  A large disruption in the main asteroid belt can cause a large flux, an
"asteroid shower", on the terrestrial planets. We quantitatively examine the
hypothesis that such an event was the cause of the lunar late heavy bombardment
(LHB). We performed numerical integrations of about 20000 test particles
starting in the vicinity of the nu6 secular resonance in the main asteroid
belt. The purpose of these integrations is to calculate, for each of the
terrestrial planets, the collision probability of asteroids coming from an
asteroid break-up event in the inner part of the main belt. Compared with
previous studies, we simulate nearly two orders of magnitude larger number of
particles, and we include the orbital effects of the eight planets, Mercury to
Neptune. We also examined in detail the orbital evolution of asteroid fragments
once they enter the Earth's activity sphere, including the effect of the
Earth-Moon orbit. We obtained the collision probability, the distributions of
impact velocities, impact positions, and impact angles of asteroid fragments on
the Moon. The collision probability with the Moon (~0.1%) suggests that a
fairly large parent body, 1000-1500 km in diameter, is required if the LHB
event is to be ascribed to a single asteroid disruption. An even larger parent
body is required for less favorable initial conditions than we investigated
here. We conclude that an asteroid disruption event is not a viable explanation
for the LHB.
