• Observations and interpretations at Vredefort, Sudbury, and Chicxulub: Towards an empirical model of terrestrial impact basin formation

      Grieve, R. A. F.; Reimold, W. U.; Morgan, J.; Riller, U.; Pilkington, M. (The Meteoritical Society, 2008-01-01)
      The structural, topographic and other characteristics of the Vredefort, Sudbury, and Chicxulub impact structures are described. Assuming that the structures originally had the same morphology, the observations/interpretations for each structure are compared and extended to the other structures. This does not result in any major inconsistencies but requires that the observations be scaled spatially. In the case of Vredefort and Sudbury, this is accomplished by scaling the outer limit of particular shock metamorphic features. In the case of Chicxulub, scaling requires a reasoned assumption as to the formation mechanism of an interior peak ring. The observations/interpretations are then used to construct an integrated, empirical kinematic model for a terrestrial peak-ring basin. The major attributes of the model include: a set of outward-directed thrusts in the parautochthonous rocks of the outermost environs of the crater floor, some of which are pre-existing structures that have been reactivated during transient cavity formation; inward-directed motions along the same outermost structures and along a set of structures, at intermediate radial distances, during transient cavity collapse; structural uplift in the center followed by a final set of radially outward-directed thrusts at the outer edges of the structural uplift, during uplift collapse. The rock displacements on the intermediate, inward and innermost, outward sets of structures are consistent with the assumption that a peak ring will result from the convergence of the collapse of the transient cavity rim area and the collapse of the structural uplift.
    • Observations at terrestrial impact structures: Their utility in constraining crater formation

      Grieve, R. A. F.; Therriault, A. M. (The Meteoritical Society, 2004-01-01)
      Hypervelocity impact involves the near instantaneous transfer of considerable energy from the impactor to a spatially limited near-surface volume of the target body. Local geology of the target area tends to be of secondary importance, and the net result is that impacts of similar size on a given planetary body produce similar results. This is the essence of the utility of observations at impact craters, particularly terrestrial craters, in constraining impact processes. Unfortunately, there are few well-documented results from systematic contemporaneous campaigns to characterize specific terrestrial impact structures with the full spectrum of geoscientific tools available at the time. Nevertheless, observations of the terrestrial impact record have contributed substantially to fundamental properties of impact. There is a beginning of convergence and mutual testing of observations at terrestrial impact structures and the results of modeling, in particular from recent hydrocode models. The terrestrial impact record provides few constraints on models of ejecta processes beyond a confirmation of the involvement of the local substrate in ejecta lithologies and shows that Z-models are, at best, first order approximations. Observational evidence to date suggests that the formation of interior rings is an extension of the structural uplift process that occurs at smaller complex impact structures. There are, however, major observational gaps and cases, e.g., Vredefort, where current observations and hydrocode models are apparently inconsistent. It is, perhaps, time that the impact community as a whole considers documenting the existing observational and modeling knowledge gaps that are required to be filled to make the intellectual breakthroughs equivalent to those of the 1970s and 1980s, which were fueled by observations at terrestrial impact structures. Filling these knowledge gaps would likely be centered on the later stages of formation of complex and ring structures and on ejecta.
    • Olivine zoning and retrograde olivine-orthopyroxene-metal equilibration in H5 and H6 chondrites

      Reisener, R. J.; Goldstein, J. I.; Petaev, M. I. (The Meteoritical Society, 2006-01-01)
      Electron microprobe studies of several H5 and H6 chondrites reveal that olivine crystals exhibit systematic Fe-Mg zoning near olivine-metal interfaces. Olivine Fa concentrations decrease by up to 2 mol% toward zoned taenite + kamacite particles (formed after relatively small amounts of taenite undercooling) and increase by up to 2 mol% toward zoneless plessite particles (formed after ~200 degrees C of taenite undercooling). The olivine zoning can be understood in terms of localized olivine-orthopyroxene-metal reactions during cooling from the peak metamorphic temperature. The silicate-metal reactions were influenced by solid-state metal phase transformations, and the two types of olivine zoning profiles resulted from variable amounts of taenite undercooling at temperatures <700 degrees C. The relevant silicate-metal reactions are modeled using chemical thermodynamics. Systematic olivine Fe-Mg zoning adjacent to metal is an expected consequence of retrograde silicate-metal reactions, and the presence of such zoning provides strong evidence that the silicate and metallic minerals evolved in situ during cooling from the peak metamorphic temperature.
    • Olivine-dominated asteroids and meteorites: Distinguishing nebular and igneous histories

