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1.
M. Nafi Toksőz Sean C. Solomon John W. Minear David H. Johnston 《Earth, Moon, and Planets》1972,4(1-2):190-213
The thermal history and current state of the lunar interior are investigated using constraints imposed by recent geological and physical data. Theoretical temperature models are computed taking into account different initial conditions, heat sources, differentiation and simulated convection. To account for the early formation of the lunar highlands, the time duration of magmatism and presentday temperatures estimated from lunar electrical conductivity profiles, it is necessary to restrict initial temperatures and abundances of radioactivie elements. Successful models require that the outer half of the Moon initially heated to melting temperatures, probably due to rapid accretion. Differentiation of radioactive heat sources toward the lunar surface occurred during the first 1.6 billion years. Temperatures in the outer 500 km are currently low, while the deep interior (radius less than 700 to 1000 km) is warmer than 1000°C, and is of primordial material. In some models there is a partially melted core. The calculated surface heat flux is between 25 and 30 erg/cm2 s.Presently at the Research Triangle Institute, Research Triangle, North Carolina 27709, U.S.A. 相似文献
2.
Possible models for the thermal evolution of the Moon are constrained by a wide assortment of lunar data. In this work, theoretical lunar temperature models are computed taking into account different initial conditions to represent possible accretion models and various abundances of heat sources to correspond to different compositions. Differentiation and convection are simulated in the numerical computational scheme.Models of the thermal evolution of the Moon that fit the chronology of igneous activity on the lunar surface, the stress history of the lunar lithosphere implied by the presence of mascons, and the surface concentrations of radioactive elements, involve extensive differentiation early in lunar history. This differentiation may be the result of rapid accretion and large-scale melting or of primary chemical layering during accretion. Differences in present-day temperatures for these two possibilities are significant only in the inner 1000 km of the Moon and are not resolvable with presently available data.If the Apollo 15 heat flow is a representative value, the average uranium concentration in the moon is 65±15 ppb. This is consistent with achondritic bulk composition (between howardites and eucrites) for the Moon.Paper dedicated to Professor Harold C. Urey on the occasion of his 80th birthday on 29 April 1973. 相似文献
3.
The thermal evolution of the Moon as it can be defined by the available data and theoretical calculations is discussed. A wide assortment of geological, geochemical and geophysical data constrain both the present-day temperatures and the thermal history of the lunar interior. On the basis of these data, the Moon is characterized as a differentiated body with a crust, a 1000-km-thick solid mantle (lithosphere) and an interior region (core) which may be partially molten. The presence of a crust indicates extensive melting and differentiation early in the lunar history. The ages of lunar samples define the chronology of igneous activity on the lunar surface. This covers a time span of about 1.5 billion yr, from the origin to about 3.16 billion yr ago. Most theoretical models require extensive melting early in the lunar history, and the outward differentiation of radioactive heat sources.Thermal history calculations, whether based on conductive or convective computation codes define relatively narrow bounds for the present day temperatures in the lunar mantle. In the inner region of the 700 km radius, the temperature limits are wider and are between about 100 and 1600°C at the center of the Moon. This central region could have a partially or totally molten core.The lunar heat flow values (about 30 ergs/cm2s) restrict the present day average uranium abundance to 60 ± 15 ppb (averaged for the whole Moon) with typical ratios of K/U = 2000 and Th/U = 3.5. This is consistent with an achondritic bulk composition for the Moon.The Moon, because of its smaller size, evolved rapidly as compared to the Earth and Mars. The lunar interior is cooling everywhere at the present and the Moon is tectonically inactive while Mars could be and the Earth is definitely active. 相似文献
4.
5.
D. C. Tozer 《Earth, Moon, and Planets》1972,5(1-2):90-105
Heat convection, being a more general theory than conduction theory, compels one to give reasons for using the latter theory as the basis of thermal evolution studies. Such reasons are supplied by considerations of material rheology.The specific case of the thermal regime of the Moon is first considered as a steady state problem. It is demonstrated that no plausible creep resistance of lunar material and heat generation is compatible with a purely conductive theory of lunar thermal evolution. The most plausible, steady state models give convective cores extending to within 200–300 km of the surface. The radial temperature gradients in such cores is virtually confined to a thermal boundary layer but averages to about a tenth of degree/km. The (steady) central temperature for the most plausible lunar rheologies lie between 600–1000°C. Such models are compatible with the first interpretations of lunar magnetometry. The case for considering the lunar thermal state as such a quasi-static state is discussed.It is also predicted that in very local zones the viscous dissipation of the general circulation produces much higher temperatures. Chemical differentiation and seismicity would have their origin in such low viscosity zones. 相似文献
6.
