Physically plausible explanation for missile based space combat?

[GTOM]

If the missile steers around semi-randomly, then there's no way for a laser to know where to aim.

But the laser arrives almost instantly, well focusing the beam to a single location is more troublesome, the first countermeasure against it is spinning.

 

[novaprime]

Fire them electromagnetically with a rail gun style system. The missile wouldn't be hot, no friction or exploding gases to eat them. The missile passively scans for the target emitting nothing trackable. When the missile decides it's close enough to the target it activates its own stored fuel and accelerates to a much higher velocity for a short burn. Think it it as throwing a bullet before it self ignites. If it misses it just stays dark.

The idea that it's silent and undetectable till it's too close to dodge. After all if the missile isn't seen to can't be targeted by lasers. If you want the missile could start using whatever radar equivalent you want on final approach. And since you said most your fights are going to be in the asteroid belt, there's plenty of junk to clutter up attempt to find the missiles.

-Oh and railguns are real, the military already has several experimental models that work. They're just not practical at the moment.

 

[GTOM]

Fire them electromagnetically with a rail gun style system. The missile wouldn't be hot, no friction or exploding gases to eat them. The missile passively scans for the target emitting nothing trackable. When the missile decides it's close enough to the target it activates its own stored fuel and accelerates to a much higher velocity for a short burn. Think it it as throwing a bullet before it self ignites. If it misses it just stays dark.

The idea that it's silent and undetectable till it's too close to dodge. After all if the missile isn't seen to can't be targeted by lasers. If you want the missile could start using whatever radar equivalent you want on final approach. And since you said most your fights are going to be in the asteroid belt, there's plenty of junk to clutter up attempt to find the missiles.

-Oh and railguns are real, the military already has several experimental models that work. They're just not practical at the moment.

But won't the electromagnetic flux heat up the projectile, or the gun itself, that heats the missile?
(Otherwise i think, they will use active radars as well against cold projectiles.)

 

[Ryan_m_b]

Presumably the action of a rail gun firing would be noticeable and the missile would be hot as it leaves the tube (might not be any air resistance but the magnetic force is going to add heat). Given that it seems like it would be trivial to have your tactical awareness software plot the speed and course of the missile. Even if it cooled to the background temperature of space and was perfectly radar invisible your computer would know where it is. If you've got laser weaponry accurate to within thousands of kilometres you could destroy it long before it became an issue.

 

[newjerseyrunner]

If I were living in the not too distant future, where missions to Mars / moon / asteroid belt are common, but no starships yet, I'd build my weapons entirely in space, maybe a single launch to send up some advanced computers that can't be produced on site. It would also be very simple in design, if I had automated drones producing them, I'd want them pumped out quickly, that way if half of them get destroyed on their way to the target, many still hit and they'll be so destructive, I'd win anyway.

Think about NORAD. Right now, it's impenetrable. It was designed so that the Soviet Union could pummel it with nuclear weapons and it would stay standing. The energy of the bomb is reflected off of the mountain. It's literally in the heart of a mountain, no nuke or antimatter bomb could affect it.

A million tons of steel hitting the mountain a hundred thousand miles an hour is a different story. My war machine would orbit the Earth very high, maybe even orbit the moon. The guidance system, controls... everything would be deep inside millions of pounds of iron that's been harvested from asteroids. Containing a powerful, liquid hydrogen and oxygen rocket, using water also gathered from space. Your lasers wouldn't be able to cut through that, even the atmosphere couldn't destroy it. It's so heavy that by the time it's detected and can be shot at, even the most powerful weapons would only shove it a little off course, and it's shell would protect the guidance system, allowing it to correct pretty much up until it enters the atmosphere and can't navigate anymore. Once it's hit the atmosphere, it'll obliterate anything it hits.

KE = mv^2, double the speed, quadruple the yield.

 

[Ryan_m_b]

In most space warfare fiction the combatants are quite distant. If that's the case then conventional weapons seem rather useless. Unguided kinetic weapons can be easily tracked and dodged, guided weapons shot when they're in range, beam weapons might not be able to be tracked but minor random course changes would make it extremely unlikely to be hit at range.

