Ming-Chang Liu

Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan

Injection of short-lived radionuclides from a nearby core-collapse Type II supernova into the already-formed solar protoplanetary disk was proposed to account for the former presence of ²⁶Al, ⁴¹Ca, and ⁶⁰Fe in the early solar system inferred from isotopic analysis of meteoritic samples. One potential corollary of this “late-injection” scenario is that the disk’s initial (pre-injection) oxygen isotopic composition could be significantly altered, as supernova material that carried the short-lived radionuclides would also deliver oxygen components synthesized in that given star. Therefore, the change in the oxygen isotopic composition of the disk caused by injection could in principle be used to constrain the supernova injection models. Previous studies showed that although supernova oxygen could result in a wide range of shifts in ¹⁷O/¹⁶O and ¹⁸O/¹⁶O of the disk, a couple of cases existed where the calculated oxygen changes in the disk would be compatible with the meteoritic and solar wind data. Recently, the initial abundances of ⁴¹Ca and ⁶⁰Fe in the solar system were revised to lower values, and the feasibility of supernova injection as a source for the three radionuclides was called into question. In this study, supernova parameters needed for matching ²⁶Al, ⁴¹Ca, and ⁶⁰Fe to their early solar system abundances were reinvestigated and then were used to infer the pre-injection O-isotope composition of the disk. The result suggested that a supernova undergoing mixing fallback might be a viable source for the three radionuclides.

Reference
Liu MC (2014) On the Injection of Short-lived Radionuclides from a Supernova into the Solar Nebula: Constraints from the Oxygen Isotopes. The Astrophysical Journal – Letters 781:L28.
[doi:10.1088/2041-8205/781/2/L28]

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Sautter V¹ et al. (>10)*
*Find the extensive, full author and affiliation list on the publishers website.

¹LMCM, UMR-CNRS 7202, MNHN, Paris, France

Textural and compositional analyses using Chemistry Camera (ChemCam) remote microimager and laser-induced breakdown spectroscopy (LIBS) have been performed on five float rocks and coarse gravels along the first 100 m of the Curiosity traverse at Bradbury Rise. ChemCam, the first LIBS instrument sent to another planet, offers the opportunity to assess mineralogic diversity at grain-size scales (~100 µm) and, from this, lithologic diversity. Depth profiling indicates that targets are relatively free of surface coatings. One type of igneous rock is volcanic and includes both aphanitic (Coronation) and porphyritic (Mara) samples. The porphyritic sample shows dark grains that are likely pyroxene megacrysts in a fine-grained mesostasis containing andesine needles. Both types have magnesium-poor basaltic compositions and in this respect are similar to the evolved Jake Matijevic rock analyzed further along the Curiosity traverse both with Alpha-Particle X-ray Spectrometer and ChemCam instruments. The second rock type encountered is a coarse-grained intrusive rock (Thor Lake) showing equigranular texture with millimeter size crystals of feldspars and Fe-Ti oxides. Such a rock is not unique at Gale as the surrounding coarse gravels (such as Beaulieu) and the conglomerate Link are dominated by feldspathic (andesine-bytownite) clasts. Finally, alkali feldspar compositions associated with a silica polymorph have been analyzed in fractured filling material of Preble rock and in Stark, a putative pumice or an impact melt. These observations document magmatic diversity at Gale and describe the first fragments of feldspar-rich lithologies (possibly an anorthosite) that may be ancient crust transported from the crater rim and now forming float rocks, coarse gravel, or conglomerate clasts.

Reference
Sautter V et al. (in press) Igneous mineralogy at Bradbury Rise: The first ChemCam campaign at Gale crater. Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004472]
Published by arrangement with John Wiley & Sons

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Lorenz Roth^1,2,*,†, Joachim Saur^2,†, Kurt D. Retherford¹, Darrell F. Strobel^3,4, Paul D. Feldman⁴, Melissa A. McGrath⁵, Francis Nimmo⁶

¹Southwest Research Institute, San Antonio, TX, USA.
²Institute of Geophysics and Meteorology, University of Cologne, Germany.
³Department of Earth and Planetary Science, The Johns Hopkins University, Baltimore, MD, USA.
⁴Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA.
⁵NASA Marshall Space Flight Center, Huntsville, AL, USA.
^† These authors contributed equally to this work.

In November and December 2012, the Hubble Space Telescope (HST) imaged Europa’s ultraviolet emissions in the search for vapor plume activity. We report statistically significant coincident surpluses of hydrogen Lyman-α and oxygen OI 130.4-nanometer emissions above the southern hemisphere in December 2012. These emissions were persistently found in the same area over the 7 hours of the observation, suggesting atmospheric inhomogeneity; they are consistent with two 200-km-high plumes of water vapor with line-of-sight column densities of about 1020 per square meter. Nondetection in November 2012 and in previous HST images from 1999 suggests varying plume activity that might depend on changing surface stresses based on Europa’s orbital phases. The plume was present when Europa was near apocenter and was not detected close to its pericenter, in agreement with tidal modeling predictions.

