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.

¹Vladimir Svetsov,¹Valery Shuvalov,¹Dmitry Glazachev,¹Olga Popova,¹Natalia Artemieva,¹Elena Podobnaya,¹Valery Khazins
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14329]
¹Sadovsky Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russia
Published by arrangement with John Wiley & Sons

We completed numerical simulations of a number of asteroid and comet impacts on Earth to predict related shock wave and thermal radiation effects and to estimate seismic effects, as well as ionospheric disturbances. Using interpolation of the results, we were able to estimate these effects for arbitrary impact parameters. In addition, we used previously developed models to estimate the size of the impact crater and ejecta thickness. Finally, we developed a user-friendly web-based calculator (https://asteroidhazard.pro/) that quickly estimates shock wave pressure and radiation exposure at a given location, as well as crater size and average ejecta layer thickness, if any, seismic magnitude, change in ionospheric density, and some other values. The input parameters of the calculator are the impactor diameter and density, its speed and inclination angle of the trajectory above the atmosphere, and the coordinates of the observer (the point on the ground where it is necessary to determine the impact consequences). This paper describes the methods of numerical simulations and techniques for approximating the results. We present a few examples of how to assess the impact hazard, in particular, overpressure and wind speed on the surface, thermal radiation, and seismic shaking after a crater-forming impact or an airburst in the atmosphere.