      Sunshine, Jessica M.; Bus, Schelte J.; Corrigan, Catherine M.; McCoy, Timothy J.; Burbine, Thomas H. (The Meteoritical Society, 2007-01-01)
      Melting models indicate that the composition and abundance of olivine systematically co-vary and are therefore excellent petrologic indicators. However, heliocentric distance, and thus surface temperature, has a significant effect on the spectra of olivine-rich asteroids. We show that composition and temperature complexly interact spectrally, and must be simultaneously taken into account in order to infer olivine composition accurately. We find that most (7/9) of the olivine-dominated asteroids are magnesian and thus likely sampled mantles differentiated from ordinary chondrite sources (e.g.,pallasites). However, two other olivine-rich asteroids (289 Nenetta and 246 Asporina) are found to be more ferroan. Melting models show that partial melting cannot produce olivine-rich residues that are more ferroan than the chondrite precursor from which they formed. Thus, even moderately ferroan olivine must have non-ordinary chondrite origins, and therefore likely originate from oxidized R chondrites or melts thereof, which reflect variations in nebular composition within the asteroid belt. This is consistent with the meteoritic record in which R chondrites and brachinites are rare relative to pallasites.
    • Olivine-phyric martian basalts: A new type of shergottite

      Goodrich, Cyrena Anne (The Meteoritical Society, 2002-12-01)
    • On estimating contributions of basin ejecta to regolith deposits at lunar sites

      Haskin, L. A.; Moss, W. E.; McKinnon, W. B. (The Meteoritical Society, 2003-01-01)
      We have developed a quantitative model for predicting characteristics of ejecta deposits that result from basin-sized cratering events. This model is based on impact crater scaling equations (Housen, Schmitt, and Holsapple 1983; Holsapple 1993) and the concept of ballistic sedimentation (Oberbeck 1975), and takes into account the size distribution of the individual fragments ejected from the primary crater. Using the model, we can estimate, for an area centered at the chosen location of interest, the average distribution of thicknesses of basin ejecta deposits within the area and the fraction of primary ejecta contained within the deposits. Model estimates of ejecta deposit thicknesses are calibrated using those of the Orientale Basin (Moore, Hodges, and Scott 1974) and of the Ries Basin (Hörz, Ostertag, and Rainey 1983). Observed densities of secondary craters surrounding the Imbrium and Orientale Basins are much lower than the modeled densities. Similarly, crater counts for part of the northern half of the Copernicus secondary cratering field are much lower than the model predicts, and variation in crater densities with distance from Copernicus is less than expected. These results suggest that mutual obliteration erases essentially all secondary craters associated with the debris surge that arises from the impacting primary fragments during ballistic sedimentation; if so, a process other than ballistic sedimentation is needed to produce observable secondary craters. Regardless, our ejecta deposit model can be useful for suggesting provenances of sampled lunar materials, providing information complementary to photogeological and remote sensing interpretations, and as a tool for planning rover traverses (e.g., Haskin et al. 1995, 2002).
    • On the origin of shocked and unshocked CM clasts in H-chondrite regolith breccias

