To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in th...To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in the Solar System. Plate tectonics is a style of convection for an active planetoid where lid fragment(plate) motions reflect sinking of dense lithosphere in subduction zones, causing upwelling of asthenosphere at divergent plate boundaries and accompanied by focused upwellings, or mantle plumes;any other tectonic style is usefully called "stagnant lid" or "fragmented lid". In 2015 humanity completed a 50+ year effort to survey the 30 largest planets, asteroids, satellites, and inner Kuiper Belt objects,which we informally call "planetoids" and use especially images of these bodies to infer their tectonic activity. The four largest planetoids are enveloped in gas and ice(Jupiter, Saturn, Uranus, and Neptune)and are not considered. The other 26 planetoids range in mass over 5 orders of magnitude and in diameter over 2 orders of magnitude, from massive Earth down to tiny Proteus; these bodies also range widely in density, from 1000 to 5500 kg/m^3. A gap separates 8 silicate planetoids with ρ = 3000 kg/m^3 or greater from 20 icy planetoids(including the gaseous and icy giant planets) with ρ = 2200 kg/m^3 or less. We define the "Tectonic Activity Index"(TAI), scoring each body from 0 to 3 based on evidence for recent volcanism, deformation, and resurfacing(inferred from impact crater density). Nine planetoids with TAI = 2 or greater are interpreted to be tectonically and convectively active whereas 17 with TAI <2 are inferred to be tectonically dead. We further infer that active planetoids have lithospheres or icy shells overlying asthenosphere or water/weak ice. TAI of silicate(rocky) planetoids positively correlates with their inferred Rayleigh number. We conclude that some type of stagnant lid tectonics is the dominant mode of heat loss and that plate tectonics is unusual. To make progress understanding Earth's tectonic history and the tectonic style of active exoplanets, we need to better understand the range and controls of active stagnant lid tectonics.展开更多
Astronomers(天文学家)have discovered 128 new moons orbiting the planet Saturn.Now Saturn has 274 moons in total.Saturn holds the title“king of the moons”because it’s the planet with the most moons in our solar syst...Astronomers(天文学家)have discovered 128 new moons orbiting the planet Saturn.Now Saturn has 274 moons in total.Saturn holds the title“king of the moons”because it’s the planet with the most moons in our solar system(太阳系).Jupiter(木星)comes in second with 95 known moons.展开更多
The origin of rings is one of the final arguments in a series explaining solar system formation. Liquid moons placed in circular orbits close to the planet (inside the Roche limit) will deposit ring material as they m...The origin of rings is one of the final arguments in a series explaining solar system formation. Liquid moons placed in circular orbits close to the planet (inside the Roche limit) will deposit ring material as they migrate. Once outside the limit, moons retain this material. Finally, the shape of the moon, Pan, is explained, using the same mechanism that forms rings.展开更多
Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possib...Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possible generation mechanisms of the anomalies,we focus on magneto-convection and dynamos in the interiors via numerical simulation.To mimic the electromagnetic environment of the moons,we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field strength.Our results show that a finite B0 can substantially alter the dynamo processes inside the core.When the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action,the convective state in the core changes significantly:the convective flow decreases by 80% in magnitude,but the differential rotation becomes stronger in much of the fluid layer,leading to a stronger field generated in the core.The field morphologies inside the core tend to align with the ambient field,while the flow patterns show the symmetry-breaking effect under the influence of B0.Furthermore,the generated field tends to be temporally more stable.展开更多
Understanding the internal composition of a celestial body is fundamental for formulating theories regarding its origin.Deep knowledge of the distribution of mass under the body’s crust can be achieved by analyzing i...Understanding the internal composition of a celestial body is fundamental for formulating theories regarding its origin.Deep knowledge of the distribution of mass under the body’s crust can be achieved by analyzing its moments of inertia and gravity field.In this regard,the two moons of the Martian system have not yet been closely studied and continue to pose questions regarding their origin to the space community;thus,they deserve further characterization.The Martian Moons eXploration mission will be the first of its kind to sample and study Phobos over a prolonged period.This study aims to demonstrate that the adoption of periodic and quasi-periodic retrograde trajectories would be beneficial for the scientific value of the mission.Here,a covariance analysis was implemented to compare the estimation of high-order gravitational field coefficients from different orbital geometries and for different sets of processed observables.It was shown that the adoption of low-altitude non-planar quasi-satellite orbits would help to refine the knowledge of the moon’s libration angle and gravitational field.展开更多
