Re: Coolant [Spaceships]
 

And the odd person does consider that a useful response and burn down the restaurant, shoot it up, etc. It's a feature of the 'real world' setting that we live in. Likewise, if space-drives allow people to recreate the twin towers attack on a grander scale, people in that setting would be aware of it, and might well take precautions against it, especially if it had happened in the past. In a setting where groups of people like your typical PC party can get hold of a ship fairly easily, you can bet it's happened before, and that stopping it is a major consideration for traffic control and defence organisations.

Re: Coolant [Spaceships]
 

If you are considering the destruction of The world, yes. If there are eleven thousand worlds, destroying one of them is well this side of unthinkable.

Besides which, as Fred Brackin points out, destroying a planet is hyperbole. But destroying a city is a very real possibility. And destroying a city with the people in it is

• demonstrably not unthinkable, because I can list ten examples of it being done or earnestly attempted, and
• fully sufficient as an incentive for strict control of the possession, operation, or control of, or access to, Jon's-Law-compliant spacecraft.

If you want PCs jauntering around in private spacecraft like Han Solo or Kirth Gersen, you need either

• spaceships that are somehow not compliant with Jon's Law (which is tough to arrange because a dumb rod merely in low orbit can exceed the explosive scale of the 9/11 aircraft with no magic physics whatsoever),
• a firm convention that the campaign will just never mention OKK or RKK weapons, Jon's Law, terrorists or hackers crashing hijacked spaceships into targets, or anything else that strongly suggests the use of that tactic, nor rate kinetic energy in Rics, or
• a steady trickle of civicidal attempts and incidents, prevented or not from time to time by harsh men/women/small furry creatures from Alpha Centauri making mass-lethal decisions.

Re: Coolant [Spaceships]
 

I think that authorities could act with extreme prejudice. A TL10 SM+20 space station could have a tertiary weapon battery with 30 100 GJ VRF ultraviolet laser turrets to keep the peace (dealing 2d×50 (2) burn damage up to 100,000 miles away and costing $6T). With six of such stations guarding a planet, costing an average of $30T each, you could have complete protection for $180T (67% of the economy of the average TL10 world with 4 billion people). Of course, each station could hold millions of people without difficulty, so they would have their own economies as well.

Re: Coolant [Spaceships]
 

If it doesn't violate conservation of energy, it's pushing on something (you can't violate conservation of momentum without also violating conservation of energy), and while it isn't likely to create near-c rock problems, it's hard to avoid the dropping rocks from orbital altitude problem.

Re: Coolant [Spaceships]
 

You can't conserve energy in all inertial frames without thereby conserving momentum.

Re: Coolant [Spaceships]
 

This bit really seems (recurrently) over-sold on the 'harsh' and 'mass-lethal'.

Blowing the Millennium Falcon into dust-bunnies is arguably harsh (it's a small private warship operating in such a way as to threaten a population center in this scenario so...) but it's not mass-lethal. Most of the time that ship has only two people onboard.

You only get 'shoot down the airliner' drama on the subset of kinetic attack incidents where your civicidal types are able to have their way with a sizable shipload of hostages, rather than just a ship.

Re: Coolant [Spaceships]
 

What?

By the time a spaceship is traveling at any appreciable fraction of c, 'shooting it down' is hardly something you can do, certainly not if you imagine it anywhere equivalent to shooting down an airliner.

If you disable the spaceship completely, it's still the same mass heading in the same direction.

The way to prevent the attack might involve the preemptive use of military means to topple a government or to strike against a terrorist organization inside the borders of another polity.

Re: Coolant [Spaceships]
 

A sand caster missile might be a good option against a RKK weapon. With 30 kg of sand released by an explosive a fraction of a second before impact, a 24cm missile would do horrible things to a RKK weapon (at 10% c, it's payload is the equivalent 6.6 megaton of TNT when hit by the RKK weapon, which would vaporize most spacecraft).

Re: Coolant [Spaceships]
 

Several things here.
A) You probably should look at the context. This is not specifically or primarily about relativistic attacks.

B) Yes, you absolutely can shoot down a relativistic ship. It's really easy, put something of any remotely significant size in front of it and boom. No ship, and the mass is going to spread itself out quite quickly after the high-energy event of collision. Some of it may still spray the planet at c-fractional speed, but vastly less than the original impactor. This does of course require you see it coming, which is why depending on your assumptions r-bombers diving out of interstellar space may be infeasible to defend against, but if the attacker started out as a civilian vessel in-system seeing it well ahead of the attack is not a problem.
But that trick never works, Bullwinkle.

Re: Coolant [Spaceships]
 

I wonder if the remnants would indeed impact the target, considering the target is in motion. An obstacle that is struck by an RKK is going to generate a large explosion, which is going to impart thrust onto the RKK. Said thrust will be only for a moment, but will be of sufficient force to turn the RKK into rubble. If the obstacle impacted the RKK dead-center, the thrust is going to slow it; if it impacted at a bit of an angle, it's going to slow it less but also push it off-course. Either case may well mean that, when the RKK's debris field reaches the planet's orbit, the target planet may well not be there anymore. A path for the RKK that is more tangential to the target's orbit (rather than perpendicular) would undoubtedly give it a better margin for error, but in theory so long as you hit the RKK soon enough, it should outright miss the target.