What future space combat would really look like | Hacker News Reader

What future space combat would really look like

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330 pointsdikarel231 comments

There are three fundamental problems I see here:

1) Why put humans on warships at all? Algorithms are probably better at it. Computers would obviously do the heavy lifting anyway (calculating burn times). An algorithm knows no fear, shows no mercy, and does not flee or surrender unless programmed to do so. The only thing left is target selection, and it doesn't seem worth bringing a human along just for that.

2) If you don't need to put humans on warships, then you quickly realize you don't need a warship at all. Just send a bunch of missiles from wherever the warship would have launched. It's harder to take them all out at once with a "mine" or something. You also get to build more missiles if you don't need to build the warship. Sure, you might attach a collective nuclear rocket "booster" to many missiles to build that initial velocity. There's no need for that rocket to be anything more than an engine temporarily attached to the missiles. It's also not really required to begin with.

3) If you're sending lots of missiles, there's no reason for them to be any larger than the smallest size permitted by design and manufacturing practicalities. For something that amounts to a liquid-fueled rocket, that smallest size is preposterously small. A liquid-fueled rocket can be fit into an object the size of a soda can with current technology. This makes the notion of point defense completely laughable: divert ten thousand missiles out of one hundred thousand, and you've reduced the incoming energy by 10%.

On the same idea of not having humans I have been wondering when when we will see a war type video game where you play drones be it land air or sea rather than soldiers on the ground or flying a plane. The cost of sending humans is so high just around our little planet that I can't see how anyone would want to inject humans into any space attacking where the costs as mentioned in the article are so much higher.

RTS games have the player directing an army of autonomous AI-controlled drones. In a game like Supreme Commander they don't even pretend to be people.

> Why put humans on warships at all?

The whole idea of the article is to explore what's possible with current technology, and general-purpose AI is not part of that. Guided missiles are routinely defeated by counter-measures even when the flight only takes minutes.

How would having humans a few light-seconds away from the missiles be able to help with that?

Eh? My point was that humans on board can improvise (remember Apollo 13) and carry out their objectives even in the presence of a forewarned and intelligent opponent.

The real reason, of course, is that war is just so much cooler when people are dying. Sources: G. Carlin.

Honestly, though, I fully expect AI to advance sufficiently in the next 20 years that a 10s delay is sufficiently small, and the AI can handle anything likely to occur in under 20s on its own.

>I fully expect AI to advance sufficiently in the next 20 years

Yes, people have been expecting AI to become human-like within 20 years for the past 6 decades.

http://en.wikipedia.org/wiki/History_of_artificial_intellige...

("Researchers expressed an intense optimism in private and in print, predicting that a fully intelligent machine would be built in less than 20 years")

Did you read the rest of his post? He didn't predict general intelligence within the next 20 years. Rather, he predicted that the special purpose weapons AI would be sufficient to handle the sort of latencies that would happen in some hypothetical space combat.

Perhaps I'm reading your posts wrong, but it seems a fairly conservative prediction to me.

We're talking about replacing people in combat vehicles with AI. Considering the need for tactics, strategy and improvisation in a conflict that can take place light-years away, that won't work with anything less than general-purpose AI.

Where is anyone talking about conflicts light-years away? I think we may be discussing different things. The article itself concentrates on intra-system conflicts, primarily because it is trying to deal with realistic space combat using current technology. FTL drives are not part of that paradigm.

Yes, obviously if something is light-years away you would need to develop general purpose AI to make those decisions or send a command ship with a human crew to the location, but the post you are replying to was discussing 10s to 20s delays associated with local space combat.

> The article itself concentrates on intra-system conflicts

Neptune is more than 4 light-hours away, and the Oort cloud (discussed as a possible source of projectiles) a full light-year further. So I don't see how anything short of general purpose AI can be tele-operated for intra-system conflicts.

Again, why does it require general purpose AI?

The two examples you cherry-picked are the furthest objects in our solar system. You've literally picked the outlying examples and made them the rule.

The same "problem" could be solved by sending a bunch of what are essentially missiles-carrying-missiles with algorithms that boil down to orders to shoot at any objects that are hot or fast moving or match certain radar signatures. This technology has been in place since the first heat-seeking missile... 1956! There are plenty of other solutions that do not require a general AI (such as sending command ships out).

The point is that the 10-20 seconds latency that was mentioned is not even close to covering the next planet, much less the entire solar system. Yes, you can send off a bunch of heat-seeking missiles, but, as I mentioned in my original post way up this thread, these missiles are routinely defeated by counter-measures even when seconds away from the target. So, in the absence of strong AI, it's vastly more efficient to actually have a few humans on board the ships.

So, in the absence of strong AI, it's vastly more efficient to actually have a few humans on board the ships.

Have you done the math on that? Humans (and more importantly their life-support systems) are hugely, hugely expensive in terms of the carrying capacity of a space ship.

There's also the rather large cost in reduced maneuverability when you want your on board humans to be able to survive.

How does a human-operated ship mitigate anti-missile counter-measures better than an AI operated ship, assuming the same munitions? You have yet to give a single concrete example. If anything, a human-operated vessel would have a worse reaction time than a machine-operated vessel (or AI-operated if you want to be romantic). This is simply due to the physics of operating a biological construct to mechanically manipulate things instead of an electronic construct to manipulate much smaller things on a much smaller level.

And to sum up, you've used these as synonyms in the argument:

strong AI

general-purpose AI

human-like AI

These are completely different things. What, exactly, are you referring to?

Huh, why do you require human-like AI to control a bunch of high-velocity objects, calculate intercepts, and release other high-velocity objects on those intercepts?

The only human-level decision that needs to be made is simply confirming the object is a target and should be attacked.

Most people haven't served in the military, but have you ever played a war game? Deciding where to move the weapons platforms and which objects are targets for what is the very essence of fighting a successful battle.

Have you ever played against the AI in Starcraft or other countless video games with AI?

And? If you are 10 light seconds away from a battle your round trip control delay is 20s. Also, if weapons are zipping around at 2,000 km/s then 10 light seconds is only 25 minutes flight time. We certainly won't have 2,000 km/s projectiles in 20 years but in 100 we might.

Ah, I see. Here's the thing: when you're sitting in a glorified tin can far from any resources or support, you don't have a whole lot of options. The great triumph of Apollo 13 was simply not dying. It was a great triumph, but it's not like they completed the mission of landing on the moon in the face of multiple mechanical failures.

What, exactly, would a warship do after realizing that the plan had failed? Their options are basically: run, surrender, die. Running is not even an option given current technology. It's not like they can ditch the ship and land somewhere. It's not like they can hide or fake destruction. They are sitting in a glorified tin can, which is (as stipulated) unable to follow the parameters of the mission. About all they could do is select a different target.

If you want the capability to improvise, the best (and really only) option is the saboteur. I suspect saboteurs would play a substantial role in interstellar warfare for that reason.

Oh, come on. Tank and plane crews are also "sitting in a glorified tin can", but that didn't preclude, say, WW2 from being vastly more strategic than any preceding conflicts. The crew still has to decide where and how the vehicle moves, what targets to fire at, with which weapons, which field repairs can and should be done etc. etc. etc.

Tank and plane crews are also "sitting in a glorified tin can", but that didn't preclude, say, WW2 from being vastly more strategic than any preceding conflicts.

That was because military doctrine had adapted to the invention of radio at that point. That would actually go away at the kind of distances we're talking about. Thirty-second communication lag is enough to ruin the command battlefield view.

Almost all of those things were actually decided by the officers commanding the tank / plane battalions, not the crews of the tanks themselves. Those officers had unprecedented battlefield knowledge. None of this would be true of spaceships.

That's not even considering that spaceships operating at interplanetary speeds have far smaller effective maneuvering envelopes than any WW2 vehicle. Even the clumsiest terrestrial vehicle can turn around and leave. A realistic spaceship cannot, unless it had planned for it in advance.

>Almost all of those things were actually decided by the officers commanding the tank / plane battalions

You'd be surprised:

http://en.wikipedia.org/wiki/Battle_of_Villers-Bocage#Mornin...

It's an interesting read, but that scenario could only occur due to imperfect information. With nearly-perfect information (like what would be available in space), the German defenders would have been mobilized ahead of time, and it would have been a straightforward battle.

Read the entire section... the point is about what Wittman did with a single tank and no orders from his superiors. Yes, he had radio on that tank.

I did read the entire section. My point is that the whole scenario only arose due to an information gap.

The major problem (which is addressed in the article, by the way) is that once you've set a course you can't really change it much at all. Newtonian mechanics really limits your options here. Warships and space battles would be completely preprogrammed: detect enemy ship; set course for enemy ship; accelerate to maximum velocity; attempt to kill enemy ship with automated systems and not die as you shoot past.

This isn't really an "engagement" as we think of it now, it's more of just a fire-and-pray scenario.

Once you fire a rifle, everything is also Newtonian and deterministic. You still have to move into position, decide which target to fire at, with what ammo etc

What you describe is quite close to an actual weapon used in WW2, the SG 500:

http://en.wikipedia.org/wiki/Jagdfaust

All of those things have mathematically optimal solutions given known information. It should be trivial to solve the system.

That does not follow. See TSP.

It doesn't follow in every case, but here the calculations are things like missile ranges, acceleration values, maximum speed, etc. These all seem to be rather simple Newtonian calculations.

Basically the problem dilutes down to: plot an intercept course, fire weapons, rinse, repeat.

Why do we use drones piloted by humans?

I think given the sophistication of modern financial algorithm and counter-algorithms, it's easy to see why humans will always be necessary to wage war even if they're not on the ship. Perhaps, yes, aircraft carriers will be reduced to remote proxy bases for drones and missiles, but I imagine humans will always be at the helm even if the helm is miles away.

Why do we use drones piloted by humans? Because guided missiles are expensive, dumb rockets are cheap, and drones (while expensive) are recoverable. We want someone empowered to cut and run, so that we don't lose the drone. At the distances that spaceships would need to battle, you need to use autonomous guided missiles anyway. The lightspeed communication delay would rather defy the point of any sort of remote-piloted drone.

Also because the guidance-in-atmosphere problem is much more difficult than the guidance-outside-atmosphere problem.

You are thinking of a space ship as similar to an airplane, a tank or a ship.

In truth it is more analogous to a bullet or bomb - point it in the right direction and try and get it there as fast as possible.

Are you sure about that? Last I knew, interceptors hardly ever succeeded against guided missiles unless the missiles actually had locater beacons on them. Defenses that work are to create decoy targets (against simple guidance systems like heat-seeking) or to spoof a cancel order on the control channel. Neither seems likely to hold against a really capable attacker.

I think they main reason the author 'puts' humans in ships is because of when the article was written - 2005. Simply put, drones are a new idea that hadn't really crossed many peoples minds until they started popping up in the military.

Beyond that I think it's a pretty well reasoned piece.

I think Banks' The Algabraist got it about right.

In fact, that whole book is crammed full of good "things we currently believe to be true about physics extrapolated as far as theoretically possible" ideas:

  "How do you navigate this thing?"
  "Point."
  "Point?"
  "Yes, point.  It's all about having enough power.
   Fiddling around with calculations about DeltaV is really
   just a sign that you don't have enough power."

"It's all about having enough power."

That really does sound like the name of a Culture GSV.

[Correction - No Culture ship would be quite so lacking in gravitas, so I suspect a more likely name would be "Fiddling around with calculations about DeltaV"].