Reference
Roth L, Joachim Saur J, Retherford KD, Strobel DF, Feldman PD, McGrath MA and Nimmo F (2014) Transient Water Vapor at Europa’s South Pole. Science 343:171-174.
[doi:10.1126/science.1247051]
Reprinted with permission from AAAS

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John R. Spencer

Southwest Research Institute, 1050 Walnut Street, Boulder, CO 80302, USA.

Second-closest to Jupiter (after Io) of the four large Galilean satellites, icy Europa is one of the strangest objects in the solar system (1). On page 171 of this issue, Roth et al. (2) present strong evidence for ongoing eruptions of plumes of water vapor from Europa’s surface. This is a potentially major discovery, making Europa only the fourth object in the solar system known to exhibit ongoing internally powered geological activity, after Earth, Europa’s volcanic neighbor moon Io, and Saturn’s icy moon Enceladus.

Reference
Spencer JR (2014) Glimpsing Eruptions on Europa. Science 343:148-149.
[doi:10.1126/science.1248879]
Reprinted with permission from AAAS

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E. Stokan and M.D. Campbell-Brown

Department of Physics and Astronomy, University of Western Ontario, London, Canada, N6A 3K7

Nine fragmenting, faint meteors (peak magnitude ∼+1, mass <10^-4 kg) were observed with the Canadian Automated Meteor Observatory (CAMO). Fragments for eight of the nine meteors exhibited significant transverse motion, perpendicular to the meteor velocity. Transverse speeds of the order 100 m s^-1 were observed, while models of aerodynamic loading predict speeds of the order 0.5 m s^-1. Acceleration of the fragments in the transverse direction was negligible. Alternate methods of fragmentation, namely rotation and electrostatic charge accumulation, were examined through basic models to explain the observed transverse speeds. Meteoroid strengths of the order 10⁶ Pa were derived, matching observed strengths of larger, brighter meteors.

Reference
Stokan E and Campbell-Brown MD (in press) Transverse motion of fragmenting faint meteors observed with the Canadian Automated Meteor Observatory. Icarus
[doi:10.1016/j.icarus.2014.01.002]
Copyright Elsevier

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Paul D. Spudis^1,*, Dayl J. P. Martin^1,2 and Georgiana Kramer¹

¹Lunar and Planetary Institute, Houston, Texas, USA
²School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK

The Orientale Basin is one of the largest (930 km diameter) and youngest (~3.8 Ga) impact craters on the Moon. As the basin is only partly flooded by mare lava, its floor materials expose a major portion of the basin impact melt sheet, which some previous work has suggested might have undergone igneous differentiation. To test this idea, we remapped the geology of the Orientale Basin using images and topography from the Lunar Reconnaissance Orbiter, mineralogical information from the Chandrayaan-1 Moon Mineralogy Mapper, and elemental concentration maps from Clementine multispectral imaging and Lunar Prospector gamma ray data. The Maunder Formation (impact melt sheet of the basin) is uniform in chemical composition (equivalent to “anorthositic norite”) in at least the upper 2 km of the deposit. The deepest sampling of the basin melt sheet (maximum depths of ~3–5 km by the crater Maunder, 55 km in diameter) shows a variety of lithologies, but these rock types (anorthosite, anorthositic norite melt rocks, mare basalt, and gabbro) are not those predicted by the differentiation model. We conclude that no differentiation of the Orientale Basin melt sheet has occurred and that such a process is not evident from new remote sensing data for the Moon or in the Apollo lunar samples.

Reference
Spudis PD, Martin DJP and Kramer G (in press) Geology and composition of the Orientale Basin impact melt sheet. Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004521]
Published by arrangement with John Wiley & Sons

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Julien Stodolna, Zack Gainsforth, Anna L. Butterworth and Andrew J. Westphal

Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA

We report the presence of preserved primitive fine-grained material containing an enstatite whisker with the crystallographic characteristics of a primary condensate in a sample of the Jupiter-family comet Wild 2, returned to earth by NASAʼs Stardust mission. The preserved primitive material is composed of silica-rich amorphous material embedded with iron sulfides and silicates. It is in close association with a type II chondrule-like object in the track C2052,2,74 (Ogliore et al., 2012). The close association of a chondrule and a primary condensate shows they must have formed in different environments and probably met in the comet-forming region. The first observation of an enstatite whisker with properties indicating primary condensation in a comet is a new link between comets and Chondritic Porous IDPs (CP-IDPs).

