Proceedings of the Geophysical Laboratory/Lawrence Radiation Laboratory Cratering Symposium

Energy Technology Data Exchange (ETDEWEB)

Nordyke, Milo D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

1961-10-01

The geological papers in this morning's session will deal descriptively with surficial features and end products of impact craters caused by meteorite falls. Such items as breccia, structural deformation, normal and inverse stratigraphy, glass (fused rock), and coesite will frequently be mentioned. Meteor and explosion crater data are presented.

Ar-Ar dating techniques for terrestrial meteorite impacts

Science.gov (United States)

Kelley, S. P.

2003-04-01

The ages of the largest (>100 km) known impacts on Earth are now well characterised. However the ages of many intermediate sized craters (20-100 km) are still poorly known, often the only constraints are stratigraphic - the difference between the target rock age and the age of crater filling sediments. The largest impacts result in significant melt bodies which cool to form igneous rocks and can be dated using conventional radiometric techniques. Smaller impacts give rise to thin bands of melted rock or melt clasts intimately mixed with country rock clasts in breccia deposits, and present much more of a challenge to dating. The Ar-Ar dating technique can address a wide variety of complex and heterogeneous samples associated with meteorite impacts and obtain reasonable ages. Ar-Ar results will be presented from a series of terrestrial meteorite impact craters including Boltysh (65.17±0.64 Ma, Strangways (646±42 Ma), and St Martin (220±32 Ma) and a Late Triassic spherule bed, possibly representing distal deposits from Manicouagan (214±1 Ma) crater. Samples from the Boltysh and Strangways craters demonstrate the importance of rapid cooling upon the retention of old ages in glassy impact rocks. A Late Triassic spherule bed in SW England is cemented by both carbonate and K-feldspar cements allowing Ar-Ar dating of fine grained cement to place a mimimum age upon the age of the associated impact. An age of 214.7±2.5 Ma places the deposit with errors of the age of the Manicouagan impact, raising the possibility that it may represent a distal deposit (the deposit lay around 2000 km away from the site of the Manicouagan crater during the Late Triassic). Finally the limits of the technique will be demonstrated using an attempt to date melt rocks from the St Martin Crater in Canada.

Large meteorite impacts: The K/T model

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Bohor, B. F.

1992-01-01

The Cretaceous/Tertiary (K/T) boundary event represents probably the largest meteorite impact known on Earth. It is the only impact event conclusively linked to a worldwide mass extinction, a reflection of its gigantic scale and global influence. Until recently, the impact crater was not definitively located and only the distal ejecta of this impact was available for study. However, detailed investigations of this ejecta's mineralogy, geochemistry, microstratigraphy, and textures have allowed its modes of ejection and dispersal to be modeled without benefit of a source crater of known size and location.

Aboriginal oral traditions of Australian impact craters

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Hamacher, Duane W.; Goldsmith, John

2013-11-01

In this paper we explore Aboriginal oral traditions that relate to Australian meteorite craters. Using the literature, first-hand ethnographic records and field trip data, we identify oral traditions and artworks associated with four impact sites: Gosses Bluff, Henbury, Liverpool and Wolfe Creek. Oral traditions describe impact origins for Gosses Bluff, Henbury and Wolfe Creek Craters, and non-impact origins for Liverpool Crater, with Henbury and Wolfe Creek stories having both impact and non-impact origins. Three impact sites that are believed to have been formed during human habitation of Australia -- Dalgaranga, Veevers, and Boxhole -- do not have associated oral traditions that are reported in the literature.

Meteor Crater, AZ

Science.gov (United States)

2002-01-01

The Barringer Meteorite Crater (also known as 'Meteor Crater') is a gigantic hole in the middle of the arid sandstone of the Arizona desert. A rim of smashed and jumbled boulders, some of them the size of small houses, rises 50 m above the level of the surrounding plain. The crater itself is nearly a 1500 m wide, and 180 m deep. When Europeans first discovered the crater, the plain around it was covered with chunks of meteoritic iron - over 30 tons of it, scattered over an area 12 to 15 km in diameter. Scientists now believe that the crater was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 50 m across, weighed roughly 300,000 tons, and was traveling at a speed of 65,000 km per hour. This ASTER 3-D perspective view was created by draping an ASTER bands 3-2-1image over a digital elevation model from the US Geological Survey National Elevation Dataset.This image was acquired on May 17, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along

Combining meteorites and missions to explore Mars.

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McCoy, Timothy J; Corrigan, Catherine M; Herd, Christopher D K

2011-11-29

Laboratory studies of meteorites and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a martian origin came with the discovery of trapped atmospheric gases in one meteorite. Since then, the study of martian meteorites and findings from missions have been linked. Although the meteorite source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most martian meteorites are young ( 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from martian meteorites conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the meteorites is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential.

Evidence for a Meteoritic Component in Impact Melt Rock from the Chicxulub Structure

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Koeberl, Christian; Sharpton, Virgil L.; Schuraytz, Benjamin C.; Shirey, Steven B.; Blum, Joel D.; Marin, Luis E.

1994-01-01

The Chicxulub structure in Yucatan, Mexico, has recently been recognized as a greater then 200-km-diameter multi-ring impact crater of K-T boundary age. Crystalline impact melt rocks and breccias from within the crater, which have compositions similar to those of normal continental crustal rocks and which show shock metamorphic effects, have been studied for trace element and Re-Os isotope compositions. Re-Os isotope systematics allow the sensitive and selective determination of an extraterrestrial component in impact-derived rocks. A melt rock sample shows elevated iridium concentrations, an osmium concentration of 25 ppb, and a low Os-187/Os-188 ratio of 0.113, which are incompatible with derivation from the continental crust. Even though the Os-187/Os-188 ratio is slightly lower than the range so far measured in meteorites, a mantle origin seems unlikely for mass balance reasons and because the cratering event is unlikely to have excavated mantle material. The data support the hypothesis of a heterogeneously distributed meteoritic component in the Chicxulub melt rock. A sample of impact glass from the Haitian K-T boundary at Beloc yielded about 0.1 ppb osmium and an Os-187/0s-188 ratio of 0.251, indicating the presence of a small meteoritic component in the impact ejecta as well.

Goat paddock cryptoexplosion crater, Western Australia

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Harms, J.E.; Milton, D.J.; Ferguson, J.; Gilbert, D.J.; Harris, W.K.; Goleby, B.

1980-01-01

Goat Paddock, a crater slightly over 5 km in diameter (18??20??? S, 126??40???E), lies at the north edge of the King Leopold Range/Mueller Range junction in the Kimberley district, Western Australia (Fig. 1). It was noted as a geological anomaly in 1964 during regional mapping by the Bureau of Mineral Resources, Geology and Geophysics and the Geological Survey of Western Australia. The possibility of its being a meteorite impact crater has been discussed1, although this suggestion was subsequently ignored2. Two holes were drilled by a mining corporation in 1972 to test whether kimberlite underlay the structure. Here we report the findings of five days of reconnaissance in August 1979 which established that Goat Paddock is a cryptoexplosion crater containing shocked rocks and an unusually well exposed set of structural features. ?? 1980 Nature Publishing Group.

An anthropogenic origin of the "Sirente crater," Abruzzi, Italy

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Speranza, Fabio; Sagnotti, Leonardo; Rochette, Pierre

2004-04-01

In this paper, we review the recent hypothesis, based mostly on geomorphological features, that a ~130 m-wide sag pond, surrounded by a saddle-shaped rim from the Sirente plain (Abruzzi, Italy), is the first-discovered meteoritic crater of Italy. Sub-circular depressions (hosting ponds), with geomorphological features and size very similar to those exhibited by the main Sirente sag, are exposed in other neighboring intermountain karstic plains from Abruzzi. We have sampled present day soils from these sag ponds and from the Sirente sags (both the main "crater" and some smaller ones, recently interpreted as a crater field) and various Abruzzi paleosols from excavated trenches with an age range encompassing the estimated age of the "Sirente crater." For all samples, we measured the magnetic susceptibility and determined the Ni and Cr contents of selected specimens. The results show that the magnetic susceptibility values and the geochemical composition are similar for all samples (from Sirente and other Abruzzi sags) and are both significantly different from the values reported for soils contaminated by meteoritic dust. No solid evidence pointing at an impact origin exists, besides the circular shape and rim of the main sag. The available observations and data suggest that the "Sirente crater," together with analogous large sags in the Abruzzi intermountain plains, have to be attributed to the historical phenomenon of "transumanza" (seasonal migration of sheep and shepherds), a custom that for centuries characterized the basic social-economical system of the Abruzzi region. Such sags were excavated to provide water for millions of sheep, which spent summers in the Abruzzi karstic high pasture lands, on carbonatic massifs deprived of natural superficial fresh water. Conversely, the distribution of the smaller sags from the Sirente plain correlates with the local pattern of the calcareous bedrock and, together with the characteristics of their internal structure, are

Evidence of the impacting body of the Ries crater - the discovery of Fe-Cr-Ni veinlets below the crater bottom

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El, Goresy A.; Chao, E.C.T.

1976-01-01

Fe-Cr-Ni particles and veinlets have been discovered in the top 15 m of the compressed zone with abundant shatter cones below the bottom of the Ries crater. The metallic particles are less than a few microns across. They occur in various minerals along healed intergranular and locally in intragranular microfractures in quartz diorite, amphibolite and chloritized granite of the basement crystalline rocks. The particles consist of major Fe, Cr, and Ni with minor Si and Ca. Origin due to contamination is absolutely ruled out. We believe that these Fe-Cr-Ni particles are probably condensed from the vaporized impacting body which produced the Ries crater. These particles were injected with high velocity into microfractures near the top of the compressed zone, implanted in and across various minerals before these microfractures were resealed. The presence of Si and Ca as well as the fact that the Cr content is nearly twice that of Ni, led us to conclude that the Ries impacting body is very likely not an iron meteorite but a stony meteorite. ?? 1976.

Educating the Public about Meteorites and Impacts through Virtual Field Trips and Classroom Experience Boxes

Science.gov (United States)

Ashcraft, Teresa; Hines, R.; Minitti, M.; Taylor, W.; Morris, M. A.; Wadhwa, M.

2014-01-01

With specimens representing over 2,000 individual meteorites, the Center for Meteorite Studies (CMS) at Arizona State University (ASU) is home to the world's largest university-based meteorite collection. As part of our mission to provide educational opportunities that expand awareness and understanding of the science of meteoritics, CMS continues to develop new ways to engage the public in meteorite and space science, including the opening of a new Meteorite Gallery, and expansion of online resources through upgrades to the CMS website, meteorites.asu.edu. In 2008, CMS was the recipient of a philanthropic grant to improve online education tools and develop loanable modules for educators. These modules focus on the origin of meteorites, and contain actual meteorite specimens, media resources, a user guide, and lesson plans, as well as a series of engaging activities that utilize hands-on materials geared to help students develop logical thinking, analytical skills, and proficiency in STEM disciplines. In 2010, in partnership with the ASU NASA Astrobiology Institute team, CMS obtained a NASA EPOESS grant to develop Virtual Field Trips (VFTs) complemented by loanable “Experience Boxes” containing lesson plans, media, and hands-on objects related to the VFT sites. One VFT-Box pair focuses on the record of the oldest multicellular organisms on Earth. The second VFT-Box pair focuses on the Upheaval Dome (UD) structure, a meteorite impact crater in Utah’s Canyonlands National Park. UD is widely accepted as the deeply eroded remnant of a ~5 kilometer impact crater (e.g. Kriens et al., 1999). The alternate hypothesis that the Dome was formed by the upwelling of salt from a deposit underlying the region (e.g. Jackson et al., 1998) makes UD an ideal site to learn not only about specific scientific principles present in the Next Generation Science Standards, but also the process of scientific inquiry. The VFTs are located on an interactive website dedicated to VFTs, vft

Experimental impact crater morphology

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Dufresne, A.; Poelchau, M. H.; Hoerth, T.; Schaefer, F.; Thoma, K.; Deutsch, A.; Kenkmann, T.

2012-04-01

The research group MEMIN (Multidisciplinary Experimental and Impact Modelling Research Network) is conducting impact experiments into porous sandstones, examining, among other parameters, the influence of target pore-space saturation with water, and projectile velocity, density and mass, on the cratering process. The high-velocity (2.5-7.8 km/s) impact experiments were carried out at the two-stage light-gas gun facilities of the Fraunhofer Institute EMI (Germany) using steel, iron meteorite (Campo del Cielo IAB), and aluminium projectiles with Seeberg Sandstone as targets. The primary objectives of this study within MEMIN are to provide detailed morphometric data of the experimental craters, and to identify trends and characteristics specific to a given impact parameter. Generally, all craters, regardless of impact conditions, have an inner depression within a highly fragile, white-coloured centre, an outer spallation (i.e. tensile failure) zone, and areas of arrested spallation (i.e. spall fragments that were not completely dislodged from the target) at the crater rim. Within this general morphological framework, distinct trends and differences in crater dimensions and morphological characteristics are identified. With increasing impact velocity, the volume of craters in dry targets increases by a factor of ~4 when doubling velocity. At identical impact conditions (steel projectiles, ~5km/s), craters in dry and wet sandstone targets differ significantly in that "wet" craters are up to 76% larger in volume, have depth-diameter ratios generally below 0.19 (whereas dry craters are almost consistently above this value) at significantly larger diameters, and their spallation zone morphologies show very different characteristics. In dry craters, the spall zone surfaces dip evenly at 10-20° towards the crater centre. In wet craters, on the other hand, they consist of slightly convex slopes of 10-35° adjacent to the inner depression, and of sub-horizontal tensile

The Wells Creek Meteorite Impact Site and Changing Views on Impact Cratering

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Ford, J. R. H.; Orchiston, Wayne; Clendening, Ron

2012-11-01

Wells Creek is a confirmed meteorite impact site in Tennessee, USA. The Wells Creek structure was first noticed by railroad surveyors around 1855 and brought to the attention of J.M. Safford, Tennessee's State Geologist. He included an insert in the 1869 Geologic Map of Tennessee, which is the first known map to include the structure. The origin of the Wells Creek structure was controversial, and was interpreted as being either the result of volcanic steam explosion or meteorite impact. It was only in the 1960s that Wilson and Stearns were able to state that the impact hypothesis was preferred. Evidence for a Wells Creek meteorite impact includes drill core results, extreme brecciation and shatter cones, while a local lack of volcanic material is telling. Just to the north of the Wells Creek Basin are three small basins that Wilson concluded were associated with the Wells Creek impact event, but evidence regarding the origin of the Austin, Indian Mound and Cave Spring Hollow sites is not conclusive.

Zhamanshin and Aouelloul - Craters produced by impact of tektite-like glasses?

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O'Keefe, John A.

1987-01-01

It is shown that the enhanced abundance of siderophile elements and chromium in tektite-like glasses from the two impact craters of Zhamanshin and Aouelloul cannot be explained as a result of contamination of the country rock by meteorites nor, probably, comets. The pattern is, however, like that found in certain Australasian tektites, and in Ivory Coast tektites. It is concluded, in agreement with earlier suggestions by Campbell-Smith and Hey, that these craters were formed by the impact of large masses of tektite-like glass, of which the glasses which were studied are fragments. It follows that it is necessary, in considering an impact crater, to bear in mind that the projectile may have been a glass.

Geochemistry of Lunar Highland Meteorites Mil, 090034, 090036 AND 090070

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Shirai, N.aoki; Ebihara, M.; Sekimoto, S.; Yamaguchi, A.; Nyquist, L.; Shih, C.-Y.; Park, J.; Nagao, K.

2012-01-01

Apollo and Luna samples were collected from a restricted area on the near side of the Moon, while the source craters of the lunar meteorites are randomly distributed. For example, Takeda et al. [1] and Yamaguchi et al. [2] found a variety of lithic clasts in Dho 489 and Y 86032 which were not represented by Apollo samples, and some of these clasts have lower rare earth elements (REE) and FeO abundances than Apollo anorthosites, respectively. Takeda et al. [1] and Yamaguchi et al. [2] concluded that Dho 489 and Y 86032 originated from the lunar farside. Therefore, lunar meteorites provide an opportunity to study lunar surface rocks from areas not sampled by Apollo and Luna missions. Three lunar anorthitic breccias (MIL 090034, 090036 and 090070) were found on the Miller Range Ice Field in Antarctica during the 2009-2010 ANSMET season [3]. In this study, we determined elemental abudnances for MIL 090034, 090036 and 090070 by using INAA and aimed to characterize these meteorites in chemical compositions in comparison with those for other lunar meteorites and Apollo samples.

Noble Gases in the Lunar Meteorites Calcalong Creek and QUE 93069

Science.gov (United States)

Swindle, T. D.; Burkland, M. K.; Grier, J. A.

1995-09-01

Although the world's collections contain comparable numbers of martian and lunar meteorites (about 10 each), their ejection histories seem to be quite different [1]. We have sampled no more than four martian craters, but almost every one of the lunar meteorites apparently represents a separate cratering event. Furthermore, most lunar meteorites were apparently ejected from the top meter of the surface, unlike any of the martian meteorites. We have measured noble gases in two bulk samples of the lunar meteorite QUE93069 and three of Calcalong Creek, ranging in size from 7 to 15 mg. Averaged results are given in Table 1. Both meteorites contain solar-wind-implanted noble gas. QUE 93069, which is a mature anorthositic regolith breccia [2], contains amounts comparable to the most gas-rich lunar meteorites. The relatively low 40Ar/36Ar ratios of both meteorites suggest surface exposures no more than 2.5 Ga ago [3]. Calcalong Creek has readily observable spallogenic gas. The 131Xe/126Xe ratio of 4.8+/-0.3 corresponds to an average shielding depth of slightly more than 40 gm/cm^2 [4]. In common with many lunar breccias, Calcalong Creek has been exposed to cosmic rays for several hundred Ma (calculations based on [4] and [5]). The 3He apparent exposure age is much shorter, suggesting diffusive loss of He. To determine the detailed exposure history, it is necessary to have measurements of cosmogenic radionuclides. Our samples were too small to measure 81Kr, but [6] have measured 10Be, 26Al and 36Cl. Their data are consistent with either extended exposure at data, requiring several hundred Ma of exposure at an average depth of 40-50 gm/cm^2, are clearly more consistent with the first scenario. The only other lunar meteorite which could have been ejected at the same time is MAC 88104/5 [1], but the chemical differences between the two make it highly unlikely that they come from the same event. It is difficult to determine the amount of spallogenic gas in QUE 93069 because of

Evidence for a meteoritic origin of the September 15, 2007, Carancas crater

OpenAIRE

Le Pichon, A.; Antier, K.; Cansi, Y.; Hernandez, B.; Minaya, E.; Burgoa, B.; Drob, D.; Evers, L. G.; Vaubaillon, J.

2008-01-01

On September 15th, 2007, around 11:45 local time in Peru, near the Bolivian border, the atmospheric entry of a meteoroid produced bright lights in the sky and intense detonations. Soon after, a crater was discovered south of Lake Titicaca. These events have been detected by the Bolivian seismic network and two infrasound arrays operating for the Comprehensive Nuclear-Test-Ban Treaty Organization, situated at about 80 and 1620 km from the crater. The localization and origin time ...

Hailar crater - A possible impact structure in Inner Mongolia, China

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Xiao, Zhiyong; Chen, Zhaoxu; Pu, Jiang; Xiao, Xiao; Wang, Yichen; Huang, Jun

2018-04-01

Hailar crater, a probable impact structure, is a circular depression about 300 m diameter in Inner Mongolia, northeast China. With broad elevated rims, the present rim-to-floor depth is 8-20 m. Regional geological background and geomorphological comparison suggest that this feature is likely not formed by surface processes such as salt diapir, karst, aeolian, glacial, or volcanic activity. Its unique occurrence in this region and well-preserved morphology are most consistent with it being a Cenozoic impact crater. Two field expeditions in 2016 and 2017 investigated the origin of this structure, recognizing that (1) no additional craters were identified around Hailar crater in the centimeter-scale digital topography models that were constructed using a drone imaging system and stereo photogrammetry; (2) no bedrock exposures are visible within or adjacent to the crater because of thick regolith coverage, and only small pieces of angular unconsolidated rocks are present on the crater wall and the gently-sloped crater rim, suggesting recent energetic formation of the crater; (3) most samples collected from the crater have identical lithology and petrographic characteristics with the background terrain, but some crater samples contain more abundant clasts and silicate hydrothermal veins, indicating that rocks from depths have been exposed by the crater; (4) no shock metamorphic features were found in the samples after thin section examinations; and (5) a systematic sample survey and iron detector scan within and outside of the crater found no iron-rich meteorites larger than 2 cm in size in a depth of 30 cm. Although no conclusive evidence for an impact origin is found yet, Hailar crater was most likely formed by an impact based on its unique occurrence and comparative geomorphologic study. We suggest that drilling in the crater center is required to verify the impact origin, where hypothesized melt-bearing impactites may be encountered.

Oblique impact: a process for providing meteorite samples of other planets

International Nuclear Information System (INIS)

Okeefe, J.D.; Ahrens, T.J.

1986-03-01

Cratering flow calculations for a series of oblique to normal impacts of silicate projectiles onto a silicate halfspace were carried out to determine whether the gas produced upon shock vaporizing both projectile and planetary material could entrain and accelerate surface rocks and thus provide a mechanism for propelling SNC meteorites from the Martian surface. The difficult constraints that the impact origin hypothesis for SNC meteorites has to satisfy are that these meteorites are lightly to moderately shocked and yet were accelerated to speeds in excess of the Martian escape velocity. Two dimensional finite difference calculations demonstrate that at highly probable impact velocities, vapor plume jets are produced at oblique impact angles of 25 deg to 60 deg and have speeds as great as 20 km/sec. These plumes flow nearly parallel to the planetary surface. It is shown that upon impact of projectiles having radii of 0.1 to 1 km, the resulting vapor jets have densities of 0.1 to 1 g/cu.cm. These jets can entrain Martian surface rocks and accelerate them to velocities 5 km/sec. It is suggested that this mechanism launches SNC meteorites to Earth

Mineralogical characterization of a meteorite impact in Carancas, Puno

International Nuclear Information System (INIS)

Ceron Loayza, Maria L.; Bravo Cabrejos, Jorge A.

2009-01-01

We report the results of the study of a meteorite that impacted an inhabited zone in the neighborhood of the town of Carancas, Puno Region, about 1,300 km south of Lima. The analysis carried out by X ray diffractometry, transmission Moessbauer spectroscopy (at room temperature and at 4,2 K), and by energy dispersive X ray fluorescence reveal the presence in the meteorite simple of magnetic sites assigned to the Fe-Ni and troilite (Fe,S) phases, and of 3 paramagnetic doublets, two of them assigned to Fe 2+ , one associated to olivine and the other to pyroxene, and the third one due to a site occupied by Fe 3+ , which can be associated to oxides in a superparamagnetic state and/or by an Fe hydroxide. The soil samples from the crater reveal a composition that consists mainly of quartz, albite and impactites such as coesite and stishovite (SiO 2 ). The occurrence of these phases with a high content of SiO 2 in the crater soils strengthens the hypothesis of their origin induced by impact; we observe also the presence of the Fe oxide hematite, of aluminum silicates such as illite and montmorillonite, and an unassigned phase of Fe 3+ . In general, the results obtained by these techniques complement each other rather well and allow the verification of the origin of the studied simples. (author).

Diversity of Rock Compositions at Gale Crater Observed by ChemCam and APXS on Curiosity, and Comparison to Meteorite and Orbital Observations

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Wiens, R. C.; Maurice, S.; Grotzinger, J. P.; Gellert, R.; Mangold, N.; Sautter, V.; Ollila, A.; Dyar, M. D.; Le Mouelic, S.; Ehlmann, B. L.; Clegg, S. M.; Lanza, N.; Cousin, A.; Forni, O.; Gasnault, O.; Lasue, J.; Blaney, D. L.; Newsom, H. E.; Herkenhoff, K. E.; Anderson, R. B.; D'Uston, L.; Bridges, N. T.; Fabre, C.; Meslin, P.; Johnson, J.; Vaniman, D.; Bridges, J.; Dromart, G.; Schmidt, M. E.; Team, M.

2013-12-01

Gale crater was selected as the Curiosity landing site because of the apparent sedimentary spectral signatures seen from orbit. Sedimentary materials on Mars have to this point showed very little expression of major element mobility, so compositions of precursor igneous minerals play a strong role in the compositions of sediments. In addition, pebbles and float rocks on Bradbury Rise (sols 0-50, > 324) appear to be mostly igneous in origin, and are assumed to have been carried down from the crater rim. Overall in the first year on Mars ChemCam obtained >75,000 LIBS spectra on > 2,000 observation points, supported by > 1,000 RMI images, and APXS obtained a significant number of observations. These show surprisingly variable compositions. The mean ChemCam compositions for Bradbury Rise dust-free rocks and pebbles (62 locations) give SiO2 = 56%, FeOT = 16% and show high alkalis consistent with Jake Matijevic (sol ~47) APXS Na2O ~6.6 wt%. ChemCam observations on the conglomerate Link (sol 27) gave Rb > 150 ppm and Sr > 1500 ppm. These compositions imply the presence of abundant alkali feldspars in the material infilling the lower parts of Gale crater. They are generally consistent with the more feldspar-rich SNC meteorites but show a radical departure from larger scale orbital observations, e.g., GRS, raising the question of how widespread these compositions are outside of Gale crater. Sedimentary materials at Yellowknife Bay encompassing the Sheepbed (sols 125-300) and Shaler (sols 121, 311-324) units, potentially including Point Lake (sols 301-310) and Rocknest (sols 57-97), appear to have incorporated varying amounts of igneous source materials. Seven rocks investigated at Rocknest show significant additions of Fe, with mean FeOT = 25% (154 locations), suggesting that FeO was a cementing agent. ChemCam observations at Shaler show varying amounts of alkali feldspar (i.e., related to Bradbury Rise), Fe-rich material (Rocknest-like), and potassium-rich material

Delivery of asteroids and meteorites to the inner solar system

International Nuclear Information System (INIS)

Greenberg, R.; Nolan, M.C.

1989-01-01

This paper discusses how critical observational constraints on the delivery of asteroids (including the very small ones, called meteorites, that land on the Earth) include orbital distributions, exposure ages and mineralogy. Orbital maturity in the inner solar system is indicated by the AM/PM distribution of meteorite falls and fireballs: orbits with perihelia at 1 AU are less mature and arrive preferentially in the PM. Ordinary chondrites have short exposure ages, but their AM/PM fall statistics indicate significant orbital maturity. Hence, many may be collisional offspring of slightly larger parents that emigrated from the main belt. The required size distribution, extrapolated up to multi-km-size bodies, would also yield numbers of planet-crossing asteroids comparable to those astronomically observed. However, such a distribution requires launch on Earth-bound trajectories by catastrophic disruption events, which probably cannot launch sufficient material at high enough velocities Cratering events offer higher ejecta velocities, and if dominant would explain the abundance of basaltic meteorites relative to olivine, which should constitute the bulk of a differentiated parent body's volume

The fourth Arab Impact Cratering and Astrogeology Conference (AICAC IV), April 9-12, 2017, Algiers (Algeria)

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Belhaï, D.; Chennaoui-Aoudjehane, H.; Baratoux, D.; Ferrière, L.; Lamali, A.; Sahoui, R.; Lambert, P.; Ayadi, A.

2017-09-01

We present a report about the fourth Arab Impact Cratering and Astrogeology Conference (AICAC IV) that took place in Algiers at the USTHB (Université des Sciences et Technologie Houari Boumedienne, Algiers, Algeria) in the presence of the presidents of the USTHB and Boumerdès Universities, the Director of CRAAG (Centre de Recherche en Astronomie, Astrophysique et Géophysique), and the General Director of the National Administration for Scientific Research (NASR/DGRSDT). This series of conferences aims to promote research interest for impact cratering in the Arab world and beyond, including for instance in African countries. In spite of persistently restraining travel measures to Algeria, the fourth edition held in Algiers was marked by continuous international participation, with participants from seven different countries. This conference focused on presentations of scientific results in the research fields related to planetology, meteorites, and impact craters. In particular, the Algerian impact structures were under the spotlights during both oral and poster sessions. During this conference, the presence of freshly graduated Ph.D. students and new Ph.D. projects related to impact cratering or meteoritic science was a positive sign for the consolidation of research groups in this domain in the Arab world and Africa. Therefore, international cooperation or external support and funding are still needed to ensure the development of this scientific discipline in this part of the world.

Cratering record in the inner solar system: Implications for earth

International Nuclear Information System (INIS)

Barlow, N.G.

1988-01-01

Internal and external processes have reworked the Earth's surface throughout its history. In particular, the effect of meteorite impacts on the early history of the earth is lost due to fluvial, aeolian, volcanic and plate tectonic action. The cratering record on other inner solar system bodies often provides the only clue to the relative cratering rates and intensities that the earth has experienced throughout its history. Of the five major bodies within the inner solar system, Mercury, Mars, and the Moon retain scars of an early episode of high impact rates. The heavily cratered regions on Mercury, Mars, and the Moon show crater size-frequency distribution curves similar in shape and crater density, whereas the lightly cratered plains on the Moon and Mars show distribution curves which, although similar to each other, are statistically different in shape and density from the more heavily cratered units. The similarities among crater size-frequency distribution curves for the Moon, Mercury, and Mars suggest that the entire inner solar system was subjected to the two populations of impacting objects but Earth and Venus have lost their record of heavy bombardment impactors. Thus, based on the cratering record on the Moon, Mercury, and Mars, it can be inferred that the Earth experienced a period of high crater rates and basin formation prior to about 3.8 BY ago. Recent studies have linked mass extinctions to large terrestrial impacts, so life forms were unable to establish themselves until impact rates decreased substantially and terrestrial conditions became more benign. The possible periodicity of mass extinctions has led to the theory of fluctuating impact rates due to comet showers in the post heavy bombardment period. The active erosional environment on the Earth complicates attempts to verify these showers by erasing geological evidence of older impact craters

Preliminary results of soil radon gas survey of the Lake Bosomtwi impact crater

International Nuclear Information System (INIS)

Preko, S.; Danuor, S.K.; Menyeh, A.

2004-01-01

Soil radon gas survey was carried out in the Lake Bosomtwi impact crater area on eight profiles, which ran rapidly toward the end of the crater. One thousand soil samples, each weighing about 100g were acquired at a depth of 20 cm and at regular intervals of 10 m. The radon gas decay rate of the soil samples was then determined in the laboratory using the RDA-200 Radon detector and RDU-200 Degassing unit. It was found that generally areas south and east of the crater, which are severally sheared, faulted and fractured recorded high radon gas decay rates of the order of 800 counts/min whilst relatively undisturbed zones west of the crater recorded lower rates of the order of 20 counts/min. the cause of fracturing, shearing and faulting have been attributed to the effect of the meteorite impact in the Bosomtwi area, and therefore the results indicate that the soil radon gas survey could serve as a useful tool in mapping the impact-related structural characteristics of the crater. (author)

Hypothetical source crater for Australasian tektites: Moving from Indochina to Northwest China?

Czech Academy of Sciences Publication Activity Database

Mizera, Jiří; Řanda, Zdeněk; Kameník, Jan; Klokočník, Jaroslav; Kostelecký, J.

2016-01-01

Roč. 51, AUG (2016), A467-A467 ISSN 1086-9379. [79th Annual Meeting of the Meteoritical-Society. 07.08.2016-12.08.2016, Berlin] R&D Projects: GA ČR GA13-22351S; GA MŠk LM2015056 Institutional support: RVO:61389005 ; RVO:67985815 Keywords : ATT * Indochina * crater Subject RIV: DD - Geochemistry; BN - Astronomy, Celestial Mechanics, Astrophysics (ASU-R)

The Orgueil meteorite: 150 years of history

Science.gov (United States)

Gounelle, Matthieu; Zolensky, Michael E.

2014-10-01

The goal of this paper is to summarize 150 yr of history of a very special meteorite. The Orgueil meteorite fell near Montauban in southwestern France on May 14, 1864. The bolide, which was the size of the full Moon, was seen across Western France, and almost immediately made the news in local and Parisian newspapers. Within a few weeks of the fall, a great diversity of analyses were performed under the authority of Gabriel Auguste Daubrée, geology professor at the Paris Museum, and published in the Comptes Rendus de l'Académie des Sciences. The skilled scientists reported the presence of iron sulfides, hydrated silicates, and carbonates in Orgueil. They also characterized ammonium salts which are now gone, and observed sulfates being remobilized at the surface of the stone. They identified the high water and carbon contents, and noted similarities with the Alais meteorite, which had fallen in 1806, 300 km away. While Daubrée and his colleagues noted the similarity of the Orgueil organic matter with some terrestrial humus, they were cautious not to make a direct link with living organisms. One century later, Nagy and Claus were less prudent and announced the discovery of "organized" elements in some samples of Orgueil. Their observations were quickly discredited by Edward Anders and others who also discovered that some pollen grains were intentionally placed into the rock back in the 1860s. Orgueil is now one of the most studied meteorites, indeed one of the most studied rocks of any kind. Not only does it contain a large diversity of carbon-rich compounds, which help address the question of organo-synthesis in the early solar system but its chemical composition is also close to that of the Sun's photosphere and serves as a cosmic reference. Secondary minerals, which make up 99% of the volume of Orgueil, were probably formed during hydrothermal alteration on the parent-body within the first few million years of the solar system; their study is essential to our

Dynamics of crater formations in immersed granular materials

Science.gov (United States)

Varas, G.; Vidal, V.; Géminard, J.

2009-12-01

Craters are part of the widespread phenomena observed in nature. Among the main applications to natural phenomena, aside from meteorite impact craters, are the formation and growth of volcanic edifices, by successive ejecta emplacement and/or erosion. The time evolution and dynamics play a crucial role here, as the competition between volcanic-jet mass-flux (degassing and ejecta) and crater-size evolution may control directly the eruptive regime. Crater morphology in dry granular material has been extensively studied, both experimentally and theoretically. Most of these studies investigate the final, steady crater shape resulting from the collision of solid bodies with the material surface and scaling laws are derived. In immersed granular material, craters generated by an underwater vortex ring, or underwater impact craters generated by landslide, have been reported. In a previous experimental study, Gostiaux et al. [Gran. Matt., 2002] have investigated the dynamics of air flowing through an immersed granular layer. They reported that, depending on the flow rate, the system exhibits two qualitatively different regimes: At small flow rate, the bubbling regime during which bubbles escape the granular layer independently one from another; At large flow rate, the open-channel regime which corresponds to the formation of a channel crossing the whole thickness of the granular bed through which air escapes almost continuously. At intermediate flow rate, a spontaneous alternation between these two regimes is observed. Here, we report the dynamics of crater formations at the free surface of an immersed granular bed, locally crossed by an ascending gas flow. We reproduce the experimental conditions of Gostiaux et al. (2002) in two dimensions: In a vertical Hele-Shaw cell, the crater consists of two sand piles which develop around the location of the gas emission. We observe that the typical size of the crater increases logarithmically with time, independently of the gas

Thirteen Iron Meteorites Found at Gale Crater, Meridiani Planum, and Gusev Crater — Exogenic Witnesses to Weathering Processes Near the Martian Equator

Science.gov (United States)

Ashley, J.

2014-12-01

At least 20 meteorites and meteorite candidates have now been found by science teams at three Mars rover landing sites, all within 15 degrees of the martian equator. Thirteen of these are iron meteorites, comprising 65% of the population — an order of magnitude greater abundance than found among witnessed iron falls in Earth-based collections (~6%). Chondritic meteorites, which comprise some 86% of Earth-based falls, are conspicuously absent from the Mars inventory. The reasons for this disproportion may involve a) post-fall environmental resistance differences favoring iron survivability; b) fragmentation from impact shock (and possibly internal weathering stresses associated with oxide production in desert environments [1]); combined with c) selection biases arising from residual chondritic fragments appearing less conspicuous. Impact features along rover traverses often show evidence of dark materials likely to be impactor fragments [e.g., 2], which could represent the missing chondritic fraction. The reactivity of reduced (metallic) iron to aqueous alteration, combined with the near equatorial and widely distributed locations of these rocks, makes them particularly useful to the assessment of climate models arguing for geologically recent ice at the martian equator. Exposure histories involving alternating wind/water cycles are imprinted on several Meridiani irons, for example [3]. Evidence for oxide coating removal demonstrates the current epoch to be one of coating destruction, not production, showing that atmospheric exposure alone is insufficient to produce the coating. Cavernous weathering is likely associated with acidic corrosion, while evidence of aeolian scouring is found in Widmanstätten patterns, sharp-crested scallops, regmaglypt enlargement, and abundant pitting. Further study of these features could help constrain wind direction and velocity during epochs of sculpting [e.g., 4], and assist in exposure age estimation. References: [1] Ashley J. W

Supply of the numerical simulation for the evaluation of the sonic boom of meteorites

International Nuclear Information System (INIS)

Henneton, Martin

2013-01-01

Within the framework of the Comprehensive Nuclear-Test-Ban Treaty, infra-sound is one survey technique monitoring nuclear explosions. These ones have to be distinguished from natural sources of infra-sound like atmospheric meteorite entries. With a view to investigate meteorites as an infra-sound source, finite volume simulations of the hypersonic flow are performed at sufficiently far distances to reach the acoustic regime. They are then matched to a nonlinear ray tracing method to propagate the signal within the atmosphere down to the ground. For perfect gases, this approach allows us to validate the theoretical model based on simplifying assumptions. More realistic simulations in real gases at thermochemical equilibrium, show a major modification of the pressure field in the near field but a moderate influence for infra-sound at the ground level. Numerical results are compared to infra-sound and seismic measurements in the case of the well-documented meteorite of Carancas (Peru, 2007). This confrontation highlights a good agreement for the spectrum of the waveform but a large overestimation of the overpressure at receptors located near the impact crater. This study also allowed us to propose a new entry trajectory for the meteorite, and to identify one of the recorded signals as a sonic boom. (author) [fr

AMS radiocarbon dating of lacustrine sediment from an impact crater in northeastern China

Energy Technology Data Exchange (ETDEWEB)

Liu, K.X. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Chen, M., E-mail: mchen@gig.ac.cn [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Ding, X.F.; Fu, D.P. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Ding, P. [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Shen, C.D., E-mail: cdshen@gig.ac.cn [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Xiao, W.S. [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China)

2013-01-15

In order to investigate the origin and age of a bowl-shaped crater with 1.8 km diameter in northeastern China, a core drilling about 110 m in total was carried out in 2009 at the center of the crater. A 106-m-thick unit of lacustrine sediment is revealed under a surface layer of about 1 m of yellow soil. The impact origin has been confirmed based on geological analysis. In this paper, we report the AMS {sup 14}C dating results of lacustrine sediment. The data suggest that the meteorite impact in Xiuyan happened more than 50,000 years ago and a two-section linear relationship of {sup 14}C ages with the depth shows a stable sediment environment through the two time stages.

Heavy Cratering near Callisto's South Pole

Science.gov (United States)

1997-01-01

Images from NASA's Galileo spacecraft provide new insights into this region near Callisto's south pole. This two frame mosaic shows a heavily cratered surface with smooth plains in the areas between craters. North is to the top of the image. The smoothness of the plains appears to increase toward the south pole, approximately 480 kilometers (293 miles) south of the bottom of the image. This smoothness of Callisto's surface was not evident in images taken during the 1979 flyby of NASA's Voyager spacecraft because the resolution was insufficient to show the effect. This smooth surface, and the process(es) that cause it, are among the most intriguing aspects of Callisto. Although not fully understood, the process(es) responsible for this smoothing could include erosion by tiny meteorites and energetic ions. Some craters, such as Keelut, the 47 kilometer (29 mile) crater in the lower right corner, have sharp, well defined rims. Keelut contains an inner ring surrounding a central depression about 17 kilometers (11 miles) in diameter. Keelut, and the more irregularly shaped, degraded Reginleif, the 32 kilometer (19.5 mile) crater in the top center of the image, are very shallow and have flat floors. Crater forms can be seen down to less than 2 kilometers (1.2 miles) in diameter in the image. Each picture element (pixel) in this image is approximately 0.68 kilometers (0.41 miles) across.This image which was taken by the Galileo spacecraft's solid state imaging (CCD) system during its eighth orbit around Jupiter, on May 6th, 1997. The center of the image is located at 71.3 degrees south latitude, 97.6 degrees west longitude, and was taken when the spacecraft was approximately 35,470 kilometers (21,637 miles) from Callisto.The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http

Principles of meteoritics

CERN Document Server

Krinov, E L

1960-01-01

Principles of Meteoritics examines the significance of meteorites in relation to cosmogony and to the origin of the planetary system. The book discusses the science of meteoritics and the sources of meteorites. Scientists study the morphology of meteorites to determine their motion in the atmosphere. The scope of such study includes all forms of meteorites, the circumstances of their fall to earth, their motion in the atmosphere, and their orbits in space. Meteoric bodies vary in sizes; in calculating their motion in interplanetary space, astronomers apply the laws of Kepler. In the region of

Meteorites for K-12 Classrooms: NASA Meteorite Educational Materials

Science.gov (United States)

Lindstrom, M.; Allen, J.

1995-09-01

The fall of a new meteorite is an event that catches the interest of the public in matters of science. The threat of a huge impact like last year's comet Shoemaker-Levy 9 gives us all reason to evaluate such potential risks. NASA's meteorite educational materials use our natural interest in rocks from space to present classroom activities on planetary science. The meteorite educational package includes a meteorite sample disk, a teachers's guide and a slide set. The sample disk is a lucite disk containing chips of six different kinds of meteorites (3 chondrites, achondrite, iron, stony-iron). EXPLORING METEORITE MYSTERIES is a teacher's guide with background information and 19 hands-on or heads-on activities for grades 4-12. It was prepared in a partnership of planetary scientists and teachers. The slide set consists of 48 slides with captions to be used with the activities. The materials will be available in Fall 1995. Teachers may obtain a loan of the whole package from NASA Teacher Resource Centers; researchers may borrow them from the JSC meteorite curator. The booklet is available separately from the same sources, and the slide set will be available from NASA CORE. EXPLORING METEORITE MYSTERIES is an interdisciplinary planetary science unit which teaches basic science concepts and techniques together with math, reading, writing and social studies The activities are done in a variety of different teaching styles which emphasize observation, experimentation and critical thinking. The activities are ideal for middle schools where teaming makes interdisciplinary units desireable, but most of the activities can be easily modified for grade levels from upper elementary through high school. Meteorites are a natural subject for interdisciplinary teaching because their study involves all fields of science and offers fascinating historical accounts and possibilities for creative expression. Topics covered in EXPLORING METEORITE MYSTERES are centered around basic

Kosice meteorite analysis

International Nuclear Information System (INIS)

Sitek, J.; Degmova, J.; Dekan, J.

2011-01-01

Meteorite Kosice fell down 28 th of February 2010 near the Kosice and represents an unique find, because the last fall of meteorite was observed in Slovakia at the year 1895. It supposes that for this kind of meteorite the orbit in cosmic space could be calculated. This is one of most important part because until now 13 places of meteorite find are known in the world of which cosmic orbit in space have been calculated. Slovakia is member of international bolide net, dealing with meteorite analysis in Middle Europe .Analysis of Kosice meteorite will also concern at the long live and short live nuclides. Results should be a contribution to determination of radiation and formative ages. From structural analysis of meteorite it will be possible to compare it with similar types of meteorites. In this work Moessbauer spectroscopy will be used for phase analysis from point of view iron contain components with the aim to identify magnetic and non magnetic fractions. From the analysis of magnetic part we can find that the first sextet with hyperfine magnetic field 33.5 T corresponds to bcc Fe-Ni alloy (kamacite) and second with field 31.5 T to FeS (triolite). Meteorites with mentioned composition belong to the mineral group of chondrites. Comparing our parameters with results of measurements at the similar meteorites we can conclude that Kosice meteorite contains the same components. According all Moessbauer parameters we can also include this meteorite in the mineral group of chondrites. (authors)

Fresh Impact Crater and Rays in Tharsis

Science.gov (United States)

2002-01-01

The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission has included dozens of opportunities to point the spacecraft directly at features of interest so that pictures of things not seen during the earlier Mapping Mission can be obtained. The example shown here is a small meteorite impact crater in northern Tharsis near 17.2oN, 113.8oW. Viking Orbiter images from the late 1970's showed at this location what appeared to be a dark patch with dark rays emanating from a brighter center. The MOC team surmised that the dark rays may be indicating the location of afresh crater formed by impact sometime in the past few centuries (since dark ray are quickly covered by dust falling out of the martian atmosphere). All through MOC's Mapping Mission in 1999 and 2000, attempts were made to image the crater as predictions indicated that the spacecraft would pass over the site, but the crater was never seen. Finally, in June 2001, Extended Mission operations allowed the MOC team to point the spacecraft (and hence the camera, which is fixed to the spacecraft)directly at the center of the dark rays, where we expected to find the crater.The picture on the left (above, A) is a mosaic of three MOC high resolution images and one much lower-resolution Viking image. From left to right, the images used in the mosaic are: Viking 1 516A55, MOC E05-01904, MOCM21-00272, and MOC M08-03697. Image E05-01904 is the one taken in June 2001 by pointing the spacecraft. It captured the impact crater responsible for the rays. A close-up of the crater, which is only 130 meters (427 ft)across, is shown on the right (above, B). This crater is only one-tenth the size of the famous Meteor Crater in northern Arizona.The June 2001 MOC image reveals many surprises about this feature. For one, the crater is not located at the center of the bright area from which the dark rays radiate. The rays point to the center of this bright area, not the crater. Further, the dark material ejected from the

Exploration of microbial diversity and community structure of Lonar Lake: the only hypersaline meteorite crater lake within basalt rock

Directory of Open Access Journals (Sweden)

Dhiraj ePaul

2016-01-01

Full Text Available Lonar Lake is a hypersaline and hyperalkaline soda lake and the only meteorite impact crater in the world created in the basalt rocks. Although culture-dependent studies have been reported, the comprehensive understanding of microbial community composition and structure of Lonar Lake remain obscure. In the present study, microbial community structure associated with Lonar Lake sediment and water samples was investigated using high throughput sequencing. Microbial diversity analysis revealed the existence of diverse, yet near consistent community composition. The predominance of bacterial phyla Proteobacteria (30% followed by Actinobacteria (24%, Firmicutes (11% and Cyanobacteria (5% was observed. Bacterial phylum Bacteroidetes (1.12%, BD1-5 (0.5%, Nitrospirae (0.41% and Verrucomicrobia (0.28% were detected as relatively minor populations in Lonar Lake ecosystem. Within Proteobacteria, Gammaproteobacteria represented the most abundant population (21-47% among all the sediments and as a minor population in water samples. Bacterial members Proteobacteria and Firmicutes were present significantly higher (p≥0.05 in sediment samples, whereas members of Actinobacteria, Candidate_division_TM7 and Cyanobacteria (p≥0.05 were significantly abundant in water samples. It was noted that compared to other hypersaline soda lakes, Lonar Lake samples formed one distinct cluster, suggesting a different microbial community composition and structure. The present study reports for the first time the different composition of indigenous microbial communities between the sediment and water samples of Lonar Lake. Having better insight of community structure of this Lake ecosystem could be useful in understanding the microbial role in the geochemical cycle for future functional exploration of the unique hypersaline Lonar Lake.

Meteorite impact craters and possibly impact-related structures in Estonia

Science.gov (United States)

Plado, Jüri

2012-10-01

Three structures (Neugrund, Kärdla, and Kaali) of proven impact origin make Estonia the most cratered country in the world by area. In addition, several candidate impact structures exist, waiting for future studies to determine their origin. This article is an overview of these proven and possible impact structures, including some breccia layers. It summarizes the information and descriptions of the morphology; geological characteristics; and mineralogical, chemical, and geophysical data available in the literature. The overview was prepared to make information in many earlier publications in local journals (many of which had been published in Estonian or Russian) accessible to the international community. This review summarizes the facts and observations in a historical fashion, summarizing the current state of knowledge with some additional comments, and providing the references.

Delineating Bukit Bunuh impact crater boundary by geophysical and geotechnical investigation

Energy Technology Data Exchange (ETDEWEB)

Azwin, I. N., E-mail: nurazwinismail@yahoo.com; Rosli, S.; Nordiana, M. M.; Ragu, R. R.; Mark, J. [Geophysics Section, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Mokhtar, S. [Centre for Global Archaeological Research Malaysia, 11800 USM, Penang (Malaysia)

2015-03-30

Evidences of crater morphology and shock metamorphism in Bukit Bunuh, Lenggong, Malaysia were found during the archaeological research conducted by the Centre for Global Archaeological Research Malaysia, Universiti Sains Malaysia. In order to register Bukit Bunuh as one of the world meteorite impact site, detailed studies are needed to verify the boundary of the crater accordingly. Geophysical study was conducted utilising the seismic refraction and 2-D electrical resistivity method. Seismic refraction survey was done using ABEM MK8 24 channel seismograph with 14Hz geophones and 40kg weight drop while 2-D electrical resistivity survey was performed using ABEM SAS4000 Terrameter and ES10-64C electrode selector with pole-dipole array. Bedrock depths were digitized from the sections obtained. The produced bedrock topography map shows that there is low bedrock level circulated by high elevated bedrock and interpreted as crater and rim respectively with diameter approximately 8km. There are also few spots of high elevated bedrock appear at the centre of the crater which interpreted as rebounds zone. Generally, the research area is divided into two layers where the first layer with velocity 400-1100 m/s and resistivity value of 10-800 Om predominantly consists of alluvium mix with gravel and boulders. Second layer represents granitic bedrock with depth of 5-50m having velocity >2100 m/s and resistivity value of >1500 Om. This research is strengthen by good correlation between geophysical data and geotechnical borehole records executed inside and outside of the crater, on the rim, as well as at the rebound area.

Mineral-produced high-pressure striae and clay polish: Key evidence for nonballistic transport of ejecta from Ries crater

Science.gov (United States)

Chao, E.C.T.

1976-01-01

Recently discovered mineral-produced, deeply incised striae and mirror-like polish on broken surfaces of limestone fragments from the sedimentary ejecta of the Ries impact crater of southern Germany are described. The striae and polish were produced under high confining pressures during high-velocity nonballistic transport of the ejecta mass within the time span of the cratering event (measured in terms of seconds). The striae on these fragments were produced by scouring by small mineral grains embedded in the surrounding clay matrix, and the polish was formed under the same condition, by movements of relatively fragment-free clay against the fragment surfaces. The occurrence of these striae and polish is key evidence for estimating the distribution and determining the relative importance of nonballistic and ballistic transport of ejecta from the shallow Ries stony meteorite impact crater.

Large sulfur isotope fractionations in Martian sediments at Gale crater

Science.gov (United States)

Franz, H. B.; McAdam, A. C.; Ming, D. W.; Freissinet, C.; Mahaffy, P. R.; Eldridge, D. L.; Fischer, W. W.; Grotzinger, J. P.; House, C. H.; Hurowitz, J. A.; McLennan, S. M.; Schwenzer, S. P.; Vaniman, D. T.; Archer, P. D., Jr.; Atreya, S. K.; Conrad, P. G.; Dottin, J. W., III; Eigenbrode, J. L.; Farley, K. A.; Glavin, D. P.; Johnson, S. S.; Knudson, C. A.; Morris, R. V.; Navarro-González, R.; Pavlov, A. A.; Plummer, R.; Rampe, E. B.; Stern, J. C.; Steele, A.; Summons, R. E.; Sutter, B.

2017-09-01

Variability in the sulfur isotopic composition in sediments can reflect atmospheric, geologic and biological processes. Evidence for ancient fluvio-lacustrine environments at Gale crater on Mars and a lack of efficient crustal recycling mechanisms on the planet suggests a surface environment that was once warm enough to allow the presence of liquid water, at least for discrete periods of time, and implies a greenhouse effect that may have been influenced by sulfur-bearing volcanic gases. Here we report in situ analyses of the sulfur isotopic compositions of SO2 volatilized from ten sediment samples acquired by NASA’s Curiosity rover along a 13 km traverse of Gale crater. We find large variations in sulfur isotopic composition that exceed those measured for Martian meteorites and show both depletion and enrichment in 34S. Measured values of δ34S range from -47 +/- 14‰ to 28 +/- 7‰, similar to the range typical of terrestrial environments. Although limited geochronological constraints on the stratigraphy traversed by Curiosity are available, we propose that the observed sulfur isotopic signatures at Gale crater can be explained by equilibrium fractionation between sulfate and sulfide in an impact-driven hydrothermal system and atmospheric processing of sulfur-bearing gases during transient warm periods.

What we have learned about Mars from SNC meteorites

Science.gov (United States)

Mcsween, Harry Y., Jr.

1994-01-01

lithosphere, but it is in isotopic equilibrium with the atmosphere and has been since 1.3 Ga. The isotopically heavy atmosphere/hydrosphere composition deduced from these rocks reflects a loss process more severe than current atmospheric evolution models, and the occurence of carbonates in SNC meteorites suggest that they, rather than scapolite or hydrous carbonates, are the major crustal sink for CO2. Weathering products in SNC meteorites support the idea of limited alteration of the lithosphere by small volumes of saline, CO2-bearing water. Atmospheric composition and evolution are further constrained by noble gases in these meteorites, although Xe and Kr isotopes suggest different origins for the atmosphere. Planetary ejection of these rocks has promoted an advance in the understanding of impact physics, which has been accomplished by a model involving spallation during large cratering events. Ejection of all the SNC meteorites (except ALH84001) in one or two events may provide a plausible solution to most constraints imposed by chronology, geochemistry, and cosmic ray exposure, although problems remain with this scenario; ALH84001 may represent older martian crust sampled during a separate impact.

STXM-XANES Analysis of Organic Matter in Dark Clasts and Halite Crystals in Zag and Monahans Meteorites

Science.gov (United States)

Kebukawa, Y.; Zolensky, M. E.; Fries, M.; Nakato, A.; Kilcoyne, A. L. D.; Takeichi, Y.; Suga, H.; Miyamoto, C.; Rahman, Z.; Kobayashi, K.;

Asteroid/meteorite streams

Science.gov (United States)

Drummond, J.

The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 meteorite producing fireballs presents the possibility of matching specific meteorites to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three meteorites with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant meteorite types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram meteorite and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree meteorite is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five meteorite-dropping fireballs and this one asteroid. The H5 Lost City meteorite is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four meteorite-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no meteorites have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated meteorites would provide an opportunity for in-hand analysis of a potential

Gully formation in terrestrial simple craters: Meteor Crater, USA and Lonar Crater, India

Science.gov (United States)

Kumar, P.; Head, J. W.; Kring, D. A.

2007-12-01

Geomorphic features such as gullies, valley networks, and channels on Mars have been used as a proxy to understand the climate and landscape evolution of Mars. Terrestrial analogues provide significant insight as to how the various exogenic and endogenic processes might contribute to the evolution of these martian landscapes. We describe here a terrestrial example from Meteor Crater, which shows a spectacular development of gullies throughout the inner wall in response to rainwater precipitation, snow melting and groundwater discharge. As liquid water has been envisaged as one of the important agents of landscape sculpturing, Meteor Crater remains a useful landmark, where planetary geologists can learn some lessons. We also show here how the lithology and structural framework of this crater controls the gully distribution. Like many martian impact craters, it was emplaced in layered sedimentary rocks with an exceptionally well-developed centripetal drainage pattern consisting of individual alcoves, channels and fans. Some of the gullies originate from the rim crest and others from the middle crater wall, where a lithologic transition occurs. Deeply incised alcoves are well-developed on the soft sandstones of the Coconino Formation exposed on the middle crater wall, beneath overlying dolomite. In general, the gully locations are along crater wall radial fractures and faults, which are favorable locales of groundwater flow and discharge; these structural discontinuities are also the locales where the surface runoff from rain precipitation and snow melting can preferentially flow, causing degradation. Like martian craters, channels are well developed on the talus deposits and alluvial fans on the periphery of the crater floor. In addition, lake sediments on the crater floor provide significant evidence of a past pluvial climate, when groundwater seeped from springs on the crater wall. Caves exposed on the lower crater level may point to percolation of surface runoff

Plasma and collision processes of hypervelocity meteorite impact in the prehistory of life

Science.gov (United States)

Managadze, G.

