i’m not talking about “dumb bombs” that just fall in a ballistic fashion, beginning at a speed and trajectory equal with the delivery platform (the bomber’s,) gradually nosing down and letting gravity take over. i’m talking about some wacko idea from another forum. assume you can set up the following:
a 10,000-foot tower-tube than can be evacuated into a 2-mile vacuum tube.
you are somehow able to suspend a weight of 1.0 million tonnes at the top of the tower.
you can somehow drop that weight downwards inside the vacuum so it keeps accelerating till it hits the ground.
the energy of the impact is around 30,000 joules compared with the 63,000 joules of the hiroshima bomb (according to the poster.) questions:
what industrial/military application can you think of with this system? (i’ll allow mild sarcasm. you don’t have to remind me it’s crazy.)
you can make it slightly more realistic by digging a 2-mile shaft downwards instead of a 2-mile vacuum tower. the deepest mine shaft i know falls slightly past 1 mile but its diameter allows hoisting of up to 50 tonnes of material at a time. could there be some use to it like say, release tension between two tectonic plates or maybe breach the earth’s crust somewhere to study the moho?
what about a 100m x 100m x 100m slab of granite mountain made to fall on its side? that’s 1 million cu m or 2.6 million tonnes (assuming 2.6 density.) how ‘bad’ could the effects be?
That 2 mile vacuum tube may not be a far fetched as it sounds. Lightning is able to cause a vacuum, perhaps that effect could be used to create a tube for the projectile to fall through.
I suppose there are a variety of contractors [Bechtel and Halliburton] who could think up good reasons [political bribery] for the government to spend [waste] our tax dollars [borrowed Chinese money] on this.
But it allows you to store energy over a long period of time, then release it it very quickly. (Though spinning up a flywheel is probably better - it should allow you to use a smaller mass.)
It sounds like someone trying to duplicate the idea of using asteroids as a weapon, without the asteroid. That’s how you get more energy out of it than you put in - use the Big Rocks that nature has already left scattered about.
Sounds a lot like a project the US has actually thought about (albeit only thought so far, because of treaties and R&D/expenses. Likely more the latter than the former - treaties are just rough guidelines aren’t they ? ). I present to you the Rods from God.
As the article wittily observes, the cost of getting these rods up will be astronomical. A tungsten rod 1 foot in diameter and 20 feet long weighs almost exactly 8 tons. Add some station keeping capability to keep it in orbit and to control the deorbit, and maybe call it 10 tons round figure. That needs a Delta IV medium or a SpaceX Falcon 9 to lift to LEO. SpaceX will tell you how much too, the answer is $55million. A Delta IV will cost significantly over $100million. Nukes might be expensive, but I doubt they are that expensive.
Have you checked the math? For 1M tonnes falling 2 miles, I came up with 31.6 trillion joules.
Wikipedia claims that the Hiroshima bomb had a yield of 13 kilotons, equivalent to 54 trillion joules.
Earthquake generator? Whereas a nuke delivers a lot of thermal energy into the air, this is a thing that would instead deliver a comparable amount of mechanical energy to the ground.
That said, it wouldn’t be a very big earthquake. For falling two miles, the impact speed would be just 562 MPH. For comparison, The meteor that made Metor Crater was estimated to have weighed 0.15 million tonnes at impact, travelling at a speed of 28,600 MPH. In other words, your device would have about 1/400th the energy of that meteor. According to this Richter scale energy equivalence table, your 6.5 kiloton device would produce a quake somewhere between 5.6 and 6.0 (much closer to 5.6). Elsewhere on that page is a description of damage typical for various levels on that scale; a 5.6 can do major damage to crappy buildings, but good buildings will be just fine.
And then of course there’s the practicality of it. To supply 6.5 kT of energy to hoist that million-tonne weight using a typical heavy-duty diesel engine (35% efficiency), you’d need to burn about 750,000 gallons of fuel. Even with the big Wartzila-Sulzer RTA96-C in its 14-cylinder configuration, you’d need to run it continuously for over four days to deliver enough energy to hoist the weight to the top of the drop.
If you want to do damage, you’d be better off dropping a 6.5 kT airburst-nuke.
To address the final idea of making mountains tip over, keep in mind how energy increases in these systems. Kinetic energy is mass times the square of the speed. The fact that the mountain weighs three times as much is insignificant compared to the fact that it will be traveling at a lower speed than the gravity bomb. If we assume the mountain can hit 100 mph, the end result would have less than 10% of the total energy of the gravity bomb.
That’s why orbital weapons like the tungsten rods are a more practical application. The focus is on how to get higher velocity rather than increasingly heavy payloads.
If mountain-tipping was good for anything, it might be useful for creating powerful tsunamis that could take out enemy ports. But we have plenty of good options for that already.
). I present to you the