With respect to the space weapons discussion, I have an alternate suggestion: kinetic weapons. Rail guns.

The problem with missiles is that 1) They require a lot of fuel to accelerate , and all the electronics etc. detract from the payload. 2) A laser point defense, while not exceptional at targeting a distant spacecraft, should do a dandy job of detonating the missile's fuel or messing up the warhead.

A hunk of iron, by contrast, is cheap. The launcher is back on the attacking spacecraft. You can afford to throw a lot more iron than missiles. Also, laser point defense is less useful because even if melted or whatever you're still dealing with a rock of iron on the same vector. It'll still make a kinetic impact with roughly the same amount of force.

Another possibility might be a hybrid -- take a chunk of mass, give it maneuvering jets and guidance for course correction, but still launch it using a mass driver. This allows us to not have to expend a tremendous percentage of the weapon's mass just accelerating it away from the attacking ship, and also makes it less vulnerable to countermeasures.

Of course, the fact that we're dealing with projectiles means that it's hard to hit a target at tactical ranges in space. The solution, then, would be to saturate the target area with a LOT of projectiles. It's not a fool proof solution, but if the target area can be narrowed down enough it should be possible to fire a swarm of projectiles with a reasonable chance of hitting the target. And when we're talking about a projectile moving at a significant fraction of C, you only need one hit to take a target out.

Call it a "meteor swarm" :).

I just don't see missiles -- at least , the kind we now use for air-to-air engagements -- as being that useful in space. It probably won't possess much in the way of fuel or warhead , which means that you're going to need to get it very close to the target to have any effect, and the fact that the target spacecraft likely has more fuel and engines means that it has plenty of time to get out of the way. Assuming it has no point defense. A missile which would be useful might be as large and expensive as a normal spacecraft!

If we develop an interplanetary society, I would not expect that we would continue to reach orbit using chemical rockets. We will be launching into orbit with magnetic accelerators or with skyhooks. I expect our weapons will leverage that same technology, and wars will be fought with mass drivers.

Respectfully,

Brian P.