I would say there is a good chance that a GSV would have no gravitas and that a GCU would have very little gravitas indeed.

Let me second this recommendation that anyone with a genuine interest in this topic check out The Algebraist; it's a truly excellent book. I wouldn't say it's Hard SF but it's pretty firm and, IMO, a far more considered and imaginative vision of viable-ish space battle than the linked article manages.

I mean, the article hardly even mentions antimatter, aka the most potent energy store in the known physical universe, aka God's battery. Who's going to be frigging around with some stupid dirty fission reactor when the local Dyson Sphere is producing cheap (by military standards) AM by the kilo?

The author underestimates guns while overestimating "kinetic missiles". Speed imparts a lot of energy, but it wont transmit all of that energy to the target. You'll have a <missile diameter> hole in the ship.

Your ships are closing at 1000km/s and your cloud of missiles have a 10km/s Delta? A cloud of slugs would be almost the same, and you could put up a lot more of them. Of course a hybrid approach is likely, with shrapnel filled missiles. Better to impact like a shotgun than a needle.

Edit: Also gets it wrong on point defense. If you have enough energy weapons to mount an effective defense you'd make yourself such a large/vulnerable target that you'd be impossible to miss. Once again putting a cloud of slugs in the path of an inbound missile would be easier and more effective. With the speeds/distances involved all of the missiles would be approaching from a very narrow cone, and a small deflection would mean a miss.

Railguns are worthy of note, but would likely only be worthy of PD weapons. The problem with guns is that your target moves. With the exception of missiles, every fraction of the speed of light slower your weapon is, the bigger chance you take of missing. With a round fired at .1C over 300,000KM (1 light second) you need to account for about 11 seconds of lead on your target. That's 11 seconds that they don't change their course enough for you to miss. Compare this to a laser where it's 1 second of lead.

> With the speeds/distances involved all of the missiles would be approaching from a very narrow cone, and a small deflection would mean a miss.

Not necessarily. Unless space battle becomes solely a chasing game (which would favour the defender as if you know you're a runner the majority of your PD's will be aimed out your ass). A missile can sit for any amount of time after being dropped before firing. This means you can distribute a missile or approach from opposing angles. If your ship uses turrets for PD then you know it cant easily shoot two different angles at once. If you're fighting well within your missiles ranges (because fighting at maximum range gives too much time for PD's) then it'll be very easy to launch your missiles around your target in a flank attack.

Space combat seems pointless to me.

What exactly would they be fighting over?

Presumably you want to reach space for resources, so asteroids, planets and moons with minerals, stuff like that. You might also want planets/asteroids/moons that are 'good' for colonization (easily terra formed or already life sustaining).

You probably wouldn't see many fights where you are firing at the resource itself. No one with the money to fire at earth, will actually fire at earth, because it is more valuable as an inhabitable planet. If each side can obliterate whatever is being fought over, you basically have an instant MAD scenario.

Similar with moons/asteroids. I'm not going to fire a massive kinetic weapon at a moon or asteroid (and blow it to pieces) if my objective is obtain that object to profit from it. More likely I'll pay people very well to infiltrate and sabotage it, repeatedly. I wouldn't even bother trying to invade.

Why not an invasion force? Well, you could send an invasion force, but that would be fairly pointless. It is easy to defend an entrenched position that your enemy does not want to shoot at (sabotaging just the defenses might be too obvious, and i think would have too high a possibility of failure). On top of this they can use massive force to repel you, and you cannot (you don't want to obliterate your objective). So an invasion fleet is probably not likely.

A far more likely scenario would be to simply drive your competitor out of business. If they keep getting sabotaged, it becomes unprofitable for them to operate (it becomes a 'cursed' outpost, wages go up, you have to make repairs). Then you can easily take their stuff (or buy it on the cheap when they are going out of business).

This gets you into interesting things, you would end up with extensive background and history checks, genetic tests to prove that you really are who you say you are, mental/psychological screening, mind-reading, brainwashing, complex hacking of the computers that do background checks, genetic 'doping' to make a person pass as someone else, brainwashing.

Your competitors will also likely try to assassinate you if they every figure out that you are the one ordering the destruction of their outposts (it should be easy to figure out, as there will be few entities with resources to profit from this).

What if the goal is to eliminate the planet-side species?

Plus I'm willing to bet you could obliterate the surface of the planet using kinetic weapons and still have plenty of resources left over.

Why would that ever be a goal?

we like trees, so we kill all the birds (etc) who live in the trees.

Because people are irrational. Why did Hitler try to kill all the Jews? Because he felt like it and had the means to do something about it.

It was for racial purity. At the time eugenics was a big deal, it stated that some genes which were exhibited as external traits were superior. Hitler was attempting to create a better world by performing artificial selection.

As much as his ideas and methods were bonkers and would never work the fact that humans have stopped evolving naturally is something that some people still want to change.

More information: http://en.wikipedia.org/wiki/The_Holocaust#Development_and_e...

People are still evolving. Evolution is adaption to existing conditions and is basically impossible to stop. In fact dispute billions of years of multicellular evolution the cells 'in your body' and given time will develop into cancer, then portable cancer inside your body, and given the right conditions portable cancer outside your body.

PS: Humans closet genetic relative is a single celled organism whose species started from cultures of a woman's cancer cells. http://en.wikipedia.org/wiki/HeLa Tasmanian devils suffer from a similar disease of more natural oragin. http://animals.nationalgeographic.com/animals/mammals/tasman...

Maybe they are spreading "propaganda" or have "weapons of planet destruction" and we can't let that unpredictable species have them!

Why wouldn't it be a goal? If you're fighting over space resources and destroy their space-based military, then its safe to assume the planet bound will soon be launching missiles at you.

The obvious plan is glass the planet, spend 50 years harvesting the orbital resources and then you'll have the infrastructure in place to strip mine the lifeless planet.

You should read The Killing Star: https://en.wikipedia.org/wiki/The_Killing_Star

Spoiler Alert!

In the late 21st century, Earth is at peace, sending fleets of Valerie spacecraft to the stars. Without warning, relativistic kill vehicle obliterate the surface of every planet, and a mop-up fleet of ships begins hunting down the humans that remain.

The last two humans on Earth are kept as zoo specimens. They ask why their planet, and all its species, were exterminated. The squid-like aliens explain their logic thusly:

1. Every space-faring civilization is capable of planetary extermination.

2. If given the choice, every species will choose to exterminate another species rather than their own.

3. Each side knows that the other has the same choice.

Classic case of MAD. "The only winning move is not to play".

The problem is that any development of interstellar vessels constitutes "playing".

i imagine each planet/unit of an inter-system civilization will not be self-sufficient. seige, baby. i think a study of earth's military tactics and goals will answer the questions raised by this post.

You should definitely play EVE Online. This is totally the kind of stuff that goes on in the major corporations that players set up.

You can argue this over in your head a lot, but it's really quite simple in my mind.

If we assume space travel becomes relatively easy (that is to say it is used for more than initial colonization) there will be interstellar commerce. If there is unprotected commerce, there will be pirates. Any time there are pirates, protection will develop. Let us call these peace-keepers the Navy.

If you engage in commerce and you have a powerful Navy, you can influence or even control commerce.

Do you see where I'm going? Most wars are about resources. Commerce is about resources. Anywhere you have commerce, you are liable to develop conflict.

I think you're looking at this with a 20th century viewpoint. There doesn't seem like there'd be a lot of physical matter that an advanced civilisation might want to pirate. Perhaps some form of exotic matter, like a black hole, might fit the bill, but that would be particularly hard to steal because everyone could see where you were taking it.

Until you can fabricate matter in your MrFusion6000, material resources in some form or another will continue to be valuable.

Once you CAN fabricate, Einstein tells us you will need a TON of energy to do so. So, even if that day comes, you will still need to acquire energy.

Sure, but even today, raw material resources tend not to be the sort of things criminals target directly. You rarely get thieves trying to steal lumber, or iron ore, for example, because they have a low price-to-weight ratio.

How about copper? We had someone steal it from the crawlspace of a house we rent out.

It's a question of scarcity, platinum, gold, silver, and copper still have value, salt does not.

I think you need to pay more attention.

Lumber: http://www.northfulton.com/Articles-CRIME-c-2011-12-05-19041...

Iron: http://allafrica.com/stories/201112210073.html

Steel: http://www.post-gazette.com/pg/11280/1180364-455.stm

Copper: http://www.reuters.com/article/2009/04/16/idUSLG73912 http://www.guardian.co.uk/business/2011/jun/06/sheffield-cop... http://www.abc.net.au/news/2011-09-06/copper-theft/2873346

He's talking about raw ore, and you're citing articles about concentrated/refined/treated metals and construction lumber.

1. None of those things are strictly raw materials; they've all been refined, cut or treated in some fashion.

2. Coming up with a several examples doesn't show that such thefts aren't rare in comparison to other thefts.

Read TFA, it argues pretty convincingly that there will not be pirates because A) you can't hide in space and B) Any ship is a WMD, so governments will do anything to keep them out of the hands of criminals, and protection rackets would be a far more profitable use for them than raiding commerce.

You could apply the same arguments to why wooden naval combat shouldn't have happened.

You'd think there is nowhere to hide on the ocean- but there is the horizon to hide behind (planets anyone?) and weather (electrical or magnetic storms?) to hinder visibility.

All you need is a few hundred monitoring stations scattered throughout the solar system and you'd have 100% visibility.

There's no phenomenon in space equivalent to planet-side weather that would regularly obscure or inhibit any monitoring system stationed in space.

Pirates are generally noted as coming after privateers. Privateers had plenty of places to hide. Notably privateers with letters of marque against Spanish shipping had British, French and Dutch ports to hide in.

Piracy developed when the pirates could appear easily as privateers. If you didn't piss of your host nation, then you were free to loot the ships you wanted. Then pirates gained enough money and power that they could start their own micronations. Note that privateer ships were often enlisted by the military during wars, so it's safe to assume an assault on a pirate haven was out of the question for the military. Especially when pirate controlled settlements were often cleared by privateers issued letters of marque on condition of clearing the settlement.

I don't see how governments will keep ships out of the hands of criminals when governments show little desire to exploit space, where as corporations do. Corporations will grow very quickly in space, governments won't. Governments are likely to spread via colonies rather than commerce or expansion.

The guy doesn't argue convincingly that there won't be pirates, because his argument should have meant pirates wouldn't have existed in the 1700's. The Spanish knew where the pirates and privateers were running to, but they were well enough armed that you wanted superior numbers. So it was a matter of attacking a solitary ship with more fire power before it could reach a safe port.

Even though Port Royal and Tortuga were known as lawless ports, there was plenty of law there. The Spanish weren't about to invade a port with cannons on its battlements and dozens of privateer and pirate ships docked. Many of these pirate ships were better crewed and equipped than their respective nations military ships. Stede Bonnet had a sloop with 120 men and 16 guns. He was captured when he only had 50 men and was beached in a harbour. Notably the military brought 2 of the same tonnage ship, notably 8 gun vessels which Bonnet's ship had originally been at the start of his life of crime. [Edit: IIRC Rhett had 130 men on his two ships and simply outlasted Stede whose crew surrendered - Stede wanted to blow his ship up rather than surrender]

I'm not sure you've understood the poster's arguments.

The worst a pirate captain could do with a single ship in the 1700s was to sink a few merchant ships.