2010-07-01

A new concept is proposed, according to which the plasma and collision processes accompanying hypervelocity impacts of meteorites can contribute to the arising of the conditions on early Earth, which are necessary for the appearance of primary forms of living matter. It was shown that the processes necessary for the emergence of living matter could have started in a plasma torch of meteorite impact and have continued in an impact crater in the case of the arising of the simplest life form. It is generally accepted that planets are the optimal place for the origin and evolution of life. In the process of forming the planetary systems the meteorites, space bodies feeding planet growth, appear around stars. In the process of Earth's formation, meteorite sizes ranged from hundreds and thousands of kilometres. These space bodies consisted mostly of the planetesimals and comet nucleus. During acceleration in Earth's gravitational field they reached hypervelocity and, hitting the surface of planet, generated powerful blowouts of hot plasma in the form of a torch. They also created giant-size craters and dense dust clouds. These bodies were composed of all elements needed for the synthesis of organic compounds, with the content of carbon being up to 5%-15%. A new idea of possible synthesis of the complex organic compounds in the hypervelocity impact-generated plasma torch was proposed and experimentally confirmed. A previously unknown and experimentally corroborated feature of the impact-generated plasma torch allowed a new concept of the prehistory of life to be developed. According to this concept the intensive synthesis of complex organic compounds arose during meteoritic bombardment in the first 0.5 billion years at the stage of the planet's formation. This most powerful and destructive action in Earth's history could have played a key role and prepared conditions for the origin of life. In the interstellar gas-dust clouds, the synthesis of simple organic matter could

X-ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater

Science.gov (United States)

Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Morris, R. V.; Ming, D. W.; Treiman, A. H.; Sarrazin, P.; Morrison, S. M.; Downs, R. T.; Achilles, C. N.; Yen, A. S.; Bristow, T. F.; Crisp, J. A.; Morookian, J. M.; Farmer, J. D.; Rampe, E. B.; Stolper, E. M.; Spanovich, N.; Achilles, Cherie; Agard, Christophe; Verdasca, José Alexandre Alves; Anderson, Robert; Anderson, Ryan; Archer, Doug; Armiens-Aparicio, Carlos; Arvidson, Ray; Atlaskin, Evgeny; Atreya, Sushil; Aubrey, Andrew; Baker, Burt; Baker, Michael; Balic-Zunic, Tonci; Baratoux, David; Baroukh, Julien; Barraclough, Bruce; Bean, Keri; Beegle, Luther; Behar, Alberto; Bell, James; Bender, Steve; Benna, Mehdi; Bentz, Jennifer; Berger, Gilles; Berger, Jeff; Berman, Daniel; Bish, David; Blake, David F.; Avalos, Juan J. Blanco; Blaney, Diana; Blank, Jen; Blau, Hannah; Bleacher, Lora; Boehm, Eckart; Botta, Oliver; Böttcher, Stephan; Boucher, Thomas; Bower, Hannah; Boyd, Nick; Boynton, Bill; Breves, Elly; Bridges, John; Bridges, Nathan; Brinckerhoff, William; Brinza, David; Bristow, Thomas; Brunet, Claude; Brunner, Anna; Brunner, Will; Buch, Arnaud; Bullock, Mark; Burmeister, Sönke; Cabane, Michel; Calef, Fred; Cameron, James; Campbell, John "Iain"; Cantor, Bruce; Caplinger, Michael; Rodríguez, Javier Caride; Carmosino, Marco; Blázquez, Isaías Carrasco; Charpentier, Antoine; Chipera, Steve; Choi, David; Clark, Benton; Clegg, Sam; Cleghorn, Timothy; Cloutis, Ed; Cody, George; Coll, Patrice; Conrad, Pamela; Coscia, David; Cousin, Agnès; Cremers, David; Crisp, Joy; Cros, Alain; Cucinotta, Frank; d'Uston, Claude; Davis, Scott; Day, Mackenzie "Kenzie"; Juarez, Manuel de la Torre; DeFlores, Lauren; DeLapp, Dorothea; DeMarines, Julia; DesMarais, David; Dietrich, William; Dingler, Robert; Donny, Christophe; Downs, Bob; Drake, Darrell; Dromart, Gilles; Dupont, Audrey; Duston, Brian; Dworkin, Jason; Dyar, M. Darby; Edgar, Lauren; Edgett, Kenneth; Edwards, Christopher; Edwards, Laurence; Ehlmann, Bethany; Ehresmann, Bent; Eigenbrode, Jen; Elliott, Beverley; Elliott, Harvey; Ewing, Ryan; Fabre, Cécile; Fairén, Alberto; Farley, Ken; Farmer, Jack; Fassett, Caleb; Favot, Laurent; Fay, Donald; Fedosov, Fedor; Feldman, Jason; Feldman, Sabrina; Fisk, Marty; Fitzgibbon, Mike; Flesch, Greg; Floyd, Melissa; Flückiger, Lorenzo; Forni, Olivier; Fraeman, Abby; Francis, Raymond; François, Pascaline; Franz, Heather; Freissinet, Caroline; French, Katherine Louise; Frydenvang, Jens; Gaboriaud, Alain; Gailhanou, Marc; Garvin, James; Gasnault, Olivier; Geffroy, Claude; Gellert, Ralf; Genzer, Maria; Glavin, Daniel; Godber, Austin; Goesmann, Fred; Goetz, Walter; Golovin, Dmitry; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Gondet, Brigitte; Gordon, Suzanne; Gorevan, Stephen; Grant, John; Griffes, Jennifer; Grinspoon, David; Grotzinger, John; Guillemot, Philippe; Guo, Jingnan; Gupta, Sanjeev; Guzewich, Scott; Haberle, Robert; Halleaux, Douglas; Hallet, Bernard; Hamilton, Vicky; Hardgrove, Craig; Harker, David; Harpold, Daniel; Harri, Ari-Matti; Harshman, Karl; Hassler, Donald; Haukka, Harri; Hayes, Alex; Herkenhoff, Ken; Herrera, Paul; Hettrich, Sebastian; Heydari, Ezat; Hipkin, Victoria; Hoehler, Tori; Hollingsworth, Jeff; Hudgins, Judy; Huntress, Wesley; Hurowitz, Joel; Hviid, Stubbe; Iagnemma, Karl; Indyk, Steve; Israël, Guy; Jackson, Ryan; Jacob, Samantha; Jakosky, Bruce; Jensen, Elsa; Jensen, Jaqueline Kløvgaard; Johnson, Jeffrey; Johnson, Micah; Johnstone, Steve; Jones, Andrea; Jones, John; Joseph, Jonathan; Jun, Insoo; Kah, Linda; Kahanpää, Henrik; Kahre, Melinda; Karpushkina, Natalya; Kasprzak, Wayne; Kauhanen, Janne; Keely, Leslie; Kemppinen, Osku; Keymeulen, Didier; Kim, Myung-Hee; Kinch, Kjartan; King, Penny; Kirkland, Laurel; Kocurek, Gary; Koefoed, Asmus; Köhler, Jan; Kortmann, Onno; Kozyrev, Alexander; Krezoski, Jill; Krysak, Daniel; Kuzmin, Ruslan; Lacour, Jean Luc; Lafaille, Vivian; Langevin, Yves; Lanza, Nina; Lasue, Jeremie; Le Mouélic, Stéphane; Lee, Ella Mae; Lee, Qiu-Mei; Lees, David; Lefavor, Matthew; Lemmon, Mark; Malvitte, Alain Lepinette; Leshin, Laurie; Léveillé, Richard; Lewin-Carpintier, Éric; Lewis, Kevin; Li, Shuai; Lipkaman, Leslie; Little, Cynthia; Litvak, Maxim; Lorigny, Eric; Lugmair, Guenter; Lundberg, Angela; Lyness, Eric; Madsen, Morten; Mahaffy, Paul; Maki, Justin; Malakhov, Alexey; Malespin, Charles; Malin, Michael; Mangold, Nicolas; Manhes, Gérard; Manning, Heidi; Marchand, Geneviève; Jiménez, Mercedes Marín; García, César Martín; Martin, Dave; Martin, Mildred; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Mauchien, Patrick; Maurice, Sylvestre; McAdam, Amy; McCartney, Elaina; McConnochie, Timothy; McCullough, Emily; McEwan, Ian; McKay, Christopher; McLennan, Scott; McNair, Sean; Melikechi, Noureddine; Meslin, Pierre-Yves; Meyer, Michael; Mezzacappa, Alissa; Miller, Hayden; Miller, Kristen; Milliken, Ralph; Ming, Douglas; Minitti, Michelle; Mischna, Michael; Mitrofanov, Igor; Moersch, Jeff; Mokrousov, Maxim; Jurado, Antonio Molina; Moores, John; Mora-Sotomayor, Luis; Morookian, John Michael; Morris, Richard; Morrison, Shaunna; Mueller-Mellin, Reinhold; Muller, Jan-Peter; Caro, Guillermo Muñoz; Nachon, Marion; López, Sara Navarro; Navarro-González, Rafael; Nealson, Kenneth; Nefian, Ara; Nelson, Tony; Newcombe, Megan; Newman, Claire; Newsom, Horton; Nikiforov, Sergey; Niles, Paul; Nixon, Brian; Dobrea, Eldar Noe; Nolan, Thomas; Oehler, Dorothy; Ollila, Ann; Olson, Timothy; Owen, Tobias; Hernández, Miguel Ángel de Pablo; Paillet, Alexis; Pallier, Etienne; Palucis, Marisa; Parker, Timothy; Parot, Yann; Patel, Kiran; Paton, Mark; Paulsen, Gale; Pavlov, Alex; Pavri, Betina; Peinado-González, Verónica; Pepin, Robert; Peret, Laurent; Perez, Rene; Perrett, Glynis; Peterson, Joe; Pilorget, Cedric; Pinet, Patrick; Pla-García, Jorge; Plante, Ianik; Poitrasson, Franck; Polkko, Jouni; Popa, Radu; Posiolova, Liliya; Posner, Arik; Pradler, Irina; Prats, Benito; Prokhorov, Vasily; Purdy, Sharon Wilson; Raaen, Eric; Radziemski, Leon; Rafkin, Scot; Ramos, Miguel; Rampe, Elizabeth; Raulin, François; Ravine, Michael; Reitz, Günther; Rennó, Nilton; Rice, Melissa; Richardson, Mark; Robert, François; Robertson, Kevin; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio J.; Rowland, Scott; Rubin, David; Saccoccio, Muriel; Salamon, Andrew; Sandoval, Jennifer; Sanin, Anton; Fuentes, Sara Alejandra Sans; Saper, Lee; Sarrazin, Philippe; Sautter, Violaine; Savijärvi, Hannu; Schieber, Juergen; Schmidt, Mariek; Schmidt, Walter; Scholes, Daniel "Dan"; Schoppers, Marcel; Schröder, Susanne; Schwenzer, Susanne; Martinez, Eduardo Sebastian; Sengstacken, Aaron; Shterts, Ruslan; Siebach, Kirsten; Siili, Tero; Simmonds, Jeff; Sirven, Jean-Baptiste; Slavney, Susie; Sletten, Ronald; Smith, Michael; Sánchez, Pablo Sobrón; Spanovich, Nicole; Spray, John; Squyres, Steven; Stack, Katie; Stalport, Fabien; Steele, Andrew; Stein, Thomas; Stern, Jennifer; Stewart, Noel; Stipp, Susan Louise Svane; Stoiber, Kevin; Stolper, Ed; Sucharski, Bob; Sullivan, Rob; Summons, Roger; Sumner, Dawn; Sun, Vivian; Supulver, Kimberley; Sutter, Brad; Szopa, Cyril; Tan, Florence; Tate, Christopher; Teinturier, Samuel; ten Kate, Inge; Thomas, Peter; Thompson, Lucy; Tokar, Robert; Toplis, Mike; Redondo, Josefina Torres; Trainer, Melissa; Treiman, Allan; Tretyakov, Vladislav; Urqui-O'Callaghan, Roser; Van Beek, Jason; Van Beek, Tessa; VanBommel, Scott; Vaniman, David; Varenikov, Alexey; Vasavada, Ashwin; Vasconcelos, Paulo; Vicenzi, Edward; Vostrukhin, Andrey; Voytek, Mary; Wadhwa, Meenakshi; Ward, Jennifer; Webster, Chris; Weigle, Eddie; Wellington, Danika; Westall, Frances; Wiens, Roger Craig; Wilhelm, Mary Beth; Williams, Amy; Williams, Joshua; Williams, Rebecca; Williams, Richard B. "Mouser"; Wilson, Mike; Wimmer-Schweingruber, Robert; Wolff, Mike; Wong, Mike; Wray, James; Wu, Megan; Yana, Charles; Yen, Albert; Yingst, Aileen; Zeitlin, Cary; Zimdar, Robert; Mier, María-Paz Zorzano

2013-09-01

The Mars Science Laboratory rover Curiosity scooped samples of soil from the Rocknest aeolian bedform in Gale crater. Analysis of the soil with the Chemistry and Mineralogy (CheMin) x-ray diffraction (XRD) instrument revealed plagioclase (~An57), forsteritic olivine (~Fo62), augite, and pigeonite, with minor K-feldspar, magnetite, quartz, anhydrite, hematite, and ilmenite. The minor phases are present at, or near, detection limits. The soil also contains 27 ± 14 weight percent x-ray amorphous material, likely containing multiple Fe3+- and volatile-bearing phases, including possibly a substance resembling hisingerite. The crystalline component is similar to the normative mineralogy of certain basaltic rocks from Gusev crater on Mars and of martian basaltic meteorites. The amorphous component is similar to that found on Earth in places such as soils on the Mauna Kea volcano, Hawaii.

The Meteoritical Bulletin, No. 103

Science.gov (United States)

Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Agee, Carl B.

2017-05-01

Meteoritical Bulletin 103 contains 2582 meteorites including 10 falls (Ardón, Demsa, Jinju, Križevci, Kuresoi, Novato, Tinajdad, Tirhert, Vicência, Wolcott), with 2174 ordinary chondrites, 130 HED achondrites, 113 carbonaceous chondrites, 41 ureilites, 27 lunar meteorites, 24 enstatite chondrites, 21 iron meteorites, 15 primitive achondrites, 11 mesosiderites, 10 Martian meteorites, 6 Rumuruti chondrites, 5 ungrouped achondrites, 2 enstatite achondrites, 1 relict meteorite, 1 pallasite, and 1 angrite, and with 1511 from Antarctica, 588 from Africa, 361 from Asia, 86 from South America, 28 from North America, and 6 from Europe. Note: 1 meteorite from Russia was counted as European. The complete contents of this bulletin (244 pages) are available on line. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at meteor/">http://www.lpi.usra.edu/meteor/.

A Numerical Investigation into Low-Speed Impact Cratering Events

Science.gov (United States)

Schwartz, Stephen; Richardson, D. C.; Michel, P.

2012-10-01

Impact craters are the geological features most commonly observed on the surface of solid Solar System bodies. Crater shapes and features are crucial sources of information regarding past and present surface environments, and can provide indirect information about the internal structures of these bodies. In this study, we consider the effects of low-speed impacts into granular material. Studies of low-speed impact events are suitable for understanding the cratering process leading, for instance, to secondary craters. In addition, upcoming asteroid sample return missions will employ surface sampling strategies that use impacts into the surface by a projectile. An understanding of the process can lead to better sampling strategies. We use our implementation of the Soft-Sphere Discrete Element Method (SSDEM) (Schwartz et al. 2012, Granular Matter 14, 363-380) into the parallel N-body code PKDGRAV (cf. Richardson et al. 2011, Icarus 212, 427-437) to model the impact cratering process into granular material. We consider the effects of boundary conditions on the ejecta velocity profile and discuss how results relate to the Maxwell Z-Model during the crater growth phase. Cratering simulations are compared to those of Wada et al. 2006 (Icarus 180, 528-545) and to impact experiments performed in conjunction with Hayabusa 2. This work is supported in part by grants from the National Science Foundation under grant number AST1009579 and from the Office of Space Science of NASA under grant number NNX08AM39G. Part of this study resulted from discussions with the International Team (#202) sponsored by ISSI in Bern (Switzerland). Some simulations were performed on the YORP cluster administered by the Center for Theory and Computation of the Department of Astronomy at the University of Maryland in College Park and on the SIGGAM computer cluster hosted by the Côte d'Azur Observatory in Nice (France).

Foundations of Forensic Meteoritics

Science.gov (United States)

Treiman, A. H.

1992-07-01

It may be useful to know if a meteorite was found at the site where it fell. For instance, the polymict ureilites North Haig and Nilpena were found 1100 km apart, yet are petrologically identical [1]. Could this distance represent transport from a single strewn field, or does it represent distinct fall sites? A meteorite may contain sufficient clues to suggest some characteristics of its fall site. If these inferences are inconsistent with the find site, one may infer that the meteorite has been transported. It will likely be impossible to determine the exact fall site of a transported meteorite. Data relevant to a meteorite's fall site may be intrinsic to the meteorite, or acquired at the site. For instance, an intrinsic property is terrestrial residence age (from abundances of cosmogenic radioisotopes and their decay products); a meteorite's terrestrial residence age must be the same or less than that of the surface on which it fell. After falling, a meteorite may acquire characteristic telltales of terrestrial geological, geochemical, and biological processes. These telltale clues may include products of chemical weathering, adhering geological materials, biological organisms living (or once living) on the meteorite, and biological materials adhering to (but never living on) the meteorite. The effects of chemical weathering, present in all but the freshest finds, range from slight rusting to extensive decomposition and veining The ages of weathering materials and veins, as with terrestrial residence ages above, must be less than the age of the fall surface. The mineralogy and chemistry, elemental and isotopic, of weathering materials will differ according to the mineralogy and composition of the meteorite, and the mineralogy, geochemistry, hydrology, and climate of the fall site. Weathering materials may also vary as climate changes and may vary among the microenvironments associated with a meteorite on the Earth's surface. Geological materials (rock, sediment

Geological Structures in the WaIls of Vestan Craters

Science.gov (United States)

Mittlefehldt, David; Nathues, A.; Beck, A. W.; Hoffmann, M.; Schaefer, M.; Williams, D. A.

2014-01-01

A compelling case can be made that Vesta is the parent asteroid for the howardite, eucrite and diogenite (HED) meteorites [1], although this interpretation has been questioned [2]. Generalized models for the structure of the crust of Vesta have been developed based on petrologic studies of basaltic eucrites, cumulate eucrites and diogenites. These models use inferred cooling rates for different types of HEDs and compositional variations within the clan to posit that the lower crust is dominantly diogenitic in character, cumulate eucrites occur deep in the upper crust, and basaltic eucrites dominate the higher levels of the upper crust [3-5]. These models lack fine-scale resolution and thus do not allow for detailed predictions of crustal structure. Geophysical models predict dike and sill intrusions ought to be present, but their widths may be quite small [6]. The northern hemisphere of Vesta is heavily cratered, and the southern hemisphere is dominated by two 400-500 km diameter basins that excavated deep into the crust [7-8]. Physical modeling of regolith formation on 300 km diameter asteroids predicts that debris layers would reach a few km in thickness, while on asteroids of Vesta's diameter regolith thicknesses would be less [9]. This agrees well with the estimated =1 km thickness of local debris excavated by a 45 km diameter vestan crater [10]. Large craters and basins may have punched through the regolith/megaregolith and exposed primary vestan crustal structures. We will use Dawn Framing Camera (FC) [11] images and color ratio maps from the High Altitude and Low Altitude Mapping Orbits (HAMO, 65 m/pixel; LAMO, 20 m/pixel) to evaluate structures exposed on the walls of craters: two examples are discussed here.

Study of melt produced bodies observed at Henbury crater region

International Nuclear Information System (INIS)

Hopper, V.D.; Sewell, D.K.B.; Aitken, D.K.

1989-01-01

Spherical and non spherical bodies derived from target rock and meteorite components have been found in samples of soil in the Henbury crater region. From a study of the composition of these bodies, the compositions of the meteorite and the target rock, it has been possible to separate the bodies into three groups showing differing degrees of volatilization of various oxides. The composition of a number of the soil samples were measured using X-ray fluorescence. A selected number were then examined by a scanning electron microscope fitted with an energy dispersive X-ray analyzer. Where Ni was definitely identified, it was examined by an electron microprobe X-ray analyzer. A major finding was the depletion of SiO 2 in the production of both Group 1 and Group 3 bodies. Group 3 bodies are not volatilized to the same extent as Group 1. With no reference to the target rock , the general order of volatility appears to be Na 2 O>MgO>K 2 O>TiO 2 , SiO 2 and Al 2 O 3 , the significant change being the place of SiO2. 13 refs., 7 figs., 5 tabs

Antarctic Meteorite Newsletter

Science.gov (United States)

Lindstrom, Marilyn

2000-01-01

This newsletter contains something for everyone! It lists classifications of about 440 meteorites mostly from the 1997 and 1998 ANSMET (Antarctic Search for Meteorites) seasons. It also gives descriptions of about 45 meteorites of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).

Iron and stony-iron meteorites

DEFF Research Database (Denmark)

Ruzicka, Alex M.; Haack, Henning; Chabot, Nancy L.

2017-01-01

By far most of the melted and differentiated planetesimals that have been sampled as meteorites are metal-rich iron meteorites or stony iron meteorites. The parent asteroids of these meteorites accreted early and differentiated shortly after the solar system formed, producing some of the oldest...... and interpretations for iron and stony iron meteorites (Plate 13.1). Such meteorites provide important constraints on the nature of metal-silicate separation and mixing in planetesimals undergoing partial to complete differentiation. They include iron meteorites that formed by the solidification of cores...... (fractionally crystallized irons), irons in which partly molten metal and silicates of diverse types were mixed together (silicate-bearing irons), stony irons in which partly molten metal and olivine from cores and mantles were mixed together (pallasites), and stony irons in which partly molten metal...

Meteorites as space probes

International Nuclear Information System (INIS)

Jaques, A.L.

1982-01-01

Meteorites are a major source of information on evolution of the solar system. The BMR-Hollmayer meteorite collection consists mainly of chondrites but also includes a carbonaceous chondrite and a ureilite from the achondrite group. The mineralogy and chemical composition of the meteorites have been studied

Organic Molecules in Meteorites

Science.gov (United States)

Martins, Zita

2015-08-01

Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10] Elsila et al. (2005) GCA 5, 1349. [11] Glavin and Dworkin (2009) PNAS 106, 5487. [12] Pizzarello et al. (2003) GCA 67, 1589. [13] Chan et al. (2012) MAPS. 47, 1502

Lunar Meteorites: A Global Geochemical Dataset

Science.gov (United States)

Zeigler, R. A.; Joy, K. H.; Arai, T.; Gross, J.; Korotev, R. L.; McCubbin, F. M.

2017-01-01

To date, the world's meteorite collections contain over 260 lunar meteorite stones representing at least 120 different lunar meteorites. Additionally, there are 20-30 as yet unnamed stones currently in the process of being classified. Collectively these lunar meteorites likely represent 40-50 distinct sampling locations from random locations on the Moon. Although the exact provenance of each individual lunar meteorite is unknown, collectively the lunar meteorites represent the best global average of the lunar crust. The Apollo sites are all within or near the Procellarum KREEP Terrane (PKT), thus lithologies from the PKT are overrepresented in the Apollo sample suite. Nearly all of the lithologies present in the Apollo sample suite are found within the lunar meteorites (high-Ti basalts are a notable exception), and the lunar meteorites contain several lithologies not present in the Apollo sample suite (e.g., magnesian anorthosite). This chapter will not be a sample-by-sample summary of each individual lunar meteorite. Rather, the chapter will summarize the different types of lunar meteorites and their relative abundances, comparing and contrasting the lunar meteorite sample suite with the Apollo sample suite. This chapter will act as one of the introductory chapters to the volume, introducing lunar samples in general and setting the stage for more detailed discussions in later more specialized chapters. The chapter will begin with a description of how lunar meteorites are ejected from the Moon, how deep samples are being excavated from, what the likely pairing relationships are among the lunar meteorite samples, and how the lunar meteorites can help to constrain the impactor flux in the inner solar system. There will be a discussion of the biases inherent to the lunar meteorite sample suite in terms of underrepresented lithologies or regions of the Moon, and an examination of the contamination and limitations of lunar meteorites due to terrestrial weathering. The

Meteorite falls in Africa

Science.gov (United States)

Khiri, Fouad; Ibhi, Abderrahmane; Saint-Gerant, Thierry; Medjkane, Mohand; Ouknine, Lahcen

2017-10-01

The study of meteorites provides insight into the earliest history of our solar system. From 1800, about the year meteorites were first recognized as objects falling from the sky, until December 2014, 158 observed meteorite falls were recorded in Africa. Their collected mass ranges from 1.4 g to 175 kg with the 1-10 kg cases predominant. The average rate of African falls is low with only one fall recovery per 1.35-year time interval (or 0.023 per year per million km2). This African collection is dominated by ordinary chondrites (78%) just like in the worldwide falls. The seventeen achondrites include three Martian meteorite falls (Nakhla of Egypt, Tissint of Morocco and Zagami of Nigeria). Observed Iron meteorite falls are relatively rare and represent only 5%. The falls' rate in Africa is variable in time and in space. The number of falls continues to grow since 1860, 80% of which were recovered during the period between 1910 and 2014. Most of these documented meteorite falls have been recovered from North-Western Africa, Eastern Africa and Southern Africa. They are concentrated in countries which have a large surface area and a large population with a uniform distribution. Other factors are also favorable for observing and collecting meteorite falls across the African territory, such as: a genuine meteorite education, a semi-arid to arid climate (clear sky throughout the year most of the time), croplands or sparse grasslands and possible access to the fall location with a low percentage of forest cover and dense road network.

Meteors, meteorites and cosmic dust

International Nuclear Information System (INIS)

Lebedinets, V.N.

1987-01-01

The problem of meteorite origin and meteorite composition is discussed. Nowadays, most scientists suppose that the giant Oort cloud consisting of ice comet nuclei is the sourse of the meteor matter. A principle unity of the matter of meteorites falling to the Earth and cosmic dust is noted as well as that of meteorite bodies evaporating in the atmosphere and bearing meteors and bodies

The Microstructure of Lunar Micrometeorite Impact Craters

Science.gov (United States)

Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

2016-01-01

The peak of the mass flux of impactors striking the lunar surface is made up of objects approximately 200 micrometers in diameter that erode rocks, comminute regolith grains, and produce agglutinates. The effects of these micro-scale impacts are still not fully understood. Much effort has focused on evaluating the physical and optical effects of micrometeorite impacts on lunar and meteoritic material using pulsed lasers to simulate the energy deposited into a substrate in a typical hypervelocity impact. Here we characterize the physical and chemical changes that accompany natural micrometeorite impacts into lunar rocks with long surface exposure to the space environment (12075 and 76015). Transmission electron microscope (TEM) observations were obtained from cross-sections of approximately 10-20 micrometers diameter craters that revealed important micro-structural details of micrometeorite impact processes, including the creation of npFe (sup 0) in the melt, and extensive deformation around the impact site.

Antarctic Meteorite Classification and Petrographic Database

Science.gov (United States)

Todd, Nancy S.; Satterwhite, C. E.; Righter, Kevin

2011-01-01

The Antarctic Meteorite collection, which is comprised of over 18,700 meteorites, is one of the largest collections of meteorites in the world. These meteorites have been collected since the late 1970's as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s Meteorite Lab and the Smithsonian Institution and results are published twice a year in the Antarctic Meteorite Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these meteorites is also published on the NASA Curation website [2] and made available through the Meteorite Classification Database allowing scientists to search by a variety of parameters

Meteorites, Ice, and Antarctica

Science.gov (United States)

Cassidy, William A.

2003-08-01

Bill Cassidy led meteorite recovery expeditions in the Antarctic for fifteen years and his searches have resulted in the collection of thousands of meteorite specimens from the ice. This personal account of his field experiences on the U.S. Antarctic Search for Meteorites Project reveals the influence the work has had on our understanding of the moon, Mars and the asteroid belt. Cassidy describes the hardships and dangers of fieldwork in a hostile environment, as well as the appreciation he developed for its beauty. William Cassidy is Emeritus Professor of Geology and Planetary Science at the University of Pittsburgh. He initiated the U.S. Antarctic Search for Meteorites (ANSMET) nroject and led meteorite recovery expeditions in Antarctica in1976. His name is found attached to a mineral (cassidyite), on the map of Antarctica (Cassidy Glacier), and in the Catalog of Asteroids (3382 Cassidy). Profiled in "American Men of Science," and "Who's Who in America," he is also a recipient of The Antarctic Service Medal from the United States and has published widely in Science, Meteoritics and Planetary Science, and The Journal of Geophysical Research.

Degraded Crater Rim

Science.gov (United States)

2002-01-01

(Released 3 May 2002) The Science The eastern rim of this unnamed crater in Southern Arabia Terra is very degraded (beaten up). This indicates that this crater is very ancient and has been subjected to erosion and subsequent bombardment from other impactors such as asteroids and comets. One of these later (younger) craters is seen in the upper right of this image superimposed upon the older crater rim material. Note that this smaller younger crater rim is sharper and more intact than the older crater rim. This region is also mantled with a blanket of dust. This dust mantle causes the underlying topography to take on a more subdued appearance. The Story When you think of Arabia, you probably think of hot deserts and a lot of profitable oil reserves. On Mars, however, Southern Arabia Terra is a cold place of cratered terrain. This almost frothy-looking image is the badly battered edge of an ancient crater, which has suffered both erosion and bombardment from asteroids, comets, or other impacting bodies over the long course of its existence. A blanket of dust has also settled over the region, which gives the otherwise rugged landscape a soft and more subdued appearance. The small, round crater (upper left) seems almost gemlike in its setting against the larger crater ring. But this companionship is no easy romance. Whatever formed the small crater clearly whammed into the larger crater rim at some point, obliterating part of its edge. You can tell the small crater was formed after the first and more devastating impact, because it is laid over the other larger crater. How much younger is the small one? Well, its rim is also much sharper and more intact, which gives a sense that it is probably far more youthful than the very degraded, ancient crater.

Antarctic Martian Meteorites at Johnson Space Center

Science.gov (United States)

Funk, R. C.; Satterwhite, C. E.; Righter, K.; Harrington, R.

2018-01-01

This past year marked the 40th anniversary of the first Martian meteorite found in Antarctica by the ANSMET Antarctic Search for Meteorites) program, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET program making for a total of 15 Martian meteorites in the U. S. Antarctic meteorite collection at Johnson Space Center (JSC). Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate samples. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottite in 1982. This meteorite has been allocated to 137 scientists for research and there are 180.934 g remaining at JSC. Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain noble gas and nitrogen compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to 205 scientists for research and 5,298.435 g of sample is available.

Magnetism in meteorites

Science.gov (United States)

Herndon, J. M.; Rowe, M. W.

1974-01-01

An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.

Organics In Meteorites

Science.gov (United States)

Chang, Sherwood

1996-01-01

The variety of classes of organic compounds that occur in carbonaceous meteorites suggests a rich pre-planetary chemistry with possible connections to interstellar, solar nebular and parent body processes. Structural diversity prevails within all classes examined in detail. Among amino acids for instance, all possible isomers are found up to species containing 4-6 carbon atoms, with abundances decreasing with increasing molecular weight. Such diversity seems limited to those carbonaceous meteorites which show evidence of having been exposed to liquid water; meteorites lacking such evidence also show much lower abundances and less structural diversity in their organic contents. This apparent dependency on water suggests a role for cometary ices in the chemical evolution of organic compounds on parent bodies. Measurements of the stable isotope compositions of C, H, N and S in classes of compounds and at the individual compound level show strong deviations from average chondritic values. These deviations are difficult to explain by solar system or parent body processes, and precedents for some of these isotopic anomalies exist in interstellar (e.g., high D/H ratios) and circumstellar chemistry. Therefore, presolar origins for much if not all of the meteoritic organic compounds (or their precursors) is a distinct possibility. In contrast, evidence of solar nebular origins is either lacking or suspect. Results from molecular and isotopic analyses of meteoritic organics, from laboratory simulations and from a model of interstellar grain reactions will be used to flesh out the hypothesis that this material originated with interstellar chemistry, was distributed within the early solar system as cometary ices, and was subsequently altered on meteorite parent bodies to yield the observed compounds.

The Age of Lunar South Circumpolar Craters Haworth, Shoemaker, Faustini, and Shackleton: Implications for Regional Geology, Surface Processes, and Volatile Sequestration

Science.gov (United States)

Tye, A. R.; Fassett, C. I.; Head, J. W.; Mazarico, E.; Basilevsky, A. T.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

2015-01-01

The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size-frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D greater than or equal to 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D greater than or equal to 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slopedependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have approximately 1-2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have approximately 5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (approximately 3.5 Ga) crater retention ages of their

Stable isotope genealogy of meteorites

International Nuclear Information System (INIS)

Pillinger, C.T.

1988-01-01

One of the oldest problems in meteoritics is that of taxonomically grouping samples. In recent years the use of isotopes, particularly oxygen isotopes has proved very successful in this respect. Other light-element systematics potentially can perform the same function. For example, nitrogen in iron meteorites, and nitrogen and carbon in ureilites and SNC meteorites. These measurements will serve to extend and augment existing classification schemes and provide clues to the nature of meteorite parent bodies. They can also aid in the recognition of the isotopic signatures relating to inaccessible regions of the Earth. (author)

HYDROGEN CYANIDE IN THE MURCHISON METEORITE

Energy Technology Data Exchange (ETDEWEB)

Pizzarello, Sandra, E-mail: pizzar@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85018-1604 (United States)

2012-08-01

Carbonaceous chondrites are meteorites that may contain abundant organic materials, including soluble compounds as diverse as amino acids and hydrocarbons. We report here the finding of hydrogen cyanide in the Murchison meteorite in amounts {<=} 10 ppm. HCN was never searched for in meteorites and its detection in sizeable amount is surprising in view of the extensive water phase that is recorded by the petrology of this type of meteorites and could have exhausted their HCN content through multiple reactions. The finding adds to the inventory of simple volatile molecules found in both comets and meteorites.

Mysterious iodine-overabundance in Antarctic meteorites

Science.gov (United States)

Dreibus, G.; Waenke, H.; Schultz, L.

1986-01-01

Halogen as well as other trace element concentrations in meteorite finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic meteorites offered the opportunity to study meteorites which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic meteorites was compared with non-Antarctic meteorites. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed.

Mysterious iodine-overabundance in Antarctic meteorites

International Nuclear Information System (INIS)

Dreibus, G.; Waenke, H.; Schultz, L.

1986-01-01

Halogen as well as other trace element concentrations in meteorite finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic meteorites offered the opportunity to study meteorites which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic meteorites was compared with non-Antarctic meteorites. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed

Moessbauer study of El-Bahrain meteorite

International Nuclear Information System (INIS)

Bahgat, A.A.; Ahmed, M.A.; Ramadan, T.M.

2000-01-01

A stone of brick-like shape, measuring roughly 25 x 12.5 x 10.5 cm 3 and weighing 14 kg was found in 1983, in the western desert of Egypt. The meteorite was named El-Bahrain meteorite and classified as L-chondrite. Principal constituents of El-Bahrain meteorite have been studied by means of Moessbauer spectroscopy. The chemical composition as obtained by the conventional wet analyses of L-chondritic meteorites showed that the meteorite contains 23,38% Fe and 1.23% Ni. While the analysis of the atomic absorption showed the presence of 27.03% as a total iron. The Moessbauer analysis of El-Bahrain meteorite showed that the iron constituent minerals were determined to be olivine, metallic iron-nickel alloys (kamacite, taenite and tetrataenite), ferrous sulfide (troilite) and weathering products such as maghemite and nanocrystalline hematite. The structure of meteoritic iron obtained by the Moessbauer analysis has been discussed on the basis of these constituents. (author)

Annual Occurrence of Meteorite-Dropping Fireballs

Science.gov (United States)

Konovalova, Natalia; Jopek, Tadeusz J.

2016-07-01

The event of Chelyabinsk meteorite has brought about change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the meteorite. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of meteorites with the known fall dates and of the meteorite-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of meteorites and meteorite-dropping fireballs shows several periods of increased activity in the course of the year. The analysis of the atmospheric trajectories and physical properties of sporadic meteorite-dropping fireballs observed in Tajikistan by instrumental methods in the summer‒autumn periods of increased fireballs activity has been made. As a result the structural strength, the bulk density and terminal mass of the studied fireballs that can survive in the Earth atmosphere and became meteorites was obtained. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by D-criterion of Southworth and Hawkins the fireballs that could be the members of group of meteorite-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for meteorite-dropping fireballs was made and the evolution of orbits of these objects in the past on a long interval of time was investigated.

Dome craters on Ganymede

International Nuclear Information System (INIS)

Moore, J.M.; Malin, M.C.

1987-01-01

Voyager observations reveal impact craters on Ganymede that are characterized by the presence of broad, high albedo, topographic domes situated within a central pit. Fifty-seven craters with central domes were identified in images covering approx. 50% of the surface. Owing to limitations in resolution, and viewing and illumination angles, the features identified are most likely a subset of dome craters. The sample appears to be sufficiently large to infer statistically meaningful trends. Dome craters appear to fall into two distinct populations on plots of the ratio of dome diameter to crater rim diameter, large-dome craters and small-dome craters. The two classes are morphologically distinct from one another. In general, large dome craters show little relief and their constituent landforms appear subdued with respect to fresh craters. The physical attributes of small-dome craters are more sharply defined, a characteristic they share with young impact craters of comparable size observed elsewhere in the solar system. Both types of dome craters exhibit central pits in which the dome is located. As it is difficult to produce domes by impact and/or erosional processes, an endogenic origin for the domes is reasonably inferred. Several hypotheses for their origin are proposed. These hypotheses are briefly reviewed

Interpretation of Wild 2 Dust Fine Structure: Comparison of Stardust Aluminium Foil Craters to the Three-Dimensional Shape of Experimental Impacts by Artificial Aggregate Particles and Meteorite Powders

Energy Technology Data Exchange (ETDEWEB)

Kearsley, A T; Burchell, M J; Price, M C; Graham, G A; Wozniakiewicz, P J; Cole, M J; Foster, N J; Teslich, N

2009-12-10

New experimental results show that Stardust crater morphology is consistent with interpretation of many larger Wild 2 dust grains being aggregates, albeit most of low porosity and therefore relatively high density. The majority of large Stardust grains (i.e. those carrying most of the cometary dust mass) probably had density of 2.4 g cm{sup -3} (similar to soda-lime glass used in earlier calibration experiments) or greater, and porosity of 25% or less, akin to consolidated carbonaceous chondrite meteorites, and much lower than the 80% suggested for fractal dust aggregates. Although better size calibration is required for interpretation of the very smallest impacting grains, we suggest that aggregates could have dense components dominated by {micro}m-scale and smaller sub-grains. If porosity of the Wild 2 nucleus is high, with similar bulk density to other comets, much of the pore-space may be at a scale of tens of micrometers, between coarser, denser grains. Successful demonstration of aggregate projectile impacts in the laboratory now opens the possibility of experiments to further constrain the conditions for creation of bulbous (Type C) tracks in aerogel, which we have observed in recent shots. We are also using mixed mineral aggregates to document differential survival of pristine composition and crystalline structure in diverse fine-grained components of aggregate cometary dust analogues, impacted onto both foil and aerogel under Stardust encounter conditions.

Diradicaloids in the insoluble organic matter from the Tagish Lake meteorite: Comparison with the Orgueil and Murchison meteorites

Science.gov (United States)

Binet, L.; Gourier, D.; Derenne, S.; Pizzarello, S.; Becker, L.

2004-10-01

The radicals in the insoluble organic matter (IOM) from the Tagish Lake meteorites were studied by electron paramagnetic resonance and compared to those existing in the Orgueil and Murchison meteorites. As in the Orgueil and Murchison meteorites, the radicals in the Tagish Lake meteorite are heterogeneously distributed and comprise a substantial amount (~42%) of species with a thermally acessible triplet state and with the same singlet-triplet gap, ?E ??0.1 eV, as in the Orgueil and Murchison meteorites. These species were identified as diradicaloid moieties. The existence of similar diradicaloid moieties in three different carbonaceous chondrites but not in terrestrial IOM strongly suggests that these moieties could be "fingerprints" of the extraterrestrial origin of meteoritic IOM and markers of its synthetic pathway before its inclusion into a parent body.

Opportunity Mars Rover mission: Overview and selected results from Purgatory ripple to traverses to Endeavour crater

Science.gov (United States)

Arvidson, R. E.; Ashley, James W.; Bell, J.F.; Chojnacki, M.; Cohen, J.; Economou, T.E.; Farrand, W. H.; Fergason, R.; Fleischer, I.; Geissler, P.; Gellert, Ralf; Golombek, M.P.; Grotzinger, J.P.; Guinness, E.A.; Haberle, R.M.; Herkenhoff, K. E.; Herman, J.A.; Iagnemma, K.D.; Jolliff, B.L.; Johnson, J. R.; Klingelhofer, G.; Knoll, A.H.; Knudson, A.T.; Li, R.; McLennan, S.M.; Mittlefehldt, D. W.; Morris, R.V.; Parker, T.J.; Rice, M.S.; Schroder, C.; Soderblom, L.A.; Squyres, S. W.; Sullivan, R.J.; Wolff, M.J.

2011-01-01

Opportunity has been traversing the Meridiani plains since 25 January 2004 (sol 1), acquiring numerous observations of the atmosphere, soils, and rocks. This paper provides an overview of key discoveries between sols 511 and 2300, complementing earlier papers covering results from the initial phases of the mission. Key new results include (1) atmospheric argon measurements that demonstrate the importance of atmospheric transport to and from the winter carbon dioxide polar ice caps; (2) observations showing that aeolian ripples covering the plains were generated by easterly winds during an epoch with enhanced Hadley cell circulation; (3) the discovery and characterization of cobbles and boulders that include iron and stony-iron meteorites and Martian impact ejecta; (4) measurements of wall rock strata within Erebus and Victoria craters that provide compelling evidence of formation by aeolian sand deposition, with local reworking within ephemeral lakes; (5) determination that the stratigraphy exposed in the walls of Victoria and Endurance craters show an enrichment of chlorine and depletion of magnesium and sulfur with increasing depth. This result implies that regional-scale aqueous alteration took place before formation of these craters. Most recently, Opportunity has been traversing toward the ancient Endeavour crater. Orbital data show that clay minerals are exposed on its rim. Hydrated sulfate minerals are exposed in plains rocks adjacent to the rim, unlike the surfaces of plains outcrops observed thus far by Opportunity. With continued mechanical health, Opportunity will reach terrains on and around Endeavour's rim that will be markedly different from anything examined to date. Copyright 2011 by the American Geophysical Union.

Detection of a meteorite 'stream' - Observations of a second meteorite fall from the orbit of the Innisfree chondrite

Science.gov (United States)

Halliday, I.

1987-03-01

The first observational evidence of multiple meteorite falls from the same orbit is adduced from the February 6, 1980 fall of a meteorite precisely 3 yr after the fall of the Innisfree meteorite. Due consideration of the detection probability for two related objects with the meteorite camera network in western Canada suggests that the Innisfree brecciated LL chondrite was a near-surface fragment from a parent object whose radius was of the order of several tens of meters. A meteorite mass of 1.8 kg is predicted for the new object, whose recovery in the vicinity of Ridgedale, Saskatchewan, is now sought for the sake of comparison with the Innisfree chondrite.

Curation of US Martian Meteorites Collected in Antarctica

Science.gov (United States)

Lindstrom, M.; Satterwhite, C.; Allton, J.; Stansbury, E.

1998-01-01

To date the ANSMET field team has collected five martian meteorites (see below) in Antarctica and returned them for curation at the Johnson Space Center (JSC) Meteorite Processing Laboratory (MPL). ne meteorites were collected with the clean procedures used by ANSMET in collecting all meteorites: They were handled with JSC-cleaned tools, packaged in clean bags, and shipped frozen to JSC. The five martian meteorites vary significantly in size (12-7942 g) and rock type (basalts, lherzolites, and orthopyroxenite). Detailed descriptions are provided in the Mars Meteorite compendium, which describes classification, curation and research results. A table gives the names, classifications and original and curatorial masses of the martian meteorites. The MPL and measures for contamination control are described.

Ground penetrating radar geologic field studies of the ejecta of Barringer Meteorite Crater, Arizona, as a planetary analog

Science.gov (United States)

Russell, Patrick S.; Grant, John A.; Williams, Kevin K.; Carter, Lynn M.; Brent Garry, W.; Daubar, Ingrid J.

2013-09-01

penetrating radar (GPR) has been a useful geophysical tool in investigating a variety of shallow subsurface geological environments on Earth. Here we investigate the capabilities of GPR to provide useful geologic information in one of the most common geologic settings of planetary surfaces, impact crater ejecta. Three types of ejecta are surveyed with GPR at two wavelengths (400 MHz, 200 MHz) at Meteor Crater, Arizona, with the goal of capturing the GPR signature of the subsurface rock population. In order to "ground truth" the GPR characterization, subsurface rocks are visually counted and measured in preexisting subsurface exposures immediately adjacent to and below the GPR transect. The rock size-frequency distribution from 10 to 50 cm based on visual counts is well described by both power law and exponential functions, the former slightly better, reflecting the control of fragmentation processes during the impact-ejection event. GPR counts are found to overestimate the number of subsurface rocks in the upper meter (by a factor of 2-3x) and underestimate in the second meter of depth (0.6-1.0x), results attributable to the highly scattering nature of blocky ejecta. Overturned ejecta that is fractured yet in which fragments are minimally displaced from their complement fragments produces fewer GPR returns than well-mixed ejecta. The use of two wavelengths and division of results into multiple depth zones provides multiple aspects by which to characterize the ejecta block population. Remote GPR measurement of subsurface ejecta in future planetary situations with no subsurface exposure can be used to characterize those rock populations relative to that of Meteor Crater.

Meteorites and the Evolution of Our Solar System

Science.gov (United States)

Nava, David F.

1999-01-01

The study of meteorites has long been of intense interest ever since these objects were discovered to be of extraterrestrial origin. Meteorite research contributes to unraveling the mysteries in understanding the formation and evolution processes of our solar system. Meteorites, of which there are a variety of widely diverse types of chemical and mineralogical compositions, are the most ancient of solar system objects that can be studied in the laboratory. They preserve a unique historical record of the astronomical and astrophysical events of our solar system. This record is being discerned by a host of ever evolving analytical laboratory methods. Recent discoveries of what are believed to be Martian meteorites, lunar meteorites, a meteorite containing indigenous water, and the recovery from the Cretaceous layer of a small meteorite fragment thought to be from the dinosaur-killing asteroid have fueled additional excitement for studying meteorites.

Organic Chemistry of Meteorites

Science.gov (United States)

Chang, S.; Morrison, David (Technical Monitor)

1994-01-01

Studies of the molecular structures and C,N,H-isotopic compositions of organic matter in meteorites reveal a complex history beginning in the parent interstellar cloud which spawned the solar system. Incorporation of interstellar dust and gas in the protosolar nebula followed by further thermal and aqueous processing on primordial parent bodies of carbonaceous, meteorites have produced an inventory of diverse organic compounds including classes now utilized in biochemistry. This inventory represents one possible set of reactants for chemical models for the origin of living systems on the early Earth. Evidence bearing on the history of meteoritic organic matter from astronomical observations and laboratory investigations will be reviewed and future research directions discussed.

Antarctic Meteorite Newsletter. Volume 20

Science.gov (United States)

Lindstrom, Marilyn M.; Satterwhite, Cecilia E.

1997-01-01

The availability of 116 new meteorites from the 1994-1996 collections is announced. There are 4 special chondrites, 2 carbonaceous chondrites, and 1 achondrite among the new meteorites. Also included is a redescription of Lodranite GRA95209.

Contemporary Inuit Traditional Beliefs Concerning Meteorites

Science.gov (United States)

Mardon, A. A.; Mardon, E. G.; Williams, J. S.

1992-07-01

Inuit religious mythology and the importance of meteorites as "messages" from the Creator of all things is only now being recognized. Field investigations near Resolute, Cornwallis Island in the high Canadian Arctic in 1988 are the bases for this paper. Through interpreters, several elders of the local Inuit described in detail the Inuit belief, recognition, and wonder at the falling meteors & meteorites during the long Polar Night and Polar Day. Such events are passed on in the oral tradition from generation to generation by the elders and especially those elders who fulfill the shamanistic roles. The Inuit have come across rocks that they immediately recognize as not being "natural" and in the cases of a fall that was observed and the rock recovered the meteorite is kept either on the person or in some hidden niche known only to that person. In one story recounted a meteorite fell and was recovered at the birth of one very old elder and the belief was that if the rock was somehow damaged or taken from his possession he would die. Some indirect indication also was conveyed that the discovery and possession of meteorites allow shaman to have "supernatural" power. This belief in the supernatural power of meteorites can be seen historically in many societies, including Islam and the "black rock" (Kaaba) of Mecca. It should also be noted, however, that metallic meteorites were clearly once the major source of iron for Eskimo society as is indicated from the recovery of meteoritical iron arrow heads and harpoon heads from excavated pre-Viking contact sites. The one evident thing that became clear to the author is that the Inuit distinctly believe that these meteorites are religious objects of the highest order and it brings into question the current academic practice of sending meteorites south to research institutes. Any seeming conflict with the traditional use of meteoric iron is more apparent than real--the animals, the hunt, and the act of survival--all being

Quantitative FT-IR Analysis for Chondritic Meteorites: Search for C_60 in Meteorites

Directory of Open Access Journals (Sweden)

Chunglee Kim

1998-06-01

Full Text Available Infrared absorption spectra of 9 bulk samples and 3 acid residues of meteorites were obtained in the mid-infrared region (4000 ~ 400 cm^(-1. From the known composition of meteorites studied, the possible absorption modes were investigated. Most bands of bulk samples occur in the region below 1200 cm^(-1 and they are due to metallic oxides and silicates. The spectra of each group can be distinguished by its own characteristic bands. Acid residues show very distinct features from their bulk samples, and absorption bands due to organic compounds are not evident in their spectra. Quantitative analyses for two carbonaceous (Allende CV3 and Murchison CM2 and one ordinary (Carraweena L3.9 chondrites were performed for the presence of fullerene (C_60 in the meteorites. We calculated the concentration of C_60 in the acid residues by curvefitting the spectra with Gaussian functions. The upper limit of C_60 concentration in these meteorites appears to be less than an order of a few hundred ppm.

Centrifuge impact cratering experiment 5

Science.gov (United States)

1984-01-01

Transient crates motions, cratering flow fields, crates dynamics, determining impact conditions from total crater welt, centrifuge quarter-space cratering, and impact cratering mechanics research is documented.

Craters on comets

Science.gov (United States)

Vincent, J.; Oklay, N.; Marchi, S.; Höfner, S.; Sierks, H.

2014-07-01

This paper reviews the observations of crater-like features on cometary nuclei. ''Pits'' have been observed on almost all cometary nuclei but their origin is not fully understood [1,2,3,4]. It is currently assumed that they are created mainly by the cometary activity with a pocket of volatiles erupting under a dust crust, leaving a hole behind. There are, however, other features which cannot be explained in this way and are interpreted alternatively as remnants of impact craters. This work focusses on the second type of pit features: impact craters. We present an in-depth review of what has been observed previously and conclude that two main types of crater morphologies can be observed: ''pit-halo'' and ''sharp pit''. We extend this review by a series of analysis of impact craters on cometary nuclei through different approaches [5]: (1) Probability of impact: We discuss the chances that a Jupiter Family Comet like 9P/Tempel 1 or the target of Rosetta 67P/Churyumov-Gerasimenko can experience an impact, taking into account the most recent work on the size distribution of small objects in the asteroid Main Belt [6]. (2) Crater morphology from scaling laws: We present the status of scaling laws for impact craters on cometary nuclei [7] and discuss their strengths and limitations when modeling what happens when a rocky projectile hits a very porous material. (3) Numerical experiments: We extend the work on scaling laws by a series of hydrocode impact simulations, using the iSALE shock physics code [8,9,10] for varying surface porosity and impactor velocity (see Figure). (4) Surface processes and evolution: We discuss finally the fate of the projectile and the effects of the impact-induced surface compaction on the activity of the nucleus. To summarize, we find that comets do undergo impacts although the rapid evolution of the surface erases most of the features and make craters difficult to detect. In the case of a collision between a rocky body and a highly porous

Antarctic Meteorite Newsletter. Volume 22

Science.gov (United States)

Satterwhite, Cecilia (Editor); Lindstrom, Marilyn (Editor)

1999-01-01

This Newsletter Contains Classifications of 143 New Meteorites from the 1997 ANSMET Collection. Descriptions are given for 6 meteorites;2 eucrites, and 4 ordinary chondrites. We don't expect much excitement from the rest of the 1997 collection. JSC has examined another 100 meteorites to send to the Smithsonian for classification and they appear to be more of the same LL5 shower. However, past experience tells us that there will be some treasures hidden in the remaining samples. Hope rings eternal, but we can't wait to see the 1998 collection described below.

Meteorite Unit Models for Structural Properties

Science.gov (United States)

Agrawal, Parul; Carlozzi, Alexander A.; Karajeh, Zaid S.; Bryson, Kathryn L.

2017-10-01

To assess the threat posed by an asteroid entering Earth’s atmosphere, one must predict if, when, and how it fragments during entry. A comprehensive understanding of the asteroid material properties is needed to achieve this objective. At present, the meteorite material found on earth are the only objects from an entering asteroid that can be used as representative material and be tested inside a laboratory. Due to complex composition, it is challenging and expensive to obtain reliable material properties by means of laboratory test for a family of meteorites. In order to circumvent this challenge, meteorite unit models are developed to determine the effective material properties including Young’s modulus, compressive and tensile strengths and Poisson’s ratio, that in turn would help deduce the properties of asteroids. The meteorite unit model is a representative volume that accounts for diverse minerals, porosity, cracks and matrix composition.The Young’s Modulus and Poisson’s Ratio in the meteorite units are calculated by performing several hundreds of Monte Carlo simulations by randomly distributing the various phases inside these units. Once these values are obtained, cracks are introduced in these units. The size, orientation and distribution of cracks are derived by CT-scans and visual scans of various meteorites. Subsequently, simulations are performed to attain stress-strain relations, strength and effective modulus values in the presence of these cracks. The meteorite unit models are presented for H, L and LL ordinary chondrites, as well as for terrestrial basalt. In the case of the latter, data from the simulations is compared with experimental data to validate the methodology. These meteorite unit models will be subsequently used in fragmentation modeling of full scale asteroids.

Meteoritics, Number 19

Science.gov (United States)

1964-06-01

266, 1958. 131. Houziaux, L., Spectres d’absorption infra-rouge de quelques verres naturels entr 2 et 24 microns (Infrared Absorption Spectra of...Taking Pb20L’ 1), Given as a Function of Time. reteorites was made in a work by M. M. Shats (Ref. 10). M. M. Shats de - termined the uranium and lead...billion years. Table 6. Age, l09 Type of Data of Published Meteorite Years Meteorite Source, Investi- gator Kashin 3.00 Chondrite 1951 (Ref. 14), E.K

Iron and stony-iron meteorites

DEFF Research Database (Denmark)

Benedix, Gretchen K.; Haack, Henning; McCoy, T. J.

2014-01-01

Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar...... to that continuing on Earth – although on much smaller length- and timescales – with melting of the metal and silicates; differentiation into core, mantle, and crust; and probably extensive volcanism. Iron and stony-iron meteorites are our only available analogues to materials found in the deep interiors of Earth...

Internal Architecture of Meteorite Impact Crater at Bukit Bunuh, Lenggong – Perak, Malaysia Inferred from Upward Continuation of Magnetic Field Intensity Data

Science.gov (United States)

Muhammad, S. B.; Saad, R.; Saidin, M.; Yusoh, R.; Sabrian, T. A.; Samuel, Y. M.

2018-04-01

2–D upward continuation of magnetic field data acquired at Bukit Bunuh, Lenggong – Perak, Malaysia, with the objective to ascertain the impact crater and possible rebounds, has be carried out and interpreted in this study. Ground magnetic survey was conducted first as regional study in the entire area followed by a detailed study at the suspected crater region. Data from both studies were compiled, corrected and separated (regional – residual). The residual magnetic data ranged between -272 and +134.2 nT. 2–D upward continuation at various planes of observation was carried out on the gridded residual magnetic field data after coordinates were converted (from degrees to meters) to understate anomalies due to shallow features. The planes were at 250 m, 500 m and 750 m above the ground level. The continuation at 500 m revealed a low magnetic region, believed to be an impact crater, which is now filled with sediments, surrounded by a high magnetic shallow bedrock. Other high magnetic key features interpreted as rebounds (R) also remained after filtering out the ambiguous anomalies.

Evidence for rapid topographic evolution and crater degradation on Mercury from simple crater morphometry

Science.gov (United States)

Fassett, Caleb I.; Crowley, Malinda C.; Leight, Clarissa; Dyar, M. Darby; Minton, David A.; Hirabayashi, Masatoshi; Thomson, Bradley J.; Watters, Wesley A.

2017-06-01

Examining the topography of impact craters and their evolution with time is useful for assessing how fast planetary surfaces evolve. Here, new measurements of depth/diameter (d/D) ratios for 204 craters of 2.5 to 5 km in diameter superposed on Mercury's smooth plains are reported. The median d/D is 0.13, much lower than expected for newly formed simple craters ( 0.21). In comparison, lunar craters that postdate the maria are much less modified, and the median crater in the same size range has a d/D ratio that is nearly indistinguishable from the fresh value. This difference in crater degradation is remarkable given that Mercury's smooth plains and the lunar maria likely have ages that are comparable, if not identical. Applying a topographic diffusion model, these results imply that crater degradation is faster by a factor of approximately two on Mercury than on the Moon, suggesting more rapid landform evolution on Mercury at all scales.Plain Language SummaryMercury and the Moon are both airless bodies that have experienced numerous impact events over billions of years. These impacts form craters in a geologic instant. The question examined in this manuscript is how fast these craters erode after their formation. To simplify the problem, we examined craters of a particular size (2.5 to 5 km in diameter) on a particular geologic terrain type (volcanic smooth plains) on both the Moon and Mercury. We then measured the topography of hundreds of craters on both bodies that met these criteria. Our results suggest that craters on Mercury become shallower much more quickly than craters on the Moon. We estimate that Mercury's topography erodes at a rate at least a factor of two faster than the Moon's.

Martian Low-Aspect-Ratio Layered Ejecta (LARLE) craters: Distribution, characteristics, and relationship to pedestal craters

Science.gov (United States)

Barlow, Nadine G.; Boyce, Joseph M.; Cornwall, Carin

2014-09-01

Low-Aspect-Ratio Layered Ejecta (LARLE) craters are a unique landform found on Mars. LARLE craters are characterized by a crater and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which terminates in a sinuous, almost flame-like morphology. We have conducted a survey to identify all LARLE craters ⩾1-km-diameter within the ±75° latitude zone and to determine their morphologic and morphometric characteristics. The survey reveals 140 LARLE craters, with the majority (91%) located poleward of 40°S and 35°N and all occurring within thick mantles of fine-grained deposits which are likely ice-rich. LARLE craters range in diameter from the cut-off limit of 1 km up to 12.2 km, with 83% being smaller than 5 km. The radius of the outer LARLE deposit displays a linear trend with the crater radius and is greatest at higher polar latitudes. The LARLE deposit ranges in length between 2.56 and 14.81 crater radii in average extent, with maximum length extending up to 21.4 crater radii. The LARLE layer is very sinuous, with lobateness values ranging between 1.45 and 4.35. LARLE craters display a number of characteristics in common with pedestal craters and we propose that pedestal craters are eroded versions of LARLE craters. The distribution and characteristics of the LARLE craters lead us to propose that impact excavation into ice-rich fine-grained deposits produces a dusty base surge cloud (like those produced by explosion craters) that deposits dust and ice particles to create the LARLE layers. Salts emplaced by upward migration of water through the LARLE deposit produce a surficial duricrust layer which protects the deposit from immediate removal by eolian processes.

Thermoluminescence of meteorites and their orbits

Science.gov (United States)

Melcher, C. L.

1981-01-01

The thermoluminescence levels of 45 ordinary chondrites are measured in order to provide information on the orbital characteristics of the meteorites before impact. Glow curves of the photon emission response of powdered samples of the meteorites to temperatures up to 550 C in the natural state and following irradiation by a laboratory test dose of 110,000 rad were obtained as functions of terrestrial age and compared to those of samples of the Pribram, Lost City and Innisfree meteorites, for which accurate orbital data is available. The thermoluminescence levels in 40 out of 42 meteorites are found to be similar to those of the three control samples, indicating that the vast majority of ordinary chondrites that survive atmospheric entry have perihelia in the range 0.8-1 AU. Of the remaining two, Farmville is observed to exhibit an unusually large gradient in thermoluminescence levels with sample depth, which may be a result of a temperature gradient arising in a slowly rotating meteorite. Finally, the thermoluminescence measured in the Malakal meteorite is found to be two orders of magnitude lower than control samples, which is best explained by thermal draining by solar heating in an orbit with a perihelion distance of 0.5 to 0.6 AU.

Thermoluminescence of meteorites and their orbits

International Nuclear Information System (INIS)

Melcher, C.L.

1981-01-01

The thermolunimescence (TL) levels of 45 ordinary chondrites were measured to obtain information about the meteorite orbits. The low-temperature TL reaches equilibrium while the meteorite is in space and reflects the temperature of the meteorite at perihelion. Samples of Pribram, Lost City, and Innisfree, whose orbits are accurately known, were used as control samples. The TL levels in 40 out of 42 meteorites are similar to the three control samples, indicating that the vast majority of ordinary chondrites that survive atmospheric entry have perihelia similar to three known orbits, i.e., in the range 0.8-1 AU. The effects of albedo and rotation are also considered. A simple model indicates that temperature gradients of 1-2 0 K/cm are possible in slowly rotating meteoroids and such a temperature gradient is consistent with the unusually large TL gradient measured in the Farmville meteorite. Since slow rotation rates are improbable, other possibilities are examined but no satisfactory explanation has been found. The TL level measured in the Malakal meteorite is two orders of magnitude lower than control samples and is best explained by thermal draining due to solar heating in an orbit with a small perihelion distance. The perihelion is estimated to be approx. 0.5-0.6 AU. (orig.)

Cosmic-ray exposure records and origins of meteorites

International Nuclear Information System (INIS)

Reedy, R.C.

1985-01-01

The cosmic-ray records of meteorites are used to infer much about their origins and recent histories. The methods used to interpret meteorites cosmic-ray records, especially identifying simple or complex exposure histories, often are inadequate. Spallogenic radionuclides, stable nuclides, and measurements of products that have location-sensitive production rates, such as the tracks of heavy cosmic-ray nuclei or neutron-capture nuclides, are very useful in accurately determining a meteorite's history. Samples from different, known locations of a meteorite help in studying the cosmic-ray record. Such extensive sets of meteorite measuremetns, plus theoretical modeling of complex histories, improves the ability to predict the production of cosmogenic nuclides in meteorites, to distinguish simple and complex exposure histories, and to better determine exposure ages

Cosmic-ray exposure records and origins of meteorites

International Nuclear Information System (INIS)

Reedy, R.C.

1985-01-01

The cosmic-ray records of meteorites can be used to infer much about their origins and recent histories. Some meteorites had simple cosmic-ray exposure histories, while others had complex exposure histories with their cosmogenic products made both before and after a collision in space. The methods used to interpret meteorites' cosmic-ray records, especially identifying simple or complex exposure histories, often are inadequate. Besides spallogenic radionuclides and stable nuclides, measurements of products that have location-sensitive production rates, such as the tracks of heavy cosmic-ray nuclei or neutron-capture nuclides, are very useful in accurately determining a meteorite's history. Samples from different, known locations of a meteorite help in studying the cosmic-ray record. Such extensive sets of meteorite measurements, plus theoretical modeling of complex histories, will improve our ability to predict the production of cosmogenic nuclides in meteorites, to distinguish simple and complex exposure histories, and to better determine exposure ages

The Virtual Museum for Meteorites

Science.gov (United States)

Madiedo, J. M.

2012-09-01

Meteorites play a fundamental role in education and outreach, as these samples of extraterrestrial materials are very valuable tools to promote the public's interest in Astronomy and Planetary Sciences. Thus, for instance, meteorite exhibitions reveal the interest and fascination of students, educators and even researchers for these peculiar rocks and how these can provide information to explain many fundamental questions related to the origin and evolution of our Solar System. However, despite the efforts of private collectors, museums and other institutions to organize meteorite exhibitions, the reach of these is usually limited. But this issue can be addressed thanks to new technologies related to the Internet. In fact we can take advantage of HTML and related technologies to overcome local boundaries and open the possibility of offering these exhibitions for a global audience. With this aim a Virtual Museum for Meteorites has been created and a description of this web-based tool is given here.

Drainage systems of Lonar Crater, India: Contributions to Lonar Lake hydrology and crater degradation

Science.gov (United States)

Komatsu, Goro; Senthil Kumar, P.; Goto, Kazuhisa; Sekine, Yasuhito; Giri, Chaitanya; Matsui, Takafumi

2014-05-01

Lonar, a 1.8-km-diameter impact crater in India, is a rare example of terrestrial impact craters formed in basaltic bedrock. The estimated age of the crater ranges widely from less than 12 ka to over 600 ka, but the crater preserves a relatively pristine morphology. We conducted a study of various drainage systems of Lonar Crater. The crater floor hosts a shallow 5-m-deep lake, which fluctuates seasonally. Our investigation reveals that the lake level is influenced by surface runoff that is active during the monsoon and groundwater input effective during both the rainy and the dry seasons. The groundwater discharge is observed as springs on the inner rim walls corresponding to weathered vesicular basalt and/or proximal ejecta, which are underlain by thick massive basalt layers. This observation indicates that groundwater movement is lithologically controlled: it passes preferentially through permeable vesicular basalt or proximal ejecta but is hindered in less permeable massive basalt. It is hypothesized that groundwater is also structurally controlled by dipping of basalt layers, interconnectivity of the permeable lithologic units through fractures, and preferential pathways such as fractures within the permeable lithologic units. Investigation on hydrological processes at Lonar Crater and its lake could provide useful insights into purported paleo-crater lakes presumably formed in the basaltic crust of Mars. The Lonar Crater interior shows signs of degradation in the forms of gullies and debris flows, and the Dhar valley incising in the rim leading to form a fan delta. The ejecta surface is characterized by the presence of channels, originating from the rim area and extending radially away from the crater center. The channels probably resulted from surface runoff, and its erosion contributes to the removal of the ejecta. Lonar Crater is a valuable analog site for studying degradation processes with potential application to impact craters occurring on

Consortium study of lunar meteorites Yamato-793169 and Asuka-881757: Geochemical evidence of mutual similarity, and dissimilarity versus other mare basalts

Science.gov (United States)

Warren, Paul H.; Lindstrom, Marilyn M.

