Experimental petrology of lunar material: the nature of mascons, seas, and the lunar interior

One-atmosphere melting data show that Apollo 11 samples are near cotectic. Melting relations at pressures up to 35 kilobars show that clinopyroxenite or amphibole peridotite are possible lunar interiors. Mascons cannot be eclogite; they may be ilmenite accumulate. Hot lunar surface material will boil off alkalis.     

U.s. Universities and the world food problem

The imponderable now is time. Certainly, it is in short supply if we hope to improve the world's prospects for food production. The requisite scientific skills that can contribute to greater world agricultural production exist in a uniquely concentrated form in the U.S. universities. Incentives for increased university involvement in technical assistance created by the International Development and Food Assistance Act of 1975 will not become effective until a mechanism which guarantees adequate and long-term funding is established. A continuing dialogue to define the nature and scope of needed reforms is necessary if maximum involvement of U.S. scientists in agricultural technical assistance is to be realized. Such involvement is vital in meeting the food needs of the developing world.     

New Horizons in Medical Research

From the above it is seen that the U. S. Public Health Service Research Grants program represents a sincere and continuing effort to supply Federal funds for the support of necessary additional research in the fields of medical and related sciences without interposing any degree of government restriction, control, supervision, or regimentation. The program is a scientific one, scientific guidance of which lies wholly in the hands of scientists.     

Genetics. FDA races in wrong direction

Despite recent genetic evidence and the promise of individualized medicine, there is a continuing interest in using self-identified categories of race and ethnicity as variables in scientific and medical research. The U.S. Food and Drug Administration recently proposed a standardized approach for the collection of race and ethnicity data in clinical trials. We believe that this move fails to acknowledge new scientific data and recommend that relevant data from individuals be collected and used rather than broad group statistics. We also encourage that increased funding be committed to this important issue.     

上海农业专家现状浅析

通过对上海各农业机构提供的具有高级职称科技人员资料的统计分析,表明:上海农业专家专业分布面广,但缺少都市型农业人才和高新技术研究人才;专家集中在科研单位,在科技推广部门较少;在职称评定中,重学历但不唯学历;上海将有70％的农业专家在5年内退休,所以必须迅速构筑上海农业高级人才高地。提出,建设上海自己的都市农业研究生基地,为青年科技人员成才创造一个宽松的竞争氛围,选拔和造就一大批青年农业高级专家,注意在年富力强的中年农业科技人才中晋升高级农业专家;应当制定条例,明确延聘专家的主要工作是带教青年科技人才等对策。     

Specific heats of lunar surface materials from 90 to 350 degrees Kelvin

The specific heats of lunar samples 10057 and 10084 returned by the Apollo 11 mission have been measured between 90 and 350 degrees Kelvin by use of an adiabatic calorimeter. The samples are representative of type A vesicular basalt-like rocks and of finely divided lunar soil. The specific heat of these materials changes smoothly from about 0.06 calorie per gram per degree at 90 degrees Kelvin to about 0.2 calorie per gram per degree at 350 degrees Kelvin. The thermal parameter gamma=(kpC-(1/2) for the lunar surface will accordingly vary by a factor of about 2 between lunar noon and midnight.     

浅谈如何进一步调动青年科技人员工作积极性

如何营造良好的科研环境氛围,加强对青年科技人员的引导和培养,进而提高青年科技人员工作积极性,是科研单位迫切需要解决的问题,针对这一问题,文章从政策支持、项目申请、多元化培养等角度提出了解决的政策,以鼓励青年科技人员提高工作积极性,重视理论成果向现实生产力转化,为服务"三农"多作贡献。     

Surface-related mercury in lunar samples

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.     

Lunar atmosphere as a source of argon-40 and other lunar surface elements

The lunar atmosphere is the likely source of excess argon-40 in lunar surface material; about 8.5 percent of the argon-40 released into the lunar atmosphere will be implanted in the surface material by photoionization and subsequent interaction with fields in the solar wind. The atmosphere is also likely to be the source of other unexpected surface elements or of solar wind elements that impact from non-solar wind directions.     

Compressibilities of lunar crystalline rock, microbreccia, and fines to 40 kilobars

The compressibilities of three lunar samples were studied at room temperature from 0 to 40 kilobars. The samples were a fine-grained vesicular crystalline rock (type A), a microbreccia (type C), and fines (type D). All samples were porous. The microbreccia and fines were quite compressible at all pressures; the compressibility of the crystalline rock was somewhat less, being 8.4 megabar(-1) at 1 atmosphere and 1.5 megabar(-1) at 35 kilobars. Some porosity appeared to remain in the samples at all pressures. Thus the pressure-volume data derived from these samples may be representative of porous surface and near-surface material in the vicinity of the Apollo 11 landing site but may not be representative of lunar material at depth.     

Of time and the moon

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.     