J. A. Bastin 《Earth, Moon, and Planets》1974,10(2):143-162
A new liquefaction theory for the origin of the flat marial and Cayley areas on the lunar surface is described. It is supposed that the flat terrain in these areas resulted from periods in the development of the Moon when these regions, although not liquid, had a sufficiently low viscosity for the surfaces to relax more or less completely to a level form. To account for this low viscosity a model is developed in which, within these regions and for relatively short periods in the early history of the Moon, preferentially high temperatures were maintained close to the lunar surface. The paper examines in some detail the possibility that these high temperatures may have resulted from instabilities in the lunar heat flow pattern caused by the presence of a surface layer of very low thermal conductivity produced by the debris of early meteorite impacts.A comparison is made between current models for the formation of the lunar surface and the theory here proposed: the advantages of the latter are enumerated and discussed.Normally at Queen Mary College, University of London, England. 相似文献
7.
Magma genesis in the Moon could have been significantly altered by large impacts if they melted solidified residual liquids and late cumulates from the ‘magma ocean’. Calculations of the heat required to melt these materials, under different assumed conditions, are compared to estimates of the total kinetic energy of the Imbrium impact. For a significant amount of these materials to have been melted, they must have been near their solidus temperatures, the impacts must have been very large, and the lunar lithosphere must have been locally heated at depths of 70 to 140 km. Unless the Imbrium impact released at least the maximum estimated kinetic energy, only larger impacts, e.g., the proposed ‘Gargantuan’ impact, could have augmented the intrinsic lunar heat budget enough to locally alter the abundance, timing of eruption, and chemical compositions of lunar magmas. The mechanical and thermal energy generated by such an impact could have been critical in creating (1) the higher concentrations of radioactive elements in the Imbrium/Procellarum area by migration of residual liquids driven by differential lithospheric thickness; and (2) hybrid mare basalts (representing varying proportions of late cumulates and/or residual liquids incorporated into primitive magmas rising from the partially molten lunar interior). Complete compositional spectra of lunar basalts are to be expected, from primitive mare basalts to pure KREEP and to Ti-rich varieties. Comparison of the Gargantuan/Imbrium area with ancient basins in the eastern nearside area suggests that the interplay between the Moon's internal heat engine and the timing of large impacts was a crucial factor in determining the time of tunar volcanism and the chemical composition of the lavas. 相似文献
8.
According to the incidence and azimuth angles of the Sun during observations of Chinese Chang’E-1 (CE-1) lunar satellite, brightness temperatures (Tb) at different lunar local time observed by the CE-1 multi-channel radiometers, especially at the Sinus Iridum (i.e. Bay of Rainbow) area, are collected from the transformation between the principal and local coordinates at the observed site, which demonstrates the Tb distribution and its diurnal variation. Based on a three-layer radiative transfer model of the lunar media, the CE-1 Tb data at 19.35 and 37.0 GHz channels are applied to invert the physical temperatures of both the dust and the regolith layer at Sinus Iridum area, where might be the CE-3 landing site, at different lunar local times. The physical temperature variations with the lunar local time and other geophysical parameters of lunar layered media are discussed. 相似文献
9.
Numerous investigations of the electrical conductivity of lunar and terrestrial materials as a function of temperature have been performed to date in an attempt to provide data on which to base lunar interior temperatures from magnetometer-derived lunar conductivity profiles (Schwereret al., 1971, 1972, 1973; Dubaet al., 1972 and others). There are several pitfalls inherent in the extrapolation of lunar temperatures from laboratory measurements of electrical conductivity. These include the choice of representative material for the lunar interior, appropriate environmental conditions (pressure, fugacity, etc.) and the various measurement difficulties.Presented at the Geophysical and Geochemical Exploration of the Moon and Planets Conference, January, 1973, Lunar Science Institute, Houston, Tex., U.S.A. 相似文献
10.
Comparisons of calculated diurnal and eclipse temperatures of the lunar outermost layer are made with Earth-based infrared and millimeter data. The thermophysical model upon which the calculations are based incorporates variable physical properties. The thermal conductivity is a function of both density (depth) and temperature; the specific heat is a function of temperature; the density is a function of depth; and the dielectric constant and loss tangent are functions of density (depth). Laboratory measurements and Apollo sample results are incorporated in the property data. Calculational cases are based largely upon different density profiles. The model is consistent with the data, and the comparisons of theoretical and observational temperatures are very favorable. For such comparisons, further sophistication of the thermophysical model of the outermost layer is probably not justified. 相似文献
11.
