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Orbital Fighting [Star wars is a good example]


bulletrhli

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Space Warfare would vary dramatically depending on the technology level of those fighting. As we are depending on chemical guns and missiles, and still using chemical rockets as propulsion means that we are limited to simply shooting down satellites or space stations with aircraft launched missiles.

Leap forward 50 to 100 years and consider these technologies which have a good chance of being available by then.

Cheaper, reusable and more powerful launch systems - This could allow heavier objects, including weaponry to be put into orbit at a fraction of the cost of todays rockets, this could make putting weaponry into space much more feasible.

Better propulsion - Fission rockets and vasmir engines (as well as others) could allow massively more dV than todays rockets which would let satellites and spacecraft more room to manoeuvre.

Denser Power supplies - Current power storage is heavy while still not storing that much energy. In 50 years new ways of storage may have been invented.

Lasers and Railguns - Both types of weaponry are experimental now but may be working in the near future. With better launch systems and power supplies, these could be mounted on satellites, space stations or military spacecraft, alongside missiles with may still be viable. Lasers could more easily be protected against with heat resistant tiles and spinning the spacecraft to allow the heat to radiate. Railguns could be dodged but couldn't be armoured against and missiles could be shot down with lasers and point defence, meaning combined arms would be needed.

However there isn't any reason to fight over space so even with the technology around, it is unlikely it will ever be used in this way.

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Interesting...

I'm sure there was a thread around here somewhere about the feasibility of kinetic weapons. See this thing below...

[table=width: 500, class: grid]

[tr]

[td][/td]

[td]Kinetic Energy (J)[/td]

[td]Velocity (m/s)[/td]

[td]Mass (Kg)[/td]

[/tr]

[tr]

[td]Halo Super MAC[/td]

[td]2.16E+20[/td]

[td]12000000[/td]

[td]3000000[/td]

[/tr]

[tr]

[td]Halo Frigate MAC[/td]

[td]2.7E+14[/td]

[td]30000[/td]

[td]600000[/td]

[/tr]

[tr]

[td]Mass Effect Mass Accelerators[/td]

[td]1.62006E+14[/td]

[td]4025000[/td]

[td]20[/td]

[/tr]

[/table]

Those values are for the projectiles. But this just says it perfectly.

Well, first off why should they have to? So long as they're sturdy enough to survive the recoil without getting torn apart, a momentum change is just a course change. No big deal really.

But, math. Let us take a UNSC frigate as an example. I don't think they're given a mass anywhere, but they are given some dimensions on the halo fan wiki. The smallest is the Stalwart class, at 478m by 152m by 112m. If I had a model of one handy I could get the true volume, but I don't so I'm just going to eyeball it as a block coefficient of .3, so that is 2.4 million cubic meters of volume.

Material is hard too. My instinct is to assume they're about as dense as a modern naval vessel, but I don't really know that number either. But I know a naval vessel can't be more dense than water, while a space ship doesn't have that restriction. So water might actually be a decent ballpark, and it's neat. 2.4 billion kilograms.

The standard MAC is described as firing a 600 ton slug at 30,000 m/s. Force = mass*acceleration, so it's pretty easy to get our force out of this. 18 billion newtons, though it depends on what ton you use(I hate tons for this reason.). Dividing that by our previously arrived at mass.... gets us an acceleration of 7.5 meters per second. Which is fairly piddling as these things go.

Of course the mass estimate of the frigate could be way off, but probably is good enough to get a rough idea of scale.

To the first, yes that's definitely true. That's why I pointed out that to fusion powered space warships other options might be available, such as the free electron laser Rune mentioned.

To the later, that is true, but the MACs were originally built before the covenant showed up with their highly accurate slipspace jumps, and are frequently used at long range in closing engagements.

I've also spoken with engineers who work in related fields who've told me that the powers and switching times for c-fractional coil guns might actually be physically impossible. The ease of building personal scale hand made weapons says nearly nothing about their applicability to space combat.

And...

Lets put some science into Halo. Unfortunately, Halo did never run on science.