Water vapor from a lunar breccia: implications for evolving planetary atmospheres

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.     

Apollo 15 Geochemical X-ray Fluorescence Experiment: Preliminary Report

Although only part of the information from the x-ray fluorescence geochemical experiment has been analyzed, it is clear that the experiment was highly successful. Significant compositional differences among and possibly within the maria and highlands have been detected. When viewed in the light of analyzed lunar rocks and soil samples, and the data from other lunar orbital experiments (in particular, the Apollo 15 gamma-ray spectroscopy experiment), the results indicate the existence of a differential lunar highland crust, probably feldspathic. This crust appears to be related to the plagioclase-rich materials previously found in the samples from Apollo 11, Apollo 12, Apollo 14, Apollo 15, and Luna 16.     

Thermoluminescence of lunar samples

Appreciable natural thermoluminescence with glow curve peaks at about 350 degrees centigrade for lunar fines and breccias and above 400 degrees centigrade for crystalline rocks has been recognized in lunar samples. Plagioclase has been identified as the principal carrier of thermoluminescence, and the diference in peak temperatures indicates compositional or structural differences between the feldspars of the different rock types. The present thermoluminescence in the lunar samples is probably the result of a dynamic equilibrium between acquisition from radiation and loss in the lunar thermal environment. A progressive change in the glow curves of core samples with depth below the surface suggests the use of thermoluminescence disequilibrium to detect surfaces buried by recent surface activity, and it also indicates that the lunar diurnal temperature variation penetrates to at least 10.5 centimeters.     

Rubidium-strontium age and elemental and isotopic abundances of some trace elements in lunar samples

Data on six lunar crystalline rocks give an apparent Rb-Sr isochron age of 4.42 +/- 0.24 x 10(9) years (95 percent confidence limits) and initial (87)Sr/(86)Sr ratio similar to that in a basaltic achondrite. Relationships between K, Rb, Sr, and Ba and depletion of Eu in these samples point to plagioclase separation from the melts that produced these rocks. The abundance of (157)Gd in the three lunar samples is similar to terrestrial abundance within < 0.2 percent, thus setting a limit of < 6 x 10(15) neutrons per square centimeter for the integrated thermal neutron flux difference between lunar and terrestrial materials.     

Luminescence and reflectance of tranquillity samples: effects of irradiation and vitrification

Luminescence measurements of Tranquillity samples indicate that energy efficiencies for excitation by protons and ultraviolet are in the range 10(-6) or below; natural and induced thermoluminescence is even weaker. If these samples are typical, lunar surface luminescence cannot occur at reported levels. Comparison of proton luminescence spectra from the exterior and interior of rocks and fine fragments provides evidence of solar wind impingement on the moon's surface. Spectral reflectance and albedo measurements of fresh rock powders before and after both laboratory proton irradiation and fusion indicate that vitrification may be an important mechanism of lunar darkening.     

Public health. Grand Challenges in Global Health

This week an international panel announces a list of 14 Grand Challenges in Global Health, and scientists throughout the world will be invited to submit grant proposals to pursue them with funds provided by the Bill and Melinda Gates Foundation. We describe the characteristics of these challenges and the process by which they were formulated and selected after receiving over 1000 responses to a "call for ideas" from the scientific community.     

Luminescence of apollo 11 lunar samples

Luminescence measurements were made of four lunar rocks, two terrestrial rocks (granite and gabbro), and one terrestrial mineral (willemite) by comparing the spectral curves with the curve of a barium sulfate standard. Efficiencies with 3000 angstrom excitation were < 6 x 10(-5) for the lunar samples, < 8 x 10(-5) for gabbro of very similar composition to the lunar samples, approximately 10(-4) for granite, and approximately 2 X 10(-2) for willemite. If these are typical values for other ultraviolet excitation wavelengths, the Apollo 11 site appears to contribute little to the observed lunar luminescence.     

Planetary science. Nitrogen on the moon

The nitrogen isotopic compositions seen in lunar soils have long been a mystery to planetary scientists. As Becker discusses in his Perspective, new techniques, such as the depth profiling of mineral grains reported by Hashizume et al., are now shedding some light on the matter, allowing some theories to be excluded. Nevertheless, the relative role of the solar wind and other processes remains hotly debated.     

Isotopic composition of rare gases in lunar samples

Data from total melt and step-by-step heating experiments on the Apollo 11 lunar samples suggest a close affinity between lunar and meteoritic rare gases. Trapped neon-20/neon-22 ratios range from 11.5 to approximately 15, resembling those for the gas-rich meteorites. Trapped krypton and xenon in the lunar fines and in the carbonaceous chondrites are similar except for an interesting underabundance of the heavy isotopes in both lunar gases which suggests that the fission component found in carbonaceous chondrites is depleted in lunar material. Spallation gases are in most cases quite close to meteoritic spallation gases in isotopic composition.