Using new techniques to examine the products of space weathering of lunar s
oils, we demonstrate that nanophase reduced iron (npFe(0)) is produced on t
he surface of grains by a combination of vapor deposition and irradiation e
ffects. The optical properties of soils (both measured and modeled) are sho
wn to be highly dependent on the cumulative amount of npFe(0), which varies
with different starting materials and the energetics of different parts of
the solar system. The measured properties of intermediate albedo asteroids
, the abundant S-type asteroids in particular, are shown to directly mimic
the effects predicted for small amounts of npFe(0) on grains of an ordinary
chondrite regolith. This measurement and characterization of space weather
ing products seems to remove a final obstacle hindering a link between the
abundant ordinary chondrite meteorites and common asteroids.