¹Alessondra Springmann, ¹Dante S.Lauretta, ²Bjoern Klaue, ³Yulia S.Goreva, ⁴Joel D.Blum, ⁵Alexandre Andronikov, ^6,7Jordan K.Steckloff
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.12.022]
¹Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, United States
²TSI GMBH, Neuköllner Strasse 4, Aachen, 52068, Germany
³NASA Jet Propulsion Laboratory, Pasadena, CA, 91109, United States
⁴Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, United States
⁵Czech Geological Survey, Geologicka 6, Prague, 152 00, Czech Republic
⁶Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX, 78712, United States
⁷Planetary Science Institute, Tucson, AZ, 85719, United States
Copyright Elsevier

Carbonaceous chondrite meteorites are some of the oldest Solar System planetary materials available for study. The CI group has bulk abundances of elements similar to those of the solar photosphere. Of particular interest in carbonaceous chondrite compositions are labile elements, which vaporize and mobilize efficiently during post-accretionary parent-body heating events. Thus, they can record low-temperature alteration events throughout asteroid evolution. However, the precise nature of labile-element mobilization in planetary materials is unknown. Here we characterize the thermally induced movements of the labile elements S, As, Se, Te, Cd, Sb, and Hg in carbonaceous chondrites by conducting experimental simulations of volatile-element mobilization during thermal metamorphism. This process results in appreciable loss of some elements at temperatures as low as 500 K. This work builds on previous laboratory heating experiments on primitive meteorites and shows the sensitivity of chondrite compositions to excursions in temperature. Elements such as S and Hg have the most active response to temperature across different meteorite groups. Labile element mobilization in primitive meteorites is essential for quantifying elemental fractionation that occurred on asteroids early in Solar System history. This work is relevant to maintaining a pristine sample from asteroid (101955) Bennu from the OSIRIS-REx mission and constraining the past orbital history of Bennu. Additionally, we discuss thermal effects on surface processes of near-Earth asteroids, including the thermal history of “rock comets” such as (3200) Phaethon. This work is also critical for constraining the concentrations of contaminants in vaporized water extracted from asteroid regolith as part of future in situ resource utilization for sustained robotic and human space exploration.

¹Michael P.Lucas, ¹Joshua P.Emery, ¹Eric M.MacLennan, ²Noemi Pinilla-Alonso,³Richard J.Cartwright, ⁴Sean S.Lindsay, ⁵Vishnu Reddy, ⁶Juan A.Sanchez, ⁷Cristina A.Thomas, ^8,9VaniaLorenzi
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.12.010]
¹Department of Earth & Planetary Sciences, University of Tennessee, 1621 Cumberland Ave., 602 Strong Hall, Knoxville, TN 37996
²Florida Space Institute, University of Central Florida, Orlando, FL 32816
³SETI Institute, 189 N Bernardo Ave. #200, Mountain View, CA 94043
⁴Department of Physics & Astronomy, University of Tennessee, 1408 Circle Drive, Knoxville, TN 37996
⁵Lunar and Planetary Laboratory, 1629 E University Blvd., Tucson, AZ 85721
⁶Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719
⁷Department of Physics and Astronomy, Northern Arizona University, PO Box 6010, Flagstaff, AZ 86011
⁸Fundación Galileo Galilei – Istituto Nazionale di Astrofisica, Rambla José Ana Fernández Pérez n°7, E-38712 Breña Baja, Spain
⁹Instituto de Astrofísica de Canarias – IAC, C/ Vía Láctea, s/n, E-38205 – La Laguna (Tenerife), Spain
Copyright Elsevier

Spectral observations of asteroid family members provide valuable information regarding parent body interiors, the origin and source regions of near-Earth asteroids, and the link between meteorites and their parent bodies. Asteroids of the Hungaria family represent some of the closest samples to the Earth from a collisional family (∼1.94 AU), permitting observations of smaller family fragments than accessible for Main Belt families. We have carried out a ground-based observational campaign entitled Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record reflectance spectra of these preserved samples from the inner-most regions of the primordial asteroid belt. During HARTSS phase one (Lucas et al. [2017]. Icarus 291, 268-287) we found that ∼80% of the background population is comprised of stony S-complex asteroids that exhibit considerable spectral and mineralogical diversity. In HARTSS phase two, we turn our attention to family members to determine if the Hungaria collisional family is compositionally homogeneous or heterogeneous. We use taxonomic classification, geometric albedo (p_v) estimates, and near-infrared (NIR) spectral properties to infer the composition of the family.

