Sketch of the combined cratering and mass transfer process that occurs during a high-enough velocity collision between a projectile with mass m_p and a target with mass m_t. During the collision, an amount m_mt is added from the projectile to the target, and the rest of the projectile is converted into small fragments with a total mass m_p,frag. An amount m_er is simultaneously eroded from the target, and the final mass of the target is given by .