The worst a pirate captain could do with a spaceship is to destroy an entire continent.

In the 1700s, a pirate captain could hide his ship from government navies, and take merchant ships by surprise.

The location of a spaceship is public knowledge; it cannot take anyone by surprise, and the authorities know exactly where it is.

You can see how there might be a little bit of a difference? There's a considerable incentive for any planet-side government to make sure pirate spaceships don't exist, and there's nowhere the pirate can hide.

This idea that you can't hide in space betrays a lack of imagination. As a rule, ships will operate near objects such as planets, asteroids or nebulae. These objects provide plenty of opportunity for cover and ambushes. There is also the possibility of minefields and other unmanned devices that can easily be shielded from detection. And those are just the things we can realistically grasp with our current technological understanding.

The other point that a rogue ship can wage war against an entire planet is correct, but it's also misleading because the assumption only works if the planet has no defense systems appropriate to the threat. The other argument that ships will be highly regulated because they're dangerous, powerful, and profitable is probably correct but at the same time it's important to remember that being outlawed per se doesn't stop anything. We should know better, because we tried this with drugs, terrorism and copyright violations - all of which are still going on despite the massive amount of resources employed to eradicate them.

Don't forget that motor vehicles are well regulated, dangerous, powerful and profitable. It still doesn't mean dad won't hand the keys to his 17 year old kid and said kid won't try doing 160 and take out a hotel lobby.

We wilfully put aeroplanes in the hands of thousands of pilots. It doesn't stop them coming to work drunk, or falling asleep at the wheel, or heck snapping.

The reason governments won't strictly regulate space ships will be the same reason governments don't strictly regulate driving. It costs too much.

There's just a slight difference between taking out a hotel lobby, and removing an entire continent filled with billions of people off the map.

> As a rule, ships will operate near objects such as planets, asteroids or nebulae. These objects provide plenty of opportunity for cover and ambushes.

Maybe in science fiction.

The main problems you have are:

1. Space is big and mostly empty. A few hundred probes could cover every blindspot in a solar system.

2. Going anywhere requires venting hot gas that's highly visible. Even small ion drives are detectable light minutes away with current technology.

> There is also the possibility of minefields and other unmanned devices that can easily be shielded from detection

Shielded how, exactly?

Also, how are these unmanned devices going to get close to their targets? Space is big, so a ship isn't going to blunder near one by chance. Perhaps if you knew the ship's route ahead of time, but then even a small randomizing factor introduced into the route would prevent that.

> we tried this with drugs, terrorism and copyright violations - all of which are still going on despite the massive amount of resources employed to eradicate them.

Drugs, C4 and digital files are small, easy to hide, and relatively inexpensive.

A spaceship is none of these things.

You've completely missed my point, like took the highway to the next state missed the point.

> The worst a pirate captain could do with a single ship in the 1700s was to sink a few merchant ships.

It wasn't that they sank the ships. Stede Bonnet is noted for capturing around 30 ships in under 2 years, noted in that there's a record of the ships he plundered. The money he took from this went to the ports he traded in.

> The worst a pirate captain could do with a spaceship is to destroy an entire continent.

Depending on the size of the vessel, it's a possibility, but not likely. It's going to be easy to tell if someone's approaching you at ridiculous speed. Also, this means anything you hit them with hits harder. When you're driving at a bullet at the speed of sound, it's definitely going to hurt a lot more. You're not only making yourself more obvious, but more vulnerable.

> In the 1700s, a pirate captain could hide his ship from government navies, and take merchant ships by surprise.

How? Is there some magic cloaking device that prevails the Caribbean ocean? Sorry, but the Navy can't stop drug smugglers by boat today with satellites, radar and whatever else.

They knew where they were going. Do you not think the Spanish knew that Henry Morgan was headed for Tortuga? He didn't have to hide from the British or the French, in fact he ended up an Admiral of the Royal Navy.

They took the merchants by surprise, because the merchants didn't know they were pirates, they thought they were just crossing paths with another merchant ship. Stede Bonnet captured three ships by pretending to trade with merchant ships (notable for their short crews) and rushed them with his 130 men.

> The location of a spaceship is public knowledge; it cannot take anyone by surprise, and the authorities know exactly where it is.

Again, yes and no. Just because you can see everything, doesn't mean you can watch everything. You're assuming one universal government and data sharing between governments or agencies.

Sorry, but it's eventually going to be in one nations best interest to economically harm the other and harbour privateers.

> There's a considerable incentive for any planet-side government to make sure pirate spaceships don't exist, and there's nowhere the pirate can hide.

Earth based governments, maybe. Do you think the colonies are going to turn down building materials for 1/2 the cost? Or protection for harbouring pirates? Anything that increases government revenues will be protected.

Governments will harbour pirates because they have before. The French made piracy rampant by issuing letters of marque simply to damage everyone elses economic ability.

Governments war over limited resources, but they sabotage when there's plentiful resources.

> Depending on the size of the vessel, it's a possibility, but not likely. It's going to be easy to tell if someone's approaching you at ridiculous speed.

So if you a voting citizen of Earth, you'd have complete confidence in your planetary defences, and see no reason at all to send the military after the rogue spaceship that could potentially destroy your country?

Can you imagine a national government saying today, "Yes, we know the terrorist has nuclear bombs, and yes, they're currently in a remote location within strike range of our aircraft, but no, we're not going to take them out because we're 99.9% sure they'd be unable to get those bombs into our country."

> How? Is there some magic cloaking device that prevails the Caribbean ocean?

The atmosphere, the curvature of the earth, primitive communications, and obstructing land masses are all problems 18th century ships had to deal with.

> Sorry, but the Navy can't stop drug smugglers by boat today with satellites, radar and whatever else.

And how many large, hard-to-hide pirate vessels do you see nowadays? How many pirate battleships, or pirate aircraft carriers are there?

Pirate vessels today are small, short-range craft that can be easily hidden, because communication and observation technologies are so much better today than in the 1700s.

> They took the merchants by surprise, because the merchants didn't know they were pirates, they thought they were just crossing paths with another merchant ship.

That trick would only work once. Once the pirate attacked, everyone in the solar system would see them, and their little green icon would permanently change into a little red icon.

> Sorry, but it's eventually going to be in one nations best interest to economically harm the other and harbour privateers.

Why? That doesn't happen today. The US doesn't sponsor pirate battleships to attack the French, for instance.

Privateers made sense in the 1700s, where raw materials still had a lot of worth, and war could be waged between world powers without mutual destruction.

But today, piracy doesn't make economic sense for anyone with any wealth. It's much more profitable to invest than steal.

> Do you think the colonies are going to turn down building materials for 1/2 the cost?

Yes, because everyone will see them doing it, and in a high-technology civilization, raw materials are ultimately not that valuable.

The minute someone says "that's impossible, there is absolutely no way that will happen", someone else begins to devise a way to make the "impossible" scenario/product/achievement possible. Incedentally, the typical HN reader falls into the latter category - so carry on space pirates!

Unless we can effectively teleport, there won't be any interstellar commerce. Everything is too far away.

Interplanetary, maybe, but within our solar system.

There was commerce between the Romans and ancient china that took around 10 years one way. I don't remember what was being traded, except for the silk from china, but it shows that distance and time are not absolute limiters for trading.

Here's a good article about traveling to Alpha Centauri[1]. It posits that it would take 85 years best-case-scenario technology and 81k years using current technology.

Absent the discovery of new physics that allows us to travel through wormholes or something of that ilk, traveling to the other side of the galaxy for a vacation will, sadly, not be happening. Instead long-distance space travel will likely involve putting humans into cryosleep and then waking them up when they reach their destination; hundreds of thousands or millions of years in the future.

[1] http://www.universetoday.com/15403/how-long-would-it-take-to...

Why send humans at all? By that time I'd assume we'd have reasonable AI; just send it along with a bunch of frozen embryos anywhere you please. The AI can incubate and raise the children. It could even terraform the planet until it was habitable. You wouldn't even need to explore; just send out probes willy-nilly. If they never reach a suitable location, then it's no big loss.

A fire-and-forget method of human space colonization is not only far more feasible, but also far more economical.

I think your argument is aiming at the right target, but is using the wrong ammo.

The essay outlines why piracy is not possible (or at least practical) for space commerce. However, it is very plausible that nations will fight over shipping routes and try to destroy each other's freighters and merchant ships. Like you said "Anywhere you have commerce, you are liable to develop conflict." This will be true, but probably only between political states.

True, but probably only until space flight becomes less prohibitively expensive, or the commerce that happens in space becomes more "interesting", to pirates.

Incidentally it was the nations of England, France, Spain and Denmark that caused piracy. Not only did they give charters to captains to give them the right to attack another nations ships, but they harboured them.

The British ports were notorious for this. Spain had control of the gold, so Britain allowed their pirates to attack the gold galleons and haul it back to British ports. The pirates would eventually spend said gold in the port buying items imported from Europe and transferring wealth back to the old world (incidentally this actually faired better for England than it did Spain, as the Spanish gold went into the governments coffers. The stolen gold entered the economy).

I agree, piracy isn't likely to happen just randomly. Without ports harbouring pirates the oceans became clear pretty quickly. The European superpowers didn't want to go to war with each other, but it was still in their own best advantage to sabotage the other.

Remember the majority of 'pirates' were privateers. Many privateer ships were commissioned when their host nation went to war and decommissioned when the war ended. Whenever you see in the movies a pirate ship landing at Port Royal or Tortuga, then they likely had letters of marque from Britain or France against the Spanish, if not they would be real pirates and even then they'd have safe harbour if they didn't piss off the authorities.

Steed Bonnet for instance was a pirate attacking British/any vessels. However he received an official pardon (along with Blackbeard) from his life of crime. However (unlike Blackbeard) he set sail for a Dutch settlement to buy a letter of marque and become a Dutch privateer against the Spanish. However, this didn't happen. He turned to all out piracy very shortly after his departure and when news got back that it was him, then the governor that pardoned him sent the military after him. Then he did the neck hanging dance.

Privateers were even known to reclaim colonies from pirates for being issued letters of marque.

IMO piracy and privateers have a very strong likelihood of occurring. We're already seeing signs that it's going to be companies to exploit space before governments, similar to in the Caribbean. It will only take one nation permitting privateers to operate before all nations and companies of size will be operating privateers. It's the logical step if governments aren't capable of exerting their force more than corporations.

People have been making the argument that war makes no economic sense, and therefore won't happen, since at least 1898:

http://en.wikipedia.org/wiki/Jan_Gotlib_Bloch#Research_and_a...

Sixteen years later, they had the first world war.

It didn't really make much sense, either. Nor the next one.

You probably wouldn't see many fights where you are firing at the resource itself.

No, but if you can control travel to and from the resource, then you can park your forces there, and say, shut off the population's air supply. Better yet, threaten to do so, unless they all get onboard a shuttle.

Plenty of precedent for this tactic. It's been used by labor unions and informal groups of workers for nearly a couple of centuries now.

Maybe someone can weaponize psychological disorders or sociological pathologies this way? It's harder to make a group work well together than it is to make a group that is dysfunctional. Maybe this is already happening?

Sure, but the important part is perfect visibility. You and your opponent know exactly where each other are at all times. If you blockade, you will be a sitting duck for surface to ship weapons. You have to maintain a high velocity to avoid this. The alternative then is to intercept their transports, and even if you do that, you still have to refuel somewhere. (It seems like it might be better sending unmanned missiles to 'intercept' the transports anyway). And the refueling platform or space ship or missile platform will probably be a sitting duck at some point.

