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Thread: Effective range of laser weapons in space?

  1. #1 Effective range of laser weapons in space? 
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    In almost every SciFi laser weapons are the ''snipers'' of space combat due to their lightspeed photons doing the damage but space conducts heat pretty badly and there's still some atoms in the ''vacuum'' of space to cause diffraction, so what is the effective range of laser weaponry in space? 300000km, 3000000km?


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    I don't know the exact answer, but laser light will diverge on its own. The light won't stay bunched up; at least that's what I read somewhere. When they laser range the moon spreads out over wide area.


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    Quote Originally Posted by Tyzuris Coronati View Post
    so what is the effective range of laser weaponry in space? 300000km, 3000000km?
    Among other things it depends, heavily, on the size of the focussing equipment (diameter of the mirror).
    You might want start here, or get a hold of a back issue 1 of Challenge where an extensive mathematical treatment was given on that very subject.

    1 Can't remember which issue, and I'm not trawling through 53 copies just to find it right now. But, IF I remember I'll dig it out and maybe send you a PDF of the relevant article if you want.
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    Forum Radioactive Isotope cosmictraveler's Avatar
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    What good Is a laser when all you'd need to do Is use reflective material on the hulls of ships. Another thing Is that the power needed to generate enough energy to make any laser "destructive" at any distance Is tremendous.
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    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by cosmictraveler View Post
    What good Is a laser when all you'd need to do Is use reflective material on the hulls of ships.
    Common misconception.
    Lasers cause massive thermal (and therefore mechanical) shock.
    The proposed SDI (Star Wars 1) orbital lasers required (from memory) 1 tonne of liquid hydrogen per second to prevent the focussing mirrors shattering.

    Another thing Is that the power needed to generate enough energy to make any laser "destructive" at any distance Is tremendous.
    But it gets focussed.

    1 The Reagan version, not George Lucas'.

    ETA: and what reflects (if we go high-tech) X-ray lasers?
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  7. #6  
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    Quote Originally Posted by Dywyddyr View Post
    Lasers cause massive thermal (and therefore mechanical) shock.
    Agreed - but that is due to energy absorbed. A perfect mirror would not absorb any energy from a laser. Since there are no perfect mirrors, you can always choose a power level that will be destructive for any given object.
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    Forum Radioactive Isotope cosmictraveler's Avatar
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    However the distance at which lasers work Is relatively short usually under a mile. The farther away an object is the more power you'll need to make the laser effective.
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  9. #8  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by cosmictraveler View Post
    However the distance at which lasers work Is relatively short usually under a mile.
    Because of:
    A) the atmosphere 1 - not a problem in space combat.
    B) Focussing optics size - a vehicle (or even ship) mounted weapon has limited space to fit it.
    C) Initial power: current lasers are relatively low powered because there's little space to fit the generators - we'd use more space for these IF we'd developed more reliable weapons. They are, to date, seen as secondary systems. If ever they achieve the reliability and consistency of, say, a 5 inch gun then they'd have more on-board resources allocated.

    The farther away an object is the more power you'll need to make the laser effective.
    Or better optics.

    1 IIRC a 1970s German/ American study showed that, with a free electron laser there's a 30% loss of power per mile in atmosphere at (or close to) the surface of the Earth. (It was a study for anti-helicopter defence).
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  10. #9  
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by Tyzuris Coronati View Post
    so what is the effective range of laser weaponry in space? 300000km, 3000000km?
    Among other things it depends, heavily, on the size of the focussing equipment (diameter of the mirror).
    You might want start here, or get a hold of a back issue 1 of Challenge where an extensive mathematical treatment was given on that very subject.

