¹Takaaki Noguchi,¹Akira Miyake,²Hikaru Yabuta,³Yoko Kebukawa,⁴Hiroki Suga,⁵Makoto Tabata,⁶Kyoko Okudaira,⁷Akihiko Yamagishi,^8,9H. Yano
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14327]
¹Division of Earth and Planetary Sciences, Kyoto University, Kyoto, Japan
²Department of Earth and Planetary Systems Science, Hiroshima University, Hiroshima, Japan
³Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan
⁴NanoTerasu Promotion Division, Japan Synchrotron Radiation Research Institute, Sendai, Miyagi, Japan
⁵Faculty of Science, Chiba University, Chiba, Japan
⁶Division of Information Systems and Aizu Research Center for Space Informatics (ARC-Space), Department of Computer Science and Engineering, University of Aizu, Fukushima, Japan
⁷Department of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
⁸Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
⁹Space and Astronautical Science, Graduate Institute for Advanced Studies, SOKENDAI, Sagamihara, Kanagawa, Japan
Published by arrangement with John Wiley & Sons

The Tanpopo experiment is Japan’s first astrobiology mission aboard the Japanese Experiment Module Exposed Facility on the International Space Station. The Tanpopo-1 mission exposed silica aerogel panels to low Earth orbit from 2015 to 2016 to capture micrometeoroids. We identified an impact track measuring approximately 8 mm long, which contained terminal grains in the silica aerogel panel oriented toward space. The impact track exhibited a bulbous cavity with two thin, straight tracks branching from it, each preserving a terminal grain at their ends. The terminal grains were extracted from the silica aerogel and analyzed using scanning transmission electron microscopy and scanning transmission X-ray microscopy to investigate their X-ray absorption near-edge structure (STXM-XANES). Both grains are Fe-bearing and relatively homogeneous orthopyroxene crystals (En88.4±0.4 and En88.2±1.8). The recovery of Fe-bearing low-Ca pyroxene aligns with previous studies of micrometeoroids captured in LEO. Micrometeoroids containing Fe-bearing olivine and low-Ca pyroxene are likely abundant in LEO.