So we have this so-called super-MACs, propelling a 3000 ton projectile at .04c. We know that the kinetic energy of a mass is E=1/2*3000kg*(11,991,698.32m/s)²=1/2(6000kg*143,800,828,597,890.8224m²/s²) = 2.16*10^17 J. Now we remember that there are 300 of these in orbit. This puts a full salvo of all 300 super MACs at 6.5*10^19 J. To put this in reference, the energy output of the Sun is estimated at around 3.85*10^26 watts or J/s, and the global energy consumption in 2008 were about 143.9 pWh, or 143,900,000,000,000 kWh or 518,040,000,000,000,000 kJ or 518,040,000,000,000,000,000 respectively 5.184*10^20 J. This means every salvo of the EDG equals about 1/8 of the annual global energy consumption. And no, it is never explained where all this power comes from, although you will need a massive network of fusion power plants to keep such a system running. At least it suggests that Halo-humanity is a very solid type 1 on the good old Kardashev scale. I hope you see why the coilguns Halo uses are horrible weapons.

But according to Newton every action triggers a reaction, so according to conservation of momentum the same amount of energy pushes the MAC "backwards". To calculate the resulting delta v we would need the mass of the station ... which we sadly do not have. What we do have, however, is the mass of UNSC warships and the MAC rounds they fire (although it is implied that super-MACs are relatively lightweight). A Marathon-class heavy cruiser has a mass of 100,000 tons (yes, a kilometer-long scifi-warship is lighter than WW2 battleships. :huh:) and fires 600 ton slugs. This would put the mass of a orbital defense station at about 500,000 tons. Now it is a simply matter of rearranging the equation from the beginning.

v²=1/2m/E

v=sqrt(1/2m/e)

v²=(1/2*500,000)/216,000,000,000,000,000=1.157*10^-12

v=sqrt(1.157*10^-12)=1.075*10^-6

This is ... disappointingly low. Probably my math is wrong somewhere. I totally want this things to be violently deorbitted/escaping Earths SOI. ;.;

Edited by blackout11c
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Hey, what about that burst of high-energy Hawking radiation warpships are supposed to emit when they drop the bubble? That would be a heck of a weapon, frying everything in front of starship literally the moment it drops out of FTL.

This is dramatically reduced with modern warp methods. Think about it this way, all that energy being released has to be put in there first. Where in the world would you get that much energy from? So fortunately or unfortunately, depending on your point of view, a realistic warp ship would emit a fairly modest amount of radiation.

But according to Newton every action triggers a reaction, so according to conservation of momentum the same amount of energy pushes the MAC "backwards". To calculate the resulting delta v we would need the mass of the station ... which we sadly do not have. What we do have, however, is the mass of UNSC warships and the MAC rounds they fire (although it is implied that super-MACs are relatively lightweight). A Marathon-class heavy cruiser has a mass of 100,000 tons (yes, a kilometer-long scifi-warship is lighter than WW2 battleships. ) and fires 600 ton slugs. This would put the mass of a orbital defense station at about 500,000 tons. Now it is a simply matter of rearranging the equation from the beginning.

Gah. This guy hurt my brain. Momentum conservation means that the same amount of momentum goes into recoil. 0.04c to a 600T slug against a 100kT ship gives 72km/s of recoil.

Edited by K^2
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Halo is really not going to be the best thing to take accurate measurements from. :P Modern rail guns fire a 3.2kg slug at around 2.4km/s. So that's the best numbers we've got to go by. :) Assume you're firing that from something the size of the space shuttle...

Now anyone want to do the maths for me because I've forgotten how to do even basic physics lol.

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As i found here: http://cs.wikipedia.org/wiki/Space_Shuttle (dont even try to read it it is not in english. find a english version, i hope they are not different) shuttle veights around 115 tonnes.

So shuttle firing 3,2kg projectile at muzzle velocity 2400 m/s would change its velocity approximately by 0,0668 m/s. But thats a willd gues based on formula that i barely remember.

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Assuming the above calculation is correct then the recoil would be easily manageable and the weight of the gun would probably be lift able to orbit, especially if the vehicle was specially designed to have such a weapon built in. With computer targeting this could take out satellites with ease and be able to fire numerous shots.

Missiles would be even easier to transport to orbit and could be fired to intercept satellites in almost any other orbit.

With current or near future technologies kinetic weapons will be very feasible in space.

