  Giant planet migration appears widespread among planetary systems in our
Galaxy. However, the timescales of this process, which reflect the underlying
dynamical mechanisms, are not well constrained, even within the solar system.
Since planetary migration scatters smaller bodies onto intersecting orbits, it
would have resulted in an epoch of enhanced bombardment in the solar system's
asteroid belt. To accurately and precisely quantify the timescales of
migration, we interrogate thermochronologic data from asteroidal meteorites,
which record the thermal imprint of energetic collisions. We present a database
of 40K-40Ar system ages from chondrite meteorites and evaluate it with an
asteroid-scale thermal code coupled to a Markov chain Monte Carlo inversion.
Simulations require bombardment in order to reproduce the observed age
distribution and identify a bombardment event beginning 11.3 +9.5/-6.6 million
years after the Sun formed (50% credible interval). Our results associate a
giant planet instability in our solar system with the dissipation of the
gaseous protoplanetary disk.
