NuttyRob

My first idea with a capsule and the starter SRB's was to put a central booster right under the pod, then place 4 more in symetry around the center. Only fire two perimeter boosters at a time then the final stage is the center...you can get plenty into space this way for bookoo science points on mission one....land safely in the desert and take surface samples. --Nutty

Actually, you are right...it would be significantly more destructive than the analogy I used. But the question is energy transfer. Essentially it would be transferring all the energy through a fairly small (give or take .5 meter at most??) diameter. I think it would be more of the kind of thing like you described, like a bunker buster or buried/hardened silos etc. It just wouldn't make much sense for the energy to transfer out to the order of kilometers wide, total destabilizing of the earth's crust. Though the collateral would not be insignificant, it wouldn't level a city.

To address the satellite positioning question: "How long could one keep a satellite locked on target?" Well, to be honest that wouldn't be necessary at all. We've already agreed that you can't simply "drop" a rod from an orbiting body and have it just drop to the earth. It would require some kind of propulsion to get itself into an impact trajectory. Since the projectile would have to de-orbit on its own, a launching satellite wouldn't need to be directly overhead of any target city. In fact, in a lower than geosynchronous orbit, the satellite would have to "drop" the rod well before getting directly overhead. This would be in order to allow the projectile to de-orbit and reach the surface in time. Because of orbiting speed to a lesser extend planetary rotation, dropping an object directly overhead would cause a scenario where the projectile would not only have to slow its orbital speed to zero, but end up accelerating in retrograde direction to counteract the distance it traveled while slowing down in the prograde direction. That is an awful lot of Delta V capability, and completely unnecessary. A satellite in orbit could easily be maneuvered over a certain location (provided it was between certain lattitudes between north and south poles of the body being orbited.) could remain thereabouts for several minutes depending on the actual range of position the sat would have to be in in order to still launch. A geostationary orbit has two requirements, must have zero inclination to the equator and have a circular orbit of just under 24 hours (like earth's rotation period) then the sat could stay there pretty much indefinitely with only minute corrections. If it were north or south of the equator though, even with the same orbital period as earth's rotation, it would only be over certain parts of the earth (the same parts) once every day for a few minutes. This could be altered so that it was over a new location, but would still only be over said location for a few minutes. I hope I was clear enough, I have a tendency to overstate and restate points. Please feel free to smack me around if I go on too long. --Nutty

I also saw this movie, just the other night. When I saw what they were proposing as the workings of the weapon I laughed and tried explaining to my wife why it was completely ridiculous. In the film, the "bad guy" actually states that the tungsten rod is just "dropped." First, as everyone has agreed so far, any projectile from a satellite in orbit would have to shed its orbital velocity to return to earth. And, being that it is just outside the atmosphere and not already traveling at 100,000 Km/h, such as an asteroid might, the projectile (even a very aerodynamically shaped object) would be slowed to it's terminal velocity, or at least slowing to that speed limit until impact. This means it would hit the ground at perhaps a few hundred miles an hour, so something on the order of a small, very dense plane crashing into the ground nose first would result. Just my best guess. --Nutty edit: I split up the text instead of one long paragraph. Proper forum etiquette.