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Sounds like alot of effort to put a big ol' mac cannon into orbit along with several thousand metric tons of ammunition. I will let my enemies build those whilst i have swarms of smaller, lighter, easier to move vessels that are to small for that giant mac to do anything against.

The only usefull thing you could have above a planet is some sort of orbit to surface weapon to take out strategic targets on the ground. Now if we use an orbital missile platform then you have pretty much wasted a bunch of money as its nothing a surface deployed missile cannot do. If you have an orbital kinectic style weapon (such as the halo mass accelerators) then its gonna be huge, need alot of power and be easy to throw surface-orbit missiles at.

I Still hold there will be no actual ship-ship combat. Ship-ship combat is something for a seafaring navy. There is nothing worth fighting over in space so nations will have no need for weaponised vessels up there

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The only usefull thing you could have above a planet is some sort of orbit to surface weapon to take out strategic targets on the ground. Now if we use an orbital missile platform then you have pretty much wasted a bunch of money as its nothing a surface deployed missile cannot do. If you have an orbital kinectic style weapon (such as the halo mass accelerators) then its gonna be huge, need alot of power and be easy to throw surface-orbit missiles at.

I Still hold there will be no actual ship-ship combat. Ship-ship combat is something for a seafaring navy. There is nothing worth fighting over in space so nations will have no need for weaponised vessels up there

I agree that there is unlikely to be any ship to ship combat in space thank god. The Kessler syndrome would ruin earth orbit for hundreds of years.

However in theory putting a mass accelerator or rail gun into orbit would be easy as modern prototypes weigh less than 20 tons. (that's a guestimate) Then again a Anti Satellite missile could just shoot it down. :P

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I agree that there is unlikely to be any ship to ship combat in space thank god. The Kessler syndrome would ruin earth orbit for hundreds of years.

However in theory putting a mass accelerator or rail gun into orbit would be easy as modern prototypes weigh less than 20 tons. (that's a guestimate) Then again a Anti Satellite missile could just shoot it down. :P

But! Modern prototypes are to be fired from the surface (as i understand at the moment) If you fire a current prototype from space how far would it get befor re-entry and terminal velocity starts to have an effect? I reckon they would be heavy ass things that are next to useless other than releasing some sort of biotoxin into the atmosphere. Dont forget the immense power requirements. Solar panels aint gonna cut it (unless that 20 tons includes the power source)

Edit: I just remembered you could add an explosive payload to a slug, duuhh. I still think they would be difficult to use in space.

As you mention the kessler syndrome i came up with a theory earlier too. Lets say a hostile alien race invades. A simple defense would be to deliberatley make a kessler syndrome. send a bunch of fragmentation rockets into the sky and creat a layer of untraversable death debris. Alien invaders will have to wait for a few centuries :D This is assuming aliens dont have any sci fi tech and still adhere to what we know about physics. They would primarily be full of ground forces and orbit to atmosphere craft maybe?

Edited by vetrox
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If you have an orbital kinectic style weapon (such as the halo mass accelerators) then its gonna be huge, need alot of power and be easy to throw surface-orbit missiles at.

There's no reason a kinetic weapon would need to be large or electrically powered. Chemical propellant would work just as well in orbit as it does on the ground, in fact the high energy density of chemical propellants are even more valuable when weight is so expensive. The only weapon ever sent into space on a spacecraft that we know of was an ordinary autocannon. If you wanted something with a bit more smash an autoloading tank or naval gun would be more than sufficient to take apart quite large space vehicles, and would represent a lot of stowed kills in a fairly light and compact package. Something like Oerlikon's 35mm revolver firing smart fuzed rounds weighs about 3 tons with enough ammunition for dozens (potentially hundreds) of engagements and is designed to take apart aircraft and missiles, which are constructed the same way as spacecraft. If you wanted to hurt a tougher target an autoloading 105mm L7 tank gun and a dozen rounds would weigh about the same.

Edited by Seret
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There's no reason a kinetic weapon would need to be large or electrically powered. Chemical propellant would work just as well in orbit as it does on the ground, in fact the high energy density of chemical propellants are even more valuable when weight is so expensive. The only weapon ever sent into space on a spacecraft that we know of was an ordinary autocannon. If you wanted something with a bit more smash an autoloading tank or naval gun would be more than sufficient to take apart quite large space vehicles, and would represent a lot of stowed kills in a fairly light and compact package. Something like Oerlikon's 35mm revolver firing smart fuzed rounds weighs about 3 tons with enough ammunition for dozens (potentially hundreds) of engagements and is designed to take apart aircraft and missiles, which are constructed the same way as spacecraft. If you wanted to hurt a tougher target an autoloading 105mm L7 tank gun and a dozen rounds would weigh about the same.

