Soil maturity and planetary regoliths - The Moon, Mercury, and the asteroids

Observations of the Moon, Mercury and the asteroids provide data which can be used to assess current ideas about the optical maturation of regoliths of bodies without atmospheres. Telescopic data show Mercury's surface to be as optically mature as the Moon's while the asteroids appear to have 'fresh' surfaces. We suggest that these cases illustrate two different paths of regolith evolution caused by differing micrometeoroid impact velocities, gravity, and in some cases composition.