I think this is quite likely, you could even engineer people who are simply annoying and send them to cause trouble within in a small mining colony. For example, a person who chews loudly, has bad breath and terrible BO would put a huge strain on a group if you had to share sparse quarters and limited oxygen.

Throw in a sociopath with a strong will to power and you've at least got an 8 part miniseries.

If you are to try a blockade, I'd have to assume you'll bring enough matte with you to start dropping relatively heavy chunks of matter onto anything you see missiles being launched from.

If you are to try a blockade...

I'd accomplish a blockade this way:

Send a squadron of cheap robot ships that are painted in EM-absorbing materials, operate at cryogenic temperatures, communicate only on tight-beam lasers, and beam all of their minuscule waste heat in one direction. These ships would make a final course correction by ejecting cold mass, and take up station near the resource. When an enemy transport comes nearby, I'd send a command to activate one of my robot ships and have it launch a missile. Heck, since at that point it would be disposable, I'd have it spin-up to high-temp torchship mode and have it be the missile.

The enemy won't know how many of these things I have. However, the real purpose would be to get them to react and maneuver resources in place to detect my hidden ships, so that I could detect the energies of those maneuvers to set up the real attack.

Stealth won't be important, my ass!

Why are you always supposing that ships would be firing at valuable planets, then debunking that? Just extend the idea of a nation's airspace to a planet's "spacespace." Establishing space supremacy around a planet would obviously be a useful military tactic. You can stop extraplanetary supplies and commerce (think the blockade from Star Wars) and eventually take over a valuable planet by starving them out (assuming that the planet relies on space travel for a significant part of its economy, which is pretty much te assumption of this whole debate). That planet in turn will want its own space fleet to protect its spacespace. When the two forces meet, you have space battles. It seems simple to me.

Well, let's say I want to gather minerals from an asteroid.

My primary defense would probably be to paste a big honking weapon on the asteroid and shoot anyone who wants to take over my valuable mining facility.

If I put my defenses on something next to my planet, I'm an idiot. If he destroys my defenses, I want him to also have a high chance of destroying whatever he's attacking me for.

So I build a big weapon as well as commensurate defenses. It isn't unimaginable that the destruction created by future weapons in order to penetrate future defenses would be immense. High velocity and mass will be the only way to do this... mostly in order to prevent deflection/destruction. You have accelerated a projectile to significant fraction of the speed of light in order to get it through the target's point defenses (think missile defense shield). Anything that can penetrate the missile defense system will have extreme destructive force, without needing a warhead.

Generally the point of a blockade/siege is to starve out the opponent so that you can eventually take whatever they are squatting on. Your opponent has a big weapon that you don't want to shoot at (you aren't looking to destroy what you are fighting over). Your blockade would be a sitting duck unless you destroy the weapon, and you significantly reduce the value of the planet/asteroid if you destroy the weapon.

In addition he also has perfect visibility due to the empty nature of space... he can see and shoot at you whenever he wants. If you intercept his transports, he shoots at you. If you stop to refuel, he shoots at you. If you start taking out his less valuable assets, he shoots at you. He can shoot your other assets too. Your space armada has to refuel at a fixed point in space... likely visible to his weapon.

If there were a fight, it would likely be very short and involve both sides having their logistical assets completely annihilated... Which ultimately would defeat the purpose of attacking in the first place.

Two things: First, I don't think that huge kinetic weapons would be the ideal choice for this kind of combat. If I'm attacking an asteroid with a huge ass gun on it, I'd first like to have some type of EMP type weapon developed to simply shut down the tracking/aiming/power supply of the asteroid's defenses. Just the threat of an attack like that from orbit would probably be enough, as it would likely shut down life support on the rock as well.

Secondly, assuming that such a weapon isn't developed, depending on what you're mining, it seems likely enough that it won't matter what shape the asteroid is in. For mining solid materials, it would probably be best just to blow these asteroids into manageable pieces and send the whole lot through your enormous space processing plants for extraction and refinement. In this case, you'd need space fleets to protect your "planet crackers" and to protect your processing vessels from other companies, pirates, etc.

This essay isn't all that realistic. I found this one [1] to have a far more realistic view of what space war would look like.

Tl;dr: it's much cheaper and much more effective to lob comets at your enemy's homeworld than it is to fight with ships.

[1] http://www.gwern.net/Colder%20Wars

Ender's game spoiler alert! Hope it doesn't ruin it for anyone else... (grumble.)

Anyway, how the heck does one lob a comet? If throwing one was so easy, why wouldn't they just throw it right back at you?

Well, both gwern's essay and the essay linked by OP assume that both sides have ships capable of interstellar travel. In gwern's case the idea is to not bother with the ship; just bolt an interstellar drive to a comet and point it at the enemy's homeworld.

As for them throwing comets back at you, that is addressed in the essay. In short, there is nothing stopping them from throwing comets back. Space war will resemble the Cold War much more than any active engagement. Mutually assured destruction will be the overriding doctrine.

Do you really need a spoiler alert on a young-adult novel that has been out for 26 years?

It's not like they stopped making young adults 26 years ago.

Physics. Attacker gets arbitrary mass (reactant, etc) and time to accelerate. Defender needs same mass/time to decelerate... after discovering the attack.

Note that you could literally prep an attack for millennia which would be discovered a matter of hours prior to ending a civilization.

Physics makes for sucky narratives. Good thing it also makes for a vast, dead, boring universe.

I don't think you would try to slow down approaching meteorites to zero speed, only deflect them a little so that they miss the planet. The further away you catch it, the less energy it takes (I assume, didn't do the maths).

Debatable. On the one hand, the farther the projectile is from the planet, the less it needs to be deflected. On the other hand, you have to expend energy to get to the damn thing in the first place.

I suppose the survival of your species renders moot most energy concerns though.

It depends on the momentum of the asteroid. If I've accelerated an asteroid up to .5c, then even if you discover the attack years ahead of time you might still not have the energy to deflect the asteroid by enough to save your planet.

You also have to remember that the attacker can launch multiple simultaneous asteroids. You might have enough nukes to deflect one asteroid. Do you have enough to deflect ten? A hundred?

If you can accelerate an asteroid up to .5c, you have harnessed energy resources to power the earth for a gazillion years. You would be so rich that you dont need to be a warlord. You could become ... a banker.

Actually, at .5c from the Kuiper belt, the warning time is only 30 hours or so and the momentum is such that deflection is impossible. I'm too lazy to do the math but the collision would be spectacular.

Momentum doesn't really work this way. The only things that change the difficulty of deflecting something are it's mass, and the remaining time to impact.

Having a lot of momentum doesn't change how much force is required to give something a given acceleration until relativistic effects start to matter.

(I guess distance also makes it harder, because you need to travel further to start deflection, but that's not really a momentum thing)

Well, since you're going to skirt around how the acceleration actually happens, I'm just going to counter with: The defender also has arbitrary time to defend. Couldn't you "store up" a defense over time somehow? Maybe have a counter-projectile orbiting really fast that can be brought out of orbit to hit the incoming one? Or, I know we don't have energy shields, but with the amount of assumption going on in this whole article, I may as well assume we do ...

"orbiting really fast"

That is an oxymoron. You are either orbiting or going "really fast" but you can not be doing both. (In the context in question single-digit miles per second is not "really fast", it's just the cover charge.) You can pour arbitrary amounts of energy into a kinetic kill projectile, and there is no known reasonable way of defending against such a thing except to not be where it hits.

Just as people worry about nuclear weapons and biological weapons, we get planet-killing kinetic projectiles rather earlier than we get anything else useful from space. In fact if we put our minds to it, and were willing to be patient, we could probably do it today. The same tech we're looking at to divert existing planet killing asteroids can just as easily be turned to tweaking one of their existing orbits towards us instead of away.

The physics on storing kinetic energy like that just don't work.

One intriguing possibility I thought of is the possibility of creating a black hole[1] in the path of the projectile. I have no idea how the energy calculations work for creating a black hole, and what exactly happens to one if a large mass travelling at high speed hits it - I'm guessing if the black hole was small it would just slice the object in half. If it was big enough to "swallow" the object then I don't know what happens - if I'm reading [2] correctly its mass-energy increases, but what that means in practical terms I'm not sure.

Of course, the issue with this plan is before you had a fast moving massive object targeted at planet, but now you have a black hole nearby.

[1] http://news.sciencemag.org/sciencenow/2010/01/22-01.html

[2] http://www.upscale.utoronto.ca/PVB/Harrison/BlackHoleThermo/...

Spoils Ender's Game? Bummer. I recommend you read it anyway.

I postered a comment on the essay, I'll repost it here:

You assume the interstellar species will be living on a planet. What if they hollowed out their planet of resources long ago and now live in a cloud of asteroids instead? Asteroids are hollowed out as giant fortresses in space, and a bio dome sphere thingy built inside. As they are living in an asteroid cloud, to prevent impact they would have to attach thrusters to each asteroid they live on to dodge other asteroids.

So the asteroid from kuiper belt attack won't work... but what if the asteroid was launched at close to speed of light? 1. That would take a very big amount of energy. 2. They would've had to carry the energy to the kuiper belt. 3. They would've been noticed and a fleet would've sent in to capture it before the asteroid was launched.

What about the nuclear bomb? Well they live deep in the asteroid, it'll protect at least against some nuclear hits. If one asteroid blows up there are still 499 others. Still it would be great to prevent the loss of sentient life... Also what happens if 500 nukes were launched at each asteroid? I've got no answer to that.

I do wonder if there could be a device that would force nuclear explosives to be triggered prematurely, lets say, 2km away. That would be sufficient to protect the asteroid.

What about a shotgun approach? Take a comet, accelerate it up to a significant fraction of lightspeed (after all, you you have lightyears in which to do so), and trigger a bomb in the comet to blow it apart into a few smaller pieces, each traveling at a significant fraction of c. Rinse and repeat.

That's probably the best suggestion here. Not as easy to deflect something like that.

I've made another reply at the site:

So the invading force goes into the Oort cloud, picks a chunky rock, attaches a giant thruster to it and begins accelerating it towards c. A day later, the speed of the rock has reached 0.5c.

Hours later, a defending fleet arrives, shoots and kills all the invading bds. The rock however, continues at 0.5c even though the thruster and guidance systems were destroyed. It reaches the asteroid cluster, and hits... nothing. It keeps going to the other side of the solar system, and as its speed was so high, exits orbit.

Accelerating a giant rock to c takes throwing out alot* of gas. The asteroid based civilisation, to prevent random impacts with random asteroids, would've been tracking every object in the belt. One of the rocks suddenly accelerates, I think it will be picked up.

Also, when the asteroid was accelerating, its direction would've been picked up. Once accelerated to c, it will still take hours to arrive at the designated target. The home asteroids simply have to maneuvre away from an intercept course. And no, guidance systems on the accelerated rock won't help. It's travelling at c, and by the time the system finds out the target has moved away, the asteroid would've missed it. Unless the asteroid have 100% maneuverability, and energy to change course whenever, however it likes. But if the asteroid can do that, any asteroid can do that. ;)

So your only option is accelerating the rock from the next system onwards. It will now take years for the asteroid to arrive. To reduce the probability of a successful attack, just have a "random thruster day" every 30 days where all the home asteroids just move randomly to different locations. By the time the enemy asteroid arrives the location of all the home asteroids would've been different. The probability of hitting anything worth hitting will be very low. Even if you have 1000 incoming asteroids.

