What can counter Laser weapons?

[Seret]

Seret,

My thoughts on your first reply are this: There is no hiding in space. Any space power is going to be watching everyone everywhere, they will always know where your going and generally what you are. Even doing a burn behind a planet won't help a warship once it comes back out behind the planet, due to vector changes. The best you can possibly do is disguise yourself as something your not, like a commercial vessel packed full of missiles or something.

I disagree. I think in space everything is pretty much hidden by default. Space is just so ridiculously big that small things at long ranges disappear in it very easily. Deploying enough sensors to actually provide good eyes would be a major objective for any space power, but I think expecting to have good observation of anything more than the lower layers of orbit around planets and moons is overly optimistic. There are a lot of places to hide in the bits in between.

They could easily jam your radio transmissions

You're right that EW would be hugely important in space combat, but it wouldn't be any more trivial to jam command signals in space than it is in the air or at sea. If it was trivial to jam these things would we be seeing so many UAVs entering the fray today? Would armies be fielding battlefield datanets? Would fighters have datalinks that allowed them to see targets acquired by a remote AEW and even let that AEW fire their missiles for them? Secure RF comms and data is something the military can do.

Spacecraft are low power, warships probably won't be.

What fundamental difference do you imagine there would be between a armed and an unarmed satellite? The armed one would probably spend most of its time dormant. If it wasn't actually engaging the enemy it wouldn't necessarily need to be doing anything except waiting for orders. I would expect a combat spacecraft to consume far less power than a commercial one for much of the time.

Lasers and railguns are very thirsty electricity wise

Any weapons are likely to store their energy in chemical form, if only because the interval between launch and use is likely to be years. So kinetic weapons with solid rocket motors, or guns seem simple and reliable candidates. Maybe chemical lasers. I think any weapon that required a large power plant to operate would rule itself out on weight, stealth and longevity grounds.

[khyron42]

Regarding lasers again:

A friend was involved in optics research a few years ago and had a fun PhD project. It was developing a tunable pulsed laser.

First, get a group of sub-microsecond pulsed lasers that fall at the various absorbtion/emission wavelengths of a particular gaseous medium. Get them set up to all pulse in (relative) sync and along the same axis. I think he was using an IR laser, a few visible-light ones, and a UV one or 2. The point was, they blanketed 7 excitation & emission states of the target medium, with about equal power (low power in the lab but it would work at higher energies.)

Feed them into the gaseous medium, let's call it the "dial-a-laser". It's going to basically let them through in slightly altered state since it absorbed and re-emitted them, some at different wavelengths than they came in at due to cascaded emissions or excitations.

He built an adaptive feedback genetic algorithm and gave it control to alter the incoming synchronization. Tell it which output frequency you wanted and it would quickly tweak the phase relationships to get as much of the output as possible there. While there were losses in the system, it was pretty impressive to see 7 various wavelength lasers going in... and over 50% of that energy come out as UV with small remaining amounts of the others coming out. And then switch the software and a few dozen pulses later - less than tenth a second - have 60% of green laser coming out. (the losses were lower at the middle emissions options, because it could optimize better for possible emission scenarios there.) This only worked on the wavelengths that gas was capable of emitting, and took advantage of quantum effects from the interaction of femtosecond synchronized pulses with the gas' electron's excitation states.

Of course for anything weapons-grade this would have a whole slew of new challenges and you could get better results from using 4 separate high-powered lasers at different frequencies. I just found it very interesting that, if light emission is electrons dancing among their various energy states, they'd found a way to call the tune, so to speak. Much of his other doctoral work was on a team that got pulses short enough and in-phase with each other enough to take advantage of those electron state interactions.

[Rickenbacker]

Sand...

If your combat is taking place at high closing velocity, the sand becomes a weapon as well.

Not sure which scifi book i read it in but using lasers to ablate kinetic kill weapons, altering their trajectory was used. May have been plasma weapons of some sort.

The sand thing is from the old Traveller rules. In the newer editions, they removed the sandcasters, since throwing enough sand between you and a laser weapon to stop much of the energy would be incredibly impractical. You'd basically be carrying around millions of tons of sand to possibly stop one shot, then you'd be defenseless anyway..

[Pds314]

Anything that obscures the line-of-site requirement.

Or reflects the laser.

There are two kinds of laser weapons:

Heater-weapons: use a laser to melt a hole in the target or outright overheat it over several seconds/milliseconds.

Pulse weapons: heat up tiny areas of the target to ludicrously high temperatures by taking microseconds or less to emit several hundred joules.

The first type is simple to counter, spin whatever it is rapidly and give it a highly thermally conductive material as armor with a not-so-conductive material underneath.

