D. S. Lauretta

The University of Arizona, Tucson, Arizona, United States

Are you D. S. Lauretta?

Claim your profile

Publications (197)207.87 Total impact

  • Source
    Paleolimnology of Northern Eurasia, Petrozavodsk; 09/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Design Reference Asteroid (DRA) is a compilation of all that is known about the OSIRIS-REx mission target, asteroid (101955) Bennu. It contains our best knowledge of the properties of Bennu based on an extensive observational campaign that began shortly after its discovery, and has been used to inform mission plan development and flight system design. The DRA will also be compared with post-encounter science results to determine the accuracy of our Earth-based characterization efforts. The extensive observations of Bennu in 1999 has made it one of the best-characterized near-Earth asteroids. Many physical parameters are well determined, and span a number of categories: Orbital, Bulk, Rotational, Radar, Photometric, Spectroscopic, Thermal, Surface Analog, and Environment Properties. Some results described in the DRA have been published in peer-reviewed journals while others have been reviewed by OSIRIS-REx Science Team members and/or external reviewers. Some data, such as Surface Analog Properties, are based on our best knowledge of asteroid surfaces, in particular those of asteroids Eros and Itokawa. This public release of the OSIRIS-REx Design Reference Asteroid is a annotated version of the internal OSIRIS-REx document OREX-DOCS-04.00-00002, Rev 9 (accepted by the OSIRIS-REx project on 2014-April-14). The supplemental data products that accompany the official OSIRIS-REx version of the DRA are not included in this release. We are making this document available as a service to future mission planners in the hope that it will inform their efforts.
    09/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report in situ O isotope and chemical compositions of magnetite and olivine in chondrules of the carbonaceous chondrites Watson-002 (anomalous CK3) and Asuka (A)-881595 (ungrouped C3). Magnetite in Watson-002 occurs as inclusion-free subhedral grains and rounded inclusion-bearing porous grains replacing Fe,Ni-metal. In A-881595, magnetite is almost entirely inclusion-free and coexists with Ni-rich sulfide and less abundant Ni-poor metal. Oxygen isotope compositions of chondrule olivine in both meteorites plot along carbonaceous chondrite anhydrous mineral (CCAM) line with a slope of approximately 1 and show a range of Δ17O values (from approximately −3 to −6‰). One chondrule from each sample was found to contain O isotopically heterogeneous olivine, probably relict grains. Oxygen isotope compositions of magnetite in A-881595 plot along a mass-dependent fractionation line with a slope of 0.5 and show a range of Δ17O values from −2.4‰ to −1.1‰. Oxygen isotope compositions of magnetite in Watson-002 cluster near the CCAM line and a Δ17O value of −4.0‰ to −2.9‰. These observations indicate that magnetite and chondrule olivine are in O isotope disequilibrium, and, therefore, not cogenetic. We infer that magnetite in CK chondrites formed by the oxidation of pre-existing metal grains by an aqueous fluid during parent body alteration, in agreement with previous studies. The differences in Δ17O values of magnetite between Watson-002 and A-881595 can be attributed to their different thermal histories: the former experienced a higher degree of thermal metamorphism that led to the O isotope exchange between magnetite and adjacent silicates.
    Meteoritics & Planetary Science. 08/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Concentration and distribution of trace elements across the sequence of the Late Pleistocene sediments from the lake Medvedevskoye suggest the addition of materials other than those from a common source for the lake sediments of the region. The sediments of the lake Medvedevskoye carry some geochemical fingerprints which could be related the ET event that occurred at ca. 12.9 ka. Because such fingerprints are extremely subtle, the NW Russia can be considered to be the most remote eastern region of the extent of the Late Pleistocene airborne ET material. The sediments of the lake Medvedevskoye can also contain volcanic material from the eruption of the Laacher See (Germany) volcano and probably from other Late Pleistocene volcanoes of Western Europe and/or Iceland.
