How to create 'visible' space-laser-like weapons

Goal:

Just imaging a Star Wars X-Wing fight, and you've got the idea. However, I want to know whether something like that is possible without tons of metaphysical hand-waiving and 'just because'.

What I've figured out so far:

• Sound can be an auxillary computer program to help the pilot process information when he's too busy looking at the radar / sensor read-outs (i.e. the computer creates sound effects according to what the sensors say, kind of like the parking help in cars nowadays).

• You could perhaps make use of that technique to make otherwise invisible weapons fire visible (i.e. creating a projection on the screen of the trajectory).

• Lasers are out. For one, I want a fight where the opponent has to come within a humanly visible range when they want to make effective use of their weaponry. This question gives a ball-park figure that nowadays, a 300km distance is easily within reach of a weapons-grade laser. For another, lasers are instantaneous at such short distances. Even when using the computer-assisted screen rendering, it would look like a solid line from start to end that briefly blinks into existence (= undesired visiual effect, not to mention whether it is even possible to detect a laser not targeted directly at oneself). For another, I do want my pilots to have some warning that they are being attacked before they have a nice coin- or football- or ship-sized hole in their ship.

Question

Is there a kind of physically possible weapon that could satisfy my requirements:

• detectable by sensory equipment before impact
• flies at a speed where human reaction time can save one's bacon from a distance of 1km
• does not have any intelligence capability (i. e. no heat-seeking missiles)
• can be mounted on single-person space fighters
• can actually cripply or destroy another single-person space fighter within a couple of shots

Could something as mundane as bullets satisfy the requirements? What about the recoil?

Bonus Questions

Is there a shielding possibility that doesn't involve sacrificing heavy armor plates?

Why the frag did my space fighting race not go for lasers in the first place?

• So in short you want beam weapons that can be seen or at least detected and artificially visualized. Well... shoot anything that glows or shines then... plasma bursts would do that. Neutron beams could do it as well because free neutrons decay (half-life of 10.2 minutes), and the radiation from decaying neutrons can be detected and visualized. – MichaelK Apr 1 '16 at 10:50
• Well, it would be nice if it could be a beam weapon, but I'd also be satisfied with projectile weaponry if it actually fits the requirements and nothing else works. (Would be kind of hilarious to know that Star Wars is actually being fought with Bullets in Space and tons of artificial visualization) – subrunner Apr 1 '16 at 11:08
• I have edited my answer, maybe you would like to revisit it. – mg30rg Apr 1 '16 at 14:56

JordiVilaplana's answer about plasma is flawless, but I would like to extend it some more.

In addition to high speed plasma, two I can imagine two other kinds of space weapons that fulfill your criteria:

Railgun:

A railgun uses an electromagnetic system to accelerate a piece of metal (preferably something quite heavy and durable like tungsten) to very high speeds (from a few thousand km/h to relativistic speeds - in your case the lower the better), and during this acceleration the piece of metal gets heated to an enormous temperature, so it's shining hot. I think bolts of shining hot metal would very much like blaster rounds from Star Wars.

Regular guns with tracer ammo:

(You might watch a video for better understanding. Edit: Here is a better video thanks to @AndyD273)

Tracer ammunition are bullets or cannon caliber projectiles that are built with a small pyrotechnic charge in their base. They are fired from regular guns and built to leave cartoon-like light traces mid-air.

Bonus: why would you use tracer ammo? To ease targeting. You see space is big - I mean really big - and your target is relatively small. If you want to hit it from a km or so with a round that only goes with like 6-800 m/s, you should fire plenty of them and you should be able to track their general trajectory.

On shield technology:

I would vote for an SF-solution in this case, namely nanotechnology. With nanotechnology, you can (theoretically) create a diamond-firm layer of nanobots around your vehicle (even a transparent one), which can repair itself as long as you can provide "shield-energy" and replacement nanobots.

Why not lasers:

The short answer is that no matter what sf told us lasers suck at space fights. Lasers are electromagnetic radiation, so they lose energy according to the inverse square law. which means a laser which is deadly from 100 meter is only a joke from 200m and can barely be seen from 2km, while a physical projectile which causes the most harm using dynamic energy will practically lose no energy with the trip it does.

