No, it doesn't work like that. The military is of course tight-lipped about exactly how powerful SHiELD is, but at least one site claims that the goal is 50kw [1]. That's a lot of power. A few years ago, a 30kw laser test made the rounds in news outlets for destroying a few targets during testing. [2]
Mirrors don't perfectly reflect light in all frequencies. Mirrors are designed to reflect mostly visible light, lasers at this power level are infrared. Any imperfections in the reflective surface would immediately heat up, damaging the reflective surface, which would then heat up even more. And even if it were perfect, and were designed to reflect whatever frequency of radiation the laser's putting out, it's still not going to reflect 100% of the laser's output, and you've probably got yourself a material that's pretty impractical for a rocket.
The way you asked the question implied that everyone working on the project must be kind of stupid. "simply" "how hard can it be" while showing a lack of expertise on the subject made you sound conceited.
The question itself was fine and got interesting answers. Phrased differently, I don't think anyone would have downvoted you.
Despite what other commentators say, mirrors would work in theory. In fact lasers themselves have mirrors.
High quality mirror material with > 99.8% reflectivity near infrared region would do the job. Multi layer metal substrate, usually copper based or fused silica to withstand thermal expansion and dielectric coating. High macroscopic surface quality is not needed. It's enough that it reflects.
Even the mirrors used in laser erode. Laser weapon uses larger mirror area to focus tighter beam to the target. But unlike laser mirror missile surface don't have to withstand erosion long time and you can rotate the missile to divide the thermal power to larger area.
There are practical reasons why the best practical option is not mirror but material with high thermal resistance. Hypersonic missiles already use those materials and they are protected against current generation of military lasers (50 to few 100s of kilowatts). You need megawatt lasers if you try shooting down HGV.
"normal" mirrors don't really work for high-power lasers. If you try to reflect a high-power laser with your bathroom mirror, in the (very short) first moment it will reflect most of the beam, the part that's not reflected will burn the mirror and suddenly it's not a mirror anymore in the spot that the laser hits.
You’re doing that ‘I am very smart and have found an obvious flaw sitting here that none of the professional missile engineers thought of’ thing. Makes a lot of people cringe.
Mirrors would work for a low power laser, but not for what they were testing. There are other options though. The simplest one is a spiky elongated nose cone, which would dramatically reduce delivered power density for a missile on head-on trajectory. Add an ablative cone and you can defeat laser power levels realistically available in the near future, compact enough to be placed in a pod under a wing. Bear in mind that chemically powered laser will have limited number of shots available. Electrically charged one (with super-capacitor) will need significant delays between shots. In both cases they can be overwhelmed by a large enough number of missiles.
Besides the other problems noted, mirrors and ablative shielding aren't really practical for guided missiles which target aircraft or ships. The missile needs an infrared/optical/radar seeker. So it would be difficult or impossible to find a material which would be electromagnetically transparent for the missile's own seeker but also protect it against incoming laser wavelengths.
Good question - being in a somewhat cloudy part of the world I wonder what effect weather would have on this kind of system. Can you only defend yourself on clear days?
Even if the missile is not destroyed, optical sensor systems must necessarily absorb some light, and will probably be destroyed. This is a possible tactic employed by less powerful lasers, too.
Missile defense systems have always had a very basic and fundamentally insurmountable weakness that people just willfully ignore. It costs almost nothing to make more decoys, and it costs an astronomical amount to upgrade your system to track and handle more targets. Building any missile defense system is a nearly guaranteed way to destroy yourself. The enemy just builds more decoys for almost nothing, and then you go broke.
All the acronyms are over the top. Have they heard of my Project SCIMITAR? (Symbolically Capturing Information by Making Inane Trite Acronyms to Rememberstuff)
Joking aside, if they can get this into a compact form that can be adequately supplied and cooled, it'll be a quantum leap in weaponry. You're talking about going from hurling chunks of matter that in turn impart kinetic and thermal energy, to being able to project energy directly.
Question: say one of these planes is flying above me and someone shoots a surface to air in the general direction of this plane, and in the process of destroying said missile an errant laser beam strikes me as I watch from the ground. What happens to me? Mainly curious as to the power of the beam as a thought experiment.