1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of whe...1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of where it lies.2 Two probes are on their way to the Moon to solve this mystery.They will be launched on the same SpaceX Falcon 9 rocket from Cape Canaveral.If everything goes as planned,the first probe to reach the Moon will be Athena.Timothy Crain,the chief technology officer of Intuitive Machines,says it will take about 3 to 4 days,depending on the launch time.They'll orbit the Moon for 2 to 3 days to wait for the Sun to reach the landing site,because the lander's solar panels need sunlight to generate power.It only takes about 15 minutes to land softly after the engine is started.展开更多
The exploration of asteroids has received increasing attention since the 1990s because of the unique information these objects contain about the history of the early solar system.Quasi-satellites are a population of a...The exploration of asteroids has received increasing attention since the 1990s because of the unique information these objects contain about the history of the early solar system.Quasi-satellites are a population of asteroids that co-orbit closely with,but are outside the gravitational control of,the planet.So far,only five Earth quasi-satellites have been recognized,among which(469219)Kamo’oalewa(provisionally designated as 2016 HO3)is currently considered the most stable and the closest of these.However,little is known about this particular asteroid or this class of near-Earth asteroids because of the difficulties of observing them.China has announced that Tianwen-2,the asteroid sample-return mission to Kamo’oalewa,will be launched in 2025.Here,we review the current knowledge of Kamo’oalewa in terms of its physical characteristics,dynamic evolution,surface environment,and origin,and we propose possible breakthroughs that the samples could bring concerning the asteroid Kamo’oalewa as an Earth quasi-satellite.Confirming the origin of Kamo’oalewa,from its prevailing provenance as debris of the Moon,could be a promising start to inferring the evolutionary history of the Moon.This history would probably include a more comprehensive view of the lunar farside and the origin of the asymmetry between the two sides of the Moon.Comparing the samples from the Moon and Kamo’oalewa would also provide new insights into the Earth wind.展开更多
ITALY A crescent moon rises at sunset behind Monte Camicia in Teramo on 3 September US A dog rides the waves with its trainer during the 20th annual Surf Dog Surf-a-Thon in Del Mar,California,on 7 September.
Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,i...Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.展开更多
GREECE A full moon rises behind the Temple of Poseidon in Sounion on 10 July GERMANY Visitors attend the CosDay anime convention in Frankfurt on 5 July CROATIA A ceremonial parade is held at the 59th#akovo Embroidery ...GREECE A full moon rises behind the Temple of Poseidon in Sounion on 10 July GERMANY Visitors attend the CosDay anime convention in Frankfurt on 5 July CROATIA A ceremonial parade is held at the 59th#akovo Embroidery Festival in#akovo on 6 July。展开更多
Lunar wrinkle ridges are an important stress geological structure on the Moon, which reflect the stress state and geological activity on the Moon. They provide important insights into the evolution of the Moon and are...Lunar wrinkle ridges are an important stress geological structure on the Moon, which reflect the stress state and geological activity on the Moon. They provide important insights into the evolution of the Moon and are key factors influencing future lunar activity, such as the choice of landing sites. However, automatic extraction of lunar wrinkle ridges is a challenging task due to their complex morphology and ambiguous features. Traditional manual extraction methods are time-consuming and labor-intensive. To achieve automated and detailed detection of lunar wrinkle ridges, we have constructed a lunar wrinkle ridge data set, incorporating previously unused aspect data to provide edge information, and proposed a Dual-Branch Ridge Detection Network(DBR-Net) based on deep learning technology. This method employs a dual-branch architecture and an Attention Complementary Feature Fusion module to address the issue of insufficient lunar wrinkle ridge features. Through comparisons with the results of various deep learning approaches, it is demonstrated that the proposed method exhibits superior detection performance. Furthermore, the trained model was applied to lunar mare regions, generating a distribution map of lunar mare wrinkle ridges;a significant linear relationship between the length and area of the lunar wrinkle ridges was obtained through statistical analysis, and six previously unrecorded potential lunar wrinkle ridges were detected. The proposed method upgrades the automated extraction of lunar wrinkle ridges to a pixel-level precision and verifies the effectiveness of DBR-Net in lunar wrinkle ridge detection.展开更多
