Planetary Invasion/Defense

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osmium
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Re: Planetary Invasion/Defense

Post by osmium »

I'll make a quick reply.
To makes things more interesting, remove the enemy fleet. Have there be something like a combat over the planet because the enemy ship was hiding behind the planet. You could maybe have there be some sort of collision if they got going fast enough and the accelerations that are possible are low enough, but suffice to say have all air power knocked out. The problem is that logically species will prepare for the way the world is. If there are tornadoes there will be tornado drills. If there is the threat of invasion there will be bombardment drills. Allies will have safe zones and will just vaporize anything else that moves on the planet, there would be no need for communication and nowhere to hide.

As for technology, Mjolnir is correct, unless you're going to have some sort of benefactor race that taught the race how to build certain technologies and so while they understand and developed them first, they sort of got a headstart in one area and hence design in the other sort of petered out. It's really really hard to avoid making chemical weapons before others, you'd need some sort of repressive regime and society that is against technological progress (the only reason why China isn't 4000 years ahead of us despite having fireworks for so long).

That being said you're perfectly welcome to ignore reality and rewrite stuff how you want to, you're just asking for more suspension of disbelief out of your readers especially if there isn't a good plausible reason / solution. I also think for impact you might want to have well defined motivations and goals for the two sides, why are they in this conflict, for what reasons would they stop fighting, are they external or internal etc.

-O

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Mjolnir
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Re: Planetary Invasion/Defense

Post by Mjolnir »

I gave some plausible reasons for specializing in energy weapons...physiological limitations to dealing with recoil and noise, for example. It's the degree of disparity I have an issue with...the idea of projectile weapons being left at WWI levels while energy weapons are highly developed. Perhaps they replaced advanced high-power projectile weapons with energy weapons, but that doesn't make their projectile weapons less advanced.

Prerequisites for producing projectile weapons are useless or only of very indirect use for producing energy weapons. Prerequisites for energy weapons, on the other hand, imply the capability of producing projectile weapons. A tube, a projectile, and some propellant get you a basic firearm. An energy weapon requires a high density energy source and a high density, high power pulsed power source. You're not going to get close to making energy weapons without industry with all sorts of machinery that is more than sufficient for producing guns.

Back to the scenario at hand...
If the humans don't have local support that can hide them, they need something that protects them from the fleet in orbit, and really from any alien controlled military aircraft. Say part of the planet suffers severe seasonal storms, enough wind, rain, clouds and lightning to keep aircraft out of the sky and make it difficult to tell human activity on the ground apart from Logieri civilians...taking out optical observation and greatly interfering with radar, thermal, etc. The humans land ahead of the storms and disrupt communications...and then they only have to deal with Logieri on the ground and the weather until the season ends and the storms clear. If the enemy fleet's not gone by then...it's time to surrender.

The situation is still a matter of surviving. I just see no way for such a small number of humans to maintain control of an inhabited alien planet or even a well-defended city while a hostile fleet has control of orbit. (and how did they capture such a well-defended city without destroying the defenses?)

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icekatze
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Re: Planetary Invasion/Defense

Post by icekatze »

hi hi

If you can build a rocketship, you can necessarily build a projectile weapon. :P

One thing tactic that might work for the humans would be to use decoys. Depending on the capabilities of the orbiting fleet, they might waste a lot of time going after fakes... but they're going to have to be pretty convincing fakes, so I don't know if that is something the invaders would have on hand.

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Re: Planetary Invasion/Defense

Post by discord »

if the hostiles control the orbitals AND have access to military orbital bombardment.... and the friendlies do NOT have friends on the ground? with no expected relief within the next week or so? the commander that does not surrender under those circumstances is either fighting a utterly total genocidal war(expecting the hostiles to not take prisoners) or certifiably insane.

change any of those, and the commander just might not get shot for treason assuming he survived long enough to stand trial(the hostiles just might kill him before his own men get around to doing it.)

a simple question, can humans even forage on the planet? is the biology at all compatible?

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bunnyboy
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Re: Planetary Invasion/Defense

Post by bunnyboy »

Orbital forces are meaningles if the target is good for hiding.
Image

But good point. If humans can't eat a thing, the war is soon over for them.
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sunphoenix
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Re: Planetary Invasion/Defense

Post by sunphoenix »

Yeah... that hiding only works if you are NOT using total WAR tactics. If you are concerned about indigenous inhabitants! The U.S. military could have killed every damn thing in the area if they would have been allowed to use every nasty and insidious weapon in our arsenal to kill anything living crawling or otherwise in those mountains.. but public opinion would not have supported such excessive - but damned effective force!

