A few years ago Steven Den Beste remarked that the characteristics of ships and their weapons have always dictated naval strategy and tactics, but science-fictional space ship battles are unsatisfying because the characteristics of space ships and their weapons don’t seem to dictate space strategy and tactics.
When I first read his essay, I hadn’t read much “hard” science fiction — I still haven’t, really — so I was largely unaware of the simple notion that there ain’t no stealth in space. In the vacuum of space, any ship with a crew is a 290-Kelvin flare. With its engines running, it’ll be hard to miss from even further away — and it will continue on a perfectly predictable trajectory until it fires those engines again. In fact, by comparing the energy given off by the engines to the ship’s acceleration, observers can even deduce the ship’s mass — and thus whether it’s a real ship or a decoy.
All this talk of infrared radiation brings up another point: space ships need enormous, vulnerable radiators. There are only three ways of getting rid of heat — convection, conduction, and radiation — and the first two don’t work in a vacuum. Yes, the vacuum of space is cold — but not because it’s full of cold matter. Without enormous radiators, any ship running its engines should melt in minutes.
So, our space ships trivially spot one another at enormous distances, following perfectly predictable trajectories. Each ship is vulnerable to a simple gun shot, unless it expends tremendous delta-V to change trajectory — putting itself on a new, perfectly predictable trajectory.
Ships probably won’t shoot simple unguided projectiles though; they’ll shoot guided missiles, which should be impossible to out-accelerate and dodge.
But you don’t have to dodge a missile if you can destroy it with point-defense lasers. It’s hard to say how easy that will be, but another alternative is to fry its electronics with a microwave laser, or maser, turning it into an unguided projectile, which can be dodged.
It’s not much like WWII in space.