Sci-Fi Idea

[Machine Ghost]

I think this is the right place for this thread, but if I'm wrong tell me.

Basically I have wanted to write a serious, hard-science space combat story. I have fully read the Atomic Rocket Site at least twice, and thought up the idea while reading the Space War section.

It seemed, to me that fighting in space was pretty much just lining up to be shot; there is no where to hide, and its hard to miss (a very major simplification, I know). So, I thought that it sounded an awful lot like Napoleonic line combat, and that how the idea got started.

Overall Tech and Enviroment:
Thrusters are fairly weak, so Hohmann Transfer Orbits are all used, just a little bit faster than today. Ships and ship parts are pretty cheap, so countries can afford a lot of them, freelance merchants are fairly common.
There are full colonies on Mars, the Moon, Asteroid belts. (all with population growth).

The basic combat ship:
Maybe 100-200 feet long. (from back to front) Atomic engine and propellant, storage (for food, air, water, etc), very small crew quarters (think a Apollo capsule with some capsule hotel rooms stuck to it), large capacitors, very big gun.

The craft would also have maneuvering thrusters (3-4) attached to booms that extended out from the center of mass.

For weapons the main gun would be either a railgun, coil gun, laser, or maybe a missile/drone launcher. Luckier ships will get a handful of CIWS, probably lasers. As for passive defenses, the ships will have whipple shields.

There would be 3-4 crew for each one, pilot/gunner, comm/sensor, engineer. Cooking just doesn't happen, and if you ship gets hit at all, pretty much everyone is dead, so minimal medical supplies.

Combat:
Because all ships have to use transfer orbits, or take a long time to show up, the enemy will know where your going, and how you will get there with a reasonable degree of accuracy. Battles will take place usually where the defenders want to intercept the attackers, usually near-ish to a planet or planetoid.

The two sides will fight like a school of fish armed with automatic weapons. They will speed towards each other, and fairly close to effective range they will split up into battle formations, trying to get side shots (larger target) without exposing themselves to similar fire. Once inside effective range they will open up, fire rates will be slow (maybe 1 shot ever 2-3 seconds), so volleys might be used. Each formation will probably have a command ship, bravely hiding inside a swarm of his friends, this ship will manages the formation shape, cross-formation communication, and other command duties.

After the initial pass, the two sides will probably have to stop and turn around for a second pass, if both sides still want to fight. Or the surviving attacker can speed on to his objective while the defender tries to catch up. This means the defender is actually at a disadvantage because he will have to hold ships in reserve to pick off survivors.

If they are fighting in orbit, that adds a whole new dimension, which I haven't completely thought of yet, but will get to later.

Any suggestions?

[Junghalli]

I think missiles might be a better weapons system than guns. Railguns and lasers are likely to be big, heavy, require massive cooling and power systems etc., all of which are bad on a realistic spacecraft where saving weight will be a massive priority. Lasers are especially bad, since they're very inefficient. They'll also likely involve delicate complex and expensive components. By contrast, missiles are reliable tried and true technology: all you really need is something like a modern ICBM. They'll probably be longer range than guns too, because they're guided (unlike railguns) and don't have to deal with diffusion (unlike lasers). Lasers and guns are probably better for CIWS. Victory in a missile exchange would go to the side that either has better CIWS or can throw more missiles at the enemy.

Now some generals:

Spacecraft will be engineered like aircraft. Every extra kg of mass translates into more fuel, so the lighter the better. You seem to have this aspect of it down pretty well.

One of the biggest advantages a space warship can have is a good engine. There's no stealth in space, so there's no hiding your moves. The advantage will go to the side with the better engines, who can shape the battlefield to their advantage. Fights will typically consistent of hours, days, or weeks of manuevers followed by a few seconds or minutes of actual combat, quickly decided.

