The origin of the lunar surface

A mechanism is described how the lunar landscape could have originated by a chain reaction of volcanic eruptions. The mechanism consists of a sequence of three steps; surface solidification and fragmentation, gas formation and crack-wave interactions. A quantitative analysis is presented and it is shown that the volcanic chain reaction was most likely to occur around 10 million years after surface solidification.     

月球表面主要矿物反射光谱特性研究

分析了矿物在可见光及近红外区光谱生成的机理,介绍了月球表面最为主要的四种矿物——辉石、斜长石、橄榄石、钛铁矿,并分析了它们各自光谱特征及生成原因,讨论了造成同种矿物光谱差异的原因,给出了它们各自的标志性特征。     

The depth distribution of hydrogen in lunar materials

A technique employing the resonant nuclear reaction ¹H(¹⁹F, αγ) ¹⁶O has been used to measure hydrogen concentration versus depth in selected coarse fine fragments from the Apollo 11 and Apollo 15 missions, and in glass coated surface chips from two Apollo 15 rocks. The highly variable hydrogen content in the coarse fine fragments is concentrated mainly in a layer extending from the surface to a depth of 2000 ± 500A?. The hydrogen content of the surface region of the Apollo 15 rock chips is comparable to that of the coarse fine samples, but is concentrated mainly within a few hundred angstroms of the surface. The hydrogen depth distribution in a piece of platinum foil from the Apollo 16 Lunar surface Cosmic Ray Experiment was also measured in an attempt to place a limit on the flux of 10–40 keV protons associated with a solar flare event.     

月表温度对于月幔对流影响的数值模拟研究

行星内部对流计算中, 一般都将其表面温度作为常温处理.但在月球、水星等无大气的天体表面, 温度与纬度明显相关, 月球两极和赤道的平均温度相差可以达到100 K以上.纬度相关的温度边界条件, 是否会影响天体早期对流特征与内部热状态, 过去没有得到重视和研究.本文使用有限元方法进行了二维球壳对流模型的热演化模拟, 以评估无大气行星上, 与纬度高度相关的表面温度对其内部对流和演化的影响.模拟计算结果表明, 表面温度会对月球对流形态产生较大影响, 两极因为相对更冷而易于形成下降流, 上升流更倾向于从赤道位置开始, 在早期演化中表现得尤为明显.受边界条件影响, 月球两极与赤道的岩石圈厚度差异可以达到400 km以上.今后在研究太阳系内月球、水星一类没有大气的天体演化、特别是早期演化时, 对于表面温度纬度相关分布的影响应该予以考虑.

     

Comments on the surface composition of lunar soil grains

Baron et al. [1] have recently published X-ray photoemission spectroscopy analyses of the surface composition of lunar regolith fines sample 10084 showing almost a factor of two higher Fe than we found. They suggest that this discrepancy is due either to the choice of element lines analyzed or to the data reduction procedure used. We document the fact that neither of these possible explanations is correct and provide further arguments in support of our value.     

浅谈多角度偏振遥感技术及其在探测月球资源中的应用

在反射、散射和透射电磁辐射的过程中,地表或大气中的目标地物将产生与它们自身性质相关的偏振特性.多角度偏振探测技术就是利用物质的这种偏振特性,对目标地物进行全方位、多角度的观测,是当前遥感识别目标地物的一种新手段,目前在我国还处于基础性试验研究阶段.本文从多角度偏振技术的物理机理出发,阐述了该种技术在当前“月球探测热”中的应用设想,表明在当前“重返月球”计划中多角度偏振探测技术应用的可行性.最后讨论了今后多角度偏振技术的应用与发展.     

A limit on the radiation erosion in lunar surface material

Evidence from Apollo 11 and Apollo 12 lunar samples indicates that particle radiation is not important for the production of grains in the lunar soil greater than 22 microns in size even though sufficiently prolonged irradiations by protons, heavy ions and electrons fracture minerals and glasses like those found on the lunar surface.     

The solar and lunar effect of earthquake duration and distribution

Phase folding algorithms are conventionally used in periodicity analyses using X-ray astronomy pulsar. These allow for accurate identification of the cycle and phase characteristics of the physical parameters of the periodic variation. Although periodic variations in earthquake activity have long been studied, this paper is the first to apply the phase folding algorithm to the analysis of shallow (<70 km) seismic data for the period 1973–2010. The goal is to study the phase distribution characteristics of earthquake frequencies and we see a connection between earthquake occurrence and solar and lunar cycles. First, the rotation of the Sun may play a significant role in impacting on the occurrence time of earthquakes with magnitudes of less than 6.0. This may be especially pertinent for earthquakes with magnitudes between 5.0 and 6.0, when the modulation ratio reaches 12 %. The Moon’s gravity, which is generally thought to have the greatest influence on the global environment, may actually play less of a role on earthquake timing than the rotation of the Sun. Second, when we consider the world to be divided into 72 local regions based on latitude and longitude, we can see that there are more than a dozen regions with significant non-uniform distributions of earthquake occurrence time. In these regions, the ratio of χ ² to the number of degrees of freedom far exceeds five. As a result, we posit that some factors associated with the Sun–Earth–Moon relationship may trigger earthquake activity under certain temporal and spatial conditions.     

