Invading a Solar System

[Warsie]

I was thinking, in many sci-fi (see Star Wars) the furthest they go is to militarize only only planet. That does not seem like a big threat in the strategic sense.

I was wondering. What about militarizing an entire solar system. Place a shitload of mines in the outer system with the debris and ice, etc with some quick fleet responses. Deeper inwards the terrestrial planets would be hollowed out like Globbus Cassus, making hollow worlds that could also be used as fleet bases; or they could simply construct a few thousand-mile large stations instead. An entire solar system is a bigger bulwark, especially if they 're closer to the Core of the galaxy; where stars and such are closer, so it would be harder for an enemy fleet to avoid the system. Also note that this is space operay; so let's ignore the energy stuff, scale.


But how much numbers would you think be needed for say, the fleets (size in number; and length of warships). Assuming a Star Wars-ish galaxy; would the ships be optimally be larger; as in several hundred miles long at the most? Would there be a good ratio of planet size to ship size, like there is on Earth's ports between battleship to port size. Could a similar thing be found in space?

[Pablo Sanchez]

This whole idea is completely ridiculous from A to Z.

1) Outer space is three dimensional and (effectively) lacks any sort natural terrain features to impede an attacker. This means that, in order to defend all the conceivable approaches to a fixed location in space, one would have to create a sphere of defenses completely enshrouding the entire solar system.
2) Outer space is really fucking big. The "Outer System" by which I guess you mean the Kuiper Belt, is 30-55 AU from the sun. This means that defensive outworks constructed to defend the approaches to this system would probably a have a mass that was non-trivial compared to the entirety of the Solar System being "defended". What I mean to say is, this is not very efficient.
3) Outer space is really big and three dimensional, and by comparison any putative fleet constructed by a Sci-Fi civilization is so indescribably tiny that it might as well not even exist--which means that there is plenty of room for it to go around any defensive formation. Shit, fixed defensive works have long been obsolete in the modern ground military, which is confined to relatively small spaces in two dimensions!

The only sensible solution to these problems is to fortify what must be held (e.g. the planetary surfaces where people live, and critical installations in space like major naval bases) but to place the primary trust in one's own fleet, which is mobile and therefore useful, whereas immobile defenses are completely useless in the context of space warfare on the scale you're discussing.

[Gullible Jones]

4. Don't mention Globus Cassus here. Please.

[Stark]

What's the point of the thousand-mile long starships? If you can build them, wouldn't you already have them if practical? Wouldn't they make a ludicrious sphere of mines totally redundant? Why hollow out a world to use as some kind of defence ship when that suggests you can already build starships of huge volume anyway? What's the point of ANY of it, unless crossing a system is difficult or reinforcements are some time away (ie, not like Star Wars)?

Frankly I consider the 'number and length of ships' thing to be utterly retarded. Are people supposed to just make shit up? Okay, fourteen septillion ships that are four meters long. Wow, valid! Dickstroking is lame.

[Stark]

GHETTO - oh my god Globus Cassus is hilarious. Thanks for the laugh.

[Darth Smiley]

Agreed, with a few nitpicks.

Depending on how FTL works in a given universe, mines might be plausible if the FTL needs stationary jump points or gates. However, the jump point would need to orbit a planet or the primary star, otherwise the mines would have to thrust constantly in order to remain on station.

Also, bases on nearby planets and moons might be justified if the planet of moon in question provides access to resources, or is industrialized in its own right. I could see Saturn or Uranus in this star system being used as refueling stations for He3 starships. Space Travel in general is a fuel hog, and space combat probably more so. The Moon might also be defended, but the only reason you would do that is to aid in Earth's defense.

If you really want defenses (say this is your civ's home star and you're not taking any chances, spare no expense) you might put a few 'asteroids' that conceal really big missiles/drone spacecraft into orbits that put them near likely enemy approach paths.

That said, Sanchez has it right. Trying to fortify every cubic kilometer of a star system is retarded. Trying to fortify even 30 AUs (our to the beginning of the 'outer solar system' requires you to account for a total of about 9.1 * 10^29 cubic miles! Add in the fact that in space there is nothing to stop someone from bombarding any stationary installation from millions of miles away with utter impunity, and any defense become more akin to expensive pieces of target practice.

[Stark]

Bases are one thing - hollowing out the whole planet (or Globus Cassus-ing it) is WAY beyond 'base for doom missiles'.

[Gullible Jones]

On a more... uhh, "serious" note...

