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Relativistic kill vehicle-help me create one

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Sat, 2011-01-08 16:54

Extrasolar Angel Extrasolar Angel's picture

Relativistic kill vehicle-help me create one

I am thinking of designing a RKV as a super weapon project by one of the EP factions. Now,per the setting- the Titanian Commonwealth has sent a probe to Proxima Centauri that will arrive there in 20 years. So I assume values within significant percentage of light speed are possible. Now what it would take to fire a projectile with a mass of 1 to 10 kg that would have 50% light speed within short amount of time. Could something like controlled anti-matter reaction similiar to concept of Orion pulse drive in contained environment work? Let's say a concealed facility within a small moon functioning as one shot gun? What would be the damage inflicted by such a projectile, say for example on Mars or Phobos?

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Sat, 2011-01-08 18:36

Arenamontanus Arenamontanus's picture

Re: Relativistic kill vehicle-help me create one

Extrasolar Angel wrote:
I am thinking of designing a RKV as a super weapon project by one of the EP factions.

I have a sketch in http://www.eclipsephase.com/firewall-guide-unconventional-weapons

Quote:
Now what it would take to fire a projectile with a mass of 1 to 10 kg that would have 50% light speed within short amount of time. Could something like controlled anti-matter reaction similiar to concept of Orion pulse drive in contained environment work? Let's say a concealed facility within a small moon functioning as one shot gun? What would be the damage inflicted by such a projectile, say for example on Mars or Phobos?

That is exactly my idea. A series of antimatter detonations blasting a projectile at the target at absurdly high speed. It might exist some voodotech allowing railgunlike launches, but I am sceptical (still, consider the launch near the start of Dan Simmons' Illium and the three words "Io flux tube") The damage will be equal to the kinetic energy of the projectile; for 86% lightspeed this is exactly twice the energy embodied in the matter of the projectile. For 99% is is 6 times the mass-energy. The result is of course a big, nuclear boom that will tend to penetrate a fairly long distance into the target. It will be like a shaped nuclear explosion, probably good at disintegrating Phobos and creating a big crater on Mars (the crust is pretty thick, so I doubt it will penetrate to any magma unless it hits smack in a vulnerable spot in Hellas). Firing the weapon will require *more* energy than the projectile booms with. The big benefit is that it is hard to see coming. Unfortunately EP has QE comms, which means that sensors can detect the firing (if they are looking) and report back long before the projectile arrives - but an unexpected attack will be unexpected and impossible to shield. And if you get (say) 8 minutes of warning (1 AU) there might still not be enough time to escape a habitat except as an egocast.

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Sat, 2011-01-08 19:10

It that must no... It that must not be named's picture

Re: Relativistic kill vehicle-help me create one

Well, here's a formula for calculating how much energy a mass in motion releases on impact: http://en.wikipedia.org/wiki/Electromagnetic_projectile_devices_%28ficti... The formula is near the top of the page. While the article is about railguns or mass drivers, it would apply to any moving mass hitting at high speed.

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Sat, 2011-01-08 19:17

Extrasolar Angel Extrasolar Angel's picture

Re: Relativistic kill vehicle-help me create one

This: http://www.kylesconverter.com/Speed-or-Velocity/Light-Speed-to-Meters-pe... and This: http://www.csgnetwork.com/kineticenergycalc.html might be of use Edit: This actually combines both above: http://www.ajdesigner.com/phpenergykenetic/kenetic_energy_equation.php

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Sat, 2011-01-08 19:45

Camillus

Re: Relativistic kill vehicle-help me create one

If my maths is right the energy required to accelerate a 1 kg projectile to 0.5 c is roughly 12.97 petajoules. You could get that from about 144 g of antimatter, assuming a loss of 50% energy during the reaction because of conversion to neutrinos. The energy released on impact would be 11.23 pJ, roughly the equivalent of a 2.7 mt nuclear explosion (the Hiroshima bomb was 15 kt and Tsar, the largest bomb ever detonated was 50 mt). A 10 kg projectile would require 129.72 pJ of energy, needing 1.44 kg of antimatter. It would be the equivalent of detonating a 26.8 mt bomb on the target. Your main problem would be achieving the acceleration required in a short period of time. You would need an asteroid more than 5 km in diameter (anything less and your projectile has to exceed the speed of light in barrel when the gun is fired) and the object would be subject to massive forces. Assuming you used a 20 km asteroid the force experienced by the projectile would be about 764,000 g's as it raced up the barrel at 7,495 km/s.

Sat, 2011-01-08 20:09

icekatze

Re: Relativistic kill vehicle-help me create one

hi hi Suppose someone drilled a bore-hole through a geologically dead planet, would that give you enough rail length?

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Sat, 2011-01-08 21:01

Camillus

Re: Relativistic kill vehicle-help me create one

Well, a 3000 km barrel would result in an acceleration of "only" 49.96 km/s, which is 5093 g's. One thing to bear in mind is how obvious this weapon would be. Everyone would know it had been fired and, since the projectile would only be half way to the target when it's activation was detected it [i]might[/i] be possible to intercept it. At 0.5 c it would cover 1 AU in about 16 minutes 40 seconds (Jupiter to Mars is 3.7 AU, for example, so travel time would be about 62 minutes with 30 minutes of warning before impact).

Sun, 2011-01-09 05:04

Arenamontanus Arenamontanus's picture

Re: Relativistic kill vehicle-help me create one

Camillus wrote:
One thing to bear in mind is how obvious this weapon would be. Everyone would know it had been fired and, since the projectile would only be half way to the target when it's activation was detected it [i]might[/i] be possible to intercept it.

