Space Weathering Change of Grain Surfaces using Meteorite Tests and Related Possible Consequences on Asteroid Properties

Abstract

Compositional and structural understanding of asteroids, especially the moderately small (and frequent) Near Earth Asteroids is important not only for science but also for possible mitigation against their any future impact. However, space weathering substantially modifies the surface infrared spectra, making it difficult to identify their composition. Laboratory tests of artificial weathering by simulated solar wind on meteorites were conducted and reviewed in this study. During the simulations, an increase in the iron content, amorphization, water loss and other structural changes were observed, which usually decreases the mechanical hardness of the very thin surface layer. Using these results, the question was formulated and evaluated here: could such surface changes influence the joint behavior of grain groups when effects driven by YORP forces modify the global shape of asteroids. Based on the evaluation, 10–100 million years of time scale changes are expected to occur both mineral structure and global asteroid shape. The related theoretical consequences and research questions are summarized here.