Oscar
Moderator
No - that is a different tracking problem.
Everyone talks about BrahMos and other supersonic cruise missiles like they’re these perfect Mach‑3 death darts, but the guidance part at those speeds is absolutely brutal.
At Mach 2+, you cover 2 kilometers in what…6 or 7 seconds? That’s all the time your onboard radar has to lock, figure out where the target actually is, and correct whatever navigation drift you’ve built up on the way in.
Now imagine the missile’s a few hundred meters off course when the seeker finally wakes up. That’s a massive cross‑track error to fix when you’re moving faster than a rifle round. BrahMos and similar missiles have those little reaction thrusters around the body, but it’s just a single ring of them and not multiple layers like you see on highly agile short‑range missiles. So they’re not meant for constant fancy maneuvers. It’s basically a one‑shot nudge: “Oh crap, I’m half a kilometer left lets yeet some gas, pivot, and hope the fins can tidy things up.”
GNSS spoofing still messes with missiles even if they’ve got fancy terminal seekers: the seeker only kicks in near the end. For most of the flight, the missile’s navigation stack depends on inertial measurement plus satellite updates to stay on course. If your GNSS feed gets spoofed or jammed, that inertial drift just keeps building. By the time the seeker wakes up, it might be staring at open ocean instead of the target area. Even if it does get a lock, the geometry might force the missile into a terrible intercept angle or outside its thruster authority.
A fun part btw
Ballistic missiles actually care less about GNSS interference during most of their flight. Once they boost out of the atmosphere and follow that gravity‑driven ballistic arc, their path is pretty predictable. The INS alone can keep them accurate enough over long distances when using modern ring‑laser or fiber‑optic gyros that drift only a few meters per minute. GNSS updates help fine‑tune midcourse alignment, but even if you jam or spoof them mid‑flight, the missile’s already coasting on a mostly ballistic trajectory; the main error source is in the initial launch alignment, not mid‑flight guidance. Long story short: spoofing hurts precision but usually won’t make it miss completely.
Supersonic cruise missiles, though, depend on GNSS far more. They’re flying in thick atmosphere the whole way, at low altitude, pulling navigation fixes constantly to stay on a curved, terrain‑following route. Their INS drifts a lot faster because every gust, turn, and vibration introduces more cumulative error. Without periodic GNSS corrections, that drift can easily mean missing the target area by hundreds of meters—or even kilometers—by the time the seeker is supposed to take over. And remember, the seeker only activates in the final few kilometers, so if spoofing convinced the missile it was somewhere else, the seeker might just wake up looking at nothing.
INS can try to correct that with terrain‑matching algorithms (TERCOM‑type logic) or radar altimeter cues, but that takes processing power, stored map data, and time that may not fully compensate for a false positioning baseline. So for a supersonic cruise missile, reliable GNSS is like a lifeline; for a ballistic one, it’s more of a nice‑to‑have midcourse tweak.
