The BIG SECRET of directed energy weaponry is that there's a very simple and cheap method of reducing absorbed energy by orders of magnitude - reflect it in arbitrarty directions (or even towards the source if one wants to be naughty).
The sensors (which have to absorb EM radiation to function) are vulnerable, but can be easily protected by shutters for the duration of attack. Modern inertial navigation units are well capable of providing precise guidance without any external data.
This already exists somewhat (e.g. antiflash white paint on aircraft expecting to operate in a nuclear conflict area) but given that today's environment seems to favour stealth (you can't lase something you haven't detected yet, and considering how fast these missiles move the trade-off in survivability vs. detection time and thus time for the target to acquire, track, and shoot down the hypersonic missile is probably not worth it) I doubt mirrored missiles will come into fashion.
But, I am very much an "airchair" weapons technologist so I'd be interested in seeing arguments for the contrary!
> When it comes to ballistic missile defense, “you want to get it into airborne platforms and into space,” said Evan Hunt, a former U.S. Air Force navigator who now works in business development for Raytheon’s high-energy laser products. “It’s better to look down than to shoot up.”
What about atmospheric interference? (And whatever unfortunate soul might be behind the missile assuming the laser misses.)
This was a main focus of a huge amount of research backing Regan's "SDI" - Strategic Defense Initiative, back in the 80s. [1]
The field of wavefront adaptive optics[2] was a major civilian-side outcome of that work, with eventual impacts on human vision correction (e.g. LASIK, esp. for people w/ major astigmatism) and ground-based astronomy.
> with eventual impacts on human vision correction (e.g. LASIK, esp. for people w/ major astigmatism)
That's really neat! I'm a beneficiary of this - with both nearsightedness and major astigmatism, I was told by the ophthalmologist that did my intake for LASIK that there was a non-trivial chance that the surgeon would decline to perform my operation (luckily he was in a confident mood). I went from completely non-functional without glasses to seeing 20/20 in one eye and 20/15 in the other.
While the benefits are diffuse, it's easily one of the top most impactful experiences in my life. It's akin to the feeling of successfully refactoring away a mountain of legacy tech debt that had been getting the job done but bogging you down. Getting rid of the tech debt feels great, but removing the cognitive load of even having to factor it into any decisions anymore just makes things more pleasant.
It's interesting to learn that, indirectly, I owe that to Regan's defense spending.
You can’t hit an ICBM early in its flight because you won’t have seen it yet/haven’t figured out yet whether it is heading for you. You don’t want to hit it late in its flight because it will be above your territory, and you don’t want to run the risk of dropping radioactive waste there.
What? If somebody launches a nuclear ICBM, I don't care where it's heading, I want it downed ASAP, preferably right next to where it launched.
An ICBM also likely isn't going to be above my territory when the propellant drops. After that the tiny missile heads are going to be very hard to hit. That's why you need these laser systems in space (the "Star Wars" program) so you can hit them right after launch.
Lastly, the risk of "dropping radioactive waste" is far lower than the risk of having a nuclear warhead detonate at its target destination.
”If somebody launches a nuclear ICBM, I don't care where it's heading, I want it downed ASAP”
Countries do missile tests. Some of them do not announce them because they want to avoid embarrassment when it doesn’t launch or goes boom.
If you attack any launch that looks like an ICBM, you will attack those, too, certainly if you want to down it “right next to where it launched”, as that gives you a very short time to decide whether the missile is armed with nuclear explosives.
I think that what you say comes down to that you’re willing to risk war to deny countries of doing any ICBM missile test.
Nobody so far has tested an actual nuclear-armed ICBM. Sure, maybe North Korea is testing ICBMs unannounced, and it's a big problem, but we "know" they aren't nuclear-armed. If the technology existed, these should be shot down, no matter the payload.
> I think that what you say comes down to that you’re willing to risk war to deny countries of doing any ICBM missile test.
"Accidentally" shooting down an unannounced ICBM out of precaution is not necessarily an act of war, nor will it necessarily lead to war.
I imagine it depends on the altitude of the object the laser is targeting. Say if there was a missile flying along the edge of the mesosphere vs a missile 1 km above ground.
> Lastly, there’s the “line-of-sight” problem; lasers shoot perfectly straight, meaning a laser shot toward the horizon will eventually hit the Earth’s curves.
Huh, and here I thought the Hollow Earth theory had been discredited, but I guess I might believe Raytheon and its lasers. Cyrus Teed would be so pleased.
I'm not sure what the earth being solid or hollow has to do with this. If you're on the surface of a ball, you can only project a laser / straight line over the hemisphere above you; not through the ground.
As an example, if you're at the North Pole and the South Pole base fires a ballistic missile at you, you can't aim a laser at it, as it would diametrically intersect the Earth.
