Regarding Long-Distance Space Combat...
I don't know how far ships can be if they're engaging each other using the aid of sensors that are exclusively speed-of-light or slower (no tachyonic detectors or anything!). I think it depends to a great deal on how easily a ship can move out of its present orbit.
If two ships, 'A' and 'B', were more than a few (let's say, around 10) light-seconds apart from each other, and ship 'A' wanted to scan for and attack ship 'B', ship 'A' might have to use LIDAR to scan for ship 'B'. The problem is that it isn't inconceivable that ship 'B' has technology that detects the incoming ping.
So ship 'B' knows that ship 'A' will, in a couple of seconds, know its position, quite a bit of time before 'A' knows 'B's position, or even its presence. Depending on how advanced 'B's thrusters are, it can change its velocity and orbit to throw off a potential attack (at least until the next ping). If 'A' didn't bother to change its own position and orbit, 'B' might even be able to successfully counter 'A'. At long distances, as seconds increases into minutes, 'B's advantage theoretically grows.
Alternately, ship 'A' might listen for background radiation from ship 'B'. Forgetting things such as any decoy heat and radiation sources that ship 'A' may be employing, ship 'B' learns of ship 'A's position several seconds after the actual event (half the time of the active scanning). This scanning also does't doesn't give away ship 'A's position. However, there are two problems with this situation.
- Ship A is also probably listening for Ship B's radiation.
- Depending on how easy it is for Ship B to change orbits , ship B may or may not be in line with the projected vector by the time the weapon is fired. If it were feasible, ships would probably have to constantly change their velocities and perhaps orbits in order to evade a possible attacker.
It seems that in this case, long-range combat is feasible if it is an ordeal to change orbits (and becomes a 'quick-draw'/MAD type of thing, where the fastest ship or both ships are destroyed), and if convincing decoys have not been developed yet. Potentially ships may travel with cheap, tethered decoys that have their own basic thrusters and emit large amounts of radiation (compared to the shielded reactors of an actual ship).
Both these issues could be counteracted with a 'spray' of fire, either multiple laser beams or railguns targeted towards an area where the ship is likely to be able to move within the time delay. However, as the ships get further apart, that projected area grows in size. As well, depending on how much power these things draw (a lot, by current standards), it may be infeasible to make the weapons very powerful.
They could also be countered with missiles, which would be extremely expensive (relative to the cost of the ship, as they would have to do almost everything a normal ship does) and liable to be shot down by point defenses upon nearing the target.
Therefore, it may be feasible to have relatively close-range combat.
Are there any big holes with my line of reasoning?
Oh, and on a tangent someone mentioned asteroid fields as a way to hide. Unfortunately, that doesn't work quite well, because the actual asteroid density is so small that the enemy would have to be scanning an enormous volume of space.
This post has been edited by UE_Research & Development: 27 August 2006 - 08:01 AM