Lets assume the laser works by dumping a lot of thermal energy into the missile. It's safe to assume for two reasons - primarily because I think that the power requirements for anything other than that would be ridiculous, and because they specifically talked about 'destroying' the missiles in question, rather than simply burning out the sensor package. Also...that's pretty much how laser/directed energy weapons work - you dump energy into a point until it catches fire.
People are mostly water (citation needed). Missiles are mostly meta (ibid)l. Water takes a lot of energy to heat up, while metal heats up quite easily - we know this because we know that a Calorie {kilo-calorie for those at home} is the amount of energy needed to raise 1 kilogram of water 1 degree C, and is equal to ~4500 joules. To do the same thing to copper and steel, you need something like 350 and 500 joules, respectively (this is a property called specific heat, and is really cool and I wish I wasn't bad at thermo so I could talk about it more accurately).
Anyway, it takes a very large amount of energy to hurt a person, and a smaller amount to destroy a missile. There are two ways of getting that energy out of a laser - in one big ass pulse, or in a longer stream. Looking at the mount, and the platform the laser is to be deployed on, I believe this works with a 'stream' of energy. Fighter jets are not power plants (citation needed) and have a lot of high powered electrical equipment on them already (radar(s), communications devices, whatever sensor packages they have, flight avionics, cooling, and the computer(s) that co-ordinate all this). You don't want your displays going dark because you're charging the laser. Additionally, high energy pulses tend to be destructive to their components. Having only one anti missile shot before you have to under go maintenance to replaced a bunch of fused emitters and whatnot doesn't' seem like the best idea. With a lower energy continuous beam, you don't have that destructive flow, and while the total power draw is probably similar to a pulse, you're pulling that over a longer period, which is much easier to plan for.
Pulling it all together - the laser's target has different thermal properties than a human does, and probably takes a few seconds 'on target' to work. Depending on how long you stayed in the beam, I'd expect anything from first to second degree burns, probably from the water in your cells turning to steam and bursting, but nothing catastrophically bad unless you were lasered continuously the entire time, and even then I don't think it would kill you, just burn you quite badly.
Unless you looked into it. That would probably go poorly for everyone.
I imagine Israel would be at the top of the list of interested parties for this technology -- it sounds much cheaper than the Iron Dome since I assume there isn't a real per-shot charge other than the energy required.
It would also be much faster than their current interceptors.
I just wonder how well it would work against low-tech targets.
It also would be well-suited to shorter-range attackers - Iron Dome can only intercept missiles with a minimum range of about 2.5km.
Israel is pursuing its own high-energy laser defense program, Iron Beam (yes, not so creative). From public sources, it's not clear if the thing is 1-2 years from deployment, or if it's in development hell; the US is uniquely public about these high-budget prestige projects for internal political reasons.
> That's not to say that SHiELD, at least as described presently, doesn't have limitations. A turreted laser can only ever engage one target at a time and there is the aforementioned risk of atmospheric disruptions reducing the beam's range and efficacy
So to intercept 20 missiles you'll need 20 expensive "turrets", your enemy knows how many "turrets" you have and can easily flood it with more cheap missiles.
Also remember that target destruction is not instantaneous, this limits the amount of targets per "turret" and the minimum range.
Laser weapons might have their uses, just hope that the it isn't a cloudy day, or say, the enemy uses something like a mirror for that specific frequency, or even better, something that emits a dust cloud that eats the energy. Missiles, of course, can fly through dust clouds.
Scattering by droplets/aerosols is an effect that drastically reduces the capability of an optical system to focus at range, it's like shining a flashlight through milk - not the same as variations in air density that you could maybe partially compensate for using adaptive optics.
In rain, common LIDAR wavelengths, like 905nm and 1550nm lose about 0.1-1% of their power due to scattering per meter travelled and on top of that 0.1-1% due to absorption. Of course, this will not scale linearly with higher power but it's a lot even if it's ten times less.
For laser weapons to be effective you need a clear line of sight in the respective wavelength.
Power efficiency makes lasers in fighters problematic. The current cutting edge lasers have 35 percent efficiency. If you heat the target with 100 kW power, the fighter absorbs 300 kW of heat. You can use fuel to absorb the heat but heat exchangers adds lots of weight and extra complications.
