Sea-skimming anti-ship missiles — such as the Exocet of Falklands War fame — have worried navies since the 1970s:
What’s changed is the speed of anti-ship missiles. Older weapons such as the Soviet Styx and America’s Harpoon were subsonic, which meant they were slow enough to be jammed or shot down by shipboard anti-missile systems such as the U.S. Navy’s Phalanx multi-barreled cannon. Newer weapons, such as Russia’s P-270 Moskit and Kh-31, could achieve supersonic speeds of Mach 3 or 4 that taxed anti-missile defenses.
But a new generation of Russian and Chinese hypersonic anti-ship missiles — like Russia’s Zircon, with an estimated speed of Mach 6 to 9 – are a different matter. They both fly low and move fast.
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“As opposed to ballistic missile trajectories where Navy guided missile destroyers and cruisers have on the order of several minutes to detect, track, lock onto, and then launch interceptors against a hypersonic reentry vehicle, low flying missiles provide as little as 10 seconds of flight time above the ship’s radar horizon before missile impact,” the Navy explains.
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Drones are a prime candidate for hosting an airborne missile detection radar. “The most obvious candidate aircraft to host the radar system would be on high altitude long-endurance (HALE) and medium-altitude long-endurance (MALE) unmanned aircraft,” according to the Navy.
But even with better radar detection, the physics of hypersonic weapons will still vex the defenders. The high speeds of hypersonic missiles flying through the atmosphere generate plasma clouds that absorb radar waves. “Even when a threat vector is identified so as to constrain the radar surveillance volume, the detection and tracking timeline for single or multiple inbound missiles whose radar return may be buried within a plasma envelope is extremely challenging,” the Navy notes.
A sea skimming missile flying in the dense atmosphere just above the waves at several times the speed of sound is going to get hot — very hot.
Everyone already has heat-seeking technology.
And something traveling so fast is going to be very susceptible to damage by anything it hits.
A heat seeking missile which blows out a blast of ball bearings in the path of the oncoming hypersonic missile (a flying Claymore mine, so to speak) and the problem is over.
Now that reported Chinese ship-killing nuclear missile — that would be a real problem!
As Gavin said, it’s not going to be doing Mach 5+ whilst sea-skimming. The damn thing will melt.
You can get to, maybe, the top end of Mach 3 while down on the deck and even that not for long; that’s the limit of the material science.
The issue of then getting the weapon seeker to function through a white-hot sheaf of plasma is left as an exercise for the attentive reader.
It’s drones that are the game changer, and we’ve fallen behind. The Turks [!] are in the lead now globally, and in demand.