Relativistic Artillery?

[shadowclasper]

So this was a talk in the chat but it was basically the idea that "Why would anyone have star bases, IE: things in a fixed orbit without the ability to shift that orbit, if you can just chuck a box car sized block of tungsten at the thing from the edge of the solar system moving at a signficant percentage of the speed of light and obliterate it"

You don't even risk a kessler cascade because that much energy from a thing that big moving that fast means it'll leave a cloud of gas behind, no actual debris to cascade.

Now, the obvious reason this can't work is "rule of cool and it's boring to not have star bases". You'd never put anything in orbit with this system that simply couldn't be handled by a large enough star ship. Fixed defenses wouldn't exist, but you would have storage areas, research stations, ship yards, etc. That's still boring though.

But that doesn't provide a logical reason NOT to use this stuff, so to that, it's that anything launched this way is also on a very predictable course, it can be interdicted as well. Sufficiently advanced targetting systems will hit it and remove it. So why use it at all?

Probing attacks.

I'm suggesting that the opening act of just about any invasion of a star system would be to accelerate your space ships up to a certain percentage of C, and then drop a chunk of tungsten or other heavy metals out of a hatch, spun to hit targets you think are installed with defensive capabilities/you don't care if they get blown up.

The reason for this is simple. Even if every single one of these things are hit, they are rediculously cheap to make and fire, because you already have to be getting up to those speeds with FTL interdiction protecting most star systems preventing FTL travel between planets (or just the natural gravity of stars, different articles in the wiki suggested that either of these could be responsible so I dunno). But the people defending the star system MUST intercept, and destroy, this relativistic artillery, or lose a lot of orbital, or even planetary (if you feel like committing war crimes or risk killing an entire planet), assets.

What this means is that this relativistic artillery attack, probably accelerated slightly faster than your own fleet's motion so you can watch the fireworks, will force the defense to reveal at least part of their defensive assets just to stop your attack, giving you better information on what they have to defend the system with.

So the order of operations would be

Step 1: Invaders drop out of FTL inside of the enemy star system
Step 2: Invaders speed themselves up to as significant percentage of C, maybe .15 or .2C
Step 3: Invaders push relativistic artillery rounds out of their ships, and then slow down to just below their own speed. The distances involved mean that even slowing down a little will give them plenty of time to see the results of their attack.
Step 4: Defenders react to artillery, moving assets into place to counter them and revealing their hand, forcing them to commit assets that might have been otherwise held in reserve to deal with the incoming fleet.
Step 4a: Defenders don't move assets into place, and sacrifice orbital assets, reducing moral and increasing cost of war time repairs to infrastructure, hampering ability of defenders to retaliate or continue hostilities.

Good idea? Bad Idea?

 

[Syaoran]

It's not a bad idea but there are some points that might make the plan crumble. Also don't take my word as infallible this is just form what knowledge I have of the star ship mechanics, there are people more informed than me. Such an attack wouldn't always force a response, if it's directly targeting the station for instance, depending on it's shielding and the total energy of the artillery, it might just be able to soak the impact. As for if it can't, most star bases and other orbital defense have very advanced sensory and detection systems as well as way more fire power than they need, so they wouldn't have too much trouble shooting it down and prepping for the on coming fleet. Of course the strategy still has uses, but I think the biggest use would be if for whatever reason you're not able to get a reading on what weapons the defense installments have.

 

[shadowclasper]

Well even just getting a positive ID on any station weaponry would be useful, especially considering the cheepness of such an offensive. I mean, it seems like it would be naturally difficult to get such readings or that bases would go to the effort of trying to camoflage such things from long range detection if only to stop spy traffic from commercial ships from positively IDing the total defenses they have in place?

 

[Syaoran]

Well that's where it gets into stuff I really don't know XD I have no idea how open they are with the information about stations weapons. I mean there are of course special stations with specialized defense, but most seem to come from a stock build, and I don't know how public that info is. It would really depend on the military strategy of the faction. Cause letting everyone know your starbase has a million guns on it can serve as a strong deterrent. So like I said, there is a use for it, I just don't know how much that use will help cause no one really talks about how secret people are with what weapons they have installed.

