Y.-M. Lim¹, K.-W. Min¹, P. D. Feldman², W. Han³, and J. Edelstein⁴

¹Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea
²Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
³Korea Astronomy and Space Science Institute (KASI), 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Korea
⁴Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA

We present the results of far-ultraviolet observations of comet C/2001 Q4 (NEAT) that were made with the Far-Ultraviolet Imaging Spectrograph on board the Korean satellite STSAT-1. The observations were conducted in two campaigns during its perihelion approach between 2004 May 8 and 15. Based on the scanning mode observations in the wavelength band of 1400-1700 Å, we have constructed an image of the comet with an angular size of 5°×5°, which corresponds to the central coma region. Several important fluorescence emission lines were detected including S I multiplets at 1429 and 1479 Å, C I multiplets at 1561 and 1657 Å, and the CO A¹Π-X¹Σ⁺ Fourth Positive system; we have estimated the production rates of the corresponding species from the fluxes of these emission lines. The estimated production rate of CO was Q_CO = (2.65 ± 0.63) × 10²⁸ s^-1, which is 6.2%-7.4% of the water production rate and is consistent with earlier predictions. The average carbon production rate was estimated to be QC  = ~1.59 × 10²⁸ s^-1, which is ~60% of the CO production rate. However, the observed carbon profile was steeper than that predicted using the two-component Haser model in the inner coma region, while it was consistent with the model in the outer region. The average sulfur production rate was QS  = (4.03±1.03) × 10²⁷ s^-1, which corresponds to ~1% of the water production rate.

Reference
Lim Y-M, Min K-W, Feldman PD, Han W and Edelstein J (2014) Far-ultraviolet Observations of Comet C/2001 Q4 (NEAT) with FIMS/SPEAR. The Astrophysical Journal 781:80.
[doi:10.1088/0004-637X/781/2/80]

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Marc D. Norman^a,b and Alexander A. Nemchin^c

^aLunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, USA
^bResearch School of Earth Sciences, Australian National University, Mills Road, Canberra, ACT 0200, Australia
^cDepartment of Applied Geology, Curtin University of Technology, Perth, WA 6845, Australia

A sharp rise in the flux of asteroid-size bodies traversing the inner Solar System at 3.9 Ga has become a central tenet of recent models describing planetary dynamics and the potential habitability of early terrestrial environments. The prevalence of ~3.9 Ga crystallization ages for lunar impact-melt breccias and U–Pb isotopic compositions of lunar crustal rocks provide the primary evidence for a short-lived, cataclysmic episode of late heavy bombardment at that time. Here we report U–Pb isotopic compositions of zirconolite and apatite in coarse-grained lunar melt rock 67955, measured by ion microprobe, that date a basin-scale impact melting event on the Moon at 4.22±0.01 Ga followed by entrainment within lower grade ejecta from a younger basin approximately 300 million yr later. Significant impacts prior to 3.9 Ga are also recorded by lunar zircons although the magnitudes of those events are difficult to establish. Other isotopic evidence such as ⁴⁰Ar–³⁹Ar ages of granulitic lunar breccias, regolith fragments, and clasts extracted from fragmental breccias, and Re–Os isotopic compositions of lunar metal is also suggestive of impact-related thermal events in the lunar crust during the period 4.1–4.3 Ga. We conclude that numerous large impactors hit the Moon prior to the canonical 3.9 Ga cataclysm, that some of those pre-cataclysm impacts were similar in size to the younger lunar basins, and that the oldest preserved lunar basins are likely to be significantly older than 3.9 Ga. This provides sample-based support for dynamical models capable of producing older basins on the Moon and discrete populations of impactors. An extended period of basin formation implies a less intense cataclysm at 3.9 Ga, and therefore a better opportunity for preservation of early habitable niches and Hadean crust on the Earth. A diminished cataclysm at 3.9 Ga suggests that the similarity in the age of the oldest terrestrial continental crust with the canonical lunar cataclysm is likely to be coincidental with no genetic significance.

Reference
Norman MD and Alexander A. Nemchin AA (in press) A 4.2 billion year old impact basin on the Moon: U–Pb dating of zirconolite and apatite in lunar melt rock 67955. Earth and Planetary Science Letters
[doi:10.1016/j.epsl.2013.11.040]
Copyright Elsevier

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Romain Tartèse^a and Mahesh Anand^b

^aPlanetary and Space Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
^bDepartment of Earth Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom

Refers To
Romain Tartèse, Mahesh Anand
Late delivery of chondritic hydrogen into the lunar mantle: Insights from mare basalts
Earth and Planetary Science Letters, Volume 361, 1 January 2013, Pages 480-486

The authors regret for an error which was introduced in an intermediate step involved in calculating the amount of chondritic material added to the lunar interior to account for the estimated H content of the mare basalt source regions (Section 6, lines 12–25). The revised text is as follows:
Assuming a 400 km deep solidified mantle with 25 ppm H and a density of 3300 kg m⁻³ implies that ~1×10¹⁸ kg of H has been added by chondrite-type impactors and efficiently mixed in the upper lunar mantle. Taking the measured H content of ~5000–15 000 ppm in CI chondrites (Alexander et al., 2012 and Kerridge, 1985), this represents a mass of about 6.2×10¹⁹ to 1.8×10²⁰ kg of CI-type material accreted to the lunar upper mantle. This corresponds to 0.2–0.5 wt.% of the 400 km deep upper mantle considered here. By comparison, HSE abundances in lunar basalts require an amount of ~1.6×10¹⁹ kgof chondritic material to have been accreted and mixed into the lunar upper mantle (Bottke et al., 2010 and Day et al., 2007), around 8±4 times less than that required for a lunar mantle with 25 ppm H.

