Kearsley, AT; Colaux, JL; Wozniakiewicz, PJ; Gerlach, L; Anz-Meador, P; Liou, JC; Griffin, T; Reed, B; Opiela, J; Palitsin, VV; et al. (2018-04)
      HYPERVELOCITY IMPACT IN LOW EARTH ORBIT: FINDING SUBTLE IMPACTOR SIGNATURES ON THE HUBBLE SPACE TELESCOPE A T Kearsley 1,2,5, J L Colaux 3, D K Ross 4, P J Wozniakiewicz 2,5, L Gerlach 6, P Anz-Meador 4, J-C Liou 7, T Griffin 8, B Reed 8, J Opiela 4, V V Palitsin 3, G W Grime 3, R P Webb 3, C Jeynes 3, J Spratt 2, M J Cole 5, M C Price 5 and M J Burchell 5. 1 Dunholme, Raven Hall Road, Ravenscar, YO13 0NA, UK (kearsleys@runbox.com); 2 Natural History Museum (NHM), Cromwell Road, London, UK. 3 Ion Beam Centre, University of Surrey, Guildford, UK. 4 ESCG-Jacobs, NASA-JSC, Houston, TX, USA. 5 School of Physical Sciences, University of Kent, Canterbury, Kent, UK. 6 European Space Agency (ESA, retired), Noordwijk, The Netherlands. 7 NASA Johnson Space Center, Houston, TX, USA. 8 NASA Goddard Space Flight Center (GSFC), Greenbelt, Maryland, USA. ABSTRACT Introduction Return of large surface area components from the Hubble Space Telescope (HST) during shuttle orbiter service missions has allowed inspection of large numbers of hyper-velocity impact features from long exposure in low Earth orbit (LEO). Particular attention has been paid to the origin of the impacting particles, whether artificial Orbital Debris (OD) or natural Micrometeoroid (MM). Extensive studies have been made of solar cells (Graham et al., 2001; Kearsley et al 2005, Moussi et al., 2005) and recently, the painted metal surface of the Wide Field and Planetary Camera 2 WFPC2 radiator shield (Anz-Meador et al., 2013; Colaux et al., 2014; Kearsley et al., 2014a; Ross et al., 2014). Both of these materials from HST have layers of complex chemical composition, into which particle fragments and melt may infiltrate during impact. Experimental light gas gun (LGG) impacts (e.g. Price et al., 2014) have shown that impactor remains may be dispersed and dilute, often as a very thin and patchy coating within an irregular impact-generated pit. In previous studies, the low concentration of particle residue, the rugged topography of impact features, and especially the complex multi-element composition of the impacted surface were considered significant barriers to recognition of extraneous impactor-derived components. Analysis was both difficult and time consuming (e.g. Graham et al., 2001), and a substantial proportion of impactors (25-65%) could not be identified. Recent advances in energy dispersive X-ray microanalysis (EDX) now permit routine identification of impactor origins using scanning electron microscope (SEM); particle induced X-ray emission (PIXE) and micro-X-ray fluorescence (µ-XRF) instruments (Kearsley et al., 2012, 2014b). Here we demonstrate how these techniques have allowed impactor composition to be isolated, and the particle source determined for the great majority of WFPC2 samples studied. Methods To analyse impact melt on the zinc orthotitanate (ZOT) and aluminium alloy (Al-6061) of the WFPC2 radiator shield we used the Oxford Instruments INCA SEM-EDX spectrum pro-cessing software to separate peak and background X-ray counts