• Another video: Minigun on a helicopter with tracers. I think only every 100th round is tracer, but at 3000 rounds a minute it kind of doesn't matter. You wouldn't want every round to be a tracer at that rate of fire since tracers cause extra wear on the barrel. – AndyD273 Apr 1 '16 at 16:15
• Lasers don't lose energy according to the inverse square law, they lose power. If you're hitting a point target, these act as one and the same, if you're hitting an object with surface area, it will disperse the energy over a larger portion of the target, but all the energy will hit the target. If all you need to do is melt a hull panel, you may get away with more dispersion than if you have to vaporize a pencil hole through it. – Cort Ammon Apr 1 '16 at 18:05
• Its a very modified inverse square law because instead of radiating in all directions it is a cone. It is even more modified if the emitter is focusing the beam at the target location, in which case instead of spreading out, it is narrowing down, but will of course start to spread after the target point. – Zan Lynx Apr 1 '16 at 22:11
• @Zan Lynx - Instead of using a lens to focus rays to a point, you can also put it at just the right distance from the laser to get the rays to leave traveling approximately parallel, as in the top diagram on this page--in an idealized case where all the rays originally come from a point source there'd be no divergence past the lens at all, but all real sources have some finite width which means there'll be some divergence as noted here. – Hypnosifl Apr 2 '16 at 3:29
• Awesome idea with the tracer rounds! I think I'll stick to a combination of RailGun and Tracer rounds! Not quite sure about the SF Shielding solution, and I don't think the laser dissipation works the way you described (the other comments pretty much said all my issues with it), but kinetic projectiles seem to be my only solution here. Thank you very much!!! – subrunner Apr 14 '16 at 11:18

PLASMA CANNONS

Which are, actually, the technology behind the Star Wars blasters. I think it fits all of your requirements:

• It is easily detectable due to its "bullet's" high thermal signature.
• It can fly at whichever speed you want, even a 9mm gun's bullet will give you about 1s until it hits you if fired at 1km. But you have to see it coming and remember: the faster, the better.
• A plasma blast is like a bullet, you fire it in straight line, it has no guidance system.
• If technology is advanced and miniaturized enough, you can even build hand guns.
• It depends not only on the cannon, but on the target's defenses. Shoot 1oz of carbon plasma to a 1m thick steel shield and you will do almost nothing. Shoot 1lb of iron plasma to a rabbit and you will delete it from existence.

Unfortunately, a plasma blast is not like a bullet or a slingshooted pebble, it's not just its kinetic energy what you must worry about. A plasma blast is a bunch of concentrated and ionized high temperature matter, so it can melt your starfighter's hull and make some electromagnetic disorders.

Heavy armor plates would be effective against small blasts, but they can still get heat up if hit by many blasts, so I would add two improvements:

• EM shields: A strong enough electromagnetic field around the space fighter should be able to deflect the plasma blasts.
• Internal Heat Cycle System: In space there is no air that can cool down your ship, but you need to spread the heat in the hit area to minimize its effects. Place a pipeline of cooling fluid through your hull.

For sure a plasma blast requires more energy than a laser beam, but it is much more effective. Maybe your space armies began using laser weapons, and maybe they ended up with fancy mirror hull spaceships. Then some genius tried to fire a plasma blast to a spaceship and earned much more than 7 years of bad luck as the ship's mirror hull gained a not-so-fancy hole.

• Sounds like a really great solution! Just out of curiosity - just why should my space-fighter scientists not make the plasma bolts a lot faster so that the 'react-in-time-from-1km' property is violated, e.g. not Mach 3 but Mach 30 or 300? – subrunner Apr 1 '16 at 11:23
• @subrunner Because the energy required to increase the muzzle speed of the cannon increases with the square of the speed, so your scientists should find an equilibrium between low energy consumption and high blast momentum. – JordiVilaplana Apr 1 '16 at 11:57
• Is a plasma cannon a real technically possible weapon? What would prevent the plasma from dissipating immediately once it left the "barrel", like what would happen if you tried to shoot a bullet made of gas in a vacuum? If the beam is dense/hot enough for particles in the beam to collide with one another as they travel, that should give them somewhat random velocities in the direction perpendicular to the beam, making the beam spread out...seems like you'd either need very low density (maybe making it invisible) or extremely cold particles (so in one's rest frame the others are hardly moving) – Hypnosifl Apr 1 '16 at 14:00
• Plasma can be considered a gas so super heated, that some of its electrons have shaken loose. Now stick that super heated gas into a vacuum. What happens? In space, the plasma from a "plasma cannon" immediately flies off in all directions and dissipates. Under certain circumstances it is possible to make a plasma cannon like you envision work in an atmosphere but not in space. – Jim2B Apr 1 '16 at 14:08
• Short answer is either "no" or "it isn't worth the effort." This is especially true because at orbital speeds, getting hit by that solid core will be far more devastating (more mass & therefore more energy) than being hit by the plasma it's trying to corral. – Jim2B Apr 1 '16 at 19:29

