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View Full Version : Help me design realistic-ish space combat!



TinFoilHat
2003-Jul-09, 04:12 PM
I run a bi-weekly sci-fi RPG, with an original backstory and universe. I have been trying to maintain reasonably plausible and consistent technology base, introducing as few "magic-tech" devices as possible and exploring the ramifications of those. The recent threads about Enterprise and Stargate military operations have got me thinking about how to model un space combat in my game at least semi-plausibly. I'd particuarily like Stuart's opinion here.

I assume FTL travel similar to that used in Mote In God's Eye, where a "jump drive" can be activated in certain spots in space to take you to certain other spots in space. Travel between worlds is a matter of flying from jump point to jump point at significantly sublight speeds, with only a few minutes spent FTL in jump space. I assume cheap and easy Helium-3 fusion power, and fusion drives with improbably high ISP and thrust-to-weight. Other than that, technology is not significantly advanced beyond current levels - this may seen odd, but it is due to specific cataclysmic events in the universe backstory. No transporters, shields, FTL sensors or FTL communication, or artificial gravity, sensor and targeting capabilities comparable to what we have today, but nearly unlimited delta-V and electrical power available. I have been considering the existence of energy weapons directly powered by fusion reactions - lasers or relativistic plasma beams.

How should space combat work with these assumptions? It seems to me that with no shields, and weapons that include fusion-bomb-tipped missiles, that combat between well-equipped navies would be a short and violent thing. If one good hit cripples or destroys any ship, targetting, sensors, and stealth become pretty damn important, and carriers hanging back from the combat and deploying small, fast missile-ships to attack the opposing fleet becomes the strategy. On the other hand, any decent size ship should carry antimissile lasers, projectile guns, and missiles, as well as ECM, which would imply that ships would have to get close to actually hit each other.

The players in this game won't be directly taking place in any serious battles - they own a small secondhand cargo ship, but will sometimes get caught in the crossfire when larger powers clash.

wedgebert
2003-Jul-09, 04:40 PM
I would take a look the Honor Harrington series or the Night's Dawn series for good looks at how space combat might work.

Honor Harrington uses artificial gravity for propulsion, but you can change that to read He-3 and just lower the acceleration curves (HH has missiles accelerating at thousands of gees, and starships at 400+ gees thanks to artifical gravity).

Night's Dawn uses He-3 (and antimatter to a small, illegal, extent), so it's ranges and accelerations are closer to what you're looking for.

In both books, the stress is on missiles, not direct fire weapons, for both offense and defense. The missiles are basically just large fusion/nuclear bomb pumped laser systems. When detonated, the explosion powers one shot lasers/maser/x-ray lasers that then damage the ship. Since ship combat would most likely take place at hundreds of thousands of kilometers, maybe even millions of kilometers, direct fire weapons would suffer both loss of energy due to range, and the increased possibility of missing due to travel time (which lets ECM have more effect).

In HH, some missiles are not equipped with warheads but are instead ECM and ECCM missiles that are designed to make it easier for the other missiles to hit their targets without being shot down. Other missiles are much smaller and more of an area of effect weapon designed to shoot down incoming missiles.

In Night's Dawn, offensive and defensive missiles (called Combat Wasps) are identical. They are basically drones that are controlled from the launching ship. They can be fired like normal missiles, seeded like mines, or launched and told to say near the ship and act as anti-missile missiles. They come in both bomb-pumped laser and standard nuclear bomb varities.

Either way, the key to victory in both series is acceleration. Absolute velocity means nothing in space combat, it's all about acceleration. If you can out accelerate your opponent, then no matter how fast he is going, you can eventually lose him (as long as you survive until then). Higher acceleration for your missiles means less flight time and increased survivability.

Finally, I want to make a note on your lack of shields, good job :). If you're going to try to be realsitic then you can never add any form of force field technology. There is nothing in our knowledge of physics that would even allow for the kind of shielding found in Star Trek (and similar shows). We'd have to discover a new fundemental force or make some radical new discovery that changes everything before force fields would be possible.

To put it another way, we have plausable theories on how time travel would work, but nothing for force fields.

Colt
2003-Jul-09, 07:23 PM
Just a quick post about weapons: Electromagnetic weapons which throw things could be pretty devastating to a ship. Just punch some holes and let the air escape. Of course you would have to be pretty close to accurately fire these weapons. For instance, in Star Trek, they usually get very close to one another when fighting. A large railgun would work wonders there once the shields were down.

Lasers, lasers would be the most probable form of energy weapon and they have the advantage of getting to their target almost instantaneously, no matter the distance. Another plus to them is that you don't run out of ammunition. They simply keep drawing energy off of the core.

The Man-Kzin Wars are also some good books to read. They make the point that a fusion drive makes a mighty fine weapon. :D -Colt

daver
2003-Jul-09, 08:09 PM
I don't think you should ignore Isp--otherwise things get a bit too silly.

I ran through some numbers; i could pretty easily have made a mistake. Anyway, i get an exhaust velocity of around 2.5%c with 3He + D (the site i found seemed to say that the proton carried 14.7 MeV, the 4He carried 3.7 MeV, with another 18.4 MeV presumably being emitted as gammas. I assumed that the drive plopped those 18.4 MeV onto the 4He nucleus). Someone should go over those; there's lots of room for mistakes. If you assume your missile is half fuel, that gives a total delta V of 1.7% c.

Liquid hydrogen has a specific gravity of .07, liquid helium of .125. However, we're dealing with D and 3He, so the densities need to be changed to .14 and .09, respectively. So, 1 ton of D occupies about 7 cubic meters, 1 ton of 3He about 10 cubic meters. So a 4 ton missile, half fuel, is going to take up about 20 cubic meters.

Obviously, an impact from a two ton missile moving at 1.7% c is going to be fairly significant. The best strategy would probably be to accelerate towards the target, and blow the missile to atoms just before impact. At 100 g's, it would take about about 1.5 hours to hit max speed. That's about 20 million kilometers--on the order of a light minute.