1993-01-01

Compositions of bulk powders and separated minerals from two meteorites derived from the mare lava plains of the Earth's Moon, Yamato-793169 and Asuka-881757, indicate a remarkable degree of similarity to one another, and clearly favor lunar origin. However, these meteorites are unlike any previously studied lunar rock. In both cases, the bulk-rock TiO2 content is slightly greater than the level separating VLT from low-Ti mare basalt, yet the Sc content is much higher than previously observed except among high-Ti mare basalts. Conceivably, the Sc enrichment in A881757 reflects origin of this rock as a cumulate from a mare magma of 'normal' Sc content, but this seems unlikely. Mineral-separate data suggest that most of the Sc is in pyroxene, and a variety of evidence weighs against the cumulus hypothesis as a major cause for the high Sc. The remarkable similarity between Y793169 and A881757 suggests the possibility that they were derived from a single source crater on the Moon.

Centrifuge Impact Cratering Experiments

Science.gov (United States)

Schmidt, R. M.; Housen, K. R.; Bjorkman, M. D.

1985-01-01

The kinematics of crater growth, impact induced target flow fields and the generation of impact melt were determined. The feasibility of using scaling relationships for impact melt and crater dimensions to determine impactor size and velocity was studied. It is concluded that a coupling parameter determines both the quantity of melt and the crater dimensions for impact velocities greater than 10km/s. As a result impactor radius, a, or velocity, U cannot be determined individually, but only as a product in the form of a coupling parameter, delta U micron. The melt volume and crater volume scaling relations were applied to Brent crater. The transport of melt and the validity of the melt volume scaling relations are examined.

Mercury's Densely Cratered Surface

Science.gov (United States)

1974-01-01

Mariner 10 took this picture (FDS 27465) of the densely cratered surface of Mercury when the spacecraft was 18,200 kilometers (8085 miles) from the planet on March 29. The dark line across top of picture is a 'dropout' of a few TV lines of data. At lower left, a portion of a 61 kilometer (38 mile) crater shows a flow front extending across the crater floor and filling more than half of the crater. The smaller, fresh crater at center is about 25 kilometers (15 miles) in diameter. Craters as small as one kilometer (about one-half mile) across are visible in the picture.The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.Image Credit: NASA/JPL/Northwestern University

Buried Craters of Utopia

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-365, 19 May 2003Beneath the northern plains of Mars are numerous buried meteor impact craters. One of the most heavily-cratered areas, although buried, occurs in Utopia Planitia, as shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. The history of Mars is complex; impact craters provide a tool by which to understand some of that history. In this case, a very ancient, cratered surface was thinly-buried by younger material that is not cratered at all. This area is near 48.1oN, 228.2oW; less than 180 km (112 mi) west of the Viking 2 lander site. Sunlight illuminates the scene from the lower left.

Moessbauer study of Slovak meteorites

Energy Technology Data Exchange (ETDEWEB)

Lipka, J.; Sitek, J.; Dekan, J., E-mail: julius.dekan@stuba.sk; Degmova, J. [Slovak University of Technology, Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology (Slovakia); Porubcan, V. [Comenius University, Faculty of Mathematics and Physics (Slovakia)

2013-04-15

{sup 57}Fe Moessbauer spectroscopy was used as an analytical tool in the investigation of iron containing compounds of two meteorites (Rumanova and Kosice) out of total of six which had fallen on Slovak territory. In the magnetic fraction of the iron bearing compounds in the Rumanova meteorite, maghemite, troilite and Fe-Ni alloy were identified. In the non-magnetic fraction silicate phases were found, such as olivine and pyroxene. The paramagnetic component containing Fe{sup 3 + } ions corresponds probably to small superparamagnetic particles. The Kosice meteorite was found near the town of Kosice in February 2010. Its magnetic fraction consists of a Fe-Ni alloy with the Moessbauer parameters of the magnetic field corresponding to kamacite {alpha}-Fe(Ni, Co) and troilite. The non-magnetic part consists of Fe{sup 2 + } phases such as olivine and pyroxene and traces of a Fe{sup 3 + } phase. The main difference between these meteorites is their iron oxide content. These kinds of analyses can bring important knowledge about phases and compounds formed in extraterrestrial conditions, which have other features than their terrestrial analogues.

Asteroid 2008 TC3 Breakup and Meteorite Fractions

Science.gov (United States)

Goodrich, C.; Jenniskens, P.; Shaddad, M. H.; Zolensky, M. E.; Fioretti, A. M.

2017-01-01

The recovery of meteorites from the impact of asteroid 2008 TC3 in the Nubian Desert of Sudan on October 7, 2008, marked the first time meteorites were collected from an asteroid observed in space by astronomical techniques before impacting. Search teams from the University of Khartoum traced the location of the strewn field and collected about 660 meteorites in four expeditions to the fall region, all of which have known fall coordinates. Upon further study, the Almahata Sitta meteorites proved to be a mixed bag of mostly ureilites (course grained, fine grained, and sulfide-metal assemblages), enstatite chondrites (EL3-6, EH3, EH5, breccias) and ordinary chondrites (H5-6, L4-5). One bencubbinite-like carbonaceous chondrite was identified, as well as one unique Rumuruti-like chondrite and an Enstatite achondrite. New analysis: The analysed meteorites so far suggest a high 30-40 percent fraction of non-ureilites among the recovered samples, but that high fraction does not appear to be in agreement with the meteorites in the University of Khartoum (UoK) collection. Ureilites dominate the meteorites that were recovered by the Sudanese teams. To better understand the fraction of recovered materials that fell to Earth, a program has been initiated to type the meteorites in the UoK collection in defined search areas. At this meeting, we will present some preliminary results from that investigation.

Meteorite and meteoroid: New comprehensive definitions

Science.gov (United States)

Rubin, A.E.; Grossman, J.N.

2010-01-01

Meteorites have traditionally been defined as solid objects that have fallen to Earth from space. This definition, however, is no longer adequate. In recent decades, man-made objects have fallen to Earth from space, meteorites have been identified on the Moon and Mars, and small interplanetary objects have impacted orbiting spacecraft. Taking these facts and other potential complications into consideration, we offer new comprehensive definitions of the terms "meteorite,""meteoroid," and their smaller counterparts: A meteoroid is a 10-??m to 1-m-size natural solid object moving in interplanetary space. A micrometeoroid is a meteoroid 10 ??m to 2 mm in size. A meteorite is a natural, solid object larger than 10 ??m in size, derived from a celestial body, that was transported by natural means from the body on which it formed to a region outside the dominant gravitational influence of that body and that later collided with a natural or artificial body larger than itself (even if it is the same body from which it was launched). Weathering and other secondary processes do not affect an object's status as a meteorite as long as something recognizable remains of its original minerals or structure. An object loses its status as a meteorite if it is incorporated into a larger rock that becomes a meteorite itself. A micrometeorite is a meteorite between 10 ??m and 2 mm in size. Meteorite- "a solid substance or body falling from the high regions of the atmosphere" (Craig 1849); "[a] mass of stone and iron that ha[s] been directly observed to have fallen down to the Earth's surface" (translated from Cohen 1894); "[a] solid bod[y] which came to the earth from space" (Farrington 1915); "A mass of solid matter, too small to be considered an asteroid; either traveling through space as an unattached unit, or having landed on the earth and still retaining its identity" (Nininger 1933); "[a meteoroid] which has reached the surface of the Earth without being vaporized" (1958

Size-Frequency Distribution of Small Lunar Craters: Widening with Degradation and Crater Lifetime

Science.gov (United States)

Ivanov, B. A.

2018-01-01

The review and new measurements are presented for depth/diameter ratio and slope angle evolution during small ( D model. The uncertainty of crater retention age due to crater degradational widening is estimated. The collected and analyzed data are discussed to be used in the future updating of mechanical models for lunar crater aging.

Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale Crater, Mars

Science.gov (United States)

Ming, D. W.; Archer, P. D.; Glavin, D. P.; Eigenbrode, J. L.; Franz, H. B.; Sutter, B.; Brunner, A. E.; Stern, J. C.; Freissinet, C.; McAdam, A. C.; Mahaffy, P. R.; Cabane, M.; Coll, P.; Campbell, J. L.; Atreya, S. K.; Niles, P. B.; Bell, J. F.; Bish, D. L.; Brinckerhoff, W. B.; Buch, A.; Conrad, P. G.; Des Marais, D. J.; Ehlmann, B. L.; Fairén, A. G.; Farley, K.; Flesch, G. J.; Francois, P.; Gellert, R.; Grant, J. A.; Grotzinger, J. P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J. A.; Leshin, L. A.; Lewis, K. W.; McLennan, S. M.; Miller, K. E.; Moersch, J.; Morris, R. V.; Navarro-González, R.; Pavlov, A. A.; Perrett, G. M.; Pradler, I.; Squyres, S. W.; Summons, R. E.; Steele, A.; Stolper, E. M.; Sumner, D. Y.; Szopa, C.; Teinturier, S.; Trainer, M. G.; Treiman, A. H.; Vaniman, D. T.; Vasavada, A. R.; Webster, C. R.; Wray, J. J.; Yingst, R. A.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Edgar, Lauren; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Blank, Jennifer; Weigle, Gerald; Schmidt, Mariek; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Ehlmann, Bethany; Griffes, Jennifer; Newcombe, Megan; Pilorget, Cedric; Rice, Melissa; Siebach, Kirsten; Stack, Katie; Brunet, Claude; Hipkin, Victoria; Léveillé, Richard; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Hayes, Alexander; Joseph, Jonathan; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Cécile; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Forni, Olivier; Gasnault, Olivier; Lasue, Jérémie; Lee, Qiu-Mei; Maurice, Sylvestre; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Coscia, David; Israël, Guy; Dromart, Gilles; Robert, François; Sautter, Violaine; Le Mouélic, Stéphane; Mangold, Nicolas; Nachon, Marion; Stalport, Fabien; Raulin, François; Cameron, James; Clegg, Sam; Cousin, Agnès; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Wiens, Roger C.; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Dyar, M. Darby; Fassett, Caleb; Blake, David F.; Bristow, Thomas; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Choi, David; Dworkin, Jason P.; Floyd, Melissa; Garvin, James; Harpold, Daniel; Jones, Andrea; Martin, David K.; Raaen, Eric; Smith, Michael D.; Tan, Florence; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Blaney, Diana; Brinza, David; Calef, Fred; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Feldman, Jason; Feldman, Sabrina; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Yen, Albert; Cucinotta, Francis; Jones, John H.; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Williams, Rebecca M. E.; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Clark, Benton; Wolff, Michael; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Schwenzer, Susanne P.; Anderson, Ryan B.; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; VanBommel, Scott; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; Bridges, John C.; McConnochie, Timothy; Benna, Mehdi; Bower, Hannah; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Gordon, Suzanne; Newsom, Horton; Ollila, Ann; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

2014-01-01

H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

Volatile and organic compositions of sedimentary rocks in Yellowknife Bay, Gale crater, Mars

Science.gov (United States)

Ming, D. W.; Archer, P.D.; Glavin, D.P.; Eigenbrode, J.L.; Franz, H.B.; Sutter, B.; Brunner, A.E.; Stern, J.C.; Freissinet, C.; McAdam, A.C.; Mahaffy, P.R.; Cabane, M.; Coll, P.; Campbell, J.L.; Atreya, S.K.; Niles, P.B.; Bell, J.F.; Bish, D.L.; Brinckerhoff, W.B.; Buch, A.; Conrad, P.G.; Des Marais, D.J.; Ehlmann, B.L.; Fairén, A.G.; Farley, K.; Flesch, G.J.; Francois, P.; Gellert, Ralf; Grant, J. A.; Grotzinger, J.P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J.A.; Leshin, L.A.; Lewis, K.W.; McLennan, S.M.; Miller, Karl E.; Moersch, J.; Morris, R.V.; Navarro- González, R.; Pavlov, A.A.; Perrett, G.M.; Pradler, I.; Squyres, S. W.; Summons, Roger E.; Steele, A.; Stolper, E.M.; Sumner, D.Y.; Szopa, C.; Teinturier, S.; Trainer, M.G.; Treiman, A.H.; Vaniman, D.T.; Vasavada, A.R.; Webster, C.R.; Wray, J.J.; Yingst, R.A.

2014-01-01

H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

Volatile and organic compositions of sedimentary rocks in Yellowknife Bay, Gale crater, Mars.

Science.gov (United States)

Ming, D W; Archer, P D; Glavin, D P; Eigenbrode, J L; Franz, H B; Sutter, B; Brunner, A E; Stern, J C; Freissinet, C; McAdam, A C; Mahaffy, P R; Cabane, M; Coll, P; Campbell, J L; Atreya, S K; Niles, P B; Bell, J F; Bish, D L; Brinckerhoff, W B; Buch, A; Conrad, P G; Des Marais, D J; Ehlmann, B L; Fairén, A G; Farley, K; Flesch, G J; Francois, P; Gellert, R; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; Leshin, L A; Lewis, K W; McLennan, S M; Miller, K E; Moersch, J; Morris, R V; Navarro-González, R; Pavlov, A A; Perrett, G M; Pradler, I; Squyres, S W; Summons, R E; Steele, A; Stolper, E M; Sumner, D Y; Szopa, C; Teinturier, S; Trainer, M G; Treiman, A H; Vaniman, D T; Vasavada, A R; Webster, C R; Wray, J J; Yingst, R A

2014-01-24

H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

Life on Mars: Evidence from Martian Meteorites

Science.gov (United States)

McKay, David S.; Thomas-Keptra, Katie L.; Clemett, Simon J.; Gibson, Everett K., Jr.; Spencer, Lauren; Wentworth, Susan J.

2009-01-01

New data on martian meteorite 84001 as well as new experimental studies show that thermal or shock decomposition of carbonate, the leading alternative non-biologic explanation for the unusual nanophase magnetite found in this meteorite, cannot explain the chemistry of the actual martian magnetites. This leaves the biogenic explanation as the only remaining viable hypothesis for the origin of these unique magnetites. Additional data from two other martian meteorites show a suite of biomorphs which are nearly identical between meteorites recovered from two widely different terrestrial environments (Egyptian Nile bottomlands and Antarctic ice sheets). This similarity argues against terrestrial processes as the cause of these biomorphs and supports an origin on Mars for these features.

Modeling the Thermal Interactions of Meteorites Below the Antarctic Ice

Science.gov (United States)

Oldroyd, William Jared; Radebaugh, Jani; Stephens, Denise C.; Lorenz, Ralph; Harvey, Ralph; Karner, James

2017-10-01

Meteorites with high specific gravities, such as irons, appear to be underrepresented in Antarctic collections over the last 40 years. This underrepresentation is in comparison with observed meteorite falls, which are believed to represent the actual population of meteorites striking Earth. Meteorites on the Antarctic ice sheet absorb solar flux, possibly leading to downward tunneling into the ice, though observations of this in action are very limited. This descent is counteracted by ice sheet flow supporting the meteorites coupled with ablation near mountain margins, which helps to force meteorites towards the surface. Meteorites that both absorb adequate thermal energy and are sufficiently dense may instead reach a shallow equilibrium depth as downward melting overcomes upward forces during the Antarctic summer. Using a pyronometer, we have measured the incoming solar flux at multiple depths in two deep field sites in Antarctica, the Miller Range and Elephant Moraine. We compare these data with laboratory analogues and model the thermal and physical interactions between a variety of meteorites and their surroundings. Our Matlab code model will account for a wide range of parameters used to characterize meteorites in an Antarctic environment. We will present the results of our model along with depth estimates for several types of meteorites. The recovery of an additional population of heavy meteorites would increase our knowledge of the formation and composition of the solar system.

Ernst Julius Öpik's (1916) note on the theory of explosion cratering on the Moon's surface—The complex case of a long-overlooked benchmark paper

Science.gov (United States)

Racki, Grzegorz; Koeberl, Christian; Viik, Tõnu; Jagt-Yazykova, Elena A.; Jagt, John W. M.

2014-10-01

High-velocity impact as a common phenomenon in planetary evolution was ignored until well into the twentieth century, mostly because of inadequate understanding of cratering processes. An eight-page note, published in Russian by the young Ernst Julius Öpik, a great Estonian astronomer, was among the key selenological papers, but due to the language barrier, it was barely known and mostly incorrectly cited. This particular paper is here intended to serve as an explanatory supplement to an English translation of Öpik's article, but also to document an early stage in our understanding of cratering. First, we outline the historical-biographical background of this benchmark paper, and second, a comprehensive discussion of its merits is presented, from past and present perspectives alike. In his theoretical research, Öpik analyzed the explosive formation of craters numerically, albeit in a very simple way. For the first time, he approximated relationships among minimal meteorite size, impact energy, and crater diameter; this scaling focused solely on the gravitational energy of excavating the crater (a "useful" working approach). This initial physical model, with a rational mechanical basis, was developed in a series of papers up to 1961. Öpik should certainly be viewed as the founder of the numerical simulation approach in planetary sciences. In addition, the present note also briefly describes Nikolai A. Morozov as a remarkable man, a forgotten Russian scientist and, surprisingly, the true initiator of Öpik's explosive impact theory. In fact, already between 1909 and 1911, Morozov probably was the first to consider conclusively that explosion craters would be circular, bowl-shaped depressions even when formed under different impact angles.

A model for the dynamics of crater-centered intrusion: Application to lunar floor-fractured craters

Science.gov (United States)

Thorey, Clément; Michaut, Chloé

2014-01-01

Lunar floor-fractured craters are a class of craters modified by post-impact mechanisms. They are defined by distinctive shallow floors that are convex or plate-like, sometimes with a wide floor moat bordering the wall region. Radial, concentric, and polygonal floor fractures suggest an endogenous process of modification. Two mechanisms have been proposed to account for such deformations: viscous relaxation and spreading of a magma intrusion at depth below the crater. To test the second assumption and bring more constraints on the intrusion process, we develop a model for the dynamics of magma spreading below an elastic overlying layer with a crater-like topography. As predicted in earlier more qualitative studies, the increase in lithostatic pressure at the crater wall zone prevents the intrusion from spreading laterally, leading to the thickening of the intrusion. Additionally, our model shows that the final crater floor appearance after the uplift, which can be convex or flat, with or without a circular moat bordering the wall zone, depends on the elastic thickness of the layer overlying the intrusion and on the crater size. Our model provides a simple formula to derive the elastic thickness of the overlying layer hence a minimum estimate for the intrusion depth. Finally, our model suggests that crust redistribution by cratering must have controlled magma ascent below most of these craters.

The Okhansk Meteorite: Specifics of Composition, Structure, and Genesis

Directory of Open Access Journals (Sweden)

A.I. Bakhtin

2016-12-01

Full Text Available The Okhansk meteorite fell on August 18, 1887 near the village of Tabor, about 15 km away from the town of Okhansk in Perm province and weighed 186.5 kg (the total weight of collected fragments, according to P.I. Krotov, was more than 245 kg. The shock wave from the meteorite entry knocked down animals and riders on horses. Despite the fact that it was significantly stronger than that caused by the Chelyabinsk meteorite of 2013, all information about this meteorite has completely erased from people's memory. It has been shown that the meteorite is an ordinary olivine-bronzite chondrite. Its main silicate minerals are olivine, bronzite, plagioclase, and diopside. The main ore minerals are kamacite and troilite. The meteorite contains silicate glass in large amounts. The analysis of the composition and structure of the Okhansk meteorite has demonstrated that it was formed at the early stages of accretion of the melted substance of the protosolar nebula without undergoing endogenous, temperature, or pressure changes.

Worlds beyond meteorite studies

International Nuclear Information System (INIS)

Lipschutz, M.E.

1986-01-01

Meteorites are of essential interest because they contain the oldest Solar System materials available for research and sample a wide range of parent bodies - exteriors and interiors - some primitive, some highly evolved. Meteorites carry decipherable records of certain solar and galactic effects and yield otherwise unobtainable data about the genesis, evolution, and composition of the Earth and other major planets, satellites, asteroids, and the Sun. Some contain inclusions tracing events from before the Solar System formed; others contain organic matter derived from giant molecular clouds in the interstellar medium. It is especially advantageous that meteorites occur on the Earth's surface, where the full spectrum of laboratory analytical techniques can be applied, ranging from the simplest to the most sophisticated. As the recently released report of the US National Commission on Space put it: If one picture is worth 10,000 words, then one sample is worth 10,000 pictures. Because of the interdisciplinary nature of meteorite studies - overlapping chemistry, physics, geology, and astronomy - no brief article can summarize the full scope of current research. After introducing some basic cosmochemical facts and approaches, this report will illustrate the nature of questions that cosmochemists ask and how they go about answering them. For reasons to be described, the author focuses on certain trace elements - especially Ag, Au, Bi, Cd, Co, Cs, In, Rb, Se, Te, Tl, and Zn - that are particularly responsive to relatively low temperature processes and that yield important genetic information

Crater in Utopia

Science.gov (United States)

2004-01-01

23 March 2004 Craters of the martian northern plains tend to be somewhat shallow because material has filled them in. Their ejecta blankets, too, are often covered by younger materials. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example--a crater in Utopia Planitia near 43.7oN, 227.3oW. Erosion has roughened some of the surfaces of the material that filled the crater and covered its ejecta deposit. The picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

Elemental composition analysis of stony meteorites discovered in Phitsanulok, Thailand

Science.gov (United States)

Loylip, T.; Wannawichian, S.

2017-09-01

A meteorite is a fragment of pure stone, iron or the mixture of stony-iron. The falling of meteorites into Earth’s surface is part of Earth’s accretion process from dust and rocks in our solar system. When these fragments come close enough to the Earth to be attracted by its gravity, they may fall into the Earth. Following the detection of objects that fall from the sky onto a home in Phitsanulok in June 27, the meteorites were analyzed by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS) instruments. The results from SEM/EDS analysis show that the meteorites are mainly composed of Fe-Ni and Fe-s. The meteorite is Achondrite, a class of meteorite which does not contain Chondrule. The meteorites in this work are thought to be part of a large asteroid.

PIXE and light element analysis (C,N) in glass inclusions trapped in meteorites with the nuclear microprobe

International Nuclear Information System (INIS)

Varela, M.E.; Mosbah, M.; Metrich, N.; Duraud, J.P.; Kurat, G.

1999-01-01

Proton-induced X-ray emission (PIXE) and light element analysis have been performed with the nuclear microprobe at the Laboratoire Pierre Suee (Saclay-France) in glass inclusions of the carbonaceous chondrites: Allende, Kaba and Renazzo, and in the achondrite meteorite: Chassigny. Carbon contents in olivine of chondrules are below the nuclear reactions analysis (NRA) detection limit, however, glasses from glass inclusions hosted by these grains, contain an appreciable and highly variable quantities of carbon (200-1600 ppm). This could indicate variable amounts of C trapped during glass inclusion formation. On the other hand, nitrogen is present in highly variable amounts in glasses of both, chondrites and achondrites minerals. Its abundance, correlated with depth from the section surface which suggests loss of N during analyses and therefore the possible existence of a very mobile (volatile?) species. A chondritic Rb/Sr and K/Rb ratio obtained by PIXE analyses in the glass-bearing inclusions of the Chassigny meteorite points towards a primitive source for the glass precursor of Chassigny inclusions

Indigenous Amino Acids in Iron Meteorites

Science.gov (United States)

Elsila, J. E.; Dworkin, J. P.; Glavin, D. P.; Johnson, N. M.

2018-01-01

Understanding the organic content of meteorites and the potential delivery of molecules relevant to the origin of life on Earth is an important area of study in astrobiology. There have been many studies of meteoritic organics, with much focus on amino acids as monomers of proteins and enzymes essential to terrestrial life. The majority of these studies have involved analysis of carbonaceous chondrites, primitive meteorites containing approx. 3-5 wt% carbon. Amino acids have been observed in varying abundances and distributions in representatives of all eight carbonaceous chondrite groups, as well as in ungrouped carbonaceous chondrites, ordinary and R chondrites, ureilites, and planetary achondrites [1 and references therein].

Enantiomer Ratios of Meteoritic Sugar Derivatives

Science.gov (United States)

Cooper, George

2012-01-01

Carbonaceous meteorites contain a diverse suite of soluble organic compounds. Studies of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in meteorites are keto acids (pyruvic acid, etc.), hydroxy tricarboxylic acids (1), amino acids, amides, purines and pyrimidines. The Murchison and Murray meteorites are the most studied for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) meteoritic compounds are racemic, (i.e., their D/L enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino acids contain slightly more of one enantiomer (usually the L) than the other. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) meteoritic sugar acids. The molecular and enantiomer analysis of corresponding sugar alcohols will also be discussed. Detailed analytical procedures for sugar-acid enantiomers have been described. Results of several meteorite analyses show that glyceric acid is consistently racemic (or nearly so) as expected of non-biological mechanisms of synthesis. Also racemic are 4-C deoxy sugar acids: 2-methyl glyceric acid; 2,4-dihydroxybutyric acid; 2,3-dihydroxybutyric acid (two diastereomers); and 3,4-dihydroxybutyric acid. However, a 4C acid, threonic acid, has never been observed as racemic, i.e., it possesses a large D excess. In several samples of Murchison and one of GRA 95229 (possibly the most pristine carbonaceous meteorite yet analyzed) threonic acid has nearly the same D enrichment. In Murchison, preliminary isotopic measurements of individual threonic acid enantiomers point towards extraterrestrial sources of the D enrichment. Enantiomer analyses of the 5C mono-sugar acids, ribonic, arabinonic, xylonic, and lyxonic also show large D excesses. It is worth noting that all four of these acids (all of the possible straight-chained 5C sugar acids) are present in meteorites, including the

Chiral Biomarkers in Meteorites

Science.gov (United States)

Hoover, Richard B.

2010-01-01

The chirality of organic molecules with the asymmetric location of group radicals was discovered in 1848 by Louis Pasteur during his investigations of the rotation of the plane of polarization of light by crystals of sodium ammonium paratartrate. It is well established that the amino acids in proteins are exclusively Levorotary (L-aminos) and the sugars in DNA and RNA are Dextrorotary (D-sugars). This phenomenon of homochirality of biological polymers is a fundamental property of all life known on Earth. Furthermore, abiotic production mechanisms typically yield recemic mixtures (i.e. equal amounts of the two enantiomers). When amino acids were first detected in carbonaceous meteorites, it was concluded that they were racemates. This conclusion was taken as evidence that they were extraterrestrial and produced by abiologically. Subsequent studies by numerous researchers have revealed that many of the amino acids in carbonaceous meteorites exhibit a significant L-excess. The observed chirality is much greater than that produced by any currently known abiotic processes (e.g. Linearly polarized light from neutron stars; Circularly polarized ultraviolet light from faint stars; optically active quartz powders; inclusion polymerization in clay minerals; Vester-Ulbricht hypothesis of parity violations, etc.). This paper compares the measured chirality detected in the amino acids of carbonaceous meteorites with the effect of these diverse abiotic processes. IT is concluded that the levels observed are inconsistent with post-arrival biological contamination or with any of the currently known abiotic production mechanisms. However, they are consistent with ancient biological processes on the meteorite parent body. This paper will consider these chiral biomarkers in view of the detection of possible microfossils found in the Orgueil and Murchison carbonaceous meteorites. Energy dispersive x-ray spectroscopy (EDS) data obtained on these morphological biomarkers will be

Historical Romanian meteorites: emendations of official catalogue records

Directory of Open Access Journals (Sweden)

Dana Lüttge-Pop

2013-12-01

Full Text Available With its more than 50,000 valid official and provisory meteorite entries, the online catalogue of The Meteoritical Society, i.e., the Meteoritical Bulletin Database (MBDB represents the most authorized and primary source of information in the field. Unfortunately, this official reference contains some erroneous geographical information in the case of five historical Romanian meteorites. For Zsadany, the current country information is “Hungary, Bekes county” instead of Romania, Timiş County. For Mezö-Madaras and Tauti, the county affiliations “Harghita” and respectively “Cluj” have to be corrected into Mureş and Arad, respectively. Geographical coordinates for Kakowa and Ohaba require minor corrections, only. The source of these errors resides in changes of names and administrative affiliations of the localities of the fall/find, while the formal nomenclature protocol requires the meteorite name in the original description to be preserved. The example of the historical Romanian meteorites illustrates the challenges that a researcher unfamiliar with a region faces when locating old specimens, in general. This requires knowledge of regional history and geography, and sometimes access to the original references - usually not written in English, or having a somehow limited circulation. Additionally, in the last two decades several new publications provided more detailed classification information on Sopot, Ohaba, Tauti and Mocs meteorites. Sopot was classified as H5, with shock stage S3. The studied Ohaba and Tauti samples also attested S3 shock stages. Variable shock stages (S3-5 were identified in Mocs samples, the most well-known Romanian meteorite. This new information should be added to the corresponding MBDB entries.

Obtaining Magnetic Properties of Meteorites Using Magnetic Scanner

Science.gov (United States)

Kletetschka, G.; Nabelek, L.; Mazanec, M.; Simon, K.; Hruba, J.

2015-12-01

Magnetic images of Murchison meteorite's and Chelyabinsk meteorite's thin section have been obtained from magnetic scanning system from Youngwood Science and Engineering (YSE) capable of resolving magnetic anomalies down to 10-3 mT range from about 0.3 mm distance between the probe and meteorite surface (resolution about 0.15 mm). Anomalies were produced repeatedly, each time after application of magnetic field pulse of varying amplitude and constant, normal or reversed, direction. This process resulted in both magnetizing and demagnetizing of the meteorite thin section, while keeping the magnetization vector in the plane of the thin section. Analysis of the magnetic data allows determination of coercivity of remanence (Bcr) for the magnetic sources in situ. Value of Bcr is critical for calculating magnetic forces applicable during missions to asteroids where gravity is compromised. Bcr was estimated by two methods. First method measured varying dipole magnetic field strength produced by each anomaly in the direction of magnetic pulses. Second method measured deflections of the dipole direction from the direction of magnetic pulses (Nabelek et al., 2015). Nabelek, L., Mazanec, M., Kdyr, S., and Kletetschka, G., 2015, Magnetic, in situ, mineral characterization of Chelyabinsk meteorite thin section: Meteoritics & Planetary Science.

Extraterrestrial Organic Compounds in Meteorites

Science.gov (United States)

Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

2003-01-01

Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

Crater Degradation on Mercury: A Global Perspective

Science.gov (United States)

Kinczyk, M. J.; Byrne, P. K.; Prockter, L. M.; Susorney, H. C. M.; Chapman, C. R.; Barnouin, O. S.

2017-12-01

On geologic timescales, initially fresh craters are subjected to many weathering mechanisms. Whereas water and wind are, or were, effective erosive mechanisms such as on Earth and Mars, micrometeorite bombardment and modification due to subsequent impacts are the dominant processes that degrade craters and crater rays on airless bodies like the Moon and Mercury. Classifying craters based on their state of degradation can help determine the relative ages of landforms proximal to, and crosscut by, these craters. However, this method is most effective when used together with statistical analysis of crater distributions. Pre-MESSENGER degradation classification schemes lacked sufficient detail to be consistently applied to craters of various sizes and morphological types—despite evidence suggesting that the ejecta deposits of large basins persist much longer than those of smaller craters, for instance—yet broad assumptions have been made regarding the correlation of crater class to the planet's time-stratigraphic sequence. Moreover, previous efforts to categorize craters by degradation state have either been restricted to regional study sites or applied only to a subset of crater age or size. As a result, numerous interpretations of crater degradation state persist for Mercury, challenging a complete understanding of this process on the innermost planet. We report on the first global survey of crater degradation on Mercury. By modifying an established 5-class scheme, we have systematically applied a rigorous set of criteria to all craters ≥40 km in diameter on the planet. These criteria include the state and morphology of crater deposits separately (e.g., rim, floor, wall, ejecta) and degradation classes were assigned as the collection of these individual attributes. This approach yields a consistent classification of craters of different sizes. Our results provide the first comprehensive assessment of how craters of various states of degradation are distributed

Tracing meteorite source regions through asteroid spectroscopy

Science.gov (United States)

Thomas, Cristina Ana

By virtue of their landing on Earth, meteorites reside in near-Earth object (NEO) orbits prior to their arrival. Thus the population of observable NEOs, in principle, gives the best representation of meteorite source bodies. By linking meteorites to NEOs, and linking NEOs to their most likely main-belt source locations, we seek to gain insight into the original solar system formation locations for different meteorite classes. To forge the first link between meteorites and NEOs, we have developed a three dimensional method for quantitative comparisons between laboratory measurements of meteorites and telescopic measurements of near-Earth objects. We utilize meteorite spectra from the Reflectance Experiment Laboratory (RELAB) database and NEO data from the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). Using the Modified Gaussian Model (MGM) as a mathematical tool, we treat asteroid and meteorite spectra identically in the calculation of 1-micron and 2-micron geometric band centers and their band area ratios (BARs). Using these identical numerical parameters we quantitatively compare the spectral properties of S-, Sq-, Q- and V-type NEOs with the spectral properties of the meteorites in the H, L, LL and HED meteorite classes. For each NEO spectrum, we assign a set of probabilities for it being related to each of these meteorite classes. Our NEO- meteorite correlation probabilities are then convolved with NEO-source region probabilities to yield a final set of meteorite-source region correlations. An apparent (significant at the 2.1-sigma level) source region signature is found for the H chondrites to be preferentially delivered to the inner solar system through the 3:1 mean motion resonance. A 3:1 resonance H chondrite source region is consistent with the short cosmic ray exposure ages known for H chondrites. The spectroscopy of asteroids is subject to several sources of inherent error. The source region model used a variety of S-type spectra without

Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories

Science.gov (United States)

Elsila, Jamie E.; Aponte, Jose C.; Blackmond, Donna G.; Burton, Aaron S.; Dworkin, Jason P.; Glavin, Daniel P.

2016-01-01

The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplied by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large -enantiomeric excesses of some extraterrestrial protein amino acids (up to 60) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work.

The Chicxulub Multiring Impact Crater and the Cretaceous/Paleogene Boundary: Results From Geophysical Surveys and Drilling

Science.gov (United States)

Urrutia-Fucugauchi, J.; Perez-Cruz, Ligia

2010-03-01

The Chicxulub crater has attracted considerable attention as one of the three largest terrestrial impact structures and its association with the Cretaceous/Paleogene boundary (K/Pg). Chicxulub is a 200 km-diameter multi-ring structure formed 65.5 Ma ago in the Yucatan carbonate platform in the southern Gulf of Mexico and which has since been buried by Paleogene and Neogene carbonates. Chicxulub is one of few large craters with preserved ejecta deposits, which include the world-wide K/Pg boundary clay layer. The impact has been related to the global major environmental and climatic effects and the organism mass extinction that mark the K/Pg boundary, which affected more than 70 % of organisms, including the dinosaurs, marine and flying reptiles, ammonites and a large part of the marine microorganisms. The impact and crater formation occur instantaneously, with excavation of the crust down to 25 km depths in fractions of second and lower crust uplift and crater formation in a few hundreds of seconds. Energy released by impact and crustal deformation generates seismic waves traveling the whole Earth, and resulting in intense fracturing and deformation at the target site. Understanding of the physics of impacts on planetary surfaces and modeling of processes of crustal deformation, rheological behavior of materials at high temperatures and pressures remain a major challenge in geosciences. Study of the Chicxulub crater and the global effects and mass extinction requires inter- and multidisciplinary approaches, with researchers from many diverse fields beyond the geosciences. With no surface exposures, geophysical surveys and drilling are required to study the crater. Differential compaction between the impact breccias and the surrounding carbonate rocks has produced a ring-fracture structure that at the surface reflects in a small topographic depression and the karstic cenote ring. The crater structure, located half offshore and half on-land, has been imaged by

A Tale of 3 Craters

Science.gov (United States)

2004-01-01

11 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures some of the complexity of the martian upper crust. Mars does not simply have an impact-cratered surface, it's upper crust is a cratered volume. Over time, older craters on Mars have been eroded, filled, buried, and in some cases exhumed and re-exposed at the martian surface. The crust of Mars is layered to depths of 10 or more kilometers, and mixed in with the layered bedrock are a variety of ancient craters with diameters ranging from a few tens of meters (a few tens of yards) to several hundred kilometers (more than one or two hundred miles). The picture shown here captures some of the essence of the layered, cratered volume of the upper crust of Mars in a very simple form. The image shows three distinct circular features. The smallest, in the lower right quarter of the image, is a meteor crater surrounded by a mound of material. This small crater formed within a layer of bedrock that once covered the entire scene, but today is found only in this small remnant adjacent to the crater. The intermediate-sized crater, west (left) of the small one, formed either in the next layer down--that is, below the layer in which the small crater formed--or it formed in some layers that are now removed, but was big enough to penetrate deeply into the rock that is near the surface today. The largest circular feature in the image, in the upper right quarter of the image, is still largely buried. It formed in layers of rock that are below the present surface. Erosion has brought traces of its rim back to the surface of Mars. This picture is located near 50.0oS, 77.8oW, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this October 2004 image from the upper left.

Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers

Directory of Open Access Journals (Sweden)

Alastair W. Tait

2017-06-01

Full Text Available Finding fresh, sterilized rocks provides ecologists with a clean slate to test ideas about first colonization and the evolution of soils de novo. Lava has been used previously in first colonizer studies due to the sterilizing heat required for its formation. However, fresh lava typically falls upon older volcanic successions of similar chemistry and modal mineral abundance. Given enough time, this results in the development of similar microbial communities in the newly erupted lava due to a lack of contrast between the new and old substrates. Meteorites, which are sterile when they fall to Earth, provide such contrast because their reduced and mafic chemistry commonly differs to the surfaces on which they land; thus allowing investigation of how community membership and structure respond to this new substrate over time. We conducted 16S rRNA gene analysis on meteorites and soil from the Nullarbor Plain, Australia. We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite. Despite the meteorites being found kilometers apart, the community structure of each meteorite bore more similarity to those of other meteorites (of similar composition than to the community structure of the soil on which it resided. Meteorites were dominated by sequences that affiliated with the Actinobacteria with the major Operational Taxonomic Unit (OTU classified as Rubrobacter radiotolerans. Proteobacteria and Bacteroidetes were the next most abundant phyla. The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites. We also found OTUs affiliated with iron/sulfur cycling organisms Geobacter spp. and Desulfovibrio spp. This is an important finding as meteorites contain abundant metal and sulfur for use as energy sources. These ecological findings demonstrate that the structure of the microbial community in these meteorites is controlled by the substrate, and will not

Stability of nuclear crater slopes in rock

International Nuclear Information System (INIS)

Fleming, Robert W.; Frandsen, Alton D.; LaFrenz, Robert L.

1970-01-01

The United States Army Engineer Nuclear Cratering Group was established in 1962 to participate with the Atomic Energy Commission in a joint research and development program to develop nuclear engineering and construction technology. A major part of this research effort has been devoted to studies of the engineering properties of craters. The program to date has included field investigations of crater properties in various media over a broad range of chemical and nuclear explosive yields, studies of man-made and natural slopes, and studies directed toward the development of analytical and empirical methods of crater stability analysis. From this background, a general understanding has been developed of the effects of a cratering explosion on the surrounding medium and of physical nature of the various crater zones which are produced. The stability of nuclear crater slopes has been a subject of prime interest in the feasibility study being conducted for an Atlantic-Pacific sea-level canal. Based on experimental evidence assembled to date, nuclear crater slopes in dry dock and dry alluvium have an initially stable configuration. There have been five nuclear craters produced to date with yields of 0.4 kt or more on which observations are based and the initial configurations of these craters have remained stable for over seven years. The medium, yield, crater dimensions, and date of event for these craters are summarized. It is interesting to note that the Sedan Crater has been subjected to strong seismic motions from nearby detonations without adverse effects

Stability of nuclear crater slopes in rock

Energy Technology Data Exchange (ETDEWEB)

Fleming, Robert W; Frandsen, Alton D; LaFrenz, Robert L [U.S. Army Engineer Nuclear Cratering Group, Lawrence Radiation Laboratory, Livermore, CA (United States)

1970-05-15

The United States Army Engineer Nuclear Cratering Group was established in 1962 to participate with the Atomic Energy Commission in a joint research and development program to develop nuclear engineering and construction technology. A major part of this research effort has been devoted to studies of the engineering properties of craters. The program to date has included field investigations of crater properties in various media over a broad range of chemical and nuclear explosive yields, studies of man-made and natural slopes, and studies directed toward the development of analytical and empirical methods of crater stability analysis. From this background, a general understanding has been developed of the effects of a cratering explosion on the surrounding medium and of physical nature of the various crater zones which are produced. The stability of nuclear crater slopes has been a subject of prime interest in the feasibility study being conducted for an Atlantic-Pacific sea-level canal. Based on experimental evidence assembled to date, nuclear crater slopes in dry dock and dry alluvium have an initially stable configuration. There have been five nuclear craters produced to date with yields of 0.4 kt or more on which observations are based and the initial configurations of these craters have remained stable for over seven years. The medium, yield, crater dimensions, and date of event for these craters are summarized. It is interesting to note that the Sedan Crater has been subjected to strong seismic motions from nearby detonations without adverse effects.

Classification of Meteorites and Micrometeorites

Science.gov (United States)

Maurette, Michel

Archeologists only started to trace back successfully the advance of the Roman legions, trade patterns and the evolution of manufacturing techniques in Roman time, once they found an efficient scheme of classification for the fragments of amphora used to transport wine for the soldiers. Similarly, the classification of meteorites and micrometeorites is an essential step in the exploitation of these extraterrestrial debris. We recall that one of the main objectives of meteoriticists over the last 30 years was to find the most primitive objects of the solar system, which have been the least reprocessed since the formation of the early solar nebula, with the view to exploit them as reliable archivist of our distant past. This section outlines some of the methods used to classify meteorites and Antarctic micrometeorites. It also summarizes some of the key features of the surprisingly simple relationship between micrometeorites and a relatively rare group of stony meteorites, the hydrous carbonaceous CM-type chondrites, which was only confirmed recently after the study of the Concordia micrometeorites collected in central Antarctica in January 2002. A more technical discussion of this relationship presented in Sect. 25 will allow its extension to the smaller micrometeorites collected by NASA in the stratosphere. The book of Wasson (1985) is still one of the best monographs about meteorites.

SNC meteorites: Clues to martian petrologic evolution

International Nuclear Information System (INIS)

McSween, H.Y. Jr.

1985-01-01

The shergottites, nakhlites, and Chassigny (SNC meteorites) are apparently cumulate mafic and ultramafic rocks that crystallized at shallow levels in the crust of their parent body. The mineralogy and chemistry of these meteorites are remarkably like equivalent terrestrial rocks, although their ratios of Fe/(Fe+Mg) and certain incompatible elements and their oxygen isotopic compositions are distinctive. All have crystallization ages of 1.3 b.y. or younger and formed from magmas produced by partial melting of previously fractionated source regions. Isotope systematics suggest that the SNC parent body had a complex and protracted thermal history spanning most of geologic time. Some meteorites have been severely shock metamorphosed, and all were ejected from their parent body at relatively recent times, possibly in several impact events. Late crystallization ages, complex petrogenesis, and possible evidence for a large gravitational field suggest that these meteorites are derived from a large planet. Trapped gases in shergottite shock melts have compositions similar to the composition measured in the Martian atmosphere. Ejection of Martian meteorites may have been accomplished by acceleration of near-surface spalls or other mechanisms not fully understood. If SNC meteorites are of Martian origin, they provide important information on planetary composition and evolution. The bulk composition and redox state of the Martian mantle, as constrained by shergottite phase equilibria, must be more earthlike than most current models. Planetary thermal models should benefit from data on the abundances of radioactive heat sources, the melting behavior of the mantle, and the timing of planetary differentiation

Crater Mound Formation by Wind Erosion on Mars

Science.gov (United States)

Steele, L. J.; Kite, E. S.; Michaels, T. I.

2018-01-01

Most of Mars' ancient sedimentary rocks by volume are in wind-eroded sedimentary mounds within impact craters and canyons, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different crater and mound morphologies to understand the formation of sedimentary mounds. As crater depth increases, slope winds produce increased erosion near the base of the crater wall, forming mounds. Peak erosion rates occur when the crater depth is ˜2 km. Mound evolution depends on the size of the host crater. In smaller craters mounds preferentially erode at the top, becoming more squat, while in larger craters mounds become steeper sided. This agrees with observations where smaller craters tend to have proportionally shorter mounds and larger craters have mounds encircled by moats. If a large-scale sedimentary layer blankets a crater, then as the layer recedes across the crater it will erode more toward the edges of the crater, resulting in a crescent-shaped moat. When a 160 km diameter mound-hosting crater is subject to a prevailing wind, the surface wind stress is stronger on the leeward side than on the windward side. This results in the center of the mound appearing to "march upwind" over time and forming a "bat-wing" shape, as is observed for Mount Sharp in Gale crater.

Geological mapping of lunar highland crater Lalande: Topographic configuration, morphology and cratering process

Science.gov (United States)

Li, Bo; Ling, Zongcheng; Zhang, Jiang; Chen, Jian; Liu, ChangQing; Bi, Xiangyu

2018-02-01

Highland crater Lalande (4.45°S, 8.63°W; D = 23.4 km) is located on the PKT area of the lunar near side, southeast of the Mare Insularum. It is a complex crater in Copernican era and has three distinguishing features: high silicic anomaly, the highest Th abundance and special landforms on its floor. There are some low-relief bulges on the left of Lalande's floor with regular circle or ellipse shapes. They are ∼250-680 m wide and ∼30-91 m high with maximum flank slopes >20°. There are two possible scenarios for the formation of these low-relief bulges which are impact melt products or young silicic volcanic eruptions. We estimated the absolute model ages of the ejecta deposits, several melt ponds and the hummocky floor and determined the ratio of diameter and depth of the crater Lalande. In addition, we found some similar bugle features within other Copernican-aged craters and there were no volcanic source vents on Lalande's floor. Thus, we hypothesized that these low-relief bulges were most consistent with an origin of impact melts during the crater formation instead of small and young volcanic activities occurring on the floor. Based on Kaguya Terrain Camera (TC) ortho-mosaic and Digital Terrain Model (DTM) data produced by TC imagery in stereo, geological units and some linear features on the floor and wall of Lalande have been mapped. Eight geological units are organized by crater floor units: hummocky floor, central peak and low-relief bulges; and crater wall units: terraced walls, channeled and veneered walls, interior walls, mass wasting areas, blocky areas, and melt ponds. These geological units and linear features provided us a chance to understand some details of the cratering process and elevation differences on the floor. We proposed that subsidence due to melt cooling, late-stage wall collapse and rocks uplifted from beneath the surface could be the possible causes of the observed elevation differences on Lalande's floor.

What Really Happened to Earth's Older Craters?

Science.gov (United States)

Bottke, William; Mazrouei, Sara; Ghent, Rebecca; Parker, Alex

2017-10-01

Most assume the Earth’s crater record is heavily biased, with erosion/tectonics destroying older craters. This matches expectations, but is it actually true? To test this idea, we compared Earth’s crater record, where nearly all D ≥ 20 km craters are pick out from older craters with eroded fragments. Moreover, an inverse relationship between rock abundance (RA) and crater age exists. Using measured RA values, we computed ages for 111 rocky craters with D ≥ 10 km that formed between 80°N and 80°S over the last 1 Gyr.We found several surprising results. First, the production rate of D ≥ 10 km lunar craters increased by a factor of 2.2 [-0.9, +4.4; 95% confidence limits] over the past 250 Myr compared to the previous 750 Myr. Thus, the NEO population is higher now than it has been for the last billion years. Second, the size and age distributions of lunar and terrestrial craters for D ≥ 20 km over the last 650 Myr have similar shapes. This implies that crater erasure must be limited on stable terrestrial terrains; in an average sense, for a given region, the Earth either keeps all or loses all of its D ≥ 20 craters at the same rate, independent of size. It also implies the observed deficit of large terrestrial craters between 250-650 Myr is not preservation bias but rather reflects a distinctly lower impact flux. We predict 355 ± 86 D ≥ 20 km craters formed on Earth over the last 650 Myr. Only 38 ± 6 are known, so the ratio, 10.7 ± 3.1%, is a measure of the Earth’s surface that is reasonably stable to large crater formation over 650 Myr. If erosion had dominated, the age distribution of terrestrial craters would be strongly skewed toward younger ages, which is not observed. We predict Chicxulub-type impacts were rare over the last Gyr, with the event 66 Ma a probable byproduct of the current high terrestrial impact flux.

How old is Autolycus crater?

Science.gov (United States)

Hiesinger, Harald; Pasckert, Jan Henrik; van der Bogert, Carolyn H.; Robinson, Mark S.

2016-04-01

Accurately determining the lunar cratering chronology is prerequisite for deriving absolute model ages (AMAs) across the lunar surface and throughout the Solar System [e.g., 1]. However, the lunar chronology is only constrained by a few data points over the last 1 Ga and there are no calibration data available between 1 and 3 Ga and beyond 3.9 Ga [2]. Rays from Autolycus and Aristillus cross the Apollo 15 landing site and presumably transported material to this location [3]. [4] proposed that at the Apollo 15 landing site about 32% of any exotic material would come from Autolycus crater and 25% would come from Aristillus crater. [5,6] proposed that the 39Ar-40Ar age of 2.1 Ga derived from three petrologically distinct, shocked Apollo 15 KREEP basalt samples, date Autolycus crater. Grier et al. [7] reported that the optical maturity (OMAT) characteristics of these craters are indistinguishable from the background values despite the fact that both craters exhibit rays that were used to infer relatively young, i.e., Copernican ages [8,9]. Thus, both OMAT characteristics and radiometric ages of 2.1 Ga and 1.29 Ga for Autolycus and Aristillus, respectively, suggest that these two craters are not Copernican in age. [10] interpreted newer U-Pb ages of 1.4 and 1.9 Ga from sample 15405 as the formation ages of Aristillus and Autolycus. If Autolycus is indeed the source of the dated exotic material collected at the Apollo 15 landing site, than performing crater size frequency distribution (CSFD) measurements for Autolycus offers the possibility to add a new calibration point to the lunar chronology, particularly in an age range that was previously unconstrained. We used calibrated and map-projected LRO NAC images to perform CSFD measurements within ArcGIS, using CraterTools [11]. CSFDs were then plotted with CraterStats [12], using the production and chronology functions of [13]. We determined ages of 3.72 and 3.85 Ga for the interior (Ai1) and ejecta area Ae3, which we

Experimental simulation of impact cratering on icy satellites

Science.gov (United States)

Greeley, R.; Fink, J. H.; Gault, D. E.; Guest, J. E.

1982-01-01

Cratering processes on icy satellites were simulated in a series of 102 laboratory impact experiments involving a wide range of target materials. For impacts into homogeneous clay slurries with impact energies ranging from five million to ten billion ergs, target yield strengths ranged from 100 to 38 Pa, and apparent viscosities ranged from 8 to 200 Pa s. Bowl-shaped craters, flat-floored craters, central peak craters with high or little relief, and craters with no relief were observed. Crater diameters increased steadily as energies were raised. A similar sequence was seen for experiment in which impact energy was held constant but target viscosity and strength progressively decreases. The experiments suggest that the physical properties of the target media relative to the gravitationally induced stresses determined the final crater morphology. Crater palimpsests could form by prompt collapse of large central peak craters formed in low target strength materials. Ages estimated from crater size-frequency distributions that include these large craters may give values that are too high.

Mössbauer study of Slovak meteorites

Science.gov (United States)

Lipka, J.; Sitek, J.; Dekan, J.; Degmová, J.; Porubčan, V.

2013-04-01

57Fe Mössbauer spectroscopy was used as an analytical tool in the investigation of iron containing compounds of two meteorites (Rumanová and Košice) out of total of six which had fallen on Slovak territory. In the magnetic fraction of the iron bearing compounds in the Rumanová meteorite, maghemite, troilite and Fe-Ni alloy were identified. In the non-magnetic fraction silicate phases were found, such as olivine and pyroxene. The paramagnetic component containing Fe3 + ions corresponds probably to small superparamagnetic particles. The Košice meteorite was found near the town of Košice in February 2010. Its magnetic fraction consists of a Fe-Ni alloy with the Mössbauer parameters of the magnetic field corresponding to kamacite α-Fe(Ni, Co) and troilite. The non-magnetic part consists of Fe2 + phases such as olivine and pyroxene and traces of a Fe3 + phase. The main difference between these meteorites is their iron oxide content. These kinds of analyses can bring important knowledge about phases and compounds formed in extraterrestrial conditions, which have other features than their terrestrial analogues.

Analyses of Rumanová meteorite

Science.gov (United States)

Lipka, J.; Sitek, J.; Dekan, J.; Sedlačková, K.

2014-04-01

Mössbauer spectroscopy was used as an analytical tool in investigation of iron containing compounds of Rumanová meteorite found on Slovak territory and it was classified as chondrite H. The results showed that the Mössbauer spectra consist of magnetic and non-magnetic components related to different iron-bearing phases. In non-magnetic part, olivine, pyroxene, and traces of Fe3 + phases have been identified. The magnetically ordered part of the Rumanová meteorite spectrum consists of kamacite, troilite and the third additional component corresponds to hydroxides originating from weathering due to being long time on the Earth surface. The weathering products can be recognised mainly as maghemite, however traces of other weathering components as akagaenite, goethite and magnetite cannot be excluded. On the contrary to Rumanová, no weathering products have been found in the sample of Košice meteorite which fell on the territory of Slovakia in February 2010 and has been investigated a few months after the fall.

Organic Chemistry of Carbonaceous Meteorites

Science.gov (United States)

Cronin, John R.

2001-01-01

Chiral and carbon-isotopic analyses of isovaline have been carried out on numerous samples of the Murchison and one sample of the Murray carbonaceous chondrite. The isovaline was found to be heterogeneous with regard to enantiomeric excess (ee) both between samples and within a single Murchison sample. L-Excesses ranging from 0 to 15% were observed. The isovaline delta(sup 13) C was found to be about +18%. No evidence was obtained suggesting terrestrial contamination in the more abundant L-enantiomer. A correlation was observed between isovaline (also alpha - aminoisobutyric acid) concentration and PCP content of five CM chondrites. It is suggested that isovaline, along with other meteoritic a-methyl amino acids with ee, are of presolar origin. The possible formation of ee in extraterrestrial amino acids by exposure to circularly polarized light or by magnetochiral photochemistry is discussed. Key words: Murchison meteorite, Murray meteorite, amino acids, isovaline, chirality, carbon isotopes, PCP.

Meteorite impact in the ocean

Science.gov (United States)

Strelitz, R.

1979-01-01

In the present study, the dynamic of hypervelocity impacts and crater formation in water are examined with allowance for the unique properties of water. More precisely, the transient crater calculated is permitted to relax and act as a source of oceanic surface waves.

Craters of elevation / forced folds: more examples of shallow magma accumulation and its consequences

Science.gov (United States)

van Wyk de Vries, Benjamin; Marquez, Alvaro; Craig, Magee; Valdislav, Rapprich; Hetherington, Rachel; Bastow, Ian

2016-04-01

Craters of elevation are uplifts with apical depressions that are caused by shallow magma intrusion. Forced folds are dome-like folds caused by magma intrusion that also have apical extensional structures. They are the same feature described from the different viewpoints of the volcanologist and the structural geologist. While working on such features in the Chaîne des Puys (Central France), and Ethiopia we have been searching for other examples in the world. This is our most up to date review of such phenomena taken from a global search in the world of volcanology where some stunning examples are seen in the landscape, and in outcrop. We also show such features from tectonics data and literature, where such features are superbly displayed in seismic data. We take three examples, the Puy de Gouttes, in the Chaîne des Puys, the Montana Encantada in Lanzarote, which we have mapped in the field, and the Diamond Craters National Monument in Oregon to show the different structures and possible evolutionary trends that such features can follow. We use the observations to integrate the possible eruptive, deformational and structural events that can combine in a forced fold to create the surface features observed at such craters of elevation. The hazard implications of the growth and destruction of such features are assessed.

Lunar Bouguer gravity anomalies - Imbrian age craters

Science.gov (United States)

Dvorak, J.; Phillips, R. J.

1978-01-01

The Bouguer gravity of mass anomalies associated with four Imbrian age craters, analyzed in the present paper, are found to differ considerably from the values of the mass anomalies associated with some young lunar craters. Of the Imbrian age craters, only Piccolomini exhibits a negative gravity anomaly (i.e., a low density region) which is characteristic of the young craters studied. The Bouguer gravity anomalies are zero for each of the remaining Imbrian age craters. Since, Piccolomini is younger, or at least less modified, than the other Imbrian age craters, it is suggested that the processes responsible for the post-impact modification of the Imbrian age craters may also be responsible for removing the negative mass anomalies initially associated with these features.

Fused Bead Analysis of Diogenite Meteorites

Science.gov (United States)

Mittlefehldt, D.W.; Beck, B.W.; McSween, H.Y.; Lee, C.T. A.

2009-01-01

Bulk rock chemistry is an essential dataset in meteoritics and planetary science [1]. A common method used to obtain the bulk chemistry of meteorites is ICP-MS. While the accuracy, precision and low detection limits of this process are advantageous [2], the sample size used for analysis (approx.70 mg) can be a problem in a field where small and finite samples are the norm. Fused bead analysis is another bulk rock analytical technique that has been used in meteoritics [3]. This technique involves forming a glass bead from 10 mg of sample and measuring its chemistry using a defocused beam on a microprobe. Though the ICP-MS has lower detection limits than the microprobe, the fused bead method destroys a much smaller sample of the meteorite. Fused bead analysis was initially designed for samples with near-eutectic compositions and low viscosities. Melts generated of this type homogenize at relatively low temperatures and produce primary melts near the sample s bulk composition [3]. The application of fused bead analysis to samples with noneutectic melt compositions has not been validated. The purpose of this study is to test if fused bead analysis can accurately determine the bulk rock chemistry of non-eutectic melt composition meteorites. To determine this, we conduct two examinations of the fused bead. First, we compare ICP-MS and fused bead results of the same samples using statistical analysis. Secondly, we inspect the beads for the presence of crystals and chemical heterogeneity. The presence of either of these would indicate incomplete melting and quenching of the bead.

SMALL CRATERS AND THEIR DIAGNOSTIC POTENTIAL

Directory of Open Access Journals (Sweden)

R. Bugiolacchi

2017-07-01

Full Text Available I analysed and compared the size-frequency distributions of craters in the Apollo 17 landing region, comprising of six mare terrains with varying morphologies and cratering characteristics, along with three other regions allegedly affected by the same secondary event (Tycho secondary surge. I propose that for the smaller crater sizes (in this work 9–30 m, a] an exponential curve of power −0.18D can approximate Nkm−2 crater densities in a regime of equilibrium, while b] a power function D−3 closely describes the factorised representation of craters by size (1 m. The saturation level within the Central Area suggests that c] either the modelled rates of crater erosion on the Moon should be revised, or that the Tycho event occurred much earlier in time than the current estimate. We propose that d] the size-frequency distribution of small secondary craters may bear the signature (in terms of size-frequency distribution of debris/surge of the source impact and that this observation should be tested further.

LU60645GT and MA132843GT Catalogues of Lunar and Martian Impact Craters Developed Using a Crater Shape-based Interpolation Crater Detection Algorithm for Topography Data

Science.gov (United States)

Salamuniccar, Goran; Loncaric, Sven; Mazarico, Erwan Matias

2012-01-01

For Mars, 57,633 craters from the manually assembled catalogues and 72,668 additional craters identified using several crater detection algorithms (CDAs) have been merged into the MA130301GT catalogue. By contrast, for the Moon the most complete previous catalogue contains only 14,923 craters. Two recent missions provided higher-quality digital elevation maps (DEMs): SELENE (in 1/16° resolution) and Lunar Reconnaissance Orbiter (we used up to 1/512°). This was the main motivation for work on the new Crater Shape-based interpolation module, which improves previous CDA as follows: (1) it decreases the number of false-detections for the required number of true detections; (2) it improves detection capabilities for very small craters; and (3) it provides more accurate automated measurements of craters' properties. The results are: (1) LU60645GT, which is currently the most complete (up to D>=8 km) catalogue of Lunar craters; and (2) MA132843GT catalogue of Martian craters complete up to D>=2 km, which is the extension of the previous MA130301GT catalogue. As previously achieved for Mars, LU60645GT provides all properties that were provided by the previous Lunar catalogues, plus: (1) correlation between morphological descriptors from used catalogues; (2) correlation between manually assigned attributes and automated measurements; (3) average errors and their standard deviations for manually and automatically assigned attributes such as position coordinates, diameter, depth/diameter ratio, etc; and (4) a review of positional accuracy of used datasets. Additionally, surface dating could potentially be improved with the exhaustiveness of this new catalogue. The accompanying results are: (1) the possibility of comparing a large number of Lunar and Martian craters, of e.g. depth/diameter ratio and 2D profiles; (2) utilisation of a method for re-projection of datasets and catalogues, which is very useful for craters that are very close to poles; and (3) the extension of the

Terrestrial and exposure histories of Antarctic meteorites

International Nuclear Information System (INIS)

Nishiizumi, K.

1986-01-01

Records of cosmogenic effects were studied in a large suite of Antarctic meteorites. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic meteorites provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the meteorite on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40

Terrestrial and exposure histories of Antarctic meteorites

Science.gov (United States)

Nishiizumi, K.

1986-01-01

Records of cosmogenic effects were studied in a large suite of Antarctic meteorites. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic meteorites provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the meteorite on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40.

NASA Lunar and Meteorite Sample Disk Program

Science.gov (United States)

Foxworth, Suzanne

2017-01-01

The Lunar and Meteorite Sample Disk Program is designed for K-12 classroom educators who work in K-12 schools, museums, libraries, or planetariums. Educators have to be certified to borrow the Lunar and Meteorite Sample Disks by attending a NASA Certification Workshop provided by a NASA Authorized Sample Disk Certifier.