E.G.:

Something reflective (or if your feeling really mean, retro-reflective) on top

Diamond or liquid helium or copper or all of the above inside.

Carbon nanotubes to protect the user/equipment below that.

When facing a pulsed laser, thermal conductivity of your armor it not very important, what is important is that your armor is thick and again reflective (or retro-reflective) enough to reduce damage.

Upon impact, the laser will essentially all hit the same exact point, this is because it will take such a tiny fraction of a second to start and finish hitting, that the sound, heat, and path of newly translucent matter will not form in time to do anything interesting

Even if it got heated to say, several hundred times its own boiling point, the laser would finish hitting it before it would become transparent, and thus leave a crater-shaped or spherical divot depending on the presence and effect of air, NOT a circular hole in whatever it hit.

One possibility for dealing with a laser like this is to wear a thick suit that is thermally insulating on the inside, but readily releases heat, e.g. foam over carbon Nanotubes.

The reason is simple, a laser vaporizes an amount of matter more-or-less proportional to its energy, so wearing 10-inch thick foam armor will basically make you invulnerable to any individual hit, same thing with being inside a cloud of thick smoke or sand.

An interesting result of this is that the really overpowered weapon is not a laser, it is a transonic or supersonic submarine, using acceptible amounts of G-force, such a vessel could be invincible to nearly anything, it has miles of murky water to defend it from lasers and radar, if it is programmed to turn randomly and often, it can't be aimed at with any other type of weapon, and it will outrun or at least mostly escape nukes detonates sufficiently far away as to prevent the flash being visible through water.

Did I mention it has an unlimited supply of fusion fuel?

Basically, hitting one would be like going deep-sea fishing with a harpoon and the exact positions of where the fish were 5 minutes ago, you'd be shooting blind.

But back to spaceships, I design the following: A spaceship with a bubble of dark-particulates, an atmosphere of sorts, around it, the outside is full of robots with retro-reflectors covering their surface, which means any object firing a laser at it will hit ITSELF too.

This is also similar to what we live on, Gamma rays aren't a problem on Earth because we have an atmosphere.

Also, I could always design a grain of sand that is composed of three perpendicular planes, then throw a hundred billion of them at your ship, if you fire, they reflect your lasers back within a millimeter of where they were launched from and block any stray beams. this has the added benefit of causing your laser-guns to be disabled, while in all likelihood keeping the rest of your ship intact for negotiations or using missiles against (now that your missile-defense has conveniently self-destructed).

[meve12]

The problem with that being mirrors REFLECT radiation, not absorb or redirect it. Even if you carefully shape the mirrors to redirect it somehow, you'll still have made yourself more visible in at least one direction.

Concerning shielding particles, there are two problems:

The first is density. This being vacuum, maintaining a dense enough cloud would be difficult. Maybe use magnetic particles so they attract eachother?

The other, bigger problem is laser ablation and it's usefulness as a thruster. The particles may absorb some energy, but a weapon's grade laser would start vaporizing the exposed sides, essentially acting as a tiny thruster.

So a spacecraft cowering behind it's cloud-wall would receive a weakened laser, depending on the absorbing and radiating ability of the particles...and then a good portion of the rest of the laser's energy, in the form of "micrometeorites" being driven along by the laser.

That being said, spreading out such a cloud would make good chaff. It wouldn't be stealthy, but you can keep the gunners guessing...

[meve12]

Apologies, I was responding to this:

"Just cover your ship in mirrors. +1 for easier hiding from enemies without sensors, too. Not to mention if you're about to board the ship and want to make sure you want to look good, the window will serve you well. "

[FellipeC]

Lightsabers, of course.

[Galacticruler]

Actually it depends on the laser, the mirror and anthing in-between the laser emitter and the target.

A laser powered by a million blue-ray scanners will perform terribly compared to a 200Mw argon based laser.

Edited September 27, 2013 by Galacticruler

[AlexisBV]

Anyone feel nostalgic and ready to reinstall Freespace, and X-Wing? Not really space combat as the maneuvering is atmospheric, but still... The space bombs in X-Wing were ballistic IIRC. Not that there was any gravity to alter their course, though.

[Rakaydos]

How about Fighter-missiles?

Launch them from a linear accelerator, (railgun) they use low temperature RCS for guidance/evasion, and when they get close they use a turreted, modular weapon system system. Shaped charge nuke, Explosively formed projectile or chemical laser for high closing velocity, where you would only get one shot. Directional sensor jamming, Maser EMP and conventional missiles if the FMs are able to match velocities well enough for a significant engagement time.

