I've designed Star Trek ships using RPG rules. I'm a nerd, ohno!

I had a ship that could beat nearly any ship around it's size on the Z axis. This was great as it was packed with BFGs on the front. Although it could make me dizzy sometimes. =/

catchamber said
How would this interstellar invasion fare against lasers?

Truth be told, outside of science fiction, lasers are really NOT very good weapons for space warfare.

While they lack a lag over a distance of about 1 light-second, they also have to put a LOT more energy into doing damage than a kinetic weapon, moreover they're going to heat your ship up fast, unless you have vast (and easily destroyed) radiators, by the time you've expended enough energy to actually kill an enemy ship you've boiled your crew.

Indeed. Kinetic weapons are some of the most powerful in space.

If you shoot a 10 ton projectile at, say, .2c then it'll have gigatons of kinetic energy released when it hits the target. Fire it at about .6-.9c and then your projectile's destructive potential is equal to its weight in antimatter.

catchamber said
How would this interstellar invasion fare against lasers?

We don't really know, without knowing how that technology is going to develop. Kad's on the money with regards to our current understanding -- laser weapons are effective as countermeasures against certain sensor packages, because of how they gather and use data; but beyond that, as a medium for energy transfer, we just haven't figured out a way to make it worthwhile (not to say we never will). Famous examples are the Star Wars missile defense system and the ABL, both of which were rendered obsolete by ballistic defense systems (ie, iron dome).

Based on our present tech, theoretically you could mount a mirror to the front of your ship and (assuming your reflectivity [albedo] is high enough), the laser is rendered harmless. Perfection isn't something we usually manage, so it's not like lasers are always going to be 100% useless -- but when you look at how stealth ships (air and sea) are designed to mitigate their radar signature, it's likely that 'lasers,' as we currently understand them, wouldn't be effective as space weapons. Not in this scenario anyway -- you could certainly conceive of many uses (melting comets, potentially pushing satellites, communications, etc), but yeh.

Hypothetically, if you lined up enough high-energy plants and enough mirrors and built a big enough laser, you could use it as a defensive stand-off weapon. If it was up to me to attack such a planet, I'd approach from a different axis -- for instance if the laser is on Earth's equator, I'm coming in from the North Pole. Then again, if the planet is capable of building such a weapon, I don't think it'd be a likely target for an imperial occupation -- we'd either control it, and thus we'd be the ones building the laser, or someone else would already own it, and we'd be fighting them at a softer point (if at all).

Maintaining a interstellar empire would require a different way of handling logistics.

My theory is that instead of sending out one ship for a trip at a time, you have to keep a constant stream of ships "checking" on vassal systems. One ship every two months is sent off to the vassal star system to occupy it. Ships make return trips, and as one ship leaves the people subjugated would see another ship come by.

Of course that would mean A LOT of spaceships, but seeing how much material there is in space I have no doubt it could be pulled off. By having a constant line of ships going to a vassal star system would could maintain a interstellar empire of up to a couple dozen star systems.

And as for time and age… Well, there's hibernation, video games and simply changing people's perception of time combined with longer natural life spans. Or hell why even assume the humans haven't become mind uploaded immortal beings by than? I can think of tons of potential technologies used to make the issue of "time" moot for the travelers.

The people on the planets on the other hand, I have no clue. I don't think technology will constantly innovate rapidly, in fact I speculate it could stagnate in the interstellar age.

Kadaeux said
Stealth is impossible in space. Not difficult. Not challenging. Not an engineering problem. Impossible.http://www.projectrho.com/public_html/rocket/spacewardetect.phpSkip straight to "there ain't no stealth in space, do not pass Alpha Centauri, do not collect 200 Spacebucks." :p

Thankfully the sheer vastness of space, the inability to bend light and presumed advancements in intercepting projectile attacks means stealth isn't that necessary anyways.