    Doklady Earth Sciences 07/2014; 457(1):819-823. · 0.39 Impact Factor
  • Source
    Asteroids, Comets, Meteors 2014, Helsinki, Finland; 06/2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Near-Earth Asteroids (NEAs) have garnered ever increasing attention over the past few years due to the insights they offer into Solar System formation and evolution, the potential hazard they pose, and their accessibility for both robotic and human spaceflight missions. Among the NEAs, carbonaceous asteroids hold particular interest because they may contain clues to how the Earth got its supplies of water and organic materials, and because none has yet been studied in detail by spacecraft. (101955) Bennu is special among NEAs in that it will not only be visited by a spacecraft, but the OSIRIS-REx mission will also return a sample of Bennu’s regolith to Earth for detailed laboratory study. This paper presents analysis of thermal infrared photometry and spectroscopy that test the hypotheses that Bennu is carbonaceous and that its surface is covered in fine-grained (sub-cm) regolith. The Spitzer Space Telescope observed Bennu in 2007, using the Infrared Spectrograph (IRS) to obtain spectra over the wavelength range 5.2–38 μm and images at 16 and 22 μm at 10 different longitudes, as well as the Infrared Array Camera (IRAC) to image Bennu at 3.6, 4.5, 5.8, and 8.0 μm, also at 10 different longitudes. Thermophysical analysis, assuming a spherical body with the known rotation period and spin-pole orientation, returns an effective diameter of 484 ± 10 m, in agreement with the effective diameter calculated from the radar shape model at the orientation of the Spitzer observations (492 ± 20 m, Nolan, M.C., Magri, C., Howell, E.S., Benner, L.A.M., Giorgini, J.D., Hergenrother, C.W., Hudson, R.S., Lauretta, D.S., Margo, J.-L., Ostro, S.J., Scheeres, D.J. [2013]. Icarus 226, 629–640) and a visible geometric albedo of 0.046 ± 0.005 (using Hv = 20.51, Hergenrother, C.W. et al. [2013]. Icarus 226, 663–670). Including the radar shape model in the thermal analysis, and taking surface roughness into account, yields a disk-averaged thermal inertia of 310 ± 70 J m−2 K−1 s−1/2, which is significantly lower than several other NEAs of comparable size. There may be a small variation of thermal inertia with rotational phase (±60 J m−2 K−1 s−1/2). The spectral analysis is inconclusive in terms of surface mineralogy; the emissivity spectra have a relatively low signal-to-noise ratio and no spectral features are detected. The thermal inertia indicates average regolith grain size on the scale of several millimeters to about a centimeter. This moderate grain size is also consistent with low spectral contrast in the 7.5–20 μm spectral range. If real, the rotational variation in thermal inertia would be consistent with a change in average grain size of only about a millimeter. The thermophysical properties of Bennu’s surface appear to be fairly homogeneous longitudinally. A search for a dust coma failed to detect any extended emission, putting an upper limit of about 106 g of dust within 4750 km of Bennu. Three common methodologies for thermal modeling are compared, and some issues to be aware of when interpreting the results of such models are discussed. We predict that the OSIRIS-REx spacecraft will find a low albedo surface with abundant sub-cm sized grains, fairly evenly distributed in longitude.
    Icarus 05/2014; 234:17–35. · 3.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An environmental simulation chamber was used to measure the emissivities of a selection of ground meteorites under isothermal and asteroid-like conditions.
    02/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: NASA's OSIRIS-REx mission will return samples of asteroid Bennu in 2023. We review our approach to unraveling the history of Bennu by returned sample analyses.
    02/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although rare in meteorites, chalcopyrite (CuFeS2) is seen in R chondrites. Thermodynamics predict it formed in aqueous conditions or by melt crystallization.