Profs.Yang Jun(杨军)and Hu Yongyun(胡永云)at the Department of Atmospheric and Oceanic Sciences,School of Physics,Peking University,and their collaborators recently published a paper in Nature Geoscience(http://www.na...Profs.Yang Jun(杨军)and Hu Yongyun(胡永云)at the Department of Atmospheric and Oceanic Sciences,School of Physics,Peking University,and their collaborators recently published a paper in Nature Geoscience(http://www.nature.com/ngeo/journal/v10/n8/pdf/ngeo2994.pdf).They show展开更多
Ownership is an increasingly important conflict in outer space at this moment in time.Despite the principle in the Outer Space Treaty(1967),that emphasizes the importance of all states'free access to outer space b...Ownership is an increasingly important conflict in outer space at this moment in time.Despite the principle in the Outer Space Treaty(1967),that emphasizes the importance of all states'free access to outer space based on equality for exploration and use.Moreover,outer space including the Moon and other celestial bodies is not subject to national appropriation by claim of sovereignty,by means of use or occupation,or by any other means.However,outer space activity is not free from sovereignty and jurisdiction after all.Anyway,the legal situation relating to space resource exploitation and utilization activities under the adoption of United Nations is a challenge.Some scholars implied that the Outer Space Treaty(1967)clearly prohibits appropriation of whole celestial bodies but is far less clear concerning the rights of over-extracted resources.Nevertheless,the Moon Agreement(1979)promotes the idea of property ownership of over-extracted resources.It permits states to collect and remove samples of lunar minerals and other substances for further interest in scientific investigation.The application of the Moon Agreement(1979)is not only to the Moon itself but to other celestial bodies,thus potentially covering the planets and asteroids where the mining potential is considered to be limitless.Under this circumstance,numerous countries,such as the United States,Luxembourg,The United Arab Emirates,and Japan have enacted legal regimes that glorify the rights of their entities in mineral resources in outer space.However,these regimes could be disputed under the international legal framework if countries have merely interpreted and applied their rights and obligations on a national level as they understand them.Therefore,this paper purports to clarify the ownership rights in outer space and analyze the purpose of the legal situation relating to space resource exploitation and utilization activities under the adoption of the United States,Luxembourg,The United Arab Emirates,and Japan.展开更多
我们可能在英语影视剧、文学作品中看到过一个短语叫“once in ablue moon”,这个短语用来描述很少发生的事件或情况,意味着某件事非常罕见,你可能很长时间都遇不到一次。例如,如果一个人偶尔玩一次游戏,你可以说他们“play games once ...我们可能在英语影视剧、文学作品中看到过一个短语叫“once in ablue moon”,这个短语用来描述很少发生的事件或情况,意味着某件事非常罕见,你可能很长时间都遇不到一次。例如,如果一个人偶尔玩一次游戏,你可以说他们“play games once in a blue moon”。展开更多
Amid the scarcity of lunar meteorites and the imperative to preserve their scientific value,nondestructive testing methods are essential.This translates into the application of microscale rock mechanics experiments an...Amid the scarcity of lunar meteorites and the imperative to preserve their scientific value,nondestructive testing methods are essential.This translates into the application of microscale rock mechanics experiments and scanning electron microscopy for surface composition analysis.This study explores the application of Machine Learning algorithms in predicting the mineralogical and mechanical properties of DHOFAR 1084,JAH 838,and NWA 11444 lunar meteorites based solely on their atomic percentage compositions.Leveraging a prior-data fitted network model,we achieved near-perfect classification scores for meteorites,mineral groups,and individual minerals.The regressor models,notably the KNeighbor model,provided an outstanding estimate of the mechanical properties—previously measured by nanoindentation tests—such as hardness,reduced Young’s modulus,and elastic recovery.Further considerations on the nature and physical properties of the minerals forming these meteorites,including porosity,crystal orientation,or shock degree,are essential for refining predictions.Our findings underscore the potential of Machine Learning in enhancing mineral identification and mechanical property estimation in lunar exploration,which pave the way for new advancements and quick assessments in extraterrestrial mineral mining,processing,and research.展开更多
Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct t...Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.展开更多
Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather cond...Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather conditions at the Lenghu site. The sky area is divided into rectangular regions, referred to as “tiles,” with a size of2°. 577 × 2°. 634 slightly smaller than the focal area of the mosaic CCDs. These tiles are continuously filled in annulars parallel to the equator. The brightness of the sky background, which varies with the moon phase and distance from the moon, plays a significant role in determining the accessible survey fields. Approximately 50connected tiles are grouped into one block for observation. To optimize the survey schedule, we perform simulations by taking into account the length of exposures, data readout, telescope slewing, and all relevant observing conditions. We utilize the Greedy Algorithm for scheduling optimization. Additionally, we propose a dedicated dithering pattern to cover the gaps between CCDs and the four corners of the mosaic CCD array, which are located outside of the 3° field of view. This dithering pattern helps to achieve relatively uniform exposure maps for the final survey outputs.展开更多
The Last Quarter of the Moon is a novel written by Chi Zijian,which describes the life of the Ewenki ethnic minority in northeast China.The novel has received wide attention for its profound theme and unique narrative...The Last Quarter of the Moon is a novel written by Chi Zijian,which describes the life of the Ewenki ethnic minority in northeast China.The novel has received wide attention for its profound theme and unique narrative style.Defamiliarization is a technique commonly used in literary creation.By breaking the conventional expression mode and changing the conventional view,readers can have new feelings and understandings.The original text of The Last Quarter of the Moon describes the life of the Ewenki minority in China,which has a strong defamiliarization effect.In the English version,the translator adopts various methods to reproduce this defamiliarization.Through the analysis of its English translation,this paper discusses the defamiliarization embodied in it and the two translation methods used by the translator to reproduce the defamiliarization of the original text:alienizing translation and hybridization.It is found that the translation successfully retains the unique charm of the original text by means of language and cultural defamiliarization,enabling English readers to obtain a new reading experience,and revealing the important reasons why the English translation of The Last Quarter of the Moon can be successfully translated and spread in the Western world.展开更多
基金supported by SNSF grant IZKOZ-2_154380partly supported by SNF 200021_149252
文摘To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in the Solar System. Plate tectonics is a style of convection for an active planetoid where lid fragment(plate) motions reflect sinking of dense lithosphere in subduction zones, causing upwelling of asthenosphere at divergent plate boundaries and accompanied by focused upwellings, or mantle plumes;any other tectonic style is usefully called "stagnant lid" or "fragmented lid". In 2015 humanity completed a 50+ year effort to survey the 30 largest planets, asteroids, satellites, and inner Kuiper Belt objects,which we informally call "planetoids" and use especially images of these bodies to infer their tectonic activity. The four largest planetoids are enveloped in gas and ice(Jupiter, Saturn, Uranus, and Neptune)and are not considered. The other 26 planetoids range in mass over 5 orders of magnitude and in diameter over 2 orders of magnitude, from massive Earth down to tiny Proteus; these bodies also range widely in density, from 1000 to 5500 kg/m^3. A gap separates 8 silicate planetoids with ρ = 3000 kg/m^3 or greater from 20 icy planetoids(including the gaseous and icy giant planets) with ρ = 2200 kg/m^3 or less. We define the "Tectonic Activity Index"(TAI), scoring each body from 0 to 3 based on evidence for recent volcanism, deformation, and resurfacing(inferred from impact crater density). Nine planetoids with TAI = 2 or greater are interpreted to be tectonically and convectively active whereas 17 with TAI <2 are inferred to be tectonically dead. We further infer that active planetoids have lithospheres or icy shells overlying asthenosphere or water/weak ice. TAI of silicate(rocky) planetoids positively correlates with their inferred Rayleigh number. We conclude that some type of stagnant lid tectonics is the dominant mode of heat loss and that plate tectonics is unusual. To make progress understanding Earth's tectonic history and the tectonic style of active exoplanets, we need to better understand the range and controls of active stagnant lid tectonics.
文摘Astronomers(天文学家)have discovered 128 new moons orbiting the planet Saturn.Now Saturn has 274 moons in total.Saturn holds the title“king of the moons”because it’s the planet with the most moons in our solar system(太阳系).Jupiter(木星)comes in second with 95 known moons.
