3 ms·

I dunno, surely you would coast out of the system for a year or two. Once out in the Oort cloud, you can drift and turn quietly with your engines away from the

I dunno, surely you would coast out of the system for a year or two. Once out in the Oort cloud, you can drift and turn quietly with your engines away from the solar system and vanish. Then point your engines away (add a glare shield maybe) and nail it inwards. Even if you get so spotted coming from some angle out of the ecliptic no one is going to be able to catch up considering you're coming straight at them rather than a nice stern chase. Accelerating out to meet you head on only makes it worse (though at 50,000km per second, say, you won't be in range for long no matter how far they go). And even in the books the missiles that killed the Canterbury closed 200,000km in eight minutes. That's nearly 200g and the closing speed would have been 800km/s. They'd go 20 miles in a single frame of the 24fps video of the event. Even 50km/s is not a low speed if your defensive strategy is a machine gun. You have 1 second to go from a dinner plate sized cross section object at 50km to being dead, and if even if you did hit it with a bullet going say 2km/s the other way, which is a very fast bullet, if it was on target before, the bits will still hit you nearly as effectively. In fact, a better missile would disperse into a spray of fine metal pieces a few 10s of km away and be uninterceptible and cover a wider area in car you can try a dodge. Seems to me like combat in the universe would be a lot less close-in dogfights and a lot more long range stealth kills by tiny relativistic bullets. And a lot more plausibly deniable "disappearances" in deep space. And I get it, don't get me wrong, rule of cool and all that. And while we don't have those engines, the approximate same techniques probably apply to any spaceship combat we'll see in the next 100 years. Months of nothing slogging across nothingness then dead in a second out of nowhere. Unless radar really improves and stealth doesn't, I guess. And surface impacts from deep space will make current ICBM concerns seem quaintly sedate, even if we can't get to relativistic speeds.

jltsiren 2y ago
The exact numbers in the books are often inconsistent. In Persepolis Rising, the forces that surround the Tempest form a bubble almost three light seconds across. And railgun rounds take less than a minute to reach the center. My overall impression from the books was that the typical engagement distance is from seconds to tens of seconds at railgun speed (relative to the target), whatever that speed is. Anything beyond that, and random course corrections would make hitting anything with an unguided round effectively impossible, no matter how accurate your weapons are. And if you hit a missile at that distance, the random corrections will probably also get you out of harm's way.
- grues-dinner 2y ago
  Yeah, and my point is, a guided missile capable of multi-G course correction coming in at tens of km per second is very unlikely to be stopped by a machine gun. And you do hit it with a bullet by a miracle, you'll only do so at a range that's means you're in the debris shower, which is all going multiples of times faster than a shaped charge detonation. You certainly won't have time to pirouette about firing multiple guns photogenically while a bunch of missiles and the ship are all in one frame. The missiles seem a lot scarier than the railguns which you actually might be able to dodge given the ranges, as long as you saw the firing happen. Not least because a solid rocket motor actually could do quite a lot of that today.
  - jltsiren 2y ago
    The debris will likely miss due to the evasive maneuvers both the missile and the target did, and due to the lack of thrust after the destruction of the missile. Plus the standard practice seems to be pointing the main engine (with exhaust velocity measured in percent of light speed) at the approaching missiles. To avoid being vaporized, the missiles must be intentionally trying to miss and then do aggressive last-moment maneuvers once they are close enough to the target.

jltsiren 2y ago

The exact numbers in the books are often inconsistent. In Persepolis Rising, the forces that surround the Tempest form a bubble almost three light seconds across. And railgun rounds take less than a minute to reach the center. My overall impression from the books was that the typical engagement distance is from seconds to tens of seconds at railgun speed (relative to the target), whatever that speed is. Anything beyond that, and random course corrections would make hitting anything with an unguided round effectively impossible, no matter how accurate your weapons are. And if you hit a missile at that distance, the random corrections will probably also get you out of harm's way.

grues-dinner 2y ago
Yeah, and my point is, a guided missile capable of multi-G course correction coming in at tens of km per second is very unlikely to be stopped by a machine gun. And you do hit it with a bullet by a miracle, you'll only do so at a range that's means you're in the debris shower, which is all going multiples of times faster than a shaped charge detonation. You certainly won't have time to pirouette about firing multiple guns photogenically while a bunch of missiles and the ship are all in one frame. The missiles seem a lot scarier than the railguns which you actually might be able to dodge given the ranges, as long as you saw the firing happen. Not least because a solid rocket motor actually could do quite a lot of that today.
- jltsiren 2y ago
  The debris will likely miss due to the evasive maneuvers both the missile and the target did, and due to the lack of thrust after the destruction of the missile. Plus the standard practice seems to be pointing the main engine (with exhaust velocity measured in percent of light speed) at the approaching missiles. To avoid being vaporized, the missiles must be intentionally trying to miss and then do aggressive last-moment maneuvers once they are close enough to the target.