Creative ways to alter an ICBM's flight path post-launch
January 20, 2014 10:19 PM   Subscribe

From what I understand, there is no way to alter a Minuteman III missile's course once it has launched, other than someone shooting it down. But in theory, if someone had had secret access to the missile itself at some point before the launch, could they install something that might be able to alter its flight path during the boost phase, in some manner?

(It's for a story, so please feel free to spitball as long as it's somewhat in the realm of the possible.) Thanks!
posted by np312 to Technology (17 answers total) 4 users marked this as a favorite
You could alter the missile's trajectory during the boost phase, however after the boost phase the warheads are ballistic, meaning they don't manuver, but stay on a parabolic flight path to the target. Its kinda hard, I think. Wikipedia has a lot on this.
posted by Ironmouth at 10:35 PM on January 20, 2014

You could alter it before the launch, even just before. This is called 'retargeting'. Most plausibly that alteration would be at a high level, such as changing it's target to a different one. Any low-level alteration of the physical controls of the missile would essentially be random screwing with it, and who knows where it would land after that.

I don't know about a Minuteman specifically, but I doubt if it has the capability to retarget in flight. It would have to be done before leaving the launch platform. (since position of the launch platform determines control inputs to target)

After the boost phase, like Ironmouth says, it's a flying rock. It lands where you threw it.
posted by ctmf at 11:07 PM on January 20, 2014

It's true that the missile is ballistic once the boost phase is done. However, in a MIRV missile what get's launched is a carrier (which is actually known as a "bus") with multiple warheads. When it gets over the target area, it turns to point to the first target, and fires one warhead, then turns to another, and fires another warhead.

That phase could be altered. But only to the extent of shifting a warhead from one target to another relatively nearby. (How far? I think that answer is classified, but probably on the order of a few dozen miles.)
posted by Chocolate Pickle at 11:16 PM on January 20, 2014 [1 favorite]

Best answer: You could assume a steerable warhead bus - either aerodynamically, or with some small (shuttle-like) thrusters, which the hero/bad guys use to control it post boost.

Otherwise, yes, obviously it is steerable by autopilot during the boost phase to ensure it tracks as planned. But as ctmf says, to take control and issue other instructions would have to be on the basis that it is overriding the autopilot which thinks that it should be going somewhere else - or the autopilot has been told it is going somewhere other than where the military think it it is supposed to be going.

However, as we are talking fiction here, no reason why in that world retargeting is not possible while in flight, which would be a neater way of doing it.
posted by GeeEmm at 11:17 PM on January 20, 2014

If you're writing a story that involves changing the missile, just make up how they did it. The information always given to us is coming from a source that would love us to believe that their missile is infallible. Perhaps they're lying to serve their own interests. Don't feel limited just because it's said that the missile is immutable.
posted by ZaneJ. at 3:25 AM on January 21, 2014

if someone had had secret access to the missile itself at some point before the launch, could they install something that might be able to alter its flight path during the boost phase, in some manner?

At a basic level, sabotage could cause the rocket to fail during the boost stage thereby most likely causing it to fall far short of its target. It depends how much "secret access" they have but draining or tainting/damaging the fuel in the second or third boost stages would certainly "alter its flight path" but if you're talking about actively altering/controlling it, that's a different kettle of fish.
posted by wackybrit at 4:01 AM on January 21, 2014

I imagine the missile would have a powerful gyroscope to keep it aerodynamically balanced. Something to interfere with that? A powerful secondary gyroscope to wobble in the cone?
posted by dances_with_sneetches at 4:48 AM on January 21, 2014

You do not have to effect the missile. The guidance system works off the global positioning satellite system, Navstar. That is the same GPS system that civilians use. If that system was altered, the missile might think it is hitting one place, when in fact it is hitting another.

Navstar has several layers of back-up, and it is operated by the Dept of Defense. So, altering that system would be extremely difficult. But, altering Navstar would cause the missile to alter course.
posted by Flood at 6:07 AM on January 21, 2014

Rather than going after the electronics, I would have your perpetrator plant some sort of explosive charge that would damage the fins (or whatever the correct term is) so that the missile would be physically unable to change its trajectory.

This would render it unable to hit its intended target. If you want to specifically choose a different target, then this would not work for you.
posted by DWRoelands at 6:25 AM on January 21, 2014

The guidance system works off the global positioning satellite system, Navstar.

I'm pretty sure this is wrong. These missiles need to be absolutely foolproof. It would be relatively easy for an enemy to knock out GPS satellites. You don't make your nation's nuclear deterrent that vulnerable.
posted by Dasein at 6:34 AM on January 21, 2014 [2 favorites]

This is one way it was done in a story.
posted by three blind mice at 8:29 AM on January 21, 2014

Best answer: Supposing ICBMs really do only rely on GPS.

A little light research reveals that the US has plans to upgrade systems to M-code, their next gen military GPS signal. M-code has a dependency on GPS OCX which is not fully in production yet (according to Wikipedia anyway). It seems likely that the Minuteman III must also be upgraded. It's the government, so it probably takes forever and is shitty.

