Slashdot Mirror
Laser Weapon Shoots Down Airplanes In Test
airshowfan writes "Boeing's directed-energy weapons (a.k.a. frickin' laser beams) have been getting some attention lately. The Advanced Tactical Laser (ATL) is a C-130 that famously burned a hole through a car's hood, and the YAL-1 AirBorne Laser is a 747 that shoots a laser from its nose that is powerful enough to bring down an ICBM. But even cooler is the Mobile Active Targeting Resource for Integrated eXperiments (MATRIX), a laser that is mounted on a truck (which probably costs less than a 747, but who knows) and that can shoot down small aircraft, as shown in the picture on this article. (The Laser Avenger supposedly also has this capability). We live in the future!"
Ignoring the fact that you can't make an object shiny enough, because there'll always be a thin layer of dust, crud, or even oxides on the surface...
So when do our soldiers get to stop dying because of homemade street bombs?
Yeah, but if you make your plane shiny and reflective, you make it a lot easier to target with other weapons, like missiles.
We all know what to do, but we don't know how to get re-elected once we have done it
Develop me a functioning Magnetic shield mechanism, so that I can mount both on a 1-man-space-capable-fighter, and get me a date with Natalie Portman, and my fantasy is complete.
So when do our soldiers get to stop dying because of homemade street bombs?
When we stop invading other countries?
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Let me know when my government learns to do anything effectively besides killing
Apparently they capture the heat generated by the server as it gets slashdotted to recharge the laser. Keep clicking the links lads, it's your patriotic duty.
Once I was a four stone apology. Now I am two separate gorillas.
Yes, IIRC they said it would take billions of dollars and 30 years to make and wouldn't be effective against ICBMs.
I read the internet for the articles.
Unless you have a gigantic Jiffypop skillet in the foyer! Then it's popcorn for everybody! (At least until the Mythbusters go and ruin my fun.)
Wouldn't making your plane or missile shiny / reflective defeat these things pretty easily?
The answer is no, because no shiny surface has 100% reflectivity (your bathroom mirror probably tops out at around 85%): some of the light will always penetrate to the base layer, and if the surface is being hit by a megawatt weaponized laser, it'll just burn straight through.
Dislike the Electoral College? Lobby your state to join the National Popular Vote Interstate Compact.
A laser that powerful would convey enough impulse to make a hole without needing to heat the target.
What mechanism would cause that type of effect?
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
Could this Laser help with refining metals on the Moon? Could I use this machine to smooth a road, or carve a tunnel? Outside of making the Bad Guys day miserable, what OTHER uses could this tool have?
It's quite easy. Make sure that you have a defense contractor in every congressional district. Then you get to play the "jobs" card when someone tries to stop an idiotic waste of resources such as this.
Dwight Eisenhower must be turning in his grave now that the Military Industrial Complex that he warned of has come to pass.
Drill baby drill - on Mars
The goal for the 747-mounted laser is to shoot down missiles on the way up (when they are over bad guys) versus on the way down (like the Patriot missile). That's why it's on a plane, not a truck.
Well, the fact that they are over the people who just launched the missle is a side benefit, and doesn't really factor into why they are shooting it at that stage.
In the primary phase, the missile is pretty limited in what it can do. It has to gain altitude and speed, and really isn't/can't be built to perform evasion at that point. Combined with the fact that the earlier you hit it, the more combustible it actually is.
On the way down, what you are faced with is a VERY fast moving object (assuming you don't target the countermeasures) that has already demonstrated that it can resist the high temperatures of re-entry and consists of very little in the way of combustible materials. It can also employ a variety of measures to alter its trajectory (more than on the way up).
Out of modpoints but really liked a post? 1BDkF6TtmmeZ3yqXbz9yhdYVqRYnwFoXDj
well, that's easy... just attach 30 bathroom mirrors IN SERIES. that would reduce it it 1% of the original.
-- I was raised on the command line, bitch
Czarangelus...
I always wondered where you would pop up after you were banned on Fark. (A pretty impressive feat in its own right). Needless to say, you certainly haven't stopped with the flamebait.
Out of modpoints but really liked a post? 1BDkF6TtmmeZ3yqXbz9yhdYVqRYnwFoXDj
EA has had this in Command and Conquer Zero Hour for quite a few years now. I'm guessing the U.S. military ripped this off from EA.
boycott slashdot February 10th - 17th check out: altSlashdot.org
Plus, the 747 can carry a larger tank for the sharks
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
Once everybody dies, there will be no more evil. Problem solved.