Also you're assuming you won't get picked up accelerating an asteroid to c in the next system; Remember, asteroids have no atmosphere and 100% visibility. You might miss 1, but 1000? I'd doubt it. if 1000 asteroids are really incoming then you just make every day random thruster day. ;) They have so much energy, you should too.

Generally I agree with this analysis, but I think there is an attack that would work:

Strap small N-bombs (or conventional bombs?) to as many as asteroids as possible, launch them at the target area, and then blow them up ~500,000km away. Suddenly you have thousands (millions?) of significant chunks of rock travelling at 0.5c and spreading out. If you got the explosion point right and had enough asteroids you could cover a reasonable amount of the likely positions, even based on random movements.

It's unlikely to destroy an entire asteroid-belt based civilization, but wouldn't be trivial to evade either.

The fighting methods in that essay still require ships (to sneak up into e.g. Kuiper's Belt). In any case, a big, dumb projectile can have its course changed with much less energy than required to fire it. The bigger it is, the earlier it will be detected; and the faster it goes, the smaller the angular deflection needed to miss its target.

While it is true that it should be easy to deflect, it is only easy to deflect if you can detect it. The essay assumes that the projectiles would be pushed to a significant fraction of the speed of light. At that speed there is no time to launch any type of deflection.

The energy required to accelerate a big object to even half the speed of light is prohibitive. Even if the process was feasible, it would be a vast cosmic event bound to emit some radiation, which would still arrive much sooner than the object itself.

Well you don't have to accelerate it all at once. Remember, this is space war, and we're playing for keeps. Spending a millennium to accelerate a rock up to .5c might be worth the trouble.

If you take longer to accelerate it, that just increases the probability of detection by other means. It still doesn't change the argument that it should be much cheaper for the defender to detect and deflect your projectile than it was for you to launch it in the first place. Not to mention that an unmapped interstellar gas cloud, or an undetectable asteroid, is all it takes to deflect the projectile a few millionths of an arcsecond and make it miss its target.

He addresses that in the next paragraph:

If that’s not bad enough, one could envision flinging appropriate small moons or large asteroids from other solar systems. Why not? Boosting a large body to fractional c velocities and aiming it at a far away planet isn’t inherently any more absurd than building a ship and boosting it to fractional c. The motion of stellar bodies is famously predictable out for many centuries. The body could guide itself: add some small motors, and it could even correct for small errors in prediction. It would be the ultimate fire-and-forget weapon of mass destruction.

So you don't have to sneak up at all. You just need to have a solar system with a Kuiper Belt, and you've got all the arsenal you need. In fact, launch attacks from remote solar systems is preferable, since it gives your bullets more time accelerate before becoming visible to the enemy. They may have enough enough energy to stop an asteroid traveling at .5c. Do they have enough energy to stop one traveling at .9c?

Reaching even a small proportion of the speed of light requires prohibitively high amounts of energy. Let's consider the energy required to accelerate Haley's Comet (relatively small at 2.2e14 kg) to half the speed of light (v = c/2):

E = mc^2 / sqrt(1 - v^2 / c^2) ~= 1.15 mc^2 = 1.15 * 2.2e14 kg * (3e8 m/s)^2 = 22.77e30 J

For comparison, the Earth absorbs each year about 3.85e24 J of solar energy, so we're talking about six million years of total incoming solar.

Assuming two societies with similar technology, it will cost vastly less energy for the defender to give the object a small nudge than it cost the attacker to propel it in the first place. The attacker would do much better to invest into a fleet of ships that can respond to contingencies and adapt to the defender's response.

Your math is wrong. Accelerate Haley's Comet to half C in how much time?

One of my favorite "ohh, that's interesting" facts about space combat, is that a kinetic kill weapon (ie, .9c rock) being shot at you. By the time you see it, it's already 9/10s the way to you...

The "bugs" in Paul Verhoeven's "Starship Troopers" make ample use of this idea: http://www.youtube.com/watch?v=x7-PQIuWwLo

It seems you and Heinlein are of like mind; remember Mycroft's conclusion in The Moon is a Harsh Mistress that the best way to fight the Earthen forces was to "throw rocks at them"?

This is why Carl Sagan argued against projects like Spaceguard that purported to defend against rogue comets or asteroids. He felt that the risk of a space collision was much smaller than the threat of humans turning the technology around to hurl asteroids at our enemies.

It was definitely an interesting read, however, I feel that fundamentally, for humans to reach the point where space combat is even feasible we will have solved so many more important problems that there won't be a need for fighting in the cosmos. Earth, in general, is at peace. We are largely struggling against terrorism, radical groups, and internal genocide rather than full scale, nation-on-nation wars.

No two democracies have gone to war, ever, and that's an important indicator of our future. Don't get me wrong, we have A TON of human rights, poverty, and equality problems, but things are rapidly improving directly proportional to our technical capabilities.

By the time we can even construct two ships capable of having a realistic fight in space we're more likely to send them exploring rather than duke it out. All current governments even capable of dreaming of getting in to space work together on the problem, sharing resources and knowledge.

To recap, we'll never go to war in space. I also doubt any other intelligent life with the capabilities to do so will need to attack us because they've solved any problems requiring them to do so.

We may still do it for sport.

> No two democracies have gone to war, ever

That stirs up a whole new thing, detailed here: http://users.rcn.com/mwhite28/demowar.htm

That was almost as good a read as the main post :)

>No two democracies have gone to war, ever,

India and Pakistan?

Against space piracy:

First, it requires that FTL ships be cheap enough that criminals can acquire them. This is another area in which the analogy between the age of sail and the space age breaks down. Sailing ships were skill-intensive but materially cheap. You had to have people with the right skills, but once you did all you needed was wood, rope, and cloth. But spacecraft are going to follow a post-industrial revolution paradigm of being materially expensive as well as skill-intensive. They are likely to require sophisticated, precision-manufactured components and expensive fuels like helium 3, fissionables, or antimatter. Imagine Captain Jack Sparrow commanding a nuclear-powered aircraft carrier and you’ll get an idea of the kind of difference we’re talking about.

If technological trends continue, the degree of technology available to the average citizen and the average criminal will continue to increase. As an individual, I have access to more media distribution than Queen Elizabeth could even imagine. As an individual, I can build a device like a CNC machine or a 3D printer from off the shelf parts.

Skillfully crafted wood, rope, and cloth would seem like miracle items to someone from the stone age. A CNC laser cutter would represent miraculous technological savvy and princely embodied wealth to someone from the 1400's. The equivalent to an Orion ship might well be within the rech of rogue elements of the late 21st century.

That said, space piracy probably won't happen, or at least won't resemble piracy from old movies in the least, but the technology being out of reach won't be the reason why.

Agreed. Piracy denotes the theft of goods or money. When you can print goods, money is worthless. Your soul resources become matter and energy, and most matter is easy to come by.

Piracy would likely extend solely to the theft of energy resources. Similarly, so would war but on a bigger scale.

Piracy of goods would only extend to things not easily replicable by the present technology, or not easily replicable on many colonies. Even then, you're looking more at the theft of raw materials or for material value. Piracy would likely resemble robbing armoured vans today than any kind of piracy we've seen before, but they'd likely be trying to get precious metals or power like uranium.

most matter is easy to come by

Endless wars over oil, rare earth metals in Africa and the ever increasing price of iron ore would tend to indicate you might be wrong about that.

Just because a single 3D printer won't use much won't magically make resource constraints disappear.

I guess he's imagining some cheap way to rearrange subatomic particles.

The logical steps in 3D printing is to increase the number of molecules the printer can print with. There's almost an infinite number of molecules you have to deal with, so it's a very logical step that once 3D printing becomes a commercial endeavour then there'll be quick steps made towards an atomic printer.

91 regularly occurring natural elements is a much shorter order than tens of thousands of common molecules. Considering there are over forty simple hydrocarbons and molecular printers start looking bulky, granted you might only ever use a maximum of 5 hydrocarbons, but that day you need a 6th you'll be cursing your shitty base model printer.

As I said, piracy will eventually extend to the theft of energy or raw matter.

Carbon, silicone and iron are easy to come by in space. Actually, given that olivine may be a common material in asteroids you're looking at abundant magnesium, iron, silicone and oxygen right there. However things like rare earth metals may be less easy to come by and if 3D printing jumps to molecular printing, then there'll be ships carrying pure metals as goods. Consider Neodymium cost averages $350/kg, a ship hauling it out to Neptune will be worth a lot of money stolen. Especially when the pirates would be selling for <$300/kg.

If piracy happens over raw materials, eventually so will war even if it's just to stop the pirates. However there'll be asteroids found with thousands of tonnes of easily mineable rare metals, and then we'll see space battles.

When commanding the high energy technology necessary to transmute elements in useful quantities becomes widespread, then all resource contention is going to be about energy. Those with access to more energy will be more powerful. People will covet the bottoms of steep gravity wells and proximity to suns and black holes.

Others will value their freedom more and try to get by with less, and will avoid such political and literal hot spots. The vastness of space will be their most valuable resource. They may well be the final nomads and the last vestiges of humanity.

Here's a thought I've had in the past after encountering a document of this type: Stealth in space is trivial is what you are trying to keep hidden doesn't need to accelerate, support human life or do anything much that generates significant heat, especially if it can stay far away from what it is hiding from. Space is big and hard to hide things in, but it is full of all kinds of smallish debris in the vicinity of a solar system. If you have something of about the right size, orbit, albedo, radar reflectivity and temperature, it ought to be hard to distinguish it from a stray bit of rock or ice too small for anyone to have paid attention to it in the past.

Bearing this in mind, suppose that you built a small, camouflaged satellite which would just sit there at ambient temperature until it received instructions, upon which it would point itself at a given patch of sky, do the finest bits of the aiming using its own passive sensors and then fire a nuclear bomb-pumped x-ray laser at whatever has the misfortune to be there. With something like this, one could probably swat any reasonable craft out of the sky before it had time to respond. You could perhaps also use such things offensively by putting them on orbits that will take them within their effective range of whatever you want them to shoot, though they would stand out a bit more that way.

The only real countermeasure to these I can think of would be to move your spacecraft rapidly back and forth at all times, which is probably infeasible given the amount of reaction mass it would take.

I'm not sure what the implications of all of this are, but I suspect they would be interesting.

It's an interesting topic for discussion, but the writer makes lots of "realistic" assumptions whil ignoring many others. Assuming this level of "realism" -- I.e. no unforeseen technologies -- we basically don't get enormously high delta-v for most kinds of useful ship, so the very high sustained accelerations (e.g. 4G) aren't going to happen. The discussion of perfect intelligence is good but fails to mention that most plausible spacecraft would be detectable at enormous ranges even with their engines OFF. Clearly almost everything will be automated and networked.

I think the writer starts out with the a priori assumption that there will be spaceships with a crew at one end and an engine at the other and works from there. I suspect you'll just have a swarm of networked drones. Why put so many eggs in one basket?

(We're already seeing this approach being experimented with on nuclear hunter killer subs, where firing at an enemy gives away your position, and giving your position away gets you killed -- the US Navy has been working on submarines tha launch drone firing platforms.)

If you're interested in "realistic" (meaning: no FTL) space battles read Alastair Reynolds' Redemption Ark (and read Revelation Space and Chasm City before that).