      Rubin, A. E.; Bottke, W. F. (The Meteoritical Society, 2009-01-01)
      CM chondrite clasts that have experienced different degrees of aqueous alteration occur in H-chondrite and HED meteorite breccias. Many clasts are fragments of essentially unshocked CM projectiles that accreted at low relative velocities to the regoliths of these parent bodies. A few clasts were heated and dehydrated upon impact; these objects most likely accreted at higher relative velocities. We examined three clasts and explored alternative scenarios for their formation. In the first scenario, we assumed that the H and HED parent bodies had diameters of a few hundred kilometers, so that their high escape velocities would effectively prevent soft landings of small CM projectiles. This would imply that weakly shocked CM clasts formed on asteroidal fragments (family members) associated with the H and HED parent bodies. In the second scenario, we assumed that weakly shocked CM clasts were spall products ejected at low velocities from larger CM projectiles when they slammed into the H and HED parent bodies. In both cases, if most CM clasts turn out to have ancient ages (e.g., ~3.4-4.1 Ga), a plausible source for their progenitors would be outer main belt objects, some which may have been dynamically implanted 3.9 Ga ago by the events described in the so-called Nice model. On the other hand, if most CM clasts have recent ages (<200 Ma), a plausible source location for their parent body would be the inner main belt between 2.1-2.2 AU. In that case, the possible source of the CM-clasts progenitors parent fragments would be the breakup ~160 Ma ago of the parent body 170 km in diameter of the Baptistina asteroid family (BAF).
    • On the structure of mare basalt lava flows from textural analysis of the LaPaz Icefield and Northwest Africa 032 lunar meteorites

      Day, James M. D.; Taylor, Lawrence A. (The Meteoritical Society, 2007-01-01)
      Quantitative textural data for Northwest Africa (NWA) 032 and the LaPaz (LAP) mare basalt meteorites (LAP 02205, LAP 02224, LAP 02226, and LAP 02436) provide constraints on their crystallization and mineral growth histories. In conjunction with whole-rock and mineral chemistry, textural analysis provides powerful evidence for meteorite pairing. Petrographic observations and crystal size distribution (CSD) measurements of NWA 032 indicate a mixed population of slowly cooled phenocrysts and faster cooled matrix. LaPaz basalt crystal populations are consistent with a single phase of nucleation and growth. Spatial distribution patterns (SDP) of minerals in the meteorites highlight the importance of clumping and formation of clustered crystal frameworks in their melts, succeeded by continued nucleation and growth of crystals. This process resulted in increasingly poor sorting, during competition for growth, as the melt crystallized. Based on CSD and SDP data, we suggest a potential lava flow geometry model to explain the different crystal populations for NWA 032 and the LaPaz basalts. This model involves crystallization of early formed phenocrysts at hypabyssal depths in the lunar crust, followed by eruption and flow differentiation on the lunar surface. Lava flow differentiation would allow for formation of a cumulate base and facilitate variable cooling within the stratigraphy, explaining the varied textures and modal mineralogies of mare basalt meteorites. The model may also provide insight into the relative relationships of some Apollo mare basalt suites, shallow-level crystal fractionation processes, and the nature of mare basalt volcanism over lunar history.
    • One meteorite less from Vietnam

      Rochette, P. (The Meteoritical Society, 2002-12-01)
      Among the four declared meteorites from Vietnam, the two most recent ones--Phuoc-Binh (1941) and Fuc Bin (1971)--appear to be the same, following a visit to the Hanoi museum and an analysis of the literature. Phuoc-Binh (L5) with a fall date of 1941 July 18 should be the correct entry.
    • One year closure of the Cosmic Dust Lab at NASA Johnson Space Center

      Zolensky, Michael (The Meteoritical Society, 2005-01-01)
    • Opaque minerals in chondrules and fine-grained chondrule rims in the Bishunpur (LL3.1) chondrite

      Lauretta, D. S.; Buseck, P. R. (The Meteoritical Society, 2003-01-01)
      We present a detailed petrographic and electron microprobe study of metal grains and related opaque minerals in the chondrule interiors and rims of the Bishunpur (LL3.1) ordinary chondrite. There are distinct differences between metal grains that are completely encased in chondrule interiors and those that have some portion of their surface exposed outside of the chondrule boundary, even though the two types of metal grains can be separated by only a few microns. Metal grains in chondrule interiors exhibit minor alteration in the form of oxidized P-, Cr-, and Si-bearing minerals. Metal grains at chondrule boundaries and in chondrule rims are extensively altered into troilite and fayalite. The results of this study suggest that many metal grains in Bishunpur reacted with a type-I chondrule melt and incorporated significant amounts of P, Cr, and Si. As the system cooled, some metal oxidation occurred in the chondrule interior, producing metal-associated phosphate, chromite, and silica. Metal that migrated to chondrule boundaries experienced extensive corrosion as a result of exposure to the external atmosphere present during chondrule formation. It appears that chondrule- derived metal and its corrosion products were incorporated into the fine-grained rims that surround many type-I chondrules, contributing to their Fe-rich compositions. We propose that these fine- grained rims formed by a combination of corrosion of metal expelled from the chondrule interior and accretion of fine-grained mineral fragments and microchondrules.
    • OpenOrb: Open-source asteroid orbit computation software including statistical ranging