The issue then is that combatants would have to get close to fight. Let's say they have beamed weapons: the closer they are the more real time their information is and the likelier your laser will hit the target. But that works both ways, getting closer means your enemy is more likely to hit you.

Enter the combat drone. It's basically a laser weapon with guidance systems. You launch a bunch of these towards your enemy (could launch them quite fast then have them use their propulsion as needed) and along the way they make minor course changes to avoid fire from the defender. The closer they are the more often they figher at the target. You might loose a few but with enough you should hit your target without exposing your own ship.

Of course the best defence against this would be to launch your own drones back. Battles in this case would comprise of ships staying well outside each other's effective weapon range sending waves of drones at each other. Where those drones clash you hope your weapons and software is good enough to ensure you've still got a large enough force heading towards the target.

A notable limitation is that space is vast. If your fictional technology verges on the hard science those drones aren't going to be carrying enough fuel to go long distances fast (more fuel might help but increases weight so slows acceleration). So there's a window of engagement where it makes sense to launch drones, closer than that you open yourself up to fire and further away your drones will take to long to get there and the enemy could just run away.

 

[GTOM]

You wouldn't care about coherence, intensity and data transmission rate limit the range.

Neglecting small prefactors, the angular spread of a laser beam is at least (wavelength)/(telescope radius). At a distance of d, the laser beam has a width of d times the angle, so the fraction of light hitting the receiver is $$\left(\frac{(receiver~radius) \cdot (telescope~radius)}{distance \cdot wavelength}\right)^2$$

I have tryed to do the math.
Had the following results so far :
so assume 10 MW reactor for 100 ton ship (yeah i know not diamond hard... that applies to the rest as well, but i want to have it something common with reality)
25 km/s exhaust velocity. (e^2 mass ratio for 25km/s for rocket with deceleration)

Calculate with base mass for simplicity : 0,032 kg / s mass ejected from rocket.
800 pushing power 0,008 m/s2 acceleration.

Reach full speed during 40 mil km (so constant speed up and down till Mars when it is closest to Earth) during a month, so two-three month from Earth to Mars.

Laser power only MJ/sec.
10m focusing mirror (while a 100m mirror sounds good, but keep it cool after multiple shots...)

At a 1000 km able to focus at 3cm with 300nm UV-B laser.

10% efficiency versus (SF) titan-mirrorium armor.

Around 2000 C for melting titan armor.
1MJ/10/2000 mol titan, 100g.

So a 3cm spot 3cm thick, it is more than 100g

So to kill the striker craft with a single shot distance smaller than 1000km needed.

30km closing speed for fighter (25+5 save 5 for return in case of intercepting a not so well defended convoy)
during that, laser could burn 3kg titan, and even if striker craft shatters, shrapnels still quite dangerous.

(Assumed 1 arcmin spread. With 30m rocket cross-section, 1/100 of mass would hit, and it is enough...)If mothership would like to support landed troops with laser, with atmospheric swallow, and 100m mirror, and much bigger output... I think it still needs to be closer than 100.000 km to efficiently attack armored targets, so get into a range, where it can be attacked even from surface launched missiles.

 

[Artribution]

Thermonuclear missiles, when detonated, flood local space with such extreme levels of heat, light, EM waves and particle radiation that sensors are effectively jammed, rendering an enemy blind and helpless. A swarm detonation of such weapons around an enemy formation can maintain the sensor-blinding effect continuously, putting even a large fleet out of action. Humans have a term for the sensor-jamming effect: nuclear blackout.

 

[GTOM]

Thermonuclear missiles, when detonated, flood local space with such extreme levels of heat, light, EM waves and particle radiation that sensors are effectively jammed, rendering an enemy blind and helpless. A swarm detonation of such weapons around an enemy formation can maintain the sensor-blinding effect continuously, putting even a large fleet out of action. Humans have a term for the sensor-jamming effect: nuclear blackout.

I still don't like the idea that every goon would throw nukes in space. I think a good kW laser jammer could do the sensor black out thing, or at least reduce targeting accuracy.

https://books.google.hu/books?id=ANEM6nI3tosC&pg=PA196&lpg=PA196&hl=hu#v=onepage&q&f=false

According to it, skirt jamming (jam with not exactly same frequency) could require 60dB jamming/signal or more. That is a million times more than the signal.
So at a distance of 10.000km if reflected or emitted signals are scattered well (inverse squre law) it could be able to do the trick. If lots of probes emitted, use the lidars shaded from enemy jammers to find them.