It includes a chase between star systems that goes on for years and "close" (ie within a few light-seconds) combat that involves a lot of interpolation of enemy position, movement and actions.

Personally I still have serious doubts about the viability of any kind of prolonged manned presence in space. Its simply too expensive and the distances involved in interstellar travel are so vast that even perfect mass to energy transformation would make the process prohibitive in terms of cost and time.

But it's fun to muse about.

I assumed that most of the proposed space battles in question would be between human factions relatively close together (certainly within the Solar system).

Why would space war ships be manned when we're already flying unmanned vehicles on earth? I think we've touched on a reality of intelligent species coexisting in the universe. Space war would consist of staying hidden and probably nothing else.

Plus, certainly people would be fighting over the planets or the technology (or maybe the amulet of Endor) so simply throwing comets and obliterating things wouldn't make much sense except maybe defensively or to help with a gennocide.

Terrestrial battles to take over usable land would probably continue to be the name of the game. Followed with setting up tonnes of drones and sensors for defense.

Speed of light delay could be critical in space battles, especially when you consider that it goes both ways (sensor readings -> brain : decision making -> control signal). The real question is how smart you can make computers, if you can't make them as smart as a human then you need to have a meat-brain somewhere in the middle of the battle. If you can make them that smart then that opens up a whole host of questions on sentience and ethics.

Edit: Keep in mind that your manned "ship" might still be thousands or millions of kilometers away from the enemy and controlling a vast array of computerized drones. But when weapons are zipping around at 10s, 100s, or even 1000s of km/s the scope of the battlefield changes dramatically. You can be remotely operating missiles that are farther away than the moon is from the Earth and still be in the thick of it.

I don't know if as smart as would be valuable against as low powered as. A computer would make decisions instantly, take much less resources, would die less easily, wouldn't get bored, wouldn't forget it's mission, would feel no sympathy, could travel farther, could stay in operation longer, could tactically self destruct without hesitation, would take no salary.

But that being said, I honestly can't think of a reason to ever have a space battle. You either want to blow up a planet or not. If so, you do it from an large distance with a humongous rock. If not, you land on the planet, or fly around their atmosphere and kill them the old fashioned way.

Maybe defensively you chase down an attacker to prevent future attacks? But then all you have is guided missiles and the speed of their ships. Not really a battle.

What I guess I'm saying is I can't ever see there being an attack position other than lets wait until there are no rocks in-between us and them.

We already have nuclear weapons on Earth, yet wars still happen. Space is big, incredibly so. And once there are people and industrial infrastructure sprinkled throughout it armed conflicts will probably be inevitable.

>Why would space war ships be manned when we're already flying unmanned vehicles on earth

Because the longest distance on Earth is only about 0.07 light-seconds.

And why do you think they would be remote controlled?

If you put a smart enough brain inside it, you could just upload a copy of the crew (assuming you can digitize and run human minds, of course, something that seems easier than interstellar travel). This way, the ship would not be limited by its crew. The crews responses would also only be limited by available processing speed. And, instead of lifeboats, you could transmit the crew states. In fact, you could do that regularly across the fleet for synchronization and backup purposes.

And, from the inside, it could look exactly like a Constitution class federation starship. People younger than me would prefer a Galaxy class. I, myself, am in doubt between the Constitution and the Heart of Gold. Or a big bridge like the original Battlestar Galactica. The computer could easily generate a lot of red-shirts for added drama during battles.

"Unmanned" can mean many things, but considering the OP's quote "when we're already flying unmanned vehicles on earth", he clearly meant remote control.

I meant something like a combo of AI with orders beamed every now and then.

I admit to skimming this, but there are a couple of things I see wrong with this.

1. You can see a spaceship from the next solar system for sure. But it would take years for you to see it.

2. I doubt the future of combat will involve humans. I envision giant fleets of spaceships that are too big for humans to control. Thus, I forsee space combat as being driven by complex algorithms.

I imagine that the individual ships themselves will also be very small. In fact, if a fleet is big enough, the communications gap becomes a problem - space battles may end up looking like a fight between two ant colonies, with small independent ships working together as a swarm, without any central guidance.

You never know. I'm sure you could have a more "distributed leadership". I'm sure this could be accomplished with a clever enough application of paxos.

I agree with the author in that it's unlikely we'll get a Star Trek scenario where a single ship can continue taking hits without much consequence. In all likelihood the first hit a spacecraft takes will destroy it.

In that environment you really want as many small ships as possible - large capital ships really work against you. Any centralized command system would also be trivially easy to destroy by concentrating fire on the command ship.

A swarm of distributed ships seems much more viable in this system.

Right, but with Paxos, you could elect a new leader as soon as the old one is destroyed.

As to 1: It would take years for the light to get there, it would also take several MORE years for the ship to actually get there. The important take away is distance can't be used to hide, there is no "Oh they won't notice us we're still outside the orbit of Pluto."

How can that be? Space is big, we cannot even properly comprehend how big it is. I'm talking just in our immediate vicinity. If I took, say, three of the world's largest ships, put them together to form one ship and then placed it in a random spot somewhere within the orbit of Pluto; how long would it take you to find it? Keep in mind I'm not talking within the orbital plane, I'm saying within the sphere of the solar system.

Unless someone is watching 100% of the sky for even the slightest miniscule changes, I imagine you could get mighty close (granted, close is Pluto) without being detected.

Isn't most of the information we have about newly discovered far away objects is how they interacted with other known far away objects?

But, of course, there's the given that if we've advanced far enough to engage in space combat then we've likely created technology to help in detection.

Well yes, there are quite a few telescopes that constantly scan the sky for tiny changes. And it's not just the size of the ship, but the burning fuel from its engines as it navigates near our solar system.

Good replies, but I'll combine my thoughts here.

Ships CAN be bright, we have the tech now to make them dark.

True, burning fuel is a big problem. Especially if they were traveling rather fast towards us and they flipped over to reverse thrust to slow down. But what if you don't burn fuel as a means of propulsion?

I'm going with the assumption if that if someone wished to do something bad, say invading a neighboring solar system, they would take precautions in being detected.

The point was never that the ships themselves can be bright, it was that the radiation is easily visible.

The article was also operating within the realm of theoretically available technology. There are very few propulsion systems that don't emit hot matter out the back (like solar sails) and the article addressed them suitably.

It's two things basically:

-You can do a full survey in about 5 hours with one telescope these days.

-Ships are very bright, don't look anything like stars and CCDs are very sensitive.

http://www.projectrho.com/rocket/spacewardetect.php has a good break down.

I've been trying to get a sense of how effective these scans are. Asteroid 2005 YU55 was discovered 28 December 2005. It's about 400m in width, which is the length of the biggest vessel we have. When it was discovered, it was 0.8AU from the Earth, and its orbit is inside that of Mars.

This tells me that 6 years ago we did not know all of the +300m asteroids within the orbit of Mars. How much better are we now? I read the page you linked to, but that didn't list actual numbers based on asteroid searches.

There's an estimated 4,000,000 asteroids in the solar system of size 300m or larger. I sincerely doubt that a telescope survey of 5 hours finds 1 million+ asteroids each night, otherwise that number would be pinned down a lot better. (It can't find all 4 million because at 5 hours there's still substantial portions of the sky unseen.)

Asteroids don't pump out waste heat. Things get a lot more obvious when heat differentials are big.

I was commenting on Talmand's scenario; take "three of the world's largest ships, put them together to form one ship and then placed it in a random spot somewhere within the orbit of Pluto; how long would it take you to find it?"

Using the formula in the "Refrigeration" section of the page linked to by Avshalom, the "maximum range a ship running silent with engines shut down" (assuming diameter = 500 m and temperature = 290K is about 500 million km, or about 3.3 AU. That's well within the orbital radius of Jupiter.

That's assuming the entire asteroid is at 290K. Pluto averages about 40 AU out, given a 0.056% chance that a room-temperature asteroid would be detectable.

I'm also uncertain about the reasoning in the page linked to by Avshalom. I think that assumes a 3K background, and I think you also think there's a big heat differential. However, the average temperature of the moon is something like -25C, and if an asteroid were closer to the sun, then the difference in surface temperature between an internally heated vs. sun heated asteroid is well within the errors in measuring the physical properties of the asteroid.

You can even work it out for yourself, using the equation at http://en.wikipedia.org/wiki/Standard_asteroid_physical_char... . I worked it out to:

  166C at Mercury orbit: http://www.google.com/search?&q=(((1-0.1)+*+(3.827E26+watts)+%2F+(0.9+*+Stefan-Boltzmann+constant+*+16+*+pi+*+(0.3+*+150000000+km)**2)))+**+(1%2F4)

  90C at Venus orbit: http://www.google.com/search?q=(((1-0.1)+*+(3.827E26+watts)+%2F+(0.9+*+Stefan-Boltzmann+constant+*+16+*+pi+*+(0.6+*+150000000+km)**2)))+**+(1%2F4)

  5C at Earth orbit: http://www.google.com/search?q=(((1-0.1)+*+(3.827E26+watts)+%2F+(0.9+*+Stefan-Boltzmann+constant+*+16+*+pi+*+(1.0+*+150000000+km)**2)))+**+(1%2F4)

(The values for albedo and emissivity are not well known, so there is a wide error range in this calculation.)

Still, that's enough to show that the heat differentials inside of the Earth's orbit are not that big.

You are using averages where the min and max are extremely wide apart. For example, the Moon is not actually at -25C, it is either +130C or -110C (or transiting between). We know the time when those temps occur, so we can look for other objects not at those temps at that time. Same goes for the other objects.

I am definitely using averages because if you have an ship which is 300+ meters across then you can leave the top few meters for insulation, so the surface of your ship has the expected extreme temperature ranges.

I should restate what I said: instead of "that's assuming the entire asteroid is at 290K", I mean, "except the insulation layer", which you need anyway to keep the near-surface area livable.

If you need 20 meters for that, then your living volume is 21 million cubic meters, or a reduction of about 20%.

That's not to say that there's no contribution. More that I believe the calculations from that linked-to page ignore the difficulties of differentiating between the internal heat (cooled through black-body radiation) from surface heat from the sun.

For example, from Stefan-Boltman, cooling goes as T * * 4, which means if you have a cooling radiator on the sun-side which is at 150C, or 20C above "normal", then it's about 6 times more effective than a -90C radiator on the cold side. I suspect it's easier to stop the 20C delta on the cold side than the warm side.

I'm in the US, how exactly would I complete my survey with one telescope over five hours if I wanted to see the full sky of, say, Australia?

Well, now we're getting into the theoretical issues. For instance, if we develop wormhole technology, the ship could very well be there before the enemy can see it.

Otherwise, I just don't see interstellar space warfare as being that practical if it takes years to launch an attack.

If I could create wormholes at will, I wouldn't traverse the wormhole with the whole ship - just the bombs would suffice.

Why waste bombs. If you can create wormholes at arbitrary locations just teleport piece of a star into a planet.

If I could position both ends arbitrarily, a better approach would be to connect the planetary core with a black hole.

If you can create wormholes at will, you don't need bombs. Put one end of the wormhole in the target and the other in the center of the sun.

Any guesstimates on how large the wormhole would need to be for it to be a doomsday device? Two estimates, one for a wormhole on the surface of our sun, and the other for its core. I'll try to post my results sometime later.

What about a neutron star? It's probably too exotic to consider how a wormhole would interact with a black hole.

