Iran’s paramilitary Revolutionary Guard claimed Wednesday that it had fired what it said were hypersonic “Fattah 1” missiles toward Israel. Simply put, hypersonic weapons are any missile that travels beyond Mach 5, five times the speed of sound. Ballistic missiles, fired high up or outside the earth’s atmosphere, routinely reach this speed.
But in modern warfare, experts say hypersonic weapons must also have advanced navigation systems – making them nimble and capable of changing their trajectory. This can challenge traditional defense systems, said Jack Watling, a senior fellow at the Royal United Services Institute.
Traditional ballistic missiles fly on a trajectory that missile-defense systems like the U.S.-made Patriot can anticipate. Cruise missiles, which can hug terrain, or hypersonic missiles, which are fired to a lower altitude, have less predictable trajectories and are harder to stop.
“Radar can see a missile on a ballistic curve because it’s above the radar horizon. If it’s a hypersonic glide vehicle, it can fly lower and hills get in the way,” Watling said. “That further reduces the time that you will have to engage because if it comes over the horizon, you suddenly see it, and then it’s over.”