The cryosphere component provides the most reliable and insightful indications of any planet’s climate dynamics.Using data from the Compact Reconnaissance Imaging Spectrometer for Mars(CRISM),we develop a novel appro...The cryosphere component provides the most reliable and insightful indications of any planet’s climate dynamics.Using data from the Compact Reconnaissance Imaging Spectrometer for Mars(CRISM),we develop a novel approach to determining the broadband Visible and Near Infrared(VNIR)albedo of the Martian surface.This study focuses on albedo changes in the McMurdo crater,part of Mars’s south polar layer deposits.We compare seasonal and interannual variations of the McMurdo surface albedo before,during,and after the Global Dust Storm(GDS)of Martian Year(MY)34.As the seasons progressed from spring to summer,the mean albedo in MY 32 and 34 plunged by over 40%,by about 35%in MY 33,and by slightly more than 30%in MY 35.Compared interannually,however,mean albedo values within both seasons(spring and summer)exhibited no significant differences in those same years.Notably,interannual albedo difference maps reveal albedo variation of more than±0.3 in certain regions of the crater.Considering only snow-covered pixels,interannual albedo differences suggest that Mars dust had a pervasive impact on Mars’s cryosphere.Variations in maximum and minimum albedo values as high as 0.5 were observed,depending upon differences in the dust levels in Martian snow/ice.The maximum and the minimum snow albedo values were lowest in MY 34,indicating the effect of the intense dust storm event that year.The average snow albedo decreased from 0.45 in MY 32 to 0.40 in MY 33 and to 0.33 in MY 34,and then rose back to 0.40 in MY 35.This trajectory suggests a temporary deposition of dust,partially reversed after the GDS by self-cleaning mechanisms(local aeolian process and CO_(2)sublimation/deposition cycle).展开更多
Internal gravity waves(IGWs)are critical in driving Martian atmospheric motion and phenomena.This study investigates Martian IGWs by using high-resolution data from China’s Tianwen-1 mission and the National Aeronaut...Internal gravity waves(IGWs)are critical in driving Martian atmospheric motion and phenomena.This study investigates Martian IGWs by using high-resolution data from China’s Tianwen-1 mission and the National Aeronautics and Space Administration’s Mars Global Surveyor(MGS)by the radio occultation(RO)technique.Key IGW parameters,such as vertical and horizontal wavelengths,intrinsic frequency,and energy density,are extracted based on vertical temperature profiles from the Martian surface to~50 km altitude.Data reveal that the Martian IGWs are predominantly small-scale waves,with vertical wavelengths between 6 and 13 km and horizontal wavelengths extending to thousands of kilometers.These waves propagate almost vertically and exhibit low intrinsic frequencies close to the inertial frequency,with the characteristic of low-frequency inertial IGWs.Tianwen-1 data indicate stronger IGW activity,higher energy density,and less dissipation than MGS data in the northern hemisphere.Moreover,MGS data in the southern hemisphere show higher buoyancy frequencies and lower vertical wavelengths,suggesting more stable atmospheric conditions conducive to IGW propagation.These extracted IGW characteristics can enhance our understanding of the atmospheric dynamics on Mars and contribute valuable information for parameterization in global circulation models.展开更多
Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosi...Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.展开更多
With the development of the hyperspectral remote sensing technique,extensive chemical weathering profiles have been identified on Mars.These weathering sequences,formed through precipitation-driven leaching processes,...With the development of the hyperspectral remote sensing technique,extensive chemical weathering profiles have been identified on Mars.These weathering sequences,formed through precipitation-driven leaching processes,can reflect the paleoenvironments and paleoclimates during pedogenic processes.The specific composition and stratigraphic profiles mirror the mineralogical and chemical trends observed in weathered basalts on Hainan Island in south China.In this study,we investigated the laboratory reflectance spectra of a 53-m-long drilling core of a thick basaltic weathering profile collected from Hainan Island.We established a quantitative spectral model by combining the genetic algorithm and partial least squares regression(GA-PLSR)to predict the chemical properties(SiO2,Al2O3,Fe2O3)and index of laterization(IOL).The entire sample set was divided into a calibration set of 25 samples and a validation set of 12 samples.Specifically,the GA was used to select the spectral subsets for each composition,which were then input into the PLSR model to derive the chemical concentration.The coefficient of determination(R2)values on the validation set for SiO2,Al2O3,Fe2O3,and the IOL were greater than 0.9.In addition,the effects of various spectral preprocessing techniques on the model accuracy were evaluated.We found that the spectral derivative treatment boosted the prediction accuracy of the GA-PLSR model.The improvement achieved with the second derivative was more pronounced than when using the first derivative.The quantitative model developed in this work has the potential to estimate the contents of similar weathering basalt products,and thus infer the degree of alteration and provide insights into paleoclimatic conditions.Moreover,the informative bands selected by the GA can serve as a guideline for designing spectral channels for the next generation of spectrometers.展开更多
