Determine the converged return-impact history and outcome

Determine a numerically converged return-contact time for the bound-companion pathway and establish the outcome of the second hydrodynamic impact, including whether the returning refractory survivor is incorporated into Titan while preserving or augmenting the icy reservoir.

Background

The bound-companion pathway models a differentiated companion that collides obliquely with Titan, releases ice, and may later return for a second encounter. A 0.25-Titan-mass companion in the 45-degree case reaches an illustrative compact-body contact after 6.9 years, while alternative numerical continuations from the same state avoid contact for 50 years. The simulations stop before a second hydrodynamic merger, so they do not establish either a robust return date or the physical consequences of the return impact.

References

The calculations establish return possibilities, but neither a converged 45$\circ$ contact date nor the second impact's outcome.

— A Collisional Origin for Ice-rich Iapetus and Titan's Anomalous Eccentricity  (2609.28948 - Mosqueira, 24 Sep 2026) in Section 3.2, subsection “Initially bound companions: ice release and return encounters”