The LHB in the Outer Solar System
Recent support for an outer Solar System origin for the LHB comes from Iapetus
Saturn System suffered a very heavy bombardment late in life.
- It has suffered ~100X more impacts than we expect from integrating current rates over age of Solar System (Zahnle et al).
- Roughly consistent with Nice model.
- The ejecta blankets of basins overlap equatorial ridge.
- Best model is that the ridge formed as the satellite de-spun (Castillo-Rogez et al. 2007).
- This takes between 200 and 800 Myr!
- The giant planets clear their neighborhood of potential impactors in only 10Myr.