[Machine Ghost]

Missiles are more accurate, but they are larger and slower than other weapons. In the volume and mass for one missile, or one guided coilgun round, you could fit quite a few small, metallic darts or maybe an extra capacitor. Also I figured that laser and capacitor technology would have matured to be more effective.

Now that I think about it, ICBM-like missiles could be an alternative to ships with crew, cheaper and simpler, except they aren't smart enough to handle a changing battlefield. So they would be used to precede a fleet or for harassment attacks. To continue the Napoleonic land combat metaphor, they are like cavalry and artillery mixed together.

[Darth Raptor]

Use lasers for point defense, not ship-to-ship weapons. You can't really "mature" laser technology to get around the waste heat issue. Any laser powerful enough to carve up an enemy ship is an internal meltdown waiting to happen. I doubt you want your ships venting loads of hot gas after every shot or sporting huge, vulnerable radiator panels.

[Axiomatic]

Remember the bit about there not being stealth in space? That applies to missiles too. I don't think they'd ever be useful, since the distances involved would be big enough for it to be trivially easy to intercept all incoming fire.

Lasers you at least can't see coming, because when you see them, you've been hit.

[Zixinus]

Remember that missiles can counter as well. You can fire more missiles then what the enemy ship's defence system can handle, and once the missiles are close enough, you can simply shoot the warhead to do contact-hit. You can also encase the missile in powerful armour. With shaped nuclear warheads, you may not even have to do that: you simply use the blast. Anyone caught close enough to the blast will suffer massive doses of radiation sickness.

Also, remember that shooting down a missile may not as trivial as you think. Remember this strip:

The situation is a bit similar: the crew has to launch an object on a specific path but the mechanism for ejection is stuck. They have to take schedule and re-plan their flight to fix the problem.

[Darth Wong]

Remember that missiles can counter as well. You can fire more missiles then what the enemy ship's defence system can handle, and once the missiles are close enough, you can simply shoot the warhead to do contact-hit.

If the enemy has powerful lasers for point-defense, it costs him a lot less to shoot down your missiles than it cost you to fire them.

You can also encase the missile in powerful armour.

Thus making it heavier, slower, less maneuverable, and more expensive.

With shaped nuclear warheads, you may not even have to do that: you simply use the blast. Anyone caught close enough to the blast will suffer massive doses of radiation sickness.

Nonsense. Any civilization which has the ability to fire armoured missiles in space should be able to shield the occupants of a spacecraft from X-rays, and there is no fallout concern in space. The inverse square rule means that as long as it doesn't go off right next to you, the damage should be survivable.

Also, remember that shooting down a missile may not as trivial as you think. Remember this strip:

The situation is a bit similar: the crew has to launch an object on a specific path but the mechanism for ejection is stuck. They have to take schedule and re-plan their flight to fix the problem.

I thought we were talking about the kind of sci-fi civilization whose ships can fire swarms of armoured missiles.

[Zixinus]

I thought we were talking about the kind of sci-fi civilization whose ships can fire swarms of armoured missiles.

The point with the comic was nothing with the missiles: it was to point out that problems that seem easily solvable in space can turn to be very much complicated then initially thought, due to the uniqueness of zero-gravity (this works the other way around as well). In this case, the spaceship/spaceplane (don't know what to call the Flying Chicken) has to change its tight schedule due to a minor mechanical error that would be otherwise quickly fixed in an another environment. Have you heard of a boat that had to stop because it couldn't throw something overboard?

What I'm trying to say, is that something that looks fairly trivial from theory can be a big technical challenge in reality, and this is especially true when it comes to astronautical engineering, as it is such a different environment.

If the enemy has powerful lasers for point-defense, it costs him a lot less to shoot down your missiles than it cost you to fire them.

True. On the other hand, if one missile slips trough the defences then it will cost the enemy several times more, while a laser blast can be survived with much less armour then what would be required to survive a nuclear blast (which I doubt one can).

Whether to use missiles or lasers very much depends on what tech assumptions you are going on and how mature lasers are.

