Elena MARTELLATO¹, Valerio VIVALDI^2,3, Matteo MASSIRONI², Gabriele CREMONESE³,Francesco MARZARI⁴, Andrea NINFO⁵, and Junichi HARUYAMA⁶
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12892]
¹Museum f€ur Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
²Dipartimento di Geoscienze, Universita degli Studi di Padova, via Gradenigo 6, I-35131 Padova, Italy
³INAF-Osservatorio Astronomico di Padova, vic. Osservatorio 5, 35122 Padova, Italy
⁴Dipartimento di Fisica e Astronomia “Galileo Galilei,” Universita degli Studi di Padova, via Marzolo 8, 35131 Padova, Italy
⁵Dipartimento di Fisica e Scienze della Terra, Univerista di Ferrara, via Saragat 1, 44122 Ferrara, Italy
⁶Department of Solar System Sciences, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency,Sagamihara, Kanagawa 252-5210, Japan
Published by arrangement with John Wiley & Sons

Linné is a simple crater, with a diameter of 2.23 km and a depth of 0.52 km, located in northwestern Mare Serenitatis. Recent high-resolution data acquired by the Lunar Reconnaissance Orbiter Camera revealed that the shape of this impact structure is best described by an inverted truncated-cone. We perform morphometric measurements, including slope and profile curvature, on the Digital Terrain Model of Linné, finding the possible presence of three subtle topographic steps, at the elevation of +20, −100, and −200 m relative to the target surface. The kink at −100 m might be related to the interface between two different rheological layers. Using the iSALE shock physics code, we numerically model the formation of Linné crater to derive hints on the possible impact conditions and target physical properties. In the initial setup, we adopt a basaltic projectile impacting the Moon with a speed of 18 km s⁻¹. For the local surface, we consider either one or two layers, in order to test the influence of material properties or composite rheologies on the final crater morphology. The one-layer model shows that the largest variations in the crater shape take place when either the cohesion or the friction coefficient is varied. In particular, a cohesion of 10 kPa marks the threshold between conical- and parabolic-shaped craters. The two-layer model shows that the interface between the two layers would be exposed at the observed depth of 100 m when an intermediate value (~200 m) for the upper fractured layer is set. We have also found that the truncated-cone morphology of Linné might originate from an incomplete collapse of the crater wall, as the breccia lens remains clustered along the crater walls, while the high-albedo deposit on the crater floor can be interpreted as a very shallow lens of fallout breccia. The modeling analysis allows us to derive important clues on the impactor size (under the assumption of a vertical impact and collision velocity equal to the mean value), and on the approximate, large-scale preimpact target properties. Observations suggest that these large-scale material properties likely include some important smaller scale variations, disclosed as subtle morphological steps in the crater walls. Furthermore, the modeling results allow advancing some hypotheses on the geological evolution of the Mare Serenitatis region where Linné crater is located (unit S14). We suggest that unit S14 has a thickness of at least a few hundreds of meters up to about 400 m.

Robert M. Howie¹, Jonathan Paxman¹, Philip A. Bland², Martin C. Towner²,Eleanor K. Sansom², and Hadrien A. R. Devillepoix²
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12878]
¹Department of Mechanical Engineering, Curtin University, Perth, Western Australia 6845, Australia
²Department of Applied Geology, Curtin University, Perth, Western Australia 6845, Australia
Published by arrangement with John Wiley & Sons

Long-exposure fireball photographs have been used to systematically record meteoroid trajectories, calculate heliocentric orbits, and determine meteorite fall positions since the mid-20th century. Periodic shuttering is used to determine meteoroid velocity, but up until this point, a separate method of precisely determining the arrival time of a meteoroid was required. We show it is possible to encode precise arrival times directly into the meteor image by driving the periodic shutter according to a particular pattern—a de Bruijn sequence—and eliminate the need for a separate subsystem to record absolute fireball timing. The Desert Fireball Network has implemented this approach using a microcontroller driven electro-optic shutter synchronized with GNSS UTC time to create small, simple, and cost-effective high-precision fireball observatories with submillisecond timing accuracy.

¹Rachel L. Klima, ²Noah E. Petro
Philosophical Transactions of the Royal Society A 375 Link to Article [https://doi.org/10.1098/rsta.2015.0391]
¹Space Exploration Sector, Planetary Exploration Group, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
²NASA Goddard Space Flight Center, Greenbelt, MD, USA

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¹L.J.Hallis
Philosophical Transactions of the Royal Society A 375 Link to Article [DOI: 10.1098/rsta.2015.0390]
¹School of Geographical and Earth Sciences, Gregory Building, University of Glasgow, Glasgow G12 8QQ, UK

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^1,2S. Sutton, ³C.M.O’D. Alexander, ¹A. Bryant, ¹A. Lanzirotti, ¹M. Newville, ⁴E.A. Cloutis
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2017.05.021]
¹Center for Advanced Radiation Sources, 5640 S. Ellis Avenue, University of Chicago, Chicago, IL 60637, USA
²Department of Geophysical Sciences, 5640 S. Ellis Avenue, University of Chicago, Chicago, IL 60637, USA
³DTM, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, DC 20015, USA
⁴Department of Geography, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada, R3B 2E9.
Copyright Elsevier