      Granvik, M.; Virtanen, J.; Oszkiewicz, D.; Muinonen, K. (The Meteoritical Society, 2009-01-01)
      We are making an open-source asteroid orbit computation software package called OpenOrb publicly available. OpenOrb is built on a well-established Bayesian inversion theory, which means that it is to a large part complementary to orbit-computation packages currently available. In particular, OpenOrb is the first package that contains tools for rigorously estimating the uncertainties resulting from the inverse problem of computing orbital elements using scarce astrometry. In addition to the well-known least-squares method, OpenOrb also contains both Monte-Carlo (MC) and Markov-Chain MC (MCMC; Oszkiewicz et al. [2009]) versions of the statistical ranging method. Ranging allows the user to obtain sampled, non-Gaussian orbital-element probability-density functions and is therefore optimized for cases where the amount of astrometry is scarce or spans a relatively short time interval. Ranging-based methods have successfully been applied to a variety of different problems such as rigorous ephemeris prediction, orbital element distribution studies for transneptunian objects, the computation of invariant collision probabilities between near-Earth objects and the Earth, detection of linkages between astrometric asteroid observations within an apparition as well as between apparitions, and in the rigorous analysis of the impact of orbital arc length and/or astrometric uncertainty on the uncertainty of the resulting orbits. Tools for making ephemeris predictions and for classifying objects based on their orbits are also available in OpenOrb. As an example, we use OpenOrb in the search for candidate retrograde and/or high-inclination objects similar to 2008 KV42 in the known population of transneptunian objects that have an observational time span shorter than 30 days.
    • Opportunities for the stratospheric collection of dust from short-period comets

      Messenger, S. (The Meteoritical Society, 2002-01-01)
      We have identified four comets which have produced low velocity Earth-crossing dust streams within the past century: 7P/Pons-Winnecke, 26P/Grigg-Skjellerup, 73P/Schwassmann-Wachmann 3, and 103P/Hartley 2. These comets have the rare characteristics of low eccentricity, low inclination orbits with nodes very close to 1 AU. Dust from these comets is directly injected into Earth-crossing orbits by radiation pressure, unlike the great majority of interplanetary dust particles collected in the stratosphere which spend millennia in space prior to Earth-encounter. Complete dust streams from these comets form within a few decades, and appreciable amounts of dust are accreted by the Earth each year regardless of the positions of the parent comets. Dust from these comets could be collected in the stratosphere and identified by its short space exposure age, as indicated by low abundances of implanted solar wind noble gases and/or lack of solar flare tracks. Dust from Grigg-Skjellerup probably has the highest concentration at Earth orbit. We estimate that the proportion of dust from this comet reaches at least several percent of the background interplanetary dust flux in the >40 micrometer size range during April 23-24 of 2003.
    • Oral histories in meteorites and planetary science: X. Ralph B. Baldwin