Nonsense. Any civilization which has the ability to fire armoured missiles in space should be able to shield the occupants of a spacecraft from X-rays, and there is no fallout concern in space.

True, but with what assumptions? And would the extra shielding be worth all the extra mass to tow around, which is especially important when you use relatively weak rocket engine (when is it appropriate to say "rocket motor" and when is it to say "rocket engine"?).

If you can lug around that much shielding, then sure the idea is worthless. Then you just have to make your regular contact-hit and blast the spaceship to pieces your regular way. However, the trade-off is that with this tactic, there is less chance of the enemy being missed or that the enemy can "dodge" by maneuvering with full burn (as likely that will work).

Another thing. I said x-rays. Now that I think about it, shouldn't it be gamma rays? Or do both happen?

Thus making it heavier, slower, less maneuverable, and more expensive.

Of course. Did I imply the opposite? A higher chance of survival can also very well worth that extra cost and trade-off. I am quite certain that nuclear warheads are not cheap to begin with.

[Adrian Laguna]

Remember that missiles can counter as well. You can fire more missiles then what the enemy ship's defence system can handle, and once the missiles are close enough, you can simply shoot the warhead to do contact-hit.

If the enemy has powerful lasers for point-defense, it costs him a lot less to shoot down your missiles than it cost you to fire them.

That depends on what you mean by "cost". The limiting factors of lasers are power, heat, and range. The only limiting factor of missiles is how many you can carry. Missiles can always be fired from farther away than lasers can hit back reliably, but lasers can always hit missiles before they get close enough to inflict damage. The viability of missiles is dependent on whether the number of missiles a ship or fleet can fire is sufficiently higher than the number of missiles that the enemy ship can shoot down before their lasers melt or the wave arrives.

Oh, and btw, Zixinus's idea about armouring missiles is retarded. Getting more ordnance is far more efficient than trying to make it survive point-defense.

The inverse square rule means that as long as it doesn't go off right next to you, the damage should be survivable.

I've got three words for you: nuclear-pumped laser.

[Ted C]

Thoughts:

I disagree with Junghalli; stealth should be valuable in space. If you minimize your emissions and the potential returns from active radar, it will be harder for the enemy to detect and target your ship.

Given the amount of advanced warning you've predicted, it shouldn't be too hard for the defender to plan an intercept with a favorable velocity; there's no reason for them to have to "stop and turn around" as you put it, they would seek to engage under the best conditions for them. Again, detecting and tracking the opposition is going to be important: if you have the wrong velocity, you will have little opportunity to fire.

I see no reason why beam weapons would have a serious heat problem; you'd simply want to have heat radiators exposed to space. It would have limits, of course, but there's no reason they wouldn't work better than things like rail guns, which would have far more effect on your ship's velocity. Laser beams will also get to the target at lightspeed and will be impossible to "shoot down".

Missiles will be useful primarily for their ability to track and home on a target. They'll have a higher cost-per-shot that lasers, but the ability to put a nuclear warhead on it will make it easy to have a very powerful missile.

I would question the value of asteroid-based stationary defenses. Seems like it would be very easy to just stay out of their effective range.

[Axiomatic]

Actually, range IS a problem for missiles. It's not a problem in that the missile will never reach the target, but there does come a time where it just doesn't make sense to shoot a missile which will end up where the enemy was an hour ago.

[Ted C]

The problem is minimizing your emissions enough for this to work is impossible. An operating ship is going to generate heat. It can either hold on to that heat forever and destroy itself (well, it can't actually do this perfectly, but it can try to get close) or it can radiate that heat.

This radiated heat will stand out against the pretty empty background of space: 290 K (about room temperature) is a lot higher than 3 K (about space background). Operating equipment would probably run hotter.

I can see where the ship can't have zero emissions, but a ship is still a speck if the vastness of space. It could be mistaken for a star, asteroid, or something else if it's not excessively hot. It might be more effective if you can deploy decoy drones to spoof passive IR sensors.

