Simulation of space weathering on asteroid spectra through hydrogen ion and laser irradiation of meteorites

Space weathering can be defined as the combination of physical and chemical changes that occur in material exposed to an interplanetary environment on the surface of airless bodies. This process produces amorphous surface layers often containing small opaque particles such as nanophase metallic iron (npFe0). This darkens the topmost layer resulting in alterations in material spectroscopic features.Eventually it can lead to misinterpretation of remotely sensed data in the visible- near-infrared (VIS-NIR) spectrum. The goal of this research is to simulate solar wind effects on asteroid spectra through low energy 1 keV hydrogen ion irradiation of meteorite powder samples and measure the changes in their reflectance spectra. This allows to understand how space weathering depends on the mineralogy of the material. We used Bjurböle (L/LL4), Avanhandava (H6) and Luotolax (Howardite) meteorites. H+ ion irradiation was carried out on powdered samples compressed into pellets. The pellets were placed into a vacuum chamber with pressure between 1.2 x 10 -7-2.4 x 10 -7 mbar for the whole experiment. To simulate solar wind irradiation, H+ ions were used with 1 keV under three fluences; 1 x 1017, 2 x 1017 and 5 x 1017 ions/cm2. Subsequently reflectance spectra of the samples were measured and processes using Modified Gaussian Model (MGM) to derive key spectral parameters. Both chondrites show significant reddening in the VIS region. Bjurböle being an LL, it is more oxidized than Avanhandava. The reddening in the NIR region is more significant in Avanhandava than in Bjurböle. My work indicates that even for low-energy solar wind conditions, the chondritic materials (Q/S-type asteroids) with high olivine content and/or higher fayalite (Fa) compositions are more susceptible to silicate absorption bands reduction. Luotolax meteorite being howardite rich in orthopyroxene and clinopyroxene, shows VIS reddening but not observable band depth changes with increasing exposure to H+ ion irradiation. The smaller change in Luotolax may be due to higher pyroxene resistance to low-energy ion irradiation. Overall, at short timescales and typical solar wind energies, VIS slope reddening is the most dominant factor in all three material compositions

Simulating asteroid impacts and meteor events by high-power lasers : from the laboratory to spaceborne missions

Meteor plasmas and impact events are complex, dynamic natural phenomena. Simulating these processes in the laboratory is, however, a challenge. The technique of laser induced dielectric breakdown was first used for this purpose almost 50 years ago. Since then, laser-based experiments have helped to simulate high energy processes in the Tunguska and Chicxulub impact events, heavy bombardment on the early Earth, prebiotic chemical evolution, space weathering of celestial bodies and meteor plasma. This review summarizes the current level of knowledge and outlines possible paths of future development.Czech Science FoundationCzech Academy of Sciences Program of Regional Cooperatio

Simulation of Space Weathering on Asteroid Spectra through Hydrogen Ion Irradiation of Meteorites

Space weathering can be defined as the combination of physical and chemical changes that occur in material exposed to an interplanetary environment on the surface of airless bodies. This process results in alterations in material spectroscopic features. Eventually, it can lead to misinterpretation of remotely sensed data in the visible-near-infrared wavelength range. This study simulates the solar wind effect on asteroid spectra through low-energy 1 keV H+ irradiation of meteorite pressed-powder samples under three fluences, 2 x 10(17), 5 x 10(17), and 1 x 10(18) H+ cm(-2), and evaluates changes associated with reflectance spectra. The meteorites subjected to the study are Bjurbole (L/LL4), Avanhandava (H4), and Luotolax (howardite). The most prominent changes in all three meteorites are (1) a decrease of 550 nm reflectance, (2) reddening in the 1 mu m region, and (3) a monotonous decrease in absorption band strengths in Bjurbole. No significant changes were observed in the 2 mu m region. The results imply that at short timescales (10(2)-10(3) yr), radiation damage as amorphization and vesicle formation caused by low-energy solar wind is the dominant space weathering factor in all three meteorite compositions, causing spectral changes predominantly in the 1 mu m region.Peer reviewe

Simulating asteroid impacts and meteor events by high-power lasers : from the laboratory to spaceborne missions

Peer reviewe

Simulating asteroid impacts and meteor events by high-power lasers: from the laboratory to spaceborne missions

Peer reviewed: TrueMeteor plasmas and impact events are complex, dynamic natural phenomena. Simulating these processes in the laboratory is, however, a challenge. The technique of laser induced dielectric breakdown was first used for this purpose almost 50 years ago. Since then, laser-based experiments have helped to simulate high energy processes in the Tunguska and Chicxulub impact events, heavy bombardment on the early Earth, prebiotic chemical evolution, space weathering of celestial bodies and meteor plasma. This review summarizes the current level of knowledge and outlines possible paths of future development.</jats:p