# So, they shot down artillery with a laser **URL:** \ **Category:** Factual Questions\ **Created:** [November 6, 2002, 6:43pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589 "2002-11-06T18:43:33Z")\ **Posts on this page:** 19\ **Page:** 2
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [November 8, 2002, 9:05pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/21 "2002-11-08T21:05:54Z")
> [@](#): > > _Originally Posted by ZenBeam_ > This is true at sufficient distance from the laser, but “sufficient distance” is on the order of D2/ lambda where D is the diameter of the source, and lambda is the wavelength You are, of course, correct. The relationship which governs the beam radius is: w(z)=w[Sub]o[/Sub](1+(z [Symbol]l[/symbol] / [symbol]p[/symbol] w[sub]o[/Sub][Sup]2[/Sup] )[Sup]2[/Sup])[Sup]½[/Sup] Where z is the distance from the beam waist (w[Sub]o[/Sub]). Using this I get the beam doubles after 989 meters using your numbers, or just less than 1 km. This means the power/area in the beam has been reduced by a factor of 4 after 1 km. > [@](#): > > _Originally Posted by SenorBeef_ > Hitting artillery shells is certainly not a mature science. I’m curious about this and must admit I know nothing about it. Iwould think though that building a camera that tracks an object and keeps it in the center of the image cannot be too hard (as long as there is good contrast between the background and the object). Once you have the camera, it shouldn’t be too hard to hit the object with a laser (just bolt the thing to the camera and make sure it’s properly aligned). Does anybody know if this is possible? Another thing, does anybody know how much power is required to destroy a missle within an order of magnitude or so? ---
**Author:** ![nth](https://avatars.discourse-cdn.com/v4/letter/n/58956e/32.png) [@nth](https://boards.straightdope.com/u/nth)\ **Post date:** [November 8, 2002, 10:13pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/22 "2002-11-08T22:13:41Z")
huh? i dunno anyone who can pan a camera to a speeding bullet. ain’t that what is required? you can take pictures of bullets by guessing when the bullet will pass your view. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [November 8, 2002, 10:40pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/23 "2002-11-08T22:40:10Z")
> [@](#): > > _Originally Posted by nth_ > huh? i dunno anyone who can pan a camera to a speeding bullet. I was thinking of something like [this](http://www.caravan-ny.com/projectile_tracking_systems.htm). I have no idea how reliable they are though, or what the maximum speed or minimum size of the projectile they can track is. Anybody know how well these type of systems work? ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [November 8, 2002, 10:43pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/24 "2002-11-08T22:43:47Z")
**Eyer8** , better double check your numbers. w[sub]0[/sub] = 0.1 m lambda = 5500 \* 10[sup]-10[/sup] = 5.5E-7 m The beam doubles when z \* lambda / (pi \* w[sub]0[/sub][sup]2[/sup]) = sqrt(3) or z = sqrt(3) \* w[sub]0[/sub][sup]2[/sup] \* pi / lambda = 98.9 kilometers. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [November 8, 2002, 11:32pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/25 "2002-11-08T23:32:41Z")
DOH! I used w[sub]o[/sub] = 0.01 m. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 9, 2002, 3:24am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/26 "2002-11-09T03:24:21Z")
There’s a little more on how the test was done in this [AP story](http://story.news.yahoo.com/news?tmpl=story&ncid=528&e=3&cid=528&u=/ap/20021108/ap_on_hi_te/laser_weapons). > [@](#): > > The shell, moving at about 1,000 mph, was tracked by radar and heat-sensing infrared sensors, then locked onto and zapped by the laser beam traveling at light speed. No explanation is provided as to why they need two types of sensors. Perhaps the IR is really part of an adaptive optics system like that used in the airborne laser ? ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [November 9, 2002, 4:02am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/27 "2002-11-09T04:02:34Z")
Did they mention anything as to number of these “interceptors” they have, placements of “interceptors” and the gun, etc.? ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 9, 2002, 4:24am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/28 "2002-11-09T04:24:53Z")