文摘The origin of rings is one of the final arguments in a series explaining solar system formation. Liquid moons placed in circular orbits close to the planet (inside the Roche limit) will deposit ring material as they migrate. Once outside the limit, moons retain this material. Finally, the shape of the moon, Pan, is explained, using the same mechanism that forms rings.
基金supported by National Natural Science Foundation of China (Grant No. 40328006)
文摘Galileo mission detected the magnetic anomalies originated from Galilean moons.These anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian field.Among various possible generation mechanisms of the anomalies,we focus on magneto-convection and dynamos in the interiors via numerical simulation.To mimic the electromagnetic environment of the moons,we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field strength.Our results show that a finite B0 can substantially alter the dynamo processes inside the core.When the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action,the convective state in the core changes significantly:the convective flow decreases by 80% in magnitude,but the differential rotation becomes stronger in much of the fluid layer,leading to a stronger field generated in the core.The field morphologies inside the core tend to align with the ambient field,while the flow patterns show the symmetry-breaking effect under the influence of B0.Furthermore,the generated field tends to be temporally more stable.
基金This research was partially funded by CNES under the research contract Ref.R-S20/BS-0005-069.
文摘Understanding the internal composition of a celestial body is fundamental for formulating theories regarding its origin.Deep knowledge of the distribution of mass under the body’s crust can be achieved by analyzing its moments of inertia and gravity field.In this regard,the two moons of the Martian system have not yet been closely studied and continue to pose questions regarding their origin to the space community;thus,they deserve further characterization.The Martian Moons eXploration mission will be the first of its kind to sample and study Phobos over a prolonged period.This study aims to demonstrate that the adoption of periodic and quasi-periodic retrograde trajectories would be beneficial for the scientific value of the mission.Here,a covariance analysis was implemented to compare the estimation of high-order gravitational field coefficients from different orbital geometries and for different sets of processed observables.It was shown that the adoption of low-altitude non-planar quasi-satellite orbits would help to refine the knowledge of the moon’s libration angle and gravitational field.
文摘1 If astronauts want to stay on the Moon for more than a few days,they must find local resources,and water is one of the most crucial ones.Scientists believe there's water on the Moon,but they're unsure of where it lies.2 Two probes are on their way to the Moon to solve this mystery.They will be launched on the same SpaceX Falcon 9 rocket from Cape Canaveral.If everything goes as planned,the first probe to reach the Moon will be Athena.Timothy Crain,the chief technology officer of Intuitive Machines,says it will take about 3 to 4 days,depending on the launch time.They'll orbit the Moon for 2 to 3 days to wait for the Sun to reach the landing site,because the lander's solar panels need sunlight to generate power.It only takes about 15 minutes to land softly after the engine is started.
基金supported by the National Natural Science Foundation of China(Grant Nos.42241106 and 42388101).
文摘The exploration of asteroids has received increasing attention since the 1990s because of the unique information these objects contain about the history of the early solar system.Quasi-satellites are a population of asteroids that co-orbit closely with,but are outside the gravitational control of,the planet.So far,only five Earth quasi-satellites have been recognized,among which(469219)Kamo’oalewa(provisionally designated as 2016 HO3)is currently considered the most stable and the closest of these.However,little is known about this particular asteroid or this class of near-Earth asteroids because of the difficulties of observing them.China has announced that Tianwen-2,the asteroid sample-return mission to Kamo’oalewa,will be launched in 2025.Here,we review the current knowledge of Kamo’oalewa in terms of its physical characteristics,dynamic evolution,surface environment,and origin,and we propose possible breakthroughs that the samples could bring concerning the asteroid Kamo’oalewa as an Earth quasi-satellite.Confirming the origin of Kamo’oalewa,from its prevailing provenance as debris of the Moon,could be a promising start to inferring the evolutionary history of the Moon.This history would probably include a more comprehensive view of the lunar farside and the origin of the asymmetry between the two sides of the Moon.Comparing the samples from the Moon and Kamo’oalewa would also provide new insights into the Earth wind.
