Predicted penetration depth for a 1 kg, 10 cm diameter spherical projectile impacting different granular materials, including a bed of glass beads and surface materials similar to what might be found on Phobos, asteroid (101955) Bennu, and asteroid (65803) Didymos. z_stop is the penetration depth, D is the projectile diameter, v_c is the collision velocity, g is the gravity level, ρ_g is the bulk density of the material, and ϕ is the internal friction angle of the material. The shaded regions on the plot show the transition from collision regime I (gray) to collision regime II (blue). The presented model has been tested against numerical and laboratory experiments in this study for collisions in regime II where Fr ≤ 10 (dark blue shaded region), but not for collisions where Fr > 10 (light blue shaded region).