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[Itnetlolor]

He who controls orbital bombardment wins

Especially if you have several cement telephone poles orbiting way up high (with guidance fins, of course). The kinetic force of one of those would hit like a bomb, and wouldn't really require any additional materials to up the magnitude of the strike (gravity alone will do just fine; especially an aerodynamic fall upping the terminal velocity)), not to mention, there wouldn't be anything to salvage besides more concrete and rebar.

Rocks fall, everyone dies.

[misko27]

He who controls orbital bombardment wins

Especially if you have several cement telephone poles orbiting way up high (with guidance fins, of course). The kinetic force of one of those would hit like a bomb, and wouldn't really require any additional materials to up the magnitude of the strike (gravity alone will do just fine; especially an aerodynamic fall upping the terminal velocity)), not to mention, there wouldn't be anything to salvage besides more concrete and rebar.

Rocks fall, everyone dies.

Alright, on one hand, Telephone poles of doom.
 
On the other hand, Giant tar-covered Concrete FISTS of Flaming doom.

[TheBronzePickle]

The tar would burn or slough off too quickly and the ball shape would reduce terminal velocity (as would the tar). Better to stick with God's holy, flaming rock rod raping thy enemies from the heavens.

[Mr Space Cat]

Better to stick with God's holy, flaming rock rod raping thy enemies from the heavens.

Always the classiest tool of choice for megalomaniac conquerors.

[Itnetlolor]

I wonder if a lead/gold-core tungsten rod of death to drop on targets would work better than the above? Or would it be a bunker-buster so heavy and hard, it would collapse mole-people cities?

Talk about raping your enemies; You'll impregnate the earth with this, and it'll give birth to a true Earth-child. Armok.

EDIT:
Depleted uranium would work too. And not just a telephone pole size, but something the size of a rocket booster. We have a MOAB, so why not a FOAB?

[TheBronzePickle]

They should totally use depleted uranium, I think. It's already illegal to field orbital weapons, why bother following any other laws?

[PyroDesu]

Casaba-Howitzer.

Nuclear shaped charge that takes most of the force from the nuclear part and uses it to vaporize a plate of tungsten, ejecting a large plume of tungsten plasma. Supposedly very effective, in theory.

Even worse, the Project Orion (Space drives that use the Casaba-Howitzer charges to propel the thing, well, the other way around, C-H took the drive, but anyways) had some guy at the Air Force design a battleship with it:

Spoiler (click to show/hide)

When the Orion nuclear pulse propulsion concept was being developed, the researchers at General Atomic were interested in an interplanetary research vessel. But the US Air Force was not. They thought the 4,000 ton version of the Orion would be rightsized for an interplanetary warship, armed to the teeth. And when they said armed, they meant ARMED. It had enough nuclear bombs to devastate an entire continent (500 twenty-megaton city-killer warheads), 5-inch Naval cannon turrets, six hypersonic landing boats, and the dreaded Casaba Howitzer, which is basically a ray gun that shoots nuclear flame (the technical term is "nuclear shaped charge").

Keep in mind that this is a realistic design. It could actually be built.

The developers made a scale model of this version, which in hindsight was a big mistake. It had so many weapons on it that it horrified President Kennedy, and helped lead to the cancellation of the entire Orion project. The model (which was the size of a Chevrolet Corvette) was apparently destroyed, and no drawings, specifications or photos have come to light.

[Neonivek]

What about diseases constructed to specifically kill people with certain DNA sequences. So they could kill entirely countries if they wanted to.

[PyroDesu]

What about diseases constructed to specifically kill people with certain DNA sequences. So they could kill entirely countries if they wanted to.

I think that was the premise of Germ, by Robert Liparulo. Genetically engineered Ebola or something tailored to kill one person, and one person only. Everyone else infected just got a cold. Perfect assassination weapon.

[Silfurdreki]

Dunno if it was brought up earlier in the discussion about railguns, but the next class of American supercarrier (the Gerald R. Ford-class) is replacing the traditional steam catapults with a form of railgun for launching aircraft.

Couple of the advantages are that it puts less stress on the airframe; can handle lighter and heavier aircraft than a steam catapult; doesn't require a source of clean, fresh water; and it has a lower overall profile and equipment requirements. It works by using an array of bigass capacitors to store up energy (in the range of 400 MJ+) from the nuclear reactor, then using that in a quick burst to power the linear induction coil. No reason a system like that couldn't be weaponized into a shipboard railgun. If it can accelerate a 100,000lb aircraft up to 130mph, I think it could accelerate a 100lb artillery shell up to signficantly more than that.

½mv², my good man, ½mv². I.e. a 100,000 lb aircraft at 130 mph (yuck, imperial units) is ~1800 m/s for a 100lbs shell, roughly equivalent to current anti-tank sabot weaponry (according to wikipedia). The problem you're facing is that a railgun accelerates linearly, so you'll have a lot less time to accelerate your 100 lbs shell than you have to accelerate your 100,000 lb aircraft (what aircraft is this anyway? For reference, an F16 weighs 26,000 lbs loaded, also accoring to wikipedia). This means you have a higher power requirement which means bigger capacitors and higher currents that are currently not feasible without damaging your railgun.