I don't think nuclear warheads are necessary at all in ship to ship space combat. If a WW2 era battleship shell connects with a space warship, it is probably in pretty bad trouble. Chemical warheads, or just plain kinetic energy in the shot, will probably be enough, and far cheaper, if you use missiles at all.

True enough; a nuke is probably overkill for ship-to-ship combat. Might be effective against large, fixed targets, though, like a space station mounted on/in an asteroid, assuming it can get there without being shot down. Again, decoys might help the missile get past missile defenses.

If the target is inside that range, you don't really have that choice. You can sit far outside and lob missiles at it, but the fortress can shoot them down when they do come inside range.

If you want to pound your target with laser fire, you are almost certainly going to be inside the asteroid's laser range as well. Given that the stationary weapon can be far larger than a mobile one, the fortress' effective beam range should be superior to any ship's beam range. Probably at least on the order of light seconds.

Actually, pounding a space station or asteroid with laser fire should be pretty easy. Since it's movement is relatively predictable, attackers can fire from ridiculous ranges (several light seconds, I would think, if the targeting technology is accurate enough). Laser beams won't lose potency travelling through space the way they do in atmosphere, and it will be relatively hard for the station to target a maneuvering ship.

[Vanas]

Actually, pounding a space station or asteroid with laser fire should be pretty easy. Since it's movement is relatively predictable, attackers can fire from ridiculous ranges (several light seconds, I would think, if the targeting technology is accurate enough). Laser beams won't lose potency travelling through space the way they do in atmosphere, and it will be relatively hard for the station to target a maneuvering ship.

I'm sure one of the physics guys can clarify this, but your laser beam will lose potency over a distance, due to the beam spreading out. You'd be better off with a mass-driver/railgun/whatever the cool kids call it these days.

Or some kind of super-laser.

[Darth Raptor]

Ted C, please read this page before you continue the tired stealth tangent. The short of it: Your ship is going to be ludicrously conspicuous against the cold background of space. To get cold enough to blend in, you'd have to actively refrigerate and, naturally, that requires power and gives off heat, getting you nowhere.

Decoys are also worthless because for them to be at all convincing, they pretty much have to be an unarmed and uncrewed duplicate of your warship. At that point, why not build another ship?

[Adrian Laguna]

I see no reason why beam weapons would have a serious heat problem; you'd simply want to have heat radiators exposed to space.

Radiators are ridiculously easy to shoot-off, as they can't be armoured. It's a liability even if most space combat is one hit = dead ship. Namely, a nuclear weapon which would have only scorched the paint off other ships could mission-kill a ship with its radiators deployed.

Actually, range IS a problem for missiles. It's not a problem in that the missile will never reach the target, but there does come a time where it just doesn't make sense to shoot a missile which will end up where the enemy was an hour ago.

I meant in comparison to other weapons. It is possible to have a technology base that results in beam weapons having greater range than missile weapons, but it is not common.

[Machine Ghost]

As far as nukes are concerned. Fissile materials are not exactly common, and although the US and Russia have managed to stockpile huge quantities in the past, nations on Mars or the Asteroids would not be able to afford them, unless they can get the materials from Earth, which Earth would probably not do. Also nuke are effective against larger ships, but against most, a chunk of metal moving at around 3 km/s will do in most circumstance.

Two things about space battle that can throw you a curve: 1) stationary defences. If someone is attacking you, would you send your own fragile ships to stop him, or let him walk right into the heavily armed, hollowed out asteroid you keep in orbit, and watch as its large laser array (using the huge mass of the asteroid as a heat sink) shreds them to pieces?

I believe the problems with stationary defenses are obvious, they can be hit from across the solar system. Also the defenses might be stationary but the paths for arriving at the target are not. The further a defense is from whatever it is protecting the more chances the attackers can slip around. Move the defenses closer, and the attackers might be able to complete their objective still, if it's something like bombardment, troop landings, or destroying a vital ship. The fighting ships keep the defenses busy, while the other ships do what they have too.

