(a result of the "Pizza Satellite" discussion happening in the Food category)
BigThor contends that "a container big enough to hold an extra-large pizza would have enough kinetic energy on impact to wipe out a couple of square city blocks if something went wrong." Cool. Instead of rigging satellites with nuclear warheads, let'em throw rocks! Rocks with little or no processing, explosive, or motive power of their own. Throw a big handful of BigThor's basketball-sized objects at a capital or other important burg, and watch the ejecta take out what didn't immediately become a crater. Meanwhile the warheads are safe to transport, stable, and scarcely deteriorate over long periods in storage; maintenance costs are minimal. As our ability to compute corrections for air currents, coriolis, and other trajectory-baffling variables improves, we can remove the smart from the smart rock altogether, and put it back in the catapult.-- jplummer, Jul 28 2000 asteroider http://www.halfbakery.com/idea/asteroiderDeployed against other worlds... [egnor, Jul 28 2000, last modified Oct 04 2004] The Last Starfighter http://us.imdb.com/Title?0087597Features a "meteor gun." [centauri, Jul 28 2000, last modified Oct 04 2004] Trouble in Legoland http://www.lego.com...Manager&id=52375507 [not_morrison_rm, Dec 01 2014] Bourton on the water http://www.themodelvillage.com/..shouldn't that be Bourton near, but not on, the water..not like it's effing Venice.. [not_morrison_rm, Dec 01 2014] An old old Idea http://en.wikipedia...Is_a_Harsh_MistressPublished in the mid-1960s, and includes throwing rocks as significant weapons of mass destruction. [Vernon, Dec 01 2014] I've seen this in sci-fi. I imagine some think tank somewhere has done a study as well.
I don't think a basketball at orbital velocity will really "wipe out a couple of city blocks", though.-- egnor, Jul 28 2000 Based on my back-of-an-envelope calculations 1kg of matter at escape velocity (11km/s) has kinetic energy equivilent to about 13 times its own weight in TNT (rating TNT at 4600 kJ/kg). Not really enough to flatten cities unless you start using really big rocks.-- Skinny Rob, Jul 28 2000 Another issue is that explosives aren't just a device for releasing a bunch of energy all at once; they're designed to do so in a way that maximizes damage.
There are lots of different ways to build (conventional) bombs, for example; you can use the energy to propel shrapnel, or create a shock wave, or spread incendiary matter, depending on whether you want to kill people or knock down buildings or start fires. Explosives like TNT are an energy source, but the casing is carefully tuned to deliver that energy in the proper way.
Even nuclear weapons (big blunt energy-release bombs if ever there were any) are often designed to tune how the energy is directed (exaggerating the effects of radiation, or EMP, or the shock wave, or whatever is deemed most "strategic").
So, while the velocity of a meteor is also an energy source, it may be more difficult to "shape" into something that does more than just punching a hole in whatever it hits. (Or maybe not; perhaps it would just launch a new field of "meteor design".)
Anyway, gah. We don't need new offensive weapons...-- egnor, Jul 28 2000 The energy released by a meteorite comes from the kinetic and potential energy it has when it's "up there". I guess I'm missing the point here, but to use meteorites as weapons, you'd have to expend the energy to get the rocks up into orbit in the first place. Or are you intending to "farm" existing meteors?-- Lemon, Jul 31 2000 These rocks would have to be extremly large to make it to the ground without burning up in the atmosphere. Space meteors enter Eath's atmosphere everyday, but most of them burn up.-- loneranger, Aug 05 2000 Psst, McGyver-come here... Change name to Space Catapult. Now if you could just get a Giant Flying Horse to land somewhere in Iraq...-- thumbwax, Aug 06 2000 Oh boy, I've done it now.
For one thing, a basketball-sized rock would weigh much more than 1 kg, assuming it was solid granite. The weight of such an object would be closer to 10 kg- which would pack quite a much bigger wallop than a 1kg rock. Loneranger also has a point- the rocks would have to be larger than basketballs to avoid burning up on reentry, but not much larger, in fact. Given a nickel/iron meteor, which are rare, an object 1 metre in diameter should be big enough to survive reentry. Considering that such an object would still weigh hundreds of pounds after reentry, that's a *lot* of energy to be released on impact.
