Deep penetration of projectile material into the planet during the impact

A mechanism through which water could be buried inside the Moon is found. If an icy comet strikes the planetary surface and a thin natural crack exists at the site of the impact, some amount of cometary material can penetrate deep into the ground. This happens due to peculiar features of hydrodynamic flow along the crack. Numerical simulations based on the free-Lagrangian method show that the amount of water buried under the crater is several percent of the original mass of the projectile.