The heat which boils away the paint surely also destroys the reflective properties of the material beyond.
The Tao of math: The numbers you can count are not the real numbers.
instead of a police action where every activity is on film or subject to investigation.
I doubt we could have won WW2 under the rules we use now, people no longer have the stomach to do what needs to be done.
I know that your point is true, but we also lose soldiers to bombs elsewhere. We also manage to lose many times more to drunk driving yet we turn a blind eye to that.
* Winners compare their achievements to their goals, losers compare theirs to that of others.
That won't work. The problem starts at step 2. If the top layer isn't reflective, then as it "boils away" it will convert incoming energy from the laser into heat efficiently enough to destroy any reflective layer that might be under it.
Even if that weren't the case, you'd still have a problem at step 3, because your reflective surface will still absorb too much energy. An expensive mirror that's new, clean, and in perfect condition would still absorb 5% of the energy hitting it in lab conditions. In the air, in combat conditions, coated with goo from the stealth paint that just got burned off of it, the reflective layer wouldn't last even a measurable fraction of a second.
Optical vs. radio is just a choice of wavelengths. Whatever wavelength you pick to be shiny, can be used to detect you. Whatever wavelength you choose to be "not shiny", can be used to destroy you.
I wish GP hadn't bothered to mention the problem of stealth, because it's diverting attention from the point that matters - no material of any sort can be kept sufficiently reflective under combat conditions that the laser wouldn't destroy it. So really, even whatever wavelength you pick to be shiny, can still be used to destroy you.
Each photon in the beam transfers its momentum to the target. For total reflection it transfers twice its momentum. This will result in radiation pressure exerting a very localized force (so high pressure), and if there is any absorbtion it will heat up the material locally, causing a temperature shock, since the immediate surroundings don't get time to heat up.
So, a Beowulf cluster of bathroom mirrors, then?
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
Wow, really? These are all just corporate welfare programs? I guess all the knights in the Middle Ages said that firearms were just affirmative action programs so that poor, untrained, conscripted villagers could compete on a level ground against knights. You can never predict the ways in which methods of combat shift, and so you have to continue to fund initiatives such as these. The current method of conflict now is clearly unconventional and asymmetric, however it could easily switch back to traditional, set-piece combat(ie. WWII and theorized Cold War confrontations). If this shift occurs, Strykers, MRAPs, COIN planes will do nothing for us. That's why we need to continue developing air-to-air technology, ground-to-air technology, and the likes. These things won't win us the current wars, but they damn sure might win us the next ones.
The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
Ronald Regan, he played the role of George "The Gipper" Gipp in the film "Knute Rockne, All American;" from it, he acquired the lifelong nickname "the Gipper."
RUGBYRUGBYRUGBY
Will will stop invading when they promise to stop trying things like hijacking planes and flying them into really tall buildings to kill a few thousand civilians.
What country were those hijackers from, again?
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
$1M missile vs firing a laser. I do not know how much it costs to fire a chemical laser but I bet it is a lot cheaper than firing a missile.
"You can actually accomplish that with plated layers of reflective material and dialectric material. However, all I then have to do is count on the explosion of the topmost dialectric layer to destroy the reflective layers beneath it.
Fixed.
Moderators: Parent may not understand the answer to his/her question, but that doesn't make parent a troll. WTF?
Parent: The mirror won't reflect 90% for very long. Not long enough for it to matter where the reflected energy goes, I expect. Perhaps collateral damage to other mirrors in the area; or, more seriously, I suppose it could damage the vision of anyone who was looking at the target from the wrong angle.
Which future is it?
I suggest you read George Orwell's 1984, to find the answer to that question.
If I were God, wouldn't I protect my churches from acts of me?
The laser *ITSELF* has two mirrors.
Why doesn't it burn?
"Aim Away From Face"
A unique way to learn a language: http://languageloom.com
So you want to make a radar resitant stealth supersonic high heat coating that burns away cleanly.
Yes I said that right. Supersonic speeds produce friction which make heat. So by design you have a stealth coating that ablates when ever you travel fast.
Something tells me you haven't seen all the angles yet.
i thought once I was found, but it was only a dream.
No, I wouldn't happen to work for Boeing. I would happen to have taken basic physics, though.