The feature set of GPS OCX suggests to me that the current military GPS signal must be cryptographically weak, and therefore could hypothetically be exploited by planting something inside the missile before launch. See GPS spoofing for more details.

Or, perhaps a trusted engineer at Raytheon plants a firmware exploit during system upgrades for M-code.

But in either case, in real life it's almost impossible that anyone would fire that thing off and not be tracking it with other external monitoring systems. So the second it starts going off course, there is probably a procedure in place to intercept. They are not going to let a nuclear missile hit something else than what they are shooting at. I really hope, anyway.
posted by tracert at 9:36 AM on January 21, 2014

If the gyroscopes is a real thing, are they made out of metal? Could your character install an electromagnetic device with a remote that he could activate in flight to change the course?


Have you ever played Angry Birds? Translating their flight path into missile terminology, what would you call the device that causes your finger-press to make the bird suddenly speed up or split into 3 smaller birds or drop an egg? Could your character install something like that?


I know I've seen movies/TV where a missile does not just simply fall in a parabola. I've seen them fly horizontally about 4 feet off the ground, go up stairs and around corners. Is that complete fiction? Because I could totally believe that someone could hack into that guidance system and redirect the missile to its own path. Look at the DARPA engineers who hacked into the computer of a Toyota Prius to see a real-life analogy. Depending on the sophistication of your intended audience, you could totally get away with that.
posted by CathyG at 10:48 AM on January 21, 2014

Best answer: Hmmm. Depending on how plausible this needs to be, I could imagine something involving a directed EMP burst that would either scramble or (less plausibly) reprogram the missile's guidance electronics in flight. Perhaps somebody could position a microwave laser in the missile's path somewhere near the end of the boost phase which would fry the electronics and cause the engines to either stay on too long or cut off too soon, causing the warhead to either overshoot or undershoot its target. Of course, chances are that in reality the missile would be much too high and moving much too fast for this to actually be doable, and I would have to assume that the electronics are shielded in some way so as to prevent this kind of interference.

Alternatively, maybe you could interfere with the warhead itself on the way down. What if you could, say, position a drone aircraft exactly in its flight path such that the warhead crashes through the plane as it descends? Maybe this would take away enough of the warhead's momentum and/or deflect it enough that it would land somewhere else. This would rely on your having precise information about the missile's course early enough to be able to get an object in the way, naturally.
posted by Scientist at 1:03 PM on January 21, 2014

Best answer: The conventional way of destroying an ICBM in development is to crack the booster with explosives. The thing that does it is called a range safety system. It's for SRBs whose combustion chamber is integral to the fuel. MX had one. The shuttle SRBs had one, IIRC. i've lost track of what has what, but if it's solid fuel, it had one in development. on deployed rockets, they are usually not a feature.... if you launch it, you're done. no going back and who gives a shit if milwaukee is accidentally vaporized?

( i once submitted a cost reduction proposal to not test and ICBM stuff. my reasoning was that if you ever had to launch it, whether or not it worked was moot. so why bother testing. the mere chance it would work was deterrent enough. the managers, they did not like my humor. i did. fukm.)

In storable liquid propellant rockets, like Titan II, thrust vectoring mechanisms provided boost phase control. Interfere with that.... in any way that changes the control rules... left=right kinds of wiring.

Adding drag sufficient to overcome boost phase steering might work, too.

I don't know what's in MIRVs that gives them positional awareness, but star tracking was one way some spook satellites know their attitude and position. if your story provides pre-launch access, you could blind such a thing. these rockets are exo-atmospheric, you know? no clouds to get in the way if star tracking is what they use to know where they are before SAR and warhead release.

the mods killed my observations earlier that the ballistic missiles (early titans and early minuteman) were CEP 100 meter capable and MX was rumored to be 10 or less CEP. you don't have to interfere much to make a big down range difference.
posted by FauxScot at 2:05 PM on January 21, 2014

ballistic missiles (early titans and early minuteman) were CEP 100 meter capable and MX was rumored to be 10 or less CEP. you don't have to interfere much to make a big down range difference.

For hardened targets that may be so, but for cities etc you would need to shift the impact point at least tens of kms, preferably a hundred or more if the aim (!) was to save them. If we are talking of a shift from target x to target y, that implies a shift of hundreds or even thousands of kms, which would be beyond terminal guidance (a la MIRV) - the greater the shift, the earlier in the missile's flight it needs to commence.
posted by GeeEmm at 5:46 PM on January 21, 2014

Best answer: With respect to someone having access to the missile before launch, have you heard of the Project SCORE satellite launch in 1958? (Previously on metafilter)

The night before the launch one engineer modified the Atlas rocket on the pad, including disabling the rocket-fuel cut-off and faking the sensor data. Immediately after launch the rocket veered "off course", but the range-safety office knew about the true mission and let it continue so that it would achieve the proper orbit to release the shortwave radio transmitter.
posted by autopilot at 8:08 PM on January 21, 2014

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