    02/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The target asteroid of the OSIRIS-REx asteroid sample return mission, (101955) Bennu (formerly 1999 RQ$_{36}$), is a half-kilometer near-Earth asteroid with an extraordinarily well constrained orbit. An extensive data set of optical astrometry from 1999--2013 and high-quality radar delay measurements to Bennu in 1999, 2005, and 2011 reveal the action of the Yarkovsky effect, with a mean semimajor axis drift rate $da/dt = (-19.0 \pm 0.1)\times 10^{-4}$ au/Myr or $284\pm 1.5\;\rm{m/yr}$. The accuracy of this result depends critically on the fidelity of the observational and dynamical model. As an example, neglecting the relativistic perturbations of the Earth during close approaches affects the orbit with $3\sigma$ significance in $da/dt$. The orbital deviations from purely gravitational dynamics allow us to deduce the acceleration of the Yarkovsky effect, while the known physical characterization of Bennu allows us to independently model the force due to thermal emissions. The combination of these two analyses yields a bulk density of $\rho = 1260\pm70\,\rm{kg/m^3}$, which indicates a macroporosity in the range $40\pm10$% for the bulk densities of likely analog meteorites, suggesting a rubble-pile internal structure. The associated mass estimate is $(7.8\pm0.9)\times 10^{10}\, \rm{kg}$ and $GM = 5.2\pm0.6\,\rm{m^3/s^2}$. Bennu's Earth close approaches are deterministic over the interval 1654--2135, beyond which the predictions are statistical in nature. In particular, the 2135 close approach is likely within the lunar distance and leads to strong scattering and therefore numerous potential impacts in subsequent years, from 2175--2196. The highest individual impact probability is $9.5\times 10^{-5}$ in 2196, and the cumulative impact probability is $3.7\times 10^{-4}$, leading to a cumulative Palermo Scale of -1.70.
    Icarus. 02/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A fragment of the Chelyabinsk meteorite (LL5, S4, WG0) represented by an impact melt breccia is studied for chemical composition of metals and sulfides.
    01/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The primitive achondrites provide a window into the initial melting of asteroids in the early solar system. The brachinites are olivine-dominated meteorites with a recrystallized texture that we and others interpret as evidence of partial melting and melt removal on the brachinite parent body. We present a petrologic, thermodynamic and experimental study of the brachinites to evaluate the conditions under which they formed and test our hypothesis that the precursor material to the brachinites was FeO-rich compared to the precursors of other primitive achondrites. Petrologic analysis of six brachinites (Brachina, Allan Hills (ALH) 84025, Hughes 026, Elephant Moraine (EET) 99402, Northwest Africa (NWA) 3151, and NWA 4969) and one brachinite-like achondrite (NWA 5400) shows that they are meteorites with recrystallized texture that are enriched in olivine (⩾80 vol.%) and depleted in other minerals with respect to a chondritic mineralogy. Silicates in the brachinites are FeO-rich (Fa32–36). Brachinite-like achondrite Northwest Africa 5400 is similar in mineralogy and texture to the brachinites but with a slightly lower FeO-content (Fa30). Thermodynamic calculations yield equilibration temperatures above the Fe,Ni–FeS cotectic temperature (˜950 °C) for all meteorites studied here and temperatures above the silicate eutectic (˜1050 °C) for all but two. Brachina formed at an fO2 of ˜IW, and the other brachinites and NWA 5400 formed at ˜IW ‑ 1. All the meteorites show great evidence of formation by partial melting having approximately chondritic to depleted chondritic mineralogies, equilibrated mineral compositions, and recrystallized textures, and having reached temperatures above that required for melt generation. In an attempt to simulate the formation of the brachinite meteorites, we performed one-atmosphere, gas-mixing partial melting experiments of R4 chondrite LaPaz Ice Field 03639. Experiments at 1250 °C and an oxygen fugacity of IW ‑ 1 produce residual phases that are within the mineralogy and mineral compositions of the brachinites. These experiments provide further evidence for the formation of brachinites as a result of partial melting of a chondritic precursor similar in mineralogy and mineral compositions to the R chondrites.