Keep moving, keep firing, and always change direction seems to be the way you play the space game. Stop too long and the enemy gets the edge.

But I don't really know, I just speculate based on what arguments I hear and listen to those that sound most convincing.

mdk said Hypothetically, if you lined up enough high-energy plants and enough mirrors and built a big enough laser, you could use it as a defensive stand-off weapon. If it was up to me to attack such a planet, I'd approach from a different axis -- for instance if the laser is on Earth's equator, I'm coming in from the North Pole. Then again, if the planet is capable of building such a weapon, I don't think it'd be a likely target for an imperial occupation -- we'd either control it, and thus we'd be the ones building the laser, or someone else would already own it, and we'd be fighting them at a softer point (if at all).

At the moment the theoretical "best" laser we can do with current physics and equipment is a bomb-pumped laser.

Nuclear bomb surrounded by mirrors designed to funnel as much power as possible into the laser emitter. The laser weapon ceases to exist moments after you set off the nuke, but the nuke powers a very powerful laser strike. But even with the best theoretical levels of that technology at this time, if you can make bomb pumped lasers you'd get better results just detonating the nuke inside the enemy ship.

(And contrary to popular belief, without a direct hit or VERY VERY close detonation, nukes as warheads in space is pretty close to useless, if the nuke detonates more than about a kilometre from the target vessel it's effectively harmless..)

So, how about that ramming thing?

I heard that ramming the enemy spaceship tends to disintegrate everyone involved.

Anyhow I imagine that with the right augmentations and drugs, the spaceship pilots of the future will find what some see as "mundane truth" as super duper fabulous fun. By the time society has spacecraft and uses them regularly the rhythm and ways of using a spaceship to wage war will have an appeal of its own.

Hell I am certain by the time we actually have spaceships, we will have a name that doesn't just have "space" as a prefix. Similar to how airships started being called zeppelins. Perhaps a word derived from shuttle will be what people centuries in the future call what we call spaceships.

Well of course, except the whole dying thing. But hey, at least with spaceship fights it seems you always die instantly when the death bolt hits. Worst case scenario you go into the emptiness of space- and lose consciousness in seconds.

I imagine total war would very much be on the table assuming alien invasion.

But what if said conquers more or less want to exterminate the defenders? Is there ways to avert being glassed or obliterated when all it takes is rods from god to devastate the local population of a world?

AlienBastard said So, how about that ramming thing?

I heard that ramming the enemy spaceship tends to disintegrate everyone involved.

Effectively impossible. Your opponent will see you from millions of kilometres away before you even make the attempt. They'll be capable of seeing and avoiding any move you make to try and match their trajectories. That isn't to say you couldn't ram an enemy, but the amount of effort involved would make it look like you're trying to wage a war by herding cats.

catchamber said
What about a solar power laser array suspended by photon sails? A developed system could certainly build a host of them, and then focus their collective beams onto a single target from multiple angles. These arrays could also provide personal point-defense against kinetic weapons, and even be used to propel vessels equipped with their own photon sails.Brute-force conquest is an inefficient strategy for interstellar expansion, given the magnitude of energy being thrown around by both sides. Defenders have so many advantages against direct conflict with invading forces, it'd be much easier to just subvert polities into collapsing or rebelling. This can be mitigated by mental uploading, so every polity has copies of expert tacticians, but even that might not be enough.That's assuming total war is off the table, of course.

A Solar Laser Array is still effectively worthless. To get a powerful laser you're going to need tens of kilometres of sail your enemy could just sit twenty light minutes out and just throw shrapnel at it. And especially useless against kinetic weapons actually. If your enemy fires dumb slugs to intercept your big obvious targets your sensors would never see it before they shred your sails and weapon.

BUT as I said to MDK before someone came and deleted several of his and my posts (Which if you ignore the slightly insulting nature of them, I broke it down massively.) interstellar war simply is not viable.

Let's say you can move a fleet of 10 ships at .2c This is a phenomenal feat.