for specified X-ray emission lines. From tables of likely OD and MM signature elements (e.g. Kearsley et al., 2005), and knowledge of the pristine WFPC paint and alloy compositions, we extracted data for the fol-lowing elements: Mg, Al, Si, S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu and Zn. Two types of graphical plot were developed, to highlight extraneous element signatures in small impacts on the ZOT paint (Fig. 1), and larger craters into the Al-alloy (Fig. 2). The impactor origin was then clas-sified by reference to a suite of decision trees (Kearsley et al., 2012). A Bruker X-Flash 6050 EDX detector was also used to obtain signal from the interior of deeper craters. PIXE maps and spectra were acquired in the Ion Beam Centre, University of Surrey (Colaux et al., 2014). Results Figure 1. WFPC2 impact feature 339: a) SEM backscattered electron (BE) image; b) SEM depth model; c) SEM-EDX maps show high Mg concentration in the impact melt lining the impact feature d) plots of SEM-EDX X-ray counts for Mg and Fe show much higher levels in impact melt (red) than in clean ZOT paint (blue), and a similar level to impact residue from LGG impacts of olivine grains (open black squares). Excess Mg and Fe contents in frothy impact melt show impactor was a micrometeoroid. Figure 2). WFPC2 impact feature 462: a) SEM BE image; b) SEM depth profile; c and d) PIXE EDX maps show Fe and Ni across crater pit and surrounding metal, some iron-rich in-clusions in the Al alloy, but Ni only enriched in pit; e) PIXE EDX spectra show high Fe and Ni on crater floor, similar to micrometeoroid metal composition; f) plot of Mg/Al versus Cr/Fe X-ray counts in SEM-EDX spectra from the crater edge (red) show enrichment of Mg and Fe over alloy composition (black, grey, yellow and green), indicating a mafic silicate mi-crometeoroid component has also been added from the impacted micrometeoroid. Summary and conclusions Together, SEM-EDX and PIXE-EDX maps, spectra and X-ray count plots showed 166 MM residues and 2 OD residues in this survey of 188 impact features on WFPC2, ~ 90% of those examined, considerable enhancement of impactor recognition over an earlier study of HST impacts (~75% identified as MM or OD in origin, Kearsley et al., 2005). Acknowledgements ESA contract 40001105713/12/NL/GE awarded to NHM and the University of Surrey; Bruker for expertise in use of the X-Flash detector and loan of the M4 Tornado µ-XRF. References quoted Anz-Meador P. et al. (2013) Proc. 6th European Conf. Space Debris, ESA SP 723: s1b_anzme.pdf, CD-ROM. Colaux J. L. et al. (2014) LPSC 45 Abstract #1727. Graham, G.A. et al. (2001) Proc. 3rd European Conf. Space Debris, ESA SP 473:197–203. Kearsley A.T. et al., (2005) Adv. Space Res. 35:1254–1262. Kearsley A. T. et al. (2012) Technical Note 1 for ESA contract 40001105713/12/NL/GE. Kearsley A. T. et al. (2014a) LPSC 45 abstract #1722. Kearsley A.T. et al. (2014b) LPSC 45 abstract #1733. Moussi A. et al. (2005) Adv. Space Res. 35:1243–1253. Price M. C. et al. (2014) LPSC 45 abstract #1466. Ross D. K. et al. (2014) LPSC 45 abstract #1514.
    • The remedial conservation and support jacketing of the Massospondylus carinatus neotype

