Solar wind as the origin of rapid reddening of asteroid surfaces

Asteroids are much 'redder' than meteorites (which come from asteroids); the accepted explanation is 'space weathering', though the actual processes and timescales involved have remained controversial. Vernazza et al. report observations of two young asteroid families, revealing that 'space weathering' must be a very rapid process, which favours solar wind implantation as the main mechanism; they further demonstrate an apparent weathering dependence on olivine abundance.