Collisional and Dynamical History of Ida

The history of Ida is constrained by its membership in the Koronis family, its satellite Dactyl, the record of impacts left on its surface, and other dynamical, morphological, and spectral properties. Models of crater production and comparably effective erasure processes, combined with the current size-frequency distribution of craters, suggest that the age of the surface is either about 50 myr or >1 byr. The younger age may be inconsistent with the degraded appearance of many craters, while the older age conflicts with the collisional life expectancy of Dactyl. Consideration of Dactyl's evolution may resolve this issue as well as shed light on the formation of Dactyl, the density of Ida, and possible source regions for Ida and Dactyl within the Koronis parent body.