By Skinny Rob's calculation, a 10 kg, basketball sized meteor would have the equivalent of about 130 kg of TNT. That's a pretty good sized wallop.
Something about the size of a Volkwagen Beetle, at the weight of 1 metric tonne would pack the punch of 13,000 kg of TNT- or roughly speaking, a 14 kiloton nuclear warhead. Now *that* will wipe out a lot more than a city block!
Lemon, the idea would be to use rocks already in orbit. So, I guess one would farm existing meteors as you aid.
Loneranger- the majority of meteors actually do burn up, as you mentioned, but the majority of meteors are also a conglomerate of dirt, rocks, and ice. Solid rock and nickel/iron meteors have much more mass and are less subject to breaking up on reentry.
Such a meteor would liberate a great deal of heat on impact, as well as create a large shock wave as well. The shock wave would probably do most of the damage.
My original idea, incidentally, comes from the concept of a 'mass driver'- a device which is basically a large linear accelerator. Such a device has been used as a weapon in many science fiction stories and programs, including Babylon 5 and Steven Spielberg's Invasion USA. The concept of a basketball-sized meteor wiping out a city block actually comes from the movie Armageddon.-- BigThor, Sep 01 2000 How about sheathing the projectile in a re-entry resistant material (ceramic that NASA uses for the shuttle?). You could also shape it in such a way as to reduce wind resistance.
IIRC most of the damage caused by very large meteors is due to cratering effects. Sufficiently large projectiles (say a mostly intact 1 metric ton object) would exploit this cratering effect making huge holes and spreading melted rock in a large plume from the impact site.-- amadeus, Sep 01 2000 Some form of heat shield would be an added guarantee of making a huge hole. The molten rock would be a bonus, starting several fires as well. I still contend, though, that it takes a lot of energy to simply create a crater, and that energy is going to create one hell of a combined tremor and shock wave.
(Kinda has to in order to make a big crater, no?)-- BigThor, Sep 05 2000 I imagine most of the real difficulty would come in trying to aim the damn things accurately.-- moonmoose, Mar 23 2001 UnaBubba: congrats, you've just reinvented the "smart rock" (predecessor to the "brilliant pebble"). This idea is to have "dumb rocks", though.
The dumb rock idea figures prominently in the book _The Moon is a Harsh Mistress_; I'm surprised nobody's mentioned it yet. Revolutionaries on the Moon use their mass-driver (originally intended for grain shipments?!?) to drop rocks on big, bad, taxing-and-not-representing Earth.-- wiml, Mar 25 2001 The grain shipments were dropped into the ocean and floated there, later picked up by ship. They didn't weigh as much as the rocks later fired at land targets. I believe they had retros as well, while the rocks didn't...
Spin them for gyroscopic stability, and with a bit of 'Kentucky windage' it shouldn't be too hard to hit what you want.-- StarChaser, Mar 25 2001 "Kentucky windage"? Isn't that what you get from eating too much fried chicken too quickly?-- sirrobin, Mar 25 2001 <grin> Yeah, but if you time it right...-- StarChaser, Mar 25 2001 How about space shuttles to Saturns rings and back for the dumb rocks-- sargocs, Apr 16 2001 Didn't the Bugs in Starship Trooper drop an asteroid on Buenos Aires? On a more benign note, why don't we use obsolete military missiles to boost several hundred dump-truck-loads of sand and pea gravel into low orbit and create our own "meteor" shower? (Have to be careful we don't start knocking out satellites, might slow down Internet access and we CERTAINLY don't want that.)-- Dog Ed, Apr 16 2001 Because there's already a huge amount of crap in orbit and it's causing problems...-- StarChaser, Apr 16 2001 Ah, but my pebble proposal would involve orbits low enough that atmospheric drag would quickly (in a matter of days) bring all the faux meteors flaming to Earth, like Mir. No leftover mess, melts in the atmosphere not on your rooftops, good to the last flash.-- Dog Ed, Apr 17 2001 sure, a rock that size would have gobs of kinetic energy, but that doesn't mean the rock will spontaneously explode and wipe out entire city blocks. More likely, it'll put a really deep hole in the ground, or in someones roof.-- tkeyser, Apr 17 2001 Atmospheric friction would burn up your payload-- gorn_the_blastoid, Jul 24 2001 Two examples in the literature: "The man who pulled down the sky" (Book, I've forgotten the author; must be at least 10 years ago). Pretty much exactly as specified - great big bolley (steel ball-bearing); drop from orbit.