      Graham, M; Choiniere, JN; Jirah, S; Barrett, PM (Palaeontologia africana, 2018-03-27)
      Massopondylus carinatus Owen, 1854 is a non-sauropodan sauropodomorph (‘prosauropod’) dinosaur whose remains are abundant in the Upper Karoo Supergroup sediments of southern Africa (e.g. Owen, 1854; Seeley, 1895; Cooper, 1981; Gow, 1990; Gow et al., 1990; Sues et al., 2004; Barrett and Yates, 2006; Reisz et al., 2005). It occurs at numerous localities in the Upper Elliot and Clarens formations of South Africa and Lesotho, as well as in the Forest Sandstone Formation of Zimbabwe (Haughton, 1924; Cooper, 1981; Kitching and Raath, 1984). Several almost complete skeletons are known, including skulls, and as a result Massospondylus has featured heavily in discussions of early dinosaur ecology, phylogeny and palaeobiology (e.g. Cooper, 1981; Barrett, 2000; Zelenitsky and Modesto, 2002; Reisz et al., 2005, 2012, Apaldetti et al., 2011, among many others). However, the original syntype series of Massospondylus carinatus was destroyed during World War II and shown to be taxonomically indeterminate, undermining the nomenclatural stability of this important taxon (Sues et al. 2004; Yates and Barrett, 2010). In order to rectify this problem, a complete skeleton representing an adult individual, BP/1/4934 (nicknamed ‘Big Momma’), was designated as the neotype (Yates and Barrett, 2010). BP/1/4934 was collected from the Upper Elliot Formation of Bormansdrift Farm, in the Clocholan District of the Free State, by Lucas Huma and James Kitching in 1980 (see Kitching and Raath, 1984, for locality details). This farm is also the type locality of the early turtle Australochelys (Gaffney and Kitching, 1994) and has yielded other Upper Elliot formation tetrapod material including the cynodont Pachygenelus and other sauropodomorph remains (Kitching and Raath, 1984). BP/1/4934 is the most complete specimen of a non-sauropodan sauropodomorph dinosaur known from the entire African continent and is therefore of major regional and international significance. In addition, since 1990 it has formed part of a permanent public exhibit showcasing African palaeontological discoveries in the J. W. Kitching Gallery of the Evolutionary Studies Institute (ESI) of the University of the Witwatersrand. During recent research work on BP/1/4934, as part of an on-going collaboration on early dinosaurs between the ESI and Natural History Museum, London (NHMUK), it was noted that its condition had deteriorated and that urgent remedial conservation work was required in order to preserve it for future generations. As a result, the specimen was temporarily removed from public display to facilitate this work, which is described in detail below (see also Graham, 2017). The primary purpose of the conservation project was to assess the condition of the specimen, undertake conservation in order to stabilise it and to manufacture ‘clam-shell’ type support mounts/jackets for each of the blocks to enable the specimen to be displayed in an articulated posture within a purpose-built display case. An important consideration was that the blocks should be readily accessible from both left and right sides to researchers whilst securing the fossil safely. Finally, this project also provided an opportunity to facilitate knowledge exchange between the conservation staff at the ESI and NHMUK, in order to share and extend technical expertise.
    • The origin of secondary heavy rare earth element enrichment in carbonatites: Constraints from the evolution of the Huanglongpu district, China