[Rakaydos]

Anyone feel nostalgic and ready to reinstall Freespace, and X-Wing? Not really space combat as the maneuvering is atmospheric, but still... The space bombs in X-Wing were ballistic IIRC. Not that there was any gravity to alter their course, though.

I always had more fond feelings for Homeworld and Independance War. Give me things larger than a snubfighter.

[Simon Ross]

Errr smoke

Kinda why most T72 tanks didn't last very long in the first gulf war

[KASASpace]

Electromagnetic fields.

Why?

Because if you can alter the laser's path enough, you could essentially dodge it by activating the field. Earth's field already renders lasers a pretty much useless weapon, not to mention it requires gases that are expelling colloquially. So, not only do you need a bunch of power, but a bunch of gas.

As an anti-missile system I would go with some sort of mini casaba howitzer. It uses a nuclear reaction to heat a material into a plasma and ejects it in a certain direction. THis is good for vaporizing targets at medium range.

[Kryten]

Electromagnetic fields.

Why?

Because if you can alter the laser's path enough, you could essentially dodge it by activating the field. Earth's field already renders lasers a pretty much useless weapon, not to mention it requires gases that are expelling colloquially. So, not only do you need a bunch of power, but a bunch of gas.

You managed to not say a single thing applicable to lasers in that sentence. You're talking about sci-fi 'plasma guns'.

As an anti-missile system I would go with some sort of mini casaba howitzer. It uses a nuclear reaction to heat a material into a plasma and ejects it in a certain direction. THis is good for vaporizing targets at medium range.

You've messed up nuclear reactors and bombs again, but this time the other way; casaba-howitzer is a full-sized shaped nuclear warhead, an outgrowth of the work on Orion. It'd only be usable once against a single target, and wouldn't be effective outside of the atmosphere.

[KASASpace]

You managed to not say a single thing applicable to lasers in that sentence. You're talking about sci-fi 'plasma guns'.

You've messed up nuclear reactors and bombs again, but this time the other way; casaba-howitzer is a full-sized shaped nuclear warhead, an outgrowth of the work on Orion. It'd only be usable once against a single target, and wouldn't be effective outside of the atmosphere.

Really?

Okay.

Lasers generate heat, you need a coolant of some kind (hence "gas") and/or radiator (a lot of them)

I messed it up? Either way a nuclear "bomb" goes through a nuclear reaction just as a nuclear "reactor."

It is a shaped charge, and is an outgrowth of Orion.

And by "mini" I meant that it doesn't need to have the full effect as to vaporize a small missile, you could use less than 100 pounds of Plutonium. Or, maybe, more efficient nuclear reactions can be made (by the time we expand to space and start fighting in it, we should have this tech) and thus get smaller, like 25 pounds, and considering Plutonium is very dense, this would be an effective "mini casaba howitzer."

And Orion's nuclear pulse drive used very small warheads, that can shoot a lot of tungsten onto the (hopefully ablative) plate.

Edited February 7, 2014 by KASASpace

[Kryten]

Really?

Okay.

Lasers generate heat, you need a coolant of some kind (hence "gas") and/or radiator (a lot of them)

Nice try, but you explicitely said a laser could be deflected by an EM field. Your statement was either;

A) about plasma weapons, and therefore nonsense in this context

or

about lasers, and completely wrong, and therefore nonsense in any context.

I messed it up? Either way a nuclear "bomb" goes through a nuclear just as a nuclear "reactor."

Oh wow, 'goes through a nuclear'. Nice terminology. Still haven't worked out nuclear criticality and supercriticality are completely different things?

Or, maybe, more efficient nuclear reactions can be made (by the time we expand to space and start fighting in it, we should have this tech) and thus get smaller, like 25 pounds, and considering Plutonium is very dense, this would be an effective "mini casaba howitzer."

I should hope we'd be able to make 25lb of plutonium into a bomb in this far future of yours, given even fat man only took about 15. Still wouldn't result in one nuclear bomb vs. each 'small missile' being remotely worth it.

[KASASpace]

Nice try, but you explicitely said a laser could be deflected by an EM field. Your statement was either;

A) about plasma weapons, and therefore nonsense in this context

or

about lasers, and completely wrong, and therefore nonsense in any context.

Oh wow, 'goes through a nuclear'. Nice terminology. Still haven't worked out nuclear criticality and supercriticality are completely different things?

I should hope we'd be able to make 25lb of plutonium into a bomb in this far future of yours, given even fat man only took about 15. Still wouldn't result in one nuclear bomb vs. each 'small missile' being remotely worth it.

Do you even know what a laser is? It's an electromagnetic wave, and thus is affected by fields of the same type, and I never said deflect, it changes the trajectory of said laser.