For a primer on space combat and weaponry go read Atomic Rocket's: Space War and the follow-up materials on the weaponry. In fact, you should do that before you read any more of my answer.

A quick summary of the science is:

1. Fighters are unrealistic
2. Stealth is unrealistic
3. Shields are unrealistic
4. Armor is not practical
5. Weapons all come from 2 basic forms (directed energy or projectile) with lots of variety.

I am going to challenge you on your constraints (e.g. no lasers). I think there could be a way to get what you want and keep those in.

On Weapons

There will be two main categories of weapons, directed energy weapons (this includes lasers) and projectile (this includes guns, missiles, and anything else that is not a directed energy weapon).

Lasers

Most of what I have to say about lasers applies equally well to other types of directed energy weapons (e.g. particle beams of various types).

Forget everything you've seen in SciFi about space lasers. The most effective laser is one that has lots of power and a large primary mirror to focus the beam at a distance. So a Traveler RPG type "spinal mounted" laser with two pop-up turrets (one on each side of the ship) might be the way this is accomplished. This gives you 1 lasing cavity with two apertures. One can be doing target tracking while the other handles the shooting.

The "spinal mount" might be a Free Electron Laser (FEL) so that you can tune the laser to any wavelength (e.g. for beam reasons, this will probably be X-Ray). You might get an effective kill shot on a ship of the same size all the way out to 1 light-minute distance (11 million miles or 18 million km).

The beam travels at the speed of light (or for particle beams, close enough that you'd have a tough time telling the difference). The targeting is only as good as the physics allows. Meaning at 1 light minute distance, your target has 2 minutes to get out of the way of your incoming fire.

Projectile

Projectiles actually covers a couple of different groupings. Weapons with propulsion and guidance and those without. You might call weapons with low thrust but high $\Delta V$ torpedoes and weapons with high thrust but low $\Delta V$ missiles. Both would require guidance.

To ensure a near miss would still kill the target, most of these will include a nuclear warhead. Note a 1 km miss with a nuclear warhead means no damage to the target. You might even miss by 100 m and not inflict significant damage (depending upon warhead size).

An alternative to projectiles with propulsion and guidance would be completely dumb projectiles. All of these (chemical powered ones, gauss/coil guns, rail guns, gas guns, etc.) might be classified as "guns". The problem with these is that they're really only good for close range. Against a maneuvering foe at a 1 light-minute range you have almost no ability to hit a target with them - no matter how good your computer targeting is.

An alternative to fighters

The Atomic Rocket's site states that fighters don't make sense. The pilot actually significantly reduces the survivability of the platform. However, the concept of fighters still makes sense: project weapons into locations too dangerous for your big space cruiser.

So they use the idea of a Kinetic Kill Vehicle Bus. It's a "missile bus" that drives the passenger missiles into an engagement envelope so that the missile's on board propulsion and guidance can complete the intercept of the enemy ship.

• It's possible the KKV bus uses a low thrust high $\Delta V$ engine while the missiles provide a high thrust, low $\Delta V$ engine for the terminal maneuvers.
• It's possible the KKV bus provides extra computing power and penetration aids to distract your target's defensive systems.
• It's possible the KKV bus provides telemetry and recon information back to the mother ship. Which makes it valuable in the battle even after it flies past the target ship.
• It's possible that the KKV bus may also attempt a target intercept if the target is in the KKV bus engagement envelope.

Regardless of what you put on it, the KKV bus is on a one-way journey. The energy costs of getting it to return would be too high. If you read the Honor Harrington books, this would be very similar to the "Apollo" which they launch with their missile salvos as a control node.

