Post-battle debris concerns
I'd say it's insignificant for one missile, yes, but hundreds or thousands of missiles multiplied by battle after battle might eventually add up to something serious. Note that since they're c-fractional, they don't even have to remain explosive -- they'll do major damage with the impact.
And no, I wouldn't expect them to be dangerous for ships. I was thinking planets. The probabilities (even assuming similar planes-of-orbit and so on) for hitting even a planet are infinitesmal, and the size of a ship adds even more orders of magnitude.
But your point about the tech secrets is even better.
I think you're all worrying about the wrong debris problem!
Yeah, a 120 ton missile body hitting a populated world would be a pain in the ass, but that's nothing: think about what would happen if, say, a three million ton chunk of shattered superdreadnought should hit some planet at .1-.2c either immediately after or a couple centuries after some major battle!
Granted, there are more missiles flying about after a battle than wrecked starships, but look at Third & Fourth Yeltsin - there would be tens of wrecked SDs and BBs scudding about.
(OK, yeah, it's a *really* low-probability event, but non-zero.)
True. Which is one of the reasons that a standard post-battle task for the winning side in an inhabited star system is to plot [any] substantial pieces of debris, and to take steps to ensure that any dangerous chunks aren't going to wind up landing in Protector Benjamin's flower garden. Or someplace equally unpleasant.
This is one of those routine operations which I've never mentioned because it wasn't really particularly germane to what I was doing, but perhaps I should go ahead and to a scene -- or possibly a short piece for one of the anthologies -- which deals with the problems of cleaning up after a naval battle in
From a post to ALT.BOOKS.DAVID-WEBER dated July 17, 2002:
You would have to posit some mechanical failures of significance to just [lose] a missile.
Mechanical failures of significance happen in battle. A near miss from a point defense laser that burns out the missile's sensors without actually destroying the missile... a nuclear warhead (or ship's fusion plant) exploding far enough off that the missile's out of range of the actual fireball, but catches the EMP... these kinds of things could easily soft-kill a missile, prevent it from ever engaging, but not actually do serious structural damage to it.
I would certainly expect missiles that have lost guidance from the launch vessel to either call for help or go into some kind of self directed attack mode even if it was less effective.
All missiles go into self-directed attack modes. I believe the ship's fire control turns them loose shortly after launch so that it can handle the next salvo, but certainly once they get into attack range, the seekers in the missiles themselves take care of the final target acquisition. However, that doesn't help if the missile never makes it into attack range of a real ship because it's off chasing an EW ghost, or never even sees an actual target because of massive jamming.
Actually, it is true that only a relatively small number of missiles fail to expend themselves when launched at a target. Most of those which "miss" actually detonate and waste their attack against the wedge or sidewall of the target vessel.
There certainly are missiles which completely fail to "see" their targets, of course, and it is true that this has been on the increase with the combination of the advances in electronic countermeasures and the extreme ranges at which missiles can now be launched. The EW capability increases would account for a good bit of that all by themselves, but the sheer range -- with the attendant decreases in sensor reliability and the enlarged time window in which the intended to target can move to a totally different place make the problem even worse.
None of the navies in the Honor Harrington universe is really particularly concerned about the possibility that one of their errant missiles is going to impact on another starship or a planet at some distant point in the future. The assumption is that it would be extremely unlikely simply because of the smallest of the target and the vast area in which said target lies, and that it is far more probable the missile is going to destroy itself by running into a sufficiently solid objects (or series of very small objects... like, say, grains of sand) that it is to hit the target anyone cares about. However, more appropriate to the topic of debate in this thread, is the observation someone made that no one wants a "lost" missile being recovered by the other side and analyzed, and no one wants to have one of his own missiles overshoot and enemy task force and detonate in close proximity to a friendly task force which is closing in on the enemy from the other side. Accordingly, all missiles in the Honorverse are equipped with self-destruct software which is routinely set before the weapon is launched. There are fairly standard parameters for the settings, the most common of which is simply to set the warhead to self-destruct on a "time-from-launch" basis which would take it well beyond any flights time at which it could possibly engage it intended to target before it blows itself up.
In short, there are not shoals of missiles flying around the depths of interstellar space seeking life-bearing planets to immolate.
Does make an interesting sort of mental image, though, doesn't it?