> [@](#): > > \*Originally posted by Eyer8 \* > \*\* > > I’m curious about this and must admit I know nothing about it. Iwould think though that building a camera that tracks an object and keeps it in the center of the image cannot be too hard (as long as there is good contrast between the background and the object). Once you have the camera, it shouldn’t be too hard to hit the object with a laser (just bolt the thing to the camera and make sure it’s properly aligned). Does anybody know if this is possible? > > \*\* Well, no technology has ever been developed, until now, meant for destroying artillery shells in combat. This is the first experimental weapons system to take that on, as far as I know, and so I’m saying it’s not a mature science. Tracking them is - we’ve had counterbattery radar for decades - but actually shooting them down is something new. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [November 9, 2002, 6:31am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/29 "2002-11-09T06:31:55Z")
> [@](#): > > \*Originally posted by SenorBeef \* > \*\*Well, no technology has ever been developed, until now, meant for destroying artillery shells in combat. This is the first experimental weapons system to take that on, as far as I know, and so I’m saying it’s not a mature science. Tracking them is - we’ve had counterbattery radar for decades - but actually shooting them down is something new. \*\* Not so; the [Phalanx Close-In Weapon System](http://216.239.33.100/search?q=cache:czAKClb5arEC:www.xi.hq.af.mil/af_xi_docs/XIW/Innovpanel/fy02-actd/55%2520Frangible%2520Round.doc+phalanx+artillery+ciws&hl=en&ie=UTF-8) has been tracking and knocking down artillery shells for 20 years: > [@](#): > > **The U.S. Navy Phalanx Close-In Weapon System (CIWS) routinely uses artillery projectiles as test targets, tracking the projectiles with its radar and Forward Looking InfraRed (FLIR) camera. The Phalanx CIWS typically hits the incoming artillery projectiles with from 2 to 8 Armor-Piercing Discarding Sabot (APDS) projectiles during each engagement.** ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 12, 2002, 11:36am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/30 "2002-11-12T11:36:25Z")
Strange, I posted a reply to this yesterday but it never went through. I’ve read up quite a bit on the phalanx system, and never read about it being used to shoot down shells in flight. Your link is broken, so I’m not sure what that would say. If it did do that, though, it was probably strictly under test conditions with a modified shell to aid tracking or something similar. If the phalanx had the ability to shoot down shells in a combat environment, it most certainly would’ve been employed that way, I think. As far as I know, we have no weapons system that even tries to destroy incoming artillery shells in a combat sense, and so I’d still say it wasn’t a mature science. ---
**Author:** ![Diceman](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Diceman](https://boards.straightdope.com/u/Diceman)\ **Post date:** [November 12, 2002, 12:40pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/31 "2002-11-12T12:40:52Z")
I have to side with the skeptics. Given the rigged ABM tests, I’m inclined to believe that the shell had a guidance system, or that the laser was already pointing right at the correct spot. If you want to convince me, set it up so you have a dozen artillery pieces in different locations, loaded with unmodified shells such as an enemy might use. Set up a target that the laser is supposed to defend. Tell the guys running the laser that sometime within the next 48 hours one of those cannons will shoot at the target. Then let’s see if the laser can lock onto the shell and shoot it down. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [November 12, 2002, 3:55pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/32 "2002-11-12T15:55:32Z")
> [@](#): > > \*Originally posted by SenorBeef \* > \*\*I’ve read up quite a bit on the phalanx system, and never read about it being used to shoot down shells in flight. Your link is broken, so I’m not sure what that would say. > > If it did do that, though, it was probably strictly under test conditions with a modified shell to aid tracking or something similar. If the phalanx had the ability to shoot down shells in a combat environment, it most certainly would’ve been employed that way, I think.