A KKV bus has several advantages over "space fighters" and shares all the advantages of a manned "space fighters". The first is that they can maneuver at significantly higher accelerations than any manned craft - possibly up to the 10,000 g accelerations. They don't need to carry any of the life support equipment to keep a human alive. Best of all, they don't need any equipment for recovery, each is expendable with all that means for performance, size, cost, etc.

Using a KKV bus to deliver a MITW (multiple independently targeted weapons) instead of just launching those weapons en mass has some advantages. The first is that the vehicle can carry extra equipment to improve the performance of those missiles (sensors, penetration aids, communications, etc.). The second is that for engagements with unfavorable kinematics, the KKV bus can use different (high impulse) propulsion to provide the necessary total $\Delta V$ required for an intercept.

This does not make a KKV bus a requirement for such high $\Delta V$ missions - a clever war fighter might provide his side with multi-stage missiles in which the first stage had similar high $\Delta V$ capabilities. However, the KKV bus provides a bit more flexibility than simply extending the range of the missiles.

The engagement

In space combat there are certain advantages that go along with different engagement aspect ratios.

General

A very non-exhaustive list:

1. A tail chase favors the attacker because the attacker can always turn inside the defenders turn radius.
2. A tail chase favors the defender because projectile engagements require less $\Delta V$ to hit the enemy (you can leave mines in your opponents path).
3. Head on engagements favor directed energy weapons over projectile (it's difficult for projectile weapons to successfully intercept).

Directed Energy vs. Projectile

The laser ship (directed energy) will try to get close enough to the projectile ship so that their laser can get a kill and so that the targeting light-speed delay is short enough that the laser can hit the other ship before it moves. While the enemy fires missiles, the beam will be tasked with shooting any missile which looks like it is within an effective engagement envelope. Priority will be given to hitting the KKV bus before it launches its payload of missiles. One turret will be acquiring a new target while the other turret is firing. As soon as the current target is destroyed, the beam will switch turrets and the roles will reverse.

The projectile ship (kinetic energy) will try to stay outside of the laser ship's effective range. They'll fire a barrage of KKV buses at the laser ship. They will try to saturate the laser ship's defenses. A laser ship will be able to fire more shots than a projectile ship so the projectile ship needs to complete the defense saturation as quickly as possible. After an engagement the projectile ship will need to restock its inventories.

Weapons Visible to Human Crew

Rather than making the weapons visible (especially at the range of 11 million miles!), what the human crew might be seeing is their defensive computers projection of the enemy's aim point.

Alternatively, if the enemy ship is directly firing projectiles or missiles are approaching you, then your defensive systems will definitely be tracking those objects and providing the human crew with probable trajectories. For projectiles with propulsion, the result will be a 3-dimensional shape representing the incoming ordinances propulsive capabilities (this is sometimes called a basket but it is usually not basket shaped). CJ Cherryh provides an excellent treatment of craft and weapon probable locations based upon latest data, known hardware capabilities, and light speed delays

If the enemy is firing directed energy weapons, you obviously won't see much of the beam unless it hits you, but it is possible that if your sensors are good enough, they could detect the passage of a powerful laser weapon based upon reflections from dust and gas. The computer could provide that feedback to the crew too.

The crew would have up to minutes to respond to the threats.

Summary

Basically, instead of making the weapons visible to a human's naked eye, the combat information system is overlaying all of its information on the map/screen and providing the human crew with information about probable trajectories, laser misses, aim points, etc.

If your enemy is pointing a multi-gigawatt FEL laser at you and their probable aim point is at the bridge, it would give the crew of the ship, the same feeling as if they saw incoming tracer rounds from that same ship.