You could stick engines onto these defenses, but then they are not stationary defenses anymore. Larger, slower defense ships are a possibility. But just having a fighting ship pack loiter around where they need to be is just as effective. If you really want too, a asteroid can be towed in to serve as a shield/heat sink.

And 2) Remote control ships. Knowing that you are both walking right into almost certain death and space combat is likely to be pretty predictable on the individual ship scale, why would you waste people on this? Instead, I would expect perhaps a couple command ships and a fleet of automated vessels. These automated vessels would either be laser cruisers or missile carriers - basically the sacrificial first stage of a long range attack.

Might work for defensive purposes, but communication delays make them useless on the attack. To attack it is better to spread your forces out, and minor delays to communication could cost you a ship. Having crewmen on each ship allows for a ship to respond to changing battlefield conditions. Unless you can invent some form of quantum comm-device, of course.

Ted C wrote:
I see no reason why beam weapons would have a serious heat problem; you'd simply want to have heat radiators exposed to space.

Radiators are ridiculously easy to shoot-off, as they can't be armoured. It's a liability even if most space combat is one hit = dead ship. Namely, a nuclear weapon which would have only scorched the paint off other ships could mission-kill a ship with its radiators deployed.

This all makes sense, but I figured that laser armed ships would hide at the center of a formation and pop out for longer range shots.

More Thoughts:

The more I look at it, the more it seems like spacewar will be governed by hit-and-run. One or two hit will cripple a ship, so not getting hit is a must. But it this idea, I thought that rather and avoid shots, running them over with numbers would be more effective.

[Junghalli]

I disagree with Junghalli; stealth should be valuable in space. If you minimize your emissions and the potential returns from active radar, it will be harder for the enemy to detect and target your ship.

If you're using a manned ship it'll probably need to have a several hundred degree temperature difference between itself and its environment just to keep the crew from freezing to death. And, of course, even if you could somehow get around this anytime you fire your engines in the same solar system as an enemy facility you'll be detected. There basically is no stealth in space.

On missiles vs. laser CIWS: you have to remember that lasers have huge cooling issues. I doubt a laser capable of destroying missiles from dozens or hundreds of kilometers away is going to be exactly rapid-fire; cool-down time is likely to be a serious limitation.

[Ariphaos]

I'm sure one of the physics guys can clarify this, but your laser beam will lose potency over a distance, due to the beam spreading out. You'd be better off with a mass-driver/railgun/whatever the cool kids call it these days.

A xaser can get ridiculous - .01 nm wavelength, 22 meter lens will have a focus of about one centimeter at a range slightly over one light-minute (typical starting engagement range for my setting though the numbers of course vary). No missile is going to cover that distance in a remotely reasonable amount of time.

Significantly longer ranges suffer extreme light-delay problems - slight random motion is enough to pull even large space stations completely off course at a light-hour. The only feasible targets at such ranges are planets and megastructures.

At a light minute, though, you're running up against the limits of realism for random motion to be sufficient, and lasers can indeed cover that range.

[Junghalli]

Actually, range IS a problem for missiles. It's not a problem in that the missile will never reach the target, but there does come a time where it just doesn't make sense to shoot a missile which will end up where the enemy was an hour ago.

Well, yes, I meant it'd be less of a problem than with unguided KE weapons.

[Adrian Laguna]

A xaser can get ridiculous - .01 nm wavelength, 22 meter lens will have a focus of about one centimeter at a range slightly over one light-minute (typical starting engagement range for my setting though the numbers of course vary). No missile is going to cover that distance in a remotely reasonable amount of time.

Depending on how much acceleration ships have available, it maybe almost impossible to hit targets at more than a handful light seconds distant. Once engagement ranges become large enough, it's possible to dodge even light. That's where the course correcting feature of missiles can be effective. Again, though, the technology base matters at lot.