 

[Wes]

It's possible. The defensive strategies for this are

• Get out of the way (if you're a starship or certain type of space stations)
  
• Divert the incoming projectiles' course (using something like a graviton beam or a gravity well)
• Shoot the things like it's an 80s arcade game
• Use powerful shields to sponge up damage or (gravity/spacial distortion shields are good for solid objects like this)

 

[shadowclasper]

Would a shield even protect against something moving at a significant percentage of the speed of light? I mean I could see a planetary based shield, which could have DRASTICALLY more powerful shields for cities and such probably absorbing or blunting the impact, but what about a space station which has limits on size and materials and fuel and such far lower than a planetary based shield would have?

something moving at .2 the speed of light for example is going to be hideously more energetic than even a fusion bomb, maybe even more so than an antimatter bomb.

edit: asking because I literally don't know if star ship shields can defend successfully against direct hits by antimatter explosives in this setting, if they can then yeah, they can probably shrug this off.

 

[Wes]

The short answer is yes. In Star Army super powerful bombs, and ultra high speed railguns are a thing, and shields have evolved to deal with those. Such shields are going to be found on military battleships, space stations, and around strategically important planets like Yamatai, Nepleslia, or Nataria.

Besides, there's also RP considerations for some planets, which are going to get plot shields.

 

[Syaoran]

It's also worth noting that space stations are pretty big. For instance the OOSY type station by Origin is 40x40x10 all in kilometers so it's got plenty of room to put up a massive shielding system.

 

[shadowclasper]

Ah, if shields can defend against this sorta thing, then yeah, there'd be absolute no point to even probing attacks unless you could accelerate them to almost full C, in which case nothing, not even stars, would be unaffected by the impact of such a thing. Maybe a cool idea for a plot super weapon in the future? But for common usage as a tactic it'd be a waste of resources unless it was a terror attack against a relatively undefended or undeveloped system

 

[Wes]

I should also mention that in the last major war, the NMX used weapons like this regularly.

 

[Fred]

Our setting doesn't tend to give enough respect to newtonian force and the kind of havoc it can cause, especially to ships. We'll have battleship shields able to soak up the damage from a mass driver... which would otherwise be considered a planet cracker. Hence the contrast: ship would survive, planet would not. Directed energy weapons tend to be taken more seriously on top of being considered very accurate, most of the railguns currently in use actually go at a speed that's almost the speed of light and making them slower has been seen as undesirable since ships themselves can commonly move around at 0.3c (something going at .2c isn't likely to hit it), and torpedoes themselves are about as fast but homing (and once, they went as fast as 17 000c to the point we called them Laser+1)

Something like ten years ago, our setting interacted with other forum roleplays, and to compete and come up on top, we commonly tried to grab similar 'good' techs as any other had and +1 them. But it gave us fold speeds that crossed 20 lightyears in minutes, sensors so powerful they could spot tiny things 100 light years away, and weapons like the aforementioned torpedoes that went so fast that you actually couldn't see them coming, and ship combat that could be done at 200 000c somehow.

We've tried - slowly because we didn't want to jar the narrative in ongoing roleplays - to curb things down. Torpedoes are now mostly sublight, ship FTL speeds are slower by a factor of 10, ship sublight speeds went from 0.75c-0.9c down to 0.3c... but we still have uneven values across the board that crop up as not making sense when we try to make them work. But it's still not in a place I'd call 'ideal' (as in, still too perfect); right now, the biggest culprit is probably the sensors. In the meantime of getting more functional fixes, GMs typically just wing it.

 

[shadowclasper]

It's a pity that sensors are FTL at all, because relativistic rules for sensors make for REALLY interesting roleplay and narrative.

If you don't believe me, you should read The Lost Fleet, a semi-hard sci-fi space fiction that was what gave me the idea for proposing this in the first place. The whole interplay of how the speed of light limits when you see events or give orders was a huge part of the narrative and allowed you to do a lot of crazy fun stuff.

