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1.
Wänke H Begemann F Vilcsek E Rieder R Teschke F Born W Quijano-Rico M Voshage H Wlotzka F 《Science (New York, N.Y.)》1970,167(3918):523-525
Analytical data for 42 major and trace elements were mostly obtained by a combination of instrumental and radiochemical neutron activation analyses using both thermal and 14-million-electronvolt neutrons. Excesses of nitrogen and chlorine in the fines, compared with the rocks, are attributed to the solar wind. A striking similarity for contents of seven elements in lunar metal and metal from the calcium-rich achondrite Juvinas was noted. Fractional dissolution was used to separate five radionuclides produced by cosmic-ray bombardment in the fines and rock 57-40. Results for argon-39 from the reaction potassium-39 (n,p), and for argon-37, from the reaction calcium-40 (n,a), seem to require a neutron spectrum conitaining more neutrons below 2 million electronvolts than the evaporation spectrum or that given by Arnold, Honda, and Lal (1) or a strong time dependence for the neutron flux. 相似文献
2.
Atomic sodium is a useful tracer of the tenuous lunar atmosphere because of its high efficiency in scattering sunlight at the D(1) (5896 angstroms) and D(2) (5890 angstroms) wavelengths. In 1988, Earth-based instruments revealed the presence of sodium at a density of less than 50 atoms per cubic centimeter at lunar altitudes below 100 kilometers. Telescopic observations that are made with a coronograph technique to block out the disk of the moon allow a true picture of the circumiunar atmosphere to be obtained and show the presence of sodium out to a distance of several lunar radii. The distribution of sodium has a solar zenith angle dependence, suggesting that most of the sodium that reaches great altitudes is liberated from the moon's surface by solar photons (by heating or sputtering) or by solar wind impact, in contrast to a source driven by uniform micrometeor bombardment. 相似文献
3.
Fastie WG Feldman PD Henry RC Moos HW Barth CA Thomas GE Donahue TM 《Science (New York, N.Y.)》1973,182(4113):710-711
An ultraviolet spectrometer aboard the Apollo 17 orbiting spacecraft attempted to measure ultraviolet emissions from the lunar atmosphere. The only emissions observed were from a transient atmosphere introduced by the lunar landing engine. The absence of atomic hydrogen implies that solar wind protons are converted to hydrogen molecules at the lunar surface. 相似文献
4.
Discovery of vapor deposits in the lunar regolith 总被引：1，自引：0，他引：1
Lunar soils contain micrometer-sized mineral grains surrounded by thin amorphous rims. Similar features have been produced by exposure of pristine grains to a simulated solar wind, leading to the widespread belief that the amorphous rims result from radiation damage. Electron microscopy studies show, however, that the amorphous rims are compositionally distinct from their hosts and consist largely of vapor-deposited material generated by micrometeorite impacts into the lunar regolith. Vapor deposits slow the lunar erosion rate by solar wind sputtering, influence the optical properties of the lunar regolith, and may account for the presence of sodium and potassium in the lunar atmosphere. 相似文献
5.
Lunar samples contain mercury, which may be volatilized at lunar daytime temperatures. Such mercury may constitute part of the tenuous lunar atmosphere. If mercury can escape from the atmosphere by a nonthermal mechanism, an interior reservoir or exterior sources (such as meteorite infall or solar wind, or both) are required to replenish it. Core samples exhibit an increase in surface-related mercury with depth, which suggests that a cold trap exists below the surface. The orientation of rocks on the lunar surface may be inferred by differences in the amounts of surface-related mercury found on exterior and interior samples. 相似文献
6.
Tritium and argon radioactivities, attributable to galactic and solar cosmic-ray interactions, were measured in lunar soil and in three lunar rocks. The tritium in the soil, 325 +/- 17 disintegrations per minute per kilogram, is slightly higher than that in the rocks, 212 to 250 dpm/kg. For two rocks, the tritium was combined with the helium-3 in order to calculate exposure ages of 375 +/- 40 and 205 +/- 25 million years. The argon-37 radioactivities, 21.0 to 27.2 dpm/kg, and the argon-39 radioactivities, 12.1 to 16.4 dpm/kg, are slightly higher than those in stony meteorites. Higher exposure ages were obtained from the argon isotopes than from tritium and helium-3. On the basis of the known galactic cosmic-ray flux and the known cross section, at least half of the observed radioactivities are produced by solar cosmic rays. 相似文献
7.