Blocky craters: implications about the lunar megaregolith

International Nuclear Information System (INIS)

Thompson, T.W.; Roberts, W.J.; Hartmann, W.K.; Shorthill, R.W.; Zisk, S.H.

1979-01-01

Radar, infrared, and photogeologic properties of lunar craters have been studied to determine whether there is a systematic difference in blocky craters between the maria and terrae and whether this difference may be due to a deep megaregolith of pulverized material forming the terra surface, as opposed to a layer of semi-coherent basalt flows forming the mare surface. Some 1310 craters from about 4 to 100 km diameter have been catalogued as radar and/or infrared anomalies. In addition, a study of Apollo Orbital Photography confirmed that the radar and infrared anomalies are correlated with blocky rubble around the crater. Analysis of the radar and infrared data indicated systematic terra-mare differences. Fresh terra craters smaller than 12 km were less likely to be infrared and radar anomalies than comparable mare craters: but terra and mare craters larger than 12 km had similar infrared and radar signatures. Also, there are many terra craters which are radar bright but not infrared anomalies. The authors interpretation of these data is that while the maria are rock layers (basaltic flow units) where craters eject boulder fields, the terrae are covered by relatively pulverized megaregolith at least 2 km deep, where craters eject less rocky rubble. Blocky rubble, either in the form of actual rocks or partly consolidated blocks, contributes to the radar and infrared signatures of the crater. However, aging by impacts rapidly destroys these effects, possibly through burial by secondary debris or by disintegration of the blocks themselves, especially in terra regions. (Auth.)

Machine cataloging of impact craters on Mars

Science.gov (United States)

Stepinski, Tomasz F.; Mendenhall, Michael P.; Bue, Brian D.

2009-09-01

This study presents an automated system for cataloging impact craters using the MOLA 128 pixels/degree digital elevation model of Mars. Craters are detected by a two-step algorithm that first identifies round and symmetric topographic depressions as crater candidates and then selects craters using a machine-learning technique. The system is robust with respect to surface types; craters are identified with similar accuracy from all different types of martian surfaces without adjusting input parameters. By using a large training set in its final selection step, the system produces virtually no false detections. Finally, the system provides a seamless integration of crater detection with its characterization. Of particular interest is the ability of our algorithm to calculate crater depths. The system is described and its application is demonstrated on eight large sites representing all major types of martian surfaces. An evaluation of its performance and prospects for its utilization for global surveys are given by means of detailed comparison of obtained results to the manually-derived Catalog of Large Martian Impact Craters. We use the results from the test sites to construct local depth-diameter relationships based on a large number of craters. In general, obtained relationships are in agreement with what was inferred on the basis of manual measurements. However, we have found that, in Terra Cimmeria, the depth/diameter ratio has an abrupt decrease at ˜38°S regardless of crater size. If shallowing of craters is attributed to presence of sub-surface ice, a sudden change in its spatial distribution is suggested by our findings.

Oral histories in meteoritics and planetary science—XXV: Vagn F. Buchwald

Science.gov (United States)

Sears, Derek W. G.

2014-07-01

Vagn Buchwald (Fig. 1) was born in Copenhagen where he attended school and college. Then after 18 months of military service, he assumed a position at the Technical University of Copenhagen. A few years later, he was presented with a piece of the Cape York meteorite, which led to an interest in iron meteorites. Through a campaign of informed searching, Vagn found the 20 ton Agpalilik meteorite (part of the Cape York shower) on 31st July 1963 and by September 1967 had arranged its transport to Copenhagen. After sorting and describing the Danish collection, which included application of the Fe-Ni-P phase diagram to iron meteorite mineralogy, Vagn was invited to sort and describe other iron meteorite collections. This led to a 7 yr project to write his monumental Handbook of Iron Meteorites. Vagn spent 3 yr in the United States and visited most of the world's museums, the visit to Berlin being especially important since the war had left their iron meteorites in bad condition and without labels. During a further decade or more of iron meteorite research, he documented natural and anthropomorphic alterations experienced by iron meteorites, discovered five new minerals (roaldite, carlsbergite, akaganeite, hibbingite, and arupite); had a mineral (buchwaldite, NaCaPO4) and asteroid (3209 Buchwald 1982 BL1) named after him; and led expeditions to Chile, Namibia, and South Africa in search of iron meteorites and information on them. Vagn then turned his attention to archeological metal artifacts. This work resulted in many papers and culminated in two major books on the subject published in 2005 and 2008, after his retirement in 1998. Vagn Buchwald has received numerous Scandinavian awards and honors, and served as president of the Meteoritical Society in 1981-1982.

Nuclear cratering on a digital computer

International Nuclear Information System (INIS)

Terhune, R.W.; Stubbs, T.F.; Cherry, J.T.

1970-01-01

Computer programs based on the artificial viscosity method are applied to developing an understanding of the physics of cratering, with emphasis on cratering by nuclear explosives. Two established codes, SOC (spherical symmetry) and TENSOR (cylindrical symmetry), are used to illustrate the effects of variations in the material properties of various media on the cratering processes, namely shock, spall, and gas acceleration. Water content is found to be the most important material property, followed by strength, porosity, and compressibility. Crater profile calculations are presented for Pre-Gondola Charley (20-ton nitromethane detonation in shale) and Sedan (100-kt nuclear detonation in alluvium). Calculations also are presented for three 1-Mt yields in saturated Divide basalt and 1-Mt yield in dry Buckboard basalt, to show crater geometry as a function of the burial depth for large explosive yields. The calculations show, for megaton-level yields, that gas acceleration is the dominate mechanism in determining crater size and depends in turn on the water content in the medium. (author)

Nuclear cratering on a digital computer

Energy Technology Data Exchange (ETDEWEB)

Terhune, R W; Stubbs, T F; Cherry, J T [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1970-05-01

Computer programs based on the artificial viscosity method are applied to developing an understanding of the physics of cratering, with emphasis on cratering by nuclear explosives. Two established codes, SOC (spherical symmetry) and TENSOR (cylindrical symmetry), are used to illustrate the effects of variations in the material properties of various media on the cratering processes, namely shock, spall, and gas acceleration. Water content is found to be the most important material property, followed by strength, porosity, and compressibility. Crater profile calculations are presented for Pre-Gondola Charley (20-ton nitromethane detonation in shale) and Sedan (100-kt nuclear detonation in alluvium). Calculations also are presented for three 1-Mt yields in saturated Divide basalt and 1-Mt yield in dry Buckboard basalt, to show crater geometry as a function of the burial depth for large explosive yields. The calculations show, for megaton-level yields, that gas acceleration is the dominate mechanism in determining crater size and depends in turn on the water content in the medium. (author)

What we know about Oslo meteorite from cosmogenic isotope analysis

Science.gov (United States)

Tymiński, Z.; Stolarz, M.; Kubalczak, T.; Zaręba, P.; Burski, M.; Bilet, M.; Miśta, E.; Tymińska, K.; Kołakowska, E.; Burakowska, A.; Żołądek, P.; Olech, A.; Wiśniewski, M.; Listkowska, A.; Saganowski, P.

2015-10-01

The fragments of an asteroid that had crashed over Norway were found in a few locations in Oslo at the beginning of March 2012. Later on some pieces of meteorite from the most South area were collected by the Meteoritical Section members of Comet and Meteor Workshop (PKiM) with the help of local meteoritical authorities. One meteorite fragment of 32g was used to measure cosmogenic radionuclides using non-destructive high-resolution gamma spectrometry technique. Five radioisotopes such as Al-26, Na-22, Mn-54, Co-57 and Co-60 were detected

THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

Energy Technology Data Exchange (ETDEWEB)

Pizzarello, Sandra, E-mail: pizzar@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85018-1604 (United States)

2014-12-01

HCN is ubiquitous in extraterrestrial environments and is central to current theories on the origin of early solar system organic compounds such as amino acids. These compounds, observed in carbonaceous meteorites, were likely important in the origin and/or evolution of early life. As part of our attempts to understand the origin(s) of meteoritic CN{sup –}, we have analyzed the {sup 15}N/{sup 14}N isotopic composition of HCN gas released from water extracts of the Murchison meteorite and found its value to be near those of the terrestrial atmosphere. The findings, when evaluated viz-a-viz molecular abundances and isotopic data of meteoritic organic compounds, suggest that HCN formation could have occurred during the protracted water alteration processes known to have affected the mineralogy of many asteroidal bodies during their solar residence. This was an active synthetic stage, which likely involved simple gasses, organic molecules, their presolar precursors, as well as mineral catalysts and would have lead to the formation of molecules of differing isotopic composition, including some with solar values.

AMSNEXRAD-Automated detection of meteorite strewnfields in doppler weather radar

Science.gov (United States)

Hankey, Michael; Fries, Marc; Matson, Rob; Fries, Jeff

2017-09-01

For several years meteorite recovery in the United States has been greatly enhanced by using Doppler weather radar images to determine possible fall zones for meteorites produced by witnessed fireballs. While most fireball events leave no record on the Doppler radar, some large fireballs do. Based on the successful recovery of 10 meteorite falls 'under the radar', and the discovery of radar on more than 10 historic falls, it is believed that meteoritic dust and or actual meteorites falling to the ground have been recorded on Doppler weather radar (Fries et al., 2014). Up until this point, the process of detecting the radar signatures associated with meteorite falls has been a manual one and dependent on prior accurate knowledge of the fall time and estimated ground track. This manual detection process is labor intensive and can take several hours per event. Recent technological developments by NOAA now help enable the automation of these tasks. This in combination with advancements by the American Meteor Society (Hankey et al., 2014) in the tracking and plotting of witnessed fireballs has opened the possibility for automatic detection of meteorites in NEXRAD Radar Archives. Here in the processes for fireball triangulation, search area determination, radar interfacing, data extraction, storage, search, detection and plotting are explained.

Micro-mapping Meteorite Surfaces on Mars using Microscopic Imager Mosaics — A Tool for Unraveling Weathering History at Meridiani Planum

Science.gov (United States)

Ashley, J. W.; Herkenhoff, K. E.; Golombek, M. P.; Johnson, J. R.

2012-12-01

evidence that coating deposition (interpreted as a result of water interaction) was geologically recent: Because the margins of many oxide coating deposits are concentric to and slightly removed from regmaglypt rim crests, the latest cycle is interpreted as a time of coating removal, not deposition, with these topographic high points representing zones of greatest erosional attack. Assuming the oxide coating has a low to moderate hardness, this observation implies relative geologic youth for the coating. However, it is unknown whether oxide deposits are stable or actively eroded by free basaltic sand grains [e.g., 6] in the modern epoch. The high science return from ongoing meteorite studies at MER landing sites supports their consideration if meteorites are also encountered by the Mars Science Laboratory Curiosity rover in Gale Crater.

Isotopic variations in primitive meteorites

International Nuclear Information System (INIS)

Clayton, R.N.; Chicago Univ., IL; Chicago Univ., IL

1981-01-01

The presence of large internal 16 O variability in ordinary chondrites greatly extends the range of meteorite types in which this phenomenon has been observed. These results may lead to identification of major gas and dust reservoirs in the cloud from which the Solar System formed. The demonstration that live 107 Pd was present in the differentiated parent bodies of some iron meteorites supports the million year time scale between a major nucleosynthetic event and Solar System formation, as implied by the presence of live 26 Al in carbonaceous chondrites. However, the variability of radiogenic 26 Mg abundances in these meteorites makes it clear that the data cannot be interpreted simply in terms of time variations. Models of nucleosynthesis for elements from calcium to the iron peak should be aided by the new observations of abundances of titanium isotopes. Progress has been made in establishing the carrier phases of isotopically anomalous xenon and krypton. The apparent location of anomalous xenon and 14 N-rich nitrogen in identical carriers supports the notion that nucleosynthetic anomalies in nitrogen are also present in Allende. (author)

Rare stable isotopes in meteorites

International Nuclear Information System (INIS)

Wilson, G.C.

1981-01-01

Secondary Ion Mass Spectrometry (SIMS) using accelerators has been applied with success to cosmic ray exposure ages and terrestrial residence times of meteorites by measuring cosmogenic nuclides of Be, Cl, and I. It is proposed to complement this work with experiments on rare stable isotopes, in the hope of setting constraints on the processes of solar nebula/meteoritic formation. The relevant species can be classified as: a) daughter products of extinct nuclides (halflife less than or equal to 2 x 10 8 y) -chronology of the early solar system; b) products of high temperature astrophysical processes - different components incorporated into the solar nebula; and c) products of relatively low temperature processes, stellar winds and cosmic ray reactions - early solar system radiation history. The use of micron-scale primary ion beams will allow detailed sampling of phases within meteorites. Strategies of charge-state selection, molecular disintegration and detection should bring a new set of targets within analytical range. The developing accelerator field is compared to existing (keV energy) ion microprobes

Solar flare irradiation records in Antarctic meteorites

International Nuclear Information System (INIS)

Goswami, J.N.

1981-01-01

Observations of solar flare heavy nuclei tracks in eight Antartic meteorite samples are reported. Two of these were interior specimens from an L-3 chondrite which contained track-rich grains (olivine) indicating their exposure to solar flare irradiation before compaction of the meteorite. Preliminary noble gas data also indicate the presence of solar-type gases. (U.K.)

Worldwide Weather Radar Imagery May Allow Substantial Increase in Meteorite Fall Recovery

Science.gov (United States)

Fries, Marc; Matson, Robert; Schaefer, Jacob; Fries, Jeffery; Hankey, Mike; Anderson, Lindsay

2014-01-01

Weather radar imagery is a valuable new technique for the rapid recovery of meteorite falls, to include falls which would not otherwise be recovered (e.g. Battle Mountain). Weather radar imagery reveals about one new meteorite fall per year (18 falls since 1998), using weather radars in the United States alone. However, an additional 75 other nations operate weather radar networks according to the UN World Meteorological Organization (WMO). If the imagery of those radars were analyzed, the current rate of meteorite falls could be improved considerably, to as much as 3.6 times the current recovery rate based on comparison of total radar areal coverage. Recently, the addition of weather radar imagery, seismometry and internet-based aggregation of eyewitness reports has improved the speed and accuracy of fresh meteorite fall recovery [e.g. 1,2]. This was demonstrated recently with the radar-enabled recovery of the Sutter's Mill fall [3]. Arguably, the meteorites recovered via these methods are of special scientific value as they are relatively unweathered, fresh falls. To illustrate this, a recent SAO/NASA ADS search using the keyword "meteorite" shows that all 50 of the top search results included at least one named meteorite recovered from a meteorite fall. This is true even though only 1260 named meteorite falls are recorded among the >49,000 individual falls recorded in the Meteoritical Society online database. The US NEXRAD system used thus far to locate meteorite falls covers most of the United States' surface area. Using a WMO map of the world's weather radars, we estimate that the total coverage of the other 75 national weather radar networks equals about 3.6x NEXRAD's coverage area. There are two findings to draw from this calculation: 1) For the past 16 years during which 18 falls are seen in US radar data, there should be an additional 65 meteorite falls recorded in worldwide radar imagery. Also: 2) if all of the world's radar data could be analyzed, the

Polygons on Crater Floor

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-357, 11 May 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a pattern of polygons on the floor of a northern plains impact crater. These landforms are common on crater floors at high latitudes on Mars. Similar polygons occur in the arctic and antarctic regions of Earth, where they indicate the presence and freeze-thaw cycling of ground ice. Whether the polygons on Mars also indicate water ice in the ground is uncertain. The image is located in a crater at 64.8oN, 292.7oW. Sunlight illuminates the scene from the lower left.

A Method for Estimating Meteorite Fall Mass from Weather Radar Data

Science.gov (United States)

Laird, C.; Fries, M.; Matson, R.

2017-01-01

Techniques such as weather RADAR, seismometers, and all-sky cameras allow new insights concerning the physics of meteorite fall dynamics and fragmentation during "dark flight", the period of time between the end of the meteor's luminous flight and the concluding impact on the Earth's surface. Understanding dark flight dynamics enables us to rapidly analyze the characteristics of new meteorite falls. This analysis will provide essential information to meteorite hunters to optimize recovery, increasing the frequency and total mass of scientifically important freshly-fallen meteorites available to the scientific community. We have developed a mathematical method to estimate meteorite fall mass using reflectivity data as recorded by National Oceanic and Atmospheric Administration (NOAA) Next Generation RADAR (NEXRAD) stations. This study analyzed eleven official and one unofficial meteorite falls in the United States and Canada to achieve this purpose.

Physical properties of Martian meteorites: Porosity and density measurements

Science.gov (United States)

Coulson, Ian M.; Beech, Martin; Nie, Wenshuang

Martian meteorites are fragments of the Martian crust. These samples represent igneous rocks, much like basalt. As such, many laboratory techniques designed for the study of Earth materials have been applied to these meteorites. Despite numerous studies of Martian meteorites, little data exists on their basic structural characteristics, such as porosity or density, information that is important in interpreting their origin, shock modification, and cosmic ray exposure history. Analysis of these meteorites provides both insight into the various lithologies present as well as the impact history of the planet's surface. We present new data relating to the physical characteristics of twelve Martian meteorites. Porosity was determined via a combination of scanning electron microscope (SEM) imagery/image analysis and helium pycnometry, coupled with a modified Archimedean method for bulk density measurements. Our results show a range in porosity and density values and that porosity tends to increase toward the edge of the sample. Preliminary interpretation of the data demonstrates good agreement between porosity measured at 100× and 300× magnification for the shergottite group, while others exhibit more variability. In comparison with the limited existing data for Martian meteorites we find fairly good agreement, although our porosity values typically lie at the low end of published values. Surprisingly, despite the increased data set, there is little by way of correlation between either porosity or density with parameters such as shock effect or terrestrial residency. Further data collection on additional meteorite samples is required before more definitive statements can be made concerning the validity of these observations.

Floor-Fractured Craters through Machine Learning Methods

Science.gov (United States)

Thorey, C.

2015-12-01

Floor-fractured craters are impact craters that have undergone post impact deformations. They are characterized by shallow floors with a plate-like or convex appearance, wide floor moats, and radial, concentric, and polygonal floor-fractures. While the origin of these deformations has long been debated, it is now generally accepted that they are the result of the emplacement of shallow magmatic intrusions below their floor. These craters thus constitute an efficient tool to probe the importance of intrusive magmatism from the lunar surface. The most recent catalog of lunar-floor fractured craters references about 200 of them, mainly located around the lunar maria Herein, we will discuss the possibility of using machine learning algorithms to try to detect new floor-fractured craters on the Moon among the 60000 craters referenced in the most recent catalogs. In particular, we will use the gravity field provided by the Gravity Recovery and Interior Laboratory (GRAIL) mission, and the topographic dataset obtained from the Lunar Orbiter Laser Altimeter (LOLA) instrument to design a set of representative features for each crater. We will then discuss the possibility to design a binary supervised classifier, based on these features, to discriminate between the presence or absence of crater-centered intrusion below a specific crater. First predictions from different classifier in terms of their accuracy and uncertainty will be presented.

Geology of Lofn Crater, Callisto

Science.gov (United States)

Greeley, Ronald; Heiner, Sarah; Klemaszewski, James E.

2001-01-01

Lofn crater is a 180-km-diameter impact structure in the southern cratered plains of Callisto and is among the youngest features seen on the surface. The Lofn area was imaged by the Galileo spacecraft at regional-scale resolutions (875 m/pixel), which enable the general geology to be investigated. The morphology of Lofn crater suggests that (1) it is a class of impact structure intermediate between complex craters and palimpsests or (2) it formed by the impact of a projectile which fragmented before reaching the surface, resulting in a shallow crater (even for Callisto). The asymmetric pattern of the rim and ejecta deposits suggests that the impactor entered at a low angle from the northwest. The albedo and other characteristics of the ejecta deposits from Lofn also provide insight into the properties of the icy lithosphere and subsurface configuration at the time of impact. The "target" for the Lofn impact is inferred to have included layered materials associated with the Adlinda multiring structure northwest of Loh and ejecta deposits from the Heimdall crater area to the southeast. The Lofn impact might have penetrated through these materials into a viscous substrate of ductile ice or possibly liquid water. This interpretation is consistent with models of the current interior of Callisto based on geophysical information obtained from the Galileo spacecraft.

Characteristics of ejecta and alluvial deposits at Meteor Crater, Arizona and Odessa Craters, Texas: Results from ground penetrating radar

Science.gov (United States)

Grant, J. A.; Schultz, P. H.

1991-01-01

Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor Crater revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-2 m) around Meteor Crater and the main crater at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (2) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post crater drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor Crater and allow initial assessment of the gradational state if the Odessa craters.

Search for fullerenes in stone meteorites

Science.gov (United States)

Oester, M. Y.; Kuechl, D.; Sipiera, P. P.; Welch, C. J.

1994-07-01

The possibility of identifying fullerenes in stony meteorites became apparent from a paper given by Radicati de Brozolo. In this paper it was reported that fullerenes were present in the debris resulting from a collision between a micrometeoroid and an orbiting satellite. This fact generated sufficient curiosity to initiate a search for the presence of fullerenes in various stone meteorites. In the present study seven ordinary chondrites (al-Ghanim L6 (find), Dimmitt H4 (find), Lazbuddie LL5 (find), New Concord H5 (fall), Silverton H4 (find), Springlake L6 (find), and Umbarger L3/6 (find)). Four carbonaceous chondrites (ALH 83100 C2 (find), ALH 83108 C30 (find), Allende CV3 (fall), and Murchison CM2 (fall), and one achondrite (Monticello How (find)) were analyzed for the presence of fullerenes. The analytical procedure employed was as follows: 100 mg of meteorite was ground up with a mortar and pestle; 10 mL of toluene was then added and the mixture was refluxed for 90 min; this mixture was then filtered through a short column of silica; a 50 microliter sample was then analyzed by high pressure liquid chromatography (HPLC) using a Buckyclutcher I column with a mobile phase consisting of equal volumes of toluene and hexane at a flow rate of 1.00 mg per minute, with detection at 330 and 600 nm. Three of the meteorites, Allende, Murchison, and al-Ghanim, gave HPLC traces containing peaks with similar retention times to the HPLC trace of an authentic fullerene C60. However, further analysis using an HPLC instrument equipped with a diode-array detector failed to confirm any of the substances detected in the three meteorites as C60. Additional analyses will be conducted to identify what the HPLC traces actually represent.

Pigeonholing planetary meteorites: The lessons of misclassification of EET87521 and ALH84001

Science.gov (United States)

Lindstrom, M. M.; Treiman, A. H.; Mittlefehldt, D. W.

1994-01-01

The last few years have provided two noteworthy examples of misclassifications of achondritic meteorites because the samples were new kinds of meteorites from planetary rather than asteroidal parent bodies. Basaltic lunar meteorite EET87521 was misclassified as a eucrite and SNC (martian) orthopyroxenite ALH84001 was misclassified as a diogenite. In classifying meteorites we find what we expect: we pigeonhole meteorites into known categories most of which were derived from the more common asteroidal meteorites. But the examples of EET8752 and ALH84001 remind us that planets are more complex than asteroids and exhibit a wider variety of rock types. We should expect variety in planetary meteorites and we need to know how to recognize them when we have them. Our intent here is to show that our asteroidal perspective is inappropriate for planetary meteorites.

45 CFR 674.4 - Restrictions on collection of meteorites in Antarctica.

Science.gov (United States)

2010-10-01

... Antarctica. 674.4 Section 674.4 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION ANTARCTIC METEORITES § 674.4 Restrictions on collection of meteorites in Antarctica. No person may collect meteorites in Antarctica for other than scientific research purposes. ...

Natural occurrence of pure nano-polycrystalline diamond from impact crater

Science.gov (United States)

Ohfuji, Hiroaki; Irifune, Tetsuo; Litasov, Konstantin D.; Yamashita, Tomoharu; Isobe, Futoshi; Afanasiev, Valentin P.; Pokhilenko, Nikolai P.

2015-10-01

Consolidated bodies of polycrystalline diamond with grain sizes less than 100 nm, nano-polycrystalline diamond (NPD), has been experimentally produced by direct conversion of graphite at high pressure and high temperature. NPD has superior hardness, toughness and wear resistance to single-crystalline diamonds because of its peculiar nano-textures, and has been successfully used for industrial and scientific applications. Such sintered nanodiamonds have, however, not been found in natural mantle diamonds. Here we identified natural pure NPD, which was produced by a large meteoritic impact about 35 Ma ago in Russia. The impact diamonds consist of well-sintered equigranular nanocrystals (5-50 nm), similar to synthetic NPD, but with distinct [111] preferred orientation. They formed through the martensitic transformation from single-crystal graphite. Stress-induced local fragmentation of the source graphite and subsequent rapid transformation to diamond in the limited time scale result in multiple diamond nucleation and suppression of the overall grain growth, producing the unique nanocrystalline texture of natural NPD. A huge amount of natural NPD is expected to be present in the Popigai crater, which is potentially important for applications as novel ultra-hard material.

A recent meteorite shower in Antarctica with an unusual orbital history

Science.gov (United States)

Benoit, P. H.; Sears, D. W. G.

1993-01-01

The Antarctic meteorite collection has proved to be a source of many important discoveries, including a number of previously unknown or very rare meteorite types. A thermoluminescence (TL) survey of meteorite samples recovered by the 1988/89 European expedition and pre-1988 American expeditions to the Allan Hills Main blue ice field resulted in the discovery of 15 meteorites with very high TL levels (greater than 100 krad at 250 C in the glow curve). It is likely that these samples are fragments of a single meteoroid body which: (1) fell very recently and (2) experienced a decrease in orbital perihelia from greater than or equal to 1.1 AU to 1 AU within the last 10(exp 5) yr. Carbon-14 data for two of the samples confirm their young terrestrial age compared to most Antarctic meteorites. Studies of the cosmogenic isotopes in at least one non-Antarctic meteorite which also has very high natural TL, Jilin, indicate that the meteorite experienced a multi-stage irradiation history, the most recent stage being 0.4 Ma in duration following a major break-up of the object. These meteorites, and the few equivalent modern falls, are the only documented samples from bodies which were recently in Earth-approaching (Amor) orbits (i.e., with perihelion greater than 1.0 AU), as opposed to the Earth-crossing (Apollo) orbits which are the source of most other meteorites. Their rarity indicates that such rapid orbit changes are unusual for meteoroid bodies and may be the result of isolated, large break-up events.

The dimension added by 3D scanning and 3D printing of meteorites

Science.gov (United States)

de Vet, S. J.

2016-01-01

An overview for the 3D photodocumentation of meteorites is presented, focussing on two 3D scanning methods in relation to 3D printing. The 3D photodocumention of meteorites provides new ways for the digital preservation of culturally, historically or scientifically unique meteorites. It has the potential for becoming a new documentation standard of meteorites that can exist complementary to traditional photographic documentation. Notable applications include (i.) use of physical properties in dark flight-, strewn field-, or aerodynamic modelling; (ii.) collection research of meteorites curated by different museum collections, and (iii.) public dissemination of meteorite models as a resource for educational users. The possible applications provided by the additional dimension of 3D illustrate the benefits for the meteoritics community.

Comets, Carbonaceous Meteorites, and the Origin of the Biosphere

Science.gov (United States)

Hoover, Richard B.

2007-01-01

Evidence for indigenous microfossils in carbonaceous meteorites suggests that the paradigm of the endogenous origin of life on Earth should be reconsidered. It is now widely accepted that comets and carbonaceous meteorites played an important role in the delivery of water, organics and life critical biogenic elements to the early Earth and facilitated the origin and evolution of the Earth's Biosphere. However; the detection of embedded microfossils and mats in carbonaceous meteorites implies that comets and meteorites may have played a direct role in the delivery of intact microorganisms and that the Biosphere may extend far into the Cosmos. Recent space observations have found the nuclei of comets to have very low albedos (approx.0.03) and. these jet-black surfaces become very hot (T approx. 400 K) near perihelion. This paper reviews recent observational data-on comets and suggests that liquid water pools could exist in cavities and fissures between the internal ices and rocks and the exterior carbonaceous crust. The presence of light and liquid water near the surface of the nucleus enhances the possibility that comets could harbor prokaryotic extremophiles (e.g., cyanobacteria) capable of growth over a wide range of temperatures. The hypothesis that comets are the parent bodies of the CI1 and the CM2 carbonaceous meteorites is advanced. Electron microscopy images will be presented showing forms interpreted as indigenous-microfossils embedded' in freshly. fractured interior surfaces of the Orgueil (CI1) and Murchison (CM2) meteorites. These forms are consistent in size and morphologies with known morphotypes of all five orders of Cyanobacteriaceae: Energy Dispersive X-ray Spectroscopy (EDS) elemental data shows that the meteoritic forms have anomalous C/O; C/N; and C/S as compared with modern extremophiles and cyanobacteria. These images and spectral data indicate that the clearly biogenic and embedded remains cannot be interpreted as recent biological

Low-velocity impact cratering experiments in granular slopes

Science.gov (United States)

Hayashi, Kosuke; Sumita, Ikuro

2017-07-01

Low-velocity impact cratering experiments are conducted in sloped granular targets to study the effect of the slope angle θ on the crater shape and its scales. We use two types of granular matter, sand and glass beads, former of which has a larger friction coefficient μs = tanθr , where θr is the angle of repose. Experiments show that as θ increases, the crater becomes shallower and elongated in the direction of the slope. Furthermore the crater floor steepens in the upslope side and a thick rim forms in the downslope side, thus forming an asymmetric profile. High-speed images show that these features are results of ejecta being dispersed farther towards the downslope side and the subsequent avalanche which buries much of the crater floor. Such asymmetric ejecta dispersal can be explained by combining the Z-model and a ballistic model. Using the topographic maps of the craters, we classify crater shape regimes I-III, which transition with increasing θ : a full-rim crater (I), a broken-rim crater (II), and a depression (III). The critical θ for the regime transitions are larger for sand compared to glass beads, but collapse to close values when we use a normalized slope θ^ = tanθ / tanθr . Similarly we derive θ^-dependences of the scaled crater depth, length, width and their ratios which collapse the results for different targets and impact energies. We compare the crater profiles formed in our experiments with deep craters on asteroid Vesta and find that some of the scaled profiles nearly overlap and many have similar depth / length ratios. This suggests that these Vestan craters may also have formed in the gravity regime and that the formation process can be approximated by a granular flow with a similar effective friction coefficient.

Moon - 'Ghost' craters formed during Mare filling.

Science.gov (United States)

Cruikshank, D. P.; Hartmann, W. K.; Wood, C. A.

1973-01-01

This paper discusses formation of 'pathological' cases of crater morphology due to interaction of craters with molten lavas. Terrestrial observations of such a process are discussed. In lunar maria, a number of small impact craters (D less than 10 km) may have been covered by thin layers of fluid lavas, or formed in molten lava. Some specific lunar examples are discussed, including unusual shallow rings resembling experimental craters deformed by isostatic filling.

A complex of meteorite-forming bodies (the Innisfree - Ridgedale family).

Science.gov (United States)

Shestaka, I. S.

1994-12-01

For the first time a swarm of meteorite-forming bodies was identified. Yearly this swarm's orbit approaches the Earth's orbit in early February. This swarm contains the Innisfree and Ridgedale fireballs, 9 small meteoric swarms, several asteroids and 12 fireballs photographed by the cameras of the Prairie Network and Canadian Meteorite Observation and Discovery Project. The discovery of this complex, intensive bombardments of the Moon's surface recorded by means of seismographs left on the Moon, the analysis of the time distributions of meteorite falls on the Earth and other established facts confirm the existence of swarms of meteorite-forming bodies which are crossing the Earth's orbit.

57Fe Moessbauer Spectroscopy Studies of Meteorites: Implications for Weathering Rates, Meteorite Flux, and Early Solar System Processes

International Nuclear Information System (INIS)

Bland, P. A.; Berry, F. J.; Jull, A. J. T.; Smith, T. B.; Bevan, A. W. R.; Cadogan, J. M.; Sexton, A. S.; Franchi, L. A.; Pillinger, C. T.

2002-01-01

Ordinary chondrite finds, terrestrial age dated using 14 C analyses, from different meteorite accumulation sites, have been examined by Moessbauer spectroscopy to quantitatively determine terrestrial oxidation. We observe differences in weathering rates between sites, and also between different chondrite groups. A comparison of weathering over time, and its effect in 'eroding' meteorites, together with the number and mass distribution of meteorites in each region, enables us to derive estimates of the number of meteorite falls over a given mass per year. Studies of how the oxygen isotopic composition of samples varies with weathering indicate that incipient alteration may occur without a pronounced isotopic effect, possibly due to weathering of silicates to topotactically oriented smectite confined spaces where the water volume is limited. This finding has profound implications for the use of oxygen isotopes as a tool in understanding water-rock interaction. It also may reconcile previously contradictory data regarding the nebular or asteroidal location of pre-terrestrial aqueous alteration. Finally, Moessbauer spectroscopy is also found to be a useful tool in determining mineral abundance in carbonaceous chondrites, where a fine-grained matrix makes traditional approaches inapplicable. Again, the results have implications for the modification of chondritic materials in the early solar system.

The radiation age of meteorites; L'age des meteorites; Opredelenie vozrasta meteoritov s pomoshch'yu radiatsii; Edad de los meteoritos

Energy Technology Data Exchange (ETDEWEB)

Goebel, K; Schmidlin, P [European Organisation for Nuclear Research, Geneva (Switzerland)

1962-01-15

Radioisotopes produced by cosmic radiation in meteorites while travelling through space can be used to trace the history of these meteorites. The radioisotopes and the accumulated daughter-elements in the meteorite must be determined in order to evaluate how long the meteorite was exposed to cosmic radiation. (It must be assumed for this calculation that the flux of the cosmic radiation is constant with time.) Most often gaseous isotopes have been used for these measurements as they can be easily separated from the meteoric substance. In the reported work tritium and argon have been mainly used. From the ratio H{sup 3}/He{sup 3}, radiation ages from a few millions to several hundred millions of years have been found. The recent measurements made at the European Organisation for Nuclear Research (CERN) agree in principle with results from other sources. The probable errors from diffusion-losses of gas and the influence of shielding in the pre-atmospheric meteorite are discussed in the paper. By taking into consideration the measured cross-section for tritium production in the elements which form the meteorite, the values of the cosmic-ray flux in outer space can be determined. (author) [French] Les radioisotopes produits par les rayonnements cosmiques dans les meteorites circulant dans l'espace peuvent servir a reconstituer l'histoire de ces corps. Il faut mesurer les radioisotopes et les produits de filiation accumules dans la meteorite pour evaluer le temps pendant lequel la meteorite a ete exposee aux rayonnements cosmiques. (On considere alors que le flux des rayonnements cosmiques ne varie pas dans le temps.) Pour ces mesures, on se fonde le plus souvent sur les isotopes gazeux parce qu'il est facile de les separer de la substance meteorique. Dans les recherches qui font l'objet du present memoire, il s'agissait surtout du tritium et de l'argon. En partant du rapport {sup 3}H/{sup 3}He, on a pu evaluer des ages allant de quelques millions a plusieurs centaines

Expected Geochemical and Mineralogical Properties of Meteorites from Mercury: Inferences from Messenger Data

Science.gov (United States)

McCubbin, F. M.; McCoy, T. J.

2016-01-01

Meteorites from the Moon, Mars, and many types of asteroid bodies have been identified among our global inventory of meteorites, however samples of Mercury and Venus have not been identified. The absence of mercurian and venusian meteorites could be attributed to an inability to recognize them in our collections due to a paucity of geochemical information for Venus and Mercury. In the case of mercurian meteorites, this possibility is further supported by dynamical calculations that suggest mercurian meteorites should be present on Earth at a factor of 2-3 less than meteorites from Mars [1]. In the present study, we focus on the putative mineralogy of mercurian meteorites using data obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which has provided us with our first quantitative constraints on the geochemistry of planet Mercury. We have used the MESSENGER data to compile a list of mineralogical and geochemical characteristics that a meteorite from Mercury is likely to exhibit.

Meteorite Fall Detection and Analysis via Weather Radar: Worldwide Potential for Citizen Science

Science.gov (United States)

Fries, M.; Bresky, C.; Laird, C.; Reddy, V.; Hankey, M.

2017-12-01

Meteorite falls can be detected using weather radars, facilitating rapid recovery of meteorites to minimize terrestrial alteration. Imagery from the US NEXRAD radar network reveals over two dozen meteorite falls where meteorites have been recovered, and about another dozen that remain unrecovered. Discovery of new meteorite falls is well suited to "citizen science" and similar outreach activities, as well as automation of computational components into internet-based search tools. Also, there are many more weather radars employed worldwide than those in the US NEXRAD system. Utilization of weather radars worldwide for meteorite recovery can not only expand citizen science opportunities but can also lead to significant improvement in the number of freshly-fallen meteorites available for research. We will discuss the methodologies behind locating and analyzing meteorite falls using weather radar, and how to make them available for citizen science efforts. An important example is the Aquarius Project, a Chicago-area consortium recently formed with the goal of recovering meteorites from Lake Michigan. This project has extensive student involvement geared toward development of actual hardware for recovering meteorites from the lake floor. Those meteorites were identified in weather radar imagery as they fell into the lake from a large meteor on 06 Feb 2017. Another example of public interaction is the meteor detection systems operated by the American Meteor Society (AMS). The AMS website has been developed to allow public reporting of meteors, effectively enabling citizen science to locate and describe significant meteor events worldwide.

Determination of elemental abundances in impact materials by micro-PIXE and micro-SRXRF methods

International Nuclear Information System (INIS)

Uzonyi, I.; Szabo, Gy.; Kiss, A.Z.; Szoeoer, Gy.; Rozsa, P.

2004-01-01

The most famous and well-preserved meteorite crater in the world is the Barringer Meteor Crater (Arizona, USA). The meteorite is supposed to be a fragment of a small asteroid of our solar system. During the impact event the matter of the projectile mixed with that of the target rocks forming breccias, slag and spherules. For the non-destructive characterization of the impact materials a combined micro-PIXE and micro-SRXRF technique was applied. (N.T.)

Investigations of Ceres's Craters with Straightened Rim

Science.gov (United States)

Frigeri, A.; De Sanctis, M. C.; Ammannito, E.; Raponi, A.; Formisano, M.; Ciarniello, M.; Magni, G.; Combe, J. P.; Marchi, S.; Raymond, C. A.; Schwartz, S. J.

2017-12-01

Dwarf planet Ceres hosts some geological features that are unique in the solar system because its composition, rich in aqueously-altered silicates, is usually found on full-size planets, whereas its mean radius is smaller than most natural satellites in the solar system. For example, the local high-albedo, carbonate-rich areas or faculaeare specific to Ceres; also, the absence of big impact crater structures is key to understand the overall mechanical behaviour of the Cerean crust. After the first findings of water ice occurring in the shadowed areas of craters on Ceres by the NASA/Dawn mission (1, 2), we analyzed the morphology of craters looking for features similar to the ones where the water ice composition has been detected analyzing the data from the VIR spectrometer (3). These craters fall outside of the family of polygonal craters which are mainly related to regional or global scale tectonics (4). We analyzed the morphology on the base of the global mosaic, the digital terrain model derived by using the stereo photogrammetry method and the single data frames of the Framing Camera. Our investigation started from crater Juling, which is characterized by a portion of the rim which forms a straight segment instead of a portion of a circle. This linear crater wall is also steep enough that it forms a cliff that is in the shadowed area in all images acquired by Dawn. Very smooth and bright deposits lay at the foot of this crater-wall cliff. Then, we identified several other craters, relatively fresh, with radius of 2 to 10 kilometers, showing one or two sectors of the crater-rim being truncated by a mass-wasting process, probably a rockfall. Our first analysis show that in the selected craters, the truncated sectors are always in the north-eastern sector of the rim for the craters in the southern hemisphere. Conversely, the craters on the northern hemisphere exhibit a truncated rim in their south-eastern sector. Although a more detailed analysis is mandatory

Age determination of meteorites using radioactive nuclides

International Nuclear Information System (INIS)

Tanimizu, Masaharu

2002-01-01

Recently, the precise isotope ratios of some refractory elements in meteorites have been reported using inductively coupled plasma mass spectrometry. The in situ decay of 182 Hf (T 1/2 =9 Myr), which was produced at the latest nucleosynthesis, is recognized in many meteorites as isotopic anomalies of its daughter isotope, 182 W. The degrees of relative 182 W isotopic deviation in extra-terrestrial and terrestrial silicate samples vary from +0.3% to ±0% related to the size of their parent bodies. One ready interpretation of its correlation is the difference in timing of metal-silicate separation in the parent bodies. Between the earth and meteorite parent bodies, the difference is calculated to be about four times of the half-life of 182 Hf, equivalent to 36 Myr. (author)

Asteroid families from cratering: Detection and models

Science.gov (United States)

Milani, A.; Cellino, A.; Knežević, Z.; Novaković, B.; Spoto, F.; Paolicchi, P.

2014-07-01

A new asteroid families classification, more efficient in the inclusion of smaller family members, shows how relevant the cratering impacts are on large asteroids. These do not disrupt the target, but just form families with the ejecta from large craters. Of the 12 largest asteroids, 8 have cratering families: number (2), (4), (5), (10), (87), (15), (3), and (31). At least another 7 cratering families can be identified. Of the cratering families identified so far, 7 have >1000 members. This imposes a remarkable change from the focus on fragmentation families of previous classifications. Such a large dataset of asteroids believed to be crater ejecta opens a new challenge: to model the crater and family forming event(s) generating them. The first problem is to identify which cratering families, found by the similarity of proper elements, can be formed at once, with a single collision. We have identified as a likely outcome of multiple collisions the families of (4), (10), (15), and (20). Of the ejecta generated by cratering, only a fraction reaches the escape velocity from the surviving parent body. The distribution of velocities at infinity, giving to the resulting family an initial position and shape in the proper elements space, is highly asymmetric with respect to the parent body. This shape is deformed by the Yarkovsky effect and by the interaction with resonances. All the largest asteroids have been subjected to large cratering events, thus the lack of a family needs to be interpreted. The most interesting case is (1) Ceres, which is not the parent body of the nearby family of (93). Two possible interpretations of the low family forming efficiency are based on either the composition of Ceres with a significant fraction of ice, protected by a thin crust, or with the larger escape velocity of ~500 m/s.

The Global Contribution of Secondary Craters on the Icy Satellites

Science.gov (United States)

Hoogenboom, T.; Johnson, K. E.; Schenk, P.

2014-12-01

At present, surface ages of bodies in the Outer Solar System are determined only from crater size-frequency distributions (a method dependent on an understanding of the projectile populations responsible for impact craters in these planetary systems). To derive accurate ages using impact craters, the impactor population must be understood. Impact craters in the Outer Solar System can be primary, secondary or sesquinary. The contribution of secondary craters to the overall population has recently become a "topic of interest." Our objective is to better understand the contribution of dispersed secondary craters to the small crater populations, and ultimately that of small comets to the projectile flux on icy satellites in general. We measure the diameters of obvious secondary craters (determined by e.g. irregular crater shape, small size, clustering) formed by all primary craters on Ganymede for which we have sufficiently high resolution data to map secondary craters. Primary craters mapped range from approximately 40 km to 210 km. Image resolution ranges from 45 to 440 m/pixel. Bright terrain on Ganymede is our primary focus. These resurfaced terrains have relatively low crater densities and serve as a basis for characterizing secondary populations as a function of primary size on an icy body for the first time. Although focusing on Ganymede, we also investigate secondary crater size, frequency, distribution, and formation, as well as secondary crater chain formation on icy satellites throughout the Saturnian and Jovian systems principally Rhea. We compare our results to similar studies of secondary cratering on the Moon and Mercury. Using Galileo and Voyager data, we have identified approximately 3,400 secondary craters on Ganymede. In some cases, we measured crater density as a function of distance from a primary crater. Because of the limitations of the Galileo data, it is necessary to extrapolate from small data sets to the global population of secondary craters

Impact cratering experiments in Bingham materials and the morphology of craters on Mars and Ganymede

Science.gov (United States)

Fink, J. H.; Greeley, R.; Gault, D. E.

1982-01-01

Results from a series of laboratory impacts into clay slurry targets are compared with photographs of impact craters on Mars and Ganymede. The interior and ejecta lobe morphology of rampart-type craters, as well as the progression of crater forms seen with increasing diameter on both Mars and Ganymede, are equalitatively explained by a model for impact into Bingham materials. For increasing impact energies and constant target rheology, laboratory craters exhibit a morphologic progression from bowl-shaped forms that are typical of dry planetary surfaces to craters with ejecta flow lobes and decreasing interior relief, characteristic of more volatile-rich planets. A similar sequence is seen for uniform impact energy in slurries of decreasing yield strength. The planetary progressions are explained by assuming that volatile-rich or icy planetary surfaces behave locally in the same way as Bingham materials and produce ejecta slurries with yield strenghs and viscosities comparable to terrestrial debris flows. Hypothetical impact into Mars and Ganymede are compared, and it is concluded that less ejecta would be produced on Ganymede owing to its lower gravitational acceleration, surface temperature, and density of surface materials.

Technical problems and future cratering experiments

Energy Technology Data Exchange (ETDEWEB)

Knox, J B [Lawrence Radiation Laboratory, Livermore, CA (United States)

1969-07-01

This paper reviews some of the key technical problems that remain to be solved in nuclear cratering technology. These include: (1) developing a broader understanding of the effects that material properties and water content of the earth materials around the shot have on cratering behavior, (2) extending the experimental investigation of retarc formation to include intermediate yields and various materials, and (3) improving our ability to predict the escape of radioactive material to the atmosphere to form the cloud source responsible for fallout. The formation processes of ejecta craters, retarcs, and subsidence craters are described in the light of our present understanding, and the major gaps in our understanding are indicated. Methods of calculating crater and retarc formation are discussed, with particular reference to the input information needed. Methods for calculating fallout are presented, and their shortcomings are discussed. A preliminary analysis of the safety factors associated with the presently proposed nuclear excavation concepts is presented. (author)

Technical problems and future cratering experiments

International Nuclear Information System (INIS)

Knox, J.B.

1969-01-01

This paper reviews some of the key technical problems that remain to be solved in nuclear cratering technology. These include: (1) developing a broader understanding of the effects that material properties and water content of the earth materials around the shot have on cratering behavior, (2) extending the experimental investigation of retarc formation to include intermediate yields and various materials, and (3) improving our ability to predict the escape of radioactive material to the atmosphere to form the cloud source responsible for fallout. The formation processes of ejecta craters, retarcs, and subsidence craters are described in the light of our present understanding, and the major gaps in our understanding are indicated. Methods of calculating crater and retarc formation are discussed, with particular reference to the input information needed. Methods for calculating fallout are presented, and their shortcomings are discussed. A preliminary analysis of the safety factors associated with the presently proposed nuclear excavation concepts is presented. (author)

Cratering statistics on asteroids: Methods and perspectives

Science.gov (United States)

Chapman, C.

2014-07-01

Crater size-frequency distributions (SFDs) on the surfaces of solid-surfaced bodies in the solar system have provided valuable insights about planetary surface processes and about impactor populations since the first spacecraft images were obtained in the 1960s. They can be used to determine relative age differences between surficial units, to obtain absolute model ages if the impactor flux and scaling laws are understood, to assess various endogenic planetary or asteroidal processes that degrade craters or resurface units, as well as assess changes in impactor populations across the solar system and/or with time. The first asteroid SFDs were measured from Galileo images of Gaspra and Ida (cf., Chapman 2002). Despite the superficial simplicity of these studies, they are fraught with many difficulties, including confusion by secondary and/or endogenic cratering and poorly understood aspects of varying target properties (including regoliths, ejecta blankets, and nearly-zero-g rubble piles), widely varying attributes of impactors, and a host of methodological problems including recognizability of degraded craters, which is affected by illumination angle and by the ''personal equations'' of analysts. Indeed, controlled studies (Robbins et al. 2014) demonstrate crater-density differences of a factor of two or more between experienced crater counters. These inherent difficulties have been especially apparent in divergent results for Vesta from different members of the Dawn Science Team (cf. Russell et al. 2013). Indeed, they have been exacerbated by misuse of a widely available tool (Craterstats: hrscview.fu- berlin.de/craterstats.html), which incorrectly computes error bars for proper interpretation of cumulative SFDs, resulting in derived model ages specified to three significant figures and interpretations of statistically insignificant kinks. They are further exacerbated, and for other small-body crater SFDs analyzed by the Berlin group, by stubbornly adopting

Catalogue of meteorites from South America

CERN Document Server

Acevedo, Rogelio Daniel; García, Víctor Manuel

2014-01-01

The first Catalogue of Meteorites from South America includes new specimens never previously reported, while doubtful cases and pseudometeorites have been deliberately omitted.The falling of these objects is a random event, but the sites where old meteorites are found tend to be focused in certain areas, e.g. in the deflation surfaces in Chile's Atacama Desert, due to favorable climate conditions and ablation processes.Our Catalogue provides basic information on each specimen like its provenance and the place where it was discovered (in geographic co-ordinates and with illustrative maps), its

Weathering Profiles in Phosphorus-Rich Rocks at Gusev Crater, Mars, Suggest Dissolution of Phosphate Minerals into Potentially Habitable Near-Neutral Waters.

Science.gov (United States)

Adcock, Christopher T; Hausrath, Elisabeth M

2015-12-01

Abundant evidence indicates that significant surface and near-surface liquid water has existed on Mars in the past. Evaluating the potential for habitable environments on Mars requires an understanding of the chemical and physical conditions that prevailed in such aqueous environments. Among the geological features that may hold evidence of past environmental conditions on Mars are weathering profiles, such as those in the phosphorus-rich Wishstone-class rocks in Gusev Crater. The weathering profiles in these rocks indicate that a Ca-phosphate mineral has been lost during past aqueous interactions. The high phosphorus content of these rocks and potential release of phosphorus during aqueous interactions also make them of astrobiological interest, as phosphorus is among the elements required for all known life. In this work, we used Mars mission data, laboratory-derived kinetic and thermodynamic data, and data from terrestrial analogues, including phosphorus-rich basalts from Idaho, to model a conceptualized Wishstone-class rock using the reactive transport code CrunchFlow. Modeling results most consistent with the weathering profiles in Wishstone-class rocks suggest a combination of chemical and physical erosion and past aqueous interactions with near-neutral waters. The modeling results also indicate that multiple Ca-phosphate minerals are likely in Wishstone-class rocks, consistent with observations of martian meteorites. These findings suggest that Gusev Crater experienced a near-neutral phosphate-bearing aqueous environment that may have been conducive to life on Mars in the past. Mars-Gusev Crater-Wishstone-Reactive transport modeling-CrunchFlow-Aqueous interactions-Neutral pH-Habitability.

Usability of small impact craters on small surface areas in crater count dating: Analysing examples from the Harmakhis Vallis outflow channel, Mars

Science.gov (United States)

Kukkonen, S.; Kostama, V.-P.

2018-05-01

The availability of very high-resolution images has made it possible to extend crater size-frequency distribution studies to small, deca/hectometer-scale craters. This has enabled the dating of small and young surface units, as well as recent, short-time and small-scale geologic processes that have occurred on the units. Usually, however, the higher the spatial resolution of space images is, the smaller area is covered by the images. Thus the use of single, very high-resolution images in crater count age determination may be debatable if the images do not cover the studied region entirely. Here we compare the crater count results for the floor of the Harmakhis Vallis outflow channel obtained from the images of the ConTeXt camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO). The CTX images enable crater counts for entire units on the Harmakhis Vallis main valley, whereas the coverage of the higher-resolution HiRISE images is limited and thus the images can only be used to date small parts of the units. Our case study shows that the crater count data based on small impact craters and small surface areas mainly correspond with the crater count data based on larger craters and more extensive counting areas on the same unit. If differences between the results were founded, they could usually be explained by the regional geology. Usually, these differences appeared when at least one cratering model age is missing from either of the crater datasets. On the other hand, we found only a few cases in which the cratering model ages were completely different. We conclude that the crater counts using small impact craters on small counting areas provide useful information about the geological processes which have modified the surface. However, it is important to remember that all the crater counts results obtained from a specific counting area always primarily represent the results from the counting area-not the whole

Two Martian Winters at Gusev Crater and Meridiani Planum: New Results From the MER Mossbauer Spectrometers

Science.gov (United States)

Klingelhoefer, Goestar; Morris, Richard V.; Schroeder, Christian; Rodionov, Daniel S.; Yen, Albert S.; Ming, Douglas W.; Cohen, Barbara A.; Fleischer, Iris; Mittlefehldt, David W.; McCoy, Tim;

Nevada Test Site craters used for astronaut training

Science.gov (United States)

Moore, H. J.

1977-01-01

Craters produced by chemical and nuclear explosives at the Nevada Test Site were used to train astronauts before their lunar missions. The craters have characteristics suitable for reconnaissance-type field investigations. The Schooner test produced a crater about 300 m across and excavated more than 72 m of stratigraphic section deposited in a fairly regular fashion so that systematic observations yield systematic results. Other features common on the moon, such as secondary craters and glass-coated rocks, are present at Schooner crater. Smaller explosive tests on Buckboard Mesa excavated rocks from three horizontal alteration zones within basalt flows so that the original sequence of the zones could be determined. One crater illustrated the characteristics of craters formed across vertical boundaries between rock units. Although the exercises at the Nevada Test Site were only a small part of the training of the astronauts, voice transcripts of Apollo missions 14, 16, and 17 show that the exercises contributed to astronaut performance on the moon.

Field Guide to Meteors and Meteorites

CERN Document Server

Norton, O. Richard

2008-01-01

Imagine the unique experience of being the very first person to hold a newly-found meteorite in your hand – a rock from space, older than Earth! "Weekend meteorite hunting" with magnets and metal detectors is becoming ever more popular as a pastime, but of course you can’t just walk around and pick up meteorites in the same way that you can pick up seashells on the beach. Those fragments that survived the intense heat of re-entry tend to disguise themselves as natural rocks over time, and it takes a trained eye – along with the information in this book – to recognize them. Just as amateur astronomers are familiar with the telescopes and accessories needed to study a celestial object, amateur meteoriticists have to use equipment ranging from simple hand lenses to microscopes to study a specimen, to identify its type and origins. Equipment and techniques are covered in detail here of course, along with a complete and fully illustrated guide to what you might find and where you might find it. In fact, th...

Coordinated In Situ Analyses of Organic Nanoglobules in the Sutter's Mill Meteorite

Science.gov (United States)

Nakamura--Messenger, K.; Messenger, S.; Keller, L. P.; Clemett, S. J.; Nguyen, A. N.; Gibson, E. K.

2013-01-01

The Sutter s Mill meteorite is a newly fallen carbonaceous chondrite that was collected and curated quickly after its fall [1]. Preliminary petrographic and isotopic investigations suggest affinities to the CM2 carbonaceous chondrites. The primitive nature of this meteorite and its rapid recovery provide an opportunity to investigate primordial solar system organic matter in a unique new sample. Organic matter in primitive meteorites and chondritic porous interplanetary dust particles (CP IDPs) is commonly enriched in D/H and N-15/N-14 relative to terrestrial values [2-4]. These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material [2]. Some meteorites and IDPs contain gm-size inclusions with extreme H and N isotopic anomalies [3-5], possibly due to preserved primordial organic grains. The abundance and isotopic composition of C in Sutter's Mill were found to be similar to the Tagish Lake meteorite [6]. In the Tagish Lake meteorite, the principle carriers of large H and N isotopic anomalies are sub-micron hollow organic spherules known as organic nanoglobules [7]. Organic nanoglobules are commonly distributed among primitive meteorites [8, 9] and cometary samples [10]. Here we report in-situ analyses of organic nano-globules in the Sutter's Mill meteorite using UV fluorescence imaging, Fourier-transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (STEM), NanoSIMS, and ultrafast two-step laser mass spectrometry (ultra-L2MS).

Asteroids, meteorites, and comets

CERN Document Server

Elkins-Tanton, Linda T

2010-01-01

Asteroids, Comets, and Meteorites provides students, researchers, and general readers with the most up-to-date information on this fascinating field. From the days of the dinosaurs to our modern environment, this book explores all aspects of these cosmic invaders.

Determining long-term regional erosion rates using impact craters

Science.gov (United States)

Hergarten, Stefan; Kenkmann, Thomas

2015-04-01

More than 300,000 impact craters have been found on Mars, while the surface of Moon's highlands is even saturated with craters. In contrast, only 184 impact craters have been confirmed on Earth so far with only 125 of them exposed at the surface. The spatial distribution of these impact craters is highly inhomogeneous. Beside the large variation in the age of the crust, consumption of craters by erosion and burial by sediments are the main actors being responsible for the quite small and inhomogeneous crater record. In this study we present a novel approach to infer long-term average erosion rates at regional scales from the terrestrial crater inventory. The basic idea behind this approach is a dynamic equilibrium between the production of new craters and their consumption by erosion. It is assumed that each crater remains detectable until the total erosion after the impact exceeds a characteristic depth depending on the crater's diameter. Combining this model with the terrestrial crater production rate, i.e., the number of craters per unit area and time as a function of their diameter, allows for a prediction of the expected number of craters in a given region as a function of the erosion rate. Using the real crater inventory, this relationship can be inverted to determine the regional long-term erosion rate and its statistical uncertainty. A limitation by the finite age of the crust can also be taken into account. Applying the method to the Colorado Plateau and the Deccan Traps, both being regions with a distinct geological history, yields erosion rates in excellent agreement with those obtained by other, more laborious methods. However, these rates are formally exposed to large statistical uncertainties due to the small number of impact craters. As higher crater densities are related to lower erosion rates, smaller statistical errors can be expected when large regions in old parts of the crust are considered. Very low long-term erosion rates of less than 4

Investigation of Secondary Craters in the Saturnian System

Science.gov (United States)

Hoogenboom, T.; Schenk, P.; White, O. L.

2012-03-01

To derive accurate ages using impact craters, the impact source must be determined. We investigate secondary crater size, frequency, distribution, formation, and crater chain formation on icy satellites throughout the Jupiter and Saturn systems.

U-Pb studies of the Appley Bridge meteorite

International Nuclear Information System (INIS)

Gale, N.H.; Arden, J.W.; Hutchinson, R.

1979-01-01

The U and Pb concentration in samples from the interior of the 10.9 kg stone BM 1920, 40 (British Museum), the isotopic composition of lead, a lead-lead diagram for whole meteorite samples of Appley Bridge, and a U-Pb concordia diagram for whole meteorite samples of Appley Bridge from different measurements are treated. (HK) 891 HK/HK 892 MB [de

An Anomalous Basaltic Meteorite from the Innermost Main Belt

Czech Academy of Sciences Publication Activity Database

Bland, P.A.; Spurný, Pavel; Towner, M.C.; Bevan, A.W.R.; Singleton, A.T.; Bottke jr., W.F.; Greenwood, R.C.; Chesley, S.R.; Shrbený, Lukáš; Borovička, Jiří; Ceplecha, Zdeněk; McClafferty, T.; Vaughan, D.; Benedix, G.K.; Deacon, G.; Howard, K.T.; Franchi, I.A.; Hough, R.M.

2009-01-01

Roč. 325, č. 5947 (2009), s. 1525-1527 ISSN 0036-8075 R&D Projects: GA ČR GA205/08/0411 Institutional research plan: CEZ:AV0Z10030501 Keywords : meteorites * meteorite fall Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 29.747, year: 2009

Cratering Equations for Zinc Orthotitanate Coated Aluminum

Science.gov (United States)

Hyde, James; Christiansen, Eric; Liou, Jer-Chyi; Ryan, Shannon

2009-01-01

The final STS-125 servicing mission (SM4) to the Hubble Space Telescope (HST) in May of 2009 saw the return of the 2nd Wide Field Planetary Camera (WFPC2) aboard the shuttle Discovery. This hardware had been in service on HST since it was installed during the SM1 mission in December of 1993 yielding one of the longest low Earth orbit exposure times (15.4 years) of any returned space hardware. The WFPC2 is equipped with a 0.8 x 2.2 m radiator for thermal control of the camera electronics (Figure 1). The space facing surface of the 4.1 mm thick aluminum radiator is coated with Z93 zinc orthotitanate thermal control paint with a nominal thickness of 0.1 0.2 mm. Post flight inspections of the radiator panel revealed hundreds of micrometeoroid/orbital debris (MMOD) impact craters ranging in size from less than 300 to nearly 1000 microns in diameter. The Z93 paint exhibited large spall areas around the larger impact sites (Figure 2) and the craters observed in the 6061-T651 aluminum had a different shape than those observed in uncoated aluminum. Typical hypervelocity impact craters in aluminum have raised lips around the impact site. The craters in the HST radiator panel had suppressed crater lips, and in some cases multiple craters were present instead of a single individual crater. Humes and Kinard observed similar behavior after the WFPC1 post flight inspection and assumed the Z93 coating was acting like a bumper in a Whipple shield. Similar paint behavior (spall) was also observed by Bland2 during post flight inspection of the International Space Station (ISS) S-Band Antenna Structural Assembly (SASA) in 2008. The SASA, with similar Z93 coated aluminum, was inspected after nearly 4 years of exposure on the ISS. The multi-crater phenomena could be a function of the density, composition, or impact obliquity angle of the impacting particle. For instance, a micrometeoroid particle consisting of loosely bound grains of material could be responsible for creating the

Pancam Peek into 'Victoria Crater' (Stereo)

Science.gov (United States)

2006-01-01

[figure removed for brevity, see original site] Left-eye view of a stereo pair for PIA08776 [figure removed for brevity, see original site] Right-eye view of a stereo pair for PIA08776 A drive of about 60 meters (about 200 feet) on the 943rd Martian day, or sol, of Opportunity's exploration of Mars' Meridiani Planum region (Sept. 18, 2006) brought the NASA rover to within about 50 meters (about 160 feet) of the rim of 'Victoria Crater.' This crater has been the mission's long-term destination for the past 21 Earth months. Opportunity reached a location from which the cameras on top of the rover's mast could begin to see into the interior of Victoria. This stereo anaglyph was made from frames taken on sol 943 by the panoramic camera (Pancam) to offer a three-dimensional view when seen through red-blue glasses. It shows the upper portion of interior crater walls facing toward Opportunity from up to about 850 meters (half a mile) away. The amount of vertical relief visible at the top of the interior walls from this angle is about 15 meters (about 50 feet). The exposures were taken through a Pancam filter selecting wavelengths centered on 750 nanometers. Victoria Crater is about five times wider than 'Endurance Crater,' which Opportunity spent six months examining in 2004, and about 40 times wider than 'Eagle Crater,' where Opportunity first landed. The great lure of Victoria is the expectation that a thick stack of geological layers will be exposed in the crater walls, potentially several times the thickness that was previously studied at Endurance and therefore, potentially preserving several times the historical record.