      Smith, M; Kynicky, J; Chen, X; Wenlei, S; Spratt, J; Jeffries, T; Brnicky, M; Kopriva, A; Cangeloosi, D (2018-03-04)
    • Mastodon and on and on…a moving story

      Allington-Jones, L (NatSCA, 2018-02-01)
      This is the latest chapter in the history of the mastodon (Mammut americanum (Kerr, 1792)) specimen on display at the Natural History Museum (NHM) in London (UK), and continues from the story told by Lindsay (1991). The specimen was selected to be one of the new exhibits for the Wonder Bays of the refurbished Hintze Hall, at the heart of the Waterhouse building. Residing, until recently, on open display in a different exhibition space, the mastodon required stabilisation and careful dismantling before transportation and reassembly in its new site.
    • The crystal structure of cesbronite, Cu 3 TeO 4 (OH) 4 : a novel sheet tellurate topology

      Missen, OP; Mills, SJ; Welch, MD; Spratt, J; Rumsey, MS; Birch, WD; Brugger, J (International Union of Crystallography, 2018-01-09)
      The crystal structure of cesbronite has been determined using single-crystal X-ray diffraction and supported by electron-microprobe analysis, powder diffraction and Raman spectroscopy. Cesbronite is orthorhombic, space group Cmcm, with a = 2.93172 (16), b = 11.8414 (6), c = 8.6047 (4) Å and V = 298.72 (3) Å3. The chemical formula of cesbronite has been revised to CuII3TeVIO4(OH)4 from CuII5(TeIVO3)2(OH)6·2H2O. This change has been accepted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, Proposal 17-C. The previously reported oxidation state of tellurium has been shown to be incorrect; the crystal structure, bond valence studies and charge balance clearly show tellurium to be hexavalent. The crystal structure of cesbronite is formed from corrugated sheets of edge-sharing CuO6 and (Cu0.5Te0.5)O6 octahedra. The structure determined here is an average structure that has underlying ordering of Cu and Te at one of the two metal sites, designated as M, which has an occupancy Cu0.5Te0.5. This averaging probably arises from an absence of correlation between adjacent polyhedral sheets, as there are two different hydrogen-bonding configurations linking sheets that are related by a ½a offset. Randomised stacking of these two configurations results in the superposition of Cu and Te and leads to the Cu0.5Te0.5 occupancy of the M site in the average structure. Bond-valence analysis is used to choose the most probable Cu/Te ordering scheme and also to identify protonation sites (OH). The chosen ordering scheme and its associated OH sites are shown to be consistent with the revised chemical formula.
    • Impact vaporization and Condensation: Laser Irradiation Experiments with Natural Planetary Materials

      Hamann, C; Hecht, L; Schäffer, S; Heunoske, D; Salge, T; Garbout, A; Osterholz, J; Greshake, A (The Woodlands, Texas, USA, 2018)
    • Identification of fossil worm tubes from Phanerozoic hydrothermal vents and cold seeps

      Georgieva, MN; Little, CTS; Watson, JS; Sephton, MA; Ball, AD; Glover, AG (2017-12-28)
    • Siidraite, Pb 2 Cu(OH) 2 I 3 , from Broken Hill, New South Wales, Australia: the third halocuprate(I) mineral

      Rumsey, MS; Welch, MD; Kleppe, AK; Spratt, J (E. Schweizerbart’sche Verlagsbuchhandlung, 2017-12-01)
      Siidraite, Pb2Cu(OH)2I3, is a new mineral from the Broken Hill deposit in New South Wales, Australia. It occurs as an extremely rare secondary phase alongside marshite, other lead and copper secondaries and supergene cuprite on a single specimen, BM 84642 preserved in the collection of the Natural History Museum, London. Siidraite is yellow and occurs in crystalline grainy aggregates up to 0.3 mm around relict galena. The mineral is translucent with a vitreous lustre and yellow streak, no cleavages or forms have yet been observed. It is non-fluorescent in mixed-wavelength UV light. The calculated density is 6.505 g cm−3. Siidraite is orthorhombic, space group Fddd, a = 16.7082(9) Å, b = 20.846(1) Å, c = 21.016(1) Å, V = 7320.0(8) Å3 and Z = 32. The empirical formula derived from a combination of electron-microprobe analysis and structure determination is Pb2.06Cu0.89(OH)2I2.97, the ideal formula has (in wt%) 8.01 Cu2O, 50.01 PbO, 42.65 I and 2.02 H2O. The five strongest lines in the calculated X-ray powder diffraction pattern are [(h k l), d obs (Å), I/I max (%)]: [(2 4 6), 2.746, 100], [(4 0 4), 3.270, 81], [(2 6 4), 2.738, 77], [(3 1 5), 3.312, 76], [(3 5 1), 3.296, 69]. The crystal used for structure determination had minor pseudomerohedral twinning on [ 0   1 ‾   1 ] and the structure was refined taking this into account to R 1 = 0.037, wR 2 = 0.052, GooF = 1.016, based upon 1368 unique reflections having I > 2σ(I). The structure of siidraite is a framework comprising an alternation of two structural elements, a cubane-like [Pb4(OH)4]4+ group and a [Cu2I6]4− dimer of edge-sharing CuI4 tetrahedra with non-equivalent Cu. Six halocuprate groups surround each [Pb4(OH)4]4+ nucleus, and each halocuprate group is shared between six adjacent [Pb4(OH)4]4+ groups, five long Pb–I bonds are required to complete the co-ordination of each Pb atom. The resulting Pb(OH)3I5 polyhedra are centred on a tetrahedron of O atoms to form a Pb4(OH)4I16 cluster. Siidraite has a unique composition and structure. It is the third naturally occurring halocuprate(I) after marshite and nantokite. A compositionally similar synthetic compound Pb2Cu2(OH)2I2Br has been described that has cubane and CuI4 groups, but a very different structural topology from that of siidraite. Bideauxite, Pb2Ag(OH)FCl3, which has the [Pb4(OH)4]4+ group, shares some topological features with siidraite.
    • Cleaning Minerals: practical and ethical considerations