The lunar barometric tide,its global distribution and annual variation

Summary The global distribution of the lunar barometric tideL ₂ is investigated by spherical harmonic analysis, based on 104 stations for the annual mean, and on 85 stations for the three seasons. The main wave ofL ₂ is the one with wave number 2, but for a detailed study of the irregularities of the global distribution ofL ₂, waves with other wave numbers have also to be considered. Even the main wave ofL ₂ is asymmetric to the equator with the two lunar-daily pressure maxima occurring earlier in the Southern than in the Northern Hemisphere. The amplitudes at the same distances from the equator are greater in the Southern than in the Northern Hemisphere. These hemispheric differences are most pronounced during the D season. As found in earlier investigations the phase consiant ofL ₂ is always greater during the J season than during the D season. But the amplitudes are greatest during the J season only north of 30^oS. Farther south the amplitude maximum occurs during the D season.sponsored by the National Science Foundation     

On deducing the magnetization of the lunar surface from orbital surveys

A combination of orbital photographic, selenochemical and magnetic surveys may elucidate the mechanism by which the lunar surface became magnetized and possibly yield an estimate of the intensity of the ancient magnetizing field and its time variation. The determination of the size and shape of the magnetized regions requires the measurement of the altitude dependence of field, especially at low altitudes (< 100 km) and with a high enough sampling rate to resolve the profile at the edges of magnetized bodies. The planned Lunar Polar Orbiter may well provide the necessary data.     

月表有效太阳辐照度实时模型

月表太阳辐射是深入研究月表温度分布的关键问题之一. 本文根据月表有效太阳辐照度与太阳常数、太阳辐射入射角以及日月距离之间的关系,建立月表有效太阳辐照度的实时模型. 该模型在1950～2050年的100年内的理论误差百分比小于0.28％, 相对前人提出的模型在精度上有了很大程度的提高,能较为真实地反映月表有效太阳辐照度随时间的变化规律. 计算结果表明2007年月表太阳辐照度的年变化范围在1321.5～1416.6 W·m-2之间,平均为1368.0 W·m-2. 通过对月表太阳辐射入射角计算结果的分析,证实了月球的两极可能存在极昼极夜.     

Constraints on the origins of lunar magnetism from electron reflection measurements of surface magnetic fields

Apollo 15 and 16 subsatellite measurements of lunar surface magnetic fields by the electron reflection method are summarized. Patches of strong surface fields ranging from less than $\text{1}\text{4}$° to tens of degrees in size are found distributed over the lunar surface, but in general no obvious correlation is observed between field anomalies and surface geology. In lunar mare regions a positive statistical correlation is found between the surface field strength and the geologic age of the surface as determined from crater erosion studies. However, there is a lack of correlation of surface field with impact craters in the mare, implying that mare do not have a strong large-scale uniform magnetization as might be expected from an ancient lunar dynamo. This lack of correlation also indicates that mare impact processes do not generate strong magnetization coherent over ～ 10 km scale size. In the lunar highlands fields of >100 nT are found in a region of order 10 km wide and >300 km long centered on and paralleling the long linear rille, Rima Sirsalis. These fields imply that the rille has a strong magnetization (>5 × 10^?6 gauss cm³ gm^?1 associated with it, either in the form of intrusive, magnetized rock or as a gap in a uniformly magnetic layer of rock. However, a survey of seven lunar farside magnetic anomalies observed by the Apollo 16 subsatellite suggests a correlation with inner ejecta material from large impact basins. The implications of these results for the origin of lunar magnetism are discussed.     

Depth profile of53Mn in the lunar surface

Measurements of cosmic-ray produced⁵³Mn are reported for a series of lunar surface samples down to a depth of 416 g/cm². These results clearly illustrate the decrease in activity with depth as the incident galactic cosmic rays are absorbed. Below 60 g/cm² the production rate decreases exponentially with a mean length, λ, of about 220 g/cm². These results indicate that, at the Apollo 15 site, the lunar regolith has been unmixed, on a meter scale, for the last 5 my. The neutron activation technique for⁵³Mn, which allowed samples smaller than 200 mg to be used for these measurements, is described.     

Calibration of the space-borne microwave humidity sounder based on real-time thermal emission from lunar surface

Calibration is a key issue for quantitative application of meteorological satellite data.The complex space environment may cause many uncertainties in data cali...     

