@article{a63852956899435081c12a9105b95d66,
title = "STXM-XANES analyses of Murchison meteorite samples captured by aerogel after hypervelocity impacts: A potential implication of organic matter degradation for micrometeoroid collection experiments",
abstract = " The Tanpopo mission is an astrobiology space experiment at the Japanese Experiment Module (JEM) 'Kibo' on the International Space Station (ISS). One of the sub-divided themes of the Tanpopo mission is for the intact capture of organic bearing micrometeoroids in low Earth orbit using ultralow density silica aerogel (0.01 g/cm 3 ). In order to evaluate damage to organic matter in micrometeoroids during hyper velocity impacts into the aerogel, Murchison meteorite powdered samples, analogs of organic bearing micrometeoroids, were fired into flight-grade silica aerogel (0.01 g/cm 3 ) using a two-stage light-gas gun with velocities of 4.4 and 5.9 km/s. The recovered Murchison grains were analyzed using scanning transmission X-ray microscopy/X-ray absorption near edge structure (STXM/XANES), transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS). TEM observation did not show significant modifications of the recovered Murchison grains. Carbon-XANES spectra, however, showed a large depletion of the organic matter after the 5.9 km/s impact, but no such effects nor any significant hydrogen isotopic fractionation were observed after the 4.4 km/s impact.",
keywords = "Impact, Meteorite, Micrometeoroid, Organic matter, Tanpopo mission",
author = "Yoko Kebukawa and Kyoko Okudaira and Hikaru Yabuta and Sunao Hasegawa and Makoto Tabata and Yoshihiro Furukawa and Motoo Ito and Aiko Nakato and {David Kilcoyne}, {A. L.} and Kensei Kobayashi and Yokobori, {Shin Ichi} and Eiichi Imai and Yuko Kawaguchi and Hajime Yano and Akihiko Yamagishi",
note = "Funding Information: Acknowledgments—The authors thank Dr. Keiko Nakamura-Messenger (JSC/NASA) for her instructions in the sample sulfur-embedding method. We thank anonymous reviewers for helpful comments. The two-stage light-gas gun experiments were supported by ISAS/JAXA as a collaborative program with the Hypervelocity Impact Facility (former name: Space Plasma Laboratory). STXM-XANES data were acquired at beamline 5.3.2.2 at the ALS, which is supported by the Director of the Office of Science, Department of Energy, under Contract No. DE-AC02-05CH11231. This work is supported by Japan Society for the Promotion of Science KAKENHI (grant number JP15K17794, JP17H02991, JP17H06458, JP18K03722, 26287142), the Astrobiology Project of the Center for Novel Science Initiatives (CNSI), National Institutes of Natural Sciences (NINS) (Grant Number: AB271015, AB281004, AB291005, AB301020), and the Shimadzu Science Foundation (2016). Publisher Copyright: {\textcopyright} 2019 by The Geochemical Society of Japan.",
year = "2019",
doi = "10.2343/geochemj.2.0549",
language = "English",
volume = "53",
pages = "53--67",
journal = "Geochemical Journal",
issn = "0016-7002",
publisher = "The Physiological Society of Japan",
number = "1",
}