Reference
Tartèse R and Mahesh Anand M (in press) Corrigendum to “Late delivery of chondritic hydrogen into the lunar mantle: Insights from mare basalts” [Earth Planet. Sci. Lett. 361 (2013) 480–486]. Earth and Planetary Science Letters
[doi:10.1016/j.epsl.2014.01.002]
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Pavlo P. Korsun^a, Philippe Rousselot^b, Irina V. Kulyk^a, Viktor L. Afanasiev^c, Oleksandra V. Ivanova^a

^aMain Astronomical Observatory of NAS of Ukraine, Akademika Zabolotnoho 27, 03680 Kyiv, Ukraine
^bUniversity of Franche-Comté, Observatoire des Sciences de l’Univers THETA, Institut UTINAM – UMR CNRS 6213, BP 1615, 25010 Besançon Cedex, France
^cSpecial Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz, 369167, Russia

Spectrophotometric monitoring of distant comet C/2002 VQ94 (LINEAR) was performed with the 6-m telescope of SAO RAS (Special Astrophysical Observatory of Russian Academy of Sciences) and with the 2.5-m Nordic Optical Telescope (Observatory del Roque de los Muchachos, Canarias, Spain) between 2008 and 2013. During this period the comet was on the outbound segment of its orbit, between heliocentric distances of 8.36 au and 16.84 au. Analysis of the spectra revealed the presence of the CO⁺ and N₂⁺emissions in the cometary coma at a distance of 8.36 au from the Sun. This distance is larger than ionic emissions have been detected in any previous objects. Only continuum, with no traces of emissions, was detected in the spectrum obtained in 2009 when the comet was at a distance of 9.86 au. From the spectra obtained in 2008, average column densities of 2.04×10⁹ mol cm^-2 for N₂⁺ and 3.26×10¹⁰ mol cm^-2 for CO⁺were measured in the cometary coma. The derived values correspond to N₂⁺/CO⁺=0.06 within the projected slit. Images obtained through a red continuum filter in 2008 showed a bright, dust coma, indicating a high level of physical activity. A considerably lower level of activity was observed in 2009 and 2011 at distances of 9.86 au and 13.40 au respectively. No noticeable activity was detected in 2013 at a heliocentric distance of 16.84 au.The Afρ parameter, which is used as an indicator of cometary activity, was measured as 2000 cm in 2008, and 800 cm in 2009 and 2011. The Afρ values correspond to dust production rates between 10-20 kg s^-1, 4-6 kg s^-1 and 3-5 kg s^-1 at 8.36, 9.86, and 13.40 au respectively. There is an obvious correlation between the decrease of the dust production rate of the nucleus and the disappearance of the emissions in the spectrum of C/2002 VQ94 (LINEAR) at heliocentric distances greater than 9 au. The colors and size of the nucleus of C/2002 VQ94 (LINEAR) were estimated from the images obtained during the late stage at a heliocentric distance of 16.84 au, when the activity had probable ceased. The B-V and V-R colors were estimated to be 1.07±0.05 and 0.54±0.03 respectively. The effective nucleus radius of 482 km is in agreement with the previously published results, obtained from the observations of the comet during its early inactive stage ( and ).

Reference
Korsun PP, Philippe Rousselot P, Kulyk IV, Afanasiev VL and Ivanova OV (in press) Distant activity of comet C/2002 VQ94 (LINEAR): optical spectrophotometric monitoring between 8.4 and 16.8 au from the Sun. Icarus
[doi:10.1016/j.icarus.2014.01.006]
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G.J. Archer^a, R.D. Ash^a, E.S. Bullock^b, R.J. Walker^a

^aDepartment of Geology, University of Maryland, College Park, MD 20742
^bDepartment of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560

The abundances of highly siderophile elements (HSE) Re, Os, Ir, Ru, Pt, and Pd, as well as ¹⁸⁷Re-¹⁸⁷Os isotopic systematics were determined for calcium-aluminum-rich inclusions (CAIs), chondrules, and matrix, separated from the CV3 carbonaceous chondrite Allende. Consistent with prior studies, CAIs are characterized by significant depletions in Pd relative to the other HSE, while the other HSE are in generally bulk chondritic relative abundances. The depletions in Pd can be linked with initial formation of CAIs via condensation, or subsequent processing by evaporative processes. Chondrules generally have relative HSE patterns similar to CAIs, although they have lower absolute abundances. Palladium depletions in chondrules may reflect solid metal-liquid metal fractionation at the time of formation, or alternatively, be the result of processes that acted on precursor materials. Matrix samples have nearly chondritic absolute abundances of all HSE measured. Consequently, matrix is the only major chondritic component examined here that shows no relative depletion in Pd. Mass balance suggests the existence of an unidentified Pd-rich carrier, although it is possible that the dataset presented here is too limited to represent typical HSE abundances of some chondritic components (e.g., chondrules).
The ¹⁸⁷Re-¹⁸⁷Os isotopic systematics of only six out of twenty-four Allende chondritic components analyzed plot within uncertainties of a 4568 Ma primordial reference isochron. The deviations from the expected isochron most likely reflect late-stage, open-system behavior within the last 2 billion years, and, in some cases, could even have resulted from terrestrial alteration. The open-system behavior is most readily observed in small, millimeter-size sub-samples of Allende, consistent with Re and/or Os mobility on that scale.

Reference
Archer GJ, Ash RD, Bullock ES and Walker RJ (in press) Highly Siderophile Elements and 187Re-187Os Isotopic Systematics of the Allende Meteorite: Evidence for Primary Nebular Processes and Late-stage Alteration. Geochimica et Cosmochimica Acta
[doi:10.1016/j.gca.2013.12.032]
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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]
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