Things get even more "pear-shaped" if you add nuclear bombardment, chemical carpet bombing or even biological weapons... not even including hunter killer robotic autonomous inorganic weapons.

EDIT: LOL... H.A.I.K.U. [Hunter Autonomous Inorganic Kill Units]
Last edited by sunphoenix on Thu Mar 24, 2011 6:18 pm, edited 1 time in total.
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Martenzo
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Re: Planetary Invasion/Defense

Post by Martenzo »

Alright. Let's clear something up. Orbital bombardment is not an option for the Logieri. For them, the planet represents many decades and trillions spent on infrastructure development. The Logieri are not (at least at first) willing to destroy decades of effort development over what they believe is a minor border skirmish.

Second, food and ammo are not an immediate problem for the humans. The humans were originally invading and they expected a months-long ground siege for the major cities on the surface. They have sufficient stockpiles of food and ammo, even if their vehicle stockpile is better-suited for an offensive siege. When faced with such a massive ground force, the Logieri surrendered almost immediately, which was an unexpected, but smart move on their part. On the human side, public support for the war would evaporate immediately if the humans just started attacking a civilian population that has already declared a surrender.

And now a note on communications. For most species in the setting (including Humans and Logieri), the fastest form of interstellar communication is starships carrying messages. Essentially, this means that it's somewhat difficult to stay ahead of fleet movements.

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bunnyboy
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Re: Planetary Invasion/Defense

Post by bunnyboy »

I read again the first message.

Humans have selected few high valued targets, like capital city, religious leaders, nuclear reactors, traffik control centers, etc and take them for hostages.
Then they hide in cities and use population on their shields.
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Mjolnir
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Re: Planetary Invasion/Defense

Post by Mjolnir »

Martenzo wrote:Alright. Let's clear something up. Orbital bombardment is not an option for the Logieri. For them, the planet represents many decades and trillions spent on infrastructure development. The Logieri are not (at least at first) willing to destroy decades of effort development over what they believe is a minor border skirmish.
That only prevents them from using large scale strikes against humans in locations with valuable infrastructure. Unless they've developed the entire surface of the planet or concentrated everything of importance in a single point, humans moving from place to place will be exposed and can be taken out with minimal collateral damage. And orbital bombardment doesn't necessarily mean dropping asteroids to obliterate continents, they could very well involve precision strikes to take out individual tanks in urban environments.

Concentrations of force almost anywhere could be taken out with little overall collateral damage. A dispersed force is safe from orbital bombardment but far more vulnerable to ground forces. An attempt to respond to a threat from that involves concentrating force...

They could pick a city and abandon most of their vehicles, using infantry forces concentrated in a variety of high-value locations to hold the city. They'd have to pick their locations and spread their forces carefully...taking out a few buildings the humans are using as headquarters and living quarters could still break the human occupation without much loss. Large dams, manufacturing facilities, power plants, etc. Threatening to destroy infrastructure might make them less willing to provoke the humans, but would just make the situation with the locals even worse...and those in orbit have similar threats they can make: blow up a power plant, and we take out your headquarters, even if it takes out another power plant.

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bunnyboy
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Re: Planetary Invasion/Defense

Post by bunnyboy »

For precise strikes, guided missiles are needed. Matter dropping will scatter on radius of miles and interference will eat power from any energy weapons.
The fleet is easy to detect from planet surface and when missiles are launched, the need good amount of time to travel & find the targets, so alarm is given.
Humans have couple of minutes to go inside of buildings or under bridges and shoot some anti-missile-missiles.

If Logieri wants to hit humans from orbit with minimal collateral damage, they need drop stealth missiles under horizon and have a some smaller reconno... scouting vehicles/soldiers to mark acceptable targets.
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sunphoenix
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Re: Planetary Invasion/Defense

Post by sunphoenix »

Nah. Not really. Laser guided, unpowered, fin-stabilized, 1ton steel I-Beams with perhaps a sub-munition kinetic-kill triggered warhead {if your just feeling mean} would work just fine and not leave much warning of its incoming threat... especially if you drop like a couple hundred of them! :)

Also remember... heh... rocks are even cheaper! :)
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Re: Planetary Invasion/Defense

Post by Number 6 »

I think the Humans are just screwed.