And have you checked for edits on my post?

The Little Boy was over 100 lbs of Uranium, and less than 1% of the Uranium even REACTED. Get your facts straight.

[Kryten]

Do you even know what a laser is? It's an electromagnetic wave, and thus is affected by fields of the same type, and I never said deflect, it changes the trajectory of said laser.

Electromagnetic fields act on charges, EM radiation is made up of uncharged photons. This is like the nuclear stuff; just because two things have the same word in the name, it doesn't mean they act in the exact same way.

The Little Boy was over 100 lbs of Uranium, and less than 1% of the Uranium even REACTED. Get your facts straight.

A simple slip of the tongue. You'll find those figures are accurate for Fat Man, which is what I meant.

[KASASpace]

Electromagnetic fields act on charges, EM radiation is made up of uncharged photons. This is like the nuclear stuff; just because two things have the same word in the name, it doesn't mean they act in the exact same way.

A simple slip of the tongue. You'll find those figures are accurate for Fat Man, which is what I meant.

Electromagnetic fields act on much more than charges. The electromagnetic waves move through the field, and thus are "refracted"

Either way, less than anything useful as a Casaba-Howitzer. And, btw, please just stop being so rude about this. It's not necessary.

And it's much more than "per missile barrage, you launch equal number of Casaba-Howitzers"

I was thinking more like, one small thing intercepts on the case of less than 10 missiles, and when there's a HUGE number of missiles (as should be the case) you break out the Casaba-Howitzer.

BTW

Any ACCURATE sources?

[Kryten]

Electromagnetic fields act on much more than charges. The electromagnetic waves move through the field, and thus are "refracted"

Give a single example of this actually happening. You said the earth's own field was powerful enough to deflect lasers; in that case something like an NMR machine should effectively be impossible to even see properly.

Either way, less than anything useful as a Casaba-Howitzer.

That doesn't even make sense.

And it's much more than "per missile barrage, you launch equal number of Casaba-Howitzers"

I was thinking more like, one small thing intercepts on the case of less than 10 missiles, and when there's a HUGE number of missiles (as should be the case) you break out the Casaba-Howitzer.

But Casaba-Howitzer can still only ever hit one target. All you'd need is a large enough stockpile of small kinetic-kill missiles, and it's goodbye to your massively expensive defense system.

[KASASpace]

Give a single example of this actually happening. You said the earth's own field was powerful enough to deflect lasers; in that case something like an NMR machine should effectively be impossible to even see properly.

That doesn't even make sense.

But Casaba-Howitzer can still only ever hit one target. All you'd need is a large enough stockpile of small kinetic-kill missiles, and it's goodbye to your massively expensive defense system.

I mean in high-power lasers, not just everyday lasers. Like Lasers powerful enough to actually DO things.

Define "sense"

It projects a blanket of plasma, that can vaporize nearly entire barrage of missiles.

[Rakaydos]

Or, maybe, more efficient nuclear reactions can be made (by the time we expand to space and start fighting in it, we should have this tech) and thus get smaller, like 25 pounds, and considering Plutonium is very dense, this would be an effective "mini casaba howitzer."

I'm sorry, but "Small" and "Efficent" are opposites when it comes to nuclear material. The more material you have, the more efficently it uses that material. You can stack on more explosives, making a subcritical mass dence enough to start going supercritical, but the reaction will blow itself apart before 90% of the nuclear material is consumed.

[Rakaydos]

It projects a blanket of plasma, that can vaporize nearly entire barrage of missiles.

I think you need to read the orion document again. Casabla Howetzer was NARROWING the beam of the orion shells, to try and get more range out of them.

[KASASpace]

I'm sorry, but "Small" and "Efficent" are opposites when it comes to nuclear material. The more material you have, the more efficently it uses that material. You can stack on more explosives, making a subcritical mass dence enough to start going supercritical, but the reaction will blow itself apart before 90% of the nuclear material is consumed.

Um, then why did Little Boy use over 140 pounds of nuclear material and have 1% efficiency? Compared to what Kryten claims (15 pounds in Fat Man, 10 times the efficiency).

[Kryten]

I mean in high-power lasers, not just everyday lasers. Like Lasers powerful enough to actually DO things.

the c#vast majority of Lasers are at the same sort of wavelengths as visible light; the power just comes from having more photons. If a field doesn't deflect photons, it doesn't deflect photons, it wouldn't make any difference how many there are.

It projects a blanket of plasma, that can vaporize nearly entire barrage of missiles.

No, it was intended to project a fine jet of plasma, hence the capacity to destroy things. A 'blanket' of plasma would disperse to uselessness incredibly quickly.