Probably striker craft should be UFO shaped? (spin, and a sharp edge at the middle, to scatter the beams more)

 

[Artribution]

Well, in this scenario, I don't have any idea how the enemy's scanning devices work. But a nuclear blast (or many nuclear blasts) is generally good because the intensity and wide range of emissions interferes with almost everything, from masking a spacecraft 's heat signature to interfering with radar waves and magnetics. On top of that, it destroys unshielded electronics. And blackout is a known effect in nuclear strategy, so it's good if you want something non-speculative.

Another thing worth mentioning is that nuclear warheads can be improved by sheathing them in different materials that add to their effects. For example, they could be made to scatter radar-absorbing particles over a wide radius for improved jamming efficiency, and such particles could linger for some time.

 

[Ryan_m_b]

If you're close enough to deploy nukes and shine jamming lasers on their sensors you're close enough to kill them, or be killed by them. It's difficult to have these sorts of discussions without a setting to discuss it in, complete with available technology.

 

[GTOM]

If you're close enough to deploy nukes and shine jamming lasers on their sensors you're close enough to kill them, or be killed by them. It's difficult to have these sorts of discussions without a setting to discuss it in, complete with available technology.

I think i gave much info with my calculations, but i gladly give more, what would you like to know?
At this point, while i don't know too much about sensors or astronomy, i don't clearly see why the jamming range has to be so close to kill range, they don't have to exactly focus on the sensors.
With a distance of thousands of kms, and inverse square to the signals, i would think it is like blind someone with a reflector, who has a night-vision google. Burn the skin require much bigger power.

 

[Artribution]

If you're close enough to deploy nukes and shine jamming lasers on their sensors you're close enough to kill them, or be killed by them. It's difficult to have these sorts of discussions without a setting to discuss it in, complete with available technology.

Nukes (call them fusion disintegrators if you want to be all sci-fi) can be launched from as far away as another planet. The final stage could be very small and very hard to track without an engine burning, and the stage before that could actually serve as a useful decoy. I agree we can't really come to a decision without some understanding of the technologies available, but we can speculate about physically plausible explanations.

 

[GTOM]

The final stage could be very small and very hard to track without an engine burning, and the stage before that could actually serve as a useful decoy. I agree we can't really come to a decision without some understanding of the technologies available, but we can speculate about physically plausible explanations.

Interesting idea, that stage as a decoy, yes launch range is near unlimited vs stationary target.

So, summarize things.

Basic setup : prolonged war for the asteroid mines, with multiple parties, (privateers included) I would say at at least hundred years have passed since they started to colonize other celestials.

Technology available : everything that exists now + fusion rockets (i gave details about them in calculations post) i think it would be illogical not to have at least a MJ output laser with so much power on board, some new alloys (the titan-mirrorium armor i talked about) hibernation (manned spacecraft not much more expensive than unmanned, general distrust in decision making AIs due to one party's cutting edge in robotics, hacking) drone fighters, neural interfaces (human factor still worth mentioning in drone operating) advanced high-thrust low specific impulse drives for striker craft (I can think about nuclear-thermo)

Most likely war situations are attacking cargo convoys (with frigates and privateers) and overtake mines (that is cover based combat)
I think even cargo ships should have lidars against a meteor (even if a hit is an unlikely event) and shielded electronics vs cosmic rays.
Restrictions : orbital bombardment of settlements is war crime (while Earth's gov is pretty corrupt, they won't overlook that one - that would mean even politicans couldn't be safe) I barely see any reason why would employing nukes were a different category.

 

[Artribution]

I don't see why using nukes in space would necessarily be considered a war crime. We're talking about combat between military spacecraft . Would anyone care if they blew each other up with nuclear missiles instead of photon torpedoes? It's the same result either way: a big flash of light ensues, and the offending spacecraft disappears.

Also, thermonuclear devices have all kinds of applications for asteroid mining.

And your story reminds me of a highly underrated classic.