There's not an awful lot you can do to defend against a missile of this sort. Jamming the guidance package comes to mind. Anti-missile missiles are probably your best bet. You're going to have to intercept the missile quite a ways out and maneuver to dodge the fragments. Directed energy weapons seem too short range to be useful.

You mentioned stealth. I think you should forget this, unless you're thinking about relativistic planet busters (well, probably county or state busters). Any accelerating ship will stand out like a beacon.

You'll have to decide if ships coming through the transport point have to be moving at a particular velocity or not. If so, it should be pretty simple to set up forts to defend those.

TinFoilHat
2003-Jul-09, 09:31 PM
You'll have to decide if ships coming through the transport point have to be moving at a particular velocity or not. If so, it should be pretty simple to set up forts to defend those.
Pretty much, ships coming through have to be travelling slowly relative to the jump point. It's not the physics so much as the need to position the ship very precisely before activating the jump drive - activation the drive in the wrong place is lethally bad. So defending systems by guarding the jump points is practical, giving the advantage to the defender in inter-system wars.

The Supreme Canuck
2003-Jul-10, 12:26 AM
First off, please, please, PLEASE remember that lasers are invisible unless thay pass through some form of cloud.

Also, if you have missiles, you don't really need explosives. Just get them up to a very high speed and slam them into a ship. They'd make a big hole, no explosives required. Think of them as huge, guided bullets.

Musashi
2003-Jul-10, 12:56 AM
Modesitt's Ecolitian (or maybe it's the Distant Earth) series has some good space combat. Also, Elizabeth Moon does it pretty well, although she has less of it.

daver
2003-Jul-10, 01:17 AM
First off, please, please, PLEASE remember that lasers are invisible unless thay pass through some form of cloud.

Also, if you have missiles, you don't really need explosives. Just get them up to a very high speed and slam them into a ship. They'd make a big hole, no explosives required. Think of them as huge, guided bullets.

A 1 meter diameter missile going at 1%c makes a 1 meter diameter hole in whatever it hits. If your missile blasts itself into a 100 meter wide cloud of vapor before it hits, it makes a 100 meter wide hole. You want the explosive to increase the cross section of the missile, not to impart damage to the bad guys.

freddo
2003-Jul-10, 01:23 AM
First off, please, please, PLEASE remember that lasers are invisible unless thay pass through some form of cloud.

Also, if you have missiles, you don't really need explosives. Just get them up to a very high speed and slam them into a ship. They'd make a big hole, no explosives required. Think of them as huge, guided bullets.

A 1 meter diameter missile going at 1%c makes a 1 meter diameter hole in whatever it hits. If your missile blasts itself into a 100 meter wide cloud of vapor before it hits, it makes a 100 meter wide hole. You want the explosive to increase the cross section of the missile, not to impart damage to the bad guys.

And you want to do this while conserving as much of the linear momentum you've got going - it's no good if your scatter blast disperses the missle outside the bounds of the target area, or significantly decellerates a large portion of the projectile, you're undoing the whole premise behind the massive acceleration you've been doing.

The Supreme Canuck
2003-Jul-10, 01:23 AM
If you aim it right all you need is a 1 metre hole! But I see the advantages of a bigger one... *Evil Grin*

Musashi
2003-Jul-10, 01:26 AM
Punch the 1 meter hole and then explode.

The Supreme Canuck
2003-Jul-10, 01:35 AM
There you go! Better: puch the hole in something explosive then explode.

daver
2003-Jul-10, 01:38 AM
You'll have to decide if ships coming through the transport point have to be moving at a particular velocity or not. If so, it should be pretty simple to set up forts to defend those.
Pretty much, ships coming through have to be travelling slowly relative to the jump point. It's not the physics so much as the need to position the ship very precisely before activating the jump drive - activation the drive in the wrong place is lethally bad. So defending systems by guarding the jump points is practical, giving the advantage to the defender in inter-system wars.

Defense mechanisms might depend on how big the transfer point is, or what happens to the ship in transit if something is occupying the transfer point. Small transfer points limit the size of ships. Having the transfer either not take place or go fatally wrong if there's an object already at the far side of the transfer makes defending the points trivial. If transfer is a two-way street (contents of the transfer points get swapped) a more active defense is required--maybe something like a Lofstrom Launch Loop (think streams of orbital-velocity iron pellets criss-crossing the transfer point). Not very friendly to unannounced visitors. In this case, an attacker would probably send a big rock through first, to knock out the pellets.

daver
2003-Jul-10, 01:53 AM
There you go! Better: puch the hole in something explosive then explode.

Chemical explosives would do an insignificant amount of additional damage, and unless the ships have antimatter somewhere inside, there's probably no way to trigger an atomic explosion that quickly.

The Supreme Canuck
2003-Jul-10, 01:57 AM
Any amount of additional dammage is desirable, no matter how small it may be. It doesn't take much extra effort to aim the missile where you know fuel or munitions are stored. Even if they do not do much dammage, they are still good things to destroy.

eburacum45
2003-Jul-10, 02:49 AM
Definitely detonate the warhead before the missile gets to the enemy ship- if you detonate it inside, the momentum could carry the explosion through the ship and out the other side... as the crew should all be suited up, you won't be gaining anything by creating a small hull breach.

And use antimatter whenever you can- even if it is illegal- you do wnt to win, dont you?
Even more illegal weapons include the Strange Matter Virus (http://www.orionsarm.com/eg/s/Ss-St.html#strange_matter_virus), singularity projector, (http://www.orionsarm.com/eg/s/Si.html#singularity_projector)and conversion weapons (http://www.orionsarm.com/eg/c/Co-Cq.html#Conversion_weapons).

The Supreme Canuck
2003-Jul-10, 02:50 AM
Shoot the missile so it penetrates the hull length-wise and detonate it as soon as it penetrates. If you have a big enough missile, the explosion will move along the length of the ship and gut it.

Musashi
2003-Jul-10, 03:48 AM
Shoot the missile at the command center and then have it explode...no more command crew!