For the sake of argument, I'm going to pretend that your idea of shedding a stealth layer would work, because it's moot. You can call my statements "mighty assumptions" all you want, but I'll stand by them. If I'm wrong, we'll surely see the headline that proves it soon enough.
As for this: "A laser weapon designed to fry a plane that absorbs 70% or more of it should be less than effective if the said plane absorbs only 5%."
Wrong. The 5% is only the initial amount of energy that gets through. That's enough to destroy the mirror so fast that you'll never notice any of the laser reflecting away. From that point forward, the target receives close to 100% of the laser's energy and is destroyed quite effectively.
And, that 5% is a very optimistic figure. Again, that's for a clean, flawless, perfectly maintained mirror made for lab use and kept under lab conditions.
I know it's much easier to bitch about lack of citations then to do, say, a google or wikipedia search on reflectiveness of mirrors, but I'm just gonna leave that as your problem.
Power != energy. Energy is not measured in watts. Come back once you understand that.
Coding with assembly is like playing with Legos. Coding an application in assembly is like building a car with Legos.
Homework assignment! To rip apart sheet metal, you'll need a pressure in the ballpark of 100 PSI.
Calculate the laser power needed to create this much radiation pressure with a 10-cm diameter beam.
Answer:
100 PSI = 69 N/cm^2
A = pi r^2 = 78 cm^2
F = P * A = 5400 N
F = dp/dt = 2 I/c
I = F c / 2 = 5400 * 3e8 / 2 = 800 GW
This amounts to 1/4 of total U.S. electricity consumption. Utterly impractical.
With the world economy in the toilet, all-time record in unemployment, massive desertification, energy shortage, more than 1 billion starving, epidemics of malaria, AIDS and tuberculosis, global warming, what we really really need is the ultimate super cool weapon.
Not that I believe your premise, but what better time to have a superweapon than when other countries start getting desperate enough to attack?
You can shoot down UAVs with this thing? WOOOOOW. Current UAVs are the short fat pimply kids of military aviation: they're slow and stupid, and you can shoot them down with conventional missiles, antiaircraft artillery, or a well-aimed fart.
This is why we only use them in asymmetric warfare situations, where the bad guys are armed with nothing but Ak-47s. They wouldn't last 30 seconds in the airspace of any competent superpower.
Designing a zillion dollar laser system to shoot them down is a pointless waste of money.
This is a bit like gunpowder weapons in the 14th century. They appeared in Europe early in that century, were pretty pointless at first, then useful in special cases, then, after about 100 years, more-generally useful. Professional soldiers at that time must have been pretty skeptical. "Interesting, but I'll keep the trebuchet for now, thanks." Up to, say, 1350, it would have been difficult to predict whether gunpowder would ever become a practical weapon.
On the way down, what you are faced with is a VERY fast moving object (assuming you don't target the countermeasures) that has already demonstrated that it can resist the high temperatures of re-entry and consists of very little in the way of combustible materials. It can also employ a variety of measures to alter its trajectory (more than on the way up).
A few minor points:
1. It can resist predictable high temperatures, for a limited amount of time, if I heat up part of the RV that isn't designed to get quite as hot, I can cause the whole thing to tumble and fail.
2. It doesn't have to explode, I just have to make it slightly less aerodynamic, and let friction do the rest.
3. So called "Maneuvering RVs" don't change trajectory all that much. Mostly they make very fine adjustments so they hit their target, not to avoid things coming at them.
I assure you - the Cleveland Browns would still suck if they played by NBA rules. They could fuck up a game of Calvinball.
Weaselmancer
rediculous.
Hence why it's newsworthy that someone has created this weapon. Contrary to the title, using it to destroy test targets isn't. The purpose of this weapon, specifically, is to prevent greater destruction by lesser destruction (building and life VS missile). Also, destruction and creation are two sides of the same coin; improvement of the world requires both creating good and destroying the existing bad.
A mirror on an ICBM needs to last maybe one blast, so it does need replacement nor cooling.
95% reflectivity seems to achievable relatively easily. A megawatt * 5% = less than it has to endure when going down, I'd assume.
Each photon in the beam transfers its momentum to the target. For total reflection it transfers twice its momentum. This will result in radiation pressure exerting a very localized force (so high pressure)
Hm... I can't find anything specific about the power, just "mega-watt class". So let's call it a megawatt and we can multiply the result as necessary. I'm also going to guess it's a 1.315um COIL laser. Momentum per photon is h/lambda = 5.039e-28 kg*m/s, energy is hf = 1.511e-19 J. The megawatt laser therefore produces 6.618e24 photons/s, so assuming total reflection that's a force of about 0.0066 N.