The InSight(Interior Exploration using Seismic Investigations,Geodesy,and Heat Transport)mission has recorded continuous ambient noise signals with many spectral peaks since its landing in 2018.The majority of these p...The InSight(Interior Exploration using Seismic Investigations,Geodesy,and Heat Transport)mission has recorded continuous ambient noise signals with many spectral peaks since its landing in 2018.The majority of these peaks are modes produced by instrumental vibrations and are associated with environmental factors,such as temperature and wind energy fluctuations.Understanding how these modes react under various conditions is crucial because it aids in identifying their origins.In this study,we analyzed the three-component spectra of InSight recordings from sols 184–738 and obtained the horizontal-to-vertical spectral ratio(HVSR,also known as H/V)curves for different time intervals.The primary modes,such as those at 3.3 and 4.1 Hz,exhibited different behaviors,suggesting diverse origins.Some modes were sensitive to low temperature and some were sensitive to high temperature.Additionally,we investigated the influence of wind and temperature on the H/V curve.The peak frequency was mainly affected by temperature,whereas the H/V value was not associated with the temperature or wind only.Characterizing these modes and elucidating their origins are significant for processing signals from InSight and can provide valuable guidance for designing future planetary seismometers.展开更多
For planetary surface materials,thermal inertia is the critical property that governs the surface’s daily thermal response and controls diurnal and seasonal surface temperature variations.Here we use the ground measu...For planetary surface materials,thermal inertia is the critical property that governs the surface’s daily thermal response and controls diurnal and seasonal surface temperature variations.Here we use the ground measurements made by the MSL Curiosity rover and the InSight lander to determine the thermal inertia of two sites on Mars.This study compares the variation of thermal inertia during and after the Large Dust Storm(LDS)of Martian Year(MY)34.To determine surface thermal inertia,we derive a simple approximation(using energy balance),which utilizes surface albedo,surface energy flux,and diurnal change in the surface temperature.The average thermal inertia in MY34 is about 39.2%,3.7%,and 3.4%higher than MY35 average thermal inertia for the MSL,InSight(FOV1),and InSight(FOV2),respectively.Notably,the thermal inertia at the InSight(FOV1)is consistently lower by about 20 J·m^(-2)·s^(-1/2)·K^(-1) than the InSight(FOV2)site for all scenarios,indicating variation in the region’s surface composition.The best-fit surface albedo in MY34(determined using the KRC model)are about 0.08,0.05,and 0.03 higher than MY35 surface albedo for the MSL,InSight(FOV1),and InSight(FOV2),respectively.An increase in both surface albedo and thermal inertia during the LDS indicates that the underlying surface is both more thermally resistant and more reflective than the overlying loose dust.展开更多
This review article aims to gather differences and similarities between planet Mars and planet Earth to determine the necessities for the proper growth and development of the neonatal brain. Factors such as Environmen...This review article aims to gather differences and similarities between planet Mars and planet Earth to determine the necessities for the proper growth and development of the neonatal brain. Factors such as Environmental, Nutritional, Social, Stress, and Education are juxtaposed to understand the difference between pediatric neurodevelopment on both planets. The variation between each factor was analyzed to determine how significant the impact is on neurodevelopment for children. The factors to be discussed were generated based on extensive research on what is most important for proper early neurodevelopment. The five factors are the main categories branched out into subcategories to delve into more detail regarding neurodevelopment. Factors may vary based on the location on each planet, but the best average was cultivated to create a fair evaluation of the differences. Although each factor influences a different part of the brain, each factor (Environmental, Nutritional, Social, Stress, and Education) is equally vital for development anatomy and physiology of the brain.展开更多
基金support from the Indian Institute of Technology Bombay (IITB) for providing the necessary facility and IITB seed grant.