The Supreme Canuck
2003-Jul-10, 03:49 AM
Too easy. I need a challenge. :D

Musashi
2003-Jul-10, 03:51 AM
Ok, ummm, then try to take out all the weapons systems and get the hatches/airlocks to stick closed, and disable the engines. But don't do to much damage, we want to be able to salvage the ship!

The Supreme Canuck
2003-Jul-10, 03:53 AM
Sounds like a plan! But, uh, how are we gonna kill the crew?

Oh, I've got it! We set off a series of explosions around the ship that cause it to spin with so much force that the crew is subjected to 200 gs of force! But I'm not going to clean it up...

wedgebert
2003-Jul-10, 03:54 AM
If you're using realisitic space combat, then odds are you'll be lucky to get your missiles within 100 km of your target, and you can forget about hitting it directly.

Extrapolating todays technology means that space combat will take place at long ranges, hundreds of thousands to millions of kilometers. We don't have the armor to survive impacts from high velocity kinetic weapons or nearby atomic ones, at least not with giving the spaceship so much mass that it has almost no acceleration.

So bomb-pumped x-ray lasers would be a very effective weapon when attached to a missile. You just within a light second or two of your target and detonate. The x-rays would cause serious damage to whatever they hit. It's unlikely that a smaller spacecraft would even survive a single hit.

Once acclerations start increasing (and thus ranges as well) projectile weapons will start to disappear. Longer range weapons will be dominated by missiles while shorter ranges will be controlled by high powered masers and x-ray lasers.

Tuckerfan
2003-Jul-10, 04:33 AM
The book War in 2080 (http://www.amazon.com/exec/obidos/tg/detail/-/0688034268/qid=1057810970/sr=1-1/ref=sr_1_1/002-5755904-5840039?v=glance&s=books) by David Langford has a couple of chapters devoted to the physics of space combat, both hand to hand and space ship to space ship. Even though some of the information is out of date, it's still a great book.

Musashi
2003-Jul-10, 04:55 AM
Think we could get Humphrey to clean it up?

Tuckerfan
2003-Jul-10, 05:00 AM
Think we could get Humphrey to clean it up?Que?

Musashi
2003-Jul-10, 05:12 AM
Sorry,


Oh, I've got it! We set off a series of explosions around the ship that cause it to spin with so much force that the crew is subjected to 200 gs of force! But I'm not going to clean it up...

:D

Stuart
2003-Jul-10, 02:06 PM
How should space combat work with these assumptions? It seems to me that with no shields, and weapons that include fusion-bomb-tipped missiles, that combat between well-equipped navies would be a short and violent thing. If one good hit cripples or destroys any ship, targetting, sensors, and stealth become pretty damn important, and carriers hanging back from the combat and deploying small, fast missile-ships to attack the opposing fleet becomes the strategy. On the other hand, any decent size ship should carry antimissile lasers, projectile guns, and missiles, as well as ECM, which would imply that ships would have to get close to actually hit each other.

I had a long think about this. What we basically have is a situation where offensive weaponry equates to one hit = one kill. How that kill gets to happen isn't really relevent to the primary problem. At that point it dawned on me that the situation is actually quite like submarine warfare today. There, any hit is fatal (a torpedoed submarine will sink with total loss of life, even the big Russian boats) so the whole objective is to avoid getting hit. In our other space combat string, the need for dramatic tension is mentioned - the dramatic tension is right there - a target MUST NOT be hit. If it is, it dies. In TOS Balance of Terror , there is a good scene where Enterprise is running from an inbound plasma bolt that WILL destroy the ship if a hit gets scored. The tension on the bridge is palpable.

So lets look at defenses. Basically there are four categories; active, passive, deceptive and evasive.

Active Defenses These rely on active countermeasures to physically destroy the inbound threat. Their nature is hard to guess in this context since we have an undefined inbound threat. Assuming that its some sort of missile, an active defense would consist of a gun or missile based defense system that would isolate an inbound threat, identify it, determine its course and speed and then fire the defensive weapon at it. Such weapons today are the Mark 15 Phalanx or the RIM-116 RAM (the first is a gun, the second a missile). In this context such a system would be automated because humans can't react fast enough. Active systems are countered by the threat using a variety of techniques. One type of modern anti-ship missile is called a "streaker" - these move so fast that the defense system has extreme problems in making an intercept (the Russian P-270 Moskit is an excellent streaker). Other missiles are called "dancers" - these are much slower but perform intricate evasive manoeuvers to avoid the active defenses. Harpoon or Exocet MM-40 Block III are good dancers. Don't underestimate the danger of firing cheap simple and very vulnerable missiles - enough of them and one should get through - and one is all it takes.

Passive defenses Which brings us to passive defenses. These are basically concerned with limiting the effects of a hit. In the old days it was done by using heavy armor. That may not be the best approach here. The objective is to limit the effect of a hit; that could possibly be best achieved by ensuring the threat didn't explode. Its arguable that building the warship extremely lightly so that the resistance caused by a hit does not explode the warhead.. Taking that too extremes, I can see a starship design that is primarily a lightweight latticework separating individual key areas. Fast-acting airtight doors are a must - if hull integrity is breeched, they slam shut (similar doors are in the hangars of US carriers - they have no safety system. If you are in the way when they close, they will kill you. I've seen these doors cut a US$80 million F-14 in half). That means that if one of the essential areas is cut off (physically or methophorically) , it can survive on its own. Now, most radar-based guidance systems see a target as a mass of corner reflectors and use those to construct an image then home in on the geometric center of that target - so a good passive defense would be to distort the radar image so that such a guidance system would have a good chance of passing through the structure without detonating. Passive defenses are countered by spreading damage as widely as possible and trying to get multiple hits.

