Why does a 50-meter meteorite create a 1.2-kilometer-wide crater? Understanding hypervelocity impact hydrodynamics and crater scaling laws.
1. The 3 Phases of Crater Formation
1. **Contact & Compression**: Hypervelocity impact generates megabar shockwaves, vaporizing both projectile and target rock.
2. **Excavation Stage**: Shockwave decompression ejects billions of tons of rock upward and outward, opening a transient cavity.
3. **Modification Stage**: Gravitational collapse of transient walls widens the crater, producing flat floors or central rebound peaks.
2. Schmidt-Holsapple Impact Scaling Formula
Used by Asteroid3D's physical calculator:
$$D_{crater} = 1.161 \left( \frac{\rho_i}{\rho_t} \right)^{1/3} D_i^{0.78} v_i^{0.44} g^{-0.22} (\sin \theta)^{1/3}$$
3. Arizona Meteor Crater Case Study
A ~50-meter metallic nickel-iron impactor traveling at 12.8 km/s blasted a 1.2 km wide, 170m deep crater in under 10 seconds.