Beryllium-10 (10Be) in excess of that expected from in situ cosmic ray spallation reactions is present in lunar surface soil 78481; its presence was revealed with a sequential leaching technique. This excess 10Be, representing only 0.7 to 1.1% of the total 10Be inventory, is associated with surface layers (<1 micrometer) of the mineral grains composing 78481. This excess 10Be and its association with surficial layers corresponds to (1.9 +/- 0.8) x 10(8) atoms per square centimeter, requiring a 10Be implantation rate of (2.9 +/- 1.2) x 10(-6) atoms per square centimeter per second on the surface of the Moon. The most likely site for the production of this excess (10)Be is the Sun's atmosphere. The 10Be is entrained into the solar wind and transported to the lunar surface. 相似文献
8.
Wetherill GW 《Science (New York, N.Y.)》1971,173(3995):383-392
Considerable information concerning lunar chronology has been obtained by the study of rocks and soil returned by the Apollo 11 and Apollo 12 missions. It has been shown that at the time the moon, earth, and solar system were formed, approximately 4.6 approximately 10(9) years ago, a severe chemical fractionation took place, resulting in depletion of relatively volatile elements such as Rb and Pb from the sources of the lunar rocks studied. It is very likely that much of this material was lost to interplanetary space, although some of the loss may be associated with internal chemical differentiation of the moon. It has also been shown that igneous processes have enriched some regions of the moon in lithophile elements such as Rb, U, and Ba, very early in lunar history, within 100 million years of its formation. Subsequent igneous and metamorphic activity occurred over a long period of time; mare volcanism of the Apollo 11 and Apollo 12 sites occurred at distinctly different times, 3.6 approximately 10(9) and 3.3 approximately 10(9) years ago, respectively. Consequently, lunar magmatism and remanent magnetism cannot be explained in terms of a unique event, such as a close approach to the earth at a time of lunar capture. It is likely that these phenomena will require explanation in terms of internal lunar processes, operative to a considerable depth in the moon, over a long period of time. These data, together with the low present internal temperatures of the moon, inferred from measurements of lunar electrical conductivity, impose severe constraints on acceptable thermal histories of the moon. Progress is being made toward understanding lunar surface properties by use of the effects of particle bombardment of the lunar surface (solar wind, solar flare particles, galactic cosmic rays). It has been shown that the rate of micrometeorite erosion is very low (angstroms per year) and that lunar rocks and soil have been within approximately a meter of the lunar surface for hundreds of millions of years. Future work will require sampling distinctly different regions of the moon in order to provide data concerning other important lunar events, such as the time of formation of the highland regions and of the mare basins, and of the extent to which lunar volcanism has persisted subsequent to the first third of lunar history. This work will require a sufficient number of Apollo landings, and any further cancellation of Apollo missions will jeopardize this unique opportunity to study the development of a planetary body from its beginning. Such a study is fundamental to our understanding of the earth and other planets. 相似文献
9.
The exposure of a typical complex lunar breccia to hydrogen after a thorough outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere. 相似文献
10.
For typical solar wind conditions, lunar magnetic anomalies with dipole moments m > 5 x 10(13) gauss-cubic centimeters will strongly deflect the solar wind, producing local plasma voids at the lunar surface. The correlation of the largest observed anomalies (m approximately 10(16) gauss-cubic centimeters) with unusual, relatively high albedo surface features may therefore imply that solar wind ion bombardment is an important determinant of the optical properties of the lunar surface. 相似文献
11.
The extent of the lunar atmosphere is severely limited by collision with the protons of the solar wind. 相似文献
12.
The last lava flow in the Hadley Rille area of Mare Imbrium, as inferred from an argon-40-argon-39 experiment on a plagioclase separate from the lunar basalt 15555, occurred 3.31+/-0.03x10(9) years ago. An argon-40-argon-39 experiment on a whole rock sample shows significant loss of radiogenic argon-40 and yields a well-defined, high-temperature plateau indicating a lower age of 3.22+/-0.03x10(9) years. A cosmic-ray exposure age of 90+/-10x10(6) years is determined from the ratio of spallogenic argon-38 to calcium. 相似文献
13.