Walter S. Kiefer 《Planetary and Space Science》2012,60(1):155-165
Reliable measurements of the Moon's global heat flow would serve as an important diagnostic test for models of lunar thermal evolution and would also help to constrain the Moon's bulk abundance of radioactive elements and its differentiation history. The two existing measurements of lunar heat flow are unlikely to be representative of the global heat flow. For these reasons, obtaining additional heat flow measurements has been recognized as a high priority lunar science objective. In making such measurements, it is essential that the design and deployment of the heat flow probe and of the parent spacecraft do not inadvertently modify the near-surface thermal structure of the lunar regolith and thus perturb the measured heat flow. One type of spacecraft-related perturbation is the shadow cast by the spacecraft and by thermal blankets on some instruments. The thermal effects of these shadows propagate by conduction both downward and outward from the spacecraft into the lunar regolith. Shadows cast by the spacecraft superstructure move over the surface with time and only perturb the regolith temperature in the upper 0.8 m. Permanent shadows, such as from thermal blankets covering a seismometer or other instruments, can modify the temperature to greater depth. Finite element simulations using measured values of the thermal diffusivity of lunar regolith show that the limiting factor for temperature perturbations is the need to measure the annual thermal wave for 2 or more years to measure the thermal diffusivity. The error induced by permanent spacecraft thermal shadows can be kept below 8% of the annual wave amplitude at 1 m depth if the heat flow probe is deployed at least 2.5 m away from any permanent spacecraft shadow. Deploying the heat flow probe 2 m from permanent shadows permits measuring the annual thermal wave for only one year and should be considered the science floor for a heat flow experiment on the Moon. One way to meet this separation requirement would be to deploy the heat flow and seismology experiments on opposite sides of the spacecraft. This result should be incorporated in the design of future lunar geophysics spacecraft experiments. Differences in the thermal environments of the Moon and Mars result in less restrictive separation requirements for heat flow experiments on Mars. 相似文献
12.
Remote observations of the lunar radiowave emission are reexamined in the light of physical property data accumulated through the Apollo program. It is found that thermal and electrical properties determined for a number of different landing sites yield theoretical results in good agreement with remote observations for millimeter and short centimeter wavelengths. Theoretical models incorporating reflecting layers of rock and physical property data from the Apollo program are compared to the longer wavelength (5–500 cm) observational data to estimate a disk average steady state heat flow and a mean depth of the lunar regolith. It is found that a high heat flow, comparable to the heat flows measured at the Apollo 15 and 17 sites, is required to fit the available 5–20 cm wavelength remote data, and that a lunar surface layer relatively free of large boulders within the upper 10–30 m best fits the observations of a decreasing brightness temperature with wavelength for wavelengths greater than ～ 50 cm. 相似文献
13.
An empirically derived lunar gravity field 总被引：1，自引：0，他引：1
A. J. Ferrari 《Earth, Moon, and Planets》1972,4(3-4):390-410
The heat-flow experiment is one of the Apollo Lunar Surface Experiment Package (ALSEP) instruments that was emplaced on the lunar surface on Apollo 15. This experiment is designed to make temperature and thermal property measurements in the lunar subsurface so as to determine the rate of heat loss from the lunar interior through the surface. About 45 days (1 1/2 lunations) of data has been analyzed in a preliminary way. This analysis indicates that the vertical heat flow through the regolith at one probe site is 3.3 × 10–6 W/cm2 (±15%). This value is approximately one-half the Earth's average heat flow. Further analysis of data over several lunations is required to demonstrate that this value is representative of the heat flow at the Hadley Rille site. The mean subsurface temperature at a depth of 1 m is approximately 252.4K at one probe site and 250.7K at the other. These temperatures are approximately 35K above the mean surface temperature and indicate that conductivity in the surficial layer of the Moon is highly temperature dependent. Between 1 and 1.5m, the rate of temperature increase as a function of depth is 1.75K/m (±2%) at the probe 1 site. In situ measurements indicate that the thermal conductivity of the regolith increases with depth. Thermal-conductivity values between 1.4 × 10–4 and 2.5 × 10–4 W/cm K were determined; these values are a factor of 7 to 10 greater than the values of the surface conductivity. If the observed heat flow at Hadley Base is representative of the moonwide rate of heat loss (an assumption which is not fully justified at this time), it would imply that overall radioactive heat production in the Moon is greater than in classes of meteorites that have formed the basis of Earth and Moon bulk composition models in the past.Lamont-Doherty Geological Observatory Contribution Number 1800. 相似文献
14.
Franklin Hadley Cocks 《Icarus》2010,206(2):778-779
Because of their cryogenic temperatures, analysis indicates that permanently shadowed polar lunar craters may have substantially higher levels of 3He than sunlit lunar surfaces and are conservatively estimated to contain as much as 50 ppb or more. 相似文献
15.
