Inspired by The Economist: Testing advanced spacecraft armor against 7+ km/s orbital space junk strikes
In Low Earth Orbit (LEO), space debris travels at orbital velocities averaging 7 to 8 kilometres per second (over 25,000 km/h). At these speeds, a standard structural bolt carries kinetic energy comparable to a detonation of high explosives ($E_k = \frac{1}{2}mv^2$). Traditional solid metallic armor fails because shockwaves propagate directly into satellite pressurized modules, causing catastrophic spallation and rupture.
Modern spacecraft defense relies on the Whipple Shield principle: an outer sacrificial bumper placed 5 to 30 cm ahead of the pressure hull. Upon impact, hypersonic shock pressures exceed the theoretical shear strength of materials (tens of gigapascals), instantly vaporizing and fragmenting the projectile into an expanding, diffuse cloud of molten spray and plasma. This distributes kinetic energy over a wide area, allowing the resilient Kevlar or Nextel rear wall to absorb the residual momentum without breach.