火星表面硫酸盐探测与研究进展

作为太阳系类地行星中与地球最为类似的一颗行星,火星是人类深空探测的重要目标,也是未来太空移民的主要候选星球。火星探测至今已有60多年的历史,到目前共有47次探测任务对火星开展探测并取得了一系列重要科学发现。硫酸盐作为火星表面水蚀变/水岩作用重要的产物,对其展开研究可以深入了解火星水演化历史和气候变化特征,助力评估地表环境宜居性和生命痕迹的可能性等重大科学问题。本文主要回顾了火星硫酸盐的轨道遥感与就位探测研究进展,探讨了硫酸盐模拟实验研究的科学意义以及硫酸盐对未来火星资源利用的重要价值,以期为未来火星探测任务和火星科研站建设提供有益参考。

火星无线电掩星探测进展

火星是地球的姊妹星,研究火星对了解火星、地球乃至太阳系的演化具有重要意义.自从1964年美国水手4号发射,首次成功地运用无线电掩星技术探知到火星的环境特征之后,国际上不少的火星任务都开展了掩星实验,取得了重要进展.本文依据采用了无线电掩星技术进行勘探的火星探测器发射时间顺序展开调研,针对具有开创性的水手系列、火星全球勘测者、火星快车、火星大气挥发演化探测器、天问一号等,梳理分析和总结了各任务的火星无线电掩星方式以及所获取的廓线数量、位置分布、获取方式等产品信息,以及部分相关的研究结果.本文还分析了当前火星无线电掩星探测方式存在的局限性,并探讨了可能的对策.火星无线电掩星后续可重点考虑多颗星-星掩星结合星-地掩星方式形成掩星星座;并通过选用适当的信号探测频率、改进反演算法等方式进一步提高掩星质量;火星掩星探测手段还可与火星顶部探测雷达、直接探测等手段相结合,发展火星多源数据融合技术.随着探测方式的不断改进,无线电掩星探测将是火星探测的重要手段.未来会有数量越来越多、时间与空间覆盖越来越全面、精度越来越高的掩星数据用于火星的整个空间环境研究,包括大、中尺度乃至小尺度结构的特征与演化规律都将被人类掌握.

火星资源赋存状况及其原位利用技术研究进展与展望

太空资源的勘探及利用是深空探测的重要目的之一。火星是人类最容易到达和资源利用最为迫切的行星,对火星资源进行勘查和原位利用是未来火星载人探测及基地建设需要解决的重要问题。本文对火星大气资源、水资源、土壤与岩石矿物资源、风能与太阳能资源等可利用资源的类型及赋存状况进行了分析,制作了火星资源的全球分布图,并从资源分布的角度提出了未来火星资源探测及火星基地建设的首选区域。同时,本文也总结了火星原位资源利用技术的研究进展及问题,认为未来需要从以下几个方面开展进一步研究:加强火星资源的针对性勘查与评估;开发新的资源利用模式与技术;建立资源利用成本的综合评估模型;完善资源开发与利用相关的法律法规。

火星弓激波上游离子回旋波的观测研究

离子回旋波广泛分布于火星弓激波上游,在卫星坐标系下其频率接近当地质子回旋频率,准平行于背景磁场方向传播,与在火星外逸层太阳风拾起新生H离子有关。该文基于磁流体理论,对MAVEN探测器观测到的离子回旋波进行事例分析,通过对等离子体密度扰动、速度扰动以及磁场扰动的参数拟合,发现该离子回旋波事件可用斜传播的快磁声波与平行传播的阿尔文波的叠加来解释。该文有助于进一步理解火星上游所观测到的离子回旋波相关扰动的物理本质,对其中等离子体物理过程的重新建模和数值模拟具有指导意义。