Your enemy is 10 Lightyears away. It will take you 50 years to reach the enemy solar system at this velocity if we ignore acceleration and deceleration. Your enemy WILL see you forty years before you ever get near their system. Your acceleration will have been big and obvious...

Now lets say the enemy has 5 ships. But they can produce a further 2 ships per year (conservatively). They will have manufactured Eighty more warships when you finally reach their solar system. OF which the newest ships will be at least 50 years more advanced than your previous intelligence.

Even if you, as an attacker, could build five ships a year and sent them as they were built you'd still never overcome the defenders advantage.

IF you could accelerate something to .2c you wouldn't bother with ships, you'd just build large multi-ton dumb rods and fire them at .2c on a vector to intersect with the enemy planet.

Kadaeux said
Effectively impossible.

The ramming spaceship would be already accelerating towards them, and a ramming ship could keep its trajectory aligned as the no stealth thing goes both ways; every time they start changing trajectory, the ramming ship would too. Just like with a missile.

And ramming would likely be done against a bigger ship, which due to inertia likely would have a harder time changing trajectory or accelerate even if the potential speed of a bigger ship is much bigger than a smaller ship.

AlienBastard said
The ramming spaceship would be already accelerating towards them, and a ramming ship could keep its trajectory aligned as the no stealth thing goes both ways; every time they start changing trajectory, the ramming ship would too. Just like with a missile.

And ramming would likely be done against a bigger ship, which due to inertia likely would have a harder time changing trajectory or accelerate even if the potential speed of a bigger ship is much bigger than a smaller ship.

The problem is, a ramming ship requires significant velocity, the more significant the velocity the more delta-v required to adjust velocity, the longer it takes to adjust velocity in an ever-increasing recursive circle. In a proper 100% Hard Science Fiction battle. Just getting within ten thousand kilometres of your enemy is going to be considered a completely beyond effort.

Add in that. For example.

Ship A has 20% mass in thrusters with an efficiency of .8 (pretty good), Ship A is your rammer at 500 tons.
Ship B has 20% mass in thrusters with an efficiency of .8 (pretty good), Ship B is 25'000 tons. But because it has the same mass to weight in thrusters and identical efficiency, it will be capable of course adjustments exactly identical to ship A. It may weigh 24'500 tons more, but with identical thrust to weight ratio it will accelerate as quickly. It'll turn as quickly. (This is assuming both have roughly the same spherical design as well.)

Add on that if you're doing a velocity, say, twice that of the target object, the target only requires half as much effort to move OUT of your way. Missiles gain their agility by MASSIVE thrust to weight ratios (Something like 90% of a typical missile is dedicated to engine) a Starship simply could not keep its course lined up with an enemy ship while maintaining a ramming velocity, especially if under fire.

To ram an enemy ship is effectively impossible for these reasons.

catchamber said A: Which is why you make a large number of small arrays, and coordinate their efforts. Placing them close to a star would be ideal, as they could move just by adjusting their shape, and would make it difficult for invaders to target them. Proximity to a star would also make detecting relativistic rounds easier, thanks to their blueshifting against the solar wind. Stopping every round wouldn't be the goal, but stopping enough of them to maintain the steep advantages the defenders have against the invaders. This is assuming they could even get that deep into the system, which could be prevented by having a sizable quantity of arrays already present.

B: Wouldn't a strategy of total war and genocide through relativistic bombardment make you hated by almost every nearby polity? It'd make sense if it was used as a WMD, limited only to opponents unwilling to negotiate, but not as a conventional weapon. It seems much more efficient to conquer by encouraging interstellar trade and travel, then using those vectors to memetically subvert the locals. That, or by sending in self-replicating, automated warbots, which could hinder their growth long enough for you to invade in a more "traditional" manner.