I was thinking, in many sci-fi (see Star Wars) the furthest they go is to militarize only only planet. That does not seem like a big threat in the strategic sense.

I was wondering. What about militarizing an entire solar system. Place a shitload of mines in the outer system with the debris and ice, etc with some quick fleet responses.

Although mines are a staple of space opera, they're kind of stupid, seeing how godawful vast space is. As has been pointed out here before... If you manage to stack improvements on a mine until it can actually be effective, you wind up with a drone or a mobile missile platform.

Deeper inwards the terrestrial planets would be hollowed out like Globbus Cassus, making hollow worlds that could also be used as fleet bases; or they could simply construct a few thousand-mile large stations instead.

Now that's just crazy. Even with SW-level tech, taking planets apart takes forever. Actually hollowing the things out under the enemy's nose would require ridiculous dedication of resources. Never mind reinforcing the hollow worlds so they don't collapse.

An entire solar system is a bigger bulwark, especially if they 're closer to the Core of the galaxy; where stars and such are closer, so it would be harder for an enemy fleet to avoid the system. Also note that this is space operay; so let's ignore the energy stuff, scale.

Even in space opera, you have to have some concept of energy and scale. Space is *huge*. Even at the center of the galaxy, there'd be absurdly more space between the stars than solar systems could occupy.

But how much numbers would you think be needed for say, the fleets (size in number; and length of warships). Assuming a Star Wars-ish galaxy; would the ships be optimally be larger; as in several hundred miles long at the most? Would there be a good ratio of planet size to ship size, like there is on Earth's ports between battleship to port size. Could a similar thing be found in space?

The size of ships doesn't matter. What matters is a) their range, b) the range of their weapons, and c) how many you can field. If you want to blockade a solar system, you need to create an envelope around it where your ships are close enough together anything trying to pass through can be killed.

Of course, that's rather dumb when you get down to it, since the vast majority of the space in a solar system is uninhabited. In general it's probably better to destroy as much of their military capacity as you can with fast strikes, assign blockade fleets to each population center individually, and make use of their asteroid belt while you're there. Think interstellar blitzkreig.

(Again: space is *huge*. Even inside solar systems. The concept of "occupied territory" disappears when you're talking about literal quadrillions of miles in any direction with nothing but cosmic rays and the occasional molecule or grain of dust.)

[Gullible Jones]

Ghetto edit: on second glance, forget what I said about the ridiculous envelope blockade. That would be very easy to overwhelm. Any kind of "border" established in empty space would be absolutely meaningless.

Basically it comes down to this: if FTL has choke-points, blockade said points. If it doesn't, then take all the big targets in the system as fast as you can, and put fleets in orbit around the planets.

[kinnison]

Static fortifications are ridiculous; active, fixed defences are not, as long as they don't rely on a single control point. Classic examples of what I am talking about are the Ringworld defense laser and the sunbeam from the Lensman series.

The only other effective defense is a forcefield that uses essentially no power to operate. There are many examples of this sort of thing in fiction.

With an active defense, the main problem turns into finding the invading ships so that you can shoot at them. As several people have pointed out, a solar system is BIG - to say nothing of interstellar space. However, this might be helped somewhat by the fact that most fictional space drives have an exhaust, and that exhaust is very bright and would have dinstinctive spectral characteristics.

[Lord of the Abyss]

Depending on how FTL works in a given universe, mines might be plausible if the FTL needs stationary jump points or gates. However, the jump point would need to orbit a planet or the primary star, otherwise the mines would have to thrust constantly in order to remain on station.

Or use solar or magnetic sails to stay in place. Although at that point, you start blurring the line between 'mine' and drone, as said.

[NecronLord]

4. Don't mention Globus Cassus here. Please.

I'm looking at some stuff on this now... And it strikes me as vastly less efficient than building a few Culture Orbitals. If you're going to handwave materials to make a megastructure feisable, why have half measures?

As for defending a whole star system, I'm quite fond of Doc Smith's sunbeam concept. You require a rather fantastical threat to necessitate that, such as he used in his books. You have some mintues' to hours time delay with that, though, so you tend to require your enemy to not be particularly swift. Of course, if they can't see it coming...

[Luzifer's right hand]

I thought the Globus Cassus design is art? Afaik the creator wanted to make something completely unfeasible.

You could use FTL with choke-point or technology which forces ships out of FTL flight if you want to use mines. Or place the mines itself in the medium used for FTL flight if the it's like Transwarp conduits for example.