The vast network of orbital railguns that dot Earth's orbit are the planet's last line of defense and most powerful shield. Able to fire 2-pound tungsten rounds at a marginal percentage of the speed of light, these railguns can be used either for planetary defense or for precision strikes at tactical targets. Throughout the various seasons of The Expanse, the United Nations has used these weapons before, both to strike at key MCRN assets and to disable asteroids on a collision course with Earth.