In my mind they are not for taking out space vehicles. They are for engaging ground targets. And i say power just because a magnetic accelerator requires alot of power to charge the magnets to launch the projectile.

Small weapons such as your examples will probably be next to useless at destroying ground bases

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In my mind they are not for taking out space vehicles. They are for engaging ground targets. And i say power just because a magnetic accelerator requires alot of power to charge the magnets to launch the projectile.

Small weapons such as your examples will probably be next to useless at destroying ground bases

I was talking about engaging space vehicles yes. Plenty of strategic value in shooting down the other guy's nav and recce sats.

For attacking ground targets you'd just use smart bombs. If you're shooting at ground targets you don't need to add any kinetic energy, the weapon already has bags of gravitational potential energy that it can trade into kinetic energy. Essentially the power for the weapon was the fuel you burned to get it into orbit. You'd only need a small separating charge to ensure positive separation and get it onto a re-entry trajectory.

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Actually stealth in space is really hard, particularly if you have enough hardware to put something serious into deep space. Asteroids are hard to spot because we're not really investing much in looking for them and because they're only a couple of degrees above ambient temperature. A nuclear reactor is a lot hotter than an asteroid and much easier to spot in infrared

But you have the big advantage that you *know* from where the enemy is looking. It shouldn't take that much effirt to build a heat shield on the exposed side and a radiator on the dark side that dumps excess heat. Since the surfaces radiating heat are not visible from earth (or whatever planet you're attacking).

You can then setup base on the far side of the moon (either on the surface or in an orbit that keeps you locked on the far side) and come all out in a surprise attack.

I do agree with you -- space battle will not look like anything we've seen so far. How it will look exactly? Time will tell.

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But you have the big advantage that you *know* from where the enemy is looking. It shouldn't take that much effirt to build a heat shield on the exposed side and a radiator on the dark side that dumps excess heat. Since the surfaces radiating heat are not visible from earth (or whatever planet you're attacking).

Not that is impossible, but your ship mass will only be radiators. Even if you manage to hide yourself behind a heatshield (which by the way will radiate heat, there is no way it can be perfect), how will you direct your vessel without any trust ? It is impossible to assume that your target will not move for days.

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When we actually have political entities on separate planetary bodies at war, we may have space battles. Until then, why bother when you can just invade their land? Well, I guess it would look cool, and I would like to see what the world superpowers could come up with if they all somehow agreed to make all wars be fought in space.

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When we actually have political entities on separate planetary bodies at war, we may have space battles. Until then, why bother when you can just invade their land? Well, I guess it would look cool, and I would like to see what the world superpowers could come up with if they all somehow agreed to make all wars be fought in space.

What, you've never heard the expression "Nuke 'em from orbit, it's the only way to be sure" ??? There will be battles in space, because control of space conveys *HUGE* advantages in C4ISR and early strikes. Which is to say, if you try to launch an invasion without at least denying space (and air!) to your opponent, your invasion forces will get zapped before they can leave your own soil!

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Back to the original topic, which I think of specifically as "orbital dogfighting"... is it really infeasible?

Suppose there is a very valuable target in orbit that you want to capture but not destroy... say a construction facility or something. You would want to rendesvouz with the target, and the target will either want to avoid you or engage you. Suppose the target cannot avoid, then it has no choice but to engage. Wouldn't that give rise to the possibility of dogfighting? Perhaps as a method to execute precision strikes or to shoot down boarding shuttles that are hard to hit by the station's main weapons?

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Back to the original topic, which I think of specifically as "orbital dogfighting"... is it really infeasible?

Suppose there is a very valuable target in orbit that you want to capture but not destroy... say a construction facility or something. You would want to rendesvouz with the target, and the target will either want to avoid you or engage you. Suppose the target cannot avoid, then it has no choice but to engage. Wouldn't that give rise to the possibility of dogfighting? Perhaps as a method to execute precision strikes or to shoot down boarding shuttles that are hard to hit by the station's main weapons?