During phase two of HARTSS we acquired NIR spectra of 50 new Hungarias (19 family; 31 background) with the SpeX spectrograph at NASA’s Infrared Telescope Facility (IRTF) and with the NICS spectrograph at the Telescopio Nazionale Galileo (TNG). We analyzed X-type spectra for NIR color indices (0.85-J; J–K), and a subtle ∼0.9 µm absorption feature that may be attributed to Fe-poor orthopyroxene ± the sulfide mineral oldhamite. Surviving fragments of an asteroid collisional family typically exhibit similar taxonomies, albedos, and spectral properties. Spectral analysis of Hungaria family X-types and independently calculated WISE albedos for family members (average p_v=0.403; n=192) is consistent with this scenario. Furthermore, about one-fourth of the background population exhibit similar spectral properties and albedos to family X-types.

Spectral observations of 92 Hungaria region asteroids acquired during both phases of HARTSS uncover a compositionally-heterogeneous background population—including two rare olivine-dominated A-types and one apparent D-type interloper—and spectral homogeneity down to ∼2 km for collisional family members. Taxonomy, albedos, and spectral properties indicate that the Hungaria family progenitor was an igneous body that formed under reduced conditions, and was likely consistent in composition with the enstatite achondrite (i.e., aubrite) meteorite group.

¹M.Ferrari, ¹S.De Angelis, ¹M.C.De Sanctis, ²E.Ammannito, ¹S.Stefani, ¹G.Piccioni
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.11.031]
¹IAPS-INAF, Via fosso del Cavaliere, 100, 00133, Rome, Italy
²Agenzia Spaziale Italiana, Via del Politecnico, 00133, Rome, Italy
Copyright Elsevier

The identification of NH4-bearing phyllosilicates on Ceres poses the question on the NH4-carrier phase(s) and in this study we describe the laboratory production and IR spectroscopic measurements of a suite of ten NH4-phyllosilicates, starting from the corresponding NH4-free minerals. For each mineral, we prepared three types of powder samples: raw (R), ammoniated (A), and leached (L). All samples have been spectrally characterized by means of visible/infrared spectroscopy in the INAF-IAPS laboratories with the FieldSpec Pro in the 0.35-2.5 μm range, and with the FT-IR, using a Vertex 80 spectrometer operating in the range of 2 to 14 µm. The samples were also measured with the SPectral IMager, an imaging spectrometer operating in the spectral range 0.2 – 5.1 µm, which is a replica of the VIR spectrometer on-board Dawn spacecraft. Reflectance spectra of the ammoniated clays show bands near 1.56 μm, 2.05 μm, 2.12 μm, 3.06 μm, 3.25 μm, 3.55 μm, 4.2 μm, 5.7 μm and 7.0 μm that are related to the presence of nitrogen complexes. Treatment of phyllosilicates with ammonia shows that different minerals behave in different ways: NH4+ ions are easily accepted by the smectites, while other non-expandable structures do not accept these ions. The obtained results can be used to better constrain the NH4-bearing species present on Ceres and, possibly, other bodies of the solar system.

¹Mangold et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.11.004]
¹Laboratoire de Planétologie et Géodynamique, CNRS, UMR 6112, Université de Nantes, Université d’Angers, Nantes, France
Copyright Elsevier

From Sol 750 to 1550, the Curiosity rover documented >100 m thick stack of fine-grained sedimentary rocks making up part of the Murray formation, at the base of Mt Sharp, Gale crater. Here, we use data collected by the ChemCam instrument to estimate the level of chemical weathering in these sedimentary rocks. Both the Chemical Index of Alteration (CIA) and the Weathering Index Scale (WIS) indicate a progressive increase in alteration up section, reaching values of CIA of 63 and WIS of 25%. The increase in CIA and WIS values is coupled with a decrease in calcium abundance, suggesting partial dissolution of Ca-bearing minerals (clinopyroxene and plagioclase). Mineralogy from the CheMin X-ray diffraction instrument indicates a decrease in mafic minerals compared with previously analyzed strata and a significant proportion of phyllosilicates consistent with this interpretation. These observations suggest that the sediments were predominantly altered in an open system, before or during their emplacement, contrasting with the rock-dominated conditions inferred in sedimentary deposits analyzed at Yellowknife Bay.

^1,2J. Licandro, ^1,2,3M. Popescu, ^1,2J. de León, ^1,2D. Morate, ^4,1,2O. Vaduvescu,⁵ M. De Prá, ⁶Victor Ali-Laoga
Astronomy & Astrophysics 618, A170 Link to Article [https://doi.org/10.1051/0004-6361/201832853]
¹Instituto de Astrofísica de Canarias (IAC), CVía Láctea sn, 38205 La Laguna, Spain
²Departamento de Astrofísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain
³Astronomical Institute of the Romanian Academy, 5 Cuţitul de Argint, 040557 Bucharest, Romania
⁴Isaac Newton Group of Telescopes, Apto. 321, Santa Cruz de la Palma, Canary Islands, Spain
⁵Departamento de Astrofísica, Observatório Nacional, 20921-400, Rio de Janeiro Brazil
⁶Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching, Germany

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