    1 Can't remember which issue, and I'm not trawling through 53 copies just to find it right now. But, IF I remember I'll dig it out and maybe send you a PDF of the relevant article if you want.
    I'd appreaciate the PDF article and PM me and I'll tell you my e-mail to which you can send the PDF.
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  11. #10  
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    Quote Originally Posted by cosmictraveler View Post
    What good Is a laser when all you'd need to do Is use reflective material on the hulls of ships. Another thing Is that the power needed to generate enough energy to make any laser "destructive" at any distance Is tremendous.
    Yep. Spinning a reflective missile was even more effective. There were a number of papers from the 80's talking about how rediculous many of the DSI concepts were because they violated the laws of physics...but like now no one could be confused by the facts. Effective deep underground Bunker busters are another mythology that grew up around that time.
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    I heard that the most powerful laser to shoot 100 km airspace.
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    Quote Originally Posted by smartkensol View Post
    I heard that the most powerful laser to shoot 100 km airspace.

    With no destructive power to do harm to anything except people looking directly into it.

    2013....

    GERMAN MILITARY LASER DESTROYS TARGETS OVER 1KM AWAY


    A German company has brought us one step closer to the kinds of shootouts only seen in Sci-Fi films. Düsseldorf-based Rheinmetall Defense recently tested a 50kW, high-energy laser at their proving ground facility in Switzerland. According to the company, the laser passed the test with “flying colours.”

    The system isn’t actually a single laser but two laser modules mounted onto Revolver Gun air defense turrets made by Oerlikon and attached to additional power modules. The laser modules are 30 kW and 20 kW, but a Beam Superimposing Technology (BST) combines two lasers to focus in a “superimposed, cumulative manner” that wreaks havoc on its targets.

    First, the system sliced through a 15mm- (~0.6 inches) thick steel girder from a kilometer away. Then, from a distance of two kilometers, it shot down a handful of drones as they nose-dived toward the surface at 50 meters per second. The laser’s radar, a widely used system called Skyguard, was capable of tracking the drones through their descent up to three kilometers away.


    https://www.google.com/url?[/SIZE]<b...EtIWi5ntQnoXZw


    Up to three miles isn't very far and if a stealth missile was heading your way it couldn't be seen by radar as todays planes cannot be seen that are stealthy.[/FONT][/COLOR]
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  14. #13  
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    Quote Originally Posted by Dywyddyr View Post
    ETA: and what reflects (if we go high-tech) X-ray lasers?
    "An X-ray mirror optic for NuStar space telescope working up 79 keV, was made using multi-layered coatings, computer aided manufacturing, and other techniques.[12]The mirrors use a Tungsten (W)/Silicon (Si) or Platinum(Pt)/Silicon Carbide(SiC) multi-coating on slumped glass, allowing a Wolter telescope design.[12]"

    X-ray optics - Wikipedia, the free encyclopedia


    Wolter telescope - Wikipedia, the free encyclopedia
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  15. #14  
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    Quote Originally Posted by Tyzuris Coronati View Post
    In almost every SciFi laser weapons are the ''snipers'' of space combat..

    It's kind of funny that people think that.

    Really projectiles are better for sniping than lasers because, in space, they have an effectively unlimited range. The only limitation on their range is the ability to accurately aim the shot (which would be a limitation for lasers also.)

    Lasers, on the other hand, are limited by how focused they are. It's unlikely you'd ever build a laser that was small enough to mount on a ship and be able to fry something from more than a few hundred kilometers away.
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    Most powerful laser is located on U.S. military plane. It can destroy a missile at a distance of 100 km.
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    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by smartkensol View Post
    Most powerful laser is located on U.S. military plane. It can destroy a missile at a distance of 100 km.
    Nonsense.
    The ABL may be the most powerful airborne laser, but the COIL (Chemical oxygen iodine laser) is "only" 380 kiloWatts [output], oh, and it stopped flying in 2012.
    Meanwhile, back on the ground there's a petawatt laser...
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    Long-range lasers consume too much energy. Therefore, the military refused them.
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  19. #18  
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    Quote Originally Posted by smartkensol View Post
    Long-range lasers consume too much energy. Therefore, the military refused them.
    You're exhibiting some confusion here.
    The military hasn't refused them - the US Navy is currently getting ready to deploy a laser weapon.
    And "consume too much energy" is a relative thing.
    If you have the on board capability to generate more energy that the laser requires then they obviously don't "consume too much".
    Like all weapons (in fact all systems) it's a trade-off.
    End result is weighed against power available, space, tonnage, manning, cost ... etc etc.
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