  The formation of the solar system's giant planets predated the ultimate epoch
of massive impacts that concluded the process of terrestrial planet formation.
Following their formation, the giant planets' orbits evolved through an episode
of dynamical instability. Several qualities of the solar system have recently
been interpreted as evidence of this event transpiring within the first ~100
Myr after the Sun's birth; around the same time as the final assembly of the
inner planets. In a series of recent papers we argued that such an early
instability could resolve several problems revealed in classic numerical
studies of terrestrial planet formation; namely the small masses of Mars and
the asteroid belt. In this paper, we revisit the early instability scenario
with a large suite of simulations specifically designed to understand the
degree to which Earth and Mars' formation are sensitive to the specific
evolution of Jupiter and Saturn's orbits. By deriving our initial terrestrial
disks directly from recent high-resolution simulations of planetesimal
accretion, our results largely confirm our previous findings regarding the
instability's efficiency of truncating the terrestrial disk outside of the
Earth-forming region in simulations that best replicate the outer solar system.
Moreover, our work validates the primordial 2:1 Jupiter-Saturn resonance within
the early instability framework as a viable evolutionary path for the solar
system. While our simulations elucidate the fragility of the terrestrial system
during the epoch of giant planet migration, many realizations yield outstanding
solar system analogs when scrutinized against a number of observational
constraints. Finally, we highlight the inability of models to form adequate
Mercury-analogs and the low eccentricities of Earth and Venus as the most
significant outstanding problems for future numerical studies to resolve.
