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Comment by ufmace | Hacker News Reader

It'll be an interesting development if somebody manages to put a real laser weapon like this in the field and it ends up being effective against vehicles and aircraft. Missiles are expensive and relatively slow; a laser weapon could potentially shoot down missiles and aircraft so fast as to be a game-changer.

There's been a lot of noise about whether aircraft carriers and other capital ships are viable at all in the face of high-speed anti-ship missiles. Intercepting them with CIWS and counter-missiles is dicey, but a good laser system could make anti-ship missiles useless.

On the other hand, you have to wonder if operating aircraft at all might become non-viable if your enemy has weapons like that. Speed might become much less important and stealth much more important.

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Speed just becomes more important which is why counties are developing hypersonic boost glide weapons such as https://en.m.wikipedia.org/wiki/WU-14

Hypersonic doesn't get you anything close to the speed of light. As long as the targeting electronics can handle the hypersonic speed of the target - and those electronics are not getting slower - hypersonic won't make much difference.

Presumably the amount of energy dumped into the target is a function of how long the laser dot is on it. You'd probably need the laser on a particular area of the target a little while to disable it.

If your target is ducking behind waves and goes from beyond the horizon to onto of you fast enough, that would be pretty good against a laser probably?

Also in a real shooting war there won't just be a one or two missiles launched against an aircraft carrier, but 10s at least or maybe over a hundred. Tom Clancy's book Red Storm Rising examined this scenario.

It might just be a battle of the algorithms then... is your radar + laser interceptor better than their missiles' agility and countermeasures?

It's also a question of volume: if you can shoot down 15 missiles, then can I get 20 in flight?

There are also things like rail guns, which might be harder to intercept with a laser.

Yeah... that's a lot of momentum to deal with, in a rail gun. Deflecting it would be hard, and disrupting it would tend to turn the slug into a co-moving cloud of superheated particles/plasma. I'm not sure that's hugely desirable either!

Well, that superheated cloud would probably disperse some, making it more susceptible to air resistance than the slug is. On the other hand, if you only liquefy it, and so you get hit with the same mass of liquid metal...

Oh god. It might be a better outcome for the actual vessel, but...

You know, I think you'd just see a radical re-design in that case, you'd have to; like the Zumwalt, only more armored.

If you can launch 20, I can add another laser. Just in terms of economics, you aren't going to win that fight.

A rail gun: If I shoot a laser at a missile, I can detonate the warhead, or the propellant, or destroy the guidance system. If I fire it at a railgun projectile, I can vaporize the whole thing, or I can vaporize part of it and hope that it changes the course due to either ablation forces or changing the aerodynamics. That's harder. On the other hand, a railgun isn't really a precision weapon, either.

> Intercepting them with CIWS and counter-missiles is dicey, but a good laser system could make anti-ship missiles useless.

Of course, such a good laser system could make the aircraft, missiles, and landing craft launched from aircraft carriers, assault ships, and major surface combatants useless, too, at which point the survivability of the ships themsleves is something of a moot point.

I don't think that current laser systems are anywhere near powerful enough to destroy a landing craft. I think that reason why lasers are potentially effective against aircraft and missiles is that they are intrinsically fragile and rely on speed to avoid getting hit. But a landing craft can afford to have some armor, and I don't think it takes much armor to stop a laser.

Yeah, on a landing craft, expect some form of ablative armor. (How friggin' Star Trek is that?!)

Isn't it almost always easier to mirror the outer surface of a missile than to deliver enough additional photons to burn through a mirrored surface?

The advantage of laser weapons isn't that they're the best response to expensive, high-end threats (say, a big supersonic missile) - the advantage is that they're cheap and suitable for low-end threats, since you pay pennies per "shot".

A few days ago there was an article about a US ally shooting down a ~$200 drone with a ~$3M Patriot missile, which is a great trade for the attacker in that scenario (like a pawn for a rook). Even assuming that there's some kind of coating that makes a missile laser resistant by dramatically reducing absorptivity in the spectra of concern, it's bound to have tradeoffs- likely in the form of expense, weight, or increased vulnerability to sensors.

A pawn for a rook? That's like a pawn for 1000 queens.

In the short term, while the technology is still pretty new, perhaps. But that would assume an agility on the part of the people building the targeted missiles that I'm pretty sure only players like Russia and China can offer, and we don't want to get into a shooting war with them, anyway. For most of the other states (or non-state actors) that we might be exchanging fire with, that's out of their reach, making this a potentially very cheap (relatively) and effective countermeasure.

Moreover, if battlefield lasers follow the growth-curve of most other technologies, they will quickly reach a point where, not only is adding power to the lasers easier than adding armor to the missiles, the amount of additional mass required becomes infeasible.

On the flip side, it seems that mirroring the surface of a missile or UAV would make it easier to detect, and therefore easier to target with "legacy" systems. I imagine both legacy and laser-based systems would be used in conjunction with each other.

Lasers are also cheap to operate compared to missiles. And for things lasers can't shoot, there's always that railgun the Navy made.

Enough military budget will eventually make SF real. Can't wait for the battle mechas.

Yeah there's nothing quite like horrendous human suffering to satisfy your hunger for sci-fi. /s

Look at the bright side -- we seem to be approaching a point where the expected outcome of any serious war is one of either (1) no human lives lost at all, because high-tech weapons blow each other up before they can actually hit anything living or (2) a few of those high-tech weapons make it through the defenses, efficiently destroying your civilization in a matter of a few minutes and constraining human suffering to that brief period. :)

Mechas will always remain SF. There's just so much that's impractical about them, where do you even begin. Balance is one issue: if you can make it fall over, you've killed it. Speed is another; anything that big will be extremely slow. Another issue is the ground pressure (weight divided by surface area of feet); they would destroy most surfaces (including all roads), and they would easily get stuck this way. Another issue is the huge amounts of fuel and frequent refueligs it would need. Another is the huge cost, which coupled with sluggishness and corresponding permanent proximity to the battlefront makes them a prime target for infiltration and sabotage.

Even something as comparatively small and practical as the Boston Dynamics robots have failed to gain traction; years after even being in actual service for testing with the military, LS3 has been literally shelved because it's just not useful.

One of the funniest battle mecha scenes is from Pacific Rim (which is chock-full of stupidity) where the one mecha is just a crappy missile delivery system. Once it's waded half way out to sea and spent its missiles in about two seconds, it's bloody useless. Why didn't they rather spend the cash on other, more sensible launch platforms that could deliver orders of magnitude more firepower using the same kind of missiles? Or why not just attack the alien things much further away from shore with torpedoes launched from fighter jets? Or why not just launch nuclear-tipped torpedoes down the portal hole? (Well, it would be a boring movie, that's why.)

> you have to wonder if operating aircraft at all might become non-viable

Yay F-35!

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