¹Radek Novotný, ^1,2Gunther Kletetschka, ³Filip Košek, ⁴Daniela Popelková
Icarus (in Press) Open Source Link to Article [DOI: 10.1016/j.icarus.2026.117299]
¹Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Faculty of Science, Charles University, Prague, Czech Republic
²Geophysical Institute, University of Alaska Fairbanks, United States of America
³Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Prague, Czech Republic
⁴Imaging Methods Laboratory, BIOCEV, Vestec, Czech republic
Copyright Elsevier

This study investigates the response of lunar breccia minerals and selected reference materials to accelerated Ga⁺ ion irradiation using focused ion beam (FIB) processing combined with Raman spectroscopy. Anorthite and pyroxene bearing clasts from Apollo 15 breccias 15405 and 15445 were examined alongside monocrystalline silicon, magnetite, and pyrite to evaluate mineral specific structural modifications induced by heavy ion exposure. Samples were characterized by Raman spectroscopy before and after irradiation with 30 keV Ga⁺ ions at four beam currents (0.43, 0.79, 2.5, and 9.3 nA). Silicate phases exhibited band broadening, peak shifts, and partial amorphization consistent with increasing lattice disorder. Monocrystalline silicon showed progressive damage of the crystalline structure, while magnetite and pyrite displayed enhanced structural disorder and modifications of Fe-bearing spectral features. At the highest irradiation conditions, Ga implantation and local heating may have contributed to the observed changes. Based on published SRIM-derived displacement estimates, the maximum Ga⁺ fluence applied in this study corresponds to approximately 10⁵–10⁶ years of natural solar wind exposure in terms of cumulative atomic displacement damage. This estimate is intended only as an approximate comparison between laboratory irradiation and natural space weathering. Although Ga⁺ FIB irradiation does not directly reproduce natural solar wind conditions, it provides an accelerated approach for assessing the relative susceptibility of planetary materials to heavy ion induced structural degradation and offers implications for future spectroscopic and paleomagnetic investigations of lunar samples.

^1,2Peter Jenniskens, ¹Stuart Pilorz, ²Darrel Robertson, ^2,3Eric C. Stern
Meteoritics & Planetary Science (in Press) Open Source Link to Article [DOI: 10.1111/maps.70203]
¹SETI Institute, Mountain View, California, USA
²Asteroid Threat Assessment Project, NASA Ames Research Center, Moffett Field, California, USA
³Hyperspace Technologies, Inc., Mountain View, California, USA
Published by arrangement with John Wiley & Sons

How does the energy deposition profile (light curve), deceleration, and penetration depth in Earth’s atmosphere depend on asteroid composition and meteorite type? Here, we present the light curve and velocity profile of 75 bolides from camera-documented meteorite falls. The light curves as a function of altitude generally develop in the following seven phases: Phase (1) an initial rapid brightening; (2) a gradual increase that sometimes shows periodic brightness variations; (3) an onset and rapid increase of brightness until reaching a plateau; (4) a plateau with occasionally chirping brightness oscillations; (5) flares that result in fragments in the meteor wake; (6) an end flare of sometimes different color; and (7) ongoing ablation and fragmentation until dark flight. These seven phases are interpreted as resulting from solid bodies that cause early brightness oscillations from meteoroid spin, a plateau because of melting and reaching melting equilibrium, chirping oscillations due to plasma instabilities, flares due to fragmentations along fractures from dynamic pressure and thermal stress, and an end flare when the surviving back of the meteoroid explodes. This paper discusses the systematics of how the phase heights depend on entry speed, entry angle, initial mass, and meteorite type. The dynamic pressures during the onset of fragmentation and the end flare correlate with the tensile strength of the recovered meteorites. The results have implications for Planetary Defense when anticipating the energy deposition curve of small solid-body airbursting asteroid impacts like Chelyabinsk.