 

[GTOM]

I don't see why using nukes in space would necessarily be considered a war crime. We're talking about combat between military spacecraft . Why would anyone care if they blew each other up with nuclear missiles instead of photon torpedoes? It's the same result either way: a big flash of light ensues, and the offending spacecraft disappears.

Also, thermonuclear devices have all kinds of applications for asteroid mining.

And your story reminds me of a highly underrated classic.

Thanks for the link, sounds interesting. :) (Although now i don't really have time for gaming.)
Use nuclear bombs for mining? Isnt it a problem, that the sorroundings will be contaminated by really nasty isotopes? Otherwise in my setting in majority of cases mining corps war against eash other too (i would describe it space feudalism)

Still, let's have a megaton explosion at the distance of 10.000 km. So energy released is on the order of 10^15 J. Apply inverse square law, 10^7m, 10^14 on square, so energy density on ship will be around 10J/m2.
If a 20 KJ jamming laser focus on whole ship with 30m diameter density will be around 30J/m2. And it can be operated in continuous mode. (The point would be turn off everything but the crudest sensors not much more sensitive than human eye, to cause targeting problems).

Even if the nuke is total black, and even have liquid helium vs IR detection, if the enemy has any guess about attack direction, they can send some small probes forward, and detect the shadow of the nuke.

 

[Artribution]

But:

1. A laser will only jam a target's light and heat sensors. Sensors that work on other principles would be unaffected.
2. If the jammed target is part of a larger formation (a fleet of manned spacecraft or just one spacecraft with a surrounding network of drones) the jamming laser and its source will be visible to them.
   
3. If the jammed target is in contact with the other nearby spacecraft (or drones) as part of a tactical computer network, it's possible even the 'jammed' spacecraft could ignore the jamming by using another spacecraft 's sensors.
4. A laser would have more limited range than a swarm of missiles and (unlike a missile) firing a laser requires getting close enough to expose your own spacecraft to risk.
5. A missile can evade, unlike a laser.
6. A missile can go around asteroids and dwarf planets, unlike a laser.
7. A missile swarm can shut down their engines and act as an orbiting minefield.
8. Missiles have a continuous mode, too—we call it launch all the missiles.
   
9. Near-future technologies might very well allow a small missile to be practically invisible (active camouflage) and transparent to radar/EM/laser detection (plasma stealth). Those are both areas of active research.
10. If jamming lasers are so much better, is there any reason a missile can't carry a short-range laser of its own, along with other ECM?

 

[Ryan_m_b]

A missile cannot evade a laser point defence at close range. It can randomly change course and junk but the closer it gets the smaller the envelop of possible locations it could be in, thus more chance that a laser shot into that envelop will hit it. At 10,000km a laser burst only takes 30 milliseconds to cross the distance.

As for stealth space is huge so hiding round planets or moons will rarely be available. Not to mention the enemy will see you coming on the way out. And there is no stealth in space. You might be able to hide yourself to visual and radar but you can't hide your heat signature. Even running cold won't help. If you fire a missile it will be hot as it leaves, the enemy could see it and their computer automatically plot it's course. If it did turn off its engine and cool down its last known position and speed will make it easy to shoot down.

Regarding jamming if you need to precisely hit their sensors then they can evade you by dodging, random course corrections and rolls. That means you have to food an area which just energetically doesn't make much sense on the scales involved in space. If you're close enough that the light takes fractions of a second to find its target you're close enough for them to just shoot you.

 

[GTOM]

But:

1. A laser will only jam a target's light and heat sensors. Sensors that work on other principles would be unaffected.
2. If the jammed target is part of a larger formation (a fleet of manned spacecraft or just one spacecraft with a surrounding network of drones) the jamming laser and its source will be visible to them.
   
3. If the jammed target is in contact with the other nearby spacecraft (or drones) as part of a tactical computer network, it's possible even the 'jammed' spacecraft could ignore the jamming by using another spacecraft 's sensors.
4. A laser would have more limited range than a swarm of missiles and (unlike a missile) firing a laser requires getting close enough to expose your own spacecraft to risk.
5. A missile can evade, unlike a laser.
6. A missile can go around asteroids and dwarf planets, unlike a laser.
7. A missile swarm can shut down their engines and act as an orbiting minefield.
8. Missiles have a continuous mode, too—we call it launch all the missiles.
   