\*\* The Phalanx CIWS is perfectly capable of being used to knock down artillery shells in combat. This has been demonstrated with production models, not test beds, in systems placed on naval vessels. The only problem is the depleted uranium bullets that it employs; in in a battlefield environment, they were judged to be a risk to personnel in the area. My link (which works for me) investigates ways to mitigate this drawback with a self-destructing round designed for anti-artillery use in battlefield conditions: > [@](#): > > \*\*While these impacts are sufficient to destroy the incoming artillery projectiles and missiles, the Phalanx CIWS system is presently not seen as providing the close-in protection layer for fixed site US Army assets due predominantly to the Fall-of-Shot of APDS projectiles which fail to impact the incoming artillery projectile. Those APDS projectiles can pose a serious threat to friendly forces when their trajectory causes them to return to earth. > > … > > Development of a “Frangible” self-destruct (FS-D) tungsten penetrator for defeat of artillery projectiles in defense of a fixed asset would have the benefit of providing the required protection for fixed assets while preventing potential fratricide posed by a typical APDS projectile returning to ground. The requirement would be for the FS-D penetrator to retain structural integrity long enough to penetrate and destroy the artillery projectile, but if it misses, self-destruct. This self-destruct sequence can be initiated by a small fuze that detonates a small internal charge integral to the FS-D projectile. This self-destruct mechanism effectively disintegrates the round, returning it back into the tungsten powder from which it was originally made from. > > … > > The operational concept is to provide a minimum of one Phalanx Block 1B CIWS per fixed site (depending on the area to be defended), strategically placed to provide protection from the expected threat axis. The Phalanx CIWS would operate normally in that it would search for threats that can impact its “Protected area”. When it detects a threat, in this case an artillery projectile, it will track the target with both its track radar and FLIR. At the appropriate engagement window, it opens fire (4500 shots per minute) on the projectile coming in on its ballistic path. FS-D projectiles that impact the target would penetrate through the steel case and cause detonation of the high explosive inside the artillery projectile. Upon detecting the detonation, the Phalanx CIWS would return to searching for additional projectiles and conduct similar engagements against any other threats to its defended area. Projectiles that fail to impact a target would be rendered harmless by the self-destruct fuze after flying its preset distance. > > \*\* ---
**Author:** ![johncole](https://avatars.discourse-cdn.com/v4/letter/j/5f9b8f/32.png) [@johncole](https://boards.straightdope.com/u/johncole)\ **Post date:** [November 13, 2002, 3:56pm UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/33 "2002-11-13T15:56:20Z")
> [@](#): > > \*Originally posted by SenorBeef \* > > * * * > > ## \*Originally posted by Squink \* against katyusha missiles in 2000. > > \*\* > Nit: Being unguided, the Katyushas are rockets, not missiles. \*\* Nit-Nit: Katyushas are both rockets _and_ missiles. **Rockets** are defined as rockets because they use rocket propulsion - they can be guided or unguided. **Missiles** are any object or weapon that is thrown at a target or shot or launched from an engine, gun, etc. (Collins English Dictionary) When they are guided they are called **guided missiles**. When they are unguided they are called **ballistic missiles**. An artillery shell and a dart are both ballistic missiles. A Katyusha is a ballistic missile. Seawolf (a fully automatic, fast reaction, high speed, point defence missile system in use by the Royal Navy) is a guided missile that has been credited with intercepting a ballistic missile (a 4.5" naval artillery shell) during proving trials.[cite](http://web.ukonline.co.uk/aj.cashmore/.weapons/uk/.sam.html) ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 15, 2002, 5:33am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/34 "2002-11-15T05:33:13Z")
> [@](#): > > \*Originally posted by johncole \* > \*\* > Nit-Nit: > > Katyushas are both rockets _and_ missiles. \*\* Sort of. The US military uses it’s own definition between the two, which don’t always match dictionary definitions. > [@](#): > > \*\* > **Rockets** are defined as rockets because they use rocket propulsion - they can be guided or unguided. \*\* In US military terms, rockets are always unguided. > [@](#): > > \*\* > > **Missiles** are any object or weapon that is thrown at a target or shot or launched from an engine, gun, etc. (Collins English Dictionary) \*\* In US military terms, I’m pretty sure missiles are always guided. > [@](#): > > \*\* > When they are guided they are called **guided missiles**. > > When they are unguided they are called **ballistic missiles**. \*\* Not true - ICBMs, intercontinental ballistic missiles, for example, are guided. And that’s what I thought at first too - that the “ballistic part” meant that they had no guidance system - and that’s when I learned that US military definitions are different from Websters, etc. They’re “ballistic” bacause of the path they take. As opposed to cruise missiles, etc. > [@](#): > > \*\* > An artillery shell and a dart are both ballistic missiles. > > A Katyusha is a ballistic missile. > > Seawolf (a fully automatic, fast reaction, high speed, point defence missile system in use by the Royal Navy) is a guided missile that has been credited with intercepting a ballistic missile (a 4.5" naval artillery shell) during proving trials.