      Allington-Jones, L (Geological Curators' Group, 2017-11-01)
      Mineral specimens have a dual nature, both as a scientific resource and an aesthetic pleasure. Combine this with a long history of sampling for study, and the developed nature of most specimens on the commercial market, and it is difficult to relate to the ethical principles of conservation when cleaning minerals.
    • Giant Sequoia: an extraordinary case study involving Carbopol® gel

      McKibbin, C; Allington-Jones, L; Verveniotou, E (Archetype Publishing LtdLondon, 2017-10-18)
      In 2016 a project was undertaken to stabilise and aestheticise the transverse section of giant sequoia on display at the Natural History Museum (NHM) in London, UK. This iconic specimen, which now dominates the top floor of the central hall, was 1300 years old when felled and has been part of the exhibitions for 122 years. Measuring over 4.5 metres in diameter, it posed many challenges during remedial conservation. The largest involved removal of the discoloured waxy substance and opacified shellac-based varnish that had been applied in the early 1980s. Solvent tests revealed that the coating was soluble in Industrial Methylated Spirits (IMS) and that the gel worked most effectively at a 1 hour application time. At longer durations the varnish itself gelled and the waxy component was re-deposited. The waxy substance was effectively removed by wiping with alternate white spirit and IMS swabs.
    • A new metriorhynchid crocodylomorph from the Oxford Clay Formation (Middle Jurassic) of England, with implications for the origin and diversification of Geosaurini

      Foffa, Davide; Young, Mark T; Brusatte, Stephen L; Graham, M; Steel, Lorna (Taylor and Francis, 2017-10-02)
      Metriorhynchids are an extinct group of Jurassic–Cretaceous crocodylomorphs secondarily adapted to a marine lifestyle. A new metriorhynchid crocodylomorph from the Oxford Clay Formation (Callovian, Middle Jurassic) of England is described. The specimen is a large, fragmentary skull and associated single ramus of a lower jaw uniquely preserved in a septarian concretion. The description of the specimen reveals a series of autapomorphies (apicobasal flutings on the middle labial surface of the tooth crowns, greatly enlarged basoccipital tuberosities) and a unique combination of characters that warrant the creation of a new genus and species: Ieldraan melkshamensis gen. et sp. nov. This taxon shares numerous characters with the Late Jurassic–Early Cretaceous genus Geosaurus: tooth crowns that have three apicobasal facets on their labial surface, subtly ornamented skull and lower jaws elements, and reception pits along the lateral margin of the dentary (maxillary overbite). Phylogenetic analysis places this new species as the sister taxon to Geosaurus. The new taxon adds valuable information on the time of origin of the macrophagous subclade Geosaurini, which was initially thought to have evolved and radiated during the Late Jurassic. The presence of Ieldraan melkshamensis, the phylogenetic re-evaluation of Suchodus durobrivensis as a Plesiosuchus sister taxon and recently identified Callovian Dakosaurus-like specimens in the Oxford Clay Formation, indicate that all major Geosaurini lineages originated earlier than previously supposed. This has major implications for the evolution of macropredation in the group. Specifically, we can now demonstrate that the four different forms of true ziphodonty observed in derived geosaurins independently evolved from a single non-functional microziphodont common ancestor.
    • Graham MR. (2017) The remedial conservation and support jacketing of the neotype specimen of the dinosaur Massospondylus carinatus