Specific surface area as a maturity index of lunar fines

Mature surface fines have an equilibrium specific surface area of about 0.6 m²/g, the equivalent mean particle size being about 3 μm. The adsorption behavior of inert gases (reversible isotherms) indicates that the particles are also non-porous in the size range of pores 10–300Å. Apparently in mature soils there is a balance in the forces which cause fining, attrition, pore filling and growth of lunar dust grains. Immature, lightly irradiated soils usually have coarser grains which reduce in size as aging proceeds. The specific surface area, determined by nitrogen or krypton sorption at 77°K, is a valuable index of soil maturity.     

The crystallisation of lunar basalts

The crystallisation of olivine (O) and silica (S) normative varieties of Apollo 11 crystalline rocks has been followed at 1 atm. The sequence of phases precipitating is (S): spinel, olivine, ilmenite, clinopyroxene plus plagioclase; and (O): spinel, olivine, ilmenite plus plagioclase, clinopyroxene. The last 50% (O) to 75% (S) of the liquid crystallises as a pyroxene-plagioclase-ilmenite cotectic over a narrow temperature range, approximately 1095 to 1125° C, leaving a small silica-rich residue.     

基于绕月单卫星和双星测量的月球重力场恢复仿真分析

月球重力场是月球科学研究的重要部分,是进一步了解月球内部结构和构造的基础,也是我国探月计划“嫦娥工程”一个重要的科学研究内容.本文针对“嫦娥工程”,利用GSFC/NASA/USA的GEODYNII/SOLVE轨道分析软件,分析计算了利用单星跟踪数据恢复月球重力场的能力,同时模拟计算了双星跟踪数据在恢复月球重力场方面的能力,结合可能的工程环境我们对两种情况分别给出了30天、60天和90天的计算结果.计算表明双星相比于单星对月球重力场的中低阶位系数有比较显著的改善.     

Major-element vapor fractionation on the lunar surface: An unusual lithic fragment from the Luna 20 fines

A 250-μm fragment in the Luna 20 fines has a very fine-grained “igneous” texture and has the composition (wt.%): SiO₂, 41.1; TiO₂, 0.35; Al₂O₃, 27.2; Cr₂O₃, 0.14; FeO, 4.2; MnO, 0.06; MgO, 8.5; CaO, 17.8; Na₂O, 0.05; and K₂O < 0.02. It contains ～ 65% plagioclase An_99–100, ～ 15% olivine Fo₉₀, ～ 2% Mg-Al spinel and the remainder an unusual interstitial phase with composition SiO₂, 34.8; TiO₂, 1.78; Al₂O₃, 18.3; Cr₂O₃, 0.04; FeO, 14.1; MnO, 0.22; MgO, 5.0; CaO, 24.1; Na₂O, 0.34; K₂O < 0.02. This fragment probably represents a portion of a normal highland rock (anorthositic norite) which was heated to a very high temperature by impact, lost volatiles including SiO₂, and then partially crystallized. The observed phases and their inferred crystallization sequence are consistent with experimental results in the system CaOMgOAl₂O₃SiO₂ (Schairer and Yoder, 1969), assuming the unusual phase to be a residual glass. This type of internal fractionation, leading to silica depletion in the residuum, is different from that normally observed in lunar rocks and is attributed to slightly lower bulk SiO₂ resulting from vapor fractionation due to impact (which also results in lower Na₂O and other volatiles). Because differentiation of the type shown by this fragment is rare in lunar materials, we infer that such major-element vapor fractionation is uncommon on the surface of the moon. The experimental CaOMgOAl₂O₃SiO₂ phase relations also have a bearing on the lunar model proposed by D.L. Anderson in 1973: his “refractory” original lunar composition would differentiate to produce silica deficient liquids, like the unusual phase in our fragment, rather than the normal lunar crustal rocks.     

On the heat budget of the moon and the surface temperature variation during a lunar eclipse

Summary The analysis of surface temperature variations of the moon is based on the equations of heat conduction and heat continuity in the interior of the moon andStefan's law. During a well-defined process, as exemplified by a lunar eclipse, the local heat budget equation establishes a boundary condition at the moon surface which must be satisfied by solutions of the thermal diffusion equation in the interior. Three simplified models of the general case are discussed. They are characterized by special assumptions regarding the depth and time dependency of the thermic qualities of the material underlying the moon's surface. In short, the thermal diffusivity is assumed to be constant in the first model, a linear depth function in the second and a time function in the third. A unique solution can be obtained for model No. I such that the absolute surface temperature is approximately inversely proportional to the 6th root of time during the phase of total eclipse.Epstein's conclusion that the average surface of the moon might consist of highly porous rocks or fine dust is confirmed by the order of magnitude of the heat conductivity which produces the best fit between the theoretical curves and a plot ofPettit's observational data during the lunar eclipse of 1939. Existing differences between the observed and theoretical curves during the totality phase of the eclipse can be reduced by the employment of the second model. A crude estimate shows that the average dust cover resting on more solid ground of lunar rocks might possibly have a thickness of approximately 0.5 meters.