文摘The cryosphere component provides the most reliable and insightful indications of any planet’s climate dynamics.Using data from the Compact Reconnaissance Imaging Spectrometer for Mars(CRISM),we develop a novel approach to determining the broadband Visible and Near Infrared(VNIR)albedo of the Martian surface.This study focuses on albedo changes in the McMurdo crater,part of Mars’s south polar layer deposits.We compare seasonal and interannual variations of the McMurdo surface albedo before,during,and after the Global Dust Storm(GDS)of Martian Year(MY)34.As the seasons progressed from spring to summer,the mean albedo in MY 32 and 34 plunged by over 40%,by about 35%in MY 33,and by slightly more than 30%in MY 35.Compared interannually,however,mean albedo values within both seasons(spring and summer)exhibited no significant differences in those same years.Notably,interannual albedo difference maps reveal albedo variation of more than±0.3 in certain regions of the crater.Considering only snow-covered pixels,interannual albedo differences suggest that Mars dust had a pervasive impact on Mars’s cryosphere.Variations in maximum and minimum albedo values as high as 0.5 were observed,depending upon differences in the dust levels in Martian snow/ice.The maximum and the minimum snow albedo values were lowest in MY 34,indicating the effect of the intense dust storm event that year.The average snow albedo decreased from 0.45 in MY 32 to 0.40 in MY 33 and to 0.33 in MY 34,and then rose back to 0.40 in MY 35.This trajectory suggests a temporary deposition of dust,partially reversed after the GDS by self-cleaning mechanisms(local aeolian process and CO_(2)sublimation/deposition cycle).
基金National Natural Science Foundation of China(Grant Nos.42174192,12241101,and 91952111).
文摘Internal gravity waves(IGWs)are critical in driving Martian atmospheric motion and phenomena.This study investigates Martian IGWs by using high-resolution data from China’s Tianwen-1 mission and the National Aeronautics and Space Administration’s Mars Global Surveyor(MGS)by the radio occultation(RO)technique.Key IGW parameters,such as vertical and horizontal wavelengths,intrinsic frequency,and energy density,are extracted based on vertical temperature profiles from the Martian surface to~50 km altitude.Data reveal that the Martian IGWs are predominantly small-scale waves,with vertical wavelengths between 6 and 13 km and horizontal wavelengths extending to thousands of kilometers.These waves propagate almost vertically and exhibit low intrinsic frequencies close to the inertial frequency,with the characteristic of low-frequency inertial IGWs.Tianwen-1 data indicate stronger IGW activity,higher energy density,and less dissipation than MGS data in the northern hemisphere.Moreover,MGS data in the southern hemisphere show higher buoyancy frequencies and lower vertical wavelengths,suggesting more stable atmospheric conditions conducive to IGW propagation.These extracted IGW characteristics can enhance our understanding of the atmospheric dynamics on Mars and contribute valuable information for parameterization in global circulation models.
基金EES acknowledges funding from a NERC Frontiers grant(NE/V010824/1)Leverhulme Trust research grant(RPG-2022-313).
文摘Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.
基金National Key Research and Development Project(Grant No.2019YFE0123300)National Natural Science Foundation of China(Grant Nos.42072337,42241111,and 42241129)+1 种基金Pandeng Program of National Space Science Center,Chinese Academy of Sciences.Xing Wu also acknowledges support from the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(Grant No.2022QNRC001)China Postdoctoral Science Foundation(Grant No.2021M700149).