文摘ITALY A crescent moon rises at sunset behind Monte Camicia in Teramo on 3 September US A dog rides the waves with its trainer during the 20th annual Surf Dog Surf-a-Thon in Del Mar,California,on 7 September.
基金support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB 41000000(Y.L.)+4 种基金National Natural Science Foundation of China(Nos.42273042 and 41931077)"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(DHSZZ2023-3)Guizhou Provincial Foundation for Excellent Scholars Program(No.GCC[2023]088)Guizhou Provincial Science and Technology Projects:QKHJCZK[2023]-General 473NSFC Young Scientist Fund(Nos.42303041 and 42403043)。
文摘Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.
文摘GREECE A full moon rises behind the Temple of Poseidon in Sounion on 10 July GERMANY Visitors attend the CosDay anime convention in Frankfurt on 5 July CROATIA A ceremonial parade is held at the 59th#akovo Embroidery Festival in#akovo on 6 July。
文摘Lunar wrinkle ridges are an important stress geological structure on the Moon, which reflect the stress state and geological activity on the Moon. They provide important insights into the evolution of the Moon and are key factors influencing future lunar activity, such as the choice of landing sites. However, automatic extraction of lunar wrinkle ridges is a challenging task due to their complex morphology and ambiguous features. Traditional manual extraction methods are time-consuming and labor-intensive. To achieve automated and detailed detection of lunar wrinkle ridges, we have constructed a lunar wrinkle ridge data set, incorporating previously unused aspect data to provide edge information, and proposed a Dual-Branch Ridge Detection Network(DBR-Net) based on deep learning technology. This method employs a dual-branch architecture and an Attention Complementary Feature Fusion module to address the issue of insufficient lunar wrinkle ridge features. Through comparisons with the results of various deep learning approaches, it is demonstrated that the proposed method exhibits superior detection performance. Furthermore, the trained model was applied to lunar mare regions, generating a distribution map of lunar mare wrinkle ridges;a significant linear relationship between the length and area of the lunar wrinkle ridges was obtained through statistical analysis, and six previously unrecorded potential lunar wrinkle ridges were detected. The proposed method upgrades the automated extraction of lunar wrinkle ridges to a pixel-level precision and verifies the effectiveness of DBR-Net in lunar wrinkle ridge detection.
文摘Profs.Yang Jun(杨军)and Hu Yongyun(胡永云)at the Department of Atmospheric and Oceanic Sciences,School of Physics,Peking University,and their collaborators recently published a paper in Nature Geoscience(http://www.nature.com/ngeo/journal/v10/n8/pdf/ngeo2994.pdf).They show
文摘Ownership is an increasingly important conflict in outer space at this moment in time.Despite the principle in the Outer Space Treaty(1967),that emphasizes the importance of all states'free access to outer space based on equality for exploration and use.Moreover,outer space including the Moon and other celestial bodies is not subject to national appropriation by claim of sovereignty,by means of use or occupation,or by any other means.However,outer space activity is not free from sovereignty and jurisdiction after all.Anyway,the legal situation relating to space resource exploitation and utilization activities under the adoption of United Nations is a challenge.Some scholars implied that the Outer Space Treaty(1967)clearly prohibits appropriation of whole celestial bodies but is far less clear concerning the rights of over-extracted resources.Nevertheless,the Moon Agreement(1979)promotes the idea of property ownership of over-extracted resources.It permits states to collect and remove samples of lunar minerals and other substances for further interest in scientific investigation.The application of the Moon Agreement(1979)is not only to the Moon itself but to other celestial bodies,thus potentially covering the planets and asteroids where the mining potential is considered to be limitless.Under this circumstance,numerous countries,such as the United States,Luxembourg,The United Arab Emirates,and Japan have enacted legal regimes that glorify the rights of their entities in mineral resources in outer space.However,these regimes could be disputed under the international legal framework if countries have merely interpreted and applied their rights and obligations on a national level as they understand them.Therefore,this paper purports to clarify the ownership rights in outer space and analyze the purpose of the legal situation relating to space resource exploitation and utilization activities under the adoption of the United States,Luxembourg,The United Arab Emirates,and Japan.