Instead, you have to wait until the missile passes your horizon. The point at which it does this depends on its altitude. Hypersonic vehicles attempt to make interception harder by reentering the atmosphere from space earlier than a traditional ICBM, and travelling at a lower altitude in their final phase.
I think it was a joke. The way the quote was worded makes it sound like the Earth is curving upwards - if you shoot straight to the horizon you'll hit air, not the ground.
To me it sounded like a journalist's awkward wording of a description from an engineer. Some frequencies of light will bend to the curvature of the earth due to the atmosphere[1]. Lasers apparently "hit the Earth's curves" rather than bending with them.
This happens everyday with the sun during sunrise and sunset [1]. When you first see the apparent top of the sun during sunrise, the sun is still well below the horizon physically. It's just that the image of the sun is refracted around the curvature of the earth a bit.
The original quote said "a laser shot toward the horizon will eventually hit the Earth’s curves."
No, on a sphere a laser shot towards the horizon will not hit the Earth's "curves."
Shooting towards the horizon is by definition shooting tangentially to the surface you are on. The horizon is the point where the sky meets the land or sea. If you make a straight line from your laser to the horizon, it will continue out into space.
Your explanation of what they meant makes sense: a laser shot towards a distant target, not towards the horizon. But that's not what they said. And, obviously, I did not actually think the fault was the engineers' but the journalist's explanation.
Also, it's not like you're going to see the bullet hitting your head, or the landmine that'll blow you up, or the IED that you tripped over. Not until it's too late, anyway.
See how we’re hurtling toward lasers that can stop hypersonic missiles.
Sounds like Raytheon is taking the page about concept cars from the car industry and talking about totally conceptual products like they've already shipped.
I don't see why such lasers would require high power. Couldn't an array of smaller lasers be used instead? It seems to me this would also counteract blooming and add redundancy. If using microwave / radio radiation instead, a phased array would allow the system to be instantly and multiply targetable.
Most hypersonic weapons already require ablative materials to transit the atmosphere without disintegrating. Ablative shielding is the norm. Even then, a lot of engineering goes into ensuring that ablative loading is carefully controlled during flight -- any significant deviation from the designed ablative loading will cause catastrophic failure. It took decades of research to get to the point where a (non-ballistic) hypersonic missile under normal flight conditions could reliably manage the ablative loading long enough to reach its target. They are literally testing the theoretical limits of material physics.
Massively increasing the external thermal loading of those materials during flight is a great way to kill a hypersonic vehicle. It directly attacks one of their most vulnerable design constraints.
So the control algorithm for the glide vehicle is going to correct for damaged ablative/control surfaces? I don’t believe this technology currently exists.
The scenario under discussion was the use of ablative surfaces to prevent damage. I'm not sure (I doubt) this is actually an effective countermeasure though.
Compensating for damaged control surfaces isn't impossible in all cases though, for the most part, fly-by-wire systems are servomechanisms which will scale their responses until the desired feedback is produced.
For a ballistic or hypersonic missile you need it anyway, to radiate away atmospheric heating.
The challenge with an ABM laser weapon system is generating enough power on-target that it's not just a rounding error for the energy that needs to be dissipated anyway. A quick back-of-the-envelope physics calculation indicates that'll be hard. An 80kg warhead is moving at about 5000 m/s upon re-entry and has a kinetic energy of about 1 GJ. I dunno what fraction of that kinetic energy is converted into thermal energy upon re-entry; for manned spacecraft it's "almost all of it" because they need to go subsonic for parachutes to deploy, but for ballistic missiles, let's guess 1/1000th for ease of math, or 1 MJ. Current laser weapons systems have a range of about 1mi (and the range of lasers is heavily limited by atmospheric considerations - atmospheric refraction will reduce your accuracy, while heating of water vapor, dust, and air can sap the energy). That's about 1/3 of a second on target, so the power output needed is about 3 MW. Current laser weapon systems like the AN/SEQ-3 have a power output of about 30 kW. This needs to scale up by a factor of 100 under conservative assumptions.
Like the article said, the solution to many of these issues is to put the lasers in space and intercept missiles in the boost phase. Then they're moving slower, you're targeting volatile fuel & oxidizer instead of heat shields, and you don't have atmospheric losses to worry about. You do have the issue of how to loft a giant laser, capacitor, and energy source into orbit, though, and how to protect them up there when a conflict starts.
This is a good point, the weak spot is that the missile designer "knows" where the extra energy is coming from (friction with the air). Once you add a laser, the energy can come from "any" angle (within some limits of course).
Think of it this way, the shuttle could not dissipate massive energy on the 'top' because re-entry involved air over the bottom.
As for power rating, the Boeing High Energy Lasers were demonstrating effective missile defense in 2017[1], they were ramping up their power levels pretty quickly.
I see the biggest impact early on being fleet defense against hyper-sonic anti-ship missiles rather than ABM defense. Basically a CWIS replacement since it doesn't help to lose your $10B aircraft carrier to a $100M missile.