Data on thermophysical properties measured on lunar material returned by Apollo missions are reviewed. In particular, the effects of temperature and interstitial gaseous pressure on thermal conductivity and diffusivity have been studied. For crystalline rocks, breccias and fines, the thermal conductivity and diffusivity decrease as the interstitial gaseous pressure decreases from 1 atm to 10–4T. Below 10–4T, these properties become insensitive to the pressure. At a pressure of 10–4T or below, the thermal conductivity of fines is more temperature dependent than that of crystalline rocks and breccias. The bulk density also affects the thermal conductivity of the fines. An empirical relationship between thermal conductivity, bulk density and temperature derived from the study of terrestrial material is shown to be consistent with the data on lunar samples. Measurement of specific heat shows that, regardless of the differences in mineral composition, crystalline rocks and fines have almost identical specific heat in the temperature range between 100 and 340K. The thermal parameter calculated from thermal conductivity, density and specific heat shows that the thermal properties estimated by earth-based observations are those characteristic only of lunar fines and not of crystalline rocks and breccias. The rate of radioactive heat generation calculated from the content of K, Th and U in lunar samples indicates that the surface layer of the lunar highland is more heat-producing than the lunar maria. This may suggest fundamental differences between the two regions.Now at Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York, U.S.A. 相似文献
16.
Edgar L Andreas 《Icarus》2007,186(1):24-30
The strong hydrogen signal that the Lunar Prospector saw at the Moon's poles suggests that water ice may be present near the surface of the lunar regolith. A robotic mission to obtain in situ samples and to quantify the amount of this valuable resource must be designed carefully to avoid dissipating too much heat in the regolith during coring or drilling and, thus, causing the ice to sublimate before it is processed. Here I use new results for the saturation vapor pressure of water ice to extend previous estimates of its sublimation rate down to a temperature of 40 K, typical of the permanently shaded craters near the lunar poles where the water ice is presumed to be trapped. I find that, for temperatures below 70 K, the sublimation rate of an exposed ice surface is much less than one molecule of water vapor lost per square centimeter of surface per hour. But even if a small ice sample (∼4 ng) were heated to 150 K, it could exist for over two hours without sublimating a significant fraction of its mass. Hence, carefully designed sampling and sample handling should be able to preserve water ice obtained near the lunar poles for an accurate measurement of its in situ concentration. 相似文献
17.
John A. Wood 《Icarus》1972
Lunar heat-flow calculations are carried out for a model Moon in which (a) near-surface initial temperatures are very high (as the occurence of a surface anorthositic layer seems to require), and (b) heat-generating radionuclides are transported upward when melting occurs. Near-surface regions are found to cool and then experience a resurgence of high temperature, as radionuclide-rich magmas from the lunar interior accumulate near the surface. This peaking of near-surface temperature can be brought into correspondence with the episode of vulcanism (∼ 3.5 × 109 years ago) that gave rise to the basalts represented in the Apollo samples, if we assume relatively high lunar temperatures in early times (due to high initial temperatures, or high content of radioactive elements, or both). 相似文献
18.
Jeffrey L. Linsky 《Solar physics》1973,28(2):409-418
The solar millimeter continuum between 1 and 20 mm is recalibrated using observations of the average lunar brightness temperature at the center of lunar disk and new Moon brightness temperatures. The solar data are placed on a common scale according to the average lunar brightness temperature distribution proposed by Linsky. A least-squares parabolic regression curve is proposed for the solar millimeter continuum. A small departure from this regression curve near 8 mm may indicate the existence of an absorption feature.Staff member, Laboratory Astrophysics Division, National Bureau of Standards. 相似文献
19.
The thermal emission of the lunar surface has been mapped by an infrared scanner from lunar orbit. Samples from approximately 2.5 × 105 scans reveal the full range of lunar temperatures from 80 K to 400 K. The temperature resolution was 1 K with about ± 2 K absolute precision. Spatial resolution was approximately 2 km over most of the horizon-to-horizon scan. The total mapped area amounted to approximately 30% of the lunar surface. The data currently available confirms the large population of nighttime thermal anomalies in western Oceanus Procellarum predicted by Earthbased observations. Most of these ‘hot spots’ are associated with fresh impact features or boulder fields. Also seen in the data are ‘cold spots’ where 相似文献
20.
One hundred metallic particles from Apollo 16 soils (61181, 65701) and rocks (60018, 60315, 66055) have been investigated microscopically and by electron microprobe analysis. Their cobalt content indicates a meteoritic origin for all but one particle. However, most contain more phosphorus than typical meteoritic metal, possibly due to the reduction of phosphates in the lunar rocks. Compositions of coexisting kamacite and schreibersite indicate temperatures of about 550–650°C which are thought to have occurred during metamorphism. The bulk nickel content of the lunar metal is somewhat low by comparison with most iron meteorites or the metallic component of common stony meteorites. However, this may be due to compositional changes that occurred after emplacement in the lunar surface layer. 相似文献