文摘With the development of the hyperspectral remote sensing technique,extensive chemical weathering profiles have been identified on Mars.These weathering sequences,formed through precipitation-driven leaching processes,can reflect the paleoenvironments and paleoclimates during pedogenic processes.The specific composition and stratigraphic profiles mirror the mineralogical and chemical trends observed in weathered basalts on Hainan Island in south China.In this study,we investigated the laboratory reflectance spectra of a 53-m-long drilling core of a thick basaltic weathering profile collected from Hainan Island.We established a quantitative spectral model by combining the genetic algorithm and partial least squares regression(GA-PLSR)to predict the chemical properties(SiO2,Al2O3,Fe2O3)and index of laterization(IOL).The entire sample set was divided into a calibration set of 25 samples and a validation set of 12 samples.Specifically,the GA was used to select the spectral subsets for each composition,which were then input into the PLSR model to derive the chemical concentration.The coefficient of determination(R2)values on the validation set for SiO2,Al2O3,Fe2O3,and the IOL were greater than 0.9.In addition,the effects of various spectral preprocessing techniques on the model accuracy were evaluated.We found that the spectral derivative treatment boosted the prediction accuracy of the GA-PLSR model.The improvement achieved with the second derivative was more pronounced than when using the first derivative.The quantitative model developed in this work has the potential to estimate the contents of similar weathering basalt products,and thus infer the degree of alteration and provide insights into paleoclimatic conditions.Moreover,the informative bands selected by the GA can serve as a guideline for designing spectral channels for the next generation of spectrometers.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB 41000000).
文摘The InSight(Interior Exploration using Seismic Investigations,Geodesy,and Heat Transport)mission has recorded continuous ambient noise signals with many spectral peaks since its landing in 2018.The majority of these peaks are modes produced by instrumental vibrations and are associated with environmental factors,such as temperature and wind energy fluctuations.Understanding how these modes react under various conditions is crucial because it aids in identifying their origins.In this study,we analyzed the three-component spectra of InSight recordings from sols 184–738 and obtained the horizontal-to-vertical spectral ratio(HVSR,also known as H/V)curves for different time intervals.The primary modes,such as those at 3.3 and 4.1 Hz,exhibited different behaviors,suggesting diverse origins.Some modes were sensitive to low temperature and some were sensitive to high temperature.Additionally,we investigated the influence of wind and temperature on the H/V curve.The peak frequency was mainly affected by temperature,whereas the H/V value was not associated with the temperature or wind only.Characterizing these modes and elucidating their origins are significant for processing signals from InSight and can provide valuable guidance for designing future planetary seismometers.
文摘For planetary surface materials,thermal inertia is the critical property that governs the surface’s daily thermal response and controls diurnal and seasonal surface temperature variations.Here we use the ground measurements made by the MSL Curiosity rover and the InSight lander to determine the thermal inertia of two sites on Mars.This study compares the variation of thermal inertia during and after the Large Dust Storm(LDS)of Martian Year(MY)34.To determine surface thermal inertia,we derive a simple approximation(using energy balance),which utilizes surface albedo,surface energy flux,and diurnal change in the surface temperature.The average thermal inertia in MY34 is about 39.2%,3.7%,and 3.4%higher than MY35 average thermal inertia for the MSL,InSight(FOV1),and InSight(FOV2),respectively.Notably,the thermal inertia at the InSight(FOV1)is consistently lower by about 20 J·m^(-2)·s^(-1/2)·K^(-1) than the InSight(FOV2)site for all scenarios,indicating variation in the region’s surface composition.The best-fit surface albedo in MY34(determined using the KRC model)are about 0.08,0.05,and 0.03 higher than MY35 surface albedo for the MSL,InSight(FOV1),and InSight(FOV2),respectively.An increase in both surface albedo and thermal inertia during the LDS indicates that the underlying surface is both more thermally resistant and more reflective than the overlying loose dust.
文摘This review article aims to gather differences and similarities between planet Mars and planet Earth to determine the necessities for the proper growth and development of the neonatal brain. Factors such as Environmental, Nutritional, Social, Stress, and Education are juxtaposed to understand the difference between pediatric neurodevelopment on both planets. The variation between each factor was analyzed to determine how significant the impact is on neurodevelopment for children. The factors to be discussed were generated based on extensive research on what is most important for proper early neurodevelopment. The five factors are the main categories branched out into subcategories to delve into more detail regarding neurodevelopment. Factors may vary based on the location on each planet, but the best average was cultivated to create a fair evaluation of the differences. Although each factor influences a different part of the brain, each factor (Environmental, Nutritional, Social, Stress, and Education) is equally vital for development anatomy and physiology of the brain.