Multiple events in the Gundam series' (anime). Space colonies dropped from orbit.
Provided whatever you deliver doesn't slough off or burn up in the atmosphere, all that kinetic energy has to go somewhere. And if nukes can re-enter without burning up, it is certainly possible to wrap a lump of metal appropriately. Of course as other people have mentioned, you have to get the stuff up there to start with - so you must invest an equal amount of energy to lift the thing off the ground. Plus the launcher. Unless you fancy a quick jaunt to the moon (Or even further afield) for a spot of mining (Impractical unless you intend large-scale manufacture)-- Loris, Aug 14 2002 //The man who pulled down the sky// - John Barnes.
I have not read it !-- po, Aug 14 2002 Considering that the rocks that manage to hit earth in "Armagedon" style movies are moving at velocities considered relatavistic compared to anything humans have rocketed into space or eachother, and that acceleration due to gravity is limited to approx 120 mph going straight down from LEO, it wouldn't melt, and it would cause about as much damage as a drunk teen in a corvette. Heres a better idea, fire a large (100 ton) rock from the moon with titan V style boosters on a trajectory that would use planetay gravity to accelerate it and redirect it back to earth at a specific target, and in 25 years, we can declare war against the target for ne reason, and turn it into a crater in a few weeks without drawing attention to any military buildup.-- HMav, Aug 21 2002 Thank you [wiml] for reminding us that Mycroft Holmes thought this up first. I thought no one would mention (in my opinion) Robert Heinlein's greatest work.
It's a great idea, but as Heinlein points out, it's much easier to throw 100 ton rocks off the moon than to boost anything up from earth. Until there are angry people hanging out in Earth orbit, I doubt you would see this sort of thing used in a war.-- discontinuuity, Jul 10 2005 //acceleration due to gravity is limited to approx 120 mph// What? A skydiver hits 120 in just a few thousand feet, and is limited in speed by air resistance.
The thing some people here seem to forget is the balance between energy consumed in throwing upward, and energy delivered in falling back down. Any rock we throw upward will land with no more energy than we expended in throwing it, and probably much less, so we are wasting effort and screwing up the environment.
Think of it a shooting a damned big gun at your target. Would you rather fire pointblank into the side of the target, or shoot straight up and hope for a hit when the bullet comes drifting back down?
If, as was mentioned above, you could use something in space to generate the speed, you might have something of a weapon. But then you'd have greater problems with aiming. This is one of those ideas that has been done to death in science fiction because it is so damn obvious, but hasn't been done in the real world because it is so damn difficult. Someday it will be done, maybe by some band of crazies with a solar sail and a longterm plan, but I'll bet they miss.-- baconbrain, Jul 10 2005 <Needless, pedantic churn> //Something about the size of a Volkwagen Beetle, at the weight of 1 metric tonne would pack the punch of 13,000 kg of TNT- or roughly speaking, a 14 kiloton nuclear warhead. Now *that* will wipe out a lot more than a city block!//
Out by three orders of magnitude. 13000kg of TNT is 13T, which is .013 kilotonnes. So, not very much at all.
</npr>-- Custardguts, Dec 01 2014 Ohh, but just think of what it might do to Legoland....the place'd be levelled. Or Bourton on the Water's model village..
Incidentally, trouble in Legoland, of a sort, Fraud Prevention Manager vacancy for online sales...presumably offenders will inhabit a Lego prison..-- not_morrison_rm, Dec 01 2014 [marked-for-deletion] very widely known to exist in science fiction and airliner waste disposal. See Wikipedia articles for "kinetic bombardment" and "orbital bombardment".-- FlyingToaster, Dec 01 2014 Hmm, just noticed someone's doing annos on Huffington Post in binary..-- not_morrison_rm, Dec 01 2014 <pedant> Since we're using computers, technically ALL the anno's are in binary... </pedant>-- neutrinos_shadow, Dec 02 2014 random, halfbakery