That makes little sense. Do I assume that use of a wormhole circumvents thermodynamics? After all, the sun is in the bottom of a rather large gravity well. It's about 900 MJ/kg from the sun to earth (I think that's measured from the core). A megaton explosion is 4.184 petajoules, so if you could move 5,000 kg from the sun to the earth then it's the same amount of energy you would need to set off a megaton explosion.

I don't know how much density is in a 5,000 kg chunk of the sun.

my takeaway: there will be no space battles, because whichever side has more money will always have vastly superior weapons, and they will take what they want. violence will happen in key strategic plays, like political assassinations. it's not like today's earth-combat where we're all mostly equal and everyone has time to launch their nukes and we all die. this is all assuming that one side doesn't simply exterminate the other like a termite infestation.

Still only part way through and though I don't entirely agree with all the conclusions the thought experiment is proving to be fun.

This however is my favourite point so far as I had never really thought about it this way when watching popularized SciFi.

Another thing about motion in space is that changing your ship’s orientation does nothing to your speed and vector unless it is accompanied by firing your main engine, because there is no friction. This means that all those space dogfights where one fighter gets behind the other and the other one has to try and shake it like in air combat are very unrealistic. There’s no comprehensible reason why the pursued pilot can’t just turn his fighter around and blast the bugger.

Buck Rogers in the 25th Century TV series has just been ruined for me. Wait, no, it still had Wilma Deering, so all is not lost.

AFAIR they did that maneuver on Battlestar Galactica a few times. But still, it's a good point.

Babylon 5 did this a lot as well.

I don't think space combat is even going to happen. Any combatant with the necessary wealth and technology to develop any space-combat capability is going to have significant terrestrial interests and nuclear weapons already, at which point they're already subject to MAD and won't engage in direct combat anyway. At the very minimum, you would need economically and politically independent Moon/Mars colonies, and even they would be so dependent upon Earth trade that they would either not want to start a war or, even if they did, would have Earthbound allies who are significantly more vulnerable than they are, and no less essential to their survival.

The closest we'll ever get is probably the development of ASAT weapons, and even those aren't likely to see much use.

> Any combatant with the necessary wealth and technology to develop any space-combat capability is going to have significant terrestrial interests

Imagine a colony that long ago severed its ties with Earth (or whatever other terrestrial body they started from). Living off comets and asteroids seems entirely feasible and it's a much harder to attack/easier to defend set up.

Complete economic isolation from the earth seems very unlikely, at the very least because it wouldn't actually benefit anyone.

If the outer solar system dwellers become self-sufficient, they would have no need to go down the gravity well of the Sun to have commerce with earthlings. The further out those colonies are, the lesser their contact with Earth will be. If they live off the Oort cloud, the would be about one light year away from Earth and it's very hard to imagine a shared culture with such a communication lag.

Why, exactly, would people dwell in the Oort cloud? The idea of having an isolated, self-sufficient colony in the Oort cloud seems like an even poorer version of North Korea, except you'd have to ship all the people out there.

There's no good analogy with colonialism on Earth, because most of that involved getting very very rich by trading with the mother country, and if there's anything to be won, economically, from the moon or the astroid belt or even the Oort cloud, it'll be from Earth trade. As far out as the Oort cloud, you'd be better off sending robots than human colonists for the very same reasons you point out.

What if the people want the exile? Provided fabrication technology is advanced enough to provide for material comfort, what is the difference between living on a planetary surface or living on a very comfortable habitat? What if you don't like Earth laws?

That same fabrication technology would negate the traditional colonial model. There would be very little need to move physical goods between worlds.

Imagine having a million times more space and material resources than you currently have on Earth now. While the mass on the Oort cloud is a fraction of the mass of the Earth, it's still a lot of stuff.

Alright, let's go with that scenario for the sake of argument. What would be the casus belli?

If it's something like rare elements available only in the Oort cloud, the traditional colonial model would apply and the overwhelming interest in the Oort cloud would be in those very rare elements and not as some sort of refuge. Your Oort cloud pilgrims would have to be fiercely protective of their rare elements and to have gotten there first before the rare-element prospectors. The Oort cloud would have to be not big enough to satisfy both groups of people, and the Oort pilgrims would have to be stubborn enough not to move their replicator-colony to the Kuiper belt or elsewhere.

At that point, you can start to reasonably speculate: you have clear objectives on both sides at the very least. It becomes very hard to predict what would happen because we've stipulated so many counterfactuals that everything we know would be obsolete. Logistics, which has dictated almost every war in human history, would look totally different due to the fabrication technology, though limits to propulsion technology and the vast distances involved would cause other issues. The Oort pilgrims would have the advantage of locality--they could see and respond to any movements from the inner solar system within months while delaying or hiding their defensive actions until the last minute. But the fabrication technology would render pretty much anything expendable, and it might be feasible to turn maybe a few hundred Kuiper belt objects into a swarm of self-guiding missiles or something while the Oort pilgrims wouldn't have enough raw materials to really hurt, say, Earth.

On the subject of privateers, why is the author so insistent on the danger of crashing ships into planets? What does the math look like when space craft like he describes hits the upper reaches of our atmosphere? At those speeds, could a space craft really penetrate far enough to cause terrestrial damage?

An example: Project Thor / "Rods from God": http://en.wikipedia.org/wiki/Kinetic_bombardment

The linked article seems to mention re-entry friction as a problem yet-to-be-solved:

The system would also have to cope with atmospheric heating from re-entry, which could melt the weapon.

Then there's the question of whether or not heat is truly the most immediate issue. NASA and USAF had to actually fly an airplace near and past the speed of sound to see how the properties of the atmosphere changed when compressed. Is it logical to hypothesize that similar changes may be encountered as speed continues to increase?

I don't think melting is that big a deal. It's still the same amount of mass, only now it's molten steel instead of steel rods.

It'll start breaking into little blobs, though, which will have less and less power.

It doesn't matter. As long as each "blob" is heavy enough to resist deflection by the wind, the same total mass will impact at about the same speed. The only downside I can see is that the blobs might hit at slightly different times, which would reduce the instantaneous force on the target. But I think it would transfer the same total energy.

The same total energy would be transferred, but it would be spread out over a larger area. If the area is sufficiently large, then all you've done is raise the temperature of Germany by one degree for a while.

(Still, there are plenty of configurations that make good kinetic-kill weapons with a manageable amount of re-entry heat. Think large rods with good amounts of mass and small cross-sections. This is an engineering problem, not a show-stopper.)

Figuring Germany at 357021 sq. km, and "1 degree" to raise the equivalent of a meter of water by 1 Kelvin, gives 1.5E18 J.

If I did my math right, that's the energy in a 400 megaton bomb, or 17 kg of antimatter. The US nuclear arsenal is about 2500 Mt.

I don't think you'll be able to distribute that much energy so uniformly. Almost certainly you'll end up with all of it dumped into the surface, with people, land, and cities burned to a crisp. Only a few people in mines or deep valleys might survive.

The article mentioned tungsten, which has an absolutely preposterous melting point. I doubt it would melt moving at typical orbital velocities, but even if it were to be moving faster you could easily make the front of the projectile ablative.

A relativistic speeds, having airbags is not a free pass. Great, it hit your atmosphere and disintegrated. Now your atmosphere hits you.

As mentioned in the post, David Weber's Honor Harrington series operates very much like this. I've read a few of them and enjoyed it. Nuances in space combat in his stories tend to be important.

http://en.wikipedia.org/wiki/David_Weber#Honor_Harrington_se...

Also, it's worth watching this scene from Mass Effect 2. It's amusing :)

http://www.youtube.com/watch?v=7GqqDCe4Yrs

Assuming a ship of 500 m in length, and weighing 10,000,000 tons (100 times heavier than the largest aircraft carrier), the firing of a 20kg shell at 1.3% of the speed of light requires a momentum transfer of 0.008 m/s from the ship. Assuming constant acceleration, the firing requires a shell acceleration of 1.5E10 g, which is done in 130 microseconds.

A velocity change of 0.008 m/s in 130 microseconds means the ship itself has an average acceleration of about 60m/s/s or about 6 g. However, this assumes the entire ship is rigidly coupled to the firing system. If held together by normal structural forces, which propagate at best at multiples of the speed of sound, then no more than 1/2 meter of other structure can be involved. It's more likely the equipment itself will have 100s of g of stress.

The acceleration requires 1.5E14 Joules, or 35 kT of TNT, which is what the clip said.

A fascinating read and good outline for what space battles require, but not a predication of what future space combat will look like. By limiting the discussion to only technology that we could build today, the exact scenarios in here will never play out.

Large scale space combat will play out only when humans can build these weapons cheaply, and have an incentive to build them at all. That is decades from now. By the time a human society decides to construct the ridiculously expensive space warships and defenses the author talks about, we will have much more advanced technology (that is probably a lot cheaper to.)

My favourite space combat scene is the one on the way to Home in Protector.

I also enjoyed Niven/Pournelle's descriptions in Mote in God's Eye - to paraphrase, space combat is incredibly boring except for brief flashes of terror.

I really liked Lucas' treatment of space combat with capital ships in Episode III. You line up next to each other and start blasting, just like they did back in the good old days of pirates on wooden sailing ships. Of course this is incredibly stupid and immensely destructive to both ships but it makes for awesome explosions.

But I think doing this within range of a planet's gravity well isn't too intelligent. Lose power and down you go.

I always appreciated the space battles in the X-Wing series of computer games. That's the way I see it, large capital ships with single-man fighters buzzing around them. But since we have semi-automated drones with human pilots on the other side of the world with a satellite link, I would have to assume those single-man fighters would be unmanned.

But Niven/Pournelle's idea of space combat is most likely what we would get.

> But I think doing this within range of a planet's gravity well isn't too intelligent. Lose power and down you go.

Sure, if you're dumb enough to park yourself in a decaying orbit.

I believe it is well established in Star Wars canon that the drivers of the capital ships don't always seem to be the brightest guys in the fleet.

http://www.projectrho.com/rocket/spacewarintro.php for all your back of the envelope needs.

I think http://www.projectrho.com/rocket/ is by the same guy as OP, actually - the forum post made many points I recognized from Project Rho.

Well, that turns out not to be the case. I'm the author of the Project Rho site, and I did not write the essay on the Spacebattles forum. But I agree with all the points the poster made, he just wrote the article more succinctly than I did in my website. ;)

Those monitoring platforms if they emit any signals they can be detected and destroyed. During the early days of Iraq war, Iraq had a GPS disruption device that floods the wavelength with their own GPS signals. The first thing US did was to send a missile that use disruptor's own signal to track it down and destroy it. Establishing enemy's fog of war would be first priority.

It is very unlikely battle's will occur in open space if both sides knows each other's capability. The side with slight disadvantage will seek to level the playing field by heading towards asteroid field or unmonitored planets.

Once they arrived at the planet, one strategy for the orbital battle field is to go into an extreme elliptical orbit. The more skilled pilot will be able to calculate the opponent's possible orbit and tries to outwit his opponent. As the pilot approach the perigee of the orbit, the cinematographic tense scene panes to the pilot's face as the ship slows to the escape velocity in the upper atmosphere. Only to escape tattered and draught, and approaching the enemy hidden by the planet horizon.