Organic compounds in the Murchison meteorite.

Science.gov (United States)

Ponnamperuma, C.

1972-01-01

Impressive supporting evidence for the concept of the chemical evolution of life has appeared in the discovery of biologically important compounds in extraterrestrial samples. The approaches pursued to detect extraterrestrial organic compounds include the study of interstellar space by radioastronomy, the evaluation of the Apollo lunar samples, and the analysis of meteorites, both ancient and recent. It has been found that the clouds of gas in the interstellar medium contain a wide variety of molecules, most of which are organic in nature. The carbonaceous chondrites contain polymeric organic matter. Amino acids have been detected in the Murchison meteorite.

Galactic cosmic-ray-produced radionuclides in Antarctic meteorites and a lunar core

International Nuclear Information System (INIS)

Fox, R.L.

1987-01-01

Radionuclide depth effects in a meteorite, the history and pairing of Antarctic meteorites and processes on the lunar surface are discussed in six chapters. A depth profile of 26 Al, 10 Be and 53 Mn activities have been measured in eleven metal phase samples of the Antarctic meteorite ALHA78084 to determine the importance of the secondary cascade in producing these nuclides in a 30 centimeter diameter meteorite. The results show a buildup of lower energy reaction products and a flat profile for high energy reaction products with depth. The activity of 53 Mn has been measured as a function of depth in eleven soil samples from the lunar double drive tubes 15011/15010. The results agree within error with the previous results of Nishiizumi. These data are consistent with the previously published 26 Al results of the Battelle Northwest group which indicated a disturbed profile down to 17 g/cm 2 and an accumulation rate of 2 cm/My. Comparison with the gardening models of Arnold and Langevin and the local topography suggests such a continuous accumulation is the result of steady downslope transport of surface soil for 7 to 10 My at this site. The 53 Mn activity was determined in eleven samples in eight Allan Hills-80 Antarctic meteorites and one sample from an Elephant Moraine Antarctic meteorite. Mineralogic and field relation data suggest that Allan Hills meteorites to be two sets of paired falls. The 53 Mn results are consistent with the grouping of these meteorites as paired falls excluding the meteorite ALHA80127. comparison with future nuclear particle track work and results from the measurement of other cosmogenic nuclides will provide more definitive results

A schematic model of crater modification by gravity

Science.gov (United States)

Melosh, H. J.

1982-01-01

The morphology of craters found on planets and moons of the solar system is examined and a development model which can account for the observed crater characteristics is discussed. The prompt collapse of craters to form flat floors, terraced walls, and central peak structures is considered to be the result of an approximate Bingham plastic rheology of the material surrounding the crater. This rheology is induced dynamically by the strong incoherent acoustic 'noise' accompanying excavation of the crater. Central pits, peak rings, and other multiple symmetric-profile rings originate by oscillation of this fluid. Large craters with transient depths comparable to the lithosphere thickness are subject to collapse by fragmentation of the lithosphere as well as fluidization. The considered concepts are developed mathematically. A model emerges which appears capable of explaining most of the qualitative features of large impact structures.

Morphometry and Morphology of Fresh Craters on Titan

Science.gov (United States)

Kirk, R. L.; Wood, C. A.; Neish, C.; Lucas, A.; Hayes, A. G.; Cassini Radar Team

2011-12-01

Cassini RADAR imagery obtained on Titan flyby T77 revealed a 40-km diameter fresh impact crater at 11.6° N 44.6° W. This is only the 8th crater identified with high confidence (Wood et al., 2010, Icarus 206, 334), and the 3rd (after Sinlap D=79 km and Ksa D=30 km) for which the depth can be estimated by comparing the foreshortening of the near and far walls. This "autostereo" technique yields an estimated depth of 680 m. The T77 image forms a stereo pair with the T17 discovery image of Ksa from which we estimate the depth of Ksa at 750-800 m, in close agreement with SARTopo data. The depth of Sinlap is 760 m based on SARTopo. Depth-diameter ratios for these craters thus range from 0.01 to 0.025 and the depths are comparable to but 200-400 m shallower than fresh craters of the same size on Ganymede (Bray et al., 2008, Met. Planet Sci. 43, 1979). The depth differences could be explained by initial crater morphometry, by relaxation in a different thermal environment, or (perhaps most plausibly given the bland floors of even the freshest Titan craters) to sedimentary infill. In contrast, the 18x36 km elliptical depression at Sotra Facula is much deeper than Ganymede craters of similar size (d=1500 m from stereo), supporting the conclusion that it is not an impact crater. All three craters exhibit a relatively radar-bright annulus around the outer edge of the floor, possibly as the result of mass wasting of blocky materials from the crater walls. The central part of each crater is darker. The central darker floor of the new crater is symmetrical and featureless, whereas Ksa has a bright central ring 7 km in diameter. Stereo spot heights indicate the ring is 350±100 m above the outer floor. This height is in close agreement with the scaling for Ganymede crater central peaks from Bray et al. (2008). The darker floor area of Sinlap is substantially asymmetrical with a small bright central spot whose elevation is unknown. The new crater has continuous, radar

Crater topography on Titan: Implications for landscape evolution

Science.gov (United States)

Neish, C.; Kirk, R.; Lorenz, R.; Bray, V.; Schenk, P.; Stiles, B.; Turtle, E.; Cassini Radar Team

2012-04-01

Unique among the icy satellites, Titan’s surface shows evidence for extensive modification by fluvial and aeolian erosion, which act to change the topography of its surface over time. Quantifying the extent of this landscape evolution is difficult, since the original, ‘non-eroded’ surface topography is generally unknown. However, fresh craters on icy satellites have a well-known shape and morphology, which has been determined from extensive studies on the airless worlds of the outer solar system (Schenk et al., 2004). By comparing the topography of craters on Titan to similarly sized, pristine analogues on airless bodies, we can obtain one of the few direct measures of the amount of erosion that has occurred on Titan. Cassini RADAR has imaged >30% of the surface of Titan, and more than 60 potential craters have been identified in this data set (Wood et al., 2010; Neish and Lorenz, 2012). Topographic information for these craters can be obtained from a technique known as ‘SARTopo’, which estimates surface heights by comparing the calibration of overlapping synthetic aperture radar (SAR) beams (Stiles et al., 2009). We present topography data for several craters on Titan, and compare the data to similarly sized craters on Ganymede, for which topography has been extracted from stereo-derived digital elevation models (Bray et al., 2012). We find that the depths of craters on Titan are generally within the range of depths observed on Ganymede, but several hundreds of meters shallower than the average (Fig. 1). A statistical comparison between the two data sets suggests that it is extremely unlikely that Titan’s craters were selected from the depth distribution of fresh craters on Ganymede, and that is it much more probable that the relative depths of Titan are uniformly distributed between ‘fresh’ and ‘completely infilled’. This is consistent with an infilling process that varies linearly with time, such as aeolian infilling. Figure 1: Depth of

Noble gases in ten stone meteorites from Antarctica

International Nuclear Information System (INIS)

Weber, H.W.; Schultz, L.

1980-01-01

The concentrations and isotopic composition of noble gases have been determined in all ten stone meteorites recovered in Antarctica during 1976-1977 by a U.S.-Japanese expedition. From a comparison of spallogenic and radiogenic gas components it is concluded that the chondrites Mt. Baldr (a) and Mt. Baldr (b) belong to the same fall but that all other stone meteorites are individual finds. (orig.)

Express delivery of fossil meteorites from the inner asteroid belt to Sweden

Science.gov (United States)

Nesvorný, David; Vokrouhlický, David; Bottke, William F.; Gladman, Brett; Häggström, Therese

2007-06-01

Our understanding of planet formation depends in fundamental ways on what we learn by analyzing the composition, mineralogy, and petrology of meteorites. Yet, it is difficult to deduce the compositional and thermal gradients that existed in the solar nebula from the meteoritic record because, in most cases, we do not know where meteorites with different chemical and isotopic signatures originated. Here we developed a model that tracks the orbits of meteoroid-sized objects as they evolve from the ν secular resonance to Earth-crossing orbits. We apply this model to determining the number of meteorites accreted on the Earth immediately after a collisional disruption of a D˜200-km-diameter inner-main-belt asteroid in the Flora family region. We show that this event could produce fossil chondrite meteorites found in an ≈470 Myr old marine limestone quarry in southern Sweden, the L-chondrite meteorites with shock ages ≈470 Myr falling on the Earth today, as well as asteroid-sized fragments in the Flora family. To explain the measured short cosmic-ray exposure ages of fossil meteorites our model requires that the meteoroid-sized fragments were launched at speeds >500 m s -1 and/or the collisional lifetimes of these objects were much shorter immediately after the breakup event than they are today.

Neuschwanstein and Pribram: Two solitaire meteorites or members of a stream?

Science.gov (United States)

Oberst, J.; Spurny, P.; Heinlein, D.

2003-04-01

The fall of the Neuschwanstein enstatite chondrite EL6 at 20:20:17.7 UTC on April 6, 2002, in Southern Bavaria is well documented. Using photographic records obtained by the European Fireball Network (EN), the heliocentric orbit of the object before its collision with Earth could be determined [Spurny et al., Nature, submitted]. Surprisingly, its orbit is practically identical to that of another meteorite, which was photographed by the EN 43 years earlier: the Pribram H5-chondrite, which fell on April 7, 1959. The orbital elements are extremely similar indeed, as is indicated by a D-criterion of D=0.025. By analysis of the orbital elements of all available (approx. 200) ''meteorite candidates'', we estimate that the chances of finding two meteorites with orbital elements matching as well as in the case of Pribram and Neuschwanstein is 1:100,000. Therefore, we believe that the paired fall is not a coincidence and that the meteorites are members of a stream of objects. Considering Innisfree and Ridgedale, another paired fall, observed by the Canadian MORP (Meteorite Observation and Recovery Project), in 1977 and 1980 [Halliday, Icarus 69, 550-556, 1987], it appears that meteorite streams are not uncommon among Earth-approaching objects. On the basis of the observational efficiency of the EN, we estimate that the Pribram/Neuschwanstein meteorite stream contains approx. 10^9 members; all of them combined would form an asteroid with a minimum radius of 300m. From studies of cometary-type meteor streams it is known that these cometary stream members have separated from their parent body fairly recently. However, judging from the different classifications of the meteorites, and from their long cosmic exposure (Pribram has a cosmic ray age of 19 Million years) both, a common parent and a recent separation, are not very likely.

Comparisons of PGA and INAA in the analyses of meteorite samples

International Nuclear Information System (INIS)

Wee Boon Siong; Ebihara, M.; Abdul Khalik Wood

2010-01-01

Prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA) are suitable methods for multi-elemental determinations in various samples. These two methods are complementary because PGA is capable of analyzing most major and minor elements in rock samples whereas INAA is more superior in determining minor and trace elements. Both PGA and INAA are essential for the study of rare samples such as meteorites because of non-destructivity and relatively being free from contaminations. Samples for PGA can be reused for INAA, which help to reduce the sample usage. This project aims to utilize PGA and INAA techniques for comparative study and apply them to meteorites. In this study, 11 meteorite samples received from the Meteorite Working Group of NASA were analyzed. The Allende meteorite powder was included as quality control material. Results from PGA and INAA for Allende showed good agreement with literature values, signifying the reliabilities of these two methods. Elements Al, Ca, Mg, Mn, Na and Ti were determined by both methods and their results are compared. Comparison of PGA and INAA data using linear regression analysis showed correlations coefficients r 2 > 0.90 for Al, Ca, Mn and Ti, 0.85 for Mg, and 0.38 for Na. The PGA results for Na using 472 keV were less accurate due to the interference from the broad B peak. Therefore, Na results from INAA method are preferred. For other elements (Al, Ca, Mg, Mn and Ti), PGA and INAA results can be used as cross-reference for consistency. The PGA and INAA techniques have been applied to meteorite samples and results are comparable to literature values compiled from previously analyzed meteorites. In summary, both PGA and INAA methods give reasonably good agreement and are indispensable in the study of meteorites. (author)

Detection of lunar floor-fractured craters using machine learning methods

Science.gov (United States)

Thorey, C.

2015-10-01

About 200 Floor Fractured Craters (FFCs) have been identified by Schultz (1976) on the Moon, mainly around the lunar maria. These craters are a class of impact craters that are distinguished by having radi-ally and concentric floor-fractured networks and ab-normally shallow floors. In some cases, the uplift of the crater floor can be as large as 50% of the initial crater depth. These impact craters are interpreted to have undergone endogenous deformations after their formation.

Identification, testing, and analysis of a meteorite debris from jhelum, pakistan

International Nuclear Information System (INIS)

Kayani, S.

2012-01-01

In this research paper, X-ray diffraction (XRD) and X-ray fluorescence (XRF) spectrometry have been used to determine the mineralogical and elemental composition of a stone sample recovered from a location near village Lehri in district Jhelurn, Pakistan. The test data is compared with previous findings (as reported in literature and included in references) to identify this sample stone as part of a prehistoric meteorite ablation debris. Carbon content of a specimen of the meteorite debris has also been determined through combustion analysis. This carbon abundance has been compared with carbon wt% value of a certain type of meteorites to establ ish the origin and nature of the parent body of this particular meteorite debris. (author)

Simple Impact Crater Shapes From Shadows - The Sequel

Science.gov (United States)

Chappelow, J. E.

2008-12-01

At the last LPSC meeting I presented the outline of a method for determining simple impact crater shapes from shadows. In theory the shadow cast within a simple crater provides enough information to derive its cross-sectional shape from shadow measurements, at least to the maximum depth to which the shadow extends. Under certain simple assumptions, this can be done analytically. If the crater is conic-section - shaped, then it can be shown that the down-sun bound of any shadow cast within it is elliptical, with one axis along the direction of illumination and the other (perpendicular to it) of semi-length D/2 (where D is diameter). The properties of this shadow-ellipse can be related to the parameters of the crater shape conic-section, thus measurements of the shadow-ellipse yield not only crater depth and diameter but also the approximate crater shape, in terms of conic sections. The method also does not depend upon the shadow crossing near the crater center, which avoids a pitfall of older shadow measurement methods. The technique is also amenable to computer implementation, which has already been largely completed. Once computerized, crater measurements can be made rapidly and repeatably. The program reads in an image, its resolution, and the solar elevation and azimuth. The user then defines the crater rim by 'clicking' on three points, and the shadow ellipse by clicking on two more. The program calculates and outputs the diameter, the depth, and parameters describing the crater's approximating conic-section. It is highly applicable to situations where only single-image photography is available, for example MESSENGER flybys of Mercury. At the meeting I will present the finished math for this method and give some examples of its use.

The Boltysh crater record of rapid vegetation change during the Dan-C2 hyperthermal event.

Science.gov (United States)

Jolley, D. W.; Daly, R.; Gilmour, I.; Gilmour, M.; Kelley, S. P.

2012-04-01

Analysis of a cored borehole drilled through the sedimentary fill of the 24km wide Boltysh meteorite crater, Ukraine has yielded a unique, high resolution record spanning algae records. These records reflect environmental change from the K/Pg1 to the post Dan-C2 Danian. Leading into the CIE, warm temperate gymnosperm - angiosperm - fern communities are replaced by precipitation limited (winterwet) plant communities within the negative CIE. Winterwet plant communities dominate the negative CIE, but are replaced within the isotope recovery stage by warm temperate floras. These in turn give way to cooler temperate floras in the post positive CIE section of the uppermost crater fill. The distribution of temperate taxa about the negative CIE represents the broadest scale of oscillatory variation in the palynofloras. Shorter frequency oscillations are evident from diversity and botanical group distributions reflecting changes in moisture availability over several thousand years. Detailed analysis of variability within one of these oscillations records plant community cyclicity across the inception of the negative CIE. This short term cyclicity provides evidence that the replacement of warm termperate by winterwet floras occurred in a stepwise manner at the negative CIE suggesting cumulative atmospheric forcing. At <1mm scale, lamination within the negative CIE showed no obvious lithological or colour differences, and are not seasonal couplets. However, palynofloral analysis of laminations from within the negative CIE has yielded evidence of annual variation identifying the potential for recoding changes in 'paleoweather' across a major hyperthermal event. [1] Jolley, D. W. et al. (2010) Geology 38, 835-838.

The role of population in tracking meteorite falls in Africa

Science.gov (United States)

Khiri, F.; Ibhi, A.; Saint-Gerant, T.; Medjkane, M.; Ouknine, L.

2016-01-01

The 158 African meteorite falls recorded during the period 1801 to 2014, account for more than 12.3% of all meteorite falls known from the world. Their rate is variable in time and in space. The number of falls continues to grow since 1860. They are concentrated in countries which exhibit large population (mainly rural population) with an uniform distribution. Generally, the number of falls follows the increase of the population density (coefficient of correlation r = 0.98). The colonial phenomenon, the education of population in this field, the population lifestyle and the rural exodus, are also factors among others which could explain the variability of the recovery of meteorite falls in Africa. In this note, we try by a statistical study, to examine the role of the African population in tracking meteorite falls on this continent.

Dating the Martian meteorite Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.

Science.gov (United States)

Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J

2015-01-30

The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in

Moessbauer spectroscopy of the Soledade meteorite

International Nuclear Information System (INIS)

Paduani, Clederson; Peres, Carlos Ariel Samudio

2004-01-01

Full text: Since the early studies of the microstructure and chemical composition of meteorites the formation of magnetic phases have attracted the attention of metallurgists. Mostly metallic specimens presented high contents of nickel and iron as major constituents, and thus the Fe-Ni alloys formed under such special conditions have been the subject of several investigations with a variety of experimental techniques. This is not an easy task considering the weathering process and the distribution of oxides in the metallic matrix, which in some cases varies in composition from one region to another. In this work we applied the Moessbauer spectroscopy to study the iron-bearing phases detected in the meteorite called Soledade. Although no one knows precisely who and when this specimen was found, it received the name of the locality from where it proceeded near the city of Passo Fundo in the state of Rio Grande do Sul in Brazil. The first studies indicate that this metallic meteorite is an octahedrite, with polycrystalline troilite, cohenite, schreibersite and rhabdites as major constituents. It consists of a solid block weighing 68 kg, with an irregular form measuring about 36x22x16 cm. (author)

Shallow and deep fresh impact craters in Hesperia Planum, Mars

Science.gov (United States)

Mouginis-Mark, Peter J.; Hayashi, Joan N.

1993-01-01

The depths of 109 impact craters about 2-16 km in diameter, located on the ridged plains materials of Hesperia Planum, Mars, have been measured from their shadow lengths using digital Viking Orbiter images (orbit numbers 417S-419S) and the PICS computer software. On the basis of their pristine morphology (very fresh lobate ejecta blankets, well preserved rim crests, and lack of superposed impact craters), 57 of these craters have been selected for detailed analysis of their spatial distribution and geometry. We find that south of 30 deg S, craters less than 6.0 km in diameter are markedly shallower than similar-sized craters equatorward of this latitude. No comparable relationship is observed for morphologically fresh craters greater than 6.0 km diameter. We also find that two populations exist for older craters less than 6.0 km diameter. When craters that lack ejecta blankets are grouped on the basis of depth/diameter ratio, the deeper craters also typically lie equatorward of 30 S. We interpret the spatial variation in crater depth/diameter ratios as most likely due to a poleward increase in volatiles within the top 400 m of the surface at the times these craters were formed.

Optimizing laser crater enhanced Raman scattering spectroscopy

Science.gov (United States)

Lednev, V. N.; Sdvizhenskii, P. A.; Grishin, M. Ya.; Fedorov, A. N.; Khokhlova, O. V.; Oshurko, V. B.; Pershin, S. M.

2018-05-01

The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for L-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

3D structure of the Gusev Crater region

NARCIS (Netherlands)

van Kan - Parker, M.; Zegers, T.E.; kneissl, T.; Ivanov, B.; Neukum, G.; Foing, B.

2010-01-01

Gusev Crater lies within the Aeolis Quadrangle of Mars at the boundary between the northern lowlands and southern highlands. The ancient valley Ma'adim Vallis dissects the highlands south of Gusev Crater and is thought to have fed the crater with sediments.High Resolution Stereo Camera data and

Crater ejecta scaling laws: fundamental forms based on dimensional analysis

International Nuclear Information System (INIS)

Housen, K.R.; Schmidt, R.M.; Holsapple, K.A.

1983-01-01

A model of crater ejecta is constructed using dimensional analysis and a recently developed theory of energy and momentum coupling in cratering events. General relations are derived that provide a rationale for scaling laboratory measurements of ejecta to larger events. Specific expressions are presented for ejection velocities and ejecta blanket profiles in two limiting regimes of crater formation: the so-called gravity and strength regimes. In the gravity regime, ejectra velocities at geometrically similar launch points within craters vary as the square root of the product of crater radius and gravity. This relation implies geometric similarity of ejecta blankets. That is, the thickness of an ejecta blanket as a function of distance from the crater center is the same for all sizes of craters if the thickness and range are expressed in terms of crater radii. In the strength regime, ejecta velocities are independent of crater size. Consequently, ejecta blankets are not geometrically similar in this regime. For points away from the crater rim the expressions for ejecta velocities and thickness take the form of power laws. The exponents in these power laws are functions of an exponent, α, that appears in crater radius scaling relations. Thus experimental studies of the dependence of crater radius on impact conditions determine scaling relations for ejecta. Predicted ejection velocities and ejecta-blanket profiles, based on measured values of α, are compared to existing measurements of velocities and debris profiles

Extraterrestrial Amino Acids in the Almahata Sitta Meteorite

Science.gov (United States)

Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.

2010-01-01

Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, R-amino-n-butyric acid (beta-ABA), 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (D/L approximately 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other non-protein amino acids were also identified in the meteorite above background levels including alpha-aminoisobutyric acid (alpha-AIB), 4-amino-2- methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and alpha-AIB in Almahata Sitta are 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five carbon amino acids in Almahata Sitta compared to Cl, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC3 cooled to lower temperatures.

The enrichment of the ISM: Evolved stars and meteorites

Science.gov (United States)

Jura, M.

1995-01-01

Small inclusions (diameters ranging from 0.001 microns to 10 microns) of isotopically anomalous material within meteorites were almost certainly produced in mass-losing stars. These solid particles preserved their individual identities as they passed through the interstellar medium and the pre-solar nebular. The relationship between studies of meteorites and mass-losing red giants is explored.

Mars Methane at Gale Crater Shows Strong Seasonal Cycle: Updated Results from TLS-SAM on Curiosity

Science.gov (United States)

Webster, C. R.; Mahaffy, P. R.; Atreya, S. K.; Flesch, G.; Malespin, C.; McKay, C.; Martinez, G.; Moores, J.; Smith, C. L.; Martin-Torres, F. J.; Gomez-Elvira, J.; Zorzano, M. P.; Wong, M. H.; Trainer, M. G.; Eigenbrode, J. L.; Glavin, D. P.; Steele, A.; Archer, D., Jr.; Sutter, B.; Coll, P. J.; Freissinet, C.; Meslin, P. Y.; Pavlov, A.; Keymeulen, D.; Christensen, L. E.; Gough, R. V.; Schwenzer, S. P.; Navarro-Gonzalez, R.; Pla-García, J.; Rafkin, S. C.; Vicente-Retortillo, Á.; Kahanpää, H.; Viudez-Moreiras, D.; Smith, M. D.; Harri, A. M.; Genzer, M.; Hassler, D.; Lemmon, M. T.; Crisp, J. A.; Zurek, R. W.; Vasavada, A. R.

2017-12-01

In situ measurements of atmospheric methane have been made over a 5-year period at Gale Crater on Mars using the Tunable Laser Spectrometer (TLS) instrument in the Sample Analysis at Mars (SAM) suite on the Curiosity rover. We report two important observations: (i) a background level of mean value of 0.41 ±0.11 (2sem) that is about 5 times lower than some model predictions based on generation from UV degradation of micro-meteorites or interplanetary dust delivered to the martian surface; (ii) "spikes" of elevated levels of 7 ppbv attributed to episodic releases from small local sources, probably to the north of Gale crater1. Reports of plumes, patches or episodic releases of methane in the Martian atmosphere have to date eluded explanation in part because of their lack of repeatability in time or location. Our in situ measurements of the background methane levels exhibit a strong, repeatable seasonal variability. The amplitude of the observed seasonal cycle is 3 times greater than both that expected from the annual sublimation and freezing of polar carbon dioxide and that expected from methane production from ultraviolet (UV) degradation of exogenously-delivered surface material. The observed large seasonal variation in the background, and sporadic observations of higher pulses of 7 ppbv appear consistent with localized small sources of methane release from Martian surface reservoirs that may be occurring throughout the planet. We will present our updated data set, correlations of Mars methane with various other measurements from SAM, REMS, RAD and ChemCam instruments on Curiosity, as well as empirical models of UV surface insolation, and provide preliminary interpretation of results. 1 "Mars Methane Detection and Variability at Gale Crater", C. R. Webster et al., Science, 347, 415-417 (2015) and references therein. The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the

Meteorite Falls Observed by the Desert Fireball Network: An Update

Czech Academy of Sciences Publication Activity Database

Bland, P.A.; Spurný, Pavel; Shrbený, Lukáš; Towner, M.C.; Bevan, A.W.R.; Borovička, Jiří; McClafferty, T.; Vaughan, D.

2010-01-01

Roč. 45, Supplement (2010), A16-A16 ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /73./. 26.07.2010-30.07.2010, New York] Institutional research plan: CEZ:AV0Z10030501 Keywords : meteorite falls Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Crater Topography on Titan: Implications for Landscape Evolution

Science.gov (United States)

Neish, Catherine D.; Kirk, R.L.; Lorenz, R. D.; Bray, V. J.; Schenk, P.; Stiles, B. W.; Turtle, E.; Mitchell, K.; Hayes, A.

2013-01-01

We present a comprehensive review of available crater topography measurements for Saturn's moon Titan. In general, the depths of Titan's craters are within the range of depths observed for similarly sized fresh craters on Ganymede, but several hundreds of meters shallower than Ganymede's average depth vs. diameter trend. Depth-to-diameter ratios are between 0.0012 +/- 0.0003 (for the largest crater studied, Menrva, D approximately 425 km) and 0.017 +/- 0.004 (for the smallest crater studied, Ksa, D approximately 39 km). When we evaluate the Anderson-Darling goodness-of-fit parameter, we find that there is less than a 10% probability that Titan's craters have a current depth distribution that is consistent with the depth distribution of fresh craters on Ganymede. There is, however, a much higher probability that the relative depths are uniformly distributed between 0 (fresh) and 1 (completely infilled). This distribution is consistent with an infilling process that is relatively constant with time, such as aeolian deposition. Assuming that Ganymede represents a close 'airless' analogue to Titan, the difference in depths represents the first quantitative measure of the amount of modification that has shaped Titan's surface, the only body in the outer Solar System with extensive surface-atmosphere exchange.

High Resolution Digital Elevation Models of Pristine Explosion Craters

Science.gov (United States)

Farr, T. G.; Krabill, W.; Garvin, J. B.

2004-01-01

In order to effectively capture a realistic terrain applicable to studies of cratering processes and landing hazards on Mars, we have obtained high resolution digital elevation models of several pristine explosion craters at the Nevada Test Site. We used the Airborne Terrain Mapper (ATM), operated by NASA's Wallops Flight Facility to obtain DEMs with 1 m spacing and 10 cm vertical errors of 4 main craters and many other craters and collapse pits. The main craters that were mapped are Sedan, Scooter, Schooner, and Danny Boy. The 370 m diameter Sedan crater, located on Yucca Flat, is the largest and freshest explosion crater on Earth that was formed under conditions similar to hypervelocity impact cratering. As such, it is effectively pristine, having been formed in 1962 as a result of a controlled detonation of a 100 kiloton thermonuclear device, buried at the appropriate equivalent depth of burst required to make a simple crater. Sedan was formed in alluvium of mixed lithology and subsequently studied using a variety of field-based methods. Nearby secondary craters were also formed at the time and were also mapped by ATM. Adjacent to Sedan and also in alluvium is Scooter, about 90 m in diameter and formed by a high-explosive event. Schooner (240 m) and Danny Boy (80 m) craters were also important targets for ATM as they were excavated in hard basalt and therefore have much rougher ejecta. This will allow study of ejecta patterns in hard rock as well as engineering tests of crater and rock avoidance and rover trafficability. In addition to the high resolution DEMs, crater geometric characteristics, RMS roughness maps, and other higher-order derived data products will be generated using these data. These will provide constraints for models of landing hazards on Mars and for rover trafficability. Other planned studies will include ejecta size-frequency distribution at the resolution of the DEM and at finer resolution through air photography and field measurements

Probing the use of spectroscopy to determine the meteoritic analogues of meteors

Science.gov (United States)

Drouard, A.; Vernazza, P.; Loehle, S.; Gattacceca, J.; Vaubaillon, J.; Zanda, B.; Birlan, M.; Bouley, S.; Colas, F.; Eberhart, M.; Hermann, T.; Jorda, L.; Marmo, C.; Meindl, A.; Oefele, R.; Zamkotsian, F.; Zander, F.

2018-05-01

Context. Determining the source regions of meteorites is one of the major goals of current research in planetary science. Whereas asteroid observations are currently unable to pinpoint the source regions of most meteorite classes, observations of meteors with camera networks and the subsequent recovery of the meteorite may help make progress on this question. The main caveat of such an approach, however, is that the recovery rate of meteorite falls is low (100) within a reasonable time frame (10-20 years), the optimal solution may be the spatial extension of existing fireball observation networks. The movie associated to this article is available at http://www.aanda.org

Geologic map of Tooting crater, Amazonis Planitia region of Mars

Science.gov (United States)

Mouginis-Mark, Peter J.

2015-01-01

Tooting crater has a diameter of 27.2 km, and formed on virtually flat lava flows within Amazonis Planitia ~1,300 km west of the summit of Olympus Mons volcano, where there appear to have been no other major topographic features prior to the impact. The crater formed in an area ~185 x 135 km that is at an elevation between −3,870 m and −3,874 m relative to the Mars Orbiter Laser Altimeter (MOLA) Mars datum. This fortuitous situation (for example, a bland, horizontal target) allows the geometry of the crater and the thickness of the ejecta blanket to be accurately determined by subtracting the appropriate elevation of the surrounding landscape (−3,872 m) from the individual MOLA measurements across the crater. Thus, for the first time, it is possible to determine the radial decrease of ejecta thickness as a function of distance away from the rim crest. On the basis of the four discrete ejecta layers surrounding the crater cavity, Tooting crater is classified as a Multiple-Layered Ejecta (MLE) crater. By virtue of the asymmetric distribution of secondary craters and the greater thickness of ejecta to the northeast, Morris and others (2010) proposed that Tooting crater formed by an oblique impact from the southwest. The maximum range of blocks that produced identifiable secondary craters is ~500 km (~36.0 crater radii) from the northeast rim crest. In contrast, secondary craters are only identifiable ~215 km (15.8 radii) to the southeast and 225 km (16.5 radii) to the west.

Pre-Entry Size and Cosmic History of the Annama Meteorite

Czech Academy of Sciences Publication Activity Database

Kohout, Tomáš; Meier, M.M.M.; Maden, C.; Busemann, H.; Welten, K.C.; Laubenstein, M.; Caffee, M. W.; Gritsevich, M.; Grokhovsky, V.

2016-01-01

Roč. 51, SI Supplement 1 (2016), A380-A380 ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /79./. 07.08.2016-12.08.2016, Berlin] Institutional support: RVO:67985831 Keywords : noble gases * cosmogenic radionuclides chondrite * meteorite * Annama Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

U-Pb systematics in iron meteorites: uniformity of primordial lead

International Nuclear Information System (INIS)

Goepel, C.; Manhes, G.; Allegre, C.J.

1985-01-01

Pb isotopic compositions and U-Pb abundances were determined in the metal phase of six iron meteorites: Canyon Diablo IA, Toluca IA, Odessa IA, Youndegin IA, Deport IA and Mundrabilla An. Prior to complete dissolution, samples were subjected to a series of leachings and partial dissolutions. Isotopic compositions and abundances of the etched Pb indicate a contamination by terrestrial Pb which is attributable to previous cutting of the meteorite. Pb isotopic compositions measured in the decontaminated samples are identical within 0.2% and essentially confirm the primordial Pb value defined by Tatsumoto et al. (1973). These data invalidate more radiogenic Pb isotopic compositions published for iron meteorites, which are the result of terrestrial Pb contamination introduced mainly by analytical procedure. Our results support the idea of a solar nebula which was isotopically homogeneous for Pb 4.55 Ga ago. The new upper limit for U-abundance in iron meteorites, 0.001 ppb, is in agreement with its expected thermodynamic solubility in the metal phase. (author)

Studies on Al Kidirate and Kapoeta meteorites

International Nuclear Information System (INIS)

Gismelseed, A.M.; Khangi, F.; Ibrahim, A.; Yousif, A.A.; Worthing, M.A.; Rais, A.; Elzain, M.E.; Brooks, C.K.; Sutherland, H.H.

1994-01-01

Moessbauer spectroscopy (20-300 K), magnetic susceptibility measurements (77-350 K), scanning electron microscopy and X-ray diffraction experiments have been performed on two meteorite samples: one from an old fall (Kapoeta) and another from a very recent fall (Al Kidirate). The two specimens differ in their mineralogy. Chondrules appear to be absent in Kapoeta and it is probably a pyroxene-plagioclase achondrite with ferrohypersthene as the most abundant mineral. On the other hand, the Al Kidirate meteorite is an ordinary chondrite and the specimen consists of olivine, orthopyroxene, troilite and kamacite. The Moessbauer measurements confirm the above characterization, showing a paramagnetic doublet for the Kapoeta sample and at least two paramagnetic doublets and magnetic sextets for the Al Kidirate specimens. The former were assigned to Fe in pyroxene sites, while the latter was assigned to Fe in pyroxene, olivine, Fe-S and Fe-Ni alloys. The difference in the mineralogy of the two meteorites has also been reflected in the temperature-dependent magnetic susceptibility. The magnetization and the hyperfine interaction parameters will be discussed in relation to the mineralogy. (orig.)

Irradiation history of meteoritic inclusions

DEFF Research Database (Denmark)

Wielandt, Daniel Kim Peel

Understanding the formation and earliest evolution of our solar system is a longstanding goal shared by cosmochemistry, astronomy and astrophysics. Meteorites play a key role in this pursuit, providing a ground truth against which all theories must be weighed. Chondritic meteorites are in essence...... extraterrestrial sediments that contain Calcium-Aluminium-rich Inclusions (CAIs) and chondrules that formed as individual objects during the earliest stages of solar system evolution. They later accreted together to form large bodies, after spending up to several million years in individual orbit around the proto...... of presolar and protosolar materials, as well as evidence for the former presence of over 10 extinct shortlived radionuclei of varying stability and provenance that play a key role in deciphering early solar system evolution. Some shortlived radionuclei, such as 60Fe (T½ 2.5 Myr), must have formed...

Methods for determining the preatmospheric dimensions of meteorites

Science.gov (United States)

Ustinova, G. K.; Alekseev, V. A.; Lavrukhina, A. K.

1988-10-01

Methods are proposed for the determination of the preatmospheric size of a meteorite on the basis of data on its cosmogenic radionuclides. Optimal conditions for the application of each of these methods are presented together with the demonstration of their effectiveness. Estimates of relative dimensions determined by these methods are presented for the Harleton, St. Severin, Lost City, Peace River, Pribram, Dhajala, Innisfree, Bruderheim, Ehole, and Gorlovka chondrites and for the Iardymly, Boguslavka, Treysa, and Sikhote-Alin' iron meteorites.

Fungal Peptaibiotics: Assessing Potential Meteoritic Amino Acid Contamination

Science.gov (United States)

Elsila, J. E.; Callahan, M. P.; Glavin, D. P.; Dworkin, J. P.; Bruckner, H.

2010-01-01

The presence of non-protein alpha-dialkyl-amino acids such as alpha-aminoisobutyric acid (alpha-A1B) and isovaline (Iva), which are relatively rare in the terrestrial biosphere, has long been used as an indication of the indigeneity of meteoritic amino acids, however, the discovery of alpha-AIB in peptides producers by a widespread group of filamentous fungi indicates the possibility of a terrestrial biotic source for the alpha-AIB observed in some meteorites. The alpha-AIB-containing peptides produced by these fungi are dubbed peptaibiotics. We measured the molecular distribution and stable carbon and nitrogen isotopic ratios for amino acids found in the total hydrolysates of four biologically synthesized peptaibiotics. We compared these aneasurenetts with those from the CM2 carbonaceous chondrite Murchison and from three Antarctic CR2 carbonaceous chondrites in order to understand the peptaibiotics as a potential source of meteoritic contamination.

Optimizing laser crater enhanced Raman spectroscopy.

Science.gov (United States)

Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

2018-03-20

Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Detection and rapid recovery of the Sutter's Mill meteorite fall as a model for future recoveries worldwide

Science.gov (United States)

Fries, Marc; Le Corre, Lucille; Hankey, Mike; Fries, Jeff; Matson, Robert; Schaefer, Jake; Reddy, Vishnu

2014-11-01

The Sutter's Mill C-type meteorite fall occurred on 22 April 2012 in and around the town of Coloma, California. The exact location of the meteorite fall was determined within hours of the event using a combination of eyewitness reports, weather radar imagery, and seismometry data. Recovery of the first meteorites occurred within 2 days and continued for months afterward. The recovery effort included local citizens, scientists, and meteorite hunters, and featured coordination efforts by local scientific institutions. Scientific analysis of the collected meteorites revealed characteristics that were available for study only because the rapid collection of samples had minimized terrestrial contamination/alteration. This combination of factors—rapid and accurate location of the event, participation in the meteorite search by the public, and coordinated scientific investigation of recovered samples—is a model that was widely beneficial and should be emulated in future meteorite falls. The tools necessary to recreate the Sutter's Mill recovery are available, but are currently underutilized in much of the world. Weather radar networks, scientific institutions with interest in meteoritics, and the interested public are available globally. Therefore, it is possible to repeat the Sutter's Mill recovery model for future meteorite falls around the world, each for relatively little cost with a dedicated researcher. Doing so will significantly increase the number of fresh meteorite falls available for study, provide meteorite material that can serve as the nuclei of new meteorite collections, and will improve the public visibility of meteoritics research.

The Virtual Museum for Meteorites: an Online Tool for Researchers Educators and Students

Science.gov (United States)

Madiedo, J. M.

2013-09-01

The Virtual Museum for Meteorites (Figure 1) was created as a tool for students, educators and researchers [1, 2]. One of the aims of this online resource is to promote the interest in meteorites. Thus, the role of meteorites in education and outreach is fundamental, as these are very valuable tools to promote the public's interest in Astronomy and Planetary Sciences. Meteorite exhibitions reveal the fascination of students, educators and even researchers for these extraterrestrial rocks and how these can explain many key questions origin and evolution of our Solar System. However, despite the efforts related to the origin and evolution of our Solar System. However, despite the efforts of private collectors, museums and other institutions to organize meteorite exhibitions, the reach of these is usually limited. The Virtual Museum for Meteorites takes advantage of HTML and related technologies to overcome local boundaries and offer its contents for a global audience. A description of the recent developments performed in the framework of this virtual museum is given in this work.

Cathodoluminescence and Raman Spectromicroscopy of Forsterite in Tagish Lake Meteorite: Implications for Astromineralogy

Directory of Open Access Journals (Sweden)

Arnold Gucsik

2016-01-01

Full Text Available The Tagish Lake meteorite is CI/CM2 chondrite, which fell by a fireball event in January 2000. This study emphasizes the cathodoluminescence (CL and Raman spectroscopical properties of the Tagish Lake meteorite in order to classify the meteoritic forsterite and its relation to the crystallization processes in a parent body. The CL-zoning of Tagish Lake meteorite records the thermal history of chondrules and terrestrial weathering. Only the unweathered olivine is forsterite, which is CL-active. The variation of luminescence in chondrules of Tagish Lake meteorite implies chemical inhomogeneity due to low-grade thermal metamorphism. The blue emission center in forsterite due to crystal lattice defect is proposed as being caused by rapid cooling during the primary crystallization and relatively low-temperature thermal metamorphism on the parent body of Tagish Lake meteorite. This is in a good agreement with the micro-Raman spectroscopical data. A combination of cathodoluminescence and micro-Raman spectroscopies shows some potentials in study of the asteroidal processes of parent bodies in solar system.

Analysis of a potential meteorite-dropping event over the south of Spain in 2007

Science.gov (United States)

Madiedo, J. M.; Trigo-Rodríguez, J. M.

2008-09-01

Introduction Four potential meteorite-dropping events happened over Spain during 2007. All them are being carefully studied in the framework of the SPanish Meteor Network (SPMN). Due to the large range of visibility of these events, they usually appear far away from the recording stations, or in broad daylight. The later was the case of the most remarkable of these events: the diurnal bolide witnessed by thousands of people in the afternoon of May 10, at 17h57m01±5s UTC. That magnificent daylight event produced the Puerto Lápice meteorite, an eucrite with a total known weight of about 500 grams [1, 2]. Other wonderful event happened during the afternoon of March 2, 2007 at 18h51m06±1s UTC: a magnificent bolide (Fig. 1) was seen over the Pyrenees by several eyewitnesses located in Catalonia and Aragon, but also from the South of France. Unfortunately it was not recorded by SPMN stations and a very limited number of visual reports were received. Figure 1. The appearance of the March 2, 2007 bolide as drawn made by the second author and fortunate eyewitness from Sant Celoni (Barcelona). Another potential meteorite-dropping diurnal bolide was witnessed from several locations over the south of Spain on the afternoon of June 29. A sonic boom was reported by witnesses located near from the estimated impact area, in the province of Huelva (Andalusia). In some cases these also reported that the bolide generated electrophonic sounds and that the sonic boom was accompanied by vibration of objects inside their houses. However, despite several expeditions to the impact area have been made, the meteorite produced by this bolide has not been found yet. This is mainly due to the high uncertainty in the calculation of the impact point, as the region is quite unpopulated and just about a dozen of eyewitnesses could be interviewed. On the other hand, the characteristics of the vegetation that grows in the area also poses important difficulties to the search tasks. Besides, as in

On presolar meteoritic sulphides

International Nuclear Information System (INIS)

Clayton, D.D.; Ramadurai, S.

1977-01-01

It is stated that discoveries of isotopic anomalies in meteorites caused some workers to postulate nucleosynthetic inhomogeneities that were somehow carried into the early solar system. A picture was developed treating most anomalies as extinct radioactivities trapped in mineral condensations in the expanding sites of explosive nucleosynthesis, such as supernovae or novae. As evidence for this grows it becomes clear that not only isotopic but also mineralogical evidence of presolar grains is wanted, and also knowledge of what supernovae condensates are likely to survive. It is suggested here that a search should be made among sulphides in meteorites, searching especially for sulphides of Ti. The reasoning is that many sulphides, especially Ti sulphides, will not be expected in solar condensation sequences, but are expected to dominate certain key zones of supernovae expansion. Sulphur seems to have resulted primarily from the nuclear explosions of O and Si, and arguments leading to that conclusion are analysed. It is thought that the discussion could lead to important discoveries for nucleosynthesis and the origin of the solar system. (U.K.)

100 New Impact Crater Sites Found on Mars

Science.gov (United States)

Kennedy, M. R.; Malin, M. C.

2009-12-01

Recent observations constrain the formation of 100 new impact sites on Mars over the past decade; 19 of these were found using the Mars Global Surveyor Mars Orbiter Camera (MOC), and the other 81 have been identified since 2006 using the Mars Reconnaissance Orbiter Context Camera (CTX). Every 6 meter/pixel CTX image is examined upon receipt and, where they overlap images of 0.3-240 m/pixel scale acquired by the same or other Mars-orbiting spacecraft, we look for features that may have changed. New impact sites are initially identified by the presence of a new dark spot or cluster of dark spots in a CTX image. Such spots may be new impact craters, or result from the effect of impact blasts on the dusty surface. In some (generally rare) cases, the crater is sufficiently large to be resolved in the CTX image. In most cases, however, the crater(s) cannot be seen. These are tentatively designated as “candidate” new impact sites, and the CTX team then creates an opportunity for the MRO spacecraft to point its cameras off-nadir and requests that the High Resolution Imaging Science Experiment (HiRISE) team obtain an image of ~0.3 m/pixel to confirm whether a crater or crater cluster is present. It is clear even from cursory examination that the CTX observations are areographically biased to dusty, higher albedo areas on Mars. All but 3 of the 100 new impact sites occur on surfaces with Lambert albedo values in excess of 23.5%. Our initial study of MOC images greatly benefited from the initial global observations made in one month in 1999, creating a baseline date from which we could start counting new craters. The global coverage by MRO Mars Color Imager is more than a factor of 4 poorer in resolution than the MOC Wide Angle camera and does not offer the opportunity for global analysis. Instead, we must rely on partial global coverage and global coverage that has taken years to accumulate; thus we can only treat impact rates statistically. We subdivide the total data

A Propensity for n-omega-Amino Acids in Thermally-Altered Antarctic Meteorites

Science.gov (United States)

Burton, Aaron S.; Elsila, Jamie E.; Callahan, Michael P.; Martin, Mildred G.; Glavin, Daniel P.; Johnson, Natasha M.; Dworkin, Jason P.

2012-01-01

Carbonaceous meteorites are known to contain a wealth of indigenous organic molecules, including amino acids, which suggests that these meteorites could have been an important source of prebiotic organic material during the origins of life on Earth and possibly elsewhere. We report the detection of extraterrestrial amino acids in thermally-altered type 3 CV and CO carbonaceous chondrites and ureilites recovered from Antarctica. The amino acid concentrations of the thirteen Antarctic meteorites were generally less abundant than in more amino acid-rich CI, CM, and CR carbonaceous chondrites that experienced much lower temperature aqueous alteration on their parent bodies. In contrast to low-temperature aqueously-altered meteorites that show complete structural diversity in amino acids formed predominantly by Strecker-cyanohydrin synthesis, the thermally-altered meteorites studied here are dominated by small, straight-chain, amine terminal (n-omega-amino) amino acids that are not consistent with Strecker formation. The carbon isotopic ratios of two extraterrestrial n-omega-amino acids measured in one of the CV chondrites are consistent with C-13-depletions observed previously in hydrocarbons produced by Fischer-Tropsch type reactions. The predominance of n-omega-amino acid isomers in thermally-altered meteorites hints at cosmochemical mechanisms for the preferential formation and preservation of a small subset of the possible amino acids.

Parent Body Influences on Amino Acids in the Tagish Lake Meteorite

Science.gov (United States)

Glavin, D. P.; Callahan, M. P.; Dworkin, J. P.; Elsila, J. E.; Herd, C. D. K.

2010-01-01

The Tagish Lake meteorite is a primitive C2 carbonaceous chondrite with a mineralogy, oxygen isotope, and bulk chemical. However, in contrast to many CI and CM carbonaceous chondrites, the Tagish Lake meteorite was reported to have only trace levels of indigenous amino acids, with evidence for terrestrial L-amino acid contamination from the Tagish Lake meltwater. The lack of indigenous amino acids in Tagish Lake suggested that they were either destroyed during parent body alteration processes and/or the Tagish Lake meteorite originated on a chemically distinct parent body from CI and CM meteorites where formation of amino acids was less favorable. We recently measured the amino acid composition of three different lithologies (11h, 5b, and 11i) of pristine Tagish Lake meteorite fragments that represent a range of progressive aqueous alteration in order 11h amino acids found in hot-water extracts of the Tagish Lake fragments were determined by ultra performance liquid chromatography fluorescence detection and time of flight mass spectrometry coupled with OPA/NAC derivatization. Stable carbon isotope analyses of the most abundant amino acids in 11h were measured with gas chromatography coupled with quadrupole mass spectrometry and isotope ratio mass spectrometry.

Geological Mapping of Impact Melt Deposits at Lunar Complex Craters: New Insights into Morphological Diversity, Distribution and the Cratering Process

Science.gov (United States)

Dhingra, D.; Head, J. W., III; Pieters, C. M.

2014-12-01

We have completed high resolution geological mapping of impact melt deposits at the young lunar complex craters (wall and rim impact melt units and their relation to floor units have also been mapped. Among the distinctive features of these impact melt deposits are: 1) Impact Melt Wave Fronts: These are extensive (sometimes several kilometers in length) and we have documented their occurrence and distribution in different parts of the crater floor at Jackson and Tycho. These features emphasize melt mobility and style of emplacement during the modification stage of the craters. 2) Variations in Floor Elevations: Spatially extensive and coherent sections of crater floors have different elevations at all the three craters. The observed elevation differences could be caused by subsidence due to cooling of melt and/or structural failure, together with a contribution from regional slope. 3) Melt-Covered Megablocks: We also observe large blocks/rock-fragments (megablocks) covered in impact melt, which could be sections of collapsed wall or in some cases, subdued sections of central peaks. 4) Melt-Covered Central Peaks: Impact melt has also been mapped on the central peaks but varies in spatial extent among the craters. The presence of melt on peaks must be taken into account when interpreting peak mineralogy as exposures of deeper crust. 5) Boulder Distribution: Interesting trends are observed in the distribution of boulder units of various sizes; some impact melt units have spatially extensive boulders, while boulder distribution is very scarce in other units on the floor. We interpret these distributions to be influenced by a) the differential collapse of the crater walls during the modification stage, and b) the amount of relative melt volume retained in different parts of the crater floor. These observations provide important documentation of the morphological diversity and better understanding of the emplacement and final distribution of impact melt deposits.

Surface age of venus: use of the terrestrial cratering record

International Nuclear Information System (INIS)

Schaber, G.G.; Shoemaker, E.M.; Kozak, R.C.

1987-01-01

The average crater age of Venus' northern hemisphere may be less than 250 m.y. assuming equivalence between the recent terrestrial cratering rate and that on Venus for craters ≥ 20 km in diameter. For craters larger than this threshold size, below which crater production is significantly affected by the Venusian atmosphere, there are fairly strong observational grounds for concluding that such an equivalence in cratering rates on Venus and Earth may exist. However, given the uncertainties in the role of both active and inactive comet nuclei in the cratering history of Earth, we conclude that the age of the observed surface in the northern hemisphere of Venus could be as great as the 450-m.y. mean age of the Earth's crust. The observed surface of Venus might be even older, but no evidence from the crater observations supports an age as great as 1 b.y. If the age of the observed Venusian surface were 1 b.y., it probably should bear the impact scars of a half dozen or more large comet nuclei that penetrated the atmosphere and formed craters well over 100 km in diameter. Venera 15/16 mapped only about 25% of Venus; the remaining 75% may tell us a completely different story

Origins of mass-dependent and mass-independent Ca isotope variations in meteoritic components and meteorites

Science.gov (United States)

Bermingham, K. R.; Gussone, N.; Mezger, K.; Krause, J.

2018-04-01

The Ca isotope composition of meteorites and their components may vary due to mass-dependent and/or -independent isotope effects. In order to evaluate the origin of these effects, five amoeboid olivine aggregates (AOAs), three calcium aluminum inclusions (CAIs), five chondrules (C), a dark inclusion from Allende (CV3), two dark fragments from North West Africa 753 (NWA 753; R3.9), and a whole rock sample of Orgueil (CI1) were analyzed. This is the first coupled mass-dependent and -independent Ca isotope dataset to include AOAs, a dark inclusion, and dark fragments. Where sample masses permit, Ca isotope data are reported with corresponding petrographic analyses and rare earth element (REE) relative abundance patterns. The CAIs and AOAs are enriched in light Ca isotopes (δ44/40Ca -5.32 to +0.72, where δ44/40Ca is reported relative to SRM 915a). Samples CAI 5 and AOA 1 have anomalous Group II REE patterns. These REE and δ44/40Ca data suggest that the CAI 5 and AOA 1 compositions were set via kinetic isotope fractionation during condensation and evaporation. The remaining samples show mass-dependent Ca isotope variations which cluster between δ44/40Ca +0.53 and +1.59, some of which are coupled with unfractionated REE abundance patterns. These meteoritic components likely formed through the coaccretion of the evaporative residue and condensate following Group II CAI formation or their chemical and isotopic signatures were decoupled (e.g., via nebular or parent-body alteration). The whole rock sample of Orgueil has a δ44/40Ca +0.67 ± 0.18 which is in agreement with most published data. Parent-body alteration, terrestrial alteration, and variable sampling of Ca-rich meteoritic components can have an effect on δ44/40Ca compositions in whole rock meteorites. Samples AOA 1, CAI 5, C 2, and C 4 display mass-independent 48/44Ca anomalies (ε48/44Ca +6 to +12) which are resolved from the standard composition. Other samples measured for these effects (AOA 5, CAI 1, CAI 2

Impact spacecraft imagery and comparative morphology of craters

International Nuclear Information System (INIS)

Moutsoulas, M.; Piteri, S.

1979-01-01

The use of hard-landing 'simple' missions for wide-scale planetary exploration is considered. As an example of their imagery potentialities, Ranger VII data are used for the study of the morphological characteristics of 16 Mare Cognitum craters. The morphological patterns of lunar craters, expressed in terms of the Depth/Diameter ratios appear to be in most cases independent of the crater location or size. (Auth.)

Geomorphology of crater and basin deposits - Emplacement of the Fra Mauro formation

Science.gov (United States)

Morrison, R. H.; Oberbeck, V. R.

1975-01-01

Characteristics of continuous deposits near lunar craters larger than about 1 km wide are considered, and it is concluded that (1) concentric dunes, radial ridges, and braided lineations result from deposition of the collision products of ejecta from adjacent pairs of similarly oriented secondary-crater chains and are, therefore, concentrations of secondary-crater ejecta; (2) intracrater ridges are produced within preexisting craters surrounding a fresh primary crater by ricocheting and focusing of secondary-crater ejecta from the preexisting craters' walls; and (3) secondary cratering has produced many of the structures of the continuous deposits of relatively small lunar craters and is the dominant process for emplacement of most of the radial facies of the continuous deposits of large lunar craters and basins. The percentages of Imbrium ejecta in deposits and the nature of Imbrium sculpturing are investigated.

An assessment of the meteoritic contribution to the Martian soil

International Nuclear Information System (INIS)

Flynn, G.J.; McKay, D.S.

1990-01-01

The addition of meteoritic material to the Mars soils should perturb their chemical compositions, as has been detected for soils on the Moon and sediments on Earth. Using the measured mass influx at Earth and estimates of the Mars/Earth flux ratio, the authors estimate the continuous, planet-wide meteoritic mass influx on Mars to be between 2,700 and 59,000 t/yr. If distributed uniformly into a soil with a mean planetary production rate of 1 m/b.y., consistent with radar estimates of the soil depth overlaying a bouldered terrain in the Tharsis region, their estimated mass influx would produce a meteoritic concentration in the Mars soil ranging from 2 to 29% by mass. Analysis of the Viking X ray fluorescence data indicates that the Mars soil composition is inconsistent with typical basaltic rock fragments but can be fit by a mixture of 60% basaltic rock fragments and 40% meteoritic material. The meteoritic influx they calculate is sufficient to provide most or all of the material required by the Clark and Baird model. Particles in the mass range from 10 -7 to 10 -3 g, about 60-1,200 μm in diameter, contribute 80% of the total mass flux of meteoritic material in the 10 -13 to 10 6 g mass range at Earth. On Earth atmospheric entry all but the smallest particles (generally ≤ 50 μm in diameter) in the 10 -7 to 10 -3 g mass range are heated sufficiently to melt or vaporize. Mars, because of its lower escape velocity and larger atmospheric scale height, is a much more favorable site for unmelted survival of micrometeorites on atmospheric deceleration. They calculate that a significant fraction of particles throughout the 60-1,200 μm diameter range will survive Mars atmospheric entry unmelted

A concept of row crater enhancement

International Nuclear Information System (INIS)

Redpath, B.B.

1970-01-01

Linear craters formed by the simultaneous detonation of a row of buried explosives will probably have a wider application than single charges in the explosive excavation of engineering structures. Most cratering experience to date has been with single charges, and an analytical procedure for the design of a row of charges to excavate a crater with a specified configuration has been lacking. There are no digital computer codes having direct application to a row of charges as there are for single charges. This paper derives a simple relationship which can be used to design row charges with some assurance of achieving the desired result and with considerable flexibility in the choice of explosive yield of the individual charges

Inaugeral lecture - Meteorite impacts on Earth and on the Earth ...

African Journals Online (AJOL)

There is some controversial evidence for the theory that the first life on Earth itself may have been transported here on meteorites from Mars. The possibility of a major meteorite impact on Earth in the near future emphasizes the dramatic nature of these recent discoveries, which are having deep impacts in the Earth sciences ...

The Prevailing Catalytic Role of Meteorites in Formamide Prebiotic Processes

Directory of Open Access Journals (Sweden)

Raffaele Saladino

2018-02-01

Full Text Available Meteorites are consensually considered to be involved in the origin of life on this Planet for several functions and at different levels: (i as providers of impact energy during their passage through the atmosphere; (ii as agents of geodynamics, intended both as starters of the Earth’s tectonics and as activators of local hydrothermal systems upon their fall; (iii as sources of organic materials, at varying levels of limited complexity; and (iv as catalysts. The consensus about the relevance of these functions differs. We focus on the catalytic activities of the various types of meteorites in reactions relevant for prebiotic chemistry. Formamide was selected as the chemical precursor and various sources of energy were analyzed. The results show that all the meteorites and all the different energy sources tested actively afford complex mixtures of biologically-relevant compounds, indicating the robustness of the formamide-based prebiotic chemistry involved. Although in some cases the yields of products are quite small, the diversity of the detected compounds of biochemical significance underlines the prebiotic importance of meteorite-catalyzed condensation of formamide.

The Prevailing Catalytic Role of Meteorites in Formamide Prebiotic Processes.

Science.gov (United States)

Saladino, Raffaele; Botta, Lorenzo; Di Mauro, Ernesto

2018-02-22

Meteorites are consensually considered to be involved in the origin of life on this Planet for several functions and at different levels: (i) as providers of impact energy during their passage through the atmosphere; (ii) as agents of geodynamics, intended both as starters of the Earth's tectonics and as activators of local hydrothermal systems upon their fall; (iii) as sources of organic materials, at varying levels of limited complexity; and (iv) as catalysts. The consensus about the relevance of these functions differs. We focus on the catalytic activities of the various types of meteorites in reactions relevant for prebiotic chemistry. Formamide was selected as the chemical precursor and various sources of energy were analyzed. The results show that all the meteorites and all the different energy sources tested actively afford complex mixtures of biologically-relevant compounds, indicating the robustness of the formamide-based prebiotic chemistry involved. Although in some cases the yields of products are quite small, the diversity of the detected compounds of biochemical significance underlines the prebiotic importance of meteorite-catalyzed condensation of formamide.

Cutting Craters

Science.gov (United States)

2003-01-01

[figure removed for brevity, see original site] Released 12 November 2003The rims of two old and degraded impact craters are intersected by a graben in this THEMIS image taken near Mangala Fossa. Yardangs and low-albedo wind streaks are observed at the top of the image as well as interesting small grooves on the crater floor. The origin of these enigmatic grooves may be the result of mud or lava and volatile interactions. Variable surface textures observed in the bottom crater floor are the result of different aged lava flows.Image information: VIS instrument. Latitude -15.2, Longitude 219.2 East (140.8 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Microfossils, biomolecules and biominerals in carbonaceous meteorites: implications to the origin of life

Science.gov (United States)

Hoover, Richard B.

2012-11-01

Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) investigations have shown that a wide variety of carbonaceous meteorites contain the remains of large filaments embedded within freshly fractured interior surfaces of the meteorite rock matrix. The filaments occur singly or in dense assemblages and mats and are often encased within carbon-rich, electron transparent sheaths. Electron Dispersive X-ray Spectroscopy (EDS) spot analysis and 2D X-Ray maps indicate the filaments rarely have detectable nitrogen levels and exhibit elemental compositions consistent with that interpretation that of the meteorite rock matrix. Many of the meteorite filaments are exceptionally well-preserved and show evidence of cells, cell-wall constrictions and specialized cells and processes for reproduction, nitrogen fixation, attachment and motility. Morphological and morphometric analyses permit many of the filaments to be associated with morphotypes of known genera and species of known filamentous trichomic prokaryotes (cyanobacteria and sulfur bacteria). The presence in carbonaceous meteorites of diagenetic breakdown products of chlorophyll (pristane and phytane) along with indigenous and extraterrestrial chiral protein amino acids, nucleobases and other life-critical biomolecules provides strong support to the hypothesis that these filaments represent the remains of cyanobacteria and other microorganisms that grew on the meteorite parent body. The absence of other life-critical biomolecules in the meteorites and the lack of detectable levels of nitrogen indicate the filaments died long ago and can not possibly represent modern microbial contaminants that entered the stones after they arrived on Earth. This paper presents new evidence for microfossils, biomolecules and biominerals in carbonaceous meteorites and considers the implications to some of the major hypotheses for the Origin of Life.