火星陨石NWA 13763矿物岩石学特征及其岩浆演化

NWA 13763陨石为一块新发现的辉长质辉玻无球粒火星陨石,辉长结构和次辉绿结构,主要矿物组成为辉石(45.1%,其中普通辉石36.1%,易变辉石9.0%)和斜长石(42.3%,几乎全部熔长石化),次要矿物组成为富硅相(5.1%)、橄榄石(2.7%)、磷酸盐矿物(2.4%)、钛铁矿(2.2%),含极少量钛磁铁矿和斜锆石。陨石中广泛发育“铁橄榄石+富硅相”二相后成合晶和“钙铁辉石+铁橄榄石+富硅相”三相后成合晶。辉石主晶核部贫铁富镁(Fs_(24.7-55.3)),边部富铁贫镁(Fs_(61.5-86.1));熔长石成分均一(An_(44.4-54.6Ab43.7-53.7));铁橄榄石(Fa_(84.5-97.7))全部以细粒状分布于后成合晶中。由钛铁氧化物固溶体计算得到岩浆结晶的氧逸度(FMQ)f_(O_(2))=-0.045,钛铁矿结晶温度约975℃。利用全岩成分和MELTS程序模拟计算表明,NWA 13763陨石的母岩浆液相线温度范围可能为1190~830℃,矿物结晶顺序由早到晚可能为:培长石→拉长石→橄榄石→单斜辉石→中长石→磷酸盐矿物→钛铁矿→富硅残余相。

火星早期分异形成的不均一地幔和地壳结构

火星陨石主要为玄武质,年龄通常介于>44亿年和<0.2亿年之间。对火星陨石的研究显示,火星比地球更早完成吸积和核形成,它曾经是完全熔融的,经历早期撞击作用引起的地壳氧化,以及液态水和表面蚀变等过程。在缺少来自火星样品的情况下,火星陨石对于理解不同类型的岩石成因,构建地球化学和地球物理模型至关重要。

交代作用是火星上甲烷的来源之一

解释火星早期气候更温暖的关键之一是火星大气中存在的还原性温室气体(如甲烷和氢气)。甲烷在地球与火星大气中的形成机制,及其对其它类地行星或系外行星气候的潜在长期影响尚未明确,需要深入研究。为了研究火星壳-幔边界岩浆流体的碳化学种型的生成规律,美国圣安德鲁斯大学地球与环境学院和约翰斯霍普金大学地球与行星科学系的研究人员合作,使用了一种热力学模型—深地球水模型(Deep Earth Water model)来预测流体-岩石交代变质过程中的碳元素分配。这项研究实验条件的温度范围是300~800℃,压强为0.5 GPa,并同时结合了不同的氧逸度情况进行了模拟。

Snow and regolith albedo variations using CRISM data at McMurdo crater,Mars

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).

Evaluating the biosignature potential of ammonium in Proterozoic red beds and implications for the search for life on Mars

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.

Research on internal gravity waves in the Martian atmosphere based on Tianwen-1 and Mars Global Surveyor occultation data

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.

Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere

Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity(∣BIMF∣),solar wind dynamic pressure(PS W),solar extreme ultraviolet flux(EUV),and Martian seasons(L s).Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and PS W.Correlations observed with EUV flux and Ls were weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars perihelion.We find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣andPSWconditions.Our analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration depth.Those findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed now.Moreover,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field.

Quantifying the chemical composition of weathering products of Hainan basalts with reflectance spectroscopy and its implications for Mars

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.

Response of InSight resonance modes to environmental factors on Mars

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.

The anisotropy of suprathermal electrons in the Martian ionosphere

Suprathermal electrons are an important population of the Martian ionosphere, either produced by photoionization of atmospheric neutrals or supplied from the Solar Wind (SW). This study is dedicated to an in-depth investigation of the pitch angle distribution of suprathermal electrons at two representative energies, 19−55 eV and 124−356 eV, using the extensive measurements made by the Solar Wind Electron Analyzer on board the Mars Atmosphere and Volatile Evolution. Throughout the study, we focus on the overall degree of anisotropy, defined as the standard deviation of suprathermal electron intensity among different directions which is normalized by the mean omni-directional intensity. The available data reveal the following characteristics: (1) In general, low energy electrons are more isotropic than high energy electrons, and dayside electrons are more isotropic than nightside electrons;(2) On the dayside, the anisotropy increases with increasing altitude at low energies but remains roughly constant at high energies, whereas on the nightside, the anisotropy decreases with increasing altitude at all energies;(3) Electrons tend to be more isotropic in strongly magnetized regions than in weakly magnetized regions, especially on the nightside. These observations indicate that the anisotropy is a useful diagnostic of suprathermal electron transport, for which the conversion between the parallel and perpendicular momenta as required by the conservation of the first adiabatic invariant, along with the atmospheric absorption at low altitudes, are two crucial factors modulating the observed variation of the anisotropy. Our analysis also highlights the different roles on the observed anisotropy exerted by suprathermal electrons of different origins.