• And instead of random dust and gas, the ship might be spreading its own sensor dust, either nanotech or larger probes. Using inferometry techniques this sensor cloud can be getting a much better view of the area, and it can report passing beams and sensor nodes destroyed by the beam. – Zan Lynx Apr 1 '16 at 22:16
• What's the advantage of using a single KKV bus to deliver the missiles to within striking distance, as opposed to having each missile be a multistage rocket, with the final stage being the same as the missile the KKV would have delivered? According to the Tsiolkovsky rocket equation, if you want to increase the velocity of a single payload of mass $m$ by an amount $\Delta v$ using a rocket with exhaust velocity $v_e$, the initial mass with fuel would be $m*e^{(\Delta v/v_e)}$. Whereas if you want two rockets with payloads $m/2$ to increase their velocity by the same amount, the total initial – Hypnosifl Apr 2 '16 at 22:38
• mass of both rockets including fuel would be $(m/2)*e^{(\Delta v/v_e)} + (m/2)*e^{(\Delta v/v_e)} = m*e^{(\Delta v/v_e)}$, same as in the previous case where both payloads were carried by a single larger rocket. So I don't see any fuel advantage to carrying all the missiles in one vehicle, and it also has the disadvantage of making it easier for your enemy to destroy all your missiles with one well-aimed shot before the vehicle gets close enough to launch them, whereas if the missiles form a spread-out swarm to begin with it's harder to stop them all. Why put all your missiles in one basket? – Hypnosifl Apr 2 '16 at 22:40
• My position is that either approach will work. I think the KKV bus provides more capability & flexibility. Might make for an interesting treatment in the fiction though if one side uses one approach and the other side uses the other. – Jim2B Apr 5 '16 at 0:59
• You're most welcome. I highly recommend that everyone interested in this site also read that Atomic Rockets site. It's amazing! – Jim2B Apr 15 '16 at 13:40

As you mentionned, after shooting any projectile you will have to get a recoil. To avoid that you could have your projectiles accelerate by themselves (like rockets). A shot would consist in releasing the projectile and waiting for it to accelerate toward its target, which could take a few seconds and give to the pilot some time to avoid the shot if his ship is nimble enough. Due to the increasing speed of the projectile it would be difficult to anticipate all the parameters and shoot a target at an unusual range.

This system could work for any kind of projectile, as long as you can make rocket thrusters of the right size.

• To avoid problems with recoil you can also have a gun design that shoots some exhaust with equal and opposite momentum out the back at the same time it fires a shot forward. – Hypnosifl Apr 1 '16 at 17:35
• @Hypnosifl I'm imagining some hilarious whiplash if those two systems aren't synced up exactly – Clyde Apr 1 '16 at 19:51
• You've discovered Rocket Mode – Mark Apr 1 '16 at 20:54
• People tend to think of recoil in space as a ways more massive problem than it actually is. Let's say, you have a projectile that weights 0.25Kg (=0.55 pounds) which is a pretty huge shell, and it leaves the cannon with an impressing 2km/s (=4473mph which is 2 times the fastest regular naval cannons). Now, if your ship weights 1500 kg (the approximate weight of the ISS + some thrusters and fuel), the recoil will be 0,33 m/s (=1.2 Km/h or 0.74mph). I think a vehicle which travels by cosmic speeds (km/s magnitude) would barely have a problem with such a recoil. – mg30rg Apr 4 '16 at 8:38
• @mg30rg I dont know what happened, but your numbers are way far off. The ISS has a mass of roughly 420t, and .25kg isnt really that much, a 22mm kinetic missile for a 120mm Sabot already has a mass of over 4kg. For a loong range engagement in space 2km/s is way to slow, I'd expect those kkvs to have a muzzle velocity in excess of 20km/s (the US Navy Railgun already achieved almost 8km/s in atmosphere). For these kinds of energies its not only important to calculate the drift/velocity vector caused by firing the weapon, but also the stress it causes to the weapon mount and ship structure. – Doomed Mind Apr 4 '16 at 22:03

Well, I was with this same question in mind, but I searched for videos about star wars and I found this one: https://www.youtube.com/watch?v=1po2ut5zi0Y

As it says, a "blaster" (real term would be a "Plasma Railgun") could eject an plasma "bubble" to 200 km/s and reach tempetures hotter than the sun. He explains with more details, you should check it out.

• While this is an interesting answer, more of the information from the video should be moved into the body of the answer. Please see this for why answers that are primarily links should be avoided on SE. – Gryphon Feb 4 at 15:50
• I have no clue why you made this post a community wiki, but I am pretty sure this is NOT such – L.Dutch Feb 4 at 16:09
• oh, sorry for the trouble, I just got too excited with the gun concept :T – Neto Ananias Feb 4 at 19:58