Swindle1984 wrote:Shit, we could do it now, if we devoted money and resources to it. We could be building O'Neil Island 3 cylinders, and from there it's not a huge leap to designing a Rama-style interstellar STL generation ship. Projects NERVA, Orion, and Daedulus gave plausible means of propelling ships that massive for huge distances. Just set up a generation ship that could sustain a sizable population for a few centuries and launch it at the nearest star system. There, you've just launched an invasion of another star system with technology ranging anywhere from late 20th century to late 21st century.
By the time we had enough experience with the design constraints involved, I think we'd be far enough ahead of our current level of knowledge in space
engineering, if not raw science, that calling us "late 20th" or even "early 21st" century would be quite disingenuous.
We'd have a lot to learn, you see...
Also, the resulting colony ship would not be very well militarized... which, come to think of it, is exactly the context where the alien invasion becomes most interesting.
Destructionator XIII wrote:Simon_Jester wrote:Arguably not. "There is no militarily useful stealth in space" is equivalent to "there is no stealth in space" as far as most non-pedants would be concerned.
Ah, there exists one situation where it might not work, and therefore it is
never useful. Logical.
If the situation in question is "any time you're fighting any war you might actually wind up fighting," then yes, stealth is not useful.
I still can't come up with a context in which it's all that helpful to send my spaceships coasting ballistically for months before they make their attack run in order to avoid detection.
Another place where it might be useful: in your space fighters. The other guy's anti-fighter system probably isn't as sensitive as the telescopes pointed at interplanetary fleet bases, probably has a lot more shit to deal with, and doesn't have a chance to dwell.
...What, precisely, is an "anti-fighter system?" Is the plan to launch small parasite craft (missile buses are arguably better candidates than 'fighters' in the classical sense, but that's not an attempt to contradict you) from long range, let them do their acceleration burns at equally long range, and then have them coast into range of the target?
The problem with that is that the parasite craft will have to get in a lot closer, because it
can't mount laser cannon capable of frying things from a million miles away, not in the near-future technological context you seem to be invoking. Which means getting correspondingly close to the enemy's passive (and active!) sensors.
Also, the enemy parasite-carrier's launches will still be detectable unless, once again, you launch from so far out that you have very few guarantees of your target still being there, unalerted, by the time you hit it.
The stealth only has to be good enough to defeat what the other guy is actually using. Hell, not even defeat it, just enough to give you a little tiny edge.
If the enemy still sees you coming with plenty of lead time to start lobbing things at you, exploiting his inherent defensive advantage of having more tonnage of weapons and defenses and sensors than you can mount on highly mobile platforms, the stealth doesn't do a lot of good.
among other things, because it gives the enemy too long to notice your fleet has mysteriously gone missing via other channels.
Yup, that kind of thing is always a problem. Odds are the other guy will know an attack is coming, but when, exactly, is it going to arrive? Are you going to sit at battlestations for a week or more on end?
Beats a lethal dose of X-rays, no?
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I would think it a routine precaution to keep telescopes trained on enemy fleet bases over interplanetary distances, myself.
Even if it works, the other guys are just going to accept this? Here's a few things that might break it:
a) Can they make out the specifics at the other base? Is that flash normal civilian traffic or a military fleet? How big is the fleet?
b) Where are they heading, exactly? Do they want to hit New York or are they going for Ontario?
Does it matter? I can get the fine details of where your ballistic stealth ship is headed by launching a space probe to do a flyby mission past it and ping it with lidar from a few thousand kilometers.
All I really need to know is
that you launched something, and approximately where in the sky it is to be found. I can nail down the details to get fire control telemetry afterwards, and most of your countermeasures will require the ship to go active and shoot back... which defeats the purpose of the stealth mission in the first place and may well result in the destruction of your ship.
c) How many telescopes do you have pointed to it? It's easy to say infinite, but that isn't realistic. If the enemy were to arrange a piece of space junk to fly in front of your telescope for a while, would this ruin things?
I would think that two or three Hubble-equivalent telescopes (for redundancy) would be cheaper than a base for interplanetary spacecraft. Assuming the opposition has a comparable budget and technical base, or even a slightly inferior one, they can watch your bases at a much lower investment of resources than you put them in.
X-ray FELs are also power-inefficient by nature,* and warming them up to fire is a nontrivial task that will be difficult to complete if you're trying to fire snap shots from ambush.
Question: does the other guy have it any better? It takes the attackers 20 minutes to warm up... but it takes the defenders 25. With the perfect info the "no stealth" assumes, it doesn't matter, they have plenty of time. With limited info, this gives them 5 minutes of pounding with no way to respond.
That works in a quick-draw competition, in principle. Problems:
-The enemy has resupply from his own base, and may be able to afford the luxury of keeping a few weapon systems continuously ready to fire, or ready to fire on very short notice. Thus, you're trying to beat someone to the draw when their weapon is already in their hand.
-The enemy may have emergency defense measures that can be enacted quickly and that interfere with your attack,
other than shooting back- Such as a radical thruster burn to throw off targeting, which is a problem even for light speed weapons at the ranges you invoke).
-The enemy may well spot you from so far out that they warm up their weapons far in advance- a major risk if they are clever and have mobile recon assets.
Stealth can, in theory, confer a major advantage, with luck. But on the other hand it comes at a high cost:
-Stealth ships take much more time to travel to the target.
-Stealth ships cannot make evasive maneuvers while in flight without going active, which makes it difficult for them to avoid threats even if they see those threats coming (such as a recon probe that's going to fly within a few thousand kilometers of their position).
-Stealth ships cannot react as quickly to a
sudden crisis, because of the need to power up systems that were kept powered down during the ballistic phase.
-The effectiveness of the stealth attack is directly proportionate to how unprepared and ill-equipped the enemy is in terms of sensor capabilities. An opponent of comparable capability can probably counter your stealth ship with assets much less expensive than the ship was.
To make this attack cost effective, you're pretty much restricted to firing ballistic missiles rather than ballistic spaceships that themselves carry launchers for powerful weapons.