      Marvin, U. B. (The Meteoritical Society, 2003-01-01)
      In this interview, Ralph Baldwin describes how he earned his Ph.D. in astronomy and then, early in his career, became interested in the Moon and the origin of its craters. When he concluded that the craters were formed by meteorite impacts rather than by volcanism, he faced great difficulties in finding an audience or a publisher. During World War II, he helped to design and develop operating specifications for the radio proximity fuze which has been credited with shortening the War by at least one year. Subsequently, he joined the family firm, The Oliver Machinery Company, in Grand Rapids, Michigan. He pursued his lunar studies on nights and weekends and wrote his first book, The Face of the Moon, which was published in 1949. Sales were poor, but the book was read by Harold degrees C. Urey, who sought out Baldwin for discussions about the Moon, and by Peter M. Millman, in Ottawa, who prompted Dr. Carlyle S. Beals, the Dominion Astronomer, to begin the highly successful search for impact craters on the Canadian Shield. With his second book, The Measure of the Moon, published in 1963, Baldwin became recognized as a leading authority on the Moon and on planetary processes in general. He is the only scientist other than Eugene M. Shoemaker to whom the Meteoritical Society has presented both its Leonard Medal, in 1986, and its Barringer Medal, in 2000, and who also received the G. K. Gilbert Award, in 1986, from the Planetary Sciences Division of the Geologial Society of America.
    • Oral histories in meteorites and planetary science: XI. Masatake Honda

      Marvin, U. B. (The Meteoritical Society, 2003-01-01)
      Masatake Honda majored in inorganic chemistry at the University of Tokyo and then pursued graduate studies in geochemistry. In 1943, he completed his first research project, which yielded new data on the behavior of strontium in carbonates. He then spent the next two years as a technical officer in the Japanese Imperial Navy. While on duty, he gained expertise in the important new field of ion exchange methods, which he ultimately chose as the topic for his Ph.D. thesis and then expanded into a book. In 1955, Honda traveled to Switzerland and spent a year in research laboratories at Bern and Zrich. He then joined Professor James R. Arnold at Princeton University and soon began focusing his research on cosmic-ray produced nuclides in meteorites. Two years later, he accompanied Dr. Arnold to the University of California at La Jolla where they joined the research group of Professor Harold degrees C. Urey. Honda developed techniques for measuring terrestrial ages of meteorites and showed that most of them have survived weathering for vastly longer periods than had been anticipated. After spending nearly eight years abroad, he returned to Japan in 1962 as a full professor at the University of Tokyo. During the Apollo missions, he performed research on cosmogenic nuclides in lunar rocks, surface soils, and deep drill cores. In the same period, he studied terrestrial histories of numerous Antarctic meteorites. In 1992, he retired from his professorship but he continues to carry on his research and to publish papers. In 1987, the Meteoritical Society presented its Leonard Medal to Masatake Honda for his pioneering work in establishing the abundances and production rates of stable, long-lived, and short-lived nuclides by cosmic irradiation of meteorites and lunar samples.
    • Oral histories in meteorites and planetary science: XII. Gerald J. Wasserburg

      Marvin, U. B. (The Meteoritical Society, 2004-01-01)
      In this interview, Gerald J. (Jerry) Wasserburg recounts how he entered the Geology Department at the University of Chicago in 1948 but switched to a major in physics, while maintaining links with geology, particularly geochemistry. He earned his Ph.D. in 1954 with a thesis on the new technique of potassium-argon dating under Harold degrees C. Urey and Mark Inghram. After spending a year at Chicago as a post-doctoral research fellow with Urey, he joined the faculty at the California Institute of Technology where he ultimately advanced to the title of John D. MacArthur Professor of Geology and Geophysics. In the early 1960s, Wasserburg sought to achieve unprecedented sensitivity and precision in isotopic measurements by designing and directing the construction of the first digital output with magnet switching and on-line processing computercontrolled mass spectrometer. He promptly named his unique instrument, Lunatic I, and his laboratory, the Lunatic Asylum. Using that instrument and later ones, Wasserburg and his research group identified specific nucleosynthetic processes that produced isotopic anomalies in inclusions found in meteorites; investigated the origin and evolution of planetary bodies from the solar nebula; dated the oldest components in meteorites and in terrestrial and lunar rocks; and studied the oxygen in presolar grains and the astrophysical models of AGB stars. In addition to his labors in science, he served on policy-making committees and worked with other members to seek the highest standards for receiving and processing lunar samples and other planetary materials, and to forestall the elimination of the final three Apollo missions. Wasserburg has received many honors, including several honorary doctorates from universities at home and abroad, and the prestigious Crafoord Prize bestowed on him in 1986 by the Royal Swedish Academy of Sciences. In 1975, the Meteoritical Society awarded him its Leonard Medal and in 1987-1988, he served as President of the Society.
    • Oral histories in meteorites and planetary science: XIII. Fred L. Whipple