Not really feasonable. If you see an enemy fleet, well just bring out some flak cannons, and voila! Scrap metal, neatly arranged so your orbital refineries can process it... Once we actually have fast maneuvers (remember that it takes ~a week to land from the ISS in a Soyuz, at least, because of all the planning, training, testing, etc. that goes into the maneuver. War needs split-second actions. You would need some really expensive ships, which would probably cost more than whatever land/assets/leverage you wanted that got you into the war in the first place.

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Not that is impossible, but your ship mass will only be radiators. Even if you manage to hide yourself behind a heatshield (which by the way will radiate heat, there is no way it can be perfect), how will you direct your vessel without any trust ? It is impossible to assume that your target will not move for days.

As I mentioned before, the radiators are behind the heat shield. There's no reason the radiators wouldn't be radiating the heat from the heatshield as well.

Who said you can't use thrusters? Even if you can't mask the heat from the thruster you wouldn't need to fire thrusters continuously.

The target is a planet. You know how it moves. If your opponent can move it in random ways you'll have bigger things to worry about. The goal is not to land on the national mall in complete stealth and perform a five column parade. The goal is to get close enough to stage an attack where the opponent doesn't have time to prepare proper defense at the right spot.

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And if your enemy has sensor platforms in deep space? Also, how do you plan to hide thruster firings?

That would be the logical next step. How many do you need? Space's big. Are you going to position them only in the equatorial plane? Where do you point them at?

The weapons and craft are different, but I doubt space battles will be like WW1 dogfits. I think they'll be much more like the battle for the atlantic in WW2. Stealth, detection, and encounters are short, fierce and will nearly always end in destruction of one of the participants.

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Once we actually have fast maneuvers (remember that it takes ~a week to land from the ISS in a Soyuz, at least, because of all the planning, training, testing, etc. that goes into the maneuver. War needs split-second actions. You would need some really expensive ships, which would probably cost more than whatever land/assets/leverage you wanted that got you into the war in the first place.

That's because of the safety margins. Military operations allow for a much higher risk factor. And if you throw landing into a fully automatic mode, a computer can plot a course and land a ship within at most a revolution from the target, or about 90 minutes. It can also plot intercepts that are very hard to counter. Point is, if you actually get into close combat situation, things can be interesting.

Problem is getting close. If anything you might have to worry about would have to approach on similar orbit, you'll have many hours of advanced warning.

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As I mentioned before, the radiators are behind the heat shield. There's no reason the radiators wouldn't be radiating the heat from the heatshield as well.

Your heatshield will have the same temperature as the rest of your ship. The only reason it could be cooler than your ship is an active cooling system.

An active cooling system will consume an awfull lot of energy, therefore you need a electric generator system.

Electric production produce heat too, therefore your will have an enormous quantity of heat to radiate.

If you want to radiate heat on the opposite direction of your heatshield it will cause a problem : big radiators are required. They will be so big that your ship will probably be big enough to be spotted on a classical radar.

On the problem of thrust. It is not needed to thrust continuously to be spotted. Even a very small thrust can be spotted at very large distance. And you will have to do an insertion burn, which will never be a small burn.

And that is assuming you have plan your trajectory way before entering the planetary system your target is in. But stealth is a combination of low detection chances and speed. If you are coasting in the direction of a planet, coming from another planet or another planetary system it will take months before you are at firing range. As time goes by, your chances to stay hidden are dropping (you will pass in front of a star with your gigantic-radiator-over-equipped ship for instance).

An other issue is that to fire you will have to turn on your active sensor, revealing your position. And an orbital ship is far more vulnerable than a ground-based weapons system.

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That would be the logical next step. How many do you need? Space's big. Are you going to position them only in the equatorial plane? Where do you point them at?

How tight a cone are you confining your emissions to?

The weapons and craft are different, but I doubt space battles will be like WW1 dogfits. I think they'll be much more like the battle for the atlantic in WW2. Stealth, detection, and encounters are short, fierce and will nearly always end in destruction of one of the participants.

Every course change requires emitting a cloud of hot gas. If the enemy observe the actual firing, they can tell exactly how massive you are and what your trajectory is.

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