I don't know how tightly the beam is focused, but if it's 1mm^2 (which seems pretty damn tight, someone else can calculate the divergence), that's a pressure of about 6600 Pa, or about 6% of standard atmospheric pressure. How many atmospheres do you need to damage a plane?
I dunno, I have a hard time believing radiation pressure is going to be a significant factor in the effectiveness of a laser.
The enemies of Democracy are
A couple comments here are focusing on stealth, that's not the big question.
There is not a single US Gen 2+ stealth aircraft engaged in Iraq/Afghanistan. F-117s have been retired, B-2 are not needed. The aircraft over there are relying on a variety of other IR countermeasures (tactics/flares/directed IR) to defeat threats.
TFA is talking about shooting down UAVs, which pose a unique problem because they are very small and can be made out of low-tech composite stealth materials like frickin balsa wood. That, combined with a naturally low IR signature because of their low performance envelope, make it hard to target then with traditional guided weapons (IR and Radar guided).
The key question, which TFA avoided giving details about, is what range they are talking about. If the range is = a 25mm chain gun, this system has little value yet, as if you can find it and track it, a turreted chain gun is already very deadly, the ballistics models aren't that hard to compute. But those weapons are also very easy to fly above.
If this laser has a range of, say, 8 miles (40,000-ish feet), then things could get interesting. Data that would also be important is how long the laser needs to stay on target, and how small the beam is. If the beam is 1" wide, and must stay on the same spot for 1/2 a second, it could be defeated by old-fashioned 'jinking' which would move the beam around and diffuse the heat. But if it's 1/100 second, then again, it's really deadly.
Finally (and then I'm done), this laser is really cool, but must be guided by something... at 40,000 feet (or at night), you'll need something better than a Mk 1 eyeball to find and track the target accurately enough, just like you do today, and that's where countermeasures could be applied.
But a really good EO/IR guidance system that can find/track targets up to 40,000 feet on a clear day at night and a laser that can kill in 1/100" second (or close), and you've got a game-changing technology, forcing aircraft to hope for cloudy days.
It goes like this: No concievable missile shield could shoot down any significant number of incoming missiles. The Russians would always be able to overwhelm the defenses with shear numbers, making the system worthless.
Totally true, if you only have a few lasers. And that's all we have now at the moment. It's worth mentioning though that originally back in the 50's we only had a few transistors and they were the size of dixie cups.
Now I'm not saying that laser equipment will scale like that, but I am saying that it will scale to some degree. Maybe there is a Mitch Taylor-esque lab coat out there somewhere who is going to figure out something better. In fact I'm sure there is.
We're just now getting to the point where lasers are becoming battlefield possibilities. These are essentially laser flint lock rifles. But - enough R&D and eventually we'll move up to six shooters, gatling guns, full auto machine guns, Phalanx anti missile gun points... All it takes is successive small improvements, and you can't get those without the original flint lock gun. As they say, the rest is details.
Put a few hundred planes in the air that have increased effectiveness laser systems with millisecond reload and a few hundred shot capability and suddenly you might have that workable shield.
As it is today, maybe the scenario plays out the way you suggest. But that's only if the tech stands still and never improves. And it's a sure bet that it won't.
Weaselmancer
rediculous.
...unless it's raining. Or cloudy. Or foggy. Or dusty. Or smoggy. Or snowing.
Cress, cress, lovely lovely cress
Maybe. Chemical lasers are hard to pulse, unless you Q-switch them. (but then you waste some energy when the Q-switch is off.
A favorite technique these days is to use multiple diode lasers to pump a glass slab. It's the same thing in principle to green laser pointers which have a single laser diode pumping a ND:YAG crystal. (The green light comes from a frequency doubling crystal) In a weapon laser, you'd have hundreds of multi-watt infrared diodes pumping multiple doped glass slabs all bathed in a liquid whose index of refraction matched the glass at the wavelength(s) you are creating. The liquid also cools the system and the output mirrors. The diodes can be pulsed or continuous.
B.t.w if you have enough gain in your system, you don't need and output coupler mirror, just the highly reflective mirror behind your laser medium.
All ideas^H^H^H^H^Hprocesses in this post are Patent Pending. (as well as the process of patenting all postings)
no material of any sort can be kept sufficiently reflective under combat conditions that the laser wouldn't destroy it.