This whole thing about "stealth will be impossible, because everyone will have dispersed observation platforms," seems very handwavy to me. If detection is so easy across vast distances, then ultimately observation platforms shouldn't be able to survive unless they have stealth. Otherwise, no matter how cheap you can make your observation platform, you can make something else that will destroy it for much less.

I imagine space warfare to be a complex "cold war" of vast distances, with robot missile and detection ships tightly beaming waste heat and information in carefully chosen directions. There will be complex games of deception and counter-deception. It will be a matter of tricking the enemy into critical errors about what you know and don't know about the disposition of their forces.

The situation where everybody is using torchships, and everybody knows where everybody is at all times is similar to the Surface to Air Missile dominated era of aerial warfare of the 70's. There will be tremendous incentives to someone to develop workable stealth of some form.

A destroyed observation platform is just as useful for defense as a working one :) I'll replace my cheap observation platforms after I've disposed of the threat that just gave itself away.

It will be a losing battle if the resource that destroyed your platform is cheaper than your platform. And while your're "disposing of the threat that just gave it self away," you're actually falling into my trap, for I've only sent that drone to get you to maneuver and give your other forces away, so my other disposable stealth drones can spin-up to high-energy missile mode and blow them up as well.

See, you can't just handwave stealth in space away. If you think you can, you just haven't thought it through quite enough.

I see what you're getting at, but I wouldn't call that "using stealth". Surely the demolition of one observation platform isn't going to raise an eyebrow. If I'm defending a solar system I have tens of thousands of observation platforms that get taken out by asteroids and comets from time to time.

Trying to create a diversion isn't really effective at the scale of a solar system (or greater). While I might send a small fleet at your drones, you still have to get at me from somewhere, and that probably involves destroying more drones. But why bother? Getting to my base at the center of the solar system is going to take you more than a few minutes, I'm going to figure out where you're really coming from.

It makes more sense to use drones for reconnaissance, and then just go at your opponent with a bigger fleet.

I see what you're getting at, but I wouldn't call that "using stealth". Surely the demolition of one observation platform isn't going to raise an eyebrow.

You're forgetting that holes in your observation cloud open windows through which my drones can beam waste heat. Of course I wouldn't be trying to destroy just one drone. The point is not so much to divert, as to cause you to reveal your resources and to give mine more opportunities to use stealth.

Also, the scenario here is not the invasion of a solar system. I thought it was the control of a particular resource like an asteroid. But if you want to play "invasion of the solar system" then I'm game.

It makes more sense to use drones for reconnaissance, and then just go at your opponent with a bigger fleet.

Only up to a certain point. If you create a tremendous concentration of resources and industrial output such as an awesome battleship, you might have something that can beat any individual craft in a 1 on 1 battle, but you've also created an opportunity to hurt your side a lot with only a very small expenditure on my part. This is especially true with stealth.

I think Hamilton nailed it when he talked about kinetic weapons and 'wasps' (aka small bots that can move in ways a human occupied ship can't)

Indeed - in this particular series (The Night's Dawn Trilogy) space warfare was conducted at very long range by kinetic drones, fired from spherical ships.

I imagine, that this space warfare as described in article will only be preceding the real war. once this unmanned missiles are exhausted . if invading force has won. it will try to land on the resource that it is fought for, (planet, moon, asteroid, space station). and once they are landed it will be more classical warfare. (so don't worry there will still be blood). so this is very much like trench warfare.

All this is valid for current technology . and same species war (humans vs humans) , but war between aliens and humans will most likely be war between Von Neumann probes. if you lose you got terraformed or planetXformed. all will be very quick and precalculated. so if you are not prepared in advance for all possible situations. you will probably lose. (or not be able to terraform). pretty much all you can do to protect you r self from alien Von Neumann probes is find it first in space or early stages of development and try to reverse engineer it.

"there's no stealth in space, but there most certainly is stealth in an atmosphere."

It would allow for ambushes, and fake-ambushes.

A lone-ship running from a fleet, carrying a local governor, running past an uninhabited planet, away from a chasing enemy fleet. The lone-ship passes right next to the planet and keeps going. The enemy fleet follows. When the fleet is passing next to the planet, will there be an ambush waiting? Will missiles hidden in the moon orbiting the planet emerge and fire in a cloud of <"thunder" replacement>?

The algorithm deems the chance of an ambush springing from the planet atmosphere as "possible", and the fleet retreats.

Unless you need to make a gravity-assisted course correction, why would you follow in the path of a ship? Ambushes aside, they can drop all sorts of things behind them that you don't want to run into.

Well my point stands, ambushes can be held in atmosphere.

Let's say enemy fleet regularly uses the planet to make a "gravity-assisted course correction"...

Do any other hacker news readers check out spacebattles.com? I'm glad to see it on the front page, I've been a member there since '01

What's the difference between a spaceship and a missile once you remove the human passengers and pilots?

A missile is likely to be more efficient and cheaper, by a massive margin. Otherwise, none.

Not much. The main difference between a missile and a robot controlled spacecraft is that the latter has more propellant. The spacecraft presumably is intended to return while the missile is just has to arrive at the target. The spacecraft will have roughly 4x the propellant [1] propellant to enter mothership to target trajectory [2] propellant to slow to combat speed at target [3] propellant to enter home to mothership trajectory [4] propellant to slow to a stop at mothership. A missile only needs [1].

The OPs problem here is that in the attempt to change the analogy from naval combat to aerial warfare is that he fails to grasp the medium again.

Space is big, space is empty. FTA this means everything is easily trackable, not only are thrusters visible from across the solar system (except perhaps if you're headed directly for someone, but the thrust required there would be insane), but even every object in the solar system is glowing in infrared energy and thats background objects, not to mention you've strapped nuclear power plants, life support and whatever other heat producing apparatus onto your ship to make it glow even brighter.

The problem with being visible from a distance means it favours those who can hide. Basically, it favours mines. It's simple strap a laser onto a small rock, bury capacitors inside it and have them charged by solar panels. Why? Because the aim is to one-shot your target somewhere important. The mine is disposable, if it one shots the target you might get lucky enough to use it twice. If not you'll have dozens of others waiting. You've got 3 targets: Power supply (nuclear reactor/capacitor bank/whatever), main engine (you cripple their thrust and they're a sitting duck) and control centre (heck, you're likely able to nail all habitable space in one shot as a space ship is more likely to have a vastly expanded cockpit rather than a whole ship of habitable space)

The other problem with space combat is heat. Before you'd even fire a missile or a bullet, you're going to be aiming infrared lasers on your targets from light minutes away. If a ship is habitated then you only need to get it to the point where the life support can't shift enough heat to keep the air temperature below 40C. In uncrewed ships you're talking hot enough to make processors malfunction, which isn't considerably hotter than people can tolerate. These might cope better as cooling can be dedicated to very small areas.

The problem with space is that objects can get very hot, very fast and unless you bring a lot of material to heat sink and dump, you've got problems.

Space will be a war predominated with mines and heat. There are currently about 25,000 objects in space. If only 1% of these are ship-killer mines, would you attack Earth? Well, you'd need more than 250 ships, assuming you're able to kill all the mines in a very short time before they can refire.

Want to attack a mining base in the asteroid field? Find the rock without the massive laser hiding in it! Furthermore, try to wage an effective assault when you're pulverizing everything within a million kilometers of you, and still have the weapons/energy/heat sink capability to fight your target that has a massive rock of shielding and heat sinking, versus your ship.

What about launching asteroids or comets at your target? Well 1 if it's viable to nudge an asteroid from hitting earth, then it's viable to nudge the asteroid your in so that it's missed.

Mines are just as detectable as anything else. Problem: how does your mine know when to go off? If it has sensors, it has electronics; if it has electronics, those electronics are running at something above 3 Kelvin; if you're running anywhere above 3 Kelvin, you can be seen against the cosmic background.

Also, asteroids are incredibly vulnerable, because they can't move. You don't even need to get into range; just boost up another rock and nudge it into a collision trajectory.

I don't disagree, but remember the number of asteroids over 100km is around 200. The number of asteroids over 1km is between 700,000 and 1.7 million. That means the very big asteroids are between 0.0003% and 0.0001% of the objects in the asteroid belt. Given that the smallest known Aten asteroid is ~5m in diameter, then it's an easy conjecture that the asteroid belt is likely to have tens if not hundreds of million asteroids <1km in diameter.

They're going to have enough mass that blasting them is going to be impractical. It's going to be a waste attacking a mining asteroid if you're dumping hundreds of munitions at every nearby rock.

> If it has sensors, it has electronics; if it has electronics, those electronics are running at something above 3 Kelvin; if you're running anywhere above 3 Kelvin, you can be seen against the cosmic background.

This is very true, however given the variation in albedo's of asteroids and meteoroids then there's going to be a wide range of 'normal' temperatures for asteroids. With enough processing power you could assume that people would eventually start calculating asteroid albedo vs distance from sun vs apparent temperature. If you've got a light rock that's hot as all hell, then you might be best to shoot it just in case. Probably not likely for civilians at least, even the military might not want to be running too much processing power as they'd have greater heat sinking issues to worry about.

The real thing that will determine how hard or easy to find mines will be is human mining. How much dirt and debris are we going to be producing, or even purposefully producing. If we're mining bigger asteroids are we going to require ships to land, or simply dump payloads into orbit for ships to snag. If we're doing the latter, then we're talking about hundreds of objects running well above background levels. How much rock are we going to strip off an asteroid and leave nearby?

If piracy or warfare becomes real, then mining companies will likely want to limit the approach vectors for incoming ships. What better way than dumping copious amounts of junk in your orbit. Given that a cubic meter of silica weighs around 2500kg, then you're not likely to crash your ship into it at any speed. Put thousands of these in orbit, and people are only going to approach from the clear paths.

Again, all these rocks would be hotter than background, and you only have to mine 1% for it to be a solid defence. Making someone take 100 shots in 1-hit wins warfare is a very effective defence.

What if you launch a surprise attack by launching a missile at relativistic speeds?

Unless you are talking about yet to be invented explosives, at relativistic speeds you may as well launch a rock. The explosive power of your warhead will probably be irrelevant when compared to the kinetic energy of the projectile.

But, fairly enough, launching anything at relativistic speeds requires yet to be invented propulsion systems that will require energies much larger than any explosive we know today.

For maximum efficiency, you could launch a lump of antimatter at relativistic speeds. That should take care of the details.

hmmm... so the author is using today's understanding of technology to substantiate future outcomes. No can do - I say!

Would it be feasible to use a nuclear device as a shotgun?

That is, most of the kinetic energy of the bomb is directed (like discussions for the bombs in the Orion project). The bomb would be optimised to send tungsten bullets off at X km/s.

Then put that as the payload of a missile.

Edit: Fragmentation bombs was discussed in the second page of the article. Hmm... this would need a very tight spread of the heavy pellets, which is probably not possible with a nuclear weapon?

Edit 2: Add a 2nd level of explosive drive to the fragments? They disperse a bit (to make them hard targets) but know where the target will be and when. More like submunitions, I guess.

Edit 3: Rail guns to send (small) kinetic missiles at a high initial speed? These could potentially run in stealth mode for quite some time, before doing final course corrections.

Information and stealth are the biggest assets in space war so maybe that is why we dont see aliens chit chatting all over. A species wins a war by making the enemy think it has won, while hiding out at a new home base to build up weapons.I see earth as an extension and continuation of that war. We don't know where our allies are, So that when they discover our position and interrogate us they won't find the rest of the hive. the winners of war will be the species that hides the best.

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