The helium-4 solar wind flux during the Apollo 11 lunar surface excursion was (6.3 +/- 1.2) x 10(6) atoms per square centimeter per second. The solar wind direction and energy are essentially not perturbed by the moon. Evidence for a lunar solar wind albedo was found. 相似文献
14.
Gases trapped in individual vesicles in the volatile-rich basaltic glass "popping rock" were found to have the same carbon dioxide, helium-4, and argon-40 composition, but a variable 40Ar/36Ar ratio ( approximately 4000 to >/=40,000). The argon-36 is probably surface-adsorbed atmospheric argon; any mantle argon-36 trapped in the vesicles cannot be distinguished from an atmospheric contaminant. Consequently the 40Ar/36Ar ratios and 3He/36Ar ratios (1.45) determined are minimum estimates of the upper mantle composition. Heavy noble gas relative abundances in the mantle resemble solar noble gas abundance patterns, and a solar origin may be common to all primordial mantle noble gases. 相似文献
15.
Eberhardt P Geiss J Graf H Grögler N Krähenbühl U Schwaller H Schwarzmüller J Stettler A 《Science (New York, N.Y.)》1970,167(3918):558-560
Grain size and etching experiments show that the fine lunar material contains large amounts of trapped solar wind particles. Elemental and isotopic compositions of the noble gases in solar material and in the terrestrial atmosphere are significantly different, except for the Ar(36)/ Ar(38) and the Kr isotope ratios. Exposure ages of two rocks and of the fine material are between 380 and 510 x 10(6) years. Feldspar concentrates give K/Ar ages of 3220 and 3300 x 10(6) years, significantly higher than the unseparated rock. 相似文献
16.
Ion microprobe analyses show that solar wind nitrogen associated with solar wind hydrogen implanted in the first tens of nanometers of lunar regolith grains is depleted in 15N by at least 24% relative to terrestrial atmosphere, whereas a nonsolar component associated with deuterium-rich hydrogen, detected in silicon-bearing coatings at the surface of some ilmenite grains, is enriched in 15N. Systematic enrichment of 15N in terrestrial planets and bulk meteorites relative to the protosolar gas cannot be explained by isotopic fractionation in nebular or planetary environments but requires the contribution of 15N-rich compounds to the total nitrogen in planetary materials. Most of these compounds are possibly of an interstellar origin and never equilibrated with the 15N-depleted protosolar nebula. 相似文献
17.
The rare gas analysis of the lunar surface has lead to important conclusions concerning the moon. The large amounts of rare gases found in the lunar soil and breccia indicate that the solar atmosphere is trapped in the lunar soil as no other source of such large amounts of gas is known. The cosmogenic products indicate that the exposure ages of the 17 lunar rocks measured vary from 20 to 400 million years with some grouping of the ages. The most striking feature is the old potassium-argon age which for the 14 rocks analyzed varies from 2.5 to 3.8 billion years. It is concluded that Mare Tranquillitatis crystallized about 4 billion years ago from a molten state produced by a large meteorite impact or volcanic flow. 相似文献
18.
Morrison GH Gerard JT Kashuba AT Gangadharam EV Rothenberg AM Potter NM Miller GB 《Science (New York, N.Y.)》1970,167(3918):505-507
Results for multielement analysis of lunar soil and of seven rocks returned by Apollo 11 are presented. Sixty-six elements were determined with spark source mass spectrography and neutron activation. U. S. Geological Survey standard W-1 was used as a comparative stanadard. Results indicate an apparent uniformity of composition among the samples. Comparison with solar, meteoritic, and terrestrial abundances reveals depletiozt of volatile elements and enrichment of the rare earths titaniunm, zirconium, yttriuntm, and hafnium. Althouglh there is an overall similarity of the lunar material to basaltic achondrites amid basalts, the differences suggest detailed geochemical processes to the history of this material. 相似文献
19.