The fall of a meteorite at Aegos Potami in 467/6 BC

Science.gov (United States)

Theodossiou, E. Th; Niarchos, P. G.; Manimanis, V. N.; Orchiston, W.

2002-12-01

Cosmic catastrophes have been associated from time to time with the fall of celestial objects to Earth. From the writings of ancient Greek authors we know that during the second year of the 78th Olympiad, that is the year corresponding to 467/6 BC, a very large meteorite fell at Aegos Potami, in the Gallipoli Peninsula (in Eastern Thrace). This event was predicted by Anaxagoras, and the meteorite was worshipped by the Cherronesites until at least the first Century AD. The fall of the Aegos Potami Meteorite was not associated with any cosmic catastrophe, but it was believed to have foretold the terminal defeat of the Athenians by the Spartans in 405 BC near Aegos Potami, which brought to an end the Peloponnesian War in favour of Sparta. In addition, according to the Latin author Pliny the Elder, during the first century AD the inhabitants of Avydus in Asia Minor worshipped another meteorite that was displayed in the city's sports centre, The fall of this meteorite is also said to have been predicted by Anaxagoras.

Crater populations in the early history of Mercury

International Nuclear Information System (INIS)

Guest, J.E.; Gault, D.E.

1976-01-01

Crater populations on two major geologic units of Mercury have been classified into three morphologic types which characterize their state of degradation. The results indicate that one or more processes either prior to or contemporary with the formation of the 1300 km diameter Caloris Planitia reduced the population of fresh craters smaller than 70--80 km diameter and totally erased the population of fresh craters smaller than 20--30 km

Variability in Abundances of Meteorites in the Ordovician

Science.gov (United States)

Heck, P. R.; Schmitz, B.; Kita, N.

2017-12-01

The knowledge of the flux of extraterrestrial material throughout Earth's history is of great interest to reconstruct the collisional evolution of the asteroid belt. Here, we present a review of our investigations of the nature of the meteorite flux to Earth in the Ordovician, one of the best-studied time periods for extraterrestrial matter in the geological record [1]. We base our studies on compositions of extraterrestrial chromite and chrome-spinel extracted by acid dissolution from condensed marine limestone from Sweden and Russia [1-3]. By analyzing major and minor elements with EDS and WDS, and three oxygen isotopes with SIMS we classify the recovered meteoritic materials. Today, the L and H chondrites dominate the meteorite and coarse micrometeorite flux. Together with the rarer LL chondrites they have a type abundance of 80%. In the Ordovician it was very different: starting from 466 Ma ago 99% of the flux was comprised of L chondrites [2]. This was a result of the collisional breakup of the parent asteroid. This event occurred close to an orbital resonance in the asteroid belt and showered Earth with >100x more L chondritic material than today during more than 1 Ma. Although the flux is much lower at present, L chondrites are still the dominant type of meteorites that fall today. Before the asteroid breakup event 467 Ma ago the three groups of ordinary chondrites had about similar abundances. Surprisingly, they were possibly surpassed in abundance by achondrites, materials from partially and fully differentiated asteroids [3]. These achondrites include HED meteorites, which are presumably fragments released during the formation of the Rheasilvia impact structure 1 Ga ago on asteroid 4 Vesta. The enhanced abundance of LL chondrites is possibly a result of the Flora asteroid family forming event at 1 Ga ago. The higher abundance of primitive achondrites was likely due to smaller asteroid family forming events that have not been identified yet but that did

Cratering on Small Bodies: Lessons from Eros

Science.gov (United States)

Chapman, C. R.

2003-01-01

Cratering and regolith processes on small bodies happen continuously as interplanetary debris rains down on asteroids, comets, and planetary satellites. Butthey are very poorly observed and not well understood. On the one hand, we have laboratory experimentation at small scales and we have examination of large impact craters (e.g. Meteor Crater on Earth and imaging of abundant craters on terrestrial planets and outer planet moons). Understanding cratering on bodies of intermediate scales, tens of meters to hundreds of km in size, involves either extrapolation from our understanding of cratering phenomena at very different scales or reliance on very preliminary, incomplete examination of the observational data we now have for a few small bodies. I review the latter information here. It has been generally understood that the role of gravity is greatly diminished for smaller bodies, so a lot of cratering phenomena studied for larger bodies is less applicable. But it would be a mistake to imagine that laboratory experiments on gravitationless rocks (usually at 1 g) are directly applicable, except perhaps to those monolithic Near Earth Asteroids (NEAs) some tens of meters in size that spin very rapidly and can be assumed to be "large bare rocks" with "negative gravity". Whereas it had once been assumed that asteroids smaller than some tens of km diameter would retain little regolith, it is increasingly apparent that regolith and megoregolith processes extend down to bodies only hundreds of meters in size, perhaps smaller. Yet these processes are very different from those that pertain to the Moon, which is our chief prototype of regolith processes. The NEAR Shoemaker spacecraft's studies of Eros provide the best evidence to date about small-body cratering processes, as well as a warning that our theoretical understanding requires anchoring by direct observations. Eros: "Ponds", Paucity of Small Craters, and Other Mysteries. Although Eros is currently largely detached

The Meteorite Fall in Carancas, Lake Titicaca Region, Southern Peru: First Results

Science.gov (United States)

Núñez Del Prado, H.; Macharé, J.; Macedo, L.; Chirif, H.; Pari, W.; Ramirez-Cardona, M.; Aranda, A.; Greenwood, R. C.; Franchi, I. A.; Canepa, C.; Bernhardt, H.-J.; Plascencia, L.

2008-03-01

The meteorite fall that occurred on September 15, 2007, in the Carancas community is a rare case where it is possible to study both impact phenomenology and meteorite characteristics, including accurate time framework.

Impact cratering on porous targets in the strength regime

Science.gov (United States)

Nakamura, Akiko M.

2017-12-01

Cratering on small bodies is crucial for the collision cascade and also contributes to the ejection of dust particles into interplanetary space. A crater cavity forms against the mechanical strength of the surface, gravitational acceleration, or both. The formation of moderately sized craters that are sufficiently larger than the thickness of the regolith on small bodies, in which mechanical strength plays the dominant role rather than gravitational acceleration, is in the strength regime. The formation of microcraters on blocks on the surface is also within the strength regime. On the other hand, the formation of a crater of a size comparable to the thickness of the regolith is affected by both gravitational acceleration and cohesion between regolith particles. In this short review, we compile data from the literature pertaining to impact cratering experiments on porous targets, and summarize the ratio of spall diameter to pit diameter, the depth, diameter, and volume of the crater cavity, and the ratio of depth to diameter. Among targets with various porosities studied in the laboratory to date, based on conventional scaling laws (Holsapple and Schmidt, J. Geophys. Res., 87, 1849-1870, 1982) the cratering efficiency obtained for porous sedimentary rocks (Suzuki et al., J. Geophys. Res. 117, E08012, 2012) is intermediate. A comparison with microcraters formed on a glass target with impact velocities up to 14 km s-1 indicates a different dependence of cratering efficiency and depth-to-diameter ratio on impact velocity.

A petrogenetic model of the relationships among achondritic meteorites

Science.gov (United States)

Stolper, E.; Hays, J. F.; Mcsween, H. Y., Jr.

1979-01-01

Petrological evidence is used to support the hypothesis that although the magma source regions and parent bodies of basaltic achondrite, shergottite, nakhlite, and chassignite meteorites are clearly distinct, they may be simply related. It is proposed that the peridotites which on partial melting generated the parent magmas of the shergottite meteorites differed from those which gave rise to eucritic magmas by being enriched in a component rich in alkalis and other volatiles. Similarly, the source regions of the parent magmas of the nakhlite and chassignite meteorites differed from those on the shergottite parent body by being still richer in this volatile-rich component. These regions could have been related by processes such as mixture of variable amounts of volatile-rich and volatile-poor components in planetary or nebular settings, or alternatively by variable varying degrees of volatile loss from volatile-rich materials.

Planetary sciences and exploration: An Indian perspective

Indian Academy of Sciences (India)

Studies of impact craters records in the Indian shield have also been pursued and led to ... and emission of X-rays from planets as well as analytical modelling of martian ionosphere and ... Meteorite; moon; solar activity; solar system; martian atmosphere; planetary .... face layers of any meteorite reaching the earth, one.

Topography of the Martian Impact Crater Tooting

Science.gov (United States)

Mouginis-Mark, P. J.; Garbeil, H.; Boyce, J. M.

2009-01-01

Tooting crater is approx.29 km in diameter, is located at 23.4degN, 207.5degE, and is classified as a multi-layered ejecta crater [1]. Our mapping last year identified several challenges that can now be addressed with HiRISE and CTX images, but specifically the third dimension of units. To address the distribution of ponded sediments, lobate flows, and volatile-bearing units within the crater cavity, we have focused this year on creating digital elevation models (DEMs) for the crater and ejecta blanket from stereo CTX and HiRISE images. These DEMs have a spatial resolution of approx.50 m for CTX data, and 2 m for HiRISE data. Each DEM is referenced to all of the available individual MOLA data points within an image, which number approx.5,000 and 800 respectively for the two data types

A global catalogue of Ceres impact craters ≥ 1 km and preliminary analysis

Science.gov (United States)

Gou, Sheng; Yue, Zongyu; Di, Kaichang; Liu, Zhaoqin

2018-03-01

The orbital data products of Ceres, including global LAMO image mosaic and global HAMO DTM with a resolution of 35 m/pixel and 135 m/pixel respectively, are utilized in this research to create a global catalogue of impact craters with diameter ≥ 1 km, and their morphometric parameters are calculated. Statistics shows: (1) There are 29,219 craters in the catalogue, and the craters have a various morphologies, e.g., polygonal crater, floor fractured crater, complex crater with central peak, etc.; (2) The identifiable smallest crater size is extended to 1 km and the crater numbers have been updated when compared with the crater catalogue (D ≥ 20 km) released by the Dawn Science Team; (3) The d/D ratios for fresh simple craters, obviously degraded simple crater and polygonal simple crater are 0.11 ± 0.04, 0.05 ± 0.04 and 0.14 ± 0.02 respectively. (4) The d/D ratios for non-polygonal complex crater and polygonal complex crater are 0.08 ± 0.04 and 0.09 ± 0.03. The global crater catalogue created in this work can be further applied to many other scientific researches, such as comparing d/D with other bodies, inferring subsurface properties, determining surface age, and estimating average erosion rate.

Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

Science.gov (United States)

Welten, K. C.; Alderliesten, C.; Lindner, L.

1992-07-01

INTRODUCTION: We have embarked upon a ^26Al gamma-ray survey of meteorites selected from about 2000 samples recently recovered from the Lewis Cliff Ice Fields (84 degrees 18'S/161 degrees 20'E). Due to its 705-ka half-life ^26Al can be used for estimating terrestrial ages and thus contribute to further characterization of Antarctic meteorites in addition to their classification and thermoluminescence (TL) properties. The ^26Al survey is also useful for identifying meteorites with unusual exposure histories, which merit additional measurements of cosmogenic radionuclides (by AMS) and noble gases. In addition, it provides clues on possible pairings. METHOD: Low-level gamma-ray spectroscopy is well suited for ^26Al survey work, since bulk meteorite samples can be measured routinely and nondestructively without any previous sample preparation. The required size of the samples (30-500 g) makes the method relatively independent of depth effects and compositional inhomogeneities. The use of a high-resolution GeLi detector also allows the determination of the natural ^40K activity and thus the K content of the samples, which can be used as an additional pairing criterion for ordinary chondrites. Also ^137Cs, a fall-out surface contamination [1], is simultaneously measured; low values may be characteristic for meteorites recently fallen or released from the ablating ice. For the detector an efficiency calibration curve has been made that adequately accounts for differences in size and shape of the meteorite samples. RESULTS and DISCUSSION: TERRESTRIAL AGES: So far, we have measured over 30 Lewis Cliff equilibrated H and L chondrites, collected from widely differing locations. Normalized to L-chondrite composition, the ^26Al contents range from 27 to 110 dpm/kg with peaks around 43 and 53 dpm/kg. This bimodal ^26Al distribution is reminiscent of that observed for Allan Hills ordinary chondrites [2]. Tentative terrestrial ages, calculated on the basis of ^26Al saturation

Meteorite Falls Observed in U.S. Weather Radar Data in 2015 and 2016 (To Date)

Science.gov (United States)

Fries, Marc; Fries, Jeffrey; Hankey, Mike; Matson, Robert

2016-01-01

To date, over twenty meteorite falls have been located in the weather radar imagery of the National Oceanic and Atmospheric Administration (NOAA)'s NEXRAD radar network. We present here the most prominent events recorded since the last Meteoritical Society meeting, covering most of 2015 and early 2016. Meteorite Falls: The following events produced evidence of falling meteorites in radar imagery and resulted in meteorites recovered at the fall site. Creston, CA (24 Oct 2015 0531 UTC): This event generated 218 eyewitness reports submitted to the American Meteor Society (AMS) and is recorded as event #2635 for 2015 on the AMS website. Witnesses reported a bright fireball with fragmentation terminating near the city of Creston, CA, north of Los Angeles. Sonic booms and electrophonic noise were reported in the vicinity of the event. Weather radar imagery records signatures consistent with falling meteorites in data from the KMUX, KVTX, KHNX and KVBX. The Meteoritical Society records the Creston fall as an L6 meteorite with a total recovered mass of 688g. Osceola, FL (24 Jan 2016 1527 UTC): This daytime fireball generated 134 eyewitness reports on AMS report number 266 for 2016, with one credible sonic boom report. The fireball traveled roughly NE to SW with a terminus location north of Lake City, FL in sparsely populated, forested countryside. Radar imagery shows distinct and prominent evidence of a significant meteorite fall with radar signatures seen in data from the KJAX and KVAX radars. Searchers at the fall site found that recoveries were restricted to road sites by the difficult terrain, and yet several meteorites were recovered. Evidence indicates that this was a relatively large meteorite fall where most of the meteorites are unrecoverable due to terrain. Osceola is an L6 meteorite with 991 g total mass recovered to date. Mount Blanco, TX (18 Feb 2016 0343 UTC): This event produced only 39 eyewitness reports and is recorded as AMS event #635 for 2016. No

Enantiomer excesses of rare and common sugar derivatives in carbonaceous meteorites

Science.gov (United States)

Cooper, George; Rios, Andro C.

2016-06-01

Biological polymers such as nucleic acids and proteins are constructed of only one—the d or l—of the two possible nonsuperimposable mirror images (enantiomers) of selected organic compounds. However, before the advent of life, it is generally assumed that chemical reactions produced 50:50 (racemic) mixtures of enantiomers, as evidenced by common abiotic laboratory syntheses. Carbonaceous meteorites contain clues to prebiotic chemistry because they preserve a record of some of the Solar System’s earliest (˜4.5 Gy) chemical and physical processes. In multiple carbonaceous meteorites, we show that both rare and common sugar monoacids (aldonic acids) contain significant excesses of the d enantiomer, whereas other (comparable) sugar acids and sugar alcohols are racemic. Although the proposed origins of such excesses are still tentative, the findings imply that meteoritic compounds and/or the processes that operated on meteoritic precursors may have played an ancient role in the enantiomer composition of life’s carbohydrate-related biopolymers.

Enantiomer excesses of rare and common sugar derivatives in carbonaceous meteorites.

Science.gov (United States)

Cooper, George; Rios, Andro C

2016-06-14

Biological polymers such as nucleic acids and proteins are constructed of only one-the d or l-of the two possible nonsuperimposable mirror images (enantiomers) of selected organic compounds. However, before the advent of life, it is generally assumed that chemical reactions produced 50:50 (racemic) mixtures of enantiomers, as evidenced by common abiotic laboratory syntheses. Carbonaceous meteorites contain clues to prebiotic chemistry because they preserve a record of some of the Solar System's earliest (∼4.5 Gy) chemical and physical processes. In multiple carbonaceous meteorites, we show that both rare and common sugar monoacids (aldonic acids) contain significant excesses of the d enantiomer, whereas other (comparable) sugar acids and sugar alcohols are racemic. Although the proposed origins of such excesses are still tentative, the findings imply that meteoritic compounds and/or the processes that operated on meteoritic precursors may have played an ancient role in the enantiomer composition of life's carbohydrate-related biopolymers.

Radioisotope studies of the farmville meteorite using γγ-coincidence spectrometry.

Science.gov (United States)

Howard, Chris; Ferm, Megan; Cesaratto, John; Daigle, Stephen; Iliadis, Christian

2014-12-01

Radionuclides are cosmogenically produced in meteorites before they fall to the surface of the Earth. Measurement of the radioactive decay of such nuclides provides a wealth of information on the irradiation conditions of the meteorite fragment, the intensity of cosmic rays in the inner solar system, and the magnetic activity of the Sun. We report here on the detection of (26)Al using a sophisticated spectrometer consisting of a HPGe detector and a NaI(Tl) annulus. It is shown that modern γ-ray spectrometers represent an interesting alternative to other detection techniques. Data are obtained for a fragment of the Farmville meteorite and compared to results from Geant4 simulations. In particular, we report on optimizing the detection sensitivity by using suitable coincidence gates for deposited energy and event multiplicity. We measured an (26)Al activity of 48.5±3.5dpm/kg for the Farmville meteorite, in agreement with previously reported values for other H chondrites. Copyright © 2014 Elsevier Ltd. All rights reserved.

Laboratory spectroscopy of meteorite samples at UV-vis-NIR wavelengths: Analysis and discrimination by principal components analysis

Science.gov (United States)

Penttilä, Antti; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri

2018-02-01

Meteorite samples are measured with the University of Helsinki integrating-sphere UV-vis-NIR spectrometer. The resulting spectra of 30 meteorites are compared with selected spectra from the NASA Planetary Data System meteorite spectra database. The spectral measurements are transformed with the principal component analysis, and it is shown that different meteorite types can be distinguished from the transformed data. The motivation is to improve the link between asteroid spectral observations and meteorite spectral measurements.

Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars

Science.gov (United States)

McSween, H.Y.; Wyatt, M.B.; Gellert, Ralf; Bell, J.F.; Morris, R.V.; Herkenhoff, K. E.; Crumpler, L.S.; Milam, K.A.; Stockstill, K.R.; Tornabene, L.L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N.A.; Christensen, P.R.; Clark, B. C.; Crisp, J.A.; Des Marais, D.J.; Economou, T.; Farmer, J.D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.; Hamilton, V.E.; Johnson, J. R.; Joliff, B.L.; Klingelhofer, G.; Knudson, A.T.; McLennan, S.; Ming, D.; Moersch, J.E.; Rieder, R.; Ruff, S.W.; Schrorder, C.; de Souza, P.A.; Squyres, S. W.; Wanke, H.; Wang, A.; Yen, A.; Zipfel, J.

2006-01-01

Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times. Copyright 2006 by the American Geophysical Union.

First natural occurrence of coesite

Science.gov (United States)

Chao, E.C.T.; Shoemaker, E.M.; Madsen, B.M.

1960-01-01

Coesite, the high-pressure polymorph of SiO2, hitherto known only as a synthetic compound, is identified as an abundant mineral in sheared Coconino sandstone at Meteor Crater, Arizona. This natural occurrence has important bearing on the recognition of meteorite impact craters in quartz-bearing geologic formations.

Meteorites, Bolides and Comets: A Tale of Inconsistency

Science.gov (United States)

Jakes, P.; Padevet, V.

1992-07-01

-Tuttle, and Leo Minorids to 1739 Zanotti. Geminids were related to asteroid 3200 Phaeton, considered to be an "extinct comet." Spurny [9], using ablation coefficient and penetration depth criteria, found that Geminids (frequently) and Taurids (rarely) contain bolides of types I and II. This may indicate that meteoric showers from "comets" on AAA orbits contain some portion of "rocky" material comparable to chondrites. These observations revive Opik's (1963) idea that comets may be captured in the asteroid belt on AAA orbits and may contain (and supply) chondritic meteorites to the Earth [10]. If the relationship among large solid particles "native to the asteroid belt" and those from the outer solar system can be established, they can be scaled and applied to IDPs. We have studied the records of 292 bolides (Prairie and European networks) with measured terminal velocities. We attempt to use the terminal velocity, calculated density, estimated terminal mass, and mechanical strength to correlate features with the meteorite features. We compare the meteorite fall frequency [11] with the bolide features. Two extreme hypotheses (Table 1) are examined: (A) bolides of types IIIa and IIIb do not have equivalents among the meteorites and (B) all four bolide types have meteoritic equivalents, and only IDPs do not produce bolides (fireballs). If the entry parameters of meteoroids are similar, bodies with lower density should reach terminal velocity at higher altitudes than those with higher density. If it is assumed that fragmentation is the same for dense (I and II) and less dense bodies (IIIa and IIIb), the calculated terminal altitudes show that among the bolides exist materials with lower densities than those of recovered meteorites and that model A of the correlation between meteorite falls and bolide observations is likely [12]. If, however, the less dense bodies were more easily fragmented than denser bodies, the correlation is better for hypothesis B. Table 1, which in the hard

Magnetic properties of tetrataenite-rich meteorites. Pt. 2

International Nuclear Information System (INIS)

Nagata, T.; Funaki, M.; Danon, J.

1985-01-01

Magnetic hysteresis and thermomagnetic characteristics of St. Severin (LL 6 ), Appley Bridge (LL 6 ) and Tuxtuac (LL 5 ) chondrites, which contain tetrataenite in their metallic components, are measured and analyzed in comparison with another tetrataenite-rich chondrite, Yamato 74160. The magnetic properties of tetrataenite-rich meteorites are characterized by (a) high magnetic coercive force (H sub(C)) which amounts to 520 Oe for St. Severin and 160 Oe for Appley Bridge, (b) essential flatness up to about 500 0 C and then a sharp irreversible drop down to Curie point of the first-run heating thermomagnetic curve. Both characteristic features are broken down to the ordinary features of disordered taenite by a breakdown of tetrataenite structure at elevated temperatures beyond the order-disorder transition temperature. The natural remanent magnetization (NRM) of tetrataenite-rich meteorites is extremely stable against AF-demagnetization and other magnetic disturbances because of the high magnetic coercivity of tetrataenite. The breakdown processes of ordered tetrataenite structure by heat treatments are experimentally pursued for the purpose of research of a possible formation process of tetrataenite phase in meteorites. (Author) [pt

Tungsten isotopic compositions of iron meteorites: Chronological constraints vs. cosmogenic effects

Science.gov (United States)

Markowski, A.; Quitté, G.; Halliday, A. N.; Kleine, T.

2006-02-01

High-precision W isotopic compositions are presented for 35 iron meteorites from 7 magmatic groups (IC, IIAB, IID, IIIAB, IIIF, IVA, and IVB) and 3 non-magmatic groups (IAB, IIICD, and IIE). Small but resolvable isotopic variations are present both within and between iron meteorite groups. Variations in the 182W/ 184W ratio reflect either time intervals of metal-silicate differentiation, or result from the burnout of W isotopes caused by a prolonged exposure to galactic cosmic rays. Calculated apparent time spans for some groups of magmatic iron meteorites correspond to 8.5 ± 2.1 My (IID), 5.1 ± 2.3 My (IIAB), and 5.3 ± 1.3 My (IVB). These time intervals are significantly longer than those predicated from models of planetesimal accretion. It is shown that cosmogenic effects can account for a large part of the W isotopic variation. No simple relationship exists with exposure ages, compromising any reliable method of correction. After allowance for maximum possible cosmogenic effects, it is found that there is no evidence that any of the magmatic iron meteorites studied here have initial W isotopic compositions that differ from those of Allende CAIs [ ɛ182W = - 3.47 ± 0.20; [T. Kleine, K. Mezger, H. Palme, E. Scherer and C. Münker, Early core formation in asteroids and late accretion of chondrite parent bodies: evidence from 182Hf- 182W in CAIs, metal-rich chondrites and iron meteorites, Geochim. Cosmochim. Acta (in press)]. Cosmogenic corrections cannot yet be made with sufficient accuracy to obtain highly precise ages for iron meteorites. Some of the corrected ages nevertheless require extremely early metal-silicate segregation no later than 1 My after formation of CAIs. Therefore, magmatic iron meteorites appear to provide the best examples yet identified of material derived from the first planetesimals that grew by runaway growth, as modelled in dynamic simulations. Non-magmatic iron meteorites have a more radiogenic W isotopic composition than magmatic

Scaling analysis of meteorite shower mass distributions

DEFF Research Database (Denmark)

Oddershede, Lene; Meibom, A.; Bohr, Jakob

1998-01-01

Meteorite showers are the remains of extraterrestrial objects which are captivated by the gravitational field of the Earth. We have analyzed the mass distribution of fragments from 16 meteorite showers for scaling. The distributions exhibit distinct scaling behavior over several orders of magnetude......; the observed scaling exponents vary from shower to shower. Half of the analyzed showers show a single scaling region while the orther half show multiple scaling regimes. Such an analysis can provide knowledge about the fragmentation process and about the original meteoroid. We also suggest to compare...... the observed scaling exponents to exponents observed in laboratory experiments and discuss the possibility that one can derive insight into the original shapes of the meteoroids....

Leakage of active crater lake brine through the north flank at Rincon de la Vieja volcano, northwest Costa Rica, and implications for crater collapse

Science.gov (United States)

Kempter, K.A.; Rowe, G.L.

2000-01-01

The Active Crater at Rincon de la Vieja volcano, Costa Rica, reaches an elevation of 1750 m and contains a warm, hyper-acidic crater lake that probably formed soon after the eruption of the Rio Blanco tephra deposit approximately 3500 years before present. The Active Crater is buttressed by volcanic ridges and older craters on all sides except the north, which dips steeply toward the Caribbean coastal plains. Acidic, above-ambient-temperature streams are found along the Active Crater's north flank at elevations between 800 and 1000 m. A geochemical survey of thermal and non-thermal waters at Rincon de la Vieja was done in 1989 to determine whether hyper-acidic fluids are leaking from the Active Crater through the north flank, affecting the composition of north-flank streams. Results of the water-chemistry survey reveal that three distinct thermal waters are found on the flanks of Rincon de la Vieja volcano: acid chloride-sulfate (ACS), acid sulfate (AS), and neutral chloride (NC) waters. The most extreme ACS water was collected from the crater lake that fills the Active Crater. Chemical analyses of the lake water reveal a hyper-acidic (pH ~ 0) chloride-sulfate brine with elevated concentrations of calcium, magnesium, aluminum, iron, manganese, copper, zinc, fluorine, and boron. The composition of the brine reflects the combined effects of magmatic degassing from a shallow magma body beneath the Active Crater, dissolution of andesitic volcanic rock, and evaporative concentration of dissolved constituents at above-ambient temperatures. Similar cation and anion enrichments are found in the above-ambient-temperature streams draining the north flank of the Active Crater. The pH of north-flank thermal waters range from 3.6 to 4.1 and chloride:sulfate ratios (1.2-1.4) that are a factor of two greater than that of the lake brine (0.60). The waters have an ACS composition that is quite different from the AS and NC thermal waters that occur along the southern flank of Rincon

Biomarkers and Microfossils in the Murchison, Rainbow, and Tagish Lake meteorites

Science.gov (United States)

Hoover, Richard B.; Jerman, Gregory A.; Rozanov, Alexei Y.; Davies, Paul C.

2003-02-01

During the past six years, we have conducted extensive scanning electron and optical microscopy investigations and x-ray analysis to determine the morphology, life cycle processes, and elemental distributions in living and fossil cyanobacteria, bacteria, archaea, fungi, and algae sampled from terrestrial environments relevant to Astrobiology. Biominerals, pseudomorphs and microfossils have been studied for diverse microbial groups in various states of preservation in many types of rocks (e.g., oil shales, graphites, shungites, bauxites, limestones, pyrites, phosphorites, and hydrothermal vent chimneys). Results of these studies have been applied to the search for biosignatures in carbonaceous chondrites, stony, and nickel iron meteorites. We review important biomarkers found in terrestrial rocks and meteorites and present additional evidence for the existence of indigenous bacterial microfossils in-situ in freshly fractured surfaces of the Murchison, Rainbow and Tagish Lake carbonaceous meteorites. We provide secondary and backscatter electron images and spectral data obtained with Field Emission and Environmental Scanning Electron Microscopes of biominerals and microfossils. We discuss techniques for discriminating indigenous microfossils from recent terrestrial contaminants. Images are provided of framboidal magnetites in oil shales and meteorites and images and 2D x-ray maps are shown of bacterial microfossils embedded in the mineral matrix of the Murchison, Rainbow and Tagish Lake Carbonaceous Meteorites. These microfossils exhibit characteristics that preclude their interpretation as post-arrival contaminants and we interpret them as indigenous biogenic remains.

Wrinkle Ridges and Young Fresh Crater

Science.gov (United States)

2002-01-01

(Released 10 May 2002) The Science Wrinkle ridges are a very common landform on Mars, Mercury, Venus, and the Moon. These ridges are linear to arcuate asymmetric topographic highs commonly found on smooth plains. The origin of wrinkle ridges is not certain and two leading hypotheses have been put forth by scientists over the past 40 years. The volcanic model calls for the extrusion of high viscosity lavas along linear conduits. This thick lava accumulated over these conduits and formed the ridges. The other model is tectonic and advocates that the ridges are formed by compressional faulting and folding. Today's THEMIS image is of the ridged plains of Lunae Planum located between Kasei Valles and Valles Marineris in the northern hemisphere of the planet. Wrinkle ridges are found mostly along the eastern side of the image. The broadest wrinkle ridges in this image are up to 2 km wide. A 3 km diameter young fresh crater is located near the bottom of the image. The crater's ejecta blanket is also clearly seen surrounding the sharp well-defined crater rim. These features are indicative of a very young crater that has not been subjected to erosional processes. The Story The great thing about the solar system is that planets are both alike and different. They're all foreign enough to be mysterious and intriguing, and yet familiar enough to be seen as planetary 'cousins.' By comparing them, we can learn a lot about how planets form and then evolve geologically over time. Crinkled over smooth plains, the long, wavy raised landforms seen here are called 'wrinkle ridges,' and they've been found on Mars, Mercury, Venus, and the Moon - that is, on rocky bodies that are a part of our inner solar system. We know from this observation that planets (and large-enough moons) follow similar processes. What we don't know for sure is HOW these processes work. Scientists have been trying to understand how wrinkle ridges form for 40 years, and they still haven't reached a conclusion. That

De Magnete et Meteorite: Cosmically Motivated Materials

Energy Technology Data Exchange (ETDEWEB)

Lewis, LH; Pinkerton, FE; Bordeaux, N; Mubarok, A; Poirier, E; Goldstein, JI; Skomski, R; Barmak, K

2014-01-01

Meteorites, likely the oldest source of magnetic material known to mankind, are attracting renewed interest in the science and engineering community. Worldwide focus is on tetrataenite, a uniaxial ferromagnetic compound with the tetragonal L1(0) crystal structure comprised of nominally equiatomic Fe-Ni that is found naturally in meteorites subjected to extraordinarily slow cooling rates, as low as 0.3 K per million years. Here, the favorable permanent magnetic properties of bulk tetrataenite derived from the meteorite NWA 6259 are quantified. The measured magnetization approaches that of Nd-Fe-B (1.42 T) and is coupled with substantial anisotropy (1.0-1.3 MJ/m(3)) that implies the prospect for realization of technologically useful coercivity. A highly robust temperature dependence of the technical magnetic properties at an elevated temperature (20-200 degrees C) is confirmed, with a measured temperature coefficient of coercivity of -0.005%/ K, over one hundred times smaller than that of Nd-Fe-B in the same temperature range. These results quantify the extrinsic magnetic behavior of chemically ordered tetrataenite and are technologically and industrially significant in the current context of global supply chain limitations of rare-earth metals required for present-day high-performance permanent magnets that enable operation of a myriad of advanced devices and machines.

Stratigraphic architecture of bedrock reference section, Victoria Crater, Meridiani Planum, Mars

Science.gov (United States)

Edgar, Lauren A.; Grotzinger, John P.; Hayes, Alex G.; Rubin, David M.; Squyres, Steve W.; Bell, James F.; Herkenhoff, Ken E.

2012-01-01

The Mars Exploration Rover Opportunity has investigated bedrock outcrops exposed in several craters at Meridiani Planum, Mars, in an effort to better understand the role of surface processes in its geologic history. Opportunity has recently completed its observations of Victoria crater, which is 750 m in diameter and exposes cliffs up to ~15 m high. The plains surrounding Victoria crater are ~10 m higher in elevation than those surrounding the previously explored Endurance crater, indicating that the Victoria crater exposes a stratigraphically higher section than does the Endurance crater; however, Victoria strata overlap in elevation with the rocks exposed at the Erebus crater. Victoria crater has a well-developed geomorphic pattern of promontories and embayments that define the crater wall and that reveal thick bedsets (3–7m) of large-scale cross-bedding, interpreted as fossil eolian dunes. Opportunity was able to drive into the crater at Duck Bay, located on the western margin of Victoria crater. Data from the Microscopic Imager and Panoramic Camera reveal details about the structures, textures, and depositional and diagenetic events that influenced the Victoria bedrock. A lithostratigraphic subdivision of bedrock units was enabled by the presence of a light-toned band that lines much of the upper rim of the crater. In ascending order, three stratigraphic units are named Lyell, Smith, and Steno; Smith is the light-toned band. In the Reference Section exposed along the ingress path at Duck Bay, Smith is interpreted to represent a zone of diagenetic recrystallization; however, its upper contact also coincides with a primary erosional surface. Elsewhere in the crater the diagenetic band crosscuts the physical stratigraphy. Correlation with strata present at nearby promontory Cape Verde indicates that there is an erosional surface at the base of the cliff face that corresponds to the erosional contact below Steno. The erosional contact at the base of Cape Verde

The Organic Content of the Tagish Lake Meteorite

Science.gov (United States)

Pizzarello, Sandra; Huang, Yongsong; Becker, Luann; Poreda, Robert J.; Nieman, Ronald A.; Cooper, George; Williams, Michael

2001-01-01

The Tagish Lake meteorite felt last year on a frozen take in Canada and may provide the most pristine material of its kind. Analyses have now shown this carbonaceous chondrite to contain a suite of soluble organic compounds (approximately 100 parts per million) that includes mono- and dicarboxylic acids, dicarboximides, pyridine carboxylic acids, a sulfonic acid, and both aliphatic and aromatic hydrocarbons. The insoluble carbon exhibits exclusive aromatic character, deuterium enrichment, and fullerenes containing 'planetary' helium and argon. The findings provide insight into an outcome of early solar chemical evolution that differs from any seen so far in meteorites.

The cali meteorite fell: A new H/L ordinary chondrite

Science.gov (United States)

Rodriguez, J.M.T.; Llorca, J.; Rubin, A.E.; Grossman, J.N.; Sears, D.W.G.; Naranjo, M.; Bretzius, S.; Tapia, M.; Sepulveda, M.H.G.

2009-01-01

The fall of the Cali meteorite took place on 6 July 2007 at 16 h 32 ?? 1 min local time (21 h 32 ?? 1 min UTC). A daylight fireball was witnessed by hundreds of people in the Cauca Valley in Colombia from which 10 meteorite samples with a total mass of 478 g were recovered near 3??24.3'N, 76??30.6'W. The fireball trajectory and radiant have been reconstructed with moderate accuracy. From the computed radiant and from considering various plausible velocities, we obtained a range of orbital solutions that suggest that the Cali progenitor meteoroid probably originated in the main asteroid belt. Based on petrography, mineral chemistry, magnetic susceptibility, fhermoluminescence, and bulk chemistry, the Cali meteorite is classified as an H/L4 ordinary chondrite breccia.

Cosmogenic Radionuclides in Antarctic Meteorites: Preliminary Results on Terrestrial Ages and Temporal Phenomena

Science.gov (United States)

Michlovich, E.; Vogt, S.; Wolf, S. F.; Elmore, D.; Lipschutz, M. E.

1993-07-01

Since 1969, more than 15,000 meteorites have been recovered from various sites in Antarctica. Differences have been reported between the Antarctic populations and the population of non-Antarctic meteorites in volatile trace- element content, thermoluminescence properties, physical size, and relative distribution of meteorite type [1]. Lipschutz and Samuels [2] developed a method based upon multivariate linear and logistic regression that they applied to interpret trace-element content in Antarctic and non-Antarctic meteorites, showing that the two populations can be chemically distinguished. Since Antarctic meteorites have, on the whole, much longer terrestrial ages than non-Antarctic falls, such differences have been used to support the notion that the flux of meteorites sampled by the Earth has changed in the recent past. A subsequent study [3] showed a statistically significant difference in trace-element content between meteorites from Victoria Land and those found in Queen Maud Land, two groups that seem to have different terrestrial age distributions. Changes in meteorite flux patterns on the order of 60 yr are indicated from a study of Cluster 1 vs. non-Cluster 1 falls [4]. Rapid fluctuations would almost certainly require the existence of co-orbital meteoroid streams, an idea that has been criticized by some [5] on dynamical grounds. To quantify the discussion of a temporal dependence of meteorite flux patterns, and to continue systematic study of Antarctic meteorites, we have measured the contents of the cosmogenic radionuclides ^10Be and ^26Al in the bulk phase, and ^36Cl in the metal phase, of 40 Antarctic specimens that are from the same suite of samples analyzed in the trace-element studies and that were chosen to minimize any chances of paired meteorites. The means and standard deviations of ^10Be and ^26Al activities are 16.4 +/- 3.5 and 48 +/- 8 dpm/kg respectively. Correction for cosmic ray exposure [6,7] and terrestrial ages allows us to estimate

Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

International Nuclear Information System (INIS)

Reedy, R.C.

1984-01-01

A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm -2 . Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures

The Morphology of Craters on Mercury: Results from MESSENGER Flybys

Science.gov (United States)

Barnouin, Oliver S.; Zuber, Maria T.; Smith, David E.; Neumann, Gregory A.; Herrick, Robert R.; Chappelow, John E.; Murchie, Scott L.; Prockter, Louise M.

2012-01-01

Topographic data measured from the Mercury Laser Altimeter (MLA) and the Mercury Dual Imaging System (MDIS) aboard the MESSENGER spacecraft were used for investigations of the relationship between depth and diameter for impact craters on Mercury. Results using data from the MESSENGER flybys of the innermost planet indicate that most of the craters measured with MLA are shallower than those previously measured by using Mariner 10 images. MDIS images of these same MLA-measured craters show that they have been modified. The use of shadow measurement techniques, which were found to be accurate relative to the MLA results, indicate that both small bowl-shaped and large complex craters that are fresh possess depth-to-diameter ratios that are in good agreement with those measured from Mariner 10 images. The preliminary data also show that the depths of modified craters are shallower relative to fresh ones, and might provide quantitative estimates of crater in-filling by subsequent volcanic or impact processes. The diameter that defines the transition from simple to complex craters on Mercury based on MESSENGER data is consistent with that reported from Mariner 10 data.

Meteoritic Input of Amino Acids and Nucleobases: Methodology and Implications for the Origins of Life

Science.gov (United States)

Burton, Aaron S.; Stern, Jennifer C.; Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

2012-01-01

The discoveries of amino acids of extraterrestrial origin in many meteorites over the last 40 years have revolutionized the Astrobiology field. A variety of non-terrestrial amino acids similar to those found in life on Earth have been detected in meteorites. A few amino acids have even been found with chiral excesses, suggesting that meteorites could have contributed to the origin of homochirality in life on Earth. In addition to amino acids, which have been productively studied for years, sugar-like molecules, activated phosphates, and nucleobases have also been determined to be indigenous to numerous meteorites. Because these molecules are essential for life as we know it, and meteorites have been delivering them to the Earth since accretion, it is plausible that the origin(s) of life on Earth were aided by extraterrestrially-synthesized molecules. Understanding the origins of life on Earth guides our search for life elsewhere, helping to answer the question of whether biology is unique to Earth. This tutorial review focuses on meteoritic amino acids and nucleobases, exploring modern analytical methods and possible formation mechanisms. We will also discuss the unique window that meteorites provide into the chemistry that preceded life on Earth, a chemical record we do not have access to on Earth due to geologic recycling of rocks and the pervasiveness of biology across the planet. Finally, we will address the future of meteorite research, including asteroid sample return mIssIons.

On possible parent bodies of Innisfree, Lost City and Prgibram meteorites.

Science.gov (United States)

Rozaev, A. E.

1994-12-01

Minor planets 1981 ET3 and Seleucus are possible parent bodies of Innisfree and Lost City meteorites, asteroid Mithra is the most probable source of Prgibram meteorite. The conclusions are based on the Southworth - Hawkins criterion with taking into account of the motion constants (Tisserand coefficient, etc.) and minimal distances between orbits at present time.

Spectral analysis of meteorites ablated in a wind tunnel

Science.gov (United States)

Drouard, A.; Vernazza, P.; Loehle, S.; Gattacceca, J.; Zander, T.; Eberhart, M.; Meindl, A.; Oefele, R.; Vaubaillon, J.; Colas, F.

2017-09-01

Recently and for the very first time, experiments simulating vaporization of a meteorite sample were performed in a wind tunnel near Stuttgart with the specific aim to record emission spectra of the vaporized material. Using a high enthalpy air plasma flow for modeling an equivalent air friction of an entry speed of about 10 km/s, three meteorite types (H, CM and HED) and two meteoritical analogues (basalt and argillite) were ablated and high resolution spectra were recorded simultaneously. After the identification of all atomic lines, we per- formed a detailed study of our spectra using two approaches: (i) by direct comparison of multiplet in- tensities between the samples and (ii) by computation of a synthetic spectrum to constrain some physical parameters (temperature, elemental abundance). Finally, we compared our results to the elemental composition of our samples and we determined how much compositional information can be retrieved for a given meteor using visible sectroscopy.

Morphological indicators of a mascon beneath Ceres' largest crater, Kerwan

Science.gov (United States)

Bland, Michael T.; Ermakov, Anton; Raymond, Carol A.; Williams, David A.; Bowling, Tim J.; Preusker, F.; Park, Ryan S.; Marchi, Simone; Castillo-Rogez, Julie C.; Fu, R.R.; Russell, Christopher T.

2018-01-01

Gravity data of Ceres returned by the National Aeronautics and Space Administration's Dawn spacecraft is consistent with a lower density crust of variable thickness overlying a higher density mantle. Crustal thickness variations can affect the long‐term, postimpact modification of impact craters on Ceres. Here we show that the unusual morphology of the 280 km diameter crater Kerwan may result from viscous relaxation in an outer layer that thins substantially beneath the crater floor. We propose that such a structure is consistent with either impact‐induced uplift of the high‐density mantle beneath the crater or from volatile loss during the impact event. In either case, the subsurface structure inferred from the crater morphology is superisostatic, and the mass excess would result in a positive Bouguer anomaly beneath the crater, consistent with the highest‐degree gravity data from Dawn. Ceres joins the Moon, Mars, and Mercury in having basin‐associated gravity anomalies, although their origin may differ substantially.

Morphological Indicators of a Mascon Beneath Ceres's Largest Crater, Kerwan

Science.gov (United States)

Bland, M. T.; Ermakov, A. I.; Raymond, C. A.; Williams, D. A.; Bowling, T. J.; Preusker, F.; Park, R. S.; Marchi, S.; Castillo-Rogez, J. C.; Fu, R. R.; Russell, C. T.

2018-02-01

Gravity data of Ceres returned by the National Aeronautics and Space Administration's Dawn spacecraft is consistent with a lower density crust of variable thickness overlying a higher density mantle. Crustal thickness variations can affect the long-term, postimpact modification of impact craters on Ceres. Here we show that the unusual morphology of the 280 km diameter crater Kerwan may result from viscous relaxation in an outer layer that thins substantially beneath the crater floor. We propose that such a structure is consistent with either impact-induced uplift of the high-density mantle beneath the crater or from volatile loss during the impact event. In either case, the subsurface structure inferred from the crater morphology is superisostatic, and the mass excess would result in a positive Bouguer anomaly beneath the crater, consistent with the highest-degree gravity data from Dawn. Ceres joins the Moon, Mars, and Mercury in having basin-associated gravity anomalies, although their origin may differ substantially.

AMMONIA IN THE EARLY SOLAR SYSTEM: AN ACCOUNT FROM CARBONACEOUS METEORITES

International Nuclear Information System (INIS)

Pizzarello, S.; Williams, L. B.

2012-01-01

This study presents a survey of abundance distribution and isotopic composition of the ammonia found incorporated in the kerogen-like insoluble material of selected carbonaceous chondrite meteorites; the ammonia was released upon hydrothermal treatment at 300°C and 100 MPa. With the exception of Allende, a metamorphosed and highly altered stone, all the insoluble organic materials (IOM) of the meteorites analyzed released significant amounts of ammonia, which varied from over 4 μg mg –1 for the Orgueil IOM to 0.5 μg mg –1 for that of Tagish Lake; the IOM of the pristine Antarctica find GRA95229 remains the most rich in freeable ammonia with 10 μg mg –1 . While the amounts of IOM bound ammonia do not appear to vary between meteorites with a recognizable trend, a possible consequence of long terrestrial exposure of some of the stones, we found that the δ 15 N composition of the ammonia-carrying materials is clearly distinctive of meteorite types and may reflect a preservation of the original 15 N distribution of pre- and proto-solar materials.

Ammonia in the Early Solar System: An Account from Carbonaceous Meteorites

Science.gov (United States)

Pizzarello, S.; Williams, L. B.

2012-04-01

This study presents a survey of abundance distribution and isotopic composition of the ammonia found incorporated in the kerogen-like insoluble material of selected carbonaceous chondrite meteorites; the ammonia was released upon hydrothermal treatment at 300°C and 100 MPa. With the exception of Allende, a metamorphosed and highly altered stone, all the insoluble organic materials (IOM) of the meteorites analyzed released significant amounts of ammonia, which varied from over 4 μg mg-1 for the Orgueil IOM to 0.5 μg mg-1 for that of Tagish Lake; the IOM of the pristine Antarctica find GRA95229 remains the most rich in freeable ammonia with 10 μg mg-1. While the amounts of IOM bound ammonia do not appear to vary between meteorites with a recognizable trend, a possible consequence of long terrestrial exposure of some of the stones, we found that the δ15N composition of the ammonia-carrying materials is clearly distinctive of meteorite types and may reflect a preservation of the original 15N distribution of pre- and proto-solar materials.

U-Pb Dating of Zircons and Phosphates in Lunar Meteorites, Acapulcoites and Angrites

Science.gov (United States)

Zhou, Q.; Zeigler, R. A.; Yin, Q. Z.; Korotev, R. L.; Joliff, B. L.; Amelin, Y.; Marti, K.; Wu, F. Y.; Li, X. H.; Li, Q. L.;

Nanoindenting the Chelyabinsk Meteorite to Learn about Impact Deflection Effects in asteroids

Energy Technology Data Exchange (ETDEWEB)

Moyano-Cambero, Carles E.; Trigo-Rodríguez, Josep M.; Martínez-Jiménez, Marina; Lloro, Ivan [Institute of Space Sciences (IEEC-CSIC), Meteorites, Minor Bodies and Planetary Sciences Group, Campus UAB Bellaterra, c/Can Magrans s/n, 08193 Cerdanyola del Vallès (Barcelona) (Spain); Pellicer, Eva [Departament de Física, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain); Williams, Iwan P. [School of Physics and Astronomy, Queen Mary, University of London, 317 Mile End Road, E1 4NS London (United Kingdom); Blum, Jürgen [Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38106 Braunschweig (Germany); Michel, Patrick [Lagrange Laboratory, University of Nice, CNRS, Côte d’Azur Observatory (France); Küppers, Michael [European Space Agency, European Space Astronomy Centre, P.O. Box 78, Villanueva de la Cañada E-28691 (Spain); Sort, Jordi, E-mail: moyano@ice.csic.es, E-mail: trigo@ice.csic.es [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain)

2017-02-01

The Chelyabinsk meteorite is a highly shocked, low porosity, ordinary chondrite, probably similar to S- or Q-type asteroids. Therefore, nanoindentation experiments on this meteorite allow us to obtain key data to understand the physical properties of near-Earth asteroids. Tests at different length scales provide information about the local mechanical properties of the minerals forming this meteorite: reduced Young’s modulus, hardness, elastic recovery, and fracture toughness. Those tests are also useful to understand the potential to deflect threatening asteroids using a kinetic projectile. We found that the differences in mechanical properties between regions of the meteorite, which increase or reduce the efficiency of impacts, are not a result of compositional differences. A low mean particle size, attributed to repetitive shock, can increase hardness, while low porosity promotes a higher momentum multiplication. Momentum multiplication is the ratio between the change in momentum of a target due to an impact, and the momentum of the projectile, and therefore, higher values imply more efficient impacts. In the Chelyabinsk meteorite, the properties of the light-colored lithology materials facilitate obtaining higher momentum multiplication values, compared to the other regions described for this meteorite. Also, we found a low value of fracture toughness in the shock-melt veins of Chelyabinsk, which would promote the ejection of material after an impact and therefore increase the momentum multiplication. These results are relevant to the growing interest in missions to test asteroid deflection, such as the recent collaboration between the European Space Agency and NASA, known as the Asteroid Impact and Deflection Assessment mission.

Nanoindenting the Chelyabinsk Meteorite to Learn about Impact Deflection Effects in asteroids

International Nuclear Information System (INIS)

Moyano-Cambero, Carles E.; Trigo-Rodríguez, Josep M.; Martínez-Jiménez, Marina; Lloro, Ivan; Pellicer, Eva; Williams, Iwan P.; Blum, Jürgen; Michel, Patrick; Küppers, Michael; Sort, Jordi

2017-01-01

The Chelyabinsk meteorite is a highly shocked, low porosity, ordinary chondrite, probably similar to S- or Q-type asteroids. Therefore, nanoindentation experiments on this meteorite allow us to obtain key data to understand the physical properties of near-Earth asteroids. Tests at different length scales provide information about the local mechanical properties of the minerals forming this meteorite: reduced Young’s modulus, hardness, elastic recovery, and fracture toughness. Those tests are also useful to understand the potential to deflect threatening asteroids using a kinetic projectile. We found that the differences in mechanical properties between regions of the meteorite, which increase or reduce the efficiency of impacts, are not a result of compositional differences. A low mean particle size, attributed to repetitive shock, can increase hardness, while low porosity promotes a higher momentum multiplication. Momentum multiplication is the ratio between the change in momentum of a target due to an impact, and the momentum of the projectile, and therefore, higher values imply more efficient impacts. In the Chelyabinsk meteorite, the properties of the light-colored lithology materials facilitate obtaining higher momentum multiplication values, compared to the other regions described for this meteorite. Also, we found a low value of fracture toughness in the shock-melt veins of Chelyabinsk, which would promote the ejection of material after an impact and therefore increase the momentum multiplication. These results are relevant to the growing interest in missions to test asteroid deflection, such as the recent collaboration between the European Space Agency and NASA, known as the Asteroid Impact and Deflection Assessment mission.

Summary of results of cratering experiments

International Nuclear Information System (INIS)

Toman, J.

1969-01-01

The use of nuclear excavation as a construction technique for producing harbors, canals, highway cuts, and other large excavations requires a high assurance that the yield and depth of burst selected for the explosive will produce the desired configuration within an acceptable degree of tolerance. Nuclear excavation technology advanced significantly during 1968 as a result of the successful execution of Projects Cabriolet, Buggy, and Schooner. Until these experiments were conducted, the only nuclear data available for designing large excavations were derived from Sedan (100 kt in alluvium), Danny Boy (0.42 kt in basalt), and Sulky (0.090 kt in basalt). Applicable experience has now been extended to include two additional rock types: tuff and porphyritic trachyte, non-homogeneous formations with severe geologic layering, and a nuclear row in hard rock. The continued development of cratering calculations using in situ geophysical measurements and high-pressure test data have provided a means for predicting the cratering characteristics of untested materials. Chemical explosive cratering experiments conducted in the pre-Gondola series during the past several years have been directed toward determining the behavior of weak, wet clay shales. This material is important to nuclear excavation because of potential long-term stability problems which may affect the cratered slopes. (author)

Summary of results of cratering experiments

Energy Technology Data Exchange (ETDEWEB)

Toman, J [Lawrence Radiation Laboratory, Livermore, CA (United States)

1969-07-01

The use of nuclear excavation as a construction technique for producing harbors, canals, highway cuts, and other large excavations requires a high assurance that the yield and depth of burst selected for the explosive will produce the desired configuration within an acceptable degree of tolerance. Nuclear excavation technology advanced significantly during 1968 as a result of the successful execution of Projects Cabriolet, Buggy, and Schooner. Until these experiments were conducted, the only nuclear data available for designing large excavations were derived from Sedan (100 kt in alluvium), Danny Boy (0.42 kt in basalt), and Sulky (0.090 kt in basalt). Applicable experience has now been extended to include two additional rock types: tuff and porphyritic trachyte, non-homogeneous formations with severe geologic layering, and a nuclear row in hard rock. The continued development of cratering calculations using in situ geophysical measurements and high-pressure test data have provided a means for predicting the cratering characteristics of untested materials. Chemical explosive cratering experiments conducted in the pre-Gondola series during the past several years have been directed toward determining the behavior of weak, wet clay shales. This material is important to nuclear excavation because of potential long-term stability problems which may affect the cratered slopes. (author)

Rock spatial densities on the rims of the Tycho secondary craters in Mare Nectaris

Science.gov (United States)

Basilevsky, A. T.; Michael, G. G.; Kozlova, N. A.

2018-04-01

The aim of this work is to check whether the technique of estimation of age of small lunar craters based on spatial density of rock boulders on their rims described in Basilevsky et al. (2013, 2015b) and Li et al. (2017) for the craters rock counts on the rims of four craters having diameters 1000, 1100, 1240 and 1400 m located in Mare Nectaris. These craters are secondaries of the primary crater Tycho, whose age was found to be 109 ± 4 Ma (Stoffler and Ryder, 2001) so this may be taken as the age of the four craters, too. Using the dependence of the rock spatial densities at the crater rims on the crater age for the case of mare craters (Li et al., 2017) our measured rock densities correspond to ages from ∼100 to 130 Ma. These estimates are reasonably close to the given age of the primary crater Tycho. This, in turn, suggests that this technique of crater age estimation is applicable to craters up to ∼1.5 km in diameter. For the four considered craters we also measured their depth/diameter ratios and the maximum angles of the crater inner slopes. For the considered craters it was found that with increasing crater diameter, the depth/diameter ratios and maximum angles of internal slopes increase, but the values of these parameters for specific craters may deviate significantly from the general trends. The deviations probably result from some dissimilarities in the primary crater geometries, that may be due to crater to crater differences in characteristics of impactors (e.g., in their bulk densities) and/or differences in the mechanical properties of the target. It may be possible to find secondaries of crater Tycho in the South pole area and, if so, they may be studied to check the specifics and rates of the rock boulder degradation in the lunar polar environment.

Some Studies of Terrestrial Impact Cratering Rate

Directory of Open Access Journals (Sweden)

Jetsu L.

2011-06-01

Full Text Available In 1984, a 28.4 Myr periodicity was detected in the ages of terrestrial impact craters and a 26 Myr periodicity in the epochs of mass extinctions of species. Periodic comet showers from the Oort cloud seemed to cause catastrophic events linked to mass extinctions of species. Our first study revealed that the only significant detected periodicity is the “human signal” caused by the rounding of these data into integer numbers. The second study confirmed that the original 28.4 Myr periodicity detection was not significant. The third study revealed that the quality and the quantity of the currently available data would allow detection of real periodicity only if all impacts have been periodic, which cannot be the case. The detection of a periodic signal, if present, requires that more craters should be discovered and the accuracy of age estimates improved. If we sometimes will be able to find the difference between the craters caused by asteroid and comet impacts, the aperiodic component could be removed. The lunar impact craters may eventually provide the required supplementary data.

The evolution of meteorites and planets from a hot nebula

Directory of Open Access Journals (Sweden)

Donald H. Tarling

2015-06-01

Full Text Available Meteorites have a hot origin as planetary materials derive from a supernova, similar to SN1987A, and were acquired by a nearby nova, the Sun. The supernova plasmas became zoned around the nova, mainly by their electromagnetic properties. Carbon and carbide dusts condensed first, followed, within the Inner Planetary Zone, by Ca–Mg–Al oxides and then by iron and nickel metal droplets. In the inner Asteroid Belt, the metals aggregated into clumps as they solidified but over a much longer time in the Inner Zone. ‘Soft’ collisions formed larger (<∼20 km objects in the Asteroid Belt; in the Inner Zone these aggregated forming proto-planetary cores during inwards orbital migration. In the Asteroid Belt, glassy olivines condensed, followed more open lattice minerals growing grew primarily by diffusion. Brittle silicate crystals were comminuted and only aggregated into the carbonaceous meteorites when water–ices formed. The inner planets differentiated by at least 4.4 Ga. Jupiter and the outer planets grew on asteroidal bodies thrown out into freezing water vapours and only formed by 4.1 Ga, resulting in the Late Heavy Bombardment, initially by meteoritic materials and later supplemented by ices from, and beyond, the Asteroid Belt. Critical factors are the properties of very high temperature supernova plasmas, the duration of the molten iron phase in the inner zone. Evidence usually quoted for a cold origin derives from late stage processes in hot meteorite evolution. While highly speculative, it is shown that meteorites and planets can be formed by known processes as supernova plasmas cool.

The formation and the evolution process of the Jilin meteorite

International Nuclear Information System (INIS)

Duyang, Z.Y.

1983-01-01

Based on the data from an integrated study by a multidisciplinary group on the Jilin meteorite, we discuss the following aspects concerning its formation and evolution: (1) The fractionation-condensation of the solar nebula was examined based on the condensation and solidification age and the mineral composition of the Jilin meteorite. (2) The thermometamorphic history of the Jilin parent body was discussed based on the data on the loss of rare gases, the chemical composition of the whole rock, the self-purification of rare-earth elements and the composition stability of olivine and orthopyroxene. (3) The cooling process of the Jilin parent body was analyzed according to the Ni content and the width of taenite, and the retentivity of argon and fission tracks in the minerals. (4) The breakup of the Jilin parent body and its cosmic ray irradiation history: Based on the measurements of the cosmogenic nuclides as He 3 , Ne/sup 20,21,22/, Ar 38 , Na 22 , Al 26 , Mn 54 , Mn 53 , Co 60 etc., a two-stage model of the irradiation history of the Jilin meteorite was proposed. From the data on the Jilin meteorite parent body of the first stage (the age = 10--11 MY and r = 10 m) and that of the second stage (the age = 0.3--0.5 MY and r = 80--90 cm). The relative positions of samples in the parent body, their burial depths as well as the post-atmospheric loss by ignition were determined. (5) The falling process of the Jilin meteorite: The orbits of the Jilin meteor in the solar system and in the atmosphere, and its falling process were discussed

Magnetic, in situ, mineral characterization of Chelyabinsk meteorite thin section

Science.gov (United States)

Nabelek, Ladislav; Mazanec, Martin; Kdyr, Simon; Kletetschka, Gunther

2015-06-01

Magnetic images of Chelyabinsk meteorite's (fragment F1 removed from Chebarkul lake) thin section have been unraveled by a magnetic scanning system from Youngwood Science and Engineering (YSE) capable of resolving magnetic anomalies down to 10-3 mT range from about 0.3 mm distance between the probe and meteorite surface (resolution about 0.15 mm). Anomalies were produced repeatedly, each time after application of magnetic field pulse of varying amplitude and constant, normal or reversed, direction. This process resulted in both magnetizing and demagnetizing of the meteorite thin section, while keeping the magnetization vector in the plane of the thin section. Analysis of the magnetic data allows determination of coercivity of remanence (Bcr) for the magnetic sources in situ. Value of Bcr is critical for calculating magnetic forces applicable during missions to asteroids where gravity is compromised. Bcr was estimated by two methods. First method measured varying dipole magnetic field strength produced by each anomaly in the direction of magnetic pulses. Second method measured deflections of the dipole direction from the direction of magnetic pulses. Bcr of magnetic sources in Chelyabinsk meteorite ranges between 4 and 7 mT. These magnetic sources enter their saturation states when applying 40 mT external magnetic field pulse.

Floor-fractured craters on Ceres and implications for interior processes

Science.gov (United States)

Buczkowski, Debra; Schenk, Paul M.; Scully, Jennifer E. C.; Park, Ryan; Preusker, Frank; Raymond, Carol; Russell, Christopher T.