How wide is the beam ? How long does it need to stay focus on roughly the same point ? Wouldn't spinning your missile prevent a beam to being focused always on the same point ? Does adding random jitter to your missile trajectory prevent focusing ?
I wonder if there's any chance this could spur development of effective anti-ICBM laser systems. Considering that nuclear ICBMs are the only real existential threat to the United States, I'm often surprised they don't spend a huge chunk of their defense budget neutralizing that threat.
I worry if a single nation would be first to develop effective ICBM countermeasures, the whole MAD doctrine would collapse on the spot and we'd have a next world war on our hands.
Take this all with some massive grains of salt. The language is very vague. When it comes to "shooting down" a missile much depends on definitions and locations.
An inbound air-to-air missile is a very tricky target. It is face-on. Your laser cannot target the explosive bits of the missile (the rocket motor that is active for the first few seconds of flight). But that doesn't matter. "Shooting down" can mean jamming the missile's IR sensor or damaging its radar dome, both of which would stop it as a threat. The real problem imho is the size of the emitting aperture. Focusing a laser tightly at any distance requires a device probably too large for a fighter aircraft.
Shooting down a missile from the side, from the ground or form an escort aircraft is another matter. Get it during the boost phase (the first few seconds after launch) and even a pinprick through the side of the rocket motor will cause it to explode. But in that scenario why wait for the missile to be launched? If you can burn through the rocket motor after launch, you can do so before launch. My point: any weapon capable of explosively shooting down misses in flight is also capable of shooting down the launching aircraft before it gets a chance to fire.
Oh, and don't forget that such weapons are probably illegal under various treaties. If it can shoot down a missile a one mile it can blind a pilot at ten. Pointed at the ground it could blind scores of troops. Some legal hoops would need to be jumped before one could ever deploy such a laser.
> The real problem imho is the size of the emitting aperture. Focusing a laser tightly at any distance requires a device probably too large for a fighter aircraft.
Focusing a laser onto a 100mm point at 5km does not seem like it would take that large of an aperture, and that should be all you need to kill the seeker.
> Get it during the boost phase (the first few seconds after launch) and even a pinprick through the side of the rocket motor will cause it to explode in a true "shoot down".
IIRC most air to air missiles have a boost phase far longer than that - I think most will still be burning at intercept for shots inside the killbox. That's part of the selling point of the Meteor [0] - it can throttle, so it'll almost always be burning at intercept.
> But in that scenario why wait for the missile to be launched? If you can burn through the rocket motor after launch, you can do so before launch.
It's a lot easier to argue that the other side shot first when you blow up the missile AFTER it leaves their plane. Not to mention the case where the responsible aircraft wasn't detected until after launch...
Now that off-boresight missiles are coming into service I wonder how long it'll be before fighters can use missiles to shoot down missiles like you see in modern naval engagements.
Also, I know the F-35 has the power plant to run one of these but could one be mounted on an F-22?
[+] [-] gingabriska|6 years ago|reply
It's just a light bean albeit concentrated one, how hard can it be to deflect it?
Edit: don't understand the downvoting, please enlighten. Your wisdom is not obvious to me. Thanks
[+] [-] thaumaturgy|6 years ago|reply
Mirrors don't perfectly reflect light in all frequencies. Mirrors are designed to reflect mostly visible light, lasers at this power level are infrared. Any imperfections in the reflective surface would immediately heat up, damaging the reflective surface, which would then heat up even more. And even if it were perfect, and were designed to reflect whatever frequency of radiation the laser's putting out, it's still not going to reflect 100% of the laser's output, and you've probably got yourself a material that's pretty impractical for a rocket.
[1]: https://phys.org/news/2018-03-air-fighter-mounted-laser-summ...
[2]: https://newatlas.com/lockheed-martin-laser-truck/36377/
[+] [-] dboat|6 years ago|reply
The question itself was fine and got interesting answers. Phrased differently, I don't think anyone would have downvoted you.
[+] [-] naval-gazer|6 years ago|reply
High quality mirror material with > 99.8% reflectivity near infrared region would do the job. Multi layer metal substrate, usually copper based or fused silica to withstand thermal expansion and dielectric coating. High macroscopic surface quality is not needed. It's enough that it reflects.
Even the mirrors used in laser erode. Laser weapon uses larger mirror area to focus tighter beam to the target. But unlike laser mirror missile surface don't have to withstand erosion long time and you can rotate the missile to divide the thermal power to larger area.