基金EP-A and JMT-R acknowledges financial support from the project PID2021-128062NB-I00 funded by MCIN/AEI/10.13039/501100011033The lunar samples studied here were acquired in the framework of grant PGC2018-097374-B-I00(P.I.JMT-R)+3 种基金This project has received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(No.865657)for the project“Quantum Chemistry on Interstellar Grains”(QUANTUMGRAIN),AR acknowledges financial support from the FEDER/Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación(No.PID2021-126427NB-I00)Partial financial support from the Spanish Government(No.PID2020-116844RB-C21)the Generalitat de Catalunya(No.2021-SGR-00651)is acknowledgedThis work was supported by the LUMIO project funded by the Agenzia Spaziale Italiana(No.2024-6-HH.0).
文摘Amid the scarcity of lunar meteorites and the imperative to preserve their scientific value,nondestructive testing methods are essential.This translates into the application of microscale rock mechanics experiments and scanning electron microscopy for surface composition analysis.This study explores the application of Machine Learning algorithms in predicting the mineralogical and mechanical properties of DHOFAR 1084,JAH 838,and NWA 11444 lunar meteorites based solely on their atomic percentage compositions.Leveraging a prior-data fitted network model,we achieved near-perfect classification scores for meteorites,mineral groups,and individual minerals.The regressor models,notably the KNeighbor model,provided an outstanding estimate of the mechanical properties—previously measured by nanoindentation tests—such as hardness,reduced Young’s modulus,and elastic recovery.Further considerations on the nature and physical properties of the minerals forming these meteorites,including porosity,crystal orientation,or shock degree,are essential for refining predictions.Our findings underscore the potential of Machine Learning in enhancing mineral identification and mechanical property estimation in lunar exploration,which pave the way for new advancements and quick assessments in extraterrestrial mineral mining,processing,and research.
基金supported by the National Key Research and Development Program of China(2021YFA0715101)partly supported by a National LLR station project+2 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.11973064 and 42101413)Jilin Province Mid-youth science and technology innovation and entrepreneurship outstanding talent project(20220508147RC)the Changchun City and Chinese Academy of Sciences Science and Technology Cooperation High-tech Industrialization Special Fund Project(21SH05)。
文摘Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.
基金supported by the National Natural Science Foundation of China (12233005, 12073078 and 12173088)the science research grants from the China Manned Space Project with NO. CMS-CSST-2021-A02, CMS-CSST-2021-A04 and CMS-CSST-2021-A07grants from the Cyrus Chun Ying Tang Foundations。
文摘Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather conditions at the Lenghu site. The sky area is divided into rectangular regions, referred to as “tiles,” with a size of2°. 577 × 2°. 634 slightly smaller than the focal area of the mosaic CCDs. These tiles are continuously filled in annulars parallel to the equator. The brightness of the sky background, which varies with the moon phase and distance from the moon, plays a significant role in determining the accessible survey fields. Approximately 50connected tiles are grouped into one block for observation. To optimize the survey schedule, we perform simulations by taking into account the length of exposures, data readout, telescope slewing, and all relevant observing conditions. We utilize the Greedy Algorithm for scheduling optimization. Additionally, we propose a dedicated dithering pattern to cover the gaps between CCDs and the four corners of the mosaic CCD array, which are located outside of the 3° field of view. This dithering pattern helps to achieve relatively uniform exposure maps for the final survey outputs.
基金The study reported here was supported by the Zhejiang Social Science Planning Project(Fund No.22NDJC046YB).
文摘The Last Quarter of the Moon is a novel written by Chi Zijian,which describes the life of the Ewenki ethnic minority in northeast China.The novel has received wide attention for its profound theme and unique narrative style.Defamiliarization is a technique commonly used in literary creation.By breaking the conventional expression mode and changing the conventional view,readers can have new feelings and understandings.The original text of The Last Quarter of the Moon describes the life of the Ewenki minority in China,which has a strong defamiliarization effect.In the English version,the translator adopts various methods to reproduce this defamiliarization.Through the analysis of its English translation,this paper discusses the defamiliarization embodied in it and the two translation methods used by the translator to reproduce the defamiliarization of the original text:alienizing translation and hybridization.It is found that the translation successfully retains the unique charm of the original text by means of language and cultural defamiliarization,enabling English readers to obtain a new reading experience,and revealing the important reasons why the English translation of The Last Quarter of the Moon can be successfully translated and spread in the Western world.
