Crashing ships as weapons

[mike wightman]

The simplest way to kill pre-jump velocity is as you say to write in a rule to say that a function of the jump procedure is to match your maximum emergent velocity to the escape velocity of the nearest object that matters within the region of the galaxy you are jumping to.

Jump to Jupiter from earth and you arrive 100D out from Jupiter with Jupiter's escape velocity, jump from Neptune to earth's moon and you arrive 100D out with the moons escape velocity.

Jump into 'empty' space within a solar system and you have the escape velocity of the system on jump exit.

Jump to an empty hex and you emerge with galactic escape velocity.

 

[aramis]

What about simply stating that a ship explodes in jump space if it would emerge with over a certain amount of kinetic energy?

There's no scientifically valid way to measure the KE that isn't relative to some specific local frame.

Or you misjump if you try coming in over a certain velocity relative to the nearest planetary mass?

That's more doable, but realize that, if one applies the actual rules (including stars 100 Diameter limits), half a dozen worlds in the marches are 4 weeks round trip from the jump points (any given jump point).

Burning so that you'll come out with a couple days acceleration inbound isn't a bad thing.

Oh, and Marc's noted that Gravitic thrust doesn't work in J-Space, but non-gravitic thrust can be used to generate additional vector while in jump.

 

[BwapTED]

Longer trips to and from jump points could be combined with near-instant jumps to come out to a similar overall trip time.

That is a notable change, though, I'd think.

 

[Grav_Moped]

That changes the TU significantly -- near-instant Jumps mean near-instant interstellar communication. XBoat tenders then have a longer logistics chain, but comms to and from them still only have a lightspeed lag measured in hours.

 

[BwapTED]

That changes the TU significantly -- near-instant Jumps mean near-instant interstellar communication. XBoat tenders then have a longer logistics chain, but comms to and from them still only have a lightspeed lag measured in hours.

Right, which is why I will probably avoid it. Faster comms coinages certain aspects of commerce , piracy, and military actions that I don't know I want to see altered.

 

[mike wightman]

A speed limit on jump exit due to jump physics is still the most elegant solution.

 

[Adam Dray]

I'm no longer convinced that any of this is a problem.

If ten 400-dT ships all appear in a system and start accelerating at max-G towards the home planet, does the planet have sufficient defenses to stop them from colliding at high enough speeds to wreck cities? Not really.

Using the Relativistic Space Calculator (HTML), I get 1.8% c and 14.6 GJ/kg with a 2G acceleration for 10 AU.

That drops to 7.3 GJ/kg at 5 AU, and 1.5 GJ/kg at 1 AU.

That's gigajoules per kilogram. Divide by 4184 for kilotons of TNT.

So at a very conservative estimate of 1000 kg/dT, our 400-dT ship weighs 400,000 kg, giving us explosive ratings like 1400 kT (at 1.8% c). That's easily absorbed by the planet (maybe even the atmosphere).

A 1000-dT ship at 3G acceleration goes up to 22 GJ/kg, or 5258 kT. Not terrible, but I wouldn't want 5 megatons of ship hitting me. It'd be easier to launch nuclear missiles.

 

[MontyLovering]

IMTU standard M drives work using the McGuffin Effect, which is also the basic principle behind anti-grav and J drive.

This works fine and dandy upto 0.2c. Then it stops working. After that you need the use reaction drives. Any planet worth attacking with something considered equivalent to nuclear weapons is going to be able to be able to greet a 0.2c hostile with a lot of missies or a Meson beam. No such thing as stealth in Space.

Of course, it can happen. Occasionally someone mad man will try. But generally wanting to strap reaction drives to a ship gets people asking questions. And if it’s a government thinking of it, the Castlemere incident in 637. In this, the main world of the Castlemere system was destroyed with nuclear weapons by the Imperial Navy for using a relatistic planet smasher to attack a rival world (both were member states of the Imperium).

 

[JimMarn]

I've been thinking about this.

What if an invader tried upsetting the orbits of the comets et al out in the local Oort Cloud ?

Say, by towing a black hole past the rocks and comets out there?

 

[BRJN]

What if an invader tried upsetting the orbits of the comets et al out in the local Oort Cloud ?

If you get the result you want on a militarily significant timescale, then you are trying to conquer a post-Chicxulub-impact world. Surely your blitzkreig will succeed, against bewildered defenders overwhelmed by the natural disaster.

If you don't get the result you want on a significant timescale … there was no point in trying something that difficult and unpredictable.

Either way, at the strategic level, this is likely The Decision That Cost You The War. Everybody else gangs up on you because you are wildly dangerous, like Heath Ledger's Joker. An anti-You alliance of governments forms (maybe as a League of Armed Neutrality, maybe they join whoever you were already fighting), plus civilians in areas you occupy go to productivity 0% due to morale issues.

OTOH if you were one of the AI 'destroy all life' Berzerkers (I don't remember the author of the short stories), it might be a plan to consider.

 

[mike wightman]

If you can steer a black hole to do that why not just fire it at the planet you want to destroy?

 

[JimMarn]

If you get the result you want on a militarily significant timescale, then you are trying to conquer a post-Chicxulub-impact world. Surely your blitzkreig will succeed, against bewildered defenders overwhelmed by the natural disaster.

If you don't get the result you want on a significant timescale … there was no point in trying something that difficult and unpredictable.

Either way, at the strategic level, this is likely The Decision That Cost You The War. Everybody else gangs up on you because you are wildly dangerous, like Heath Ledger's Joker. An anti-You alliance of governments forms (maybe as a League of Armed Neutrality, maybe they join whoever you were already fighting), plus civilians in areas you occupy go to productivity 0% due to morale issues.

OTOH if you were one of the AI 'destroy all life' Berzerkers (I don't remember the author of the short stories), it might be a plan to consider.

Saberhagen I believe wrote the Berzerker stories.

If multiple comets and asteroids hit, I doubt there would be people left. It would depend on why it was being done.

Just to conquer a planet, it would indeed be a waste.

But if something resided on that planet that needed eradicating, then that night be the only way to handle it without significant losses to your own forces.

 

[JimMarn]

If you can steer a black hole to do that why not just fire it at the planet you want to destroy?

It would depend on the desired end result.

If to conquer a planet/solar system, not many should be sent inward.

If the planet had something on it best handled by obliteration, then a direct hit by a black hole would do it. But forces, whatever you were trying to get rid of, managed to get off planet in force, just a black hole might be too slow.

 

[coliver988]

If you can steer a black hole, I am pretty sure you no longer need to destroy a planet through mere physical means...

 

[BwapTED]

I've been thinking about this.

What if an invader tried upsetting the orbits of the comets et al out in the local Oort Cloud ?

Say, by towing a black hole past the rocks and comets out there?

Does a civilization that can tow black holes even bother colonizing planets?

Or are we looking at a TL26 (a guess based on TL charts on the wiki) civilization attacking a TL 12 civilization?

 

[JimMarn]

SF Conquerers just like doing mean things. I had wondered, after I found out about the Oort Cloud, why the Berserkers didn't use such a huge number of asteroids and comets to wipe out non-machine life. But then again, the series would have been rather short as the Berserkers used that tactic in solar system after solar system.

Not much of a defense could be done against large numbers of infalling objects that size.

 

[Condottiere]