  With the successful impact of the NASA DART spacecraft in the
Didymos-Dimorphos binary asteroid system, we provide an initial analysis of the
post-impact perturbed binary asteroid dynamics. To compare our simulation
results with observations, we introduce a set of "observable elements"
calculated using only the physical separation of the binary asteroid, rather
than traditional Keplerian elements. Using numerical methods that treat the
fully spin-orbit-coupled dynamics, we estimate the system's mass and the
impact-induced changes in orbital velocity, semimajor axis, and eccentricity.
We find that the changes to the mutual orbit depend strongly on the separation
distance between Didymos and Dimorphos at the time of impact. If Dimorphos
enters a tumbling state after the impact, this may be observable through
changes in the system's eccentricity and orbit period. We also find that any
DART-induced reshaping of Dimorphos would generally reduce the required change
in orbital velocity to achieve the measured post-impact orbit period and will
be assessed by the ESA Hera mission in 2027.