    Geochimica et Cosmochimica Acta 12/2013; · 3.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present the three-dimensional shape of near-Earth asteroid (101955) Bennu (provisional designation 1999 RQ36) based on radar images and optical lightcurves (Nolan et al., 2013). Bennu was observed both in 1999 at its discovery apparition, and in 2005 using the 12.6-cm radar at the Arecibo Observatory and the 3.5-cm radar at the Goldstone tracking station. Data obtained in both apparitions were used to construct a shape model of this object. Observations were also obtained at many other wavelengths to characterize this object, some of which were used to further constrain the shape modeling (Clark et al., 2011; Hergenrother et al., 2013; Krugly et al., 1999).
    NASA Planetary Data System. 09/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We determine the three-dimensional shape of near-Earth Asteroid (101955) Bennu based on radar images and optical lightcurves. Bennu was observed both in 1999 at its discovery apparition, and in 2005 using the 12.6-cm radar at the Arecibo Observatory and the 3.5-cm radar at the Goldstone tracking station. Data obtained in both apparitions were used to construct a shape model of this object. Observations were also obtained at many other wavelengths to characterize this object, some of which were used to further constrain the shape modeling. The lightcurve data, along with an initial determination of the rotation period derived from them, simplified and improved the shape modeling.
    Icarus 09/2013; 226(1):629-640. · 3.16 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: IN SEARCH FOR FINGERPRINTS OF A POSSIBLE ET IMPACT: HR-ICP-MS STUDY OF LATE PLEISTOCENE LAKE SEDIMENTS OF LITHUANIA Alexandre V. Andronikov, Eugenija Rudnickaitė, Dante S. Lauretta, Irina E. Andronikova, Donatas Kaminskas, Petras Šinkūnas, Monika Melešytė Climate oscillation in the Northern Hemisphere (the Younger Dryas; YD) which occurred between ca. 12.9K cal yr BP and ca. 11.7K cal yr BP (Peteet, 1995; Alley, 2000; Björck, 2007; Lowe et al., 2008; Murton et al., 2010) is connected predominantly to a sharp decrease of thermohaline circulation in the Atlantic Ocean triggered by a sudden fresh-water release to the North Atlantic (Murton et al., 2010; Teller et al., 2002; McManus et al., 2004). Recently, a team of scientists proposed a new hypothesis relating the YD cooling to an extraterrestrial (ET) body impact (Firestone et al., 2007). This hypothesis suggested that just before the onset of the YD cooling (ca. 12.9K cal yr BP), a large bolide exploded over the N. American Laurentide Ice Sheet, and the consequences of such a catastrophic event (“meteorite impact winter”) led to the abrupt and significant climate alteration. In Europe, studies of the YD impact hypothesis are limited. However, some findings could be in favor of the ET hypothesis. Those include the presence of an Ir anomaly in the Bodmin Moor sediments from the LYDB in SW England (Marshall et al., 2011), the discovery of non-radiogenic possibly ET-related 187Os/188Os ratios in a sedimentary layer dated 12,893±75 cal yr BP in the S. Netherlands (Beets et al., 2008), and the presence of geochemical markers related to the ET impact in the Late-Glacial lake sediments of NW Russia (Andronikov et al., 2012). Nanodiamonds found in the Usselo Horizon of Belgium and the Netherlands (Tian et al., 2010; van Hoesel et al., 2012) are controversial in terms of their ET origin, and the authors of these papers consider them to be of terrestrial origin, but they are still nanodiamonds and are identified along the LYDB. When a large ET object hits the Earth, small particles resulted from the impact (both from the impactor and from the targeted material) can travel in the atmosphere for thousands of kilometers before they finally get deposited (Bunch et al., 2008; Artemieva and Morgan, 2011). If the impact occurred over N. America, the dominating west winds (Isarin and Renssen, 1999; Brauer et al., 2008) could have delivered