Indeed. A more fruitful approach would probably be more similar to reactive armour; a material that produces large amounts of refractive or absorbing smoke particles to dissipate the beam and rapidly transport the energy away; a cursory reading about directed energy weapons indicate that even the ordinary vaporization of the target can cause shading problems.
Various kinds of vapour countermeasures might also have the advantage of providing beam tracing possibilities for a retaliatory strike.
So what about the "invisibility cloaks" (http://tech.slashdot.org/article.pl?sid=09/05/13/2215220) that are being researched. At some point could those metamaterials theoretically redirect the energy from these lasers?
...if you dump enough energy into the air near an infinitely-shiny object to explosively transform the nearby air into a plasma, the shiny object still probably gets a big dent in it. Probably even more so if the shiny object is supersonic.
I remember reading a SciFi book once about war in 2020 where the new apache like helicopter had smoke chaff of dust born particles to scatter the laser light of attacking craft trying to melt them.
I think that would be the only reasonable defense.
Of course you really wouldn't be able to see anything yourself and if it was really windy or you were moving really fast it wouldn't work.
Nor would it really be feasible with the whole turbulence from the chopper itself... Well it was an ok book.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
He never described how the zero sum wars were being fought, only that they were.
Well it really depends on the the power density in the beam. If a target is 90% reflective to the the wavelength used by the laser, then the laser would have to be 10 times more powerful to achieve the same heating in the target. My guess is that polished aluminum might maintain 90% reflectivity, but who knows. Of course, a speck of highly absorbing dust will burn very quickly, subsequently, the burned area around the dust will also begin absorbing so a hole may grow very quickly. The question is then: how long can the laser remain focused on the burning patch? If it wanders due to atmospheric disturbance the spot may not cause a failure of the target.
Here's the real problem. If you make the laser so powerful that a bit of dust will cause a significant burn to start, a speck of dust on your targeting optics will obliterate the laser platform itself. You could manage this by using a very large targeting mirror and focusing onto the target (possibly what the system does but I couldn't be bothered to look it up) but then you need accurate range-finding as well as directing and you need to keep the beam targeted precisely enough to hit a small focal point for an extended (probably still less than a second) period of time .
At the end of the day the whole system is damn hard to get working. Targeting an enemy missile rather than a slow-moving drone may still be an unsurmountable challenge. I suspect that the whole system is a giant waste of money made even more expensive by the possibility of shiny targets.
So if this is the future...where's my jet pack?
The topic of discussion was the radiation pressure of the laser. ByteSlicer was hypothesizing that a laser this powerful would have enough momentum to destroy things just with that, but they are quite wrong.
The actual energy of the laser ("mega-watt class" according to tfa) is of course sufficient to cause significant damage; the whole point of this demonstration. But it's not doing it's damage by the photons imparting their momentum to the target. ;)
The enemies of Democracy are
Well, we are talking about the properties of mirrors being exposed to high energy lasers. What research are you referring to by the way? Any links?
Yes, you keep saying that. Do you expect people to take your word for it (especially considering you admit to not being an expert)?
Sure, but all this is meaningless without numbers. How rapidly? How long is the laser pulse?
If a cannon (of any technology) dumps it's energy near you, you die. It doesn' much matter whether the laser cannon heats the skin of the missile, or the air next to it, to plasma temperatures, it's enough to destroy the missile. These weapons are not intended to be energy efficient, they're intended to reach a fast-moving target quickly. For example, an ICBM boosting to orbit is a clear and obvious target, but you can't catch it with a missile - it's already the fastest missile there is. But you can easily tag it with a laser.
Socialism: a lie told by totalitarians and believed by fools.
Current chemical lasers suck for firing at low-value targets. The fuel is massive and incredibly toxic. It's worth using 300 pounds of fuel to take a shot at a boosting ICBM, but not so much at a UAV. However, that's just a fuel source, and not the core part of the weapon technology. An electrical laser would be dandy for defending equipent that naturally generates power from UAVs. And shooting down boosting ICBMs is becoming more valuable as more countries gain access to those.
Socialism: a lie told by totalitarians and believed by fools.
You don't fight fair -- you fight to win. We used to understand that. Our enemies still do.
And what exactly is a "win" in the context of afghanistan? We need to make sure that whatever we do to "win," whatever that even is in this context, doesn't create more enemies.
www.justfuckinggoogleit.com
You can disprove his assertions, or you can just be a dick.