9. Near-future technologies might very well allow a small missile to be practically invisible (active camouflage) and transparent to radar/EM/laser detection (plasma stealth). Those are both areas of active research.
10. If jamming lasers are so much better, is there any reason a missile can't carry a short-range laser of its own, along with other ECM?

1. Other types of sensors, like radar? We have radar stealth.
2-3 yes to give enough energy to all observers in the area, sure don't make it easier. :(
4. Well, i have no problem with the expose your own spacecraft thing, but it is more fun to read about missiles burst, closing in etc.
5. ?? Why should a beam evade? (FTL senses is outside the limit of human science for my setting)
6. Yes an important part in asteroid mine capturing (well, the limit between a really smart missile and a drone fighter is blurred)
7. That minefield part vs cargo ships sound interesting.
8. They should definitally try to overwhelm defences in squadrons or swarms.
9. I will read more about it.
10. No such reason, although the entire launcher ship can have much more power output.

If you're close enough that the light takes fractions of a second to find its target you're close enough for them to just shoot you.

I calculated earlier that 10m focusing mirror, 1000km distance, UV-B laser, MJ output still not enough for instant kill if i apply the (more or less futuristic) heat resistant broadband mirror armor.

 

[Artribution]

A missile cannot evade a laser point defence at close range. It can randomly change course and junk but the closer it gets the smaller the envelop of possible locations it could be in, thus more chance that a laser shot into that envelop will hit it. At 10,000km a laser burst only takes 30 milliseconds to cross the distance.

If the laser beam is meters in radius and the missile is traveling at hundreds of relative meters/second, it could be very hard to hit. And a hit might not be enough—it might need some sustained contact to burn through. And if it's not just one missile but a salvo of missiles, you might be in trouble.

Also, once the first salvo detonates (even if still quite far from the target), the light/heat/EM/particle interference generated will make salvo 2 that much harder to hit.

As for stealth space is huge so hiding round planets or moons will rarely be available.

It seems that this story takes place in the asteroid belt. What I meant by "go around asteroids" was that if you're orbiting Ceres and you want to destroy something orbiting on the far side, you can't fire a laser because it won't have enough range and it can't go around the planetoid, but a missile can. And, depending on the orbit, the engine burn required to line up an orbital intercept can be done while the target is still on the far side and unable to detect your heat signature. You can just coast from there. (At least this works in Kerbal.)

And there is no stealth in space. You might be able to hide yourself to visual and radar but you can't hide your heat signature. Even running cold won't help. If you fire a missile it will be hot as it leaves, the enemy could see it and their computer automatically plot it's course.

If they have line of sight, yes, but they might not. Or they might be very far away, potentially orbiting another planetoid. Missile range is quite far.

edit:

Why should a beam evade? (FTL senses is outside the limit of human science for my setting)

I mean the laser weapon itself can't evade very well, because it has a giant beam of light coming out of it.

 

[GTOM]

I think that burst behind celestial part could work in orbital combat. To build up enough speed to intercept fusion ship on route, a huge way is required to boost.
If the missile is coming directly for ship, that makes hit not so hard, but to focus on a small area, that requires exact distance too.
The laser beam can't detected directly in space if your sensors arent hit by it, although the lascannon will still produce quite a heat sign.
However, from 100.000km with parameters i calculated, it takes quite a time to drill through armor.

 

[Ryan_m_b]

A beamed weapon doesn't have to instantly kill, it just has to be shone on the target enough to heat damage the reflective armour and destroy it once this is done. Space is big and it takes a long time to physically move through it, even at 10Gs constant thrust it takes 41 minute to cross a light second. Within that range you can pretty easily aim a laser and be sure of it hitting. Even if it takes a solid ten minutes of shining a laser (with corrections as the missile moves and attempts to dodge) you're safe. Plus sustaining high acceleration for a long time is going to take a lot of fuel and a powerful engine. At that point your missiles become small nuclear spaceships.

