Justin Filiberto^a, Allan H. Treiman^b, Paul A. Giesting^a,c, Cyrena A. Goodrich^d, Juliane Gross^e

^aSouthern Illinois University, Geology Department, Carbondale, IL 62901, USA
^bLunar and Planetary Institute, Houston, TX 77058, USA
^cIllinois State University, Department of Geography–Geology, Normal, IL 61790-4400, USA
^dPlanetary Science Institute, Tucson, AZ 85719, USA
^eAmerican Museum of Natural History, New York, NY 10024, USA

We report scapolite in a melt inclusion in olivine in Nakhla, which is the first occurrence of Cl-scapolite found in a martian meteorite. Using terrestrial metamorphic experiments and modeling we constrain its origin. Cl-rich scapolite in Nakhla is consistent with formation from either a late stage Cl-rich, water-poor magma or magmatic Cl-rich hydrothermal brine at a minimum temperature of 700 °C. The temperature of hydrothermal activity recorded by the Cl-scapolite is significantly higher than the temperatures recorded by alteration minerals in Nakhla, and the fluid was Cl-rich, not CO₂-rich. Our results demonstrate that high-temperature Cl-rich fluids were present within the martian crust, and any potential biologic activity would have to survive in these high temperatures and saline fluids. Halophiles can thrive in NaCl-rich systems but at significantly lower temperatures than those recorded by the scapolite. During cooling of the fluid, the system could have reached a habitable state for halophiles. Importantly, halophiles can survive the conditions of space if they are encased in salt crystals, and therefore chlorine-rich phases present an opportunity to investigate for extant life both on the surface of Mars and in martian meteorites.

Reference
Filiberto J, Treiman AH, Giesting PA, Goodrich CA and Gross J (2014) High-temperature chlorine-rich fluid in the martian crust: A precursor to habitability.  Earth and Planetary Science Letters 401:110.
[doi:10.1016/j.epsl.2014.06.003]
Copyright Elsevier
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Bridges¹ et al. (>10)*
*Find the extensive, full author and affiliation list on the publishers website.

¹Applied Physics Laboratory, Laurel, Maryland, USA

Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity’s cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

Reference
Bridges et al. (in press) The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest.  Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004579]
Published by arrangement with John Wiley & Sons
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Marissa J. F. Rosenberg¹, Olivier Berné^2,3 and Christiaan Boersma⁴

¹Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
²Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
³CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁴NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-0001, USA

The mid-infrared (mid-IR; 5–15 μm) spectrum of a wide variety of astronomical objects exhibits a set of broad emission features at 6.2, 7.7, 8.6, 11.3, and 12.7 μm. About 30 years ago it was proposed that these signatures are due to emission from a family of UV heated nanometer-sized carbonaceous molecules known as polycyclic aromatic hydrocarbons (PAHs), causing them to be referred to as aromatic IR bands (AIBs). Today, the acceptance of the PAH model is far from settled, as the identification of a single PAH in space has not yet been successful, and physically relevant theoretical models involving true PAH cross sections do not reproduce the AIBs in detail. In this paper, we use the NASA Ames PAH IR Spectroscopic Database, which contains over 500 quantum-computed spectra, in conjunction with a simple emission model, to show that the spectrum produced by any random mixture of at least 30 PAHs converges to the same kernel-spectrum. This kernel-spectrum captures the essence of the PAH emission spectrum and is highly correlated with observations of AIBs, strongly supporting PAHs as their source. Furthermore, the fact that a large number of molecules are required implies that spectroscopic signatures of the individual PAHs contributing to the AIBs spanning the visible, near-IR, and far-IR spectral regions are weak, explaining why they have not yet been detected. An improved effort, joining laboratory, theoretical, and observational studies of the PAH emission process, will support the use of PAH features as a probe of physical and chemical conditions in the near and distant Universe.

Reference
Rosenberg MJF, Berné O and Boersma C (2014) Random mixtures of polycyclic aromatic hydrocarbon spectra match interstellar infrared emission.  Astronomy & Astrophysics 566:L4.
[doi:10.1051/0004-6361/201423953]
Reproduced with permission © ESO
Link to Article

P. Koten^a, J. Vaubaillon^b, D. Čapek^a, V. Vojáček^a, P. Spurný^a, R. Štork^a, F. Colas^b

^aAstronomical Institute of the Academy of Sciences, Ondřejov Observatory, Fričova 298, 25165 Ondřejov, Czech Republic
^bInstitut de Mécanique Céleste et de Calcul des Éphémérides – Observatoire de Paris, 77 avenue Denfert-Rochereau, 75014, Paris, France

The very next year following the fall of Neuschwanstein meteorites and discovery of their orbital similarity with the Příbram meteorite, dedicated observational campaigns aiming for the detection of faint meteors on similar orbits were started. The goal of this paper is to process all the data collected within 7 years, to analyse their atmospheric trajectories and heliocentric orbits and to investigate the possibility that they belong to the stream.

The trajectories and orbits of the detected meteors were used to determine whether those meteors are members of the same shower. An orbital evolution model was applied on a certain number of cloned particles to investigate their possible connection with the meteorite stream. Statistical tests were conducted to determine if such small sample of the orbits is similar by chance or if the stream is real. It was found that from the observational as well as the theoretical point of view it is impossible to prove the existence of faint meteor shower connected with the Příbram and Neuschwanstein meteorite stream.

Reference
Koten P, Vaubaillon J, Čapek D, Vojáček V, Spurný P, Štork R and Colas F (in press) Search for faint meteors on the orbits of Příbram and Neuschwanstein meteorites.  Icarus
[doi:10.1016/j.icarus.2014.06.014]
Copyright Elsevier
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