2016-10-01

Several of the impact craters on Ceres have patterns of fractures on their floors. These fractures appear similar to those found within a class of lunar craters referred to as Floor-Fractured Craters (FFCs) [Schultz, 1976].Lunar FFCs are characterized by anomalously shallow floors cut by radial, concentric, and/or polygonal fractures, and have been classified into crater classes, Types 1 through 6, based on their morphometric properties [Schultz, 1976; Jozwiak et al, 2012, 2015]. Models for their formation have included both floor uplift due to magmatic intrusion below the crater or floor shallowing due to viscous relaxation. However, the observation that the depth versus diameter (d/D) relationship of the FFCs is distinctly shallower than the same association for other lunar craters supports the hypotheses that the floor fractures form due to shallow magmatic intrusion under the crater [Jozwiak et al, 2012, 2015].FFCs have also been identified on Mars [Bamberg et al., 2014]. Martian FFCs exhibit morphological characteristics similar to the lunar FFCs, and analyses suggest that the Martian FCCs also formed due to volcanic activity, although heavily influenced by interactions with groundwater and/or ice.We have cataloged the Ceres FFCs according to the classification scheme designed for the Moon. Large (>50 km) Ceres FFCs are most consistent with Type 1 lunar FFCs, having deep floors, central peaks, wall terraces, and radial and/or concentric fractures. Smaller craters on Ceres are more consistent with Type 4 lunar FFCs, having less-pronounced floor fractures and a v-shaped moats separating the wall scarp from the crater interior.An analysis of the d/D ratio for Ceres craters shows that, like lunar FFCs, the Ceres FFCs are anomalously shallow. This suggests that the fractures on the floor of Ceres FFCs may be due the intrusion of a low-density material below the craters that is uplifting their floors. While on the Moon and Mars the intrusive material is hypothesized

Population characteristics of submicrometer-sized craters on regolith particles from asteroid Itokawa

Science.gov (United States)

Matsumoto, Toru; Hasegawa, S.; Nakao, S.; Sakai, M.; Yurimoto, H.

2018-03-01

We investigated impact crater structures on regolith particles from asteroid Itokawa using scanning electron microscopy. We observed the surfaces of 51 Itokawa particles, ranging from 15 μm to 240 μm in size. Craters with average diameters ranging from 10 nm to 2.8 μm were identified on 13 Itokawa particles larger than 80 μm. We examined the abundance, spatial distribution, and morphology of approximately 900 craters on six Itokawa particles. Craters with sizes in excess of 200 nm are widely dispersed, with spatial densities from 2.6 μm2 to 4.5 μm2; a fraction of the craters was locally concentrated with a density of 0.1 μm2. The fractal dimension of the cumulative crater diameters ranges from 1.3 to 2.3. Craters of several tens of nanometers in diameter exhibit pit and surrounding rim structures. Craters of more than 100 nm in diameter commonly have melted residue at their bottom. These morphologies are similar to those of submicrometer-sized craters on lunar regolith. We estimated the impactor flux on Itokawa regolith-forming craters, assuming that the craters were accumulated during direct exposure to the space environment for 102 to 104 yr. The range of impactor flux onto Itokawa particles is estimated to be at least one order of magnitude higher than the interplanetary dust flux and comparable to the secondary impact flux on the Moon. This indicates that secondary ejecta impacts are probably the dominant cratering process in the submicrometer range on Itokawa regolith particles, as well as on the lunar surface. We demonstrate that secondary submicrometer craters can be produced anywhere in centimeter- to meter-sized depressions on Itokawa's surface through primary interplanetary dust impacts. If the surface unevenness on centimeter to meter scales is a significant factor determining the abundance of submicrometer secondary cratering, the secondary impact flux could be independent of the overall shapes or sizes of celestial bodies, and the secondary

Analysis of Košice Meteorite by Mössbauer Spectroscopy

Science.gov (United States)

Sitek, Jozef; Dekan, Július; Sedlačková, Katarína

2016-07-01

The 57Fe Mössbauer spectroscopy method was used to investigate iron-containing compounds in town Košice meteorite fallen on the territory of Slovakia in February 2010. The results showed that the Mössbauer spectra consisted of magnetic and non-magnetic components related to different iron-bearing phases. The non-magnetic phase includes olivine, pyroxene and traces of Fe3+ phase and the magnetic component comprises troilite (FeS) and iron-rich Fe-Ni alloy with hyperfine magnetic field typical for kamacite. Samples from meteorite were obtained in powder from different depths to inspect its heterogeneous composition. The content of kamacite increases to the detriment of troilite from the surface toward the centre of the sample. Measurements at liquid nitrogen temperature confirmed phase composition of investigated meteorite. Main constituent elements of studied samples were also determined by X-ray fluorescence analysis.

Are pre-crater mounds gas-inflated?

Science.gov (United States)

Leibman, Marina; Kizyakov, Alexandr; Khomutov, Artem; Dvornikov, Yury; Babkina, Elena; Arefiev, Stanislav; Khairullin, Rustam

2017-04-01

Gas-emission craters (GEC) on Yamal peninsula, which occupied minds of researches for the last couple of years since first discovered in 2014, appeared to form on the place of specifically shaped mounds. There was a number of hypotheses involving pingo as an origin of these mounds. This arouse an interest in mapping pingo thus marking the areas of GEC formation risk. Our field research allows us to suggest that remote-sensing-based mapping of pingo may result in mix up of mounds of various origin. Thus, we started with classification of the mounds based on remote-sensing, field observations and survey from helicopter. Then we compared indicators of mounds of various classes to the properties of pre-crater mounds to conclude on their origin. Summarizing field experience, there are three main mound types on Yamal. (1) Outliers (remnant hills), separated from the main geomorphic landform by erosion. Often these mounds comprise polygonal blocks, kind of "baydzherakh". Their indicators are asymmetry (short gentle slope towards the main landform, and steep slope often descending into a small pond of thermokarst-nivation origin), often quadrangle or conic shape, and large size. (2) Pingo, appear within the khasyrei (drain lake basin); often are characterized by open cracks resulting from expansion of polygonal network formed when re-freezing of lake talik prior to pingo formation; old pingo may bear traces of collapse on the top, with depression which differs from the GEC by absence of parapet. (3) Frost-heave mounds (excluding pingo) may form on deep active layer, reducing due to moss-peat formation and forming ice lenses from an active layer water, usually they appear in the drainage hollows, valley bottoms, drain-lake basins periphery. These features are smaller than the first two types of mounds. Their tops as a rule are well vegetated. We were unable to find a single or a set of indicators unequivocally defining any specific mound type, thus indicators of pre-crater

Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites

International Nuclear Information System (INIS)

Cobb, Alyssa K.; Pudritz, Ralph E.

2014-01-01

The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.

PF120916 Piecki fireball and Reszel meteorite fall

Science.gov (United States)

Olech, A.; Żołądek, P.; Tymiński, Z.; Stolarz, M.; Wiśniewski, M.; Bęben, M.; Lewandowski, T.; Polak, K.; Raj, A.; Zaręba, P.

2017-06-01

On September 12, 2016, at 21:44:07 UT, a -9.2±0.5 mag fireball appeared over northeastern Poland. The precise orbit and atmospheric trajectory of the event are presented, based on the data collected by six video stations of the Polish Fireball Network (PFN). The PF120916 Piecki fireball entered the Earth's atmosphere with the velocity of 16.7±0.3 km/s and started to shine at a height of 81.9 ± 0.3 km. Clear deceleration started after first three seconds of the flight, and the terminal velocity of the meteor was only 5.0±0.3 km/s at a height of 26.0 ± 0.2 km. Such a low value of the terminal velocity indicates that fragments with the total mass of around 10-15 kg could survive the atmospheric passage and cause fall of the meteorites. The predicted area of possible meteorite impact is computed and it is located south of Reszel city at the Warmian-Masurian region. The impact area was extensively searched by experienced groups of meteorite hunters, but without any success.

Acoustic fluidization and the scale dependence of impact crater morphology

Science.gov (United States)

Melosh, H. J.; Gaffney, E. S.

1983-01-01

A phenomenological Bingham plastic model has previously been shown to provide an adequate description of the collapse of impact craters. This paper demonstrates that the Bingham parameters may be derived from a model in which acoustic energy generated during excavation fluidizes the rock debris surrounding the crater. Experimental support for the theoretical flow law is presented. Although the Bingham yield stress cannot be computed without detailed knowledge of the initial acoustic field, the Bingham viscosity is derived from a simple argument which shows that it increases as the 3/2 power of crater diameter, consistent with observation. Crater collapse may occur in material with internal dissipation Q as low as 100, comparable to laboratory observations of dissipation in granular materials. Crater collapse thus does not require that the acoustic field be regenerated during flow.

Crater relaxation on Titan aided by low thermal conductivity sand infill

Science.gov (United States)

Schurmeier, Lauren R.; Dombard, Andrew J.

2018-05-01

Titan's few impact craters are currently many hundreds of meters shallower than the depths expected. Assuming these craters initially had depths equal to that of similar-size fresh craters on Ganymede and Callisto (moons of similar size, composition, and target lithology), then some process has shallowed them over time. Since nearly all of Titan's recognized craters are located within the arid equatorial sand seas of organic-rich dunes, where rain is infrequent, and atmospheric sedimentation is expected to be low, it has been suggested that aeolian infill plays a major role in shallowing the craters. Topographic relaxation at Titan's current heat flow was previously assumed to be an unimportant process on Titan due to its low surface temperature (94 K). However, our estimate of the thermal conductivity of Titan's organic-rich sand is remarkably low (0.025 W m-1 K-1), and when in thick deposits, will result in a thermal blanketing effect that can aid relaxation. Here, we simulate the relaxation of Titan's craters Afekan, Soi, and Sinlap including thermal effects of various amounts of sand inside and around Titan's craters. We find that the combination of aeolian infill and subsequent relaxation can produce the current crater depths in a geologically reasonable period of time using Titan's current heat flow. Instead of needing to fill completely the missing volume with 100% sand, only ∼62%, ∼71%, and ∼97%, of the volume need be sand at the current basal heat flux for Afekan, Soi, and Sinlap, respectively. We conclude that both processes are likely at work shallowing these craters, and this finding contributes to why Titan overall lacks impact craters in the arid equatorial regions.

Crystal-field spectra of fassaite from the Angra dos Reis meteorite

Energy Technology Data Exchange (ETDEWEB)

Mao, H K; Bell, P M; Virgo, D [Carnegie Institution of Washington, D.C. (USA)

1977-06-01

Fassaitic pyroxene from the Angra dos Reis meteorite has striking spectral properties. The /sup 57/Fe Moessbauer spectra show no Fe/sup 3 +/, and thus the absorption is thought to originate from a complex charge-transfer process. Intense absorption at 480 nm dominates the spectrum of the meteorite and may be important in the interpretation of telescope spectra of objects in space.

Experimental investigation of crater growth dynamics

Science.gov (United States)

Schmidt, R. M.; Housen, K. R.; Bjorkman, M. D.; Holsapple, K. A.

1985-01-01

This work is a continuation of an ongoing program whose objective is to perform experiments and to develop scaling relationships for large-body impacts onto planetary surfaces. The centrifuge technique is used to provide experimental data for actual target materials of interest. With both power and gas guns mounted on the rotor arm, it is possible to match various dimensionless similarity parameters, which have been shown to govern the behavior of large-scale impacts. The development of the centrifuge technique has been poineered by the present investigators and is documented by numerous publications, the most recent of which are listed below. Understanding the dependence of crater size upon gravity has been shown to be key to the complete determination of the dynamic and kinematic behavior of crater formation as well as ejecta phenomena. Three unique time regimes in the formation of an impact crater have been identified.

Utilizing Weather RADAR for Rapid Location of Meteorite Falls and Space Debris Re-Entry

Science.gov (United States)

Fries, Marc D.

2016-01-01

This activity utilizes existing NOAA weather RADAR imagery to locate meteorite falls and space debris falls. The near-real-time availability and spatial accuracy of these data allow rapid recovery of material from both meteorite falls and space debris re-entry events. To date, at least 22 meteorite fall recoveries have benefitted from RADAR detection and fall modeling, and multiple debris re-entry events over the United States have been observed in unprecedented detail.

Anomalous Enantiomer Ratios in Meteoritic Sugar Derivatives

Science.gov (United States)

Cooper, G.; Sant, M.; Asiyo, C.

2009-03-01

The enantiomer (mirror-image) ratios of sugar acids in carbonaceous meteorites have been measured. D-enantiomer excesses are found in all acids measured thus far. This includes rare as well as common compounds.

Nature of Reduced Carbon in Martian Meteorites

Science.gov (United States)

Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.

2012-01-01

Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. Shergottites demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, Yamato 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures

Thermal and radiation history of meteorites as revealed by their thermoluminescence records

International Nuclear Information System (INIS)

Bhandari, N.

1985-01-01

Attempts are described to derive information about important parameters of the thermal and radiation history of meteorites from a study of depth profile of thermoluminescence coupled to appropriate annealing studies. In this review some possibilities are examined, emphasizing various factors cardinal to any meaningful application of TL in meteoritics. (author)

Measuring impact crater depth throughout the solar system

Science.gov (United States)

Robbins, Stuart J.; Watters, Wesley A.; Chappelow, John E.; Bray, Veronica J.; Daubar, Ingrid J.; Craddock, Robert A.; Beyer, Ross A.; Landis, Margaret E.; Ostrach, Lillian; Tornabene, Livio L.; Riggs, Jamie D.; Weaver, Brian P.

2018-01-01

One important, almost ubiquitous, tool for understanding the surfaces of solid bodies throughout the solar system is the study of impact craters. While measuring a distribution of crater diameters and locations is an important tool for a wide variety of studies, so too is measuring a crater's “depth.” Depth can inform numerous studies including the strength of a surface and modification rates in the local environment. There is, however, no standard data set, definition, or technique to perform this data‐gathering task, and the abundance of different definitions of “depth” and methods for estimating that quantity can lead to misunderstandings in and of the literature. In this review, we describe a wide variety of data sets and methods to analyze those data sets that have been, are currently, or could be used to derive different types of crater depth measurements. We also recommend certain nomenclature in doing so to help standardize practice in the field. We present a review section of all crater depths that have been published on different solar system bodies which shows how the field has evolved through time and how some common assumptions might not be wholly accurate. We conclude with several recommendations for researchers which could help different data sets to be more easily understood and compared.

AMMONIA IN THE EARLY SOLAR SYSTEM: AN ACCOUNT FROM CARBONACEOUS METEORITES

Energy Technology Data Exchange (ETDEWEB)

Pizzarello, S. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604 (United States); Williams, L. B., E-mail: pizzar@asu.edu [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States)

2012-04-20

This study presents a survey of abundance distribution and isotopic composition of the ammonia found incorporated in the kerogen-like insoluble material of selected carbonaceous chondrite meteorites; the ammonia was released upon hydrothermal treatment at 300 Degree-Sign C and 100 MPa. With the exception of Allende, a metamorphosed and highly altered stone, all the insoluble organic materials (IOM) of the meteorites analyzed released significant amounts of ammonia, which varied from over 4 {mu}g mg{sup -1} for the Orgueil IOM to 0.5 {mu}g mg{sup -1} for that of Tagish Lake; the IOM of the pristine Antarctica find GRA95229 remains the most rich in freeable ammonia with 10 {mu}g mg{sup -1}. While the amounts of IOM bound ammonia do not appear to vary between meteorites with a recognizable trend, a possible consequence of long terrestrial exposure of some of the stones, we found that the {delta}{sup 15}N composition of the ammonia-carrying materials is clearly distinctive of meteorite types and may reflect a preservation of the original {sup 15}N distribution of pre- and proto-solar materials.

Noachian and more recent phyllosilicates in impact craters on Mars.

Science.gov (United States)

Fairén, Alberto G; Chevrier, Vincent; Abramov, Oleg; Marzo, Giuseppe A; Gavin, Patricia; Davila, Alfonso F; Tornabene, Livio L; Bishop, Janice L; Roush, Ted L; Gross, Christoph; Kneissl, Thomas; Uceda, Esther R; Dohm, James M; Schulze-Makuch, Dirk; Rodríguez, J Alexis P; Amils, Ricardo; McKay, Christopher P

2010-07-06

Hundreds of impact craters on Mars contain diverse phyllosilicates, interpreted as excavation products of preexisting subsurface deposits following impact and crater formation. This has been used to argue that the conditions conducive to phyllosilicate synthesis, which require the presence of abundant and long-lasting liquid water, were only met early in the history of the planet, during the Noachian period (> 3.6 Gy ago), and that aqueous environments were widespread then. Here we test this hypothesis by examining the excavation process of hydrated minerals by impact events on Mars and analyzing the stability of phyllosilicates against the impact-induced thermal shock. To do so, we first compare the infrared spectra of thermally altered phyllosilicates with those of hydrated minerals known to occur in craters on Mars and then analyze the postshock temperatures reached during impact crater excavation. Our results show that phyllosilicates can resist the postshock temperatures almost everywhere in the crater, except under particular conditions in a central area in and near the point of impact. We conclude that most phyllosilicates detected inside impact craters on Mars are consistent with excavated preexisting sediments, supporting the hypothesis of a primeval and long-lasting global aqueous environment. When our analyses are applied to specific impact craters on Mars, we are able to identify both pre- and postimpact phyllosilicates, therefore extending the time of local phyllosilicate synthesis to post-Noachian times.

The Enantiomeric Ratios of Meteoritic Organic Compounds: Their Possible Roles in the Origin of Life

Science.gov (United States)

Cooper, George

2012-01-01

This talk will give an overview of the enantiomer (mirror-image) ratios of organic compounds in meteorites and also describe the results of the present work in my lab. The primary focus will be on sugar derivatives (sugar acids) of carbonaceous meteorites. Our work begins to address questions associated with chirality, i.e., the origins of homochirality. On Earth, biological monomers (amino acids, sugars, etc.) are usually found with one of the enantiomers more abundant than the other. However, biological polymers (proteins, nucleic acids, etc.) are only composed of one enantiomer i.e., they are homochiral. There are hints in meteorites that some organic molecules may also exist in homochiral forms. The talk will address questions such as: did extraterrestrial sources aid in the beginning of this homochirality? Do the increasing size and apparent enantiomer excesses of some meteoritic compounds also extend to larger meteoritic compounds and polymers?

Thermoluminescence studies of the thermal and radiation histories of chondritic meteorites

International Nuclear Information System (INIS)

Melcher, C.L.

1980-01-01

The thermoluminescence properties of chondritic meteorites are investigated to understand the ways in which the stored TL reflects the thermal and radiation histories of these objects. Differences in TL levels measured in recent falls are attributed to small differences in orbital temperatures. In addition, a correlation between TL level and terrestrial age is observed in meteorites of known terrestrial age. The thermoluminescence in chondrites is produced primarily by ionization from galactic cosmic rays with a much smaller contribution from the decay of natural radionuclides (U, Th, K, Rb). The production of most of the TL occurs after the break up of the large parent bodies into meter-size objects which are thus exposed to the ionizing effects of the cosmic rays. Measurements indicate that the low temperature TL represents a dynamic equilibrium between build up from ionizing radiation and thermal draining. The high temperature TL is near saturation. The terrestrial ages currently of greatest interest are those of the recently discovered meteorites in Antarctica. TL measurements were made on 11 of these meteorites and compared with the activities of 14 C, 26 Al, and 36 Cl measured by other workers in terrestrial age studies. A good correlation was found between the TL levels and the activities of cosmogenic radionuclides in these meteorites. Since the TL measurements can be made more rapidly and require much smaller samples (approx. 10 mg) than the radionuclide measurements, TL is most useful as a screening process to select potentially interesting samples for further study by more precise techniques

Molecular Asymmetry in Prebiotic Chemistry: An Account from Meteorites

Directory of Open Access Journals (Sweden)

Sandra Pizzarello

2016-04-01

Full Text Available Carbonaceous Chondrite (CC meteorites are fragments of asteroids, solar planetesimals that never became large enough to separate matter by their density, like terrestrial planets. CC contains various amounts of organic carbon and carry a record of chemical evolution as it came to be in the Solar System, at the time the Earth was formed and before the origins of life. We review this record as it pertains to the chiral asymmetry determined for several organic compounds in CC, which reaches a broad molecular distribution and enantiomeric excesses of up to 50%–60%. Because homochirality is an indispensable attribute of extant polymers and these meteoritic enantiomeric excesses are still, to date, the only case of chiral asymmetry in organic molecules measured outside the biosphere, the possibility of an exogenous delivery of primed prebiotic compounds to early Earth from meteorites is often proposed. Whether this exogenous delivery held a chiral advantage in molecular evolution remains an open question, as many others regarding the origins of life are.

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

Science.gov (United States)

Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

2013-01-01

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

Purple Salt and Tiny Drops of Water in Meteorites

Science.gov (United States)

Taylor, G. J.

1999-12-01

Some meteorites, especially those called carbonaceous chondrites, have been greatly affected by reaction with water on the asteroids in which they formed. These reactions, which took place during the first 10 million years of the Solar System's history, formed assorted water-bearing minerals, but nobody has found any of the water that caused the alteration. Nobody, that is, until now. Michael Zolensky and team of scientists from the Johnson Space Center in Houston and Virginia Tech (Blacksburg, Virginia) discovered strikingly purple sodium chloride (table salt) crystals in two meteorites. The salt contains tiny droplets of salt water (with some other elements dissolved in it). The salt is as old as the Solar System, so the water trapped inside the salt is also ancient. It might give us clues to the nature of the water that so pervasively altered carbonaceous chondrites and formed oceans on Europa and perhaps other icy satellites. However, how the salt got into the two meteorites and how it trapped the water remains a mystery - at least for now.

48Ca HETEROGENEITY IN DIFFERENTIATED METEORITES

International Nuclear Information System (INIS)

Chen, Hsin-Wei; Lee, Typhoon; Lee, Der-Chuen; Shen, Jason Jiun-San; Chen, Jiang-Chang

2011-01-01

Isotopic heterogeneities of 48 Ca have been found in numerous bulk meteorites that are correlated with 50 Ti and 54 Cr anomalies among differentiated planetary bodies, and the results suggest that a rare subset of neutron-rich Type Ia supernova (nSN Ia) was responsible for contributing these neutron-rich iron-group isotopes into the solar system (SS). The heterogeneity of these isotopes found in differentiated meteorites indicates that the isotopic compositions of the bulk SS are not uniform, and there are significant amounts of nSNe Ia dust incompletely mixed with the rest of SS materials during planetary formation. Combined with the data of now-extinct short-lived nuclide 60 Fe, which can be produced more efficiently from an nSN Ia than a Type II supernova ejecta, the observed planetary-scale isotopic heterogeneity probably reflects a late input of stellar dust grains with neutron-rich nuclear statistical equilibrium nuclides into the early SS.

Featured Image: Diamonds in a Meteorite

Science.gov (United States)

Kohler, Susanna

2018-04-01

This unique image which measures only 60 x 80 micrometers across reveals details in the Kapoeta meteorite, an 11-kg stone that fell in South Sudan in 1942. The sparkle in the image? A cluster of nanodiamonds discovered embedded in the stone in a recent study led by Yassir Abdu (University of Sharjah, United Arab Emirates). Abdu and collaborators showed that these nanodiamonds have similar spectral features to the interiors of dense interstellar clouds and they dont show any signs of shock features. This may suggest that the nanodiamonds were formed by condensation of nebular gases early in the history of the solar system. The diamonds were trapped in the surface material of the Kapoeta meteorites parent body, thought to be the asteroid Vesta. To read more about the authors study, check out the original article below.CitationYassir A. Abdu et al 2018 ApJL 856 L9. doi:10.3847/2041-8213/aab433

Martian Pyroxenes in the Shergottite Meteorites; Zagami, SAU005, DAG476 and EETA79001

Science.gov (United States)

Stephen, N.; Benedix, G. K.; Bland, P.; Hamilton, V. E.

2010-12-01

The geology and surface mineralogy of Mars is characterised using remote sensing techniques such as thermal emission spectroscopy (TES) from instruments on a number of spacecraft currently orbiting Mars or gathered from roving missions on the Martian surface. However, the study of Martian meteorites is also important in efforts to further understand the geological history of Mars or to interpret mission data as they are believed to be the only available samples that give us direct clues as to Martian igneous processes [1]. We have recently demonstrated that the spectra of Martian-specific minerals can be determined using micro-spectroscopy [2] and that these spectra can be reliably obtained from thin sections of Martian meteorites [3]. Accurate modal mineralogy of these meteorites is also important [4]. In this study we are using a variety of techniques to build upon previous studies of these particular samples in order to fully characterise the nature of the 2 common pyroxenes found in Martian Shergottites; pigeonite and augite [5], [6]. Previous studies have shown that the Shergottite meteorites are dominated by pyroxene (pigeonite and augite in varying quantities) [4], [5], commonly but not always olivine, plagioclase or maskelynite/glass and also hydrous minerals, which separate the Martian meteorites from other achondrites [7]. Our microprobe study of meteorites Zagami, EETA79001, SAU005 and DAG476 in thin-section at the Natural History Museum, London shows a chemical variability within both the pigeonite and augite composition across individual grains in all thin sections; variation within either Mg or Ca concentration varies from core to rim within the grains. This variation can also be seen in modal mineralogy maps using SEM-derived element maps and the Photoshop® technique previously described [4], and in new micro-spectroscopy data, particularly within the Zagami meteorite. New mineral spectra have been gathered from the Shergottite thin-sections by

Meteorites, atolls and whisky

Energy Technology Data Exchange (ETDEWEB)

NONE

1967-06-15

Improvements in the methods of measuring radioactive traces of elements in substances which can be hundreds of millions of years old have enabled many secrets of the remote past to be revealed. The techniques developed by nuclear scientists can also be applied to more recent times. In a symposium held in Monaco during March the discussions of radioactive dating and methods of low level counting brought references to meteorites, rocks, archaeology, coral atolls, ancient ceramics, and even whisky

Physics of soft impact and cratering

CERN Document Server

Katsuragi, Hiroaki

2016-01-01

This book focuses on the impact dynamics and cratering of soft matter to describe its importance, difficulty, and wide applicability to planetary-related problems. A comprehensive introduction to the dimensional analysis and constitutive laws that are necessary to discuss impact mechanics and cratering is first provided. Then, particular coverage is given to the impact of granular matter, which is one of the most crucial constituents for geophysics. While granular matter shows both solid-like and fluid-like behaviors, neither solid nor fluid dynamics is sufficient to fully understand the physics of granular matter. In order to reveal its fundamental properties, extensive impact tests have been carried out recently. The author reveals the findings of these recent studies as well as what remains unsolved in terms of impact dynamics. Impact crater morphology with various soft matter impacts also is discussed intensively. Various experimental and observational results up to the recent Itokawa asteroid’s terrain...

Crater monitoring through social media observations

Science.gov (United States)

Gialampoukidis, I.; Vrochidis, S.; Kompatsiaris, I.

2017-09-01

We have collected more than one lunar image per two days from social media observations. Each one of the collected images has been clustered into two main groups of lunar images and an additional cluster is provided (noise) with pictures that have not been assigned to any cluster. The proposed lunar image clustering process provides two classes of lunar pictures, at different zoom levels; the first showing a clear view of craters grouped into one cluster and the second demonstrating a complete view of the Moon at various phases that are correlated with the crawling date. The clustering stage is unsupervised, so new topics can be detected on-the-fly. We have provided additional sources of planetary images using crowdsourcing information, which is associated with metadata such as time, text, location, links to other users and other related posts. This content has crater information that can be fused with other planetary data to enhance crater monitoring.

On the history of the early meteoritic bombardment of the Moon: Was there a terminal lunar cataclysm?

Science.gov (United States)

Michael, Greg; Basilevsky, Alexander; Neukum, Gerhard

2018-03-01

This work revisits the hypothesis of the so-called 'lunar terminal cataclysm' suggested by Tera et al. (1973, 1974) as a strong peak in the meteorite bombardment of the Moon around 3.9 Ga ago. According to the hypothesis, most of the impact craters observed on the lunar highlands formed during this short time period and thus formed the majority of the lunar highland impact breccias and melts. The hypothesis arose from the observation that the ages of highland samples from all the lunar missions are mostly grouped around 3.9-4.0 Ga. Since those missions, however, radiometric dating techniques have progressed and many samples, both old and new, have been re-analyzed. Nevertheless, the debate over whether there was a terminal cataclysm persists. To progress in this problem we summarized results of 269 K-Ar datings (mostly made using the 40Ar-39Ar technique) of highland rocks represented by the Apollo 14, 15, 16, 17 and Luna 20 samples and 94 datings of clasts of the highland rocks from 23 lunar meteorites representing 21 localities on the lunar surface, and considered them jointly with the results of our modelling of the cumulative effect of the impact gardening process on the presence of impact melt of different ages at the near-surface of the Moon. The considered results of K-Ar dating of the Apollo-Luna samples of lunar highland rocks confirmed a presence of strong peak centered at 3.87 Ga. But since the time when the hypothesis of terminal cataclysm was suggested, it has become clear that this peak could be a result of sampling bias: it is the only prominent feature at the sites with an apparent domination of Imbrium basin ejecta (Apollo 14 and 15) and the age pattern is more complicated for the sites influenced not only by Imbrium ejecta but also that of other basins (Nectaris at the Apollo 16 site and Serenitatis at the Apollo 17 site). Our modelling shows that the cataclysm, if it occurred, should produce a strong peak in the measured age values but we see in

Planetary boundary layer and circulation dynamics at Gale Crater, Mars

Science.gov (United States)

Fonseca, Ricardo M.; Zorzano-Mier, María-Paz; Martín-Torres, Javier

2018-03-01

The Mars implementation of the Planet Weather Research and Forecasting (PlanetWRF) model, MarsWRF, is used here to simulate the atmospheric conditions at Gale Crater for different seasons during a period coincident with the Curiosity rover operations. The model is first evaluated with the existing single-point observations from the Rover Environmental Monitoring Station (REMS), and is then used to provide a larger scale interpretation of these unique measurements as well as to give complementary information where there are gaps in the measurements. The variability of the planetary boundary layer depth may be a driver of the changes in the local dust and trace gas content within the crater. Our results show that the average time when the PBL height is deeper than the crater rim increases and decreases with the same rate and pattern as Curiosity's observations of the line-of-sight of dust within the crater and that the season when maximal (minimal) mixing is produced is Ls 225°-315° (Ls 90°-110°). Thus the diurnal and seasonal variability of the PBL depth seems to be the driver of the changes in the local dust content within the crater. A comparison with the available methane measurements suggests that changes in the PBL depth may also be one of the factors that accounts for the observed variability, with the model results pointing towards a local source to the north of the MSL site. The interaction between regional and local flows at Gale Crater is also investigated assuming that the meridional wind, the dynamically important component of the horizontal wind at Gale, anomalies with respect to the daily mean can be approximated by a sinusoidal function as they typically oscillate between positive (south to north) and negative (north to south) values that correspond to upslope/downslope or downslope/upslope regimes along the crater rim and Mount Sharp slopes and the dichotomy boundary. The smallest magnitudes are found in the northern crater floor in a region that

Coordinated Chemical and Isotopic Imaging of Bells (CM2) Meteorite Matrix

Science.gov (United States)

Clemett, S. J.; Messenger, S.; Naklamura-Messenger, K.; Thomas-Keprta, K. L.

2014-01-01

Meteoritic organic matter is a complex conglomeration of species formed in distinct environments and processes in circumstellar space, the interstellar medium, the Solar Nebula and asteroids. Consequently meteorites constitute a unique record of primordial organic chemical evolution. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is little information as to how these species are spatially distributed and their relationship to the host mineral matrix. The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (chemical mapping study of the Bells meteorite using a newly developed two-step laser mass spectrometer (mu-L(sup 2)MS) capable of measuring a broad range of organic compounds.

Laboratory and Field Investigations of Small Crater Repair Technologies

National Research Council Canada - National Science Library

Priddy, Lucy P; Tingle, Jeb S; McCaffrey, Timothy J; Rollings, Ray S

2007-01-01

.... This airfield damage repair (ADR) investigation consisted of laboratory testing of selected crater fill and capping materials, as well as full-scale field testing of small crater repairs to evaluate field mixing methods, installation...

Chemical Structure of Insoluble Organic Matter of Meteorites

Science.gov (United States)

Derenne, S.; Robert, F.; Binet, L.; Gourier, D.; Rouzaud, J.-N.; Largeau, C.

A detailed knowledge of the insoluble organic matter (IOM) of the meteorites is essential to estimate to what extent the interstellar organic matter was preserved during the formation of the solar system and to decipher the synthetic pathways of this matter in space. Although predominant, the insoluble organic fraction has been much less extensively studied than soluble one due to specific analytical difficulties. The present work reports the examination of the IOM of two carbonaceous meteorites, Orgueil and Murchison through a number of various spectroscopic and microscopic methods, i. e. XANES for sulphur, carbon and nitrogen, solid state 13C NMR, electron paramagnetic resonance, electron nuclear double resonance and high resolution transmission electron microscopy.

Postshot distribution and movement of radionuclides in nuclear crater ejecta

Energy Technology Data Exchange (ETDEWEB)

Koranda, John J; Martin, John R; Wikkerink, Robert; Stuart, Marshall [Bio-Medical Division, Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1970-05-01

The distribution and postshot movement of radionuclides in nuclear crater ejecta are discussed in this report. Continuing studies of tritium movement in ejecta at SEDAN crater demonstrate that variations in tritium concentration are correlated with seasonal rainfall and soil water movements. Losses of 27 mCi H{sup 3}/ft{sup 2} are evident on SEDAN crater lip at the end of a three year period of measurements in -which an unusually large flux of rain was received. The distribution of gamma emitting radionuclides and tritium is described in the recently created SCHOONER crater ejecta field. The specific activity of radionuclides in the SCHOONER ejecta continuum is shown for ejecta collected from the crater lip to 17 miles from GZ. The movement of W{sup 181} and tritium into the sub-ejecta preshot soil is described at a site 3000 feet from GZ. (author)

Mass Movement on Vesta at Steep Scarps and Crater Rims

Science.gov (United States)

Krohn, K.; Jaumann, R.; Otto, K.; Hoogenboom, T.; Wagner, R.; Buczkowski, D. L.; Garry, B.; Williams, D. A.; Yingst, R. A.; Scully, J.;

Mass movement on Vesta at steep scarps and crater rims

Science.gov (United States)

Krohn, K.; Jaumann, R.; Otto, K.; Hoogenboom, T.; Wagner, R.; Buczkowski, D. L.; Garry, B.; Williams, D. A.; Yingst, R. A.; Scully, J.; De Sanctis, M. C.; Kneissl, T.; Schmedemann, N.; Kersten, E.; Stephan, K.; Matz, K.-D.; Pieters, C. M.; Preusker, F.; Roatsch, T.; Schenk, P.; Russell, C. T.; Raymond, C. A.

2014-12-01

The Quadrangles Av-11 and Av-12 on Vesta are located at the northern rim of the giant Rheasilvia south polar impact basin. The primary geologic units in Av-11 and Av-12 include material from the Rheasilvia impact basin formation, smooth material and different types of impact crater structures (such as bimodal craters, dark and bright crater ray material and dark ejecta material). Av-11 and Av-12 exhibit almost the full range of mass wasting features observed on Vesta, such as slump blocks, spur-and-gully morphologies and landslides within craters. Processes of collapse, slope instability and seismically triggered events force material to slump down crater walls or scarps and produce landslides or rotational slump blocks. The spur-and-gully morphology that is known to form on Mars is also observed on Vesta; however, on Vesta this morphology formed under dry conditions.

Enrichment of the Amino Acid L-Isovaline by Aqueous Alteration on CI and CM Meteorite Parent Bodies

Science.gov (United States)

Glavin, Daniel P.; Dworkin, Jason P.

2009-01-01

The distribution and enantiomeric composition of the 5-carbon (C(sub 5)) amino acids found in Cl-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with o-phthaldialdehyde/Nacetyl- l-cysteine derivatization. A large L-enantiomeric excess (ee) of the a-methyl amino acid isovaline was found in the CM meteorite Murchison (L(sub ee) = 18.5 +/- 2.6%) and the Cl meteorite Orguell (L(sub ee) = 15.2 +/- 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any Cl meteorite. The L-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C(sub 5) amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no L-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for L-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other alpha-dialkyl amino acids found in altered Ct and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.

Weldability of an iron meteorite by Friction Stir Spot Welding: A contribution to in-space manufacturing

Science.gov (United States)

Evans, William Todd; Neely, Kelsay E.; Strauss, Alvin M.; Cook, George E.

2017-11-01

Friction Stir Welding has been proposed as an efficient and appropriate method for in space welding. It has the potential to serve as a viable option for assembling large scale space structures. These large structures will require the use of natural in space materials such as those available from iron meteorites. Impurities present in most iron meteorites limit its ability to be welded by other space welding techniques such as electron beam laser welding. This study investigates the ability to weld pieces of in situ Campo del Cielo meteorites by Friction Stir Spot Welding. Due to the rarity of the material, low carbon steel was used as a model material to determine welding parameters. Welded samples of low carbon steel, invar, and Campo del Cielo meteorite were compared and found to behave in similar ways. This study shows that meteorites can be Friction Stir Spot Welded and that they exhibit properties analogous to that of FSSW low carbon steel welds. Thus, iron meteorites can be regarded as another viable option for in-space or Martian construction.

Crater Highlands, Tanzania

Science.gov (United States)

2006-01-01

The Shuttle Radar Topography Mission (SRTM), flown aboard Space Shuttle Endeavour in February 2000, acquired elevation measurements for nearly all of Earth's landmass between 60oN and 56oS latitudes. For many areas of the world SRTM data provide the first detailed three-dimensional observation of landforms at regional scales. SRTM data were used to generate this view of the Crater Highlands along the East African Rift in Tanzania. Landforms are depicted with colored height and shaded relief, using a vertical exaggeration of 2X and a southwestwardly look direction. Lake Eyasi is depicted in blue at the top of the image, and a smaller lake occurs in Ngorongoro Crater. Near the image center, elevations peak at 3648 meters (11,968 feet) at Mount Loolmalasin, which is south of Ela Naibori Crater. Kitumbeine (left) and Gelai (right) are the two broad mountains rising from the rift lowlands. Mount Longido is seen in the lower left, and the Meto Hills are in the right foreground. Tectonics, volcanism, landslides, erosion and deposition -- and their interactions -- are all very evident in this view. The East African Rift is a zone of spreading between the African (on the west) and Somali (on the east) crustal plates. Two branches of the rift intersect here in Tanzania, resulting in distinctive and prominent landforms. One branch trends nearly parallel the view and includes Lake Eyasi and the very wide Ngorongoro Crater. The other branch is well defined by the lowlands that trend left-right across the image (below center, in green). Volcanoes are often associated with spreading zones where magma, rising to fill the gaps, reaches the surface and builds cones. Craters form if a volcano explodes or collapses. Later spreading can fracture the volcanoes, which is especially evident on Kitumbeine and Gelai Mountains (left and right, respectively, lower center). The Crater Highlands rise far above the adjacent savannas, capture moisture from passing air masses, and host rain

Indigenous Carbonaceous Matter in the Nakhla Mars Meteorite

Science.gov (United States)

Clemett, S. J.; Thomas-Keprta, K. L.; Rahman, Z.; Le, L.; Wentworth, S. J.; Gibson, E. K.; McKay, D. S.

2016-01-01

Detailed microanalysis of the Martian meteorite Nakhla has shown there are morphologically distinct carbonaceous features spatially associated with low-T aqueous alteration phases including salts and id-dingsite. A comprehensive suite of analytical instrumentation including optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), two-step laser mass spectrometry (mu-L(sup 2)MS), laser mu-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nanoscale secondary ion mass spectrometry (NanoSIMS) are being used to characterize the carbonaceous matter and host mineralogy. The search for carbonaceous matter on Mars has proved challenging. Viking Landers failed to unambiguously detect simple organics at either of the two landing sites although the Martian surface is estimated to have acquired at least 10(exp15) kg of C as a consequence of meteoritic accretion over the last several Ga. The dearth of organics at the Martian surface has been attributed to various oxidative processes including UV photolysis and peroxide activity. Consequently, investigations of Martian organics need to be focused on the sub-surface regolith where such surface processes are either severely attenuated or absent. Fortuitously since Martian meteorites are derived from buried regolith materials they provide a unique opportunity to study Martian organic geochemistry.

Annama H5 meteorite fall: orbit, trajectory, recovery, petrology, noble gases and cosmogenic radionuclides

Czech Academy of Sciences Publication Activity Database

Kohout, Tomáš; Gritsevich, M.; Lyytinen, E.; Moilanen, J.

2015-01-01

Roč. 50, Supplement 1 SI (2015) [Annual Meeting of the Meteoritical Society /78./. 27.07.2015-31.07.2015, Berkeley] Institutional support: RVO:67985831 Keywords : meteorite * astrophysics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Geology and mineralogy of the Auki Crater, Tyrrhena Terra, Mars: A possible post impact-induced hydrothermal system

Science.gov (United States)

Carrozzo, F. G.; Di Achille, G.; Salese, F.; Altieri, F.; Bellucci, G.

2017-01-01

A variety of hydrothermal environments have been documented in terrestrial impact structures. Due to both past water interactions and meteoritic bombardment on the surface of Mars, several authors have predicted various scenarios that include the formation of hydrothermal systems. Geological and mineralogical evidence of past hydrothermal activity have only recently been found on Mars. Here, we present a geological and mineralogical study of the Auki Crater using the spectral and visible imagery data acquired by the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars), CTX (Context Camera) and HiRISE (High Resolution Imaging Science Experiment) instruments on board the NASA MRO mission. The Auki Crater is a complex crater that is ∼38 km in diameter located in Tyrrhena Terra (96.8°E and 15.7°S) and shows a correlation between its mineralogy and morphology. The presence of minerals, such as smectite, silica, zeolite, serpentine, carbonate and chlorite, associated with morphological structures, such as mounds, polygonal terrains, fractures and veins, suggests that the Auki Crater may have hosted a post impact-induced hydrothermal system. Although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate-rich bedrock units as a consequence of crater formation, we favor the hypothesis of impact-induced hydrothermal circulation within fractures and subsequent mineral deposition. The hydrothermal system could have been active for a relatively long period of time after the impact, thus producing a potential transient habitable environment. It must be a spectrally neutral component to emphasize the spectral features; It is an average of spectra taken in the same column of the numerator spectra to correct the residual instrument artifacts and reduce detector noise that changes from column to column; It must be taken in

Observational constraints on the identification of shallow lunar magmatism : insights from floor-fractured craters

OpenAIRE

Jozwiak, Lauren; Head, James; Neumann, G. A.; Wilson, Lionel

2017-01-01

Floor-fractured craters are a class of lunar crater hypothesized to form in response to the emplacement of a shallow magmatic intrusion beneath the crater floor. The emplacement of a shallow magmatic body should result in a positive Bouguer anomaly relative to unaltered complex craters, a signal which is observed for the average Bouguer anomaly interior to the crater walls. We observe the Bouguer anomaly of floor-fractured craters on an individual basis using the unfiltered Bouguer gravity so...

Carbon Isotope Analyses of Individual Hydrocarbon Molecules in Bituminous Coal, Oil Shale and Murchison Meteorite

Directory of Open Access Journals (Sweden)

Kyoungsook Kim

1998-06-01

Full Text Available To study the origin of organic matter in meteorite, terrestrial rocks which contain organic compounds similar to the ones found in carbonaceous chondrites are studied and compared with Murchison meteorite. Hydrocarbon molecules were extracted by benzene and methanol from bituminous coal and oil shale and the extracts were partitioned into aliphatic, aromatic, and polar fractions by silica gel column chromatography. Carbon isotopic ratios in each fractions were analysed by GC-C-IRMS. Molecular compound identifications were carried by GC-MS Engine. Bituminous coal and oil shale show the organic compound composition similar to that of meteorite. Oil shale has a wide range of δ(13C, -20.1%_0 - -54.4%_0 compared to bituminous coal, -25.2%_0 - -34.3%_0. Delta values of several molecular compounds in two terrestrial samples are different. They show several distinct distributions in isotopic ratios compared to those of meteorite; Murchison meteorite has a range of δ(13C from -13%_0 to +30%_0. These results provide interpretation for the source and the formation condition of each rock, in particular alteration and migration processes of organic matter. Especially, they show an important clue whether some hydrocarbon molecules observed in meteorite are indigenous or not.

The New Peruvian Meteorite Carancas: Mössbauer Spectroscopy and X-Ray Diffraction Studies

Science.gov (United States)

Munayco, P.; Munayco, J.; Varela, M. E.; Scorzelli, R. B.

2013-02-01

The Carancas meteorite fell on 15 September 2007 approximately 10 km south of Desaguadero, near Lake Titicaca, Peru, producing bright lights, clouds of dust in the sky and intense detonations. The Carancas meteorite is classified as a H4-5 ordinary chondrite with shock stage S3 and a degree of weathering W0. The Carancas meteorite is characterized by well defined chondrules composed either of olivine or pyroxene. The Mössbauer spectra show an overlapping of paramagnetic and magnetic phases. The spectra show two quadrupole doublets associated to olivine and pyroxene; and two magnetic sextets, associated with the primary phases kamacite/taenite and Troilite (Fe2+). Metal particles were extracted from the bulk powdered samples exhibit only kamacite and small amounts of the intergrowth tetrataenite/antitaenite. X-Ray diffractogram shows the primary phases olivine, pyroxene, troilite, kamacite, diopside and albite. Iron oxides has not been detected by Mössbauer spectroscopy or XRD as can be expected for a meteorite immediately recovered after its fall.

Mineralized remains of morphotypes of filamentous cyanobacteria in carbonaceous meteorites

Science.gov (United States)

Hoover, Richard B.

2005-09-01

The quest for conclusive evidence of microfossils in meteorites has been elusive. Abiotic microstructures, mineral grains, and even coating artifacts may mimic unicellular bacteria, archaea and nanobacteria with simple spherical or rod morphologies (i.e., cocci, diplococci, bacilli, etc.). This is not the case for the larger and more complex microorganisms, colonies and microbial consortia and ecosystems. Microfossils of algae, cyanobacteria, and cyanobacterial and microbial mats have been recognized and described from many of the most ancient rocks on Earth. The filamentous cyanobacteria and sulphur-bacteria have very distinctive size ranges, complex and recognizable morphologies and visibly differentiated cellular microstructures. The taphonomic modes of fossilization and the life habits and processes of these microorganisms often result in distinctive chemical biosignatures associated with carbonization, silicification, calcification, phosphatization and metal-binding properties of their cell-walls, trichomes, sheaths and extracellular polymeric substances (EPS). Valid biogenicity is provided by the combination of a suite of known biogenic elements (that differ from the meteorite matrix) found in direct association with recognizable and distinct biological features and microstructures (e.g., uniseriate or multiseriate filaments, trichomes, sheaths and cells of proper size/size range); specialized cells (e.g., basal or apical cells, hormogonia, akinetes, and heterocysts); and evidence of growth characteristics (e.g., spiral filaments, robust or thin sheaths, laminated sheaths, true or false branching of trichomes, tapered or uniform filaments) and evidence of locomotion (e.g. emergent cells and trichomes, coiling hormogonia, and hollow or flattened and twisted sheaths). Since 1997 we have conducted Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) studies of freshly fractured interior surfaces of carbonaceous meteorites, terrestrial

Determination of refractory trace elements in Chinese meteorites by RNAA

International Nuclear Information System (INIS)

Kraehenbuehl, U.; Burger, M.

1989-01-01

Some refractory trace elements are important target elements for spallation reactions in meteorites. These elements also serve to characterize the investigated meteorites. The elements Ti, Y, Zr, Hf, W and Ta were measured after radiochemical separation in chondrites from China. After acid digestion of the irradiated samples, the group separations were obtained by precipitation reactions. The necessary radiochemical purification of the pure β emitter Y was realized on a Lewatite OC 1026 column. For all the other elements discrete gamma radiation was measured. (orig.)

Forging Asteroid-Meteorite Relationships Through Reflectance Spectroscopy

Science.gov (United States)

Burbine, T. H.; Binzel, R. P.; Bus, S. J.; Buchanan, P. C.; Hinrichs, J. L.; Meibom, A.; Hiroi, T.; Sunshine, J. M.

2000-01-01

Near-infrared spectra were obtained for 196 asteroids as part of SMASSIR. SMASSIR focused on observing asteroids assumed to be one of the following: (1) olivine-rich, (2) objects with "Vesta-like spectra" (the "Vestoids"), and (3) postulated meteorite parent bodies.

Crater Lake Controls on Volcano Stability: Insights From White Island, New Zealand

Science.gov (United States)

Hamling, Ian J.

2017-11-01

Many volcanoes around the world host summit crater lakes but their influence on the overall stability of the edifice remains poorly understood. Here I use satellite radar data acquired by TerraSAR-X from early 2015 to July 2017 over White Island, New Zealand, to investigate the interaction of the crater lake and deformation of the surrounding edifice. An eruption in April 2016 was preceded by a period of uplift within the crater floor and drop in the lake level. Modeling of the uplift indicates a shallow source located at ˜100 m depth in the vicinity of the crater lake, likely coinciding with the shallow hydrothermal system. In addition to the drop in the lake level, stress changes induced by the inflation suggest that the pressurization of the shallow hydrothermal system helped promote failure along the edge of the crater lake which collapsed during the eruption. After the eruption, and almost complete removal of the crater lake, large areas of the crater wall and lake edge began moving downslope at rates approaching 400 mm/yr. The coincidence between the rapid increase in the displacement rates and removal of the crater lake suggests that the lake provides a physical control on the stability of the surrounding edifice.

Role of impact cratering for Mars sample return

International Nuclear Information System (INIS)

Schultz, P.H.

1988-01-01

The preserved cratering record of Mars indicates that impacts play an important role in deciphering Martian geologic history, whether as a mechanism to modify the lithosphere and atmosphere or as a tool to sample the planet. The various roles of impact cratering in adding a broader understanding of Mars through returned samples are examined. Five broad roles include impact craters as: (1) a process in response to a different planetary localizer environment; (2) a probe for excavating crustal/mantle materials; (3) a possible localizer of magmatic and hydrothermal processes; (4) a chronicle of changes in the volcanic, sedimentary, atmospheric, and cosmic flux history; and (5) a chronometer for extending the geologic time scale to unsampled regions. The evidence for Earth-like processes and very nonlunar styles of volcanism and tectonism may shift the emphasis of a sampling strategy away from equally fundamental issues including crustal composition, unit ages, and climate history. Impact cratering not only played an important active role in the early Martian geologic history, it also provides an important tool for addressing such issues

Are There High Meteorite Concentrations in the Atacama Desert/Chile?

Science.gov (United States)

Scherer, P.; Delisle, G.

1992-07-01

We have visited numerous regions of the Atacama desert between Copiapo (27 degrees, 15'S) and Calama (22 degrees, 25'S) to assess their potential as a high-yield meteorite concentration surface, easily exploitable by search efforts within a reasonable time frame. According to our observations, this desert is characterized by the following features: a) A high percentage of the desert consists of sloping surfaces on which soil movement occurs, presumably by very infrequent, though heavy rain. b) Vast areas of the desert are covered by a dm-thick sand layer of dark colour. Since the sand is too coarse-grained to be transported by wind it presumably resulted from in-situ weathering of rock debris derived from nearby mountains. We suspect that impacting smaller objects can easily penetrate the sand layer. c) The sand layer is typically dotted by rocks, fist-size or smaller, that are covered by a thick layer of desert paint (reddish-brown to black colour). Most country rocks are of volcanic origin (rhyolite, andesite, basalt) and are typically of grey to black colour. A noticeable colour contrast in particular to potential stony meteorites is almost nonexistent. d) Soil salts with a potential to speed up weathering processes are ubiquitous near the surface. e) The Pampa de Mejillones, 45 km north of Antofagasta, is one of the few light-coloured areas in the Atacama desert. The surface, being of Mio-Pliocene age, consists of an almost continuous layer of light-brown fossil shells (bivalves and gastropodes). Fluvially transported dark rocks from adjacent outcrops rest on top. The latter material is covered again by desert paint. Few meteorite discoveries have been reported from this area (Pampa (a),(b),(c)). f) Numerous old tire tracks, in particular around mines in operation, crisscross most areas of the Atacama. Undetected objects such as large masses of iron bodies are not likely to have remained undiscovered in great numbers any more. We conclude that the potential of

Bacteria in the Tatahouine meteorite: nanometric-scale life in rocks.

Science.gov (United States)

Gillet, P h; Barrat, J A; Heulin, T h; Achouak, W; Lesourd, M; Guyot, F; Benzerara, K

2000-02-15

We present a study of the textural signature of terrestrial weathering and related biological activity in the Tatahouine meteorite. Scanning and transmission electron microscopy images obtained on the weathered samples of the Tatahouine meteorite and surrounding soil show two types of bacteria-like forms lying on mineral surfaces: (1) rod-shaped forms (RSF) about 70-80 nm wide and ranging from 100 nm to 600 nm in length; (2) ovoid forms (OVF) with diameters between 70 and 300 nm. They look like single cells surrounded by a cell wall. Only Na, K, C, O and N with traces of P and S are observed in the bulk of these objects. The chemical analyses and electron diffraction patterns confirm that the RSF and OVF cannot be magnetite or other iron oxides, iron hydroxides, silicates or carbonates. The sizes of the RSF and OVF are below those commonly observed for bacteria but are very similar to some bacteria-like forms described in the Martian meteorite ALH84001. All the previous observations strongly suggest that they are bacteria or their remnants. This conclusion is further supported by microbiological experiments in which pleomorphic bacteria with morphology similar to the OVF and RSF objects are obtained from biological culture of the soil surrounding the meteorite pieces. The present results show that bacteriomorphs of diameter less than 100 nm may in fact represent real bacteria or their remnants.

Nucleation of the Widmanstatten Pattern in Iron Meteorites

Science.gov (United States)

Yang, J.; Goldstein, J. I.

2004-01-01

The Widmanstatten pattern develops at low temperatures during the evolution of the asteroids. We have studied the origin of the Widmanstatten pattern in order to obtain metallographic cooling rates in the temperature range (approx. 700 to 300 deg C). This paper summarizes our recent evaluation of the various mechanisms for the formation of the Widmanstatten pattern. All chemical groups of the iron meteorites are considered. We also propose a new mechanism for the formation of the Widmanstatten pattern in the low P metal phase of iron, stony-iron and stony meteorites. The results of this evaluation enables us to more accurately determine metallographic cooling rates particularly when incorporated with other recent advances in Fe-Ni and Fe-Ni (P saturated) phase diagrams and interdiffusion coefficients.

France

International Nuclear Information System (INIS)

Hourcade, J.C.

1990-01-01

The French energy system, like that of most energy-importing nations, was profoundly transformed by the first oil shock. But France was more vulnerable than any other industrialized country besides Japan to oil supply disruption: in 1973, the nation imported 77 percent of total primary energy requirements of 7.6 EJ, and 98 percent of its petroleum. Two imperatives have since formed the 'French response' to the threat of external energy supply disruptions: augmentation of the rate of energy self-sufficiency, and minimization of major macroeconomic dislocations. These two objectives displaced a high priority in France in the early 1970s - protection of the natural environment. Because France has embraced nuclear power, it is often viewed by its European neighbors as having feeble ecological sensibility. At that time, France had a rather advanced policy in this field: sulfur emissions laws were enacted in 1967 and a Ministry of Environment was created in January 1971. Now that environmental concerns have re-emerged as an important force, France finds itself with a plausible greenhouse response in a mix of policies - without environmental protection having been the objective envisioned

Site characterization requirements for nuclear-cratering design

International Nuclear Information System (INIS)

Terhune, R.W.; Carlson, R.C.

1977-01-01

A material properties measurement program for the design of large engineering nuclear-excavation projects by computer calculation is presented. Material properties of the site and their relative effect on crater size are analyzed and ordered in relation to their importance in determining the overall cratering efficiency. The measurement program includes both in situ logging and laboratory measurement of core samples, together with the reason for each measurement and its use in the calculations

Crater Morphometry and Crater Degradation on Mercury: Mercury Laser Altimeter (MLA) Measurements and Comparison to Stereo-DTM Derived Results

Science.gov (United States)

Leight, C.; Fassett, C. I.; Crowley, M. C.; Dyar, M. D.

2017-01-01

Two types of measurements of Mercury's surface topography were obtained by the MESSENGER (MErcury Surface Space ENvironment, GEochemisty and Ranging) spacecraft: laser ranging data from Mercury Laser Altimeter (MLA) [1], and stereo imagery from the Mercury Dual Imaging System (MDIS) camera [e.g., 2, 3]. MLA data provide precise and accurate elevation meaurements, but with sparse spatial sampling except at the highest northern latitudes. Digital terrain models (DTMs) from MDIS have superior resolution but with less vertical accuracy, limited approximately to the pixel resolution of the original images (in the case of [3], 15-75 m). Last year [4], we reported topographic measurements of craters in the D=2.5 to 5 km diameter range from stereo images and suggested that craters on Mercury degrade more quickly than on the Moon (by a factor of up to approximately 10×). However, we listed several alternative explanations for this finding, including the hypothesis that the lower depth/diameter ratios we observe might be a result of the resolution and accuracy of the stereo DTMs. Thus, additional measurements were undertaken using MLA data to examine the morphometry of craters in this diameter range and assess whether the faster crater degradation rates proposed to occur on Mercury is robust.

Review of the Sayh al Uhaymir (SaU 005, Plus Pairings, Martian Meteorite from Al Wusta, Oman

Directory of Open Access Journals (Sweden)

Arshad Ali

2017-01-01

Full Text Available Al Wusta is a desert area in the Sultanate of Oman which is famous due to the discovery of a number of Martian and Lunar meteorites since the start of the present millennium. According to the Meteoritical Bulletin database, 137 approved Martian meteorites have been found worldwide, including 17 from Oman (4 from Zufar, 13 from Al Wusta region. Interestingly 11 finds in the last 15 years have been of Sayh al Uhaymir (SaU 005 and its pairings. These finds (estimated mass = 11.2 kg are linked to 10 search expeditions carried out between November 26, 1999 and March 2, 2014 by the Swiss group from the University of Bern and several anonymous meteorite hunters. The bulk of these meteorites (~97% is in the possession of anonymous collectors, negatively affecting Oman’s natural heritage and denying further research opportunities, given their associated scientific value. SaU 005 and its pairings belong to the shergottite group of the Shergotty-Nakhla-Chassigny (SNC meteorites, originating from various depths within the Martian mantle. We discuss the recently published oxygen isotope data of bulk and mineral fractions of SaU 008 recovered during the very first expedition in 1999 in the context of other shergottites found in Oman. The bulk oxygen isotope data of SaU 008 and Dhofar 019, another Martian meteorite from Oman, show a narrow range in δ18O values. Their Δ17O values are remarkably close to identical and fall linearly on a Martian fractionation line above the terrestrial fractionation line (TFL by + 0.32‰, suggesting that Mars’ mantle is homogeneous in oxygen isotopes. Petrographic and mineralogical data of SaU 005 and other pairings published in the Meteoritical Bulletin are compiled, and it is noted that all the meteorites are identical and are likely paired. The story behind these rare extra-terrestrial specimens demands a local meteorite museum and preliminary testing laboratory at Sultan Qaboos University (SQU to protect this treasure

Presolar Diamond in Meteorites

OpenAIRE

Amari, Sachiko

2009-01-01

Presolar diamond, the carrier of the isotopically anomalous Xe component Xe-HL, was the first mineral type of presolar dust that was isolated from meteorites. The excesses in the light, p-process only isotopes 124Xe and 126Xe, and in the heavy, r-process only isotopes 134Xe and 136Xe relative to the solar ratios indicate that Xe-HL was produced in supernovae: they are the only stellar source where these two processes are believed to take place. Although these processes occur in supernovae, th...

Floor-fractured craters on the Moon: an evidence of past intrusive magmatic activity

Science.gov (United States)

Thorey, C.; Michaut, C.

2012-12-01

Floor-fractured lunar craters (FFC's) are a class of craters modified by post impact mechanisms. They are defined by distinctive shallow, often plate-like or convex floors, wide floor moats and radial, concentric and polygonal floor-fractures, suggesting an endogenous process of modification. Two main mechanisms have been proposed to account for such observations : 1) viscous relaxation and 2) spreading of magmatic intrusions at depth below the crater. Here, we propose to test the case of magmatic intrusions. We develop a model for the dynamics of magma spreading below an elastic crust with a crater-like topography and above a rigid horizontal surface. Results show first that the lithostatic pressure increase at the crater rim prevents the intrusion from spreading horizontally giving rise to intrusion thickening and to an uplift of the crater floor. Second, the deformation of the overlying crust exerts a strong control on the intrusion shape, and hence, on the nature of the crater floor uplift. As the deformation can only occur over a minimum flexural wavelength noted Λ, the intrusion shape shows a bell-shaped geometry for crater radius smaller than 3Λ, or a flat top with smooth edges for crater radius larger than 3Λ. For given crustal elastic properties, the crust flexural wavelength increases with the intrusion depth. Therefore, for a large intrusion depth or small crater size, we observe a convex uplift of the crater floor. On the contrary, for a small intrusion depth or large crater size, the crater floor undergoes a piston-like uplift and a circular moat forms just before the rim. The depth of the moat is controlled by the thickening of the crust at the crater rim. On the contrary to viscous relaxation models, our model is thus able to reproduce most of the features of FFC's, including small-scale features. Spreading of a magmatic intrusion at depth can thus be considered as the main endogenous mechanism at the origin of the deformations observed at FFC

East Part of Sapas Mons with Flooded Crater

Science.gov (United States)

1991-01-01

This Magellan image centered near 9.6 degrees north latitude, 189.5 degrees east longitude of an area 140 kilometers (87 miles) by 110 kilometers (68 miles) covers part of the eastern flank of the volcano Sapas Mons on the western edge of Atla Regio. The bright lobate features along the southern and the western part of the image, oriented in northeast to southwest directions, are lava flows that are rough at the 12.6 centimeter wavelength of the radar. These flows range in width from 5 kilometers to 25 kilometers (3 to 16 miles) with lengths of 50 kilometers to 100 kilometers (31 to 62 miles), extending off the area shown here. Additional radar-dark (smooth) flows are also present. The radar-bright linear structures in the northwest part of the image are interpreted to be faults and fractures possibly associated with the emplacement of magma in the subsurface. Located near the center of the image is a 20 kilometer (12 mile) diameter impact crater. This crater is superimposed on a northeast/southwest trending fracture while the southern part of the crater's ejecta blanket is covered by a 6 kilometer (4 mile) wide radar-bright lava flow. These relations indicate that the crater post dates an episode of fracturing and is older than the lava flows covering its southern edge. This is one of only a few places on Venus in which an impact crater is seen to be covered by volcanic deposits.

