Laser vs Missile

[Straybow]

Originally posted by Whoha
http://en.wikipedia.org/wiki/Inverse-square_law

Lasers are not governed by the inverse square law. Edge diffraction (and therefore emitter aperature) is the controlling factor.

[Whoha]

Originally posted by Dr Strangelove
The cohesion of laser light is not perfect. In the 1970s there was an experiment conducted by one of the Apollo Moon missions. A laser beam was sent from Earth to the moon and the width of the beam was measured. The beam had spread out considerably, I've forgotten by how much. If the beam spreads out the energy of the beam will also be spread out and its ability to melt through the hull of the enemy craft will be reduced.

too bad they didn't do it from orbit to the moon.

[Straybow]

Originally posted by snoopy369
Laser screens can block a missile, but you don't necessarily need a direct impact to have an effect - large explosions have shock waves that can be very effective as well (and EMP effects, which mean more shielding is necessary, and if you break through some of that shielding...)

Ummmm, no shock wave in space, dude!

[Kuciwalker]

Nuclear warhead.

I anticipated that. It doesn't really matter - currently our power systems favor missiles, obviously, but the context is sci-fi. There's no inherent reason you couldn't power a laser from some future quick-discharge battery (e.g. a capacitor) to give it as much energy as a nuke.

Also the fact that the damage will be spread around the ship, rather then just punching a nice neat hole through it.

That brings up the inverse square law in a bad way - you don't want that feature of missiles. And lasers wouldn't punch through a ship, they'd cause an explosion on the surface (the expanding vaporized surface material absorbs a lot of the laser light, fueling the explosion).

Make a real objection above instead of just "why"ing like a three year old and I'll discuss it.

Nothing you said is necessarily true. If you don't have an argument for it, I'm not going to bother with your posts either.

You're assuming defensive technology does not keep up with offensive technology.

Nothing of the sort.

a) Determining the location of the target: can be made very difficult by stealth technology (or advances beyond that). A laser can't adjust midroute so if you find out you were wrong you have to re-fire.

I'm having trouble imagining a system where a targetting system on a ship would consistently be off by just enough that the missile would be able (with its obviously superior sensors and computational power) to make a correction and end up hitting the target.

b) This can take a lot of processor power, and if we're talking high speed ships with high acceleration why should this be simple?

And clearly more processing power will be available on the missile that's trying to adjust course in real-time to track this target, rather than on the ship that merely has to drive a servo to point a laser?

Also, defensive screens make this more difficult, particularly if they can fluctuate at near-lightspeed also.

WTF is a defensive screen?

c) The hardest/slowest - a laser must be moved, physically, into position. Unless we make a laser that does not require any moving parts, this will always take time. When you're moving at extremely high speeds, this will always be a slowing element.

A missile has to be moved into position too, and the process is far more complex. It's not that hard to predict how long it will take a laser to move into some position, and therefore where we should move it to so it's pointing at the enemy when it's done.

A missile that can adjust mid-flight is faster in all of these categories, assuming it has good maneuvering engines.

The technology that would allow a missile to track at those speeds would allow a laser to do so at least as well.

[Q Classic]

Originally posted by Straybow

Originally posted by Q Cubed
Lasers PEW PEW PEW! Missles FWOOSH!

PCCHHH PCCCHHH PCCHH, shields holding! SWIISSHH, countermeasures fooled teh missile!

BEEP BEEP WRAAAAANG WRAAAAANG!

Quickly, Straybow! Modify the phase variance while I reroute power to the generators!

Someone target the port deflectors!

[snoopy369]

Originally posted by Straybow

Originally posted by snoopy369
Laser screens can block a missile, but you don't necessarily need a direct impact to have an effect - large explosions have shock waves that can be very effective as well (and EMP effects, which mean more shielding is necessary, and if you break through some of that shielding...)

Ummmm, no shock wave in space, dude!

Well, there is if you pack it full of shrapnel

[Whoha]

Originally posted by Kuciwalker

Nuclear warhead.

I anticipated that. It doesn't really matter - currently our power systems favor missiles, obviously, but the context is sci-fi. There's no inherent reason you couldn't power a laser from some future quick-discharge battery (e.g. a capacitor) to give it as much energy as a nuke.

I'll grant that, even though the requirements for a laser that has to survive being shot are somewhat different from a warhead that doesn't, but even if they start out equal the warhead still wins at long distance.

Also the fact that the damage will be spread around the ship, rather then just punching a nice neat hole through it.

That brings up the inverse square law in a bad way - you don't want that feature of missiles.

The energy will be spread a "comparatively" short distance from the ultimate detonation point, which will be the hull of the ship.

And lasers wouldn't punch through a ship, they'd cause an explosion on the surface (the expanding vaporized surface material absorbs a lot of the laser light, fueling the explosion).

that material would be blown into space and away from the target/laser.

[snoopy369]

If you can't imagine defensive technology that would be useful against a laser, Kuci, then you should perhaps consider that your imagination is the issue...

