A Kinetic Impactor Fleet Sized by Momentum Enhancement: Computed Deflection of a 320-Metre Asteroid

This paper sizes a fleet of kinetic impactors against a 320 m asteroid of density 1,900 kg per cubic metre and mass 32,598,840,890 kg, discovered nine years before a predicted encounter. Each impactor of 1,200 kg strikes at 14,500 m per second and, with a momentum enhancement factor of 3.2 from excavated ejecta, delivers 9.25 mm per second of velocity change at an impact energy of 683.3 GJ. Reaching the required 30.2 mm per second, which corresponds to a 12,000 km displacement, takes 4 impactors, giving a campaign total of 37 mm per second, a margin ratio of 1.23, and a computed final separation of 14,715 km. This is a computed study of a deflection system for planetary defence, with no targeting or weapon application. It is simulated, not measured.