Unless you give the Humans Huge jump in Stealth tech where the Logieri can't find them All the Logieri have to do is load up a Virus that kills humans and bam end game for the humans little loss for the Logieri.

Maybe the Planet is Sacred to more than just the Logieri?
That would keep the humans and the Logieri from trashing the planet and the cities.

Maybe another idea that the Logieri on the planet are a sect that is devoted to peace or something?

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Mjolnir
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Re: Planetary Invasion/Defense

Post by Mjolnir »

bunnyboy wrote:For precise strikes, guided missiles are needed. Matter dropping will scatter on radius of miles and interference will eat power from any energy weapons.
And why can't you bombard with guided projectiles from orbit?

Also, particle beams would not fare well in atmosphere, but laser weapons that are effective at space combat ranges will most likely still be somewhat effective against ground vehicles, and definitely against personnel in the open.

bunnyboy wrote:The fleet is easy to detect from planet surface and when missiles are launched, the need good amount of time to travel & find the targets, so alarm is given.
Humans have couple of minutes to go inside of buildings or under bridges and shoot some anti-missile-missiles.

If Logieri wants to hit humans from orbit with minimal collateral damage, they need drop stealth missiles under horizon and have a some smaller reconno... scouting vehicles/soldiers to mark acceptable targets.
There's no way you're stealthing an object entering atmosphere at near-orbital velocities. However, interceptor missiles are a lot more complex (thus more expensive) than unpowered guided kinetic projectiles, and if your vehicles can't venture beyond a quick dash of non-expendible cover, the bombardment's effective without ever having to actually hit one. Plus the attacker's projectiles can be under the cover of the attacking ship's point defense systems for much of the trip.

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bunnyboy
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Re: Planetary Invasion/Defense

Post by bunnyboy »

You can throw down from orbit whatever you wan't, but on atmospheric entry, friction will throw them slightly of from course, maybe couple to thousands of yards. Any guiding or transmission systems don't work because of heat, until the speed is sloved down. And the time for this is counted in minutes.

Lasers have problems in atmosphere. Energy around 1 megajoule in cubic centimeter will turn air to plasma, which cause to laser defocus and disperse energy. And any clouds or pollution makes it worse, because they absorb and scatter the light. And when the laser hit the target, evaporated material will cloud and shield the target.

You are right of about that, entry is impossible to stealth. But doing it out of horizon (visible/monitored area) gives it change to come unnoticed.
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Re: Planetary Invasion/Defense

Post by Arioch »

bunnyboy wrote:Any guiding or transmission systems don't work because of heat, until the speed is sloved down.

Back in the mid-60's we had guided missiles that could accelerate at 400g and reach top speeds in excess of Mach 10, and were accurate enough to intercept aerial targets. The total flight time was measured in seconds. I don't buy that starfaring technology can't create effective guided orbital-drop missiles that are as accurate as today's JDAM's.

Very high frequency lasers shouldn't have any trouble penetrating atmosphere. These might have to be specialized for orbital strike (and perhaps not very useful in space-to-space application), but I would expect them to be very effective.

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Re: Planetary Invasion/Defense

Post by osmium »

Also it's not hard to acquire a chunk of matter large enough that you could sling it at a planet and cause damage over a huge area. Aiming is less important in that case, so you don't *need* to make anything fancy like a guided projectile, just calculate the trajectory and have your projectile have enough inertia and speed to get close enough. If you care about collateral damage I'd bet on lasers being your best bet.
-O

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bunnyboy
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Re: Planetary Invasion/Defense

Post by bunnyboy »

Not sure, but seems to be that spaceshuttles have a entry speed of Mach 24.
In that speed, the bomb can reach target in 15 seconds from 100 kilometres.
ISS is in 350 km away from earth, where it travel around world in 91 minutes, but because atmospheric conditions it is still falling 2 km per month.

The space fleet can't be stationary, unless having altitude somewhere 36 000 km! That means they aren't constantly present, which gives humans windows to operate.