Ultrathin amorphous coatings on lunar dust grains 总被引：1，自引：0，他引：1
Bibring JP Duraud JP Durrieu L Jouret C Maurette M Meunier R 《Science (New York, N.Y.)》1972,175(4023):753-755
UItrathin amorphous coatings have been observed by high-voltage electron microscopy on micrometer-sized dust grains from the Apollo 11, Apollo 12, Apollo 14, and Luna 16 missions. Calibration experiments show that these coatings result from an "ancient" implantation of solar wind ions in the grains. This phenomenon has interdisciplinary applications concerning the past activity of the sun, the lunar albedo, the ancient lunar atmosphere and magnetic field, the carbon content of lunar soils, and lunar dynamic processes. 相似文献
20.
Lunar sample Preliminary Examination Team 《Science (New York, N.Y.)》1971,173(3998):681-693
The major findings of the preliminary examination of the lunar samples are as follows: 1) The samples from Fra Mauro base may be contrasted with those from Tranquillity base and the Ocean of Storms in that about half the Apollo 11 samples consist of basaltic rocks, and all but three Apollo 12 rocks are basaltic, whereas in the Apollo 14 samples only two rocks of the 33 rocks over 50 grams have basaltic textures. The samples from Fra Mauro base consist largely of fragmental rocks containing clasts of diverse lithologies and histories. Generally the rocks differ modally from earlier lunar samples in that they contain more plagioclase and contain orthopyroxene. 2) The Apollo 14 samples differ chemically from earlier lunar rocks and from their closest meteorite and terrestrial analogs. The lunar material closest in composition is the KREEP component (potassium, rare earth elements, phosphorus), "norite," "mottled gray fragments" (9) from the soil samples (in particular, sample 12033) from the Apollo 12 site, and the dark portion of rock 12013 (10). The Apollo 14 material is richer in titanium, iron, magnesium, and silicon than the Surveyor 7 material, the only lunar highlands material directly analyzed (11). The rocks also differ from the mare basalts, having much lower contents of iron, titanium, manganese, chromium, and scandium and higher contents of silicon, aluminum, zirconium, potassium, uranium, thorium, barium, rubidium, sodium, niobium, lithium, and lanthanum. The ratios of potassium to uranium are lower than those of terrestrial rocks and similar to those of earlier lunar samples. 3) The chemical composition of the soil closely resembles that of the fragmental rocks and the large basaltic rock (sample 14310) except that some elements (potassium, lanthanum, ytterbium, and barium) may be somewhat depleted in the soil with respect to the average rock composition. 4) Rocks display characteristic surface features of lunar material (impact microcraters, rounding) and shock effects similar to those observed in rocks and soil from the Apollo 11 and Apollo 12 missions. The rocks show no evidence of exposure to water, and their content of metallic iron suggests that they, like the Apollo 11 and Apollo 12 material, were formed and have remained in an environment with low oxygen activity. 5) The concentration of solar windimplanted material in the soil is large, as was the case for Apollo 11 and Apollo 12 soil. However, unlike previous fragmental rocks, Apollo 14 fragmental rocks possess solar wind contents ranging from approximately that of the soil to essentially zero, with most rocks investigated falling toward one extreme of this range. A positive correlation appears to exist between the solar wind components, carbon, and (20)Ne, of fragmental rocks and their friability (Fig. 12). 6) Carbon contents lie within the range of carbon contents for Apollo 11 and Apollo 12 samples. 7) Four fragmental rocks show surface exposure times (10 x 10(6) to 20 x 10(6) years) about an order of magnitude less than typical exposure times of Apollo 11 and Apollo 12 rocks. 8) A much broader range of soil mechanics properties was encountered at the Apollo 14 site than has been observed at the Apollo 11, Apollo 12, and Surveyor landing sites. At different points along the traverses of the Apollo 14 mission, lesser cohesion, coarser grain size, and greater resistance to penetration was found than at the Apollo 11 and Apollo 12 sites. These variations are indicative of a very complex, heterogeneous deposit. The soils are more poorly sorted, but the range of grain size is similar to those of the Apollo 11 and Apollo 12 soils. 9) No evidence of biological material has been found in the samples to date. 相似文献