Warheads spin on re-entry anyway, so laser energy directed at any point other than the centerline (which is pretty hard to hit) will get dissipated and spread across the whole warhead.
I think the biggest impact is actually against low-tech threats: swarms of fast attack suicide boats, or 1960s-era cruise missiles that have ended up on the black market. There's a big cost advantage to being able to take these out with a quick 30kW pulse rather than a million-dollar missile, particularly since the threat itself probably cost less than a million dollars.
In a great-power conflict (where "great-power" is rapidly expanding to include private multinational corporations) the U.S. military is fucked anyway, but then, so is the opposing power. Perhaps that's the best we can hope for, because it's a pretty strong incentive not to start great-power conflicts in the first place.
> In a great-power conflict [...] the U.S. military is fucked anyway, but then, so is the opposing power. Perhaps that's the best we can hope for, because it's a pretty strong incentive not to start great-power conflicts in the first place.
Yes. That is indeed the concept of a (nuclear) deterrent.
Let's suppose the threat to such a laser weapons platform in orbit during conflict which you touch on in your last paragraph consists of 1+ missiles.
Could the targeting system of the platform not consist of some kind of movable/adjustable prism that could acquire a target not just straight down on Earth's surface but also in other directions?
Such a system (if feasible) could probably also cut down hugely on time needed for and the amount of repositioning the weapons platform has to do during operation (thinking about and writing this sentence made the image of Tony Starks basement particle accelerator appear in my head again).
Would probably need a good bit of extra fuel for course corrections too. I'd imagine that a lot of ablative material gassing off on the side close to the earth would have course impact. And influence aerodynamics.
Great, so maybe one attack vector is defended, and that of 2nd-rate States trying to lob 80 year old technology.
Missile defense has been in development for decades, and it never works. By the time it does, missiles will
look like cross-bow bolts on the warfare menu.
Isn't there going to be a pretty short list of targets that are more valuable than the missiles themselves? I can see an aircraft carrier making sense, but it feels like there are cheaper ways to blow up most other targets.
The main trouble with ground-based is clouds, that is what makes you go airborne.
I could picture planes in the air 24-7 circling around vulnerable points, or being dispatched on warning. Either way it would be expensive but would be awesome.
>I could picture planes in the air 24-7 circling around vulnerable points
The US previously spent a few billion and 16 years on that exact idea as part of the SDI, before canceling it a few years after the first working tests because, to quote the Defense Secretary,
>I don't know anybody at the Department of Defense who thinks that this program should, or would, ever be operationally deployed. The reality is that you would need a laser something like 20 to 30 times more powerful...there's nobody in uniform that I know who believes that this is a workable concept[0]
If the laser power was a problem, maybe Raytheon's tech will make the concept more plausible. The wikipedia article says there's been some additional experimentation mounting lasers on UAVs since the program was cancelled.
There is terminal defense against ICBMs and there is midcourse defense against hypersonics.
The ballistic warhead has little more to do than absorb the heat of reentry in the terminal phase. The energy to destroy it would be a good fraction of the energy that was in the rocket to begin with.
The hypersonic weapon on the other hand has to have sensors, effectors, and be unable to complete it's mission after receiving less beamed energy.
The airborne laser was killed not because it wasn't powerful enough (for some mission) but because the chemical laser it used was dangerous, expensive and otherwise impractical. The air force knew the army was developing modular fiber lasers so they decided to wait for that before building another platform, which could also be used against everything from drones to small ballistic missiles.
Hypersonic is just the cherry on top.
The alternative for interception hypersonics would be the nuclear-tipped ABMs of old, since the maneuvering capability of hypersonics defeats "hit-to-kill".
No Latin American countries have nukes, and despite spending most of the 19th century beating the stuffing out of each other on a regular basis [1] there's been almost zero inter-state violence since WW2.
Modern Russia is also nowhere near the unstoppable conventional military juggernaut that the Cold War-era USSR was.
You'd also have to consider the likelihood of one getting through your laser defences, and what the cost of protecting your country with these would be.
If you have a 99% chance of stopping a missile, but your adversary has tens or hundreds of thousands of missiles to fire at you, those aren't great odds.
Plus in a pinch, modern societies could probably come up with some fairly hideous deterrent weapons that didn't require missile delivery.
That’s a good point, and in fact probability of error doesn’t even need to come into play. If you can destroy 10 missiles per second with probability 1, then you have a 0% chance of stopping 11 missiles at once. Massive simplifications here but the point stands. Scale matters.
As in "mirrors".
The BIG SECRET of directed energy weaponry is that there's a very simple and cheap method of reducing absorbed energy by orders of magnitude - reflect it in arbitrarty directions (or even towards the source if one wants to be naughty).
The sensors (which have to absorb EM radiation to function) are vulnerable, but can be easily protected by shutters for the duration of attack. Modern inertial navigation units are well capable of providing precise guidance without any external data.