Meteorite Dichotomy Implies that Jupiter Formed Early

Science.gov (United States)

Kruijer, T. S.; Burkhardt, C.; Budde, G.; Kleine, T.

2018-05-01

Meteorites derive from two distinct nebular reservoirs that co-existed and remained spatially separated between 1 and 3–4 Ma after CAIs. This can most easily be explained if Jupiter acted as a barrier and formed early, within less than 1 Ma.

Floor-Fractured Craters on Ceres and Implications for Internal Composition and Processes

Science.gov (United States)

Buczkowski, D.; Schenk, P.; Scully, J. E. C.; Park, R. S.; Preusker, F.; Raymond, C. A.; Russell, C. T.

2016-12-01

Several of the impact craters on Ceres have patterns of fractures on their floors. These fractures appear similar to those found within a class of lunar craters referred to as Floor-Fractured Craters (FFCs) [1]. Lunar FFCs are characterized by anomalously shallow floors cut by radial, concentric, and/or polygonal fractures, and have been classified into crater classes, Types 1 through 6, based on their morphometric properties [1,2]. Models for their formation have included both floor uplift due to magmatic intrusion below the crater or floor shallowing due to viscous relaxation. However, the observation that the depth versus diameter (d/D) relationship of the FFCs is distinctly shallower than the same association for other lunar craters supports the hypotheses that the floor fractures form due to shallow magmatic intrusion under the crater [2]. We have cataloged the Ceres FFCs according to the classification scheme designed for the Moon. Large (>50 km) Ceres FFCs are most consistent with Type 1 lunar FFCs, having deep floors, central peaks, wall terraces, and radial and/or concentric fractures. Smaller craters on Ceres are more consistent with Type 4 lunar FFCs, having less-pronounced floor fractures and v-shaped moats separating the wall scarp from the crater interior. An analysis of the d/D ratio for Ceres craters shows that, like lunar FFCs, the Ceres FFCs are anomalously shallow. This suggests that the fractures on the floor of Ceres FFCs may be due the intrusion of a low-density material below the craters that is uplifting their floors. While on the Moon the intrusive material is hypothesized to be silicate magma, this is unlikely for Ceres. However, a cryovolcanic extrusive edifice has been identified on Ceres [3], suggesting that cryomagmatic intrusions could be responsible for the formation of the Ceres FFCs. References: [1] Schultz P. (1976) Moon, 15, 241-273 [2] Jozwiak L.M. et al (2015) JGR 117, doi: 10.1029/2012JE004134 [3] Ruesch O. et al (2016

Chladniite: A New Mineral Honoring the Father of Meteoritics

Science.gov (United States)

McCoy, T. J.; Steele, I. M.; Keil, K.; Leonard, B. F.; Endress, M.

1993-07-01

The IIICD irons are a small group of meteorites, three of which (Maltahohe, Carlton, and Dayton) contain silicate-bearing inclusions rich in troilite, graphite, schreibersite, and phosphates [1]. The Na,Ca,Mg-rich phosphates bnanite and panethite were first described in Dayton [2]. We have discovered a new mineral, Na(sub)2CaMg(sub)7(PO(sub)4)(sub)6, as a single grain within a silicate-bearing inclusion in the Carlton (IIICD) iron meteorite. The mineral and mineral name have been approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association. Chladniite occurs as a single grain near the edge of a silicate-bearing inclusion in polished section USNM 2707. This inclusion is dominated by chlorapatite and contains olivine, pyroxene, plagioclase, schreibersite, and troilite. Chladniite occurs as a single, massive grain (975 x 175 micrometers) and is cross-cut by hydrated iron oxides of terrestrial origin. In polished section, it is gray, dark, and weakly anisotropic. Cleavage is rhomboidal in plan and very likely rhombohedral in three dimension. The formula for chladniite (derived from five microprobe analyses) is Na(sub)1.77Si(sub)0.08 Ca(sub)0.98(Mg(sub)6.96Fe(sub)0.26Mn(sub)0.04)(sub)Sigma = 7.26(Po(sub)0.98 O(sub)4)(sub)6. The idealized formula is Na(sub)2CaMg(sub)7(PO(sub)4)(sub)6. Chladniite is related to two rare minerals, fillowite [3] and johnsomervilleite [4], where fillowite is the Mn-dominated and johnsomervilleite the Fe-dominated analog of chladniite. The unique occurrence of chladniite, the relatively small size of the grain, and the presence of terrestrial weathering veins all presented challenges for removing material for X-ray studies. A 30-micrometer-diameter spindle of material was removed after microdrilling a shallow trench and breaking the spindle with a surgical scalpel. Studies were performed using both a Gandolfi camera to obtain a powder pattern and a four-circle diffractometer to determine the unit

Magnetic particles extracted from manganese nodules: Suggested origin from stony and iron meteorites

Science.gov (United States)

Finkelman, R.B.

1970-01-01

On the basis of x-ray diffraction and electron microprobe data, spherical and ellipsoidal particles extracted from manganese nodules were divided into three groups. Group I particles are believed to be derived from iron meteorites, and Group II particles from stony meteorites. Group III particles are believed to be volcanic in origin.

Mass extinctions and cosmic collisions - a lunar test

International Nuclear Information System (INIS)

Horz, F.

1985-01-01

The possibility has been considered that some or all major mass extinctions in the geologic record of earth are caused by the collision of massive, cosmic objects. Thus, it has been proposed that the unusual concentration of siderophile elements in strata at which the boundary between the Cretaceous (K) and Tertiary (T) geologic time periods has been placed must represent the remnants of a gigantic meteorite. However, a large 65-m.y.-old crater which could have been the result of the impact of this meteorite is not presently known on earth. One approach to evaluate the merits of the collisional hypothesis considered is based on the study of the probability of collision between a cosmic object of a suitable size and the earth. As moon and earth were subject to the same bombardment history and the preservation of craters on the moon is much better than on earth, a consideration of the lunar cratering record may provide crucial information. 32 references

Minor bodies of the Solar system: meteorite orbits, relationship, mirror symmetry in C-distribution

International Nuclear Information System (INIS)

Terent'eva, A.K.

1989-01-01

Population of large meteor bodies having masses from several kilograms up to several tens of tons has been revealed by means of photographic observations of bright fireballs. 39 of 69 objects of this population is meteorites producing. A unique class of meteorite orbits of an extremely short period (the Earth's group) has been found. The analysis of the distributions of minor bodies by Tisserand constant C (the perturbing planet is Jupiter) allowed to make conclusions about possible genetic connections and families inside the complex of minor bodies - comets, asteroids, large meteor bodies including meteorites and meteor streams. About 8 per cent of meteorites and 15 per cent of asteroids of the Amour group may have a cometary origin. Mirror symmetry has been found in C-distribution of minor bodies relative to the gap in the center of which collinear points of libration are located

Prediction of gamma exposure rates in large nuclear craters

Energy Technology Data Exchange (ETDEWEB)

Tami, Thomas M; Day, Walter C [U.S. Army Engineer Nuclear Cratering Group, Lawrence Radiation Laboratory, Livermore, CA (United States)

1970-05-15

In many civil engineering applications of nuclear explosives there is the need to reenter the crater and lip area as soon as possible after the detonation to carry out conventional construction activities. These construction activities, however, must be delayed until the gamma dose rate, or exposure rate, in and around the crater decays to acceptable levels. To estimate the time of reentry for post-detonation construction activities, the exposure rate in the crater and lip areas must be predicted as a function of time after detonation. An accurate prediction permits a project planner to effectively schedule post-detonation activities.

Detection and characterization of buried lunar craters with GRAIL data

Science.gov (United States)

Sood, Rohan; Chappaz, Loic; Melosh, Henry J.; Howell, Kathleen C.; Milbury, Colleen; Blair, David M.; Zuber, Maria T.

2017-06-01

We used gravity mapping observations from NASA's Gravity Recovery and Interior Laboratory (GRAIL) to detect, characterize and validate the presence of large impact craters buried beneath the lunar maria. In this paper we focus on two prominent anomalies detected in the GRAIL data using the gravity gradiometry technique. Our detection strategy is applied to both free-air and Bouguer gravity field observations to identify gravitational signatures that are similar to those observed over buried craters. The presence of buried craters is further supported by individual analysis of regional free-air gravity anomalies, Bouguer gravity anomaly maps, and forward modeling. Our best candidate, for which we propose the informal name of Earhart Crater, is approximately 200 km in diameter and forms part of the northwestern rim of Lacus Somniorum, The other candidate, for which we propose the informal name of Ashoka Anomaly, is approximately 160 km in diameter and lies completely buried beneath Mare Tranquillitatis. Other large, still unrecognized, craters undoubtedly underlie other portions of the Moon's vast mare lavas.

Comets, Asteroids, Meteorites, and the Origin of the Biosphere

Science.gov (United States)

Hoover, Richard B.

2006-01-01

During the past few decades, the delivery of water, organics, and prebiotic chemicals to the Biosphere of Earth during the Hadean (4.5-3.8 Ga) period of heavy bombardment by comets and asteroids has become more widely accepted. Comets are still largely regarded as frigid, pristine bodies of protosolar nebula material that are devoid of liquid water and therefore unsuitable for life. Complex organic compounds have been observed in comets and on the water-rich asteroid 1998 KY26 and near IR observations have indicated the presence of crystalline water ice and ammonia hydrate on the large Kuiper Belt object (50000) Quaoar that has resurfacing suggesting cryovolcanic outgassing. Spacecraft observations of the chemical compositions and characteristics of the nuclei of several comets (Halley, Borrelly, Wild 2, and Tempel 1) have shown that comets contain complex organic chemicals; that water is the predominant volatile; and that extremely high temperatures (approx. 350-400 K) can be reached on the surfae of the very black (albedo approx. 0.03) nuclei of comets when they approach the Sun. Impact craters and pinnacles observed on comet Wild 2 suggest a thick crust. Episodic outbursts and jets from the nuclei of several comets indicate that localized regimes of liquid water and water vapor can periodically exist beneath the comet crust. The Deep Impact mission found the temperature of the nucleus of comet Tempel 1 at 1.5 AU varied from a minimum of 280 plus or minus 8 K the 330K (57 C) on the sunlit side. In this paper it is argued that that pools and films of liquid water exist (within a wide range of temperatures) in cavities and voids just beneath the hot, black crust. The possibility of liquid water existing over a wide range of temperatures significantly enhances the possibility that comets might contain niches suitable for the growth of microbial communities and ecosystems. These regimes would be ideal for the growth of psychrophilic, mesophilic, and thermophilic

Ernst Florens Friedrich Chladni (1756-1827) and the origins of modern meteorite research

Science.gov (United States)

Marvin, Ursula B.

1996-09-01

In 1794, Ernst F. F. Chladni published a 63-page book Über den Ursprung der von Pallas gefundenen und anderer ihr änlicher Eisenmassen und über einige damit in Verbindung stehende Naturerscheinungen in which he proposed that meteor-stones and iron masses enter the atmosphere from cosmic space and form fireballs as they plunge to Earth. These ideas violated two strongly held contemporary beliefs: (1) fragments of rock and metal do not fall from the sky, and (2) no small bodies exist in space beyond the Moon. From the beginning, Chladni was severely criticised for basing his hypotheses on historical eyewitness reports of falls which others regarded as folk tales and for taking gross liberties with the laws of physics. Eight years later, the study of fallen stones and irons was established as a valid field of investigation. Today, some scholars credit Chladni with founding meteoritics as a science; others regard his contributions as scarcely worthy of mention. Writings by his contemporaries suggest that Chladni's book alone would not have led to changes of prevailing theories; thus, he narrowly escaped the fate of those scientists who propose valid hypotheses prematurely. However between 1794 and 1798, four falls of stones were witnessed and widely publicized. There followed a series of epoch-making analyses of fallen stones and "native irons" by the chemist Edward C. Howard and the mineralogist Jacques-Louis de Bournon. They showed that all the stones were much alike in texture and composition but significantly different from the Earth's known crustal rocks. Of primary importance was Howard's discovery of nickel in the irons and the metal grains of the stones. This linked the two as belonging to the same natural phenomenon. The chemical results, published in 1802 February, persuaded leading scientists in England, France, and Germany that bodies fall from the sky. Within a few months, chemists in France reported similar results and a new field of study was

Organics in meteorites - Solar or interstellar?

Science.gov (United States)

Alexander, Conel M. O'D.; Cody, George D.; Fogel, Marilyn; Yabuta, Hikaru

2008-10-01

The insoluble organic material (IOM) in primitive meteorites is related to the organic material in interplanetary dust particles and comets, and is probably related to the refractory organic material in the diffuse interstellar medium. If the IOM is representative of refractory ISM organics, models for how and from what it formed will have to be revised.

Studies on New Halfa Meteorite

International Nuclear Information System (INIS)

Abdu, Y.A.M.

1996-01-01

Mossbauer spectroscopy in the temperature range (295 deg K - 4.2 deg K), electron microprobe, and X-ray diffraction (XRD) measurements have been carried out for the investigation of a Sudanese meteorite, named New Halfa, from a new fall. The specimen contains well defined chondrules which consist mainly of radiating orthopyroxene and olivine. The XRD and the microprobe analysis show the presence of the silicate phases (olivine and pyroxene), iron sulphide (troilite), and Fe-Ni alloys (kamacite and taenite). The olivine appears to have a constant composition throughout the specimen, whereas pyroxene have a varying composition and both orthopyroxene (which is the dominant pyroxene) and clinopyroxene were present. The microprobe trace of Ni concentration across a kamacite-taenite-kamacite area shows a high Ni concentration at the interface between kamacite and taenite phases. The room temperature Mossbauer spectrum is fitted with with three sextets and two doublets. The sextets were assigned Fe in troilite, kamacite and taenite, and the two doublets to Fe 2+ in olivine and pyroxene (no Fe 3+ was found). The Mossbauer spectrum at 4.2 K shows that olivine, which is paramagnetic at room temperature, is magnetic showing relaxation effects. The Mossbauer data of this meteorite confirm it as an ordinary L-chondrite. (author). 19 refs., 5 tabs., 17 figs

The Innisfree meteorite: Dynamical history of the orbit - Possible family of meteor bodies

Science.gov (United States)

Galibina, I. V.; Terent'eva, A. K.

1987-09-01

Evolution of the Innisfree meteorite orbit caused by secular perturbations is studied over the time interval of 500000 yrs (from the current epoch backwards). Calculations are made by the Gauss-Halphen-Gorjatschew method taking into account perturbations from the four outer planets - Jupiter, Saturn, Uranus and Neptune. In the above mentioned time interval the meteorite orbit has undergone no essential transformations. The Innisfree orbit intersected in 91 cases the Earth orbit and in 94 - the Mars orbit. A system of small and large meteor bodies (producing ordinary meteors and fireballs) which may be genetically related to the Innisfree meteorite has been found, i.e. there probably exists an Innisfree family of meteor bodies.

Geomorphometric analysis of selected Martian craters using polar coordinate transformation

Science.gov (United States)

Magyar, Zoltán; Koma, Zsófia; Székely, Balázs

2016-04-01

Centrally symmetric landform elements are very common features on the surface of the planet Mars. The most conspicuous ones of them are the impact craters of various size. However, a closer look on these features reveals that they show often asymmetric patterns as well. These are partially related to the geometry of the trajectory of the impacting body, but sometimes it is a result of surface processes (e.g., freeze/thaw cycles, mass movements). Geomorphometric studies have already been carried out to reveal these pecularities. Our approach, the application of polar coordinate transformation (PCT) very sensitively enhances the non-radial and non-circular shapes. We used digital terrain models (DTMs) derived from the ESA Mars Express HRSC imagery. The original DTM or its derivatives (e.g. slope angle or aspect) are PCT transformed. We analyzed the craters inter alia with scattergrams in polar coordinates. The resulting point cloud can be used directly for the analysis, but in some cases an interpolation should be applied to enhance certain non-circular features (especially in case of smaller craters). Visual inspection of the crater slopes, coloured by the aspect, reveals smaller features. Some of them are processing artefacts, but many of them are related to local undulations in the topography or indications of mass movements. In many cases the undulations of the crater rim are due to erosional processes. The drawbacks of the technology are related to the uneven resolution of the projected image: features in the crater centre should be left out from the analysis because PCT has a low resolution around the projection center. Furthermore, the success of the PCT depends on the correct definition of the projection centre: erroneously centered images are not suitable for analysis. The PCT transformed images are also suitable for radial averaging and calculation of standard deviations, resulting in typical, comparable craters shapes. These studies may lead to a deeper

Long-Term Recovery of Life in the Chicxulub Crater

Science.gov (United States)

Lowery, C.; Jones, H.; Bralower, T. J.; Smit, J.; Rodriguez-Tovar, F. J.; Whalen, M. T.; Owens, J. D.; Expedition 364 Science Party, I. I.

2017-12-01

The Chicxulub Crater on the Yucatán Peninsula of Mexico was formed by the impact of an asteroid 66 Ma that caused the extinction of 75% of genera on Earth. Immediately following the impact, the decimated ecosystem began the long process of recovery, both in terms of primary productivity and species diversity. This well-documented process was heterogeneous across the world ocean, but until the present time it has been inaccessible at ground zero of the impact. IODP/ICDP Exp. 364 recovered 9.5 m of pelagic limestone spanning the entire Paleocene, including a continuous section spanning the first 5 myr following the impact. The Chicxulub Crater is the largest known marine impact crater on Earth, and the recovery of the ecosystem presented here is the first such record of long-term primary succession in the sterile zone of a large impact crater. Planktic and benthic foraminifera, calcareous nannoplankton, calcispheres, bioturbation, and geochemical proxies all indicate that export productivity in the Chicxulub Crater recovered rapidly (within 30 kyr) following the impact. Recovery in terms of diversity and species abundance took much longer, and varied between groups. Planktic foraminifera quickly diversified, with all common Paleocene tropical/subtropical species appearing roughly when expected. Trace fossils appear rapidly after the event, with a progressive recovery through the lowermost Paleocene. Calcareous nannoplankton took much longer to recover, and disaster taxa like Braarudosphaera dominated the assemblage well into the late Paleocene. Paleoecology and geochemistry relate these trends to oceanographic conditions within the Chicxulub Crater. Planktic foraminifera from known depth habitats, including Morozovellids, Acarininids, Chiloguembelinids, and Subbotinids, track changes in the water column structure and paleoredox conditions within the crater. Diverse and abundant macro- and microbenthic organisms indicate food availability and good oxygen conditions

Relaxed impact craters on Ganymede: Regional variation and high heat flows

Science.gov (United States)

Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.

2018-05-01

Viscously relaxed craters provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed craters in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the crater with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed craters indicates high heat flows-in excess of 30-40 mW m-2 over 2 Gyr, with many small (heat flows. Crater relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.

Lunar Meteorites Sayh Al Uhaymir 449 and Dhofar 925, 960, and 961: Windows into South Pole

Science.gov (United States)

Ziegler, Ryan A.; Jolliff, B. L.; Korotev, R. L.

2013-01-01

In 2003, three lunar meteorites were collected in close proximity to each other in the Dhofar region of Oman: Dhofar 925 (49 g), Dhofar 960 (35 g), and Dhofar 961 (22 g). In 2006, lunar meteorite Sayh al Uhaymir (SaU) 449 (16.5 g) was found about 100 km to the NE. Despite significant differences in the bulk composition of Dhofar 961 relative to Dhofar 925/960 and SaU 449 (which are identical to each other), these four meteorites are postulated to be paired based on their find locations, bulk composition, and detailed petrographic analysis. Hereafter, they will collectively be referred to as the Dhofar 961 clan. Comparison of meteorite and component bulk compositions to Lunar Prospector 5-degree gamma-ray data suggest the most likely provenance of this meteorite group is within the South Pole-Aitken Basin. As the oldest, largest, and deepest recognizable basin on the Moon, the composition of the material within the SPA basin is of particular importance to lunar science. Here we review and expand upon the geochemistry and petrography of the Dhofar 961 clan and assess the likelihood that these meteorites come from within the SPA basin based on their bulk compositions and the compositions and characteristics of the major lithologic components found within the breccia.

Mars Climate History: Insights From Impact Crater Wall Slope Statistics

Science.gov (United States)

Kreslavsky, Mikhail A.; Head, James W.

2018-02-01

We use the global distribution of the steepest slopes on crater walls derived from Mars Orbiter Laser Altimeter profile data to assess the magnitudes of degradational processes with latitude, altitude, and time. We independently confirm that Amazonian polar/high-latitude crater slope modification is substantial, but that craters in the low latitudes have essentially escaped significant slope modification since the Early Hesperian. We find that the total amount of crater wall degradation in the Late Noachian is very small in comparison to the circumpolar regions in the Late Amazonian, an observation that we interpret to mean that the Late Noachian climate was not characterized by persistent and continuous warm and wet conditions. A confirmed elevational zonality in degradation in the Early Hesperian is interpreted to mean that the atmosphere was denser than today.

Oblique view of crater Theophilus at northwest edge of Sea of Nectar

Science.gov (United States)

1969-01-01

An Apollo 11 oblique view of the large crater Theophilus located at the northwest edge of the Sea of Nectar on the lunar nearside. Theophilus is about 60 statute miles in diameter. the smooth area is Mare Nectaris. The smaller crater Madler, about 14 statute miles in diameter, is located to the east of Theophilus. Visible in the background are the large crater Fracastorius and the smaller crater Beaumont. The coordinates of the center of this photograph are 29 degrees east longitude and 11 degrees south latitude.

Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars

Science.gov (United States)

Grotzinger, J. P.; Gupta, S.; Malin, M. C.; Rubin, D. M.; Schieber, J.; Siebach, K.; Sumner, D. Y.; Stack, K. M.; Vasavada, A. R.; Arvidson, R. E.; Calef, F.; Edgar, L.; Fischer, W. F.; Grant, J. A.; Griffes, J.; Kah, L. C.; Lamb, M. P.; Lewis, K. W.; Mangold, N.; Minitti, M. E.; Palucis, M.; Rice, M.; Williams, R. M. E.; Yingst, R. A.; Blake, D.; Blaney, D.; Conrad, P.; Crisp, J.; Dietrich, W. E.; Dromart, G.; Edgett, K. S.; Ewing, R. C.; Gellert, R.; Hurowitz, J. A.; Kocurek, G.; Mahaffy, P.; McBride, M. J.; McLennan, S. M.; Mischna, M.; Ming, D.; Milliken, R.; Newsom, H.; Oehler, D.; Parker, T. J.; Vaniman, D.; Wiens, R. C.; Wilson, S. A.

2015-10-01

The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

Terrestrial microbes in martian and chondritic meteorites

Science.gov (United States)

Airieau, S.; Picenco, Y.; Andersen, G.

2007-08-01

Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

[Study of enhancement effect of laser-induced crater on plasma radiation].

Science.gov (United States)

Chen, Jin-Zhong; Zhang, Xiao-Ping; Guo, Qing-Lin; Su, Hong-Xin; Li, Guang

2009-02-01

Single pulses exported from high-energy neodymium glass laser were used to act on the same position of soil sample surface repeatedly, and the plasma emission spectra generated from sequential laser pulse action were collected by spectral recording system. The experimental results show that the laser-induced soil plasma radiation was enhanced continuously under the confinement effect of the crater walls, and the line intensities and signal-to-background ratios both had different improvements along with increasing the number of acting pulses. The photographs of the plasma image and crater appearance were taken to study the plasma shape, laser-induced crater appearance, and the mass of the ablated sample. The internal mechanism behind that laser-induced crater enhanced plasma radiation was researched. Under the sequential laser pulse action, the forming plasma as a result enlarges gradually first, leading to distortion at the trail of plasma plume, and then, its volume diminishes slowly. And also, the color of the plasma changes from buff to white gradually, which implies that the temperature increases constantly. The laser-induced crater had a regular shape, that is, the diameter increased from its bottom to top gradually, thus forming a taper. The mass of the laser-ablated substance descends along with increasing the amount of action pulse. Atomization degree of vaporized substance was improved in virtue of the crater confinement effect, Fresnel absorption produced from the crater walls reflection, and the inverse bremsstrahlung, and the plasma radiation intensity was enhanced as a result.

Preferential occupation of pyroxene sites by iron in diogenite meteorites

International Nuclear Information System (INIS)

Verma, H. C.; Tewari, V. C.; Paliwal, B. S.; Tripathi, R. P.

2008-01-01

Three diogenite meteorites ALHA77256-121, Tatahounie and Bilanga are studied using Moessbauer spectroscopy to look at the iron occupancy in the two inequivalent pyroxene sites. Though the three meteorites belong to three different conditions, one is an Antarctica find, one is 75 years old fall and one is a recent fall, the iron occupancy in pyroxene sites is very similar. Fe 2+ occupies only the less distorted site and hence a single sharp doublet is observed in the Moessbauer spectra of all these samples. In contrast eucrites show a distribution of iron ions in the two sites of pyroxenes.

Characterization of the Morphometry of Impact Craters Hosting Polar Deposits in Mercury's North Polar Region

Science.gov (United States)

Talpe Matthieu; Zuber, Maria T.; Yang, Di; Neumann, Gregory A.; Solomon, Sean C.; Mazarico, Erwan; Vilas, Faith

2012-01-01

Earth-based radar images of Mercury show radar-bright material inside impact craters near the planet s poles. A previous study indicated that the polar-deposit-hosting craters (PDCs) at Mercury s north pole are shallower than craters that lack such deposits. We use data acquired by the Mercury Laser Altimeter on the MESSENGER spacecraft during 11 months of orbital observations to revisit the depths of craters at high northern latitudes on Mercury. We measured the depth and diameter of 537 craters located poleward of 45 N, evaluated the slopes of the northern and southern walls of 30 PDCs, and assessed the floor roughness of 94 craters, including nine PDCs. We find that the PDCs appear to have a fresher crater morphology than the non-PDCs and that the radar-bright material has no detectable influence on crater depths, wall slopes, or floor roughness. The statistical similarity of crater depth-diameter relations for the PDC and non-PDC populations places an upper limit on the thickness of the radar-bright material (< 170 m for a crater 11 km in diameter) that can be refined by future detailed analysis. Results of the current study are consistent with the view that the radar-bright material constitutes a relatively thin layer emplaced preferentially in comparatively young craters.

Cratering Studies in Thin Plastic Films

Science.gov (United States)

Shu, A. J.; Bugiel, S.; Gruen, E.; Hillier, J.; Horanyi, M.; Munsat, T. L.; Srama, R.

2013-12-01

Thin plastic films, such as Polyvinylidene Fluoride (PVDF), have been used as protective coatings or dust detectors on a number of missions including the Dust Counter and Mass Analyzer (DUCMA) instrument on Vega 1 and 2, the High Rate Detector (HRD) on the Cassini Mission, and the Student Dust Counter (SDC) on New Horizons. These types of detectors can be used on the lunar surface or in lunar orbit to detect dust grain size distributions and velocities. Due to their low power requirements and light weight, large surface area detectors can be built for observing low dust fluxes. The SDC dust detector is made up of a permanently polarized layer of PVDF coated on both sides with a thin layer (≈ 1000 Å) of aluminum nickel. The operation principle is that a micrometeorite impact removes a portion of the metal surface layer exposing the permanently polarized PVDF underneath. This causes a local potential near the crater changing the surface charge of the metal layer. The dimensions and shape of the crater determine the strength of the potential and thus the signal generated by the PVDF. The theoretical basis for signal interpretation uses a crater diameter scaling law which was not intended for use with PVDF. In this work, a crater size scaling law has been experimentally determined, and further simulation work is being done to enhance our understanding of the mechanisms of crater formation. LS-Dyna, a smoothed particle hydrodynamics (SPH) code from the Livermore Software Technology Corp. was chosen to simulate micrometeorite impacts. SPH is known to be well suited to the large deformities found in hypervelocity impacts. It is capable of incorporating key physics phenomena, including fracture, heat transfer, melting, etc. Furthermore, unlike Eulerian methods, SPH is gridless allowing large deformities without the inclusion of unphysical erosion algorithms. Material properties are accounted for using the Grüneisen Equation of State. The results of the SPH model can

Relaxed impact craters on Ganymede: Regional variation and high heat flows

Science.gov (United States)

Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.

2018-01-01

Viscously relaxed craters provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed craters in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the crater with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed craters indicates high heat flows—in excess of 30–40 mW m−2 over 2 Gyr, with many small (heat flows. Crater relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.

An ion microprobe study of CAIs from CO3 meteorites. [Abstract only

Science.gov (United States)

Russell, S. S.; Greenwood, R. C.; Fahey, A. J.; Huss, G. R.; Wasserburg, G. J.

1994-01-01

When attempting to interpret the history of Ca, Al-rich inclusions (CAIs) it is often difficult to distinguish between primary features inherited from the nebula and those produced during secondary processing on the parent body. We have undertaken a systematic study of CAIs from 10 CO chondrites, believed to represent a metamorphic sequence with the goal of distinguishing primary and secondary features. ALHA 77307 (3.0), Colony (3.0), Kainsaz (3.1), Felix (3.2), ALH 82101 (3.3), Ornans (3.3), Lance (3.4), ALHA 77003 (3.5), Warrenton (3.6), and Isna (3.7) were examined by Scanning Electron Microscopy (SEM) and optical microscopy. We have identified 141 CAIs within these samples, and studied in detail the petrology of 34 inclusions. The primary phases in the lower petrologic types are spinel, melilite, and hibonite. Perovskite, FeS, ilmenite, anorthite, kirschsteinite, and metallic Fe are present as minor phases. Melilite becomes less abundant in higher petrologic types and was not detected in chondrites of type 3.5 and above, confirming previous reports that this mineral easily breaks down during heating. Iron, an element that would not be expected to condense at high temperatures, has a lower abundance in spinel from low-petrologic-type meteorites than those of higher grade, and CaTiO3 is replaced by FeTiO3 in meteorites of higher petrologic type. The abundance of CAIs is similar in each meteorite. Eight inclusions have been analyzed by ion probe. The results are summarized. The results obtained to date show that CAIs in CO meteorites, like those from other meteorite classes, contain Mg* and that Mg in some inclusions has been redistributed.

Ejecta from single-charge cratering explosions

Energy Technology Data Exchange (ETDEWEB)

Carlson, R H

1970-05-15

The objective was to obtain experimental data tracing the location of ejecta to its origin within the crater region. The experiment included ten high-explosive spherical charges weighing from 8 to 1000 pounds and detonated in a playa dry lake soil on the Tonopah Test Range. Each event included from 24 to 40 locations of distinctly different tracer material embedded in a plane in the expected crater region. Tracers consisted of glass, ceramic and bugle beads, chopped metal, and plastic wire. Results of this experiment yielded data on tracer dispersion as a function of charge weight, charge burial depth and tracer emplacement position. Tracer pattern parameters such as center-of-tracer mass, range to center-of-tracer mass, and angle to center-of-tracer mass were determined. There is a clear tendency for range (to center-of-tracer mass) and the size of the dispersion pattern to decrease as tracer emplacement depth increases. Increasing tracer emplacement depth and range tends to decrease the area over which tracers are dispersed on the ground surface. Tracers at the same scaled position relative to the charge were deposited closer to the crater (on a scaled basis) as charge weight was increased. (author)

Potential for observing and discriminating impact craters and comparable volcanic landforms on Magellan radar images

International Nuclear Information System (INIS)

Ford, J.P.

1989-01-01

Observations of small terrestrial craters by Seasat synthetic aperture radar (SAR) at high resolution (approx. 25 m) and of comparatively large Venusian craters by Venera 15/16 images at low resolution (1000 to 2000 m) and shorter wavelength show similarities in the radar responses to crater morphology. At low incidence angles, the responses are dominated by large scale slope effects on the order of meters; consequently it is difficult to locate the precise position of crater rims on the images. Abrupt contrasts in radar response to changing slope (hence incidence angle) across a crater produce sharp tonal boundaries normal to the illumination. Crater morphology that is radially symmetrical appears on images to have bilateral symmetry parallel to the illumination vector. Craters are compressed in the distal sector and drawn out in the proximal sector. At higher incidence angles obtained with the viewing geometry of SIR-A, crater morphology appears less compressed on the images. At any radar incidence angle, the distortion of a crater outline is minimal across the medial sector, in a direction normal to the illumination. Radar bright halos surround some craters imaged by SIR-A and Venera 15 and 16. The brightness probably denotes the radar response to small scale surface roughness of the surrounding ejecta blankets. Similarities in the radar responses of small terrestrial impact craters and volcanic craters of comparable dimensions emphasize the difficulties in discriminating an impact origin from a volcanic origin in the images. Similar difficulties will probably apply in discriminating the origin of small Venusian craters, if they exist. Because of orbital considerations, the nominal incidence angel of Magellan radar at the center of the imaging swath will vary from about 45 deg at 10 deg N latitude to about 16 deg at the north pole and at 70 deg S latitude. Impact craters and comparable volcanic landforms will show bilateral symmetry

"Sweating meteorites"—Water-soluble salts and temperature variation in ordinary chondrites and soil from the hot desert of Oman

Science.gov (United States)

Zurfluh, Florian J.; Hofmann, Beda A.; Gnos, Edwin; Eggenberger, Urs

2013-10-01

The common appearance of hygroscopic brine ("sweating") on ordinary chondrites (OCs) from Oman during storage under room conditions initiated a study on the role of water-soluble salts on the weathering of OCs. Analyses of leachates from OCs and soils, combined with petrography of alteration features and a 11-month record of in situ meteorite and soil temperatures, are used to evaluate the role of salts in OC weathering. Main soluble ions in soils are Ca2+, SO42-, HCO3-, Na+, and Cl-, while OC leachates are dominated by Mg2+ (from meteoritic olivine), Ca2+ (from soil), Cl- (from soil), SO42- (from meteoritic troilite and soil), and iron (meteoritic). "Sweating meteorites" mainly contain Mg2+ and Cl-. The median Na/Cl mass ratio of leachates changes from 0.65 in soils to 0.07 in meteorites, indicating the precipitation of a Na-rich phase or loss of an efflorescent Na-salt. The total concentrations of water-soluble ions in bulk OCs ranges from 600 to 9000 μg g-1 (median 2500 μg g-1) as compared to 187-14140 μg g-1 in soils (median 1148 μg g-1). Soil salts dissolved by rain water are soaked up by meteorites by capillary forces. Daily heating (up to 66.3 °C) and cooling of the meteorites cause a pumping effect, resulting in a strong concentration of soluble ions in meteorites over time. The concentrations of water-soluble ions in meteorites, which are complex mixtures of ions from the soil and from oxidation and hydrolysis of meteoritic material, depend on the degree of weathering and are highest at W3. Input of soil contaminants generally dominates over the ions mobilized from meteorites. Silicate hydrolysis preferentially affects olivine and is enhanced by sulfide oxidation, producing local acidic conditions as evidenced by jarosite. Plagioclase weathering is negligible. After completion of troilite oxidation, the rate of chemical weathering slows down with continuing Ca-sulfate contamination.

Enantiomer excesses of rare and common sugar derivatives in carbonaceous meteorites

OpenAIRE

Cooper, George; Rios, Andro C.

2016-01-01

The majority of biological sugars and their derivatives contain higher abundances of the “d” mirror-image forms relative to the “l” forms. For example, nucleic acids are composed of only d sugars. Carbonaceous meteorites can potentially assist in understanding the long-sought origin of such phenomena; They preserve a record of the earliest (∼4.5 Gy) chemical processes in the Solar System. To date, there have been no systematic studies of d/l (i.e., enantiomer) ratios of meteoritic sugar deriv...

Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars.

Science.gov (United States)

Grotzinger, J P; Gupta, S; Malin, M C; Rubin, D M; Schieber, J; Siebach, K; Sumner, D Y; Stack, K M; Vasavada, A R; Arvidson, R E; Calef, F; Edgar, L; Fischer, W F; Grant, J A; Griffes, J; Kah, L C; Lamb, M P; Lewis, K W; Mangold, N; Minitti, M E; Palucis, M; Rice, M; Williams, R M E; Yingst, R A; Blake, D; Blaney, D; Conrad, P; Crisp, J; Dietrich, W E; Dromart, G; Edgett, K S; Ewing, R C; Gellert, R; Hurowitz, J A; Kocurek, G; Mahaffy, P; McBride, M J; McLennan, S M; Mischna, M; Ming, D; Milliken, R; Newsom, H; Oehler, D; Parker, T J; Vaniman, D; Wiens, R C; Wilson, S A

2015-10-09

The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp). Copyright © 2015, American Association for the Advancement of Science.

Hypervelocity impact cratering calculations

Science.gov (United States)

Maxwell, D. E.; Moises, H.

1971-01-01

A summary is presented of prediction calculations on the mechanisms involved in hypervelocity impact cratering and response of earth media. Considered are: (1) a one-gram lithium-magnesium alloys impacting basalt normally at 6.4 km/sec, and (2) a large terrestrial impact corresponding to that of Sierra Madera.

Sparking young minds with Moon rocks and meteorites

Science.gov (United States)

Taylor, G. Jeffrey; Lindstrom, Marilyn M.

1993-01-01

What could be more exciting than seeing pieces of other worlds? The Apollo program left a legacy of astounding accomplishments and precious samples. Part of the thrill of those lunar missions is brought to schools by the lunar sample educational disks, which contain artifacts of six piloted trips to the Moon. Johnson Space Center (JSC) is preparing 100 new educational disks containing pieces of meteorites collected in Antarctica. These represent chunks of several different asteroids, that were collected in one of the most remote, forbidding environments on Earth. These pieces of the Moon and asteroids represent the products of basic planetary processes (solar nebular processes, initial differentiation, volcanism, and impact), and, in turn, these processes are controlled by basic physical and chemical processes (energy, energy transfer, melting, buoyancy, etc.). Thus, the lunar and meteorite sample disks have enormous educational potential. New educational materials are being developed to accompany the disks. Present materials are not as effective as they could be, especially in relating samples to processes and to other types of data such as spectral studies and photogeology. Furthermore, the materials are out of date. New background materials will be produced for teachers, assembling slide sets with extensive captions, and devising numerous hands-on classroom activities to do while the disks are at a school and before and after they arrive. The classroom activities will be developed by teams of experienced teachers working with lunar and meteorite experts.

The Sample at Mars Analysis (SAM) Detections of CO2 and CO in Sedimentary Material from Gale Crater, Mars: Implications for the Presence of Organic Carbon and Microbial Habitability on Mars

Science.gov (United States)

Sutter, Brad; Eigenbrode, Jennifer L.; Steele, Andrew; Ming, Douglas W.

2016-01-01

Sedimentary rock samples heated to 860 degrees Centigrade in the SAM (Sample at Mars) instrument evolved CO2 and CO indicating the presence of organic-carbon(C) in Gale Crater materials. Martian or exogenous (meteoritic, interplanetary dust) CO2 and CO could be derived from combustion of simple organics (less than 300 degrees Centigrade), complex refractory organics/amorphous carbon (300-600 degrees Centigrade), and/or magmatic carbon (greater than 600 degrees Centigrade) as result of thermal decomposition of Gale Crater perchlorates, and sulfates present that produce O2. Oxidized organic compounds could also evolve CO2 and CO over broad temperature range (150 to 800 degrees Centigrade) and such organics are expected on Mars via exogenous sources. Alternatively, organic-C could also have been oxidized to carboxylic acids [e.g, mellitic acid (RCOOH), acetate (CH3CO2-), and oxalates (C2O42-)] by oxidative radiolytic weathering, or other oxidation processes. The presence of oxidized organics is consistent with the limited detection of reduced organic-C phases by the SAM-gas chromatography. Organic-C content as determined by CO2 and CO contents could range between 800 and 2400 parts per million C indicating that substantial organic-C component is present in Gale Crater. There are contributions from SAM background however, even in worst-case scenarios, this would only account for as much as half of the detected CO2 and CO. Nevertheless, if organic-C levels were assumed to have existed in a reduced form on ancient Mars and this was bioavailable C, then less than 1 percent of C in Gale Crater sediments could have supported an exclusively heterotrophic microbial population of 1 by 10 (sup 5) cells per gram sediment (assumes 9 by 10 (sup -7) microgram per cell and 0.5 micrograms C per microgram cell). While other essential nutrients (e.g., S and P) could be limiting, organic-C contents, may have been sufficient to support limited heterotrophic microbial populations on

The Mechanics of Peak-Ring Impact Crater Formation from the IODP-ICDP Expedition 364

Science.gov (United States)

Melosh, H.; Collins, G. S.; Morgan, J. V.; Gulick, S. P. S.

2017-12-01

The Chicxulub impact crater is one of very few peak-ring impact craters on Earth. While small (less than 3 km on Earth) impact craters are typically bowl-shaped, larger craters exhibit central peaks, which in still larger (more than about 100 km on Earth) craters expand into mountainous rings with diameters close to half that of the crater rim. The origin of these peak rings has been contentious: Such craters are far too large to create in laboratory experiments and remote sensing of extraterrestrial examples has not clarified the mechanics of their formation. Two principal models of peak ring formation are currently in vogue, the "nested crater" model, in which the peak ring originates at shallow depths in the target, and the "dynamic collapse" model in which the peak ring is uplifted at the base of a collapsing, over-steepened central peak and its rocks originate at mid-crustal depths. IODP-ICDP Expedition 364 sought to elucidate, among other important goals, the mechanics of peak ring formation in the young (66 Myr), fresh, but completely buried Chicxulub impact crater. The cores from this borehole now show unambiguously that the rocks in the Chicxulub peak ring originated at mid-crustal depths, apparently ruling out the nested crater model. These rocks were shocked to pressures on the order of 10-35 GPa and were so shattered that their densities and seismic velocities now resemble those of sedimentary rocks. The morphology of the final crater, its structure as revealed in previous seismic imaging, and the results from the cores are completely consistent with modern numerical models of impact crater excavation and collapse that incorporate a model for post-impact weakening. Subsequent to the opening of a ca. 100 km diameter and 30 km deep transient crater, this enormous hole in the crust collapsed over a period of about 10 minutes. Collapse was enabled by movement of the underlying rocks, which briefly behaved in the manner of a high-viscosity fluid, a brittle

Imaging the Buried Chicxulub Crater with Gravity Gradients and Cenotes

Science.gov (United States)

Hildebrand, A. R.; Pilkington, M.; Halpenny, J. F.; Ortiz-Aleman, C.; Chavez, R. E.; Urrutia-Fucugauchi, J.; Connors, M.; Graniel-Castro, E.; Camara-Zi, A.; Vasquez, J.

1995-09-01

Differing interpretations of the Bouguer gravity anomaly over the Chicxulub crater, Yucatan Peninsula, Mexico, have yielded diameter estimates of 170 to 320 km. Knowing the crater's size is necessary to quantify the lethal perturbations to the Cretaceous environment associated with its formation. The crater's size (and internal structure) is revealed by the horizontal gradient of the Bouguer gravity anomaly over the structure, and by mapping the karst features of the Yucatan region. To improve our resolution of the crater's gravity signature we collected additional gravity measurements primarily along radial profiles, but also to fill in previously unsurveyed areas. Horizontal gradient analysis of Bouguer gravity data objectively highlights the lateral density contrasts of the impact lithologies and suppresses regional anomalies which may obscure the gravity signature of the Chicxulub crater lithologies. This gradient technique yields a striking circular structure with at least 6 concentric gradient features between 25 and 85 km radius. These features are most distinct in the southwest probably because of denser sampling of the gravity field. Our detailed profiles detected an additional feature and steeper gradients (up to 5 mGal/km) than the original survey. We interpret the outer four gradient maxima to represent concentric faults in the crater's zone of slumping as is also revealed by seismic reflection data. The inner two probably represent the margin of the central uplift and the peak ring and or collapsed transient cavity. Radial gradients in the SW quadrant over the inferred ~40 km-diameter central uplift (4) may represent structural "puckering" as revealed at eroded terrestrial craters. Gradient features related to regional gravity highs and lows are visible outside the crater, but no concentric gradient features are apparent at distances > 90 km radius. The marginal gradient features may be modelled by slump faults as observed in large complex craters on

Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) with Raman Imaging Applied to Lunar Meteorites.

Science.gov (United States)

Smith, Joseph P; Smith, Frank C; Booksh, Karl S

2018-03-01

Lunar meteorites provide a more random sampling of the surface of the Moon than do the returned lunar samples, and they provide valuable information to help estimate the chemical composition of the lunar crust, the lunar mantle, and the bulk Moon. As of July 2014, ∼96 lunar meteorites had been documented and ten of these are unbrecciated mare basalts. Using Raman imaging with multivariate curve resolution-alternating least squares (MCR-ALS), we investigated portions of polished thin sections of paired, unbrecciated, mare-basalt lunar meteorites that had been collected from the LaPaz Icefield (LAP) of Antarctica-LAP 02205 and LAP 04841. Polarized light microscopy displays that both meteorites are heterogeneous and consist of polydispersed sized and shaped particles of varying chemical composition. For two distinct probed areas within each meteorite, the individual chemical species and associated chemical maps were elucidated using MCR-ALS applied to Raman hyperspectral images. For LAP 02205, spatially and spectrally resolved clinopyroxene, ilmenite, substrate-adhesive epoxy, and diamond polish were observed within the probed areas. Similarly, for LAP 04841, spatially resolved chemical images with corresponding resolved Raman spectra of clinopyroxene, troilite, a high-temperature polymorph of anorthite, substrate-adhesive epoxy, and diamond polish were generated. In both LAP 02205 and LAP 04841, substrate-adhesive epoxy and diamond polish were more readily observed within fractures/veinlet features. Spectrally diverse clinopyroxenes were resolved in LAP 04841. Factors that allow these resolved clinopyroxenes to be differentiated include crystal orientation, spatially distinct chemical zoning of pyroxene crystals, and/or chemical and molecular composition. The minerals identified using this analytical methodology-clinopyroxene, anorthite, ilmenite, and troilite-are consistent with the results of previous studies of the two meteorites using electron microprobe

Comets as parent bodies of CI1 carbonaceous meteorites and possible habitats of ice-microbes

Science.gov (United States)

Wickramasinghe, N. Chandra; Wickramasinghe, Janaki T.; Wallis, Jamie; Hoover, Richard B.; Rozanov, Alexei Y.

2011-10-01

Recent studies of comets and cometary dust have confirmed the presence of biologically relevant organic molecules along with clay minerals and water ice. It is also now well established by deuterium/hydrogen ratios that the CI1 carbonaceous meteorites contain indigenous extraterrestrial water. The evidence of extensive aqueous alteration of the minerals in these meteorites led to the hypothesis that water-bearing asteroids or comets represent the parent bodies of the CI1 (and perhaps CM2) carbonaceous meteorites. These meteorites have also been shown to possess a diverse array of complex organics and chiral and morphological biomarkers. Stable isotope studies by numerous independent investigators have conclusively established that the complex organics found in these meteorites are both indigenous and extraterrestrial in nature. Although the origin of these organics is still unknown, some researchers have suggested that they originated by unknown abiotic mechanisms and may have played a role in the delivery of chiral biomolecules and the origin of life on Early Earth. In this paper we review these results and investigate the thermal history of comets. We show that permanent as well as transient domains of liquid water can be maintained on a comet under a plausible set of assumptions. With each perihelion passage of a comet volatiles are preferentially released, and during millions of such passages the comet could shed crustal debris that may survive transit through the Earth's atmosphere as a carbonaceous meteorite. We review the current state of knowledge of comets and carbonaceous meteorites. We also present the results of recent studies on the long-term viability of terrestrial ice-microbiota encased in ancient glacial ice and permafrost. We suggest that the conditions which have been observed to prevail on many comets do not preclude either survivability (or even the active metabolism and growth) of many types of eukaryotic and prokaryotic microbial

Comets as Parent Bodies of CI1 Carbonaceous Meteorites and Possible Habitats of Ice-Microbiota

Science.gov (United States)

Wickramasinghe, N. Chandra; Wallis, Daryl H.; Rozanov, Alexei Yu.; Hoover, Richard B.

2011-01-01

Recent studies of comets and cometary dust have confirmed the presence of biologically relevant organic molecules along with clay minerals and water ice. It is also now well established by deuterium/hydrogen ratios that the CI1 carbonaceous meteorites contain indigenous extraterrestrial water. The evidence of extensive aqueous alteration of the minerals in these meteorites led to the hypothesis that water-bearing asteroids or comets represent the parent bodies of the CI1 (and perhaps CM2) carbonaceous meteorites. These meteorites have also been shown to possess a diverse array of complex organics and chiral and morphological biomarkers. Stable isotope studies by numerous independent investigators have conclusively established that the complex organics found in these meteorites are both indigenous and extraterrestrial in nature. Although the origin of these organics is still unknown, some researchers have suggested that they originated by unknown abiotic mechanisms and may have played a role in the delivery of chiral biomolecules and the origin of life on Early Earth. In this paper we review these results and investigate the thermal history of comets. We show that permanent as well as transient domains of liquid water can be maintained on a comet under a plausible set of assumptions. With each perihelion passage of a comet volatiles are preferentially released, and during millions of such passages the comet could shed crustal debris that may survive transit through the Earth s atmosphere as a carbonaceous meteorite. We review the current state of knowledge of comets and carbonaceous meteorites. We also present the results of recent studies on the long-term viability of terrestrial ice-microbiota encased in ancient glacial ice and permafrost. We suggest that the conditions which have been observed to prevail on many comets do not preclude either survivability (or even the active metabolism and growth) of many types of eukaryotic and prokaryotic microbial

The meteoritic record of presolar and early solar system organic chemistry. [Abstract only

Science.gov (United States)

Cronin, John R.; Pizzarello, Sandra

1994-01-01

Carbon, hydrogen, and nitrogen isotopic analyses of various classes of organic compounds done in collaboration with Epstein and Krishnamurthy (Caltech) have shown these compounds to be enriched to varying degrees in the heavier isotopes. These results, in particular the large deuterium enrichments, have been interpreted as indicating an interstellar origin for the meteorite compounds or their precursors. Such isotopic fractionations, of hydrogen especially, are characteristic of low temperature ion-molecule reactions in cold interstellar clouds. There is also evidence from the large corresponding suites of alpha-amino and alpha-hydroxy acids found in meteorites suggesting that aqueous phase chemistry on the meteorite parent body played an important role in the formation of these compounds. These data support the hypothesis that interstellar compounds survived in the solar nebula at a radial distance corresponding to the asteroid belt, were incorporated into the parent body in icy, volatile-rich, planetesinals, and underwent further reactions during a period of aqueous activity within the early parent body to give the present suite of meteorite compounds. This formation hypothesis will be discussed and the results of recent isotopic and molecular analyses bearing on it will be presented.

Determination of Meteorite Porosity Using Liquid Nitrogen

Science.gov (United States)

Kohout, T.; Kletetschka, G.; Pesonen, L. J.; Wasilewski, P. J.

2005-01-01

We introduce a new harmless method for porosity measurement suitable for meteorite samples. The method is a modification of the traditional Archimedean method based on immersion of the samples in a liquid medium like water or organic liquids. In our case we used liquid nitrogen for its chemically inert characteristics.

Asteroids and Meteorites from Venus? Only the Earth Goddess Knows

Science.gov (United States)

Dones, Henry; Zahnle, Kevin J.; Alvarellos, José L.

2018-04-01

No meteorites from Venus have been found; indeed, some find theirexistence unlikely because of the perceived difficulty of launchingrocks at speeds above 10 km/s and traversing the planet's 93 baratmosphere. [1] Nonetheless, we keep hope alive, since cosmochemistssay they can identify Cytherean meteorites, should candidates be found[2]. Gladman et al. [3] modeled the exchange of impact ejecta betweenthe terrestrial planets, but did not consider meteorites launched fromVenus in any detail. At the time of Gladman's work, no asteroids thatremained entirely within Earth's orbit were known. 14 suchEarth-interior objects with good orbits have now been discovered, andare known as Atiras, for the Pawnee goddess of the Earth. The largestknown member of the class is 163693 Atira, a binary whose componentshave diameters of approximately 4.8 and 1 km. Discovery of Atiras isvery incomplete because they can only be seen at small solarelongations [4]. Greenstreet et al. [5] modeled the orbitaldistribution of Atiras from main-belt asteroidal and cometary sourceregions, while Ribeiro et al. [6] mapped the stability region ofhypothetical Atiras and integrated the orbits of clones of 12 realAtiras for 1 million years. 97% of the clones survived for 1 Myrimpact with Venus was the most common fate of those that met theirends. We have performed orbital integrations of 1000 clones of each ofthe known Atiras, and of hypothetical ejecta that escape Venus afterasteroid impacts, for 10-100 Myr. The latter calculations usetechniques like those of Alvarellos et al. [7] and Zahnle et al. [8]for transfer amongst Jupiter's galilean satellites. Our goals are toestimate the fraction of Atiras that are ejecta launched from Venus,the time spent in space by hypothetical meteorites from Venus, and therate at which such meteorites strike the Earth.[1] Gilmore M., et al (2017). Space Sci. Rev. 212, 1511. [2] JourdanF., Eroglu E. (2017). MAPS 52, 884. [3] Gladman B.J., etal. (1996). Science 271, 1387. [4

Ceres' intriguing Occator crater and its faculae: formation and evolution

Science.gov (United States)

Buczkowski, D.; Scully, J. E. C.; Bowling, T.; Bu, C.; Castillo, J. C.; Jaumann, R.; Longobardo, A.; Nathues, A.; Neesemann, A.; Palomba, E.; Platz, T.; Quick, L. C.; Raponi, A.; Raymond, C. A.; Ruesch, O.; Russell, C. T.; Schenk, P.; Stein, N.

2017-12-01

Since March 2015, the Dawn spacecraft has orbited and explored Ceres, which is a dwarf planet and the largest object in the asteroid belt (radius 470 km). One of the most intriguing features on Ceres' surface is Occator crater, a 92-km-diameter impact crater that contains distinctive bright spots, called faculae, within its floor (Nathues et al., 2015; Russell et al., 2016; Schenk et al., 2017). Occator crater has been dated to 20-30 million years old (Nathues et al., 2017; Neesemann et al., 2017). The single scattering albedo of Occator's faculae is 0.67-0.80, which is greater than Ceres' average single scattering albedo of 0.09-0.11 (Li et al., 2016). The central facula is named Cerealia Facula, and is located in a 9 km wide and 700 m deep pit. There are also multiple additional faculae in the eastern crater floor, which are named the Vinalia Faculae. The faculae are mostly composed of sodium carbonate, are distinct from Ceres' average surface composition and are proposed to be the solid residues of crystallized brines (De Sanctis et al., 2016). The presence of such bright, apparently fresh, material on the surface of a dwarf planet that is billions of years old is intriguing, and indicates that active processes involving brines occurred within the geologically recent past. The Dawn Science Team has investigated whether the processes that formed the crater and the faculae are entirely endogenic, entirely exogenic or a combination of both. For example, the extensive lobate materials within the crater floor have been proposed to be impact melt, mass wasting deposits or cryolava flows (e.g. Buczkowski et al., 2017; Jaumann et al., 2017; Nathues et al., 2017; Schenk et al., 2017). Each possibility has the potential to provide fascinating insights into Ceres' evolution, including the potential for liquids within Ceres' interior today. The team's in-depth investigation of Occator crater will be presented in an upcoming special issue of the journal Icarus. This special

Isotopic coherence of refractory inclusions from CV and CK meteorites: Evidence from multiple isotope systems

Science.gov (United States)

Shollenberger, Quinn R.; Borg, Lars E.; Render, Jan; Ebert, Samuel; Bischoff, Addi; Russell, Sara S.; Brennecka, Gregory A.

2018-05-01

Calcium-aluminum-rich inclusions (CAIs) are the oldest dated materials in the Solar System and numerous previous studies have revealed nucleosynthetic anomalies relative to terrestrial rock standards in many isotopic systems. However, most of the isotopic data from CAIs has been limited to the Allende meteorite and a handful of other CV3 chondrites. To better constrain the isotopic composition of the CAI-forming region, we report the first Sr, Mo, Ba, Nd, and Sm isotopic compositions of two CAIs hosted in the CK3 desert meteorites NWA 4964 and NWA 6254 along with two CAIs from the CV3 desert meteorites NWA 6619 and NWA 6991. After consideration of neutron capture processes and the effects of hot-desert weathering, the Sr, Mo, Ba, Nd, and Sm stable isotopic compositions of the samples show clearly resolvable nucleosynthetic anomalies that are in agreement with previous results from Allende and other CV meteorites. The extent of neutron capture, as manifested by shifts in the observed 149Sm-150Sm isotopic composition of the CAIs is used to estimate the neutron fluence experienced by some of these samples and ranges from 8.40 × 1013 to 2.11 × 1015 n/cm2. Overall, regardless of CAI type or host meteorite, CAIs from CV and CK chondrites have similar nucleosynthetic anomalies within analytical uncertainty. We suggest the region that CV and CK CAIs formed was largely uniform with respect to Sr, Mo, Ba, Nd, and Sm isotopes when CAIs condensed and that CAIs hosted in CV and CK meteorites are derived from the same isotopic reservoir.

Study of Meteoritic Inclusion

DEFF Research Database (Denmark)

Olsen, Mia Bjørg Stolberg

of meteorite samples that date back to the birth of the solar system. In this thesis, we have taken advantage of novel methods for the high-precision analysis of various radiogenic and stable isotope systems by plasma source and thermal ionization mass spectrometry (ICPMS and TIMS) as well as by secondary....... The manuscripts presented in this thesis have provided critical insights into the origin and distribution of short-lived radioisotopes as well as the formation and transport history of chondrules and, by extension, the precursor material to asteroidal and planetary bodies. The proposal of 26Al heterogeneity...

Experimental Simulation of Meteorite Ablation during Earth Entry Using a Plasma Wind Tunnel

Energy Technology Data Exchange (ETDEWEB)

Loehle, Stefan; Zander, Fabian; Hermann, Tobias; Eberhart, Martin; Meindl, Arne; Oefele, Rainer [High Enthalpy Flow Diagnostics Group, Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany); Vaubaillon, Jeremie; Colas, Francois [Institut de Mécanique Céleste et de Calcul des Éphémerides, Observatoire de Paris, Av. de l’Observatoire, Paris (France); Vernazza, Pierre; Drouard, Alexis [Laboratoire d’Astrophysique de Marseille, Aix Marseille Univ, CNRS, LAM, Marseille (France); Gattacceca, Jerome [CNRS, Aix-Marseille Univ, IRD, Coll France, CEREGE, Aix-en-Provence,France, Avenue Louis Philibert, 13545 Aix-en-Provence (France)

2017-03-10

Three different types of rocks were tested in a high enthalpy air plasma flow. Two terrestrial rocks, basalt and argillite, and an ordinary chondrite, with a 10 mm diameter cylindrical shape were tested in order to observe decomposition, potential fragmentation, and spectral signature. The goal was to simulate meteoroid ablation to interpret meteor observation and compare these observations with ground based measurements. The test flow with a local mass-specific enthalpy of 70 MJ kg{sup −1} results in a surface heat flux at the meteorite fragment surface of approximately 16 MW m{sup −2}. The stagnation pressure is 24 hPa, which corresponds to a flight condition in the upper atmosphere around 80 km assuming an entry velocity of 10 km s{sup −1}. Five different diagnostic methods were applied simultaneously to characterize the meteorite fragmentation and destruction in the ground test: short exposure photography, regular video, high-speed imaging with 10 kHz frame rate, thermography, and Echelle emission spectroscopy. This is the first time that comprehensive testing of various meteorite fragments under the same flow condition was conducted. The data sets indeed show typical meteorite ablation behavior. The cylindrically shaped fragments melt and evaporate within about 4 s. The spectral data allow the identification of the material from the spectra which is of particular importance for future spectroscopic meteor observations. For the tested ordinary chondrite sample a comparison to an observed meteor spectra shows good agreement. The present data show that this testing methodology reproduces the ablation phenomena of meteoritic material alongside the corresponding spectral signatures.

Turbulent flow over craters on Mars: Vorticity dynamics reveal aeolian excavation mechanism

Science.gov (United States)

Anderson, William; Day, Mackenzie

2017-10-01

Impact craters are scattered across Mars. These craters exhibit geometric self-similarity over a spectrum of diameters, ranging from tens to thousands of kilometers. The late Noachian-early Hesperian boundary marks a dramatic shift in the role of mid-latitude craters, from depocenter sedimentary basins to aeolian source areas. At present day, many craters contain prominent layered sedimentary mounds with maximum elevations comparable to the rim height. The mounds are remnants of Noachian deposition and are surrounded by a radial moat. Large-eddy simulation has been used to model turbulent flows over synthetic craterlike geometries. Geometric attributes of the craters and the aloft flow have been carefully matched to resemble ambient conditions in the atmospheric boundary layer of Mars. Vorticity dynamics analysis within the crater basin reveals the presence of counterrotating helical vortices, verifying the efficacy of deflationary models put forth recently by Bennett and Bell [K. Bennett and J. Bell, Icarus 264, 331 (2016)], 10.1016/j.icarus.2015.09.041 and Day et al. [M. Day et al., Geophys. Res. Lett. 43, 2473 (2016)], 10.1002/2016GL068011. We show how these helical counterrotating vortices spiral around the outer rim, gradually deflating the moat and carving the mound; excavation occurs faster on the upwind side, explaining the radial eccentricity of the mounds relative to the surrounding crater basin.

Turbulent flow over craters on Mars: Vorticity dynamics reveal aeolian excavation mechanism.