the impact-related microparticles as far east as Europe. Lithuania could be an important place in determining the eastern boundary of the Late Pleistocene ET material occurrence. We are applying here geochemical analyses of sediments across four Late-Glacial lake sequences from Lithuania in order to decipher the trace element distribution. This way, the presence of anomalous (in particular, ET-related) components in the sediments can be detected. Concentrations of trace elements in Late- Glacial lakes sediments from four sites in Lithuania were studied using HR-ICP-MS. Most studied sequences are lithologically inhomogeneous and are characterized by uneven distribution of trace elements across the sequences. In some cases the changes in geochemical characteristics are due to changes in lithology and conditions of sediment deposition. However, a few features are not consistent with a sheer lithology change and require other explanations. We were able, with a high level of confidence, to reveal in all four studied sedimentary sequences geochemical fingerprints of the ET event, which occurred at ca. 11.7K cal yr BP. Since there are no known meteorite craters of this age in the region, this event was pronounced, most likely, as an aerial explosion (unless the impact occurred to the continental Ice Sheet). Elevated concentrations of Ni, Cr and somewhat PGE in sediments of this age could be used as a geochemical stratigraphic marker. The presence of possible ET material was also detected for the Ula-2 sequence at the stratigraphic level corresponding to the age of ca. 13.0K cal yr BP, on the basis of sharply increasing concentrations of Ni, Cr, and elevated concentrations of the PGE. In addition to the presence of the ET material in the studied sediments, such geochemical features as elevated concentrations of the REE, Zr and Hf (i.e., the elements abundant in products of the volcanic eruptions) of the sediments from the Ula-2 site allowed us to suggest a presence of volcanic material likely related to the eruption of the Laacher See volcano (12,880 cal yr BP; Brauer et al., 1999). A proposed scheme of the distribution of the ET-related material over the Northern Hemisphere suggests that the consequences of the Late Pleistocene impact/explosion would strongly affect North America, but the rest of the world would be affected by much smaller extent. The applied geochemical methodology, if confirmed by further research on additional sequences, could potentially be used as a tool for correlation between different Late-Glacial records in order to obtain better chronologies for a period during which radiocarbon dating still contains uncertainties. In addition to the presence of the ET material in the studied sediments, such geochemical features as elevated concentrations of the REE, Zr and Hf (i.e., the elements abundant in products of the volcanic eruptions) of the sediments from the Ula-2 site allowed us to suggest a presence of volcanic material likely related to the eruption of the Laacher See volcano (12,880 cal yr BP; Brauer et al., 1999). A proposed scheme of the distribution of the ET-related material over the Northern Hemisphere suggests that the consequences of the Late Pleistocene impact/explosion would strongly affect North America, but the rest of the world would be affected by much smaller extent. The applied geochemical methodology, if confirmed by further research on additional sequences, could potentially be used as a tool for correlation between different Late-Glacial records in order to obtain better chronologies for a period during which radiocarbon dating still contains uncertainties. Acknowledgements. Authors thank C.V.Haynes, J.Ballenger, A. van Hoesel, W.Hoek, M.Drury, D.A.Subetto, T.V.Sapelko, and N.Artemieva for very fruitful discussions on the considered issues. This study was supported partly by the NAI International Collaboration Fund for AVA. Field work was financed by the Research Council of Lithuania, project № LEK-03/2010. References Alley R.B. (2000) The Younger