      Graham, M (PeerJ Inc., 2017-08-09)
      In March 2017 the neotype specimen of the Early Jurassic South African prosauropod dinosaur Massospondylus carinatus was appraised and condition reported at the Evolutionary Studies Institute, University of the Witwatersrand (WITS), Johannesburg, in readiness for remedial conservation and re-storage. The work was necessitated by deterioration of the specimen, which was caused by handling over a number of years and an inadequate and failing support mount. Formally numbered BP/1/4934, but more affectionately known to staff as ‘Big Momma’, the specimen was contained within several individual blocks on flimsy support bases and presented various conservation challenges.These included treatment of fractures and cracking across several surfaces of the fossil and the production of clam shell supports to allow for articulated display within the constraints of an existing display cabinet. Part of the brief was to facilitate safer handling and access for researchers. This project was led by the author who also trained the curatorial and preparation staff at WITS in the methods and techniques employed. The visit was funded by the Palaeontological Scientific Trust (PAST), the DST/NRF Centre of Excellence in Palaeosciences and The University of the Witwatersrand (WITS).
    • The remedial conservation and support jacketing of the neotype specimen of the dinosaur Massospondylus carinatus

      Graham, M (PeerJ, 2017-08-09)
      The remedial conservation and support jacketing of the neotype specimen of the dinosaur Massospondylus carinatus
    • Curious bivalves: Systematic utility and unusual properties of anomalodesmatan mitochondrial genomes

      Williams, ST; Foster, PG; Hughes, C; Harper, EM; Taylor, JD; Littlewood, T; Dyal, P; Hopkins, KP; Briscoe, AG (2017-05)
    • Hydroxyferroroméite, a new secondary weathering mineral from Oms, France

      Mills, S; Christy, A; Rumsey, M; Spratt, J; Bittarello, E; Favreau, G; Ciriotti, M; Berbain, C (2017-04-28)
      Hydroxyferroroméite, ideally (Fe2+ 1.5[]0.5)Sb5+ 2O6(OH), is a new secondary mineral from the Correc d'en Llinassos, Oms, Pyrénées-Orientales Department, France. Hydroxyferroroméite occurs as yellow to yellow-brown powdery boxwork replacements up to about 50μm across after tetrahedrite in a siderite–quartz matrix. No distinct crystals have been observed. The empirical formula (based on 7 (O + OH) per formula unit, pfu) is (Fe2+ 1.07Cu2+ 0.50Zn0.03Sr0.03Ca 0.01[]0.36)Σ2 (Sb5+ 1.88Si0.09Al0.02As0.01)Σ2 O6 ((OH)0.86 O0.14). X-ray photoelectron spectroscopy was used to determine the valence states of Sb, Fe and Cu. Hydroxyferroroméite crystallises in the space group Fd3 m with the pyrochlore structure and hence is a new Fe2+ -dominant member of the roméite group of the pyrochlore supergroup. It has the unit-cell parameters: a = 10.25(3) Å, V = 1077(6) Å3 and Z = 8. A model, based on bond-valence theory, for incorporation of the small Fe2+ cation into a displaced variant of the A site of the pyrochlore structure is proposed.
    • The Airless Project

      Allington-Jones, L; Trafford, A (Natural Sciences Collections Association, 2017-04-20)
      A project to combat pyrite oxidation at the NHM (London, UK) is currently in its second year. The project aims to undertake conservation treatments and store highest risk specimens in low oxygen microenvironments. An emergent benefit of the conservation-driven project has been the digitisation of specimens on the collection management system KE Emu, through the use of barcodes and web-based applications.
    • Size effect on the mineralogy and chemistry of Mytilus trossulus shells from the southern Baltic Sea: implications for environmental monitoring

      Piwoni-Piórewicz, A; Kukliński, P; Strekopytov, S; Humphreys-Williams, Emma; Najorka, J; Iglikowska, A (2017-04)