This is why it is likely better to have a faster projectile, besides the extra damage (it goes *way* up as you approach c). Also, the impact gets more focused - the initial fireball will at most spread out 45 degrees from the trajectory when it hits, putting all the energy into a ~35% tighter solid angle. But QE sensors are a good defense. If the major powers spread out tiny sensor stations looking for *big* neutrino bursts and moons/asteroids suddenly vaporising, then they can get warnings minutes to hours ahead. Except that detecting where the weapon is aimed may be hard. Intercepting a small, near c projectile is tough. It is enough to hit it with a few grains of sand to blow it up, but you need to get them in place (preferably far away from you, since the boom will still be moving towards you at near-lightspeed - it needs time to dissipate). Lasers will not have much time to heat the target and have limited range, so it has to be a projectile. So if you don't have *very* exact telemetry and some long-distance railguns near the trajectory you have little chance of stopping it. In fact, the grains of sand shows a problem for RKKS: the projectile might blow up by hitting interplanetary dust if it is unlucky. My solution would be to launch a sequence of projectiles, or rather have the projectile split into a train of smaller bullets in flight. The first might get hit by something and blow up, but then the second will become the new shield, and so on. And when they hit the target, they will each strike into the cavity made by the previous one, adding to the penetration ability. Overall, RKKS is good for penetrating extremely hard targets by surprise. It is not the most energy efficient method: you are going to waste most of your antimatter in accelerating the projectile. If you can just wipe out the target by dumping lots of antimatter on it, go for it. But as a deadly first strike it is pretty good: this is what I would build and aim at Progress if I were a PC-unfriendly power.

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Sun, 2011-01-09 17:37

root

Re: Relativistic kill vehicle-help me create one

root@RKV [hr] I forsee an Exhuman attack with one of these. A Pandora Gate seems like a wonderful way to aim a RKV from another system, and if the installation of the receiving end is the target, then the only warning they get is the Gate hack attempt.

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Sun, 2011-01-09 20:46

#10

Extrasolar Angel Extrasolar Angel's picture

Re: Relativistic kill vehicle-help me create one

Quote:
I forsee an Exhuman attack with one of these

Maybe even Exhuman's fear of making ETI repairs and upkeep systems angry. ETI repair and upkeep systems don't want to get...angry.

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Sun, 2011-01-09 23:57

#11

Rhyx

Re: Relativistic kill vehicle-help me create one

Quote:
A Pandora Gate seems like a wonderful way to aim a RKV from another system, and if the installation of the receiving end is the target, then the only warning they get is the Gate hack attempt.

That's going to be cutting it mighty close if you want the Gate hack to be successful just at the right moment. I'm not saying it won't work but hack true and aim straight. It would be a good way to scrape the Ultimates from the Discord gate however. "Sir we have a gate hack in progress." "Probably those damned exhumans testing our defences again. Ready the reserves." The gate opens long enough to send through the RKD everything is destroyed including the gate itself that begins to immediately reform. Once the Exhumans can make contact again they stem through and control both sides of the gate.

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Mon, 2011-01-10 02:31

#12

Arenamontanus Arenamontanus's picture

Re: Relativistic kill vehicle-help me create one

While RKDs through gates make a very cool weapon, I wonder why those exhumans don't just dump a large amount of antimatter through it?

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Mon, 2011-01-10 13:57

#13

Ataraxzy

Re: Relativistic kill vehicle-help me create one

Arenamontanus wrote:
...preferably far away from you, since the boom will still be moving towards you at near-lightspeed - it needs time to dissipate.

And the faster the projectile, the further away it needs to be. Time dilation is a cruel thing. An explosion that lasts for 10s in the frame of reference of the RKV is going to last 32s in the frame of reference of the victim at 0.95[i]c[/i]. At 0.5[i]c[/i], a 10.00s explosion lasts 11.55s. That's an extra 1.55s travelling at 0.5[i]c[/i]. That's an extra 232,339,155m or 232 Thousand km. In the books, most polities are labeled as monitoring space very closely out to 500k km. Basically, the only defense against an RKV is a sandblaster that accelerates particulate matter @ relativistic velocities. Here's the formula, just plug in any number you like that's less than 1, greater than 0 where X is (that's for fractions of [i]c[/i]) and substitute any amount of time where Y is:

Formula for Relativistic Time Dilation wrote:
Y/(1- .X^2)^(1/2)

To solve it, just toss it in a Google search bar or use Wolfram Alpha. The equation preserves time dimensions, so no need to change it for values of Y in seconds, years, decades or anything else. Here's a link to a site with a nice explanation: http://www.phy.olemiss.edu/HEP/QuarkNet/time.html

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Mon, 2011-01-10 13:56

#14

Ataraxzy

Re: Relativistic kill vehicle-help me create one

Arenamontanus wrote:
While RKDs through gates make a very cool weapon, I wonder why those exhumans don't just dump a large amount of antimatter through it?

Who says that they haven't already tried that? :D

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Mon, 2011-01-10 23:58

#15

root

Re: Relativistic kill vehicle-help me create one

root@RKV [hr]

Arenamontanus wrote:
While RKDs through gates make a very cool weapon, I wonder why those exhumans don't just dump a large amount of antimatter through it?

With the RKV, I guess you don't have to even hack them, just know when a Gate is supposed to be open for a window of time. Sure, you are threading a needle at relativistic speeds across enormous distances, and it would take years to get set up for a shot, but their sensors wouldn't really have time to close the gate between when the first warning comes in and oblivion happens.

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