Deceptive Defenses that, of course brings us to deceptive defenses. This means persuading the threat that the target is either something it is not or somewhere it isn't. Deceptive electronic jamming can be used to create misplaced radar returns (extend to other forms of sensors), decoys can be used to lure threats away, others can be used to create false threats to divert an enemy. A ship can fake critical damage to lure an enemy in or conceal critical damage to trick that enemy into pulling back. A key part of all this is understanding enemy systems so they can be spoofed. That means details of sensor characteristics are critical. That, in turn, means that sensor information is going to be closely guarded and equipment rarely used to its full potential (you would be surprised how rarely an AEGIS ship turns its marvellous radars on). Deceptive defenses are countered by sophisticated sensors and good intelligence. Its critical to know exactly what the capabilities of the threat are. Food for thought, Get a military reference book and read the specs of military equipment there. Almost every single number you read is either wrong, incomplete or so generalized as to be worthless.

Evasive Defenses Evasive defenses means not allowing the enemy to know you are there. If he doesn't know you're around, he can't shoot at you. Earlier in this string there was a comment that stealth wouldn't matter. I profoundly disagree with that; "stealth" (actually reduced signature or RS) is going to be the key parameter. Remember no level of RS is going to hide the target completely; what it will do is to reduce the range at which sighting becomes inevitable. That is immensely worthwhile because he who gets seen first will get shot at first. That means they have a good chance of being hit first and one hit is all it takes. This applies in submarines today; a friend of mine who drives nuclear boats compared a duel between two SSNs of equal standard and crew training to two men fighting a duel with sawed-off shotguns at one pace range. Using evasion for tactics is a key here. For example, we have a defending formation facing an attack down a threat axis. As the threat approaches they gear up to attack. What they don't know is that sitting a little off the threat axis is a single ship with its sensors off and SR operating at max. At the appropriate moment, that ship unveils and rakes the attacking formation with missiles. Sound far-fetched? Been done. In the Norwegian Sea. No missiles were actually fired of course, but the Soviet bomber crews had kittens when they were illuminated at slightly less than point-blank range. If it had been a real shooting war instead of a little Cold War jousting, they would have been slaughtered and they knew it. Evasive defenses are couuntered by reconaissance. Old military maxim - time spent in reconaissance is never wasted.

So putting all this together, we have an environment will be a battle where the opposing fleets are continually probing and manoeuvering, pushing forward and pulling back, each seeking an opening where it can get in a shot with a good chance of succcess - also knowing that if that shot fails, retribution will be certain and final. Coming back to the dramatic tension issue, this is the real thing. A bridge crew fighting an inbound missile knowing if their defenses fail everybody is going to die. The attacking crew fighting to get their shot home, knowing that if they miss, the counterpunch will probably kill them. Beats hell out of hippies fighting with technobabble doesn't it?

Taking this a bit further, its almost certain we would be looking at the primary striking ship being mother-ship carrying large numbers of smaller units. Just so we can use modern vernacular, carriers and a stargroup of starfighters. Reason why is a bit of history. Battleships didn't become obsolete because of torpedoes or aircraft - at least not directly. Battleships became obsolete because the only way they could be destroyed was to risk another asset of equal or greater value. That meant that any conflict involving them was likely to be indecisive (because neither side could afford serious losses) . However, the evolution of the aircraft carrier meant that a battleship could be endangered by the deployment of assets (aircraft) that cost far less than it did yet could carry a weapon that could seriously hurt the battleship (a torpedo). Same applies here. If one side can threaten the other's primary assets with counters that cost far less than the target under threat, then the side under threat has a very serious problem.

Glom
2003-Jul-10, 02:37 PM
Wow, war's quite harsh. :o

Stuart
2003-Jul-10, 03:05 PM
Wow, war's quite harsh.
Nathan Bedford Forrest summed it up best. "War means fighting and fighting means killing". The whole concept of warfare is industrialised murder. Colonel Supatra once summarized it by saying that "troops do what it takes to win no more no less" then added "the hardest thing to accept is not what you did to others, it is what you did made you." That's why its so important to be good at it. Nothing is more futile or useless than a second-rate military.

TinFoilHat
2003-Jul-10, 03:54 PM
Wow!

That's given me a lot to work with. Thanks.

It looks like the only sure defense it to have the other guy not even realize you're there until it's too late.

Stuart
2003-Jul-10, 05:29 PM
Wow!

That's given me a lot to work with. Thanks.

It looks like the only sure defense it to have the other guy not even realize you're there until it's too late.

That's right - or mislead him into thinking you're somewhere else. Give you an example of that. One of the standard tactics in submarine warfare is called an "In your face shot". When the threat launches a torpedo, the counter is to fire a torpedo of your own down a reciprocal of the inbound's course. That way (one hopes) the threat will see the torpedo coming for them and take evasive action - thus breaking the guidance wires to its own torpedo and giving its target a chance to get clear. The threat's counter to an "in your face shot" is to set up its shot in a dogleg so firing down the strobe takes an in-your-face shot away from the threat submarine.

Lets apply that to a space battle. The Bad Guys are the ESS Picard (ESS = Evil Space Ship) while the Good Guys are the GGS Liberty (GGS = Good Guys Ship). The Picard is hunting Liberty which has taken cover in an asteroid field. The Liberty is moving so as to keep an asteroid between it and the Picard, thus remaining shielded from its sensors. As the Picard moves to an optimum position for the Liberty's attack, Liberty fires a missile from her stern tube - on a reciprocal to the bearing of the Picard. That means the missile is screened from the Picard by the asteroid. A split second later the missile controller on the Liberty swings the missile around so that its heading for Picard but on a course that points to another asteroid as a source. The Picard fires an in your face shot at that asteroid and moves to attack, meanwhile activating its defense systems against the onbound missile. At this point the Liberty unmasks from behind its asteroid and fires its shot at close range into the stern quarter of the Picard. With their attention focussed on the wrong bearing and a threat from a misleading direction, the crew don't spot the real attack until its too late and the Liberty's missile, a MIRV with 10 550 kiloton warheads incinerates the Picard.

So we have tactical skill and misdirection used to erase yet another hated name from the Galaxy!

(Picard really is a jerk - in reality, officers like him get fragged).

wedgebert
2003-Jul-10, 06:25 PM
Just a side note, if you're going to use realisitic combat, then the asteroids in an asteroid field won't be close enough for you use multiple asteroids like Stuart just mentioned.

