Engineering, China Academy of Space Technology (CAST), Beijing, China. Jianyin Miao is a head scientist of heat pipes at CAST and a Massachusetts Institute of Technology (MIT, USA) visiting professor, and is an academic leader for space thermal control technology at China Aerospace Science. Qi Zhong is a research fellow at CAST and his expertise is in the field of aerospace thermal control. Qiwei Zhao is a professor at CAST with expertise in the field of space thermophysics. Professor Xin Zhao has served as a chief designer of thermal control subsystems. He serves on the professional committee at CAST. He has received several national and ministerial awards for his work in this field. The series editor Peijian Ye, (China Academy of Space Technology, Beijing, China) is a Chinese aerospace engineer. He is a professor at the Beijing University of Aeronautics and Astronautics, China, and is a professor at the Harbin Institute of Technology, China. He is a research fellow and chief engineer at CAST. He is also the Chief Commander and Chief Designer of the Chinese Lunar Exploration Program. In his honour the inner main-belt asteroid 456677 Yepeijian, discovered by the Purple Mountain Observatory Near-Earth Object Survey Program at the XuYi Station, China, took his name in 2007.

General Scheme and Key Technology of Long March 5 Launch Vehicle

Long March 5 (LM-5) is a new generation of heavy-lift launch vehicle developed by China. It has successfully completed the first Mars exploration of China and the 3rd phase of China lunar exploration program of Chang’E 5 (CE-5). LM-5 experienced 30 years of key technology research and engineering development. During this period, a lot of engineering technical problems were conquered, rich experience in the development of large cryogenic launch vehicle was accumulated, and the development of the new generation launch vehicle system was constructed. The research capability and foundation of carrier rockets have been greatly improved. This paper describes the development background of LM-5. Based on the overall rocket technical scheme and technical innovation, this paper discusses the development thinking of the rocket, the modular configuration scheme, the overall optimization design technology of the whole rocket and the structure technology of the large diameter and large concentrated load rocket body, and probes into the key technical problems of the LM-5 for the deep space exploration mission, specifically, the orbit design and optimization technology for deep space exploration mission, and narrow window multi-orbit launch technology. LM-5 is a landmark project of China’s new generation of launch vehicle, representing the highest level of launch vehicle technology of China, and is a significant symbol for China’s transformation from a major player in space to major power in space.