A defensive screen could be any particle or wave that interferes with the function of a laser, applied externally to a ship or other object or location that needs to be defended. You could imagine small metallic dust particles held in place magnetically, that would aid in the dispersion of the laser; hypothesize an interference wave similar to a sound wave (as sound waves can interfere with each other either constructively or destructively) but with light; or even some sort of plating or armor that disperses, reflects, or absorbs the laser in a non-destructive way.

Part of my point is that even if you can't think of it, I would assume some advancement will occur (though perhaps a bit after lasers are powerful, as is normal with defensive technology lagging a bit behind). Who could have imagined self-guided missiles, 150 years ago? Given that real space combat is (unfortunately) probably at least that far off - and technology moving a LOT faster now - I certainly have no belief that I have any idea of the advancements that will occur in the meanwhile

[Patroklos]

While you all are busy argueing about your stupid lasers and missiles, I will crush you all with my mass drivers !

[Q Classic]

You could also imagine shields made of black holes, that just bend the lasers around to a different location. Those shield could be controlled by a crew of defensive specialists manipulating trackballs, and they'd help fight the good fight alongside pilots flying veritech fighters.

[Q Classic]

Originally posted by Patroklos
While you all are busy argueing about your stupid lasers and missiles, I will crush you all with my mass drivers !

There will be hell to pay! The Vorlons will destroy your homeworld, poor Patroklos!

[Patroklos]

The Vorlons will destroy your homeworld, poor Patroklos!

Oh noos!

I do think mass drivers provide the best weapons choice for first generation space combat. Better power in/power out ratio, and the technology is relatively simple.

[Q Classic]

Originally posted by Patroklos


Oh noos!

I do think mass drivers provide the best weapons choice for first generation space combat. Better power in/power out ratio, and the technology is relatively simple.

They're good against stationary targets, but I don't know about smaller, fast-moving ones.

[Sandman]

Originally posted by Kuciwalker
Consider the range you'd need for a laser to possibly miss. Missiles would probably take hours to reach the target at that range.

Dude, unless you're more than several light-seconds away, they can't dodge the laser.

(They can't deliberately dodge the laser anyway - it hits as soon as they see it. They can only constantly juke around to try and foil your aim.

I think it's likely that space combat would take place at very long range, light-seconds or light-minutes apart. Missiles take much longer, it's true and it's already been pointed out that they would be vulnerable to laser defenses.

Stealth missiles are one way round this, but there are others. Dummy missiles, missiles which split into multiple warheads or a cloud of flechettes, or even laser missiles, which close to a range where they can fire off a single use laser blast.

[Kuciwalker]

Originally posted by snoopy369
If you can't imagine defensive technology that would be useful against a laser, Kuci, then you should perhaps consider that your imagination is the issue...

I can imagine defensive technology that you think would be useful against a laser, but I can also debunk all of it. So put up or shut up

A defensive screen could be any particle or wave that interferes with the function of a laser, applied externally to a ship or other object or location that needs to be defended.

.................

Explain how a "wave" would "interfere with the function of a laser". No technobabble please - this may be sci-fi, but I'm not going to accept an argument based on "I can make up whatever magic I want, QED."

You could imagine small metallic dust particles held in place magnetically, that would aid in the dispersion of the laser;

hypothesize an interference wave similar to a sound wave (as sound waves can interfere with each other either constructively or destructively) but with light

That doesn't work with light. Period. Light waves are purely additive; to "interfere" with the laser in such a way to eliminate its effects, you'd need another laser at the same place as the first.

or even some sort of plating or armor that disperses, reflects, or absorbs the laser in a non-destructive way.

Good luck with that. There's no perfect mirror; even if you have a substance with 99% reflectivity, or 99.9% reflectivity, it'd be worthless against a military laser because the reflective surface would be instantly vaporized by the front of the beam and the rest of the energy would be delivered in full. I have no idea what you mean be "dispereses", and "absorbs in a non-destructive way" is impossible - you just said "make uber-massive armor that isn't annihilated by the energy deposited into it by the laser." Such armor would of course be even more effective against a less focused weapon like a missile.

You can't avoid the simple fact that a laser can focus more energy in a smaller area than a missile. Any defensive measure would have to rely on the difference in the character of that energy - that lasers are light whereas missiles are (apart from nukes) kinetic. Unfortunately for you, the only thing that operates differently on those is a mirror, and no mirror could defend against a military laser.

Part of my point is that even if you can't think of it, I would assume some advancement will occur (though perhaps a bit after lasers are powerful, as is normal with defensive technology lagging a bit behind). Who could have imagined self-guided missiles, 150 years ago? Given that real space combat is (unfortunately) probably at least that far off - and technology moving a LOT faster now - I certainly have no belief that I have any idea of the advancements that will occur in the meanwhile

"We don't know what we will invent" does not mean that we can assume that we could invent anything.