The asteroids in our asteroid belt are millions of kilometers apart. (for asteroids visible from Earth). Thus, until you have excellent sensors that allow you to conduct combat at such distances, you'd just be playing hide and seek around a single asteroid.

However, I do like the idea of Picard eating MIRV.

Nightfall
2003-Jul-10, 06:26 PM
How would nanobots will fit into space combat? In a short story for for my creative writing class, I had both sides of a battle used nanobots to repair their ships after a hit. Is that plausible?

Or how about nanobots that destroy the enemy's hull?

Stuart
2003-Jul-10, 06:32 PM
Just a side note, if you're going to use realisitic combat, then the asteroids in an asteroid field won't be close enough for you use multiple asteroids like Stuart just mentioned. The asteroids in our asteroid belt are millions of kilometers apart. (for asteroids visible from Earth). Thus, until you have excellent sensors that allow you to conduct combat at such distances, you'd just be playing hide and seek around a single asteroid.

However, I do like the idea of Picard eating MIRV.

How about slingshotting a missile around an asteroid so it appears to come from a different bearing? Perhaps the Liberty could fire a missile so that it goes into a partial orbit around the asteroid the re-ignite the engine to kick it out of orbit and on its way? Would that work?

The critical thing is to make sure that Picard doesn't see the missile in time for him to surrender yet again.

TinFoilHat
2003-Jul-10, 07:25 PM
How would nanobots will fit into space combat? In a short story for for my creative writing class, I had both sides of a battle used nanobots to repair their ships after a hit. Is that plausible?

Or how about nanobots that destroy the enemy's hull?
I doubt they'll be significant. If your ship has just been blasted into radioactive fragments, no amount of nanotech is going to save you. And if you can hit your opponent with a nanite-filled-missile, you could have just as easily hit him with a nuke. Especially since the nanite-missile would have had to hit at a relatively low velocity for the nanites to survive the impact, while the nuke has no such limitation.

A lot of science fiction uses nanites as the technological equivalent of magic pixie dust, that can do anything the authors want it to. I'm trying to avoid magic technologies.

daver
2003-Jul-10, 07:31 PM
Well, to clarify my take on concealment:

Any ship doing active maneuvering will stand out like a sort thumb in a spotlight. There's no way to counter this unless you have anewtonic drives or tractors or something along those lines.

Any ship bearing life will have an IR signature that can't be cloaked. It can be masked (hide among a bunch of other hot objects), it could be concealed for a short period of time (hours, perhaps), it could be redirected so that, for instance, the side supposedly towards your enemies is roughly background, the side away very hot.

Submarines are probably the wrong image for space ships--think dirigibles.

A bad guy fleet can enter your home system in only two ways--through the jump point or from interstellar space (slow ships). Maybe, if your war is lasting centuries, the enemy could hollow out a comet in a nearby system, bury a fleet inside (soldiers in cold sleep) and launch it towards your home system. The comet would have to travel at "normal" velocities--tens to hundreds of kilometers per second--or it would be obviously suspicious when it entered your home system. So count on a journey of centuries or millenia. Perhaps it could be started out a bit quicker and use some low-emission braking system (like a Bussard ram scoop without the ram). Anyway, once the comet is in the system, the enemy fleet could be aroused and use the comet to mask their waste heat for a while. Obviously this takes advance planning. But if your enemy is into really long planning they might do something along those lines (phase 1: war. phase 2: stalemate. phase 3: negotiated peace. Enemy launches generation attack. Later, enemy launches relativistic bombardment attack. phase 4: peace. phase 5a: Sneak attack arrives, defrosts, surreptitiously scouts. phase 5b: Relativistic bombardment starts on home world, one relativistic attack coasts through jump point to clear out passive defenses. phase 5c: Sneak fleet uncloaks to secure jump point. phase 5d: Enemy invasion fleet arrives through jump point. phase 5e: war or mop-up, depending on how successful the relativistic bombardment phase was).

The relativistic bombs could be cloaked--they wouldn't maneuver once up to speed and wouldn't have any heat sources. Cold, black, and radar absorbant. The sneak fleet comes in cold, disguised as a comet. When they wake up, they start generating heat, but they could use the comet as a heat dump for a while. Once they're out and maneuvering, anyone watching inside the system knows where they are. The tactic is to ensure that most of their forces are concentrated somewhere else (like trying to divert the relativistic bombs) while they secure the jump point.

wedgebert
2003-Jul-10, 07:47 PM
Remember that IR radiation and "heat" are not the samething. You could easily coat a ship in something that is opaque to IR radiation and thus reduce the IR signature of the ship.


I think submarine warfare is probably the best analogy for space combat that we have. At least until we start to develop new sensors (gravity sensors) or increase the detection capabilities of our current ones.

If we ever develop a detection system that allows for reliable detection well outside of weapon range, surface ship combat will become the new analogy.


Also, I doubt nanotech will have much effect on a starship's repair abilities. People talk about "growing" new starships/buildings/whatever when we have nanotech. However, that's not a very efficent way of doing things. For one, growing a new item would introduce many flaws into an item since you have billions of nanobots that are all at work at the same time. Even if they are communicating, they're still going to be out of sync or something.

TinFoilHat
2003-Jul-10, 07:57 PM
A few thoughts of mine:

A fusion drive, with its million-degree-plasma exhaust, is going to be pretty damn impossible to hide. It's likely that ships trying to manuever stealthily would have a lower-temperature, lower-ISP show manuevering system, only switching on the main drive when they've already been spotted or revealed themselves.

Thermal control is a major issue. Submarines don't need to worry about this, they're sitting in an infinite heatsink. Real spacecraft need to carry cooling loops and sizeable radiators to keep cool, and this will only get worse as ships get larger (less surface area per mass) and start carrying multi-gigawatt fusion plants onboard. A smaller ship can probably hide by having very good insulation and a directional heat-dump system - but this assumes you know roughly what direction your opponent is in. Time spent being stealthy may be limited to how long you can go before overheating. This is a huge problem with Star Trek style cloaking devices - where is your ship's waste heat going? Then again, I don't think I've ever seen reference to a cooling system or radiator of any sort on any Trek ship.

