  Rapid cooling of planetesimal cores has been inferred for several iron
meteorite parent bodies based on metallographic cooling rates, and linked to
the loss of their insulating mantles during impacts. However, the timing of
these disruptive events is poorly constrained. Here, we used the short-lived
107Pd / 107Ag decay system to date rapid core cooling by determining Pd-Ag ages
for iron meteorites. We show closure times for the iron meteorites equate to
cooling in the timeframe ~7.8 to 11.7 Myr after CAI, and indicate that an
energetic inner Solar System persisted at this time. This likely results from
the dissipation of gas in the protoplanetary disk, after which the damping
effect of gas drag ceases. An early giant planet instability between 5 and 14
Myr after CAI could have reinforced this effect. This correlates well with the
timing of impacts recorded by the Pd Ag system for iron meteorites.