And for collateral damage. Think that there are terrorists hiding in your home city. Do you have enough trust that collateral damage of effective "chirurcical" bombing is acceptable?
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Re: Planetary Invasion/Defense

Post by discord »

bunny: well on the subject of hiding, hiding one man(or even a few hundred of them) with support of the local populace is one thing and quite doable, hiding something like a hundred thousand including hundreds of tanks and aircraft WITHOUT local support? forget it, not possible.....well, unless you bring magic klingon cloaking devices into the equation.
and with the kind of firepower available to military space craft, if you can see it, predict it's movements well enough for the ranges involved, you can kill it, and any ground based target may as well be stationary sitting ducks as far as the ships shooting it are concerned, it's not even target practice...might take advantage of the situation and calibrate the guns while at it though...

edit:
given the technological level that has to be involved, and how the targeting systems on any military space craft would have to be, and given arioch's laser, I'd feel pretty safe standing a few meters from the intended target, assuming a relative low power laser intended for taking out a single human, on kinetic weapons? a few houses away? sure, no problem, the only reason I'd prefer to be a bit farther away is shrapnel from the impact, the weapon WOULD hit the intended building, only thing that could change that would be surface 'defense' fire, and then only to change the trajectory slightly, enough to make it dangerous to be in the area.

i stand by my previous statement given the circumstances if the human commander does not surrender ASAP, he should be shot for treason, at least one of the circumstances must change for this to be realistically viable, take the gunships in orbit(thereby taking away most of the orbital firepower, at least ACCURATE such) out of the equation, or give the humans local support(giving them a chance at hiding), or expecting the fleet back soon....without any of these....even given optimal performance of his troops, there is not a chance in hell the unit would be combat effective after one single month(probably not even a week, or if the hostiles are willing to take serious, not total just serious collateral damage, not even a single day) of engagement.

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Mjolnir
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Re: Planetary Invasion/Defense

Post by Mjolnir »

bunnyboy wrote:You can throw down from orbit whatever you wan't, but on atmospheric entry, friction will throw them slightly of from course, maybe couple to thousands of yards. Any guiding or transmission systems don't work because of heat, until the speed is sloved down. And the time for this is counted in minutes.
Guidance systems in existence now can and do work despite reentry heat.

bunnyboy wrote:Lasers have problems in atmosphere. Energy around 1 megajoule in cubic centimeter will turn air to plasma, which cause to laser defocus and disperse energy. And any clouds or pollution makes it worse, because they absorb and scatter the light. And when the laser hit the target, evaporated material will cloud and shield the target.
High power laser weapons of the sort described here (a major part of the armament of a fleet of warships) are designed for ranges far greater than those involved in hitting ground targets, moving and accelerating at far higher speeds. They could easily ensure a direct hit on the first shot, and subject a ground target to consistent repeated and sustained fire that no target in space would ever receive. They could reduce power and defocus the beam to prevent ionization, deal with further defocusing due to atmospheric heating and turbulence, and still precisely and reliably kill ground targets.

bunnyboy wrote:The space fleet can't be stationary, unless having altitude somewhere 36 000 km! That means they aren't constantly present, which gives humans windows to operate.
That only applies if they are in orbit. If their acceleration and delta-v capabilities are at all like those of even the Terrans in Outsider, they can hover above the target at whatever altitude they prefer for the duration of the bombardment.

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Re: Planetary Invasion/Defense

Post by Zakharra »

Hello there. I had an idea that might give the humans a chance against orbital warships. If the humans were intending to occupy the planet as a forward base (land grab), they would likely have expected a retaliation by the Logieri.

Now to fortify their hold on the planet, several minelayers might have been included in the human task force and when they had to retreat, the minelayers were instructed to dump all of their mines in orbit. If there is significant orbital debris, the mines might be fairly well hidden and hard to detect and destroy. It could only take several to destroy a large warship.

They could also be under the command of the human forces on the ground and make it very difficult for the Logieri to assume a close enough orbit to give ground support or even land their own troops unless they spend a lot of time clearing everything out of orbit that might be hostile.

If the Logieri need to use planet side facilities to refuel, assuming the humans blew any orbital/moon based facilcities when they invaded and retreated, the Logieri rescue fleet might be limited in manuvering and in how long they can stay before they need their own resupply. Basically, the mines could be used to deny orbital space to the enemy for a time unless he wants to spend a lot of time just shooting space junk.

I reread the OP and saw this;
The Logieri counterattacked with a larger fleet than expected and the human fleet chose to retreat and wait for reinforcements before commiting to a decisive engagement.
So the human fleet might still be in the system, hanging around the outer planets. If it is still in-system, that could draw off a significant portion of the Logieri's fleet in an effort to track down and destroy the human fleet or just to keep an eye on them incase the humans try a sneak attack. With a combination of the human fleet hanging around and a substantual mine field laid around the planet, that could seriously hamper any efforts by the Logieri to provide anay orbital suspport for the time being. By themselves, the mines or fleet could be dealt with. Together, they are a fairly hard nut to crack.

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