That said, I can understand the issues with trying to ramp down a setting from crazy levels to more believable narrative over time. Lord knows I tried to do it with my more mary sue ideas and characters as I evolved as a roleplayer when I was younger but didn't want to scrap them entirely.

 

[Nashoba]

As was said, most starbases and or space stations in the SARP universe have some sort of propulsion even it is just for orbital adjustments. A ballistic weapon the best defense is not be there and most should be able to do just that.

 

[Rhysis]

I want to point out that your enthusiasm in figuring out how things can and would work is fantastic, @shadowclasper . I would like to also, make a suggestion for a character based on what I've seen from you so far. Playing some type of science officer seems like it would go right along with your personality. It takes someone who's willing to put in large amounts of effort into the details of things in order to play one.

 

[Zack]

The word you're looking for is Kirklin Mines. They are about midway down the page near the mass-driver section.

First Law of Space Combat: An object impacting at 3 km/sec delivers kinetic energy equal to its mass in TNT

The hard part is making them connect with the target, which makes them very useful in some situations and not very useful in others. Trying to use it offensively has a lot more complications than using it defensively (which is why they have the term mines in the name). But lets go through your scenario

Step 1: Invaders drop out of FTL inside of the enemy star system

The biggest question here is where they pop out of FTL. The rules always seem to be changing on FTL and I think the rule of thumb is that they have to appear about an hour's worth of travel time outside of the system they want to approach. If we say they only can't jump into a planet's hill sphere then the game changes entirely, but more on that later. You're in space, there is nothing to hide behind, and best case scenario you've been able to jam their FTL sensors. If you appeared ~20 light minutes out that means you have 20 minutes before your target sees you in the best case scenario.

On a side note if the rules at the time limit you to not showing up inside of the hill sphere the enemy has ~15 seconds to react before they are destroyed. If the officer at the Helm isn't paying attention you could easily destroy your target!​

Step 2: Invaders speed themselves up to as significant percentage of C, maybe .15 or .2C

Lets sidestep this issue for now, lets say you have a ship that's fast for SARP, and you're booking it at .33C when you arrive in system. Lets say you did all your acceleration before hand. Either way, the moment the enemy picks you up on sensors they know how fast you're going, how heavy your ship is, and where you are.​

Step 3: Invaders push relativistic artillery rounds out of their ships, and then slow down to just below their own speed. The distances involved mean that even slowing down a little will give them plenty of time to see the results of their attack.
Step 4: Defenders react to artillery, moving assets into place to counter them and revealing their hand, forcing them to commit assets that might have been otherwise held in reserve to deal with the incoming fleet.
Step 4a: Defenders don't move assets into place, and sacrifice orbital assets, reducing moral and increasing cost of war time repairs to infrastructure, hampering ability of defenders to retaliate or continue hostilities.

Lets say you launched your attack right away and slowed down. It'll take 20 minutes for the enemy to detect you, and a full hour for your attack to reach the target. That leaves them 40 minutes to move out of the way. Even a small burst from orbit-keeping thrusters can move a large structure thousands of kilometers so you're going to have to keep launching more Kirklin mines as you approach, absolutely saturate the target system with them, or fire them directly at the planet that can't get out of the way to force the enemy to either body-block or shoot down the mines. This is a very risky proposition because just about every ship in the setting is a planet killer and if you blow up their planet you can be sure that your enemy will respond in kind.

Kirklin mines are dirt cheap, and often are actual dirt. By themselves they aren't going to be much use against a starbase. The normal use is to drop them and let a starship chasing you either run into them, or divert around them which gives you more time to get away. They are also great against dumb-fire weapons which can't maneuver.

Kirklin mines also don't have any ability to maneuver once launched, so the enemy should be able to hit them with point defense weapons near 100% of the time at any range.​

Of course you could greatly improve the results if you added thrusters to your mines... or brought more of them, but building a weapon to defeat a defense is a much larger discussion.