A: If your arrays are close to a star they're not just effectively worthless, they're totally worthless. They would simply never hit anything that wasn't in a relative stationary orbit. Lets say that you build an array of them one light-minute away from the sun to get the most out of them. It would take the beams from them a further seven minutes to reach earth's orbit.

B: Genocide through relativistic bombardment is the ONLY realistic and viable warfare (Again assuming 100% Hard Scifi) Interstellar Trade and Travel is completely off the table. If it takes someone 40 years to travel 10 Lightyears (And that is percieved, the actual travel time is 50 years at .2c) they're not going to want to go anywhere, and trade is equally impossible, "Let's send a shipment of computers to that colony."

Ship arrives 50 years later to find the colony has more advanced computing already.

Interstellar Conquest simply is not realistically viable, nor is Interstellar Trade or Travel. And that is based off a society which can accelerate ships to .2c (59958.4916km/s) and another inhabited system as close as 10 Lightyears. Make it 20 Lightyears and you've got 100 years travel. 30 Lightyears = 150 years travel. Even though people on board would, according to time dilation, only experience 4/5th of the time lapsed.

For interstellar conquest, trade and travel it is ABSOLUTELY required to bypass one cardinal law. Faster than Light. Though given that NASA is re-examining the Alcubierre drive, maybe, just maybe, it's possible one day. But until that lightspeed barrier can be bypassed, ignored, moved around, etc, then colonies will always be "fire and forget"

I think you overuse the word impossible dude.

I mean, you assume that smashing everything in genocide is the only effective means to wage interstellar war. Why? I could counter that by simply saying that you can send out a counter RKV and blow up such easy to detect [since serious, that RKV going to flare] death weapon. I've also seen people who said RKVs are impossible since they'd move too fast and the costs for making a RKV would be comparable to that of making a interstellar colony craft. I think interstellar genocide would be hard to achieve against another interstellar civ since they'd intercept them. Instead setting up a base and building more invading spaceships in the outer regions of ther system could prove a more effective means of subjugation instead of sending a few big rocks and hoping for the best.

RKVs are to me only good for strangling civs in the crib.

And the trade/interstellar society stuff all assumes that the current pace of time we have will be the same pace for humans in the future. Perhaps humans, in order to counter the issue of long times to travel between stars simply start perceiving time in a way that makes a 45 year time only a week or two? And are you sure innovation is a constant that may not level off? technologically historically has been booms and busts, why would it be any different in the longer term future?

And besides, trade doesn't just have to be tech. Culture, biological resources [which would by the way, be quite rare in a cold, dark cynical hard sci-fi setting] and simply people who want to go somewhere else would all be involved in some form of interstellar trade. Impractical, perhaps, but can we assume that practicality will even matter to humans of the far future, seeing that the only factor is really time to make things and transport with all those raw resources from asteroids?

A interstellar empire I dunno about, but I could imagine a spaceship chain connected to a neighboring star system being subjugated. Yet with so many interstellar space craft required for a subjugation chain I don't think interstellar empires would be that big, like a couple dozen star systems at most. Of course, I may be absolutely wrong.

And as for the ramming, whatever man I think my theories on it are valid enough and what stops the smaller craft form being built in a similar way to a missile? Most a spaceship is not the crew as is.

AlienBastard said
I think you overuse the word impossible dude.I mean, you assume that smashing everything in genocide is the only effective means to wage interstellar war. Why? I could counter that by simply saying that you can send out a counter RKV and blow up such easy to detect [since serious, that RKV going to flare] death weapon. I've also seen people who said RKVs are impossible since they'd move too fast and the costs for making a RKV would be comparable to that of making a interstellar colony craft. I think interstellar genocide would be hard to achieve against another interstellar civ since they'd intercept them.

No I don't. Also note I have said VIRTUALLY impossible.

Instead setting up a base and building more invading spaceships in the outer regions of ther system could prove a more effective means of subjugation instead of sending a few big rocks and hoping for the best.RKVs are to me only good for strangling civs in the crib.