Given the way I'm defining FTL travel to work - "jump points" where a ship can only enter or exit FTL travel in small regions of space - most military planning will end up as strategies for defending or taking these points. I suspect, with this kind of bottleneck, the advantage will be heavily on the defending side, with full fleet engagements between established powers being very rare.

jamestox
2003-Jul-10, 08:05 PM
...Liberty fires a missile from her stern tube - on a reciprocal to the bearing of the Picard. That means the missile is screened from the Picard by the asteroid. A split second later the missile controller on the Liberty swings the missile around so that its heading for Picard but on a course that points to another asteroid as a source. The Picard fires an in your face shot at that asteroid and moves to attack, meanwhile activating its defense systems against the onbound missile. At this point the Liberty unmasks from behind its asteroid and fires its shot at close range into the stern quarter of the Picard. With their attention focussed on the wrong bearing and a threat from a misleading direction, the crew don't spot the real attack until its too late and the Liberty's missile, a MIRV with 10 550 kiloton warheads incinerates the Picard.


Problem here...you can't just curve a missile in space the way you steer a wire-guided torpedo. Straight-line action and reaction, you know. It'd be easier to just use low thrust motors on the missiles to put two or three in a low asteroid orbit - converging on the approximate area of the Picard with the missiles' onboard computer and sensor suite to activate as soon as the Picard is above the asteroid's "horizon". Thrusters align the missile's main drive for the terminal guidance "sprint" and the computer arms the warheads. The main drive lights off for the several seconds it takes to alter the orbit, the five MIRV warheads eject from each missile's carrier bus in a slightly divergent path that encircles the Picard from several different directions. The resulting hard radiation from the multiple, simultaenous explosions kills all crew... the EMP destroys all electronic systems onboard; it wouldn't be necessary to literally "incinerate" the ship - a near-miss would be more than enough.

And Picard never knew what hit'em.

Even if they detected all the inbound warheads, it would probably only take one or two to incapacitate the crew and/or ship. At the very least, one explosion anywhere in the general area would "blind" the Picard's sensors, making it easy prey. In space, you can "shoot around the corner."

For that matter, rather than MIRVs, you can literally put a 55 gal drum of large gravel in the nose of each missile, with a "bursting" charge in the bottom as the warhead. Can you say "giant buckshot?" This kind of "kinetic kill" system has no defense aside from trying to leave the kill zone as quickly as possible! Even if a weapons control system COULD lock on and destroy each rock, it'd still be a threat even in it's smaller form. Of course, once the Liberty fired such a weapon, she'd have to break orbit immediately, since the remains of the "buckshot" would orbit back to her shortly...

JT

daver
2003-Jul-10, 09:34 PM
Remember that IR radiation and "heat" are not the samething. You could easily coat a ship in something that is opaque to IR radiation and thus reduce the IR signature of the ship.




That's not my quote. Maybe you got too aggressive in trimming? Regardless, the waste heat needs to be radiated away--you might succeed in modifying the frequency somewhat, but it would still be detectable. I'm guessing here, but i'd figure a reasonable ship should be detectable by another ship by its thermal signature out to several million kilometers (obviously this depends on the size of the ship and telescopes being used). It would be a mistake to assume huge advances in fusion technology and none in detector technology.




I think submarine warfare is probably the best analogy for space combat that we have. At least until we start to develop new sensors (gravity sensors) or increase the detection capabilities of our current ones.



I disagree. The ocean is a noisy place, submarines can hide below a thermocline, submarines are capable of silent travel and maneuver. A space ship can be stealthy to some extent, but such stealth operation has an extremely high cost.

A spaceship can hide next to a planet or other heat source. A space ship can move at a snail's pace (months between planets if they happen to have the proper alignment) without exposing itself; such concealed movement is easier if there's only one unsuspecting target and it knows where the target is. If a spaceship wants to maneuver relatively quickly or launch an attack, it more or less immediately exposes itself.




If we ever develop a detection system that allows for reliable detection well outside of weapon range, surface ship combat will become the new analogy.


Also, I doubt nanotech will have much effect on a starship's repair abilities. People talk about "growing" new starships/buildings/whatever when we have nanotech. However, that's not a very efficent way of doing things. For one, growing a new item would introduce many flaws into an item since you have billions of nanobots that are all at work at the same time. Even if they are communicating, they're still going to be out of sync or something.

I agree about nanotech--it's probably best to say that it didn't live up to its promise and ignore it.

Fleet-fleet battles are going to be extremely expensive. Most likely, the first ships through the jump point are going to be cut to ribbons by the jump point defenses. I'd imagine the first ships through are going to be huge lumbering rocks; some of these rocks will have weapons systems. Eventually they could take out enough of the jump point defenses for your main ships to come through (some of the defenses would likely be fairly stealthy, in the hope that they could survive long enough to take out the capital ships).

eburacum45
2003-Jul-11, 12:13 AM
Any well defended solar system will have a network of active and passive sensors, radar and lidar, Forward mass detectors and gravity wave detectors- nothing larger than a pebble will be able to move in a highly civilised solar system without it being detected.
This is why many battles will have to be fought in semicivilised solar systems where total networks of mass detection have not been established.

To attack a civilised system totally covered by detection systems only tiny weapons like nanotech would work- and these are a slow, subtle weapon, taking months to sabotage weaponry, sensors and drive control systems; they are also not very powerful physically, and would take a long time to dissasemble a hull of a spaceship, so are not very useful in head on attacks.
To utilise nanotech weapons you have to attack like a virus, not a tank commander; to defend against it you have to emulate an antibiotic, not a Patriot missile operator.

Stuart
2003-Jul-11, 01:18 PM
Any ship doing active maneuvering will stand out like a sort thumb in a spotlight. There's no way to counter this unless you have anewtonic drives or tractors or something along those lines.
Surely this applies only if a ship is under constant power but from what I can gather on the space environment this isn't so. Once an acceleration is applied to a ship it will continue at the velocity obtained until a counter-acceleration is applied. So here, a ship could accelerate in a position where its masked from enemy sensors and then coast from that point onwards.