[Junghalli]

If you're fighting at light-second ranges you pretty much have to use missiles. Anything else is spray and pray, which doesn't work very well when the distances involved are that huge.

[Machine Ghost]

Even on human crewed ships, I'd imagine most the grunt work would still be done by the computer. The computer would have to analyze the sensor data to determine where the threats are. It would have to actually do the targetting to determine where and when to shoot. It would also probably do the calculations for when to make an engine burn.

While this is mostly true, there are many levels where a computer will not be able to compete with humans. Object recognition is the hardest part, the split second it might take to have a computer sort out data and compile a list of targets, a human will have picked a target (maybe at random), and already fired. It could be done like A Boy and His Tanks (not a too good book, but it has interesting concepts), where a AI handles most of the action, but a human rides along to pick out targets.

Although a human command ship leading a swarm of robotic missiles, ships, and drones might be more feasible. The robots would fight, and the human would plan. Might work, right?[/quote]

[Ariphaos]

Depending on how much acceleration ships have available, it maybe almost impossible to hit targets at more than a handful light seconds distant. Once engagement ranges become large enough, it's possible to dodge even light. That's where the course correcting feature of missiles can be effective. Again, though, the technology base matters at lot.

I have made such calculations before and posted them in previous threads. The equation is:

F = 2A*D^2

A = Average random lateral acceleration (meters/second)
D = Distance (light-seconds)
F = Face (meters) - the minimum diameter you want your object to be in order to safely engage at that range against an opponent with powerful lasers.

For example, at one light-minute, an object with a random lateral acceleration of 1 m/s will be able to accelerate up to 120 m/s during the time between an attacker's sensors are able to note the position of the object and have a laser beam reach it. It will move an average of 60 m/s 'off course' during this time, for 120 seconds, meaning that it covers 7,200 meters during this time.

I have magitech in Solar Storms but the vast majority of the populace has no real access to it, so engagement ranges of a light-meter or so are 'typical', though attacking megastructures and planets complicates this significantly.

[Machine Ghost]

In response to Destructionator XIII:

In Boy and His Tank the person is "jacked" into the tank, so sees through tanks sensors as if it were their own eyes and ears.

The lots of robot ships idea might also help reduce the whole depressing "everyone dies" factor of pre-force field space combat.

[Darth Wong]

I disagree with Junghalli; stealth should be valuable in space. If you minimize your emissions and the potential returns from active radar, it will be harder for the enemy to detect and target your ship.

The problem is minimizing your emissions enough for this to work is impossible. An operating ship is going to generate heat. It can either hold on to that heat forever and destroy itself (well, it can't actually do this perfectly, but it can try to get close) or it can radiate that heat.

Or the heat exchanger could use a canister of working fluid with a high specific heat, which can be jettisoned behind the spacecraft periodically.

This radiated heat will stand out against the pretty empty background of space: 290 K (about room temperature) is a lot higher than 3 K (about space background). Operating equipment would probably run hotter.

So? That only comes into play when you actually fire the thing. It's not a whole lot different than the situation with modern submarines where your position becomes obvious the moment you fire a torpedo.

I don't think nuclear warheads are necessary at all in ship to ship space combat. If a WW2 era battleship shell connects with a space warship, it is probably in pretty bad trouble. Chemical warheads, or just plain kinetic energy in the shot, will probably be enough, and far cheaper, if you use missiles at all.

If the enemy has the ability to snipe you with high-powered lasers, it won't really help you that much to be able to locate him and then fire a chemical rocket in his direction after he fires.

If you want to pound your target with laser fire, you are almost certainly going to be inside the asteroid's laser range as well. Given that the stationary weapon can be far larger than a mobile one, the fortress' effective beam range should be superior to any ship's beam range. Probably at least on the order of light seconds.

However, a stationary target is far more vulnerable to counter-attack than a ship.