To me that railgun launcher looks basically like a souped up maglev train rail, which doesn't sound nearly as cool as aicraft railgun, admittedly

Also, on a side note, you don't really need to apply more kinetic energy to pretty much anything, since modern anti-armor guns apply on the order of 1 ev of energy per atom. This energy is on the same order as the typical binding energy of molecules, meaning that they literally atomize what they are shot at. Just a small tidbit of info courtesy of a local astronomy professor, of all things.

_{^{Disclaimer: This might be inaccurate in whole of in part due to some error, it was all made during a 30-minute bored session.}}

[TheBronzePickle]

It would likely be launching F/A-18s of various designation mostly, with E-2 Hawkeyes or fully-loaded EA-6 Prowlers probably being the largest payload they have to send outbound.

[Silfurdreki]

All right, I just picked the first random US fighter I could think of.

The EA-6 Prowler has a weight of 61,500 lbs according to wikipedia, so our 100 lbs railgun slug would have a velocity of 1019 m/s, roughly the speed of rifle bullets.

[RedKing]

I wonder if a lead/gold-core tungsten rod of death to drop on targets would work better than the above? Or would it be a bunker-buster so heavy and hard, it would collapse mole-people cities?

Talk about raping your enemies; You'll impregnate the earth with this, and it'll give birth to a true Earth-child. Armok.

EDIT:
Depleted uranium would work too. And not just a telephone pole size, but something the size of a rocket booster. We have a MOAB, so why not a FOAB?

The good folks at the RAND Corporation did a rather nice monograph on orbital weapons about 10 years ago. Used it as a primary source for a grad paper on space weaponization.

The looked at four main categories: ICBMs, kinetic-energy weapons (your concrete telephone poles), directed-energy weapons (mostly in the context of anti-ICBM defenses), and lobbing very small asteroids. 

Broadly speaking, they recommended tungsten rods for precision strikes. The rod shape causes the impact crater to be more cylindrical than spherical, so you get less collateral damage and more penetration. Tungsten bleeds heat pretty well, though ablation would still be significant.

For example, a 1-m-long tungsten hypervelocity penetrator should be able to penetrate about 1.5 m of steel, almost 3 m of clay or stone, and 1 m of uranium. What penetrates through that depth (or less) of target will be a very hot mixture of target and penetrator material and any remaining penetrator length. The damage is done almost entirely in the direction of the impact, as with a shaped charge explosive, except for damage caused by secondary fires or explosions ignited by the impact.

However, rods are horrible at aerodynamics, which presents an engineering problem. The more spherical, the more even the ablation and the less accuracy and energy you lose due to wobble. But the more rodlike, the more you concentrate your blow into a single deep strike. If you just want to blow shit up indiscriminately, they recommended something of a compromise -- an elongated oblate tungsten spheroid.

Bottom line: dropping tungsten cores from space makes a really nice anti-bunker weapon, not so much a weapon of mass destruction. The projectile loses a lot of kinetic energy to friction and ablation in atmosphere. To get city-busters, you'd have to drop chunks of metal that were already in the kiloton range to begin with. That's where the "lobbing tiny asteroids" part comes in (although ridiculously expensive to find, tow and propel an asteroid...not to mention attempting to impart any kind of accuracy to it)

[RedWarrior0]

Well, it depends on how accurate you want it. If hitting a city is what you want, an asteroid or five works fine.

[RedKing]

Well, it depends on how accurate you want it. If hitting a city is what you want, an asteroid or five works fine.

You'd be surprised. Lobbing an irregularly-shaped hunk of iron and rock (with varying density and composition) and accounting for varying rates of ablation which will change the shape of the asteroid (and thus its aerodynamics) during descent....you could probably aim it at the right country (as long as we're not talking Luxembourg or similar), but you'd be lucky to hit the actual city you're aiming at. However, the massive blast effects probably make up for that.

Ran the numbers for a 1000m-diameter iron asteroid, inserted at 20km/s with 60 degree angle of attack (similar to the parameters RAND uses to assess those tungsten rods):

The impact energy is 8.35 x 1020 Joules = 1.99 x 10⁵ MegaTons.
Final Crater Diameter: 24.5 km ( = 15.2 miles )
Final Crater Depth: 775 meters ( = 2540 feet )
Visible fireball radius: 18.6 km ( = 11.6 miles )


That's kind of big.

Even dropping the size down to half that (500m), changing the density to porous rock, and dropping the speed to 11km/s (basically towing it to the edge of Earth's gravity field and letting it drop unpowered), you get a blast crater 4 miles across and 1/4 mile deep.

Dropping asteroids is kind of a big deal.