Any ship bearing life will have an IR signature that can't be cloaked. It can be masked (hide among a bunch of other hot objects), it could be concealed for a short period of time (hours, perhaps), it could be redirected so that, for instance, the side supposedly towards your enemies is roughly background, the side away very hot.
Very, very good point. In fact, this is a major problem with signature-reduced aircraft today (please leave that there). Its another serious tactical consideration for the crew isn't it - they have a very severe time limit for an engagement before their thermal emission control system overloads and they are forced to unmask. Another great issue of dramatic tension - the crew deseperately trying to complete their mission while the clock remorselessly ticks down to thermal overload time.


A bad guy fleet can enter your home system in only two ways--through the jump point or from interstellar space (slow ships).
This suggests attacks by infiltration (the need for intelligence - electronic and otherwise also requires that). It also assumed the need for major exploration to detect new jump points - perhaps some that give back doors into a system (for example the evil Federation attacks this worthless system and that worthless system in order to gain access to a third worthless system that has an unguarded wormhole that leads to a strategically-critical system. This means the strategists are going to be working overtime trying to figure out what all the moves actually mean. Another implication is that once highly-stealthed ships are in a system, its going to be a job rooting them out


The sneak fleet comes in cold, disguised as a comet. When they wake up, they start generating heat, but they could use the comet as a heat dump for a while. Once they're out and maneuvering, anyone watching inside the system knows where they are. The tactic is to ensure that most of their forces are concentrated somewhere else (like trying to divert the relativistic bombs) while they secure the jump point.

That's a possible tactic. The real lesson here reinforces the point that battles are going to be fought with misdirection, misinformation and deception as important as any "killing" weapon.

Stuart
2003-Jul-11, 01:29 PM
Problem here...you can't just curve a missile in space the way you steer a wire-guided torpedo. Straight-line action and reaction, you know.
I'd use a thing called pif-paf. This is basically a ring with ports that can be opened and closed by computer and a central gas reservoir. The computer determines what course change is required and which ports need to be opened to bring the missile nose to the appropriate angle. The gas reservoir then emits high-pressure gas through those ports then, when the required course change is being met, the computer closes those ports and opens new ports to kill the swing. This system is used already on a missile called ASTER. It appears to work quite well.


For that matter, rather than MIRVs, you can literally put a 55 gal drum of large gravel in the nose of each missile, with a "bursting" charge in the bottom as the warhead. Can you say "giant buckshot?" This kind of "kinetic kill" system has no defense aside from trying to leave the kill zone as quickly as possible! Even if a weapons control system COULD lock on and destroy each rock, it'd still be a threat even in it's smaller form. Of course, once the Liberty fired such a weapon, she'd have to break orbit immediately, since the remains of the "buckshot" would orbit back to her shortly..

Sure but nukes are cool - I love nuclear weapons. The problem with the buckshot idea is that its great against an unarmored target but I suspect it would be practical to armor against it. Maybe a solid armor, maybe a layered protection system that uses a mixture of liquids and solids to defeat the inbounds (this is passive defense at work). Another use of the gravel idea would be an anti-sensor weapon - shotgun the outside of a ship and the sensors will be damaged. Hmm. Related to that, how's this for an idea. In addition to the gravel, the charge contains a beacon that attaches to the hull. That way, when the crew think they've dived into signature-suppressed mode, the beacon is still revealing their position.

Stuart
2003-Jul-11, 01:49 PM
I'm guessing here, but i'd figure a reasonable ship should be detectable by another ship by its thermal signature out to several million kilometers (obviously this depends on the size of the ship and telescopes being used). It would be a mistake to assume huge advances in fusion technology and none in detector technology.
Thermal scanners are a lot better now than most people think. The problem will not be picking up a heat signature, its disentangling the heat signature we want from all the others. That's not a sensitivity issue, its a signals processing issue - and a hellishly difficult one.


I disagree. The ocean is a noisy place, submarines can hide below a thermocline, submarines are capable of silent travel and maneuver. A space ship can be stealthy to some extent, but such stealth operation has an extremely high cost.
We know how noisy the ocean is because we're trying to disentangle the sound signature of a submarine from the sound signature of everything else. Likewise thermal. It is possible to pick up the thermal wake of a submarine - the thermal scar left on the surface by a submarine travelling underwater. Even a submarine a few hubdred feet down leaves a detectable scar on the ocean surface. In fact, that scar can be detected by satellite. At first glance, that appears to offer a perfect means of detecting submarines, tracking them and steering prosecution assets into the attack. The catch is it doesn't work. There are so many other thermal scars on the ocean that its impossible to isolate the ones we want from all the others.

At the moment we're not really looking at space, we're looking through it. When we start trying to detect faint signatures at extreme ranges with an intelligence at the other end trying to stop detection from taking place, I suspect we'll find space is a very "noisy" environment.


I agree about nanotech--it's probably best to say that it didn't live up to its promise and ignore it.
Agree absolutely.


Fleet-fleet battles are going to be extremely expensive.
You bet. Full-scale battles are going to be horribly costly, so much so that they'll only be undertaken as a last resort. Again we come back to strategy, deception and misdirection. Systems will be "conquered", not be destroying the defenses but by making the effort to defend them more costly than they're worth. Defense would work the other way - make the system so horribly costly to attack that its not worth the effort. That, of course, means prioritization. Some systems will be defendable only at the cost of leaving others vulnerable.

Another implication of this by the way. Veterans of space battles are going to be rare - to be a veteran means being a survivor and there won't be that many. That means a veteran is going to be a VERY respected character. These wars are going to be dreadfully Darwinian - few crews will survive their first battle but the ones that survive three or four are going to be feared experts. In fact one can see ambushes being set simply to kill such crews (another dramatic tension situation).