Dryas cold interval as viewed from central Greenland. Quater Sc Rev 19:213-226. Andronikov A., et al. (2012) Tale of two lakes: HR-ICP-MS study of Late Glacial sediments from the Snellegem pond in Belgium and Lake Medvedevskoye in NW Russia. Abst Int Conf “Geomorphology and Quaternary Paleogeography of Polar Regions”, St. Petersburg, Herzen Pedagogical University Press. Artemieva N., Morgan J. (2011) Modeling the Formation of the Global K/Pg Layer. Abst 74th Ann Meteor Soc Palaeolandscapes from Saalian to Weichselian, South Eastern Lithuania Meeting, Abst 5065. Beets C., et al. (2008) Search for extraterrestrial osmium at the Allerod – Younger Dryas Boundary. Amer Geophys Union, Fall Meeting 2008, Abst V53A-2150. Björck S. (2007) Younger Dryas Oscillation, Global Evidence. In: Scott A.E. (ed.) Encyclopedia of Quaternary Sci. Oxford, Elsevier, 1983-1995. Brauer A., et al. (1999) Lateglacial calendar year chronology based on annually laminated sediments from Lake Meerfelder Maar, Germany. Quaternary Intl 61:17-25. Bunch T.E., et al. (2008) Hexagonal diamonds (lonsdaleite) discovered in the K/T impact layer in Spain and New Zealand. AGU Fall Meeting, Abstract PP13C-1476, Eos Trans 89. Fayek M., et al. (2012) Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona. Earth Planet Sci Lett 319-320:251-258. Firestone R.B., et al. (2007) Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions at the Younger Dryas cooling. Proc Natl Acad Sci 104:16016-16021. Higgins M.D., et al. (2011) Bathymetric and petrological evidence for a young (Pleistocene?) 4-km diameter impact crater in the Gulf of Saint Lawrence, Canada. 42nd Lunar Planet Sci Conf 1504-1505. van Hoesel A, et al. (2012) Nanodiamonds and wildfire evidence in the Usselo horizon postdate the Allerød- Younger Dryas boundary. Proc Natl Acad Sci 109:7648-7653. Isarin R.F.B., Renssen H. (1999) Reconstructing and modeling Late Weichselian climates: the Younger Dryas in Europe as a case study. Earth-Sci Rev 48:1-38. Israde-Alcántara I., et al. (2012) Evidence from Central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis. Proc Natl Acad Sci 109:E738-E747. Kennett D.J., et al. (2009) Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments. Proc Natl Acad Sci 106:12623-12628. Kurbatov A.V., et al. (2010) Discovery of Nanodiamond-rich Layer in Polar Ice Sheet (Greenland). J Glaciol 56:749-759. Lowe J.J., et al. (2008) Synchronisation of palaeoenvironmental events in the North Atlantic region during the Last Termination: a revised protocol recommended by the INTIMATE group. Quaternary Sci Rev 27:6-17. McManus J.F., et al. (2004) Collapse and rapid resumption of Atlantic meridianal circulation linked to deglacial climate changes. Nature 428:834-837. Mahaney W.C., et al. (2010) Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: The black mat enigma. Geomorphology 116:48-57. Marshall W., et al. (2011) Exceptional iridium concentrations found at the Allerød-Younger Dryas transition in sediments from Bodmin Moor in southwest England. Abst XVIII INQUA Congress 21-27 July 2011 Bern, Switzerland (ID 2641). Murton J.B., et al. (2010) Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean. Nature 464:740-743. Peteet D. (1995) Global Younger Dryas? Quaternary Intl 28: 93-104. Sharma M., et al. (2009) High resolution Osmium isotopes in deep-sea ferromanganese crusts reveal a large meteorite impact in the Central Pacific at 12±4 ka. Eos Trans AGU 90, Fall Meeting Suppl, Abst PP33B-06. Svendsen J., et al. (2004) Late Quaternary ice sheet history of Eurasia. Quaternary Sci Rev. Doi:10.1016/ j.quascirev.2003.12.008. Teller J.T., et al. (2002) Freshwater outbursts to the ocean from glacial Lake Agassiz and their role in climate change during the last deglaciation. Quaternary Sci Rev 21:879-887. Thomson J. (1995) Ice age terrestrial carbon change revised. Glob Geochem Cycles 9:377-389. Tian H., et al. (2010) Nanodiamonds do not provide unique evidence for a Younger Dryas impact. Proc Natl Acad Sci Hwww.pnas.org/cgi/doi/10.1073/pnas. 1007695108H.