      Marvin, U. B. (The Meteoritical Society, 2004-01-01)
      Born in Red Oak, Iowa, in 1906, Fred Lawrence Whipple earned his Ph.D. in astronomy at the University of California at Berkeley in 1931. He immediately accepted a position at the Harvard College Observatory and remained at Harvard throughout his career. In 1950, he was appointed to the Phillips Professorship in the Department of Astronomy, and in 1955, he began serving concurrently as the Director of the Smithsonian Astrophysical Observatory when it moved from Washington, D.C. to Cambridge, Massachusetts. In the 1930s, Whipple established the Harvard Meteor Project in which two cameras, 26 miles apart, simultaneously photographed the same meteors, for which he invariably derived elliptical orbits indicative of their origin within the solar system. In 1950, Whipple introduced his dirty snowball model of comet nuclei, which soon became widely accepted and was fully confirmed in 1986 by close-up images of comet Halley taken by the European Space Agencys Giotto spacecraft. Keenly anticipating the orbiting of satellites during the International Geophysical Year (July 1, 1957-December 31, 1958), Whipple won contracts to build a worldwide network of telescopic cameras for satellite tracking. At least one of the cameras was ready in time to photograph the Soviet Unions Sputnik I satellite in October 1957, and all 12 stations were in operation by midsummer of 1958. For his leadership role in this project, President John Kennedy honored Fred L. Whipple in June 1963 with the Presidents Award for Distinguished Public Service. In the 1960s, Whipple collaborated with astronomers at the University of Arizona to build a new observatory on Mt. Hopkins, 40 miles south of Tucson. Two of the most innovative instruments installed there for astrophysical research were the worlds largest gamma-ray detector and the Multiple-Mirror Telescope. In 1982, the Mt. Hopkins Observatory was rededicated as the Fred Lawrence Whipple Observatory. Although he retired in 1973, Whipple was present at the dedication and until 2003, he continued to actively participate in research projects. At present, he is anticipating the return of the Stardust mission to comet Wild 2, which will bring back to Earth samples of the comet and of interstellar dust. It is scheduled to arrive in 2006, the year of Fred Whipples 100th birthday. Among his many honors, Fred Whipple received the Leonard Medal from the Meteoritical Society in 1970 at its meeting hosted by the Goddard Space Flight Center, in Skyland, Virginia.
    • Oral histories in meteoritics and planetary science: IX. Heinrich Wänke

      Marvin, Ursula B. (The Meteoritical Society, 2002-12-01)
      In this interview, Heinrich Wänke, a nuclear physicist, describes how he first encountered meteorite studies in 1953 when, after finishing his Ph.D. thesis in Vienna, he joined the research group of Professor Friedrich Paneth at the University of Durham, England. There, he worked on problems relating to uranium-helium ages of iron meteorites. A year later, Wänke moved with Paneth to the Max-Planck-Institut für Chemie at Mainz in Germany. He continued meteorite research but also conducted experiments to measure noble gases in the stratosphere, a project that brought him to America in 1956 where he first met Professor Harold C. Urey, with whom he formed a lasting friendship. After Paneth's early death in 1958, Wänke remained at the Institute in Mainz and pursued research on topics such as the isotopic compositions of cosmogenic noble gases in iron meteorites and the abundances of primordial rare gases implanted by solar wind particles in brecciated stony meteorites. In 1969, Wänke was appointed to fill Paneth's position as a director as the Max-Planck-Institut für Chemie just in time for him to lead a wide spectrum of research projects on the lunar rocks and soils. Froom the geochemical evidence these studies provided, he theorized on the formation of the Moon by the giant impact hypothesis, and proposed a two-component model for the cosmic composition of the Earth's mantle. His group also investigated the isotopic chemistry of martian meteorites and its hearing on the origin and evolution of Mars, which he viewed as a cored planet that underwent early differentiation without subsequent convective homogenization. In 1980, the Meteoritical Society awarded the Leonard Medal to Heinrich Wänke for his numerous contribution of fundamental importance to meteoritics and planetary science.
    • Oral histories in meteoritics and planetary science: V. Brian Mason