Most likely, the first ships through the jump point are going to be cut to ribbons by the jump point defenses. I'd imagine the first ships through are going to be huge lumbering rocks; some of these rocks will have weapons systems. Eventually they could take out enough of the jump point defenses for your main ships to come through (some of the defenses would likely be fairly stealthy, in the hope that they could survive long enough to take out the capital ships).
Another tactic - toss a really, really large weapon (there is no upper limit to the sheer power of a thermonuclear initiation) through the wormhole so that it detonates as it emerges. That may not destroy much but the flash and sleet of radiation will disable sensors and allow the attackers to get their first ships in. More dramatic tension - the crews of the defending ships waiting for the unimaginable explosion that will signal the start of the battle for their system.

You know what's really sad - this thread has been running - three days now? - and between us we've come up with more good plots and ideas than the DS9 scriptwriting crew did in their whole Dominion war story arc.

eburacum45
2003-Jul-11, 03:02 PM
If you are going to rely on misdirection you would best send a fleet of expendable unmanned craft, with the same mass and radar signatures as the manned craft. As most targetting will be automated anyway, the unmanned ships might be better shots than the manned ships, while you can use manned craft to carry out the real objective (whatever that may be).

Eventually the automated ships will take over all warfare functions, and perhaps become so efficient that any attack becomes an act of Mutually assured destruction;
but for a brief golden age, no doubt human warships will be both successful and necessary.

Stuart
2003-Jul-11, 04:57 PM
If you are going to rely on misdirection you would best send a fleet of expendable unmanned craft, with the same mass and radar signatures as the manned craft. As most targetting will be automated anyway, the unmanned ships might be better shots than the manned ships, while you can use manned craft to carry out the real objective (whatever that may be).
Absolutely. In fact. we're rapidly going that way now. with Predators carrying Hellfire air-to-surface and Stinger air-to-air missiles. The early air operations over Baghdad reflected similar thoughts. In our proposed space war, I believe the remote-piloted (the word unmanned has been stricken from the Pentagon phrase book as politically incorrect) vehicles are utterly crucial both as decoys and as attack craft. Correctly combining the capabilities of RPVs and human-operated craft is likely to be crucial to winning.


Eventually the automated ships will take over all warfare functions, and perhaps become so efficient that any attack becomes an act of Mutually Assured Destruction; but for a brief golden age, no doubt human warships will be both successful and necessary.

MAD never was US policy by the way. Be that as it may, I don't think humans are ever going to be displaced form the combat loop although they may be separated from it by distance. In the environment here, I see the human crews as being rather like spiders sitting in the middle of a web of sensors, RPVs etc.

daver
2003-Jul-11, 07:12 PM
Any ship doing active maneuvering will stand out like a sort thumb in a spotlight. There's no way to counter this unless you have anewtonic drives or tractors or something along those lines.
Surely this applies only if a ship is under constant power but from what I can gather on the space environment this isn't so. Once an acceleration is applied to a ship it will continue at the velocity obtained until a counter-acceleration is applied. So here, a ship could accelerate in a position where its masked from enemy sensors and then coast from that point onwards.

Agreed in principle. A lot depends on the scenario. The ships are probably half fuel, and have a lot of delta V to play with (on the order of a thousand km/sec); big ships may be more limited in acceleration. If space combat uses big chunks of that delta V, solar systems get pretty small (possibly roughly analogous to the size of Earth to a modern navy), but stealth gets VERY difficult. If you could plan on a campaign lasting months, and had a way to be sure that your opponents would be in a certain place at a certain time, you could launch some sort of stealth attack.




Any ship bearing life will have an IR signature that can't be cloaked. It can be masked (hide among a bunch of other hot objects), it could be concealed for a short period of time (hours, perhaps), it could be redirected so that, for instance, the side supposedly towards your enemies is roughly background, the side away very hot.
Very, very good point. In fact, this is a major problem with signature-reduced aircraft today (please leave that there). Its another serious tactical consideration for the crew isn't it - they have a very severe time limit for an engagement before their thermal emission control system overloads and they are forced to unmask. Another great issue of dramatic tension - the crew deseperately trying to complete their mission while the clock remorselessly ticks down to thermal overload time.

But unless you have a truly massive body like a comet to dump your waste heat into, your cloaked time is going to be measured in hours, while your transit time from a low observability drive is going to be measured in months.

Inventive minds will find a way around this; such tricks will probably only work once.



A bad guy fleet can enter your home system in only two ways--through the jump point or from interstellar space (slow ships).
This suggests attacks by infiltration (the need for intelligence - electronic and otherwise also requires that). It also assumed the need for major exploration to detect new jump points - perhaps some that give back doors into a system (for example the evil Federation attacks this worthless system and that worthless system in order to gain access to a third worthless system that has an unguarded wormhole that leads to a strategically-critical system. This means the strategists are going to be working overtime trying to figure out what all the moves actually mean. Another implication is that once highly-stealthed ships are in a system, its going to be a job rooting them out


Yeah, i was thinking about hidden jump points. In the Codominum universe, jump points seemed to be pretty obvious (the Moties knew they had a jump point in their system, they just didn't know where it led). If this is the case in this scenario, it's unlikely that there will be back doors into any settled systems.

But isolation of civilizations through the conquest of weakly defended jump points seems like a good scenario. Given jump points, there is probably some economic incentive to interstellar trade (3He probably wouldn't be a trade item--in the event of a war 3He plants could be set up around gas giants or just from nuking lithium. But maybe some systems have better access to minerals needed to produce the drives. Exotic foods, drugs, spices, and information could be traded).




The sneak fleet comes in cold, disguised as a comet. When they wake up, they start generating heat, but they could use the comet as a heat dump for a while. Once they're out and maneuvering, anyone watching inside the system knows where they are. The tactic is to ensure that most of their forces are concentrated somewhere else (like trying to divert the relativistic bombs) while they secure the jump point.

That's a possible tactic. The real lesson here reinforces the point that battles are going to be fought with misdirection, misinformation and deception as important as any "killing" weapon.

Yes. "There's no such thing as ineffective brute force, just insufficient brute force." But sneakiness is a lot cheaper.