  It has been suggested that the ejection to interplanetary space of
terrestrial crustal material, accelerated in a large impact, may result in the
interchange of biological material between Earth and other Solar System bodies.
In this paper, we analyze the fate of debris ejected from Earth by means of
numerical simulations of the dynamics of a large collection of test particles.
This allows us to determine the probability and conditions for the collision of
ejecta with other planets of the Solar System. We also estimate the amount of
particles falling-back to Earth as a function of time after being ejected. We
find that, in general, the collision rates of Earth ejecta with Venus and the
Moon, as well as the fall-back rates, are consistent with results reported in
the literature. By considering a larger number of particles than in all
previous calculations we have also determined directly the collision
probability with Mars and, for the first time, computed collision probabilities
with Jupiter. We find that the collision probability with Mars is greater than
values determined from collision cross section estimations previously reported.
