Brainstorming a “Kitchen Sink“ Sci-Fi campaign

[Zardnaar]

I know this - reaction drives and guidance. It's pretty obvious when you're doing this, as an asteroid big enough to be a dinosaur killer needs a large drive and a naughty word-load of reaction mass to move it in any reasonable length of time. Unless you can accelerate it to velocities in the 1,000's of km/sec it will still take months or years to get to an inner planet from the outer system.

If you've ever done an orbital rendezvous in Kerbal Space Program, hitting the sphere of influence of a planet, let alone the planet itself is not a trivial undertaking from (say) Jool to Kerbin. The asteroid will still need terminal guidance or a very precise initial shove indeed to hit the target. Caught far enough out, it doesn't need a big push to make it miss - a difference of a few metres per second will do it from far enough out. You have to defend the asteroids or the target will pick up on it and nudge it away.

You need a lot more delta-V to orchestrate the attacks then you need to defend against them. Unless the target has no spacegoing capability or lacks the technology to do the intercept then it's easier to defend this than attack with it.

Clever asteroid trick used in the Thrawn Trilogy. Use the as siege weapons.

You load a few onto star destroyers and put cloaking devices on them. They made you blind as well but doesn't matter on asteroids.

Drop 20 of them around a planet and fake fire your tractor beams a few hundred times.

Don't even need asteroids you could use large tungsten rods or go the mass effect route and fire things very fast.

If you've got ftl drives and interstellar flight one would think you can deal with errant asteroids.

Even in sci fi if you can weapon asteroids large enough to wipe out the dinosaurs you're getting into mega engineering levels of sci fi. The dinosaur killer on the smaller scale estimates masses more than a Super Star Destroyer and they're 19 kilometres long.

 

[MarkB]

Clever asteroid trick used in the Thrawn Trilogy. Use the as siege weapons.

You load a few onto star destroyers and put cloaking devices on them. They made you blind as well but doesn't matter on asteroids.

Drop 20 of them around a planet and fake fire your tractor beams a few hundred times.

Don't even need asteroids you could use large tungsten rods or go the mass effect route and fire things very fast.

If you've got ftl drives and interstellar flight one would think you can deal with errant asteroids.

Even in sci fi if you can weapon asteroids large enough to wipe out the dinosaurs you're getting into mega engineering levels of sci fi. The dinosaur killer on the smaller scale estimates masses more than a Super Star Destroyer and they're 19 kilometres long.

In the Expanse novels, terrorists use stolen stealth materials to coat a bunch of asteroids and shunt them into Eath-intersecting orbits. Only one of them gets through, but it's enough to cause a nuclear winter.

 

[Zardnaar]

In the Expanse novels, terrorists use stolen stealth materials to coat a bunch of asteroids and shunt them into Eath-intersecting orbits. Only one of them gets through, but it's enough to cause a nuclear winter.

They weren't trying to destroy the world but block spaceflight. 20 odd asteroids, 200+ fake launches.

Ship takes off collides with cloaked asteroid. Shuts down all space flight.

Extinction level event you need a decent sized asteroid and to hit the right spot. Smaller asteroids/tungsten rods can "nuke" a city.

 

[MarkB]

They weren't trying to destroy the world but block spaceflight. 20 odd asteroids, 200+ fake launches.

Ship takes off collides with cloaked asteroid. Shuts down all space flight.

That's not how I remember it, or we may be talking about different incidents. There was definitely a full-on surface strike followed by global-scale crisis.

 

[Zardnaar]

That's not how I remember it, or we may be talking about different incidents. There was definitely a full-on surface strike followed by global-scale crisis.

One may have fallen out of orbit but the blockade was the primary goal. They didn't want to destroy Coruscant.

If your cloaking devices work like Romulans you don't need to do this.

Assuming you have them.

 

[MarkB]

One may have fallen out of orbit but the blockade was the primary goal. They didn't want to destroy Coruscant.

If your cloaking devices work like Romulans you don't need to do this.

Assuming you have them.

Okay, you're still talking about the Coruscant one. Since you were quoting my comment about the events in The Expanse I thought that was what you were referring to.

 

[Zardnaar]

Okay, you're still talking about the Coruscant one. Since you were quoting my comment about the events in The Expanse I thought that was what you were referring to.

Lol derp crossed wires.

I've watched the TV show and read a bit about the expanse on the wiki.

Sister in law has the books so I'll need to read them. I know the humans go and colonize the galaxy via the gates, Earth becomes irrelevant and the precursors start to matter.

Precursors seem a big sci fi trope turns up everywhere (Expanse, Trek, Mass Effect, Star Gate, Star Wars legends, Halo, etc)

 

[Fenris-77]

What are your thoughts on the size of the actual gates? Smaller diameter gates would limit the size of the ships. If your FTL tech is bulky, those smaller ships would have limited (or no) capacity. That same bulk could also index weapon capabilities. Overall, you'd have lots of capacity for smaller exploration sized-ships to zip about, but the big warships would pretty limited movement-wise, outside of FTL. If actual FTL travel is limited itself by, say, navigation and destination constraints, you can put some nice limits on you 3D sandbox.

 

[Nobby-W]

What are your thoughts on the size of the actual gates? Smaller diameter gates would limit the size of the ships. If your FTL tech is bulky, those smaller ships would have limited (or no) capacity. That same bulk could also index weapon capabilities. Overall, you'd have lots of capacity for smaller exploration sized-ships to zip about, but the big warships would pretty limited movement-wise, outside of FTL. If actual FTL travel is limited itself by, say, navigation and destination constraints, you can put some nice limits on you 3D sandbox.

The ones in The Expanse were about 1,000km across. The Fsherl-Ganni's gates in Schlock Mercenary are smaller than that but still large enough to fly a capital ship through.

 

[Nobby-W]

Even in sci fi if you can weapon asteroids large enough to wipe out the dinosaurs you're getting into mega engineering levels of sci fi. The dinosaur killer on the smaller scale estimates masses more than a Super Star Destroyer and they're 19 kilometres long.

That was my point earlier. An actual dinosaur killer size asteroid needs a lot of energy to get enough delta-V to accelerate it out of the Asteroid belt or trojan orbits. Lugging something big enough to do that insystem, and then doing the burn isn't going to be subtle. Even a burn to get it into a minimal energy orbit to intersect with your target planet is going to be pretty hard to overlook.

The minimal estimated size for the Chixulub impactor is about 2x10**12 tons. A minimal Jupiter-Earth transfer is about 3.1km/sec worth of delta-V, and that's an orbit that would take years to make the rendezvous with Earth. Even with a 100% efficient reaction drive, that's about 1.5x10**22J of energy, or equivalent to the explosive yield of 3.5x10**6 megatons that you have to somehow conceal while you accelerate the asteroid. Bearing in mind that at a relative velocity of 3km/sec the kinetic energy of an object is roughly equivalent to the explosive yield of its weight in TNT; attempting to sink even 1% waste energy into the object itself is going to make it quite warm.

A city killer could be a lot smaller, but that's some real precision sharpshooting to hit a city-sized target from Jupiter.

Having said this, although I think we now have a sense of the scale of the effort involved in humping dinosaur killers around a star system, we are also in the business of trying to apply real-world physics to a fantastic setting ...