      Marvin, Ursula B. (The Meteoritical Society, 2002-12-01)
      In this interview, Brian Mason describes the sudden awakening of his interest in meteorites during his student days at Canterbury College in New Zealand when he read a paper on the cosmic abundance of the elements by Victor M. Goldschmidt. Subsequently, he won a scholarship for graduate study abroad and wrote to Goldschmidt asking if he could do a thesis with him in Norway. Shortly after he began his research in Oslo, he fled the city, ahead of the German invasion of Norway, and completed his doctorate in Stockholm with a thesis on the iron-manganese minerals of the Långban Mine. After the war he taught for 3 years at Canterbury College where he gave courses on mineralogy and geology (into which he inserted lectures on geochemistry) and led students in extensive field studies. In 1947, Mason accepted a professorship of mineralogy at Indiana University. While there, he wrote the landmark book, Principles of Geochemistry, which appeared in 1952. The following year he moved to New York City where he served as the Curator of Minerals at the American Museum of Natural History and an adjunct professor at Columbia University. He became fascinated with the museum's meteorite collection and discussed meteorites in his lectures, which inspired some of his outstanding students to enter the field. During a sabbatical year he spent as a Fulbright Professor in Japan, he gave an advanced level seminar on meteorites and based his book, Meteorites, on his lecture notes. Mason developed a rapid method of optically classifying chondritic meteorites that he applied to major collections in many countries, thus enabling curators to replace uninformative labels such as "stone" or "chondrite" with species names, and to recognize which of their meteorites were rare types demanding serious study. In 1965 he moved to the Smithsonian Institution in Washington, D.C. where he remained for the rest of his career. Early in 1968, he collected specimens from the spectacular fall of the Allende meteorite in Mexico, which proved to be a carbonaceous chondrite containing rare types of inclusions enriched in calcium and aluminum. His analyses showed how these incusions could be divided into groups on the basis of their differing rare earth element patterns. Mason's studies of Allende continued while he investigated lunar samples returned by the Apollo missions and coauthored a book on them. Beginning in the latter 1970s, he applied his rapid classification of stony meteorites to the large numbers of specimens collected each year by U.S. teams on the Antarctic ice sheet. In 1992 he capped his career with a biography of Victor M. Goldschmidt. In recognition of his many fundamental contributions, The Meteoritical Society honored Brian Mason with its Leonard Medal at its meeting in 1972 at the University of Chicago.
    • Oral histories in meteoritics and planetary science: VI. Stuart Ross Taylor

      Marvin, Ursula B. (The Meteoritical Society, 2002-12-01)
      In this interview, Ross Taylor describes how his interest in planetary science was aroused by proofreading Brian Mason's book on geochemistry. Born and raised in New Zealand, Ross majored in chemistry at Canterbury College in Christchurch. While there, he took a course in geology and was strongly tempted to change his major, but he resolved the problem by becoming a geochemist. For his doctoral studies, Ross joined Mason at Indiana University where he learned the basics of trace element analysis on the emission spectrograph. Subsequently, he set up emission spectrographic laboratories and used them to pursue his research at Oxford University and the University of Cape Town. As techniques became more sensitive, he set up a spark-source mass spectrograph at the Australian National University in Canberra. Ross always has retained an interest in terrestrial rocks, but he is most widely known for his investigations of tektites and lunar rocks. He became one of the earliest and strongest advocates of tektites as molten terrestrial sediments sent aloft by high-energy impacts. As a member of the preliminary examination team that analyzed the samples returned by the Apollo missions, Ross gained an intimate knowledge of lunar chemistry and petrology and wrote three books about the Moon. He also has written a book about the chemical evolution of the solar system, a topic on which such rapid progress was made in 10 years that his second edition is practically a different book from the first one. Ross has written Destiny or Chance, a philosophical consideration of the likelihood that as sentient beings we may well be alone in the universe. Ross served as the president of The Meteoritical Society in 1989 and 1990, and at its annual meeting in Dublin, Ireland, in 1998, the Society presented him with its Leonard Medal.