It's worth noting as well that there are other forms of beam weapon that couldn't be so easily reflected, for example: particle beams, FELs and X-Ray lasers. In regards to the idea of swarming missiles sure: if you can deploy in such numerical strength then you'll win. But working with the assumptions I mentioned in the previous paragraph an attacker would need to launch 5 missiles at the defender to be sure of a win, and that's if they have only one point defence laser. If they have 10 you need to launch 41.

Edit: It would probably be useful to try and design a missile using technology appropriate for your setting. Work out the ISP and mass flow so you can figure out how much fuel its going to need to accelerate constantly and how much energy that will take. I may have a go later if I have more time than I do this evening, off the top of my head though I'd put money on any "missile" capable of doing this as becoming very large. At that point why not mount a beam weapon to it and make it a drone?

 

[GTOM]

A beamed weapon doesn't have to instantly kill, it just has to be shone on the target enough to heat damage the reflective armour and destroy it once this is done. Space is big and it takes a long time to physically move through it, even at 10Gs constant thrust it takes 41 minute to cross a light second. Within that range you can pretty easily aim a laser and be sure of it hitting. Even if it takes a solid ten minutes of shining a laser (with corrections as the missile moves and attempts to dodge) you're safe. Plus sustaining high acceleration for a long time is going to take a lot of fuel and a powerful engine. At that point your missiles become small nuclear spaceships.

It's worth noting as well that there are other forms of beam weapon that couldn't be so easily reflected, particle beams for instance. In regards to the idea of swarming missiles sure: if you can deploy in such numerical strength then you'll win. But working with the assumptions I mentioned in the previous paragraph an attacker would need to launch 5 missiles at the defender to be sure of a win, and that's if they have only one point defence laser. If they have 10 you need to launch 41.

As far as i know, particle beams scatter more than lasers (at this point i plan to introduce plasma point range defence as a breakthrough in the later half of story, but will be countered by magnetic field warheads that scatter the beam)
With the 30km/s closing speed i assumed, it is near three hours... More than a ton of titan with my previous calculations...

Hmm, although attack warship can have a ton of armor, it only have to mask the heat and light signs of attack missiles/drones by provide enough background clutter.

 

[Ryan_m_b]

Particle beams can be neutral, magnets won't affect them and they won't be repulsive so scatter won't be much of an issue (certainly not in vacuum). The U.S. Navy has a project for FEL point defence on their ships IRL. So if you're willing to speculate that there's no show stoppers were not aware of it would seem they are plausible as a long range space weapon.

As for hiding the ships I'm not convinced. You'd have to put out a fantastic amount of energy in order to "over expose" all their sensors. Bear in mind we have technology that allows cameras to filter out the light of the sun, unless you have more than that focused on the enemy ship they're going to see you.

30kmps is very slow. It would be within the effective range of a beam weapon for quite a lot of time.

 

[GTOM]

Particle beams can be neutral, magnets won't affect them and they won't be repulsive so scatter won't be much of an issue (certainly not in vacuum). The U.S. Navy has a project for FEL point defence on their ships IRL. So if you're willing to speculate that there's no show stoppers were not aware of it would seem they are plausible as a long range space weapon.

As for hiding the ships I'm not convinced. You'd have to put out a fantastic amount of energy in order to "over expose" all their sensors. Bear in mind we have technology that allows cameras to filter out the light of the sun, unless you have more than that focused on the enemy ship they're going to see you.

30kmps is very slow. It would be within the effective range of a beam weapon for quite a lot of time.

Neutral particle beams? I thought they need to be charged in order to accelerate them, two opposite charged beams can be used, but it will be still a plasma weapon. Is there some new development?

I thought at first 100 km/s but i would need at least a GW reactor, then explain why lasers could only produce a MJ / sec?

That fantastic amount of energy wouldn't be still much less than do serious damage to armor? Well, that sun filter camera is surely interesting, any link about it, how much decibel of light intensity it can handle?

Well i found that Sun is magnitude -27 6.31×10^10 compared to magnitude 0.
With 10.000km and some kW-s of light and thermal radiation, that scatter everywhere (10^14 distance squared), and few kWs laser hits all the ship it would be 10^14 more laser power than signal power.

 

[Ryan_m_b]

Read the link I posted above about modern research in particle beams. I don't understand the technology exactly but it seems like it's possible now to create a beam emitter that charges the atoms, accelerates them, then adds/subtracts an electron just as they leave creating a very fast stream of neutral particles.

