  The orbital architecture of the Solar System is thought to have been sculpted
by a dynamical instability among the giant planets. During the instability a
primordial outer disk of planetesimals was destabilized and ended up on
planet-crossing orbits. Most planetesimals were ejected into interstellar space
but a fraction were trapped on stable orbits in the Kuiper belt and Oort cloud.
We use a suite of N-body simulations to map out the diversity of planetesimals'
dynamical pathways. We focus on two processes: tidal disruption from very close
encounters with a giant planet, and loss of surface volatiles from repeated
passages close to the Sun. We show that the rate of tidal disruption is more
than a factor of two higher for ejected planetesimals than for surviving
objects in the Kuiper belt or Oort cloud. Ejected planetesimals are
preferentially disrupted by Jupiter and surviving ones by Neptune. Given that
the gas giants contracted significantly as they cooled but the ice giants did
not, taking into account the thermal evolution of the giant planets decreases
the disruption rate of ejected planetesimals. The frequency of volatile loss
and extinction is far higher for ejected planetesimals than for surviving ones
and is not affected by the giant planets' contraction. Even if all interstellar
objects were ejected from Solar System-like systems, our analysis suggests that
their physical properties should be more diverse than those of Solar System
small bodies as a result of their divergent dynamical histories. This is
consistent with the characteristics of the two currently-known interstellar
objects.
