Feasibility of kinetic orbital bombardment

In this paper, the possible impact effects of orbital bombardment systems and their feasibility are studied. These effects are the projectile penetration into concrete and steel targets and seismic effects. The equations of motion for the re-entry of a projectile and the penetration were solved numerically. The projectile penetration is modelled using the Alekseevskii–Tate model. By varying the altitude (h), projectile length (L), manoeuvre velocity (ΔV) and the target properties, the flight time (t), earthquake magnitude (M) and penetration depth (P) are calculated. The calculations show that the impact of a tungsten alloy rod with a length of 8 m and a 0.4 m diameter results in an earthquake with a seismic magnitude of only 2.5 on the Richter scale. For concrete, the optimal result is obtained for a projectile with a length of 0.56 m. It penetrates 1.79 m with a minimal ΔV trajectory. These results show that a kinetic orbital bombardment system is not feasible without major technological developments, the impact angle being a bottleneck of the concept. Moreover, one has to accept very high costs. Without any means to change the attitude of the projectile, using ICBMs or bombers shows a better penetration performance than re-entry. Weapons in orbit may provide a strategic advantage. However, they are restricted by international space laws. Impact angle of the projectile is a bottleneck for kinetic orbital bombardment. Larger impact angles can be achieved, but at the expense of a larger mass-to-orbit. A hypersonic drag device may be used to optimise the impact angle and thus improve the system. Alternative projectile delivery methods (Bomber, Intercontinental Ballistic Missile (ICBM)) show better performance for both steel and concrete targets. Essentially, only penetration phenomena matter because the seismic effects are not significant. Therefore, orbital bombardment systems don’t even resemble weapons of mass destruction (WMD). Given their limited effect, destroying a particular target requires a guidance and flight control system, which, given the high velocities, may not be feasible.