There are practical reasons why the best practical option is not mirror but material with high thermal resistance. Hypersonic missiles already use those materials and they are protected against current generation of military lasers (50 to few 100s of kilowatts). You need megawatt lasers if you try shooting down HGV.
[+] [-] tsbinz|6 years ago|reply
[+] [-] hurtle_shurtle|6 years ago|reply
You’re doing that ‘I am very smart and have found an obvious flaw sitting here that none of the professional missile engineers thought of’ thing. Makes a lot of people cringe.
[+] [-] pauljurczak|6 years ago|reply
[+] [-] baq|6 years ago|reply
[+] [-] onion2k|6 years ago|reply
[+] [-] nradov|6 years ago|reply
[+] [-] fsh|6 years ago|reply
[+] [-] arethuza|6 years ago|reply
[+] [-] pletnes|6 years ago|reply
[+] [-] Paraesthetic|6 years ago|reply
[+] [-] inflatableDodo|6 years ago|reply
[+] [-] unknown|6 years ago|reply
[deleted]
[+] [-] otakucode|6 years ago|reply
[+] [-] rdiddly|6 years ago|reply
Joking aside, if they can get this into a compact form that can be adequately supplied and cooled, it'll be a quantum leap in weaponry. You're talking about going from hurling chunks of matter that in turn impart kinetic and thermal energy, to being able to project energy directly.
[+] [-] S_A_P|6 years ago|reply
[+] [-] mr_overalls|6 years ago|reply
https://www.youtube.com/watch?v=rthHSISkM7A&t=16s
[+] [-] hguant|6 years ago|reply
Lets assume the laser works by dumping a lot of thermal energy into the missile. It's safe to assume for two reasons - primarily because I think that the power requirements for anything other than that would be ridiculous, and because they specifically talked about 'destroying' the missiles in question, rather than simply burning out the sensor package. Also...that's pretty much how laser/directed energy weapons work - you dump energy into a point until it catches fire.
People are mostly water (citation needed). Missiles are mostly meta (ibid)l. Water takes a lot of energy to heat up, while metal heats up quite easily - we know this because we know that a Calorie {kilo-calorie for those at home} is the amount of energy needed to raise 1 kilogram of water 1 degree C, and is equal to ~4500 joules. To do the same thing to copper and steel, you need something like 350 and 500 joules, respectively (this is a property called specific heat, and is really cool and I wish I wasn't bad at thermo so I could talk about it more accurately).
Anyway, it takes a very large amount of energy to hurt a person, and a smaller amount to destroy a missile. There are two ways of getting that energy out of a laser - in one big ass pulse, or in a longer stream. Looking at the mount, and the platform the laser is to be deployed on, I believe this works with a 'stream' of energy. Fighter jets are not power plants (citation needed) and have a lot of high powered electrical equipment on them already (radar(s), communications devices, whatever sensor packages they have, flight avionics, cooling, and the computer(s) that co-ordinate all this). You don't want your displays going dark because you're charging the laser. Additionally, high energy pulses tend to be destructive to their components. Having only one anti missile shot before you have to under go maintenance to replaced a bunch of fused emitters and whatnot doesn't' seem like the best idea. With a lower energy continuous beam, you don't have that destructive flow, and while the total power draw is probably similar to a pulse, you're pulling that over a longer period, which is much easier to plan for.
Pulling it all together - the laser's target has different thermal properties than a human does, and probably takes a few seconds 'on target' to work. Depending on how long you stayed in the beam, I'd expect anything from first to second degree burns, probably from the water in your cells turning to steam and bursting, but nothing catastrophically bad unless you were lasered continuously the entire time, and even then I don't think it would kill you, just burn you quite badly.
Unless you looked into it. That would probably go poorly for everyone.
[+] [-] iguy|6 years ago|reply
[+] [-] hurtle_shurtle|6 years ago|reply
[deleted]
[+] [-] sdrothrock|6 years ago|reply
It would also be much faster than their current interceptors.
I just wonder how well it would work against low-tech targets.
