  We consider the history of New Horizons target (486958) Arrokoth in the
context of its sublimative evolution. Shortly after the Sun's protoplanetary
disk (PPD) cleared, the newly intense sunlight sparked a sublimative period in
Arrokoth's early history that lasted for ~10-100 Myr. Although this sublimation
was too weak to significantly alter Arrokoth's spin state, it could drive mass
transport around the surface significant enough to erase topographic features
on length scales of ~10-100 m. This includes craters up to ~50-500 m in
diameter, which suggests that the majority of Arrokoth's craters may not be
primordial (dating from the merger of Arrokoth's lobes), but rather could date
from after the end of this sublimative period. Thereafter, Arrokoth entered a
Quiescent Period (which lasts to the present day), in which volatile production
rates are at least 13 orders of magnitude less than the ~10^24 molecules/s
detection limit of the New Horizons spacecraft (Lisse et al. 2020). This is
insufficient to drive either mass transport or sublimative torques. These
results suggest that the observed surface of Arrokoth is not primordial, but
rather dates from the Quiescent Period. By contrast, the inability of
sublimative torques to meaningfully alter Arrokoth's rotation state suggests
that its shape is indeed primordial, and its observed rotation is
representative of its spin state after formation.