    Palaeolandscapes from Saalian to Weichselian, South Eastern Lithuania. International Field Symposium. June 25 – 30, 2013, Vilnius-Trakai, Lithuania, Vilnius-Trakai, Lithuania; 06/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The NASA OSIRIS-REx mission will retrieve a sample of the carbonaceous near-Earth Asteroid (101955) Bennu and return it to Earth in 2023. Photometry in the Eight Color Asteroid Survey (ECAS) filter system and Johnson–Cousins V and R filters were conducted during the two most recent apparitions in 2005/2006 and 2011/2012. Lightcurve observations over the nights of September 14–17, 2005 yielded a synodic rotation period of 4.2905 ± 0.0065 h,which is consistent with the results of Nolan et al. (2013). ECAS color measurements made during the same nights confirm the B-type classification of Clark et al. (Clark, B.E., Binzel, R.P., Howell, E.S., Cloutis, E.A., Ockert-Bell, M., Christensen, P., Barucci, M.A., DeMeo, F., Lauretta, D.S., Connolly, H., Soderberg, A.,Hergenrother, C., Lim, L.,Emery, J.,Mueller,M. [2011]. Icarus 216, 462–475).A search for the 0.7 microns hydration feature using themethod of Vilas (Vilas, F. [1994]. Icarus 111, 456–467) did not reveal its presence. Photometry was obtained over a range of phase angles from 15 to 96 degrees between 2005 and 2012. The resulting phase function slope of 0.040 magnitudes per degree is consistent with the phase slopes of other low albedo near-Earth asteroids (Belskaya, I.N., Shevchenko, V.G. [2000]. Icarus 147, 94–105).
    Icarus 05/2013; 226:663-670. · 3.16 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The so-called Nysa-Polana complex of asteroids is a diverse and widespread group. It appears to be two overlapping families of different asteroid taxonomies: (44) Nysa is an E-type asteroid with the lowest number in the midst of a predominantly S-type cluster and (142) Polana is a B-type asteroid near the low-albedo B- and C-type cluster. Using the data from the Wide-field Infrared Survey Explorer (WISE) mission we have re-analyzed the region around the Nysa-Polana complex in the inner Main Belt, focusing on the low-albedo population. (142) Polana does not appear to be a member of the family of low-albedo asteroids in the Nysa-Polana complex. Rather, the largest is asteroid (495) Eulalia. This asteroid has never before been linked to this complex for an important dynamical reason: it currently has a proper eccentricity slightly below the range of most of the family members. However, its orbit is very close to the 3:1 mean motion resonance with Jupiter and is in a weak secular resonance. We show that its osculating eccentricity varies widely on short timescales and the averaged value diffuses over long timescales. The diffusive orbit, low-albedo, taxonomic similarity and semimajor axis strongly suggests that despite its current proper eccentricity, (495) Eulalia could have recently been at an orbit very central to the family. Hierarchical Clustering Method tests confirm that at an eccentricity of e=0.15, (495) Eulalia could be the parent of the family. The ``Eulalia family'' was formed between 900--1500 Myr ago, and likely resulted from the breakup of a 100--160 km parent body. There is also compelling evidence for an older and more widespread primitive family in the same region of the asteroid belt parented by asteroid (142) Polana.
    Icarus 05/2013; 225(1). · 3.16 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present results of LA-ICP-MS analyses of pellets prepared from EOC for the OSIRIS-REx program. Various reference materials were used for comparison.
    03/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: OSIRIS-REx's "Target Asteroids!" is a citizen science program for amateur astronomers that contributes to basic scientific understanding of near-Earth objects.
    03/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We discuss the microstructures and textures of sulfide grains from Alais and Orgueil and the implications that these data have on grain formation conditions.
    03/2013;

Publication Stats

726 Citations
207.87 Total Impact Points

Institutions

  • 2002–2014
    • The University of Arizona
      • • Department of Planetary Sciences
      • • Southwest Center
      Tucson, Arizona, United States
  • 1999–2012
    • Arizona State University
      • Department of Chemistry and Biochemistry
      Mesa, AZ, United States
  • 2006
    • Sierra Tucson
      Tucson, Arizona, United States
  • 2005
    • NASA
      Washington, West Virginia, United States