[+] [-] azernik|6 years ago|reply
Israel is pursuing its own high-energy laser defense program, Iron Beam (yes, not so creative). From public sources, it's not clear if the thing is 1-2 years from deployment, or if it's in development hell; the US is uniquely public about these high-budget prestige projects for internal political reasons.
[+] [-] mariefred|6 years ago|reply
So to intercept 20 missiles you'll need 20 expensive "turrets", your enemy knows how many "turrets" you have and can easily flood it with more cheap missiles.
Also remember that target destruction is not instantaneous, this limits the amount of targets per "turret" and the minimum range.
[+] [-] noobermin|6 years ago|reply
[+] [-] wnkrshm|6 years ago|reply
In rain, common LIDAR wavelengths, like 905nm and 1550nm lose about 0.1-1% of their power due to scattering per meter travelled and on top of that 0.1-1% due to absorption. Of course, this will not scale linearly with higher power but it's a lot even if it's ten times less.
For laser weapons to be effective you need a clear line of sight in the respective wavelength.
[+] [-] mnw21cam|6 years ago|reply
[+] [-] asdff|6 years ago|reply
[+] [-] naval-gazer|6 years ago|reply
[+] [-] Symmetry|6 years ago|reply
[+] [-] GistNoesis|6 years ago|reply
[+] [-] asdff|6 years ago|reply
[+] [-] tomphoolery|6 years ago|reply
I feel like Val Kilmer is about to make an epic bowl of popcorn with this thing.
[+] [-] jeffrogers|6 years ago|reply
[+] [-] danmaz74|6 years ago|reply
Is this true for a laser mounted on an airplane? How is the energy stored?
[+] [-] Causality1|6 years ago|reply
[+] [-] TeMPOraL|6 years ago|reply
[+] [-] sandworm101|6 years ago|reply
An inbound air-to-air missile is a very tricky target. It is face-on. Your laser cannot target the explosive bits of the missile (the rocket motor that is active for the first few seconds of flight). But that doesn't matter. "Shooting down" can mean jamming the missile's IR sensor or damaging its radar dome, both of which would stop it as a threat. The real problem imho is the size of the emitting aperture. Focusing a laser tightly at any distance requires a device probably too large for a fighter aircraft.
Shooting down a missile from the side, from the ground or form an escort aircraft is another matter. Get it during the boost phase (the first few seconds after launch) and even a pinprick through the side of the rocket motor will cause it to explode. But in that scenario why wait for the missile to be launched? If you can burn through the rocket motor after launch, you can do so before launch. My point: any weapon capable of explosively shooting down misses in flight is also capable of shooting down the launching aircraft before it gets a chance to fire.
Oh, and don't forget that such weapons are probably illegal under various treaties. If it can shoot down a missile a one mile it can blind a pilot at ten. Pointed at the ground it could blind scores of troops. Some legal hoops would need to be jumped before one could ever deploy such a laser.
[+] [-] DuskStar|6 years ago|reply
Focusing a laser onto a 100mm point at 5km does not seem like it would take that large of an aperture, and that should be all you need to kill the seeker.
> Get it during the boost phase (the first few seconds after launch) and even a pinprick through the side of the rocket motor will cause it to explode in a true "shoot down".
IIRC most air to air missiles have a boost phase far longer than that - I think most will still be burning at intercept for shots inside the killbox. That's part of the selling point of the Meteor [0] - it can throttle, so it'll almost always be burning at intercept.
> But in that scenario why wait for the missile to be launched? If you can burn through the rocket motor after launch, you can do so before launch.
It's a lot easier to argue that the other side shot first when you blow up the missile AFTER it leaves their plane. Not to mention the case where the responsible aircraft wasn't detected until after launch...
0: https://en.wikipedia.org/wiki/Meteor_(missile)
[+] [-] dba7dba|6 years ago|reply
[+] [-] baybal2|6 years ago|reply
[+] [-] Symmetry|6 years ago|reply
Also, I know the F-35 has the power plant to run one of these but could one be mounted on an F-22?
[+] [-] amelius|6 years ago|reply
https://www.physicsforums.com/threads/does-a-laser-have-a-re...
[+] [-] gnode|6 years ago|reply
[+] [-] gandutraveler|6 years ago|reply
[+] [-] Haga|6 years ago|reply
[+] [-] Circuits|6 years ago|reply
[+] [-] b_tterc_p|6 years ago|reply