No it couldn't. It's completely nonviable unless your civilisation ALREADY has a vast superiority over the enemy.

And the trade/interstellar society stuff all assumes that the current pace of time we have will be the same pace for humans in the future. Perhaps humans, in order to counter the issue of long times to travel between stars simply start perceiving time in a way that makes a 45 year time only a week or two?

To even suggest that requires no longer discussing hard scifi. You're SERIOUSLY proposing that people perceive a 45 year trip as only a week or two.

And are you sure innovation is a constant that may not level off? technologically historically has been booms and busts, why would it be any different in the longer term future?

Since 1900 humanity's advancements in technology has been a constant and VAST increase with spurts of even greater development that co-incide with conflict. To imply that an enemy who has forty years minimum advance warning your coming won't be advancing and spending big on its military is pure wishful thinking.

And besides, trade doesn't just have to be tech. Culture, biological resources [which would by the way, be quite rare in a cold, dark cynical hard sci-fi setting] and simply people who want to go somewhere else would all be involved in some form of interstellar trade.

No, it wouldn't. There would be no benefit in it of ANY sort. Culture trade is an absolute joke and isn't even really valid on one planet, just look at all the people who move from one country to another and instead of adopting the customs of their new country, just build little microcosms of their old culture.

A polity capable of interstellar colonisation wouldn't NEED to transport biological resources. They'd have transported everything required for a self-sustaining colony with the initial effort.

And people who "want to go somewhere else" is even more of a joke. Governments would not maintain multi-trillion dollar craft to transport a few idiots to somewhere half a century away.

The only possible realistic trade would likely be purely digital transmissions. And even then it'd require stupidly powerful communications technolgies to make it work.

I mean, just look at the example above, those lovely 50 year trips are assuming you're capable of building ships capable of .2c (without even taking into consideration being annihilated by a micrometeorite that crosses your path. If we take it down to a known rough capability, say.

Max 2'000km/s with an acceleration of 1g (Roughly 0.006%c) (Still an exceptionally generous figure)
Max Speed: 0.006c
Acceleration: 1 G
Distance: 10ly

Time spent Accelerating: 2.12 days
Distance Travelled while Accelerating: 0 ly
Time "coasting" at Max Speed: 1667.8 years

Shipboard Time: 1666.67 years
Observed Time: 1666.7 years

Deviation: 0%

So, without magical acceleration and speeds you'd spend over one and a half thousand years travelling to a star 10 years away.

Make it 12'000 km/s and
Max Speed: 0.04c
Acceleration: 1 G
Distance: 10ly

Time spent Accelerating: 14.15 days
Distance Travelled while Accelerating: 0.001 ly
Time "coasting" at Max Speed: 250.13 years

Shipboard Time: 250.04 years
Observed Time: 250.24 years
Deviation: 0.1%

You've still got 250 years to cross that 10 lightyear gap.

Not only do those low figures rule out trade UTTERLY, but that make the concept of war between two such powers BEYOND ludicrous.

Impractical, perhaps, but can we assume that practicality will even matter to humans of the far future, seeing that the only factor is really time to make things and transport with all those raw resources from asteroids?A interstellar empire I dunno about, but I could imagine a spaceship chain connected to a neighboring star system being subjugated. Yet with so many interstellar space craft required for a subjugation chain I don't think interstellar empires would be that big, like a couple dozen star systems at most.

Yes practicality will even matter, seeing that yes the only factor is time, but when it would take half your life to get somewhere nobody except the most desperate are going to bother. And interstellar empire is simply not feasible or possible in a 100% Hard Science fiction environment, 100% Hard Scifi is boring.

Of course, I may be absolutely wrong. And as for the ramming, whatever man I think my theories on it are valid enough and what stops the smaller craft form being built in a similar way to a missile? Most a spaceship is not the crew as is.

Then you would just make it an RKKV.