As for a sun filter if you google it I'm sure you'll find plenty of examples. Its a pretty common piece of kit for photographers wanting to take pictures of solar eclipses and the like. God knows what the best possible filter could do in the world, or what could be developed by a military if needed.

Jamming sensors suffered from the same problem as beam weapons: the further away you are the more powerful a laser you need to guarantee a hit (by spreading the beam over a wider area). That quickly becomes impractical. If you're close enough that you can flood their sensors and keep doing so as they dodge and roll you're close enough to hit them with something more powerful, and be hit by the same.

 

[GTOM]

Read the link I posted above about modern research in particle beams. I don't understand the technology exactly but it seems like it's possible now to create a beam emitter that charges the atoms, accelerates them, then adds/subtracts an electron just as they leave creating a very fast stream of neutral particles.

As for a sun filter if you google it I'm sure you'll find plenty of examples. Its a pretty common piece of kit for photographers wanting to take pictures of solar eclipses and the like. God knows what the best possible filter could do in the world, or what could be developed by a military if needed.

Jamming sensors suffered from the same problem as beam weapons: the further away you are the more powerful a laser you need to guarantee a hit (by spreading the beam over a wider area). That quickly becomes impractical. If you're close enough that you can flood their sensors and keep doing so as they dodge and roll you're close enough to hit them with something more powerful, and be hit by the same.

ok, i see you edited last post, i read it.
Otherwise the good thing about particle beams, that the fusion ships rocket is also kind of particle accelerator, so technology might be bit similar...
Still, without big focusing mirrors i can hardly imagine them to be focused as much as lasers. According to link, that applies to present day xaser as well.

http://www.mreclipse.com/SEphoto/SEphoto.html
These filters typically attenuate the Sun’s visible and infrared energy by a factor of 100,000.

 

[Ryan_m_b]

I'd be inclined to think that isn't an insurmountable problem. Particle accelerators crash streams of particles together at a whisker under the speed of light and the military seems to think that hitting an object miles away shouldn't be much of a problem. If you're setting has nuclear fusion propulsion spacecraft it doesn't seem unlikely that a technique for focusing particle beams over a light second would be in use.

 

[Artribution]

It's worth noting as well that there are other forms of beam weapon that couldn't be so easily reflected, for example: particle beams, FELs and X-Ray lasers. In regards to the idea of swarming missiles sure: if you can deploy in such numerical strength then you'll win. But working with the assumptions I mentioned in the previous paragraph an attacker would need to launch 5 missiles at the defender to be sure of a win, and that's if they have only one point defence laser. If they have 10 you need to launch 41.

Considering we already have MIRV missiles that separate into 14 independently targeted re-entry vehicles each, is that really an obstacle? Just launch 10 of those and you've got a 140-missile Itano circus.

A beamed weapon doesn't have to instantly kill, it just has to be shone on the target enough to heat damage the reflective armour and destroy it once this is done. Space is big and it takes a long time to physically move through it, even at 10Gs constant thrust it takes 41 minute to cross a light second. Within that range you can pretty easily aim a laser and be sure of it hitting. Even if it takes a solid ten minutes of shining a laser (with corrections as the missile moves and attempts to dodge) you're safe. Plus sustaining high acceleration for a long time is going to take a lot of fuel and a powerful engine. At that point your missiles become small nuclear spaceships.

How do you know you can even detect them? They could (reasonably enough with near-future tech) be practically invisible to radar and visible light and if their orbit is aligned to intersect with yours, they don't even need to burn their engines.

 

[Ryan_m_b]

Again it depends on your missile. If you can carry enough to overwhelm an enemy then fine, but if you're of equal resources then you don't have that option. In terms of being detected anything hotter than the background of space can be detected with IR sensors, the hotter the easier. With an interferometer array you could be continually scanning your system and identity all objects of this sort. After its launched it doesn't matter if it goes cold and relies on radar/invisible stealth because it would be child's play for a computer to extrapolate current position based in previous speed and heading.

Even pointing your exhaust away doesn't help. The heat from the reaction (especially if you require a powerplant for the engine) will be enough to make your ship hundreds of degrees hotter than the background.