MAVEN observation of magnetosonic waves in the Martian magnetotail region

Magnetosonic waves are an important medium for energy transfer in collisionless space plasma.Magnetosonic waves have been widely investigated in the upstream of the bow shock at Mars.These waves are believed to originate from pickup ions or reflected particles.By utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail region.These plasma waves are associated with a significant enhancement of proton and oxygen flux.The excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma escape.Our results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere.

SCIENCE AND TECHNOLOGY

China's Queqiao-2 Relay Satellite Enters Lunar Orbit China's Queqiao-2 relay satellite has successfully performed a near-moon braking procedure and entered its circumlunar orbit,according to the China National Space Administration(CNSA).At 12.46 a.m.(Beijing Time)on March 25,after approximately 112 flight hours,the satellite began near-moon braking at a distance of approximately 440 kilometers from the lunar surface and entered its circumlunar orbit 19 minutes later,the CNSA said.

SuperCam-LIBS光谱定量分析火星锰元素

毅力号火星车携带的SuperCam载荷可以探测火星表面锰元素等成分信息。本研究依据SuperCam团队发布的地质标样激光诱导击穿光谱(LIBS)数据集,提出了一种基于集成学习的火星锰元素定量方法。本研究首先对LIBS光谱进行光谱降噪、去基线等预处理,随后进行光谱反卷积和分峰拟合,最终建立锰元素的定量方法,实现了锰元素的含量预测。实验评估了传统多变量定量方法(LASSO、弹性网络)和集成学习方法对锰元素定量精度的差异,发现后者的均方根误差相对于前两种传统方法分别平均下降了49%和30%,定量结果更接近样品真实值,表明基于集成学习的定量方法更适用于火星锰元素的定量反演。

应用重力场模型二阶位系数及新近岁差率约束火星内核大小及密度组成

针对当前InSight数据无法检测火星固态内核是否存在的问题,提出利用火星平均密度和平均惯性矩因子估算火星固态内核的大小及其密度组成.根据火星高阶重力场模型JGMRO120f和GMM3-120以及最新火星岁差率,推导了观测数据下的火星平均密度和平均惯性矩因子;参考火星内部结构的4层模型以及不同自由参数(壳层密度、幔层密度、外核密度、内核大小和内核密度),求解了火星平均密度和平均惯性矩因子的模型值.利用观测值与模型值最小残差平方和作为约束条件,大批量统计结果表明:1)两个重力场模型求解的自由参数具有相同的分布特征,自由参数的最优值基本一致;2)火星壳层密度、幔层密度和外核密度接近其他研究结果,表明统计结果有一定的参考价值;3)火星可能存在840 km左右的固态内核,其密度约为6950 kg·m^(-3).内核密度大小表明火星内核不由纯铁物质组成,该结果与火星核富集轻元素物质的近期研究一致,计算结果具有一定的参考价值.由于反演结果的非唯一性,未来随着InSight火星星震数据处理技术的提高,有望进一步约束火星内核的大小及其组成.

火星样品记录火星表面水体演变

探测火星的终极目标是探索火星生命。水是影响生命起源和演化、地质活动、表生环境等重大科学问题的重要因素,不仅是火星探测的主旋律,更是火星科学研究关注的重要内容。火星与地球是位于太阳系宜居带的两颗非常相似的行星,普遍认为火星早期存在过液态水,推测火星早期与当今地球具有相似的宜居环境,具备孕育生命的必要条件;但是,现在的火星已经转变成干燥寒冷的星球,火星沧海变干漠的原因和演化过程是火星研究的重大科学问题。为了揭示火星表面水体的演化过程和细节,开展了持续不断的火星探测任务,以及火星陨石样品的水含量与氢同位素组成研究,为揭示火星表面水体的消失过程提供了多视角和多维度的证据。本文主要从火星样品的视角,梳理过去近十几年来,国内外在火星表面水体演化研究中的主要进展、存在问题和重要启示,凝练火星表面水体演化的关键科学问题与突破方向,为我国未来火星探测提供参考。

火星取样返回的必要性与科学目标

1引言相信大家不会对火星取样返回(MSR)这个词感到陌生。除了中国已正式宣布火星取样返回探测计划之外,美国国家航空航天局(NASA)和欧洲航天局(ESA)也宣布了火星取样返回探测计划,并公布了该计划的执行细节。尽管国内外有了火星取样返回计划,但毕竟还都没有实现,国内对这方面的报道也比较少。本文就人们普遍关心的问题进行介绍,主要涉及一些基本问题,如:为什么要取样返回?取样返回的科学目标是什么?到火星的什么地方选取样品等。