[cite](http://web.ukonline.co.uk/aj.cashmore/.weapons/uk/.sam.html) \*\* They designed a missile to take down artillery shells? Odd. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 15, 2002, 5:34am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/35 "2002-11-15T05:34:28Z")
Er, also, the Katyusha is a rocket in US military terms. Forgot to address that point specifically. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 15, 2002, 5:35am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/36 "2002-11-15T05:35:36Z")
Stupid me, I should read more closely (and stop making multiple posts) - you meant (I assume) that the missile shot down an artillery shell in trials, not that it was designed for it. ---
**Author:** ![johncole](https://avatars.discourse-cdn.com/v4/letter/j/5f9b8f/32.png) [@johncole](https://boards.straightdope.com/u/johncole)\ **Post date:** [November 16, 2002, 12:05am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/37 "2002-11-16T00:05:01Z")
> [@](#): > > \*Originally posted by SenorBeef \* > \*\*Er, also, the Katyusha is a rocket in US military terms. Forgot to address that point specifically. \*\* Yup, agree entirely - said that in my post. It is a rocket because it uses rocket propulsion, but that does have any bearing on whether it is guided/unguided. > [@](#): > > **Not true - ICBMs, intercontinental ballistic missiles, for example, are guided. And that’s what I thought at first too - that the “ballistic part” meant that they had no guidance system - and that’s when I learned that US military definitions are different from Websters, etc. They’re “ballistic” bacause of the path they take. As opposed to cruise missiles, etc.** In your own words “they’re ballistic bacause of the path they take”. The term “ballistic” means that they are moving “under their own momentum and the force of gravity”. At that point they are unguided because guidance would require some other force to act on the missile. The fact that somebody coined the inaccurate term ICBM when they are only ballistic missiles during the mid part of their flight does not invalidate the original meaning of the words, or their application to rocks, shells, eggs, etc. (and I suspect that the early forms of ICBM were not capable of manoeuvering on reentry). I cannot comment on the specific meanings that the US military apply to certain words (but I am happy to take your word for it). IMO the narrow meanings applied by any organisation to well-defined words in common use cannot be allowed to limit the use of the established definitions. I am not against jargon, it is a valuable technique _in its proper place_ (i.e. when extreme precision of expression is required) but many organisations (and the US military is not the worst offender) go to extreme lengths. In my world a spade is a shovel, not a manually operated earth moving implement. > [@](#): > > **you meant (I assume) that the missile shot down an artillery shell in trials** Assumption correct, but I have often wondered _why_ they used a shell as a test target. Probably because it was cheaper than a drone. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 16, 2002, 12:39am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/38 "2002-11-16T00:39:55Z")
> [@](#): > > IMO the narrow meanings applied by any organisation to well-defined words in common use cannot be allowed to limit the use of the established definitions. To do so might even be seen as [Snark](http://www.robsv.com/cape/c1lv.html)y, and that’s a rocket assisted, jet powered, nuclear-tipped intercontinental cruise missile of an entirely different color 😃 ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 16, 2002, 7:08am UTC](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589/39 "2002-11-16T07:08:24Z")
You’re entirely right by common dictionary definitions, but the US military’s naming system is consistent, if different. [Previous page](https://boards.straightdope.com/t/so-they-shot-down-artillery-with-a-laser/135589.md?page=1)