Can a planet lose a moon?

The moon formed as the result of a large impact, but was this the first Moon-forming impact? Did Mercury or Venus have Moon-forming impacts like Earth and Mars? Giant impacts are common in many terrestrial planet formation scenarios and most of these impacts would have created a large amount of mass into a disc wrapping around the planet from which a moon would have accreted, yet the frequency of moon formation is unclear. Here, we study the evolution of moons around planets in the context of terrestrial planet formation simulations. From completed numerical N-body simulations of solar system evolution, we extract the collision and flyby history of growing proto-planets. We simulate the formation of a moon after a giant impact, the tidal evolution of the moon as well as the role of gravitational close approaches from temporarily nearby protoplanets. Using these experiments, we explore the competing consequences of each of these different processes and the likelihood for lunar survival.