¹Evgeniya V. Petrova,¹Victor I. Grokhovsky,²Anna Kartashova
Icarus (inPress) Link to Article [https://doi.org/10.1016/j.icarus.2026.117147]
¹Ural Federal University, Mira Str., 19/5, 620002 Ekaterinburg, Russia
²Institute of Astronomy RAS, Pyatnitskaya Str., 48, 119017 Moscow, Russia
Copyright Elsevier

Fragmentation, ablation and significant loss of mass occur when the meteoroid passes through the Earth’s atmosphere. There a combined action of melting and shearing takes place, so a fusion crust is forming on the surface of the fragments. It combined a subsurface layer of heated matter and an outer layer consisting of remaining melted meteoroid substance.
In this publication we focused on the process of ablation from different points of view: i – registered spectra of fireballs; ii – fusion crust composition study; iii – ablation modeling ground experiments.

¹Koske Matsubara,¹Yukari Yamaguchi,¹Akiko M. Nakamura,²Sunao Hasegawa,³Takafumi Niihara,^4,5Takehiko Wada
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2026.117135]
¹Department of Planetology, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
²Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan
³Department of Applied Sciences, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama-City, Okayama 700-0005, Japan
⁴National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁵Astronomical Science Program, The Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Copyright Elsevier

The presence of water on the Moon and on asteroids that are thought to be poor in water, either because they formed inside the snow line or because they lost much of their water during differentiation, has been suggested by multiple studies; however, its form and origin remain unclear. In this study, we conducted hypervelocity impact experiments between serpentinite projectiles and steel targets. Serpentinite contains hydroxyl and simulates hydrated impactors such as primitive asteroids. The effects of impact velocity and angle on the survival and form of water delivered to the target surface were investigated using near-infrared reflectance spectroscopy and microscopic Raman spectroscopy. Reflectance spectra of projectile materials adhered to the crater surfaces suggested that, in all head-on impact experiments with velocities of 3–7 km s−1, hydroxyl pre-existing in the projectile was almost completely lost. The spectra also showed olivine absorption features at shock pressures exceeding ~80 GPa, and the olivine Raman peaks became narrower at higher impact velocities. Based on the comparisons with results from impact experiments with anhydrous projectiles, it is suggested that molecular water can be trapped in the melt at shock pressures below ~100 GPa. In contrast, in the oblique impact experiments conducted in this study, decomposition of projectile material was suppressed, and hydroxyl was detected in crater samples. The current results, along with comparisons to impact velocities of asteroids in the main belt and on the Moon, suggest that molecular water derived from hydrated impactors can be detectable through spectroscopic observations.