There is abundant petrologic evidence for the oxidation of Fe during the aqueous alteration of chondrites, and water must have been the oxidant for this process. The H2 lost from the chondrite parent bodies as a result of Fe oxidation would have been isotopically very light, enriching any residual water in D. The extents of the D enrichments will have depended on the fractions of water consumed and the temperatures during Fe oxidation. Here we have estimated the likely ranges of water consumed by Fe oxidation in the CI, CM, CR and LL parent bodies, as well as the likely range of changes in water H isotopic compositions this would have produced. We first used Fe XANES to determine the Fe valences of bulk meteorite powders in Orgueil (CI1), a number of CMs and CRs that experienced varying degrees of alteration, and Semarkona (LL3.00). The total ranges of bulk Fe valences we obtained were: Orgueil 2.77, CMs 2.40-2.63, CRs 1.46-2.54, and Semarkona 2.10. Combining previous estimates of the present water/OH contents of our samples with the present bulk Fe valences and an estimated range of initial bulk Fe valences, we estimate the likely ranges of fractional water losses to have been: Orgueil 15-26%, Semarkona 73-83%, CMs 23-48%, and CRs 39-62%. The associated maximum and minimum changes in the H isotopic compositions of the remaining water were estimated assuming the equilibrium H2-H2O isotopic fractionation factor, Rayleigh fractionation of the H2, and oxidation temperatures of 0-200°C. Using previous estimates of the water H isotopic compositions in the chondrites, the ranges of estimated δD values for the initial chondritic waters are: Orgueil -672 ‰ to -422 ‰, CMs -676 ‰ to -493 ‰, CRs -527 ‰ to -56 ‰, and Semarkona -527 ‰ to 154 ‰. The CI, CM, CR and ordinary chondrites all accreted water with similar H isotopic compositions that were distinct from the compositions of comets or Saturn’s moon Enceladus. Thus, the carbonaceous chondrites are unlikely to have come from comets or from bodies that were scattered into the Asteroid Belt from comet forming regions by orbital migration of the giant planets. If the carbonaceous chondrites did form in the outer Solar System, as some models predict, it was probably not beyond 7 AU. However, based on water isotopic compositions at present it is equally plausible that the carbonaceous chondrites formed in the inner Solar System.

¹Maksimova, A.A., ¹Oshtrakh, M.I., ²Felner, I., ¹Chukin, A.V., ³Karabanalov, M.S., ¹Semionkin, V.A.
Journal of Molecular Structure 1140, 122-126 Link to Article [DOI: 10.1016/j.molstruc.2016.11.042]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation
²Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
³Institute of Material Science and Metallurgy, Ural Federal University, Ekaterinburg, Russian Federation

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¹Bossin, L., ^2,3Kazakis, N.A., ³Kitis, G., ²Tsirliganis, N.C.
Applied Radiation and Isotopes 127, 26-34 Link to Article [DOI: 10.1016/j.apradiso.2017.05.002]
¹Department of Archaeology, Durham University, United Kingdom
²Laboratory of Archaeometry and Physicochemical Measurements, R.C. ‘Athena’, Kimmeria University Campus, P.O. Box 159, Xanthi, Greece
³Nuclear Physics Laboratory, Physics Department, Aristotle University of Thessaloniki, Thessaloniki, Greece

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¹Elewa, N.N., ¹Cadogan, J.M.
Hyperfine Interactions 238, 4 Link to Article [DOI: 10.1007/s10751-016-1350-1]
¹School of Physical, Environmental and Mathematical Sciences, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT, Australia

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¹Koga, T., ^1,2Naraoka, H.
Scientific Reports 7, 636 Link to Article [DOI: 10.1038/s41598-017-00693-9]
¹Department of Earth and Planetray Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan
²Research Center for Planetary Trace Organic Compounds, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan

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¹G.G. Managadze, ¹A.A. Safronova, ¹K.A. Luchnikov, ^1,2E.A. Vorobyova, ^3,4N.S. Duxbury, ⁵P. Wurz, ¹N.G. Managadze, ¹Chumikov, ⁶R.Kh. Khamizov
Astrobiology 17, 448-458 Link to Article [https://doi.org/10.1089/ast.2016.1511]
¹Space Research Institute, Russian Academy of Sciences, Moscow, Russian Federation.
²Soil Science Faculty, Lomonosov Moscow State University, Moscow, Russian Federation.
³Department of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia, USA.
⁴Geology Faculty, Lomonosov Moscow State University, Moscow, Russian Federation.
⁵Physics Institute, University of Bern, Bern, Switzerland.
⁶Institute of Geological Chemistry, Russian Academy of Sciences, Moscow, Russian Federation.

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