Reference
Stodolna J, Gainsforth Z, Butterworth AL and Westphal AJ (2014) Characterization of preserved primitive fine-grained material from the Jupiter family comet 81P/Wild 2 – A new link between comets and CP-IDPs. Earth and Planetary Science Letters 388:367–373.
[doi:10.1016/j.epsl.2013.12.018]
Copyright Elsevier

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José M. Madiedo^a,b, José L. Ortiz^c, Josep M. Trigo-Rodríguez^d, Joan Dergham^d, Alberto J. Castro-Tirado^c, Jesús Cabrera-Caño^b, Pep Pujols^e

^aFacultad de Física. Departamento de Física Atómica, Molecular y Nuclear. Universidad de Sevilla, 4012 Sevilla, Spain
^bFacultad de Ciencias Experimentales. Universidad de Huelva, 21071 Huelva, Spain
^cInstituto de Astrofísica de Andalucía, CSIC, Apt. 3004, Camino Bajo de Huetor 50, 18080 Granada, Spain
^dInstitute of Space Sciences (CSIC-IEEC), Campus UAB, Facultat de Ciències, Torre C5-parell-2ª, 08193 Bellaterra, Barcelona, Spain
^eGrup d’Estudis Astronòmics (GEA) and Agrupació Astronòmica d’Osona, Barcelona, Spain

We present the analysis of five bright fireballs observed over Spain and France between 2010 and 2012. Their absolute magnitude ranged between -9.0 and -11.5. Radiant and orbital data indicate that these events were associated with the Taurid meteoroid stream. Their trajectory in the atmosphere is calculated and the heliocentric orbit of the meteoroids is obtained. The emission spectra produced by three of these fireballs are also discussed, and the chemical nature of the parent impactors is inferred, together with different physical parameters of these particles such as the meteoroid mass and tensile strength. On the basis of these results, the ability of Taurid meteoroids to produce meteorites is discussed.

Reference
Madiedo JM, Ortiz JL, Trigo-Rodríguez JM, Dergham J, Castro-Tirado AJ, Cabrera-Caño J and Pujols P (in press) Analysis of bright Taurid fireballs and their ability to produce meteorites. Icarus
[doi:10.1016/j.icarus.2013.12.025]
Copyright Elsevier

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Arya Udry*, J. Brian Balta, Harry Y. McSween Jr.

Planetary Geosciences Institute, Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA

Martian primary compositions, i.e., magmas that did not experience fractionation and/or contamination after extraction from the mantle, occur as a subset of Martian meteorites and a few lavas analyzed on the planet’s surface by rovers. Eruptions of primary magmas are rare on Earth and presumably on Mars. Previous studies of fractional crystallization of Martian primary magmas have been conducted under isobaric conditions, simulating idealized crystallization in magma chambers. Polybaric fractionation, which occurs during magma ascent, has not been investigated in detail for Martian magmas. Using the MELTS algorithm and the pMELTS revision, we present comprehensive isobaric and polybaric thermodynamic calculations of the fractional crystallization of four primary or parental Martian magmas (Humphrey, Fastball, Y-980459 shergottite, and nakhlite parental melts) using various pressure-temperature paths, oxygen fugacities, and water contents to constrain how these magmas might evolve. We then examine whether known Martian alkaline rock compositions could have formed through fractional crystallization of these magmas under the simulated conditions. We find that isobaric and polybaric crystallization paths produce similar residual melt compositions, but given sufficient details, we may be able to distinguish between them. We calculate that Backstay (Gusev Crater) likely formed by fractionation of a primary magma under polybaric conditions, while Jake_M (Gale Crater) may have formed through melting of a metasomatized mantle, crustal assimilation, or fractional crystallization of an unknown primary magma. The best fits for the Backstay composition indicate that consideration of polybaric crystallization paths can help improve the quality of fit when simulating liquid lines of descent.

Reference
Udry A, Balta JB and McSween Jr. HY (in press) Exploring fractionation models for Martian magmas. Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004445]
Published by arrangement with John Wiley & Sons

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Chi Ma*, John R. Beckett and George R. Rossman

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, U.S.A.

Monipite (IMA 2007-033), MoNiP, is a new phosphide mineral that occurs as one 1 × 2 μm crystal in a Type B1 Ca-Al-rich inclusion (CAI) ACM-2 from the Allende CV3 carbonaceous chondrite. It has an empirical formula of (Mo_0.84Fe_0.06Co_0.04Rh_0.03)(Ni_0.89Ru_0.09)P, and a P6̄ 2m Fe₂P type structure with a = 5.861, c = 3.704 Å, V = 110.19 ų, and Z = 3. The calculated density using our measured composition is 8.27 g/cm³, making monipite the densest known mineral phosphide. Monipite probably either crystallized from an immiscible P-rich melt that had exsolved from an Fe-Ni-enriched alloy melt that formed during melting of the host CAI or it exsolved from a solidified alloy. Most of the original phosphide in the type occurrence was later altered to apatite and Mo-oxides, leaving only a small residual grain. Monipite occurs within an opaque assemblage included in melilite that contains kamiokite (Fe₂Mo₃O₈), tugarinovite (MoO₂), and a Nb-rich oxide [(Nb,V,Fe)O₂], none of which has previously been reported in meteorites, together with apatite, awaruite (Ni₂Fe), and vanadian magnetite.

Reference
Ma C, Beckett JR and Rossman GR (2014) Monipite, MoNiP, a new phosphide mineral in a Ca-Al-rich inclusion from the Allende meteorite. American Mineralogist 99:198-205.
[doi:10.2138/am.2014.4512]
Copyright: The Mineralogical Society of America

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