NonCredibleDefense

The rods from God's idea is insane and won't work.

We had this back when the Russians announced they were going to drop conventional ordinance from space, and everyone pointed out that they would be lucky to hit the right continent, let alone Ukraine. In order to make this actually work, you would have to have an active aiming system. Which you know, is a missile.

From a purely physical point of view, is that realistic?

If all of its energy is kinetic, it means that the energy must result from it's potential energy+any fuel it is propelled with. Ignoring air-friction and terminal velocity for free falling objects, that means that still the energy of a nuclear weapon is required to bring this thing up into space, or stored as fuel for its propulsion.

So unless the projectile is assembled in space, any rocket bringing it into space will contain at least the energy of a nuclear warhead. Gotta be a very nervous launch, knowing that any failure will result in a fire with the energy of a nuke.

What about the Jewish Space Lasers that MTG said started the wildfires?

If anyone wants some good sci-fi, I recommend The Expanse, both the books and the show. They make great use of kinetic impactors, especially Nemesis Games.

The problem I remember is that it is expensive to get the rod up there in the first place.

Also every other nation would hate us and make jokes about the collective small penis of the US state.

Except you can't just drop it. You need to push it out of orbit, and then push yourself back in

Fun fact, everything with a high velocity (and a certain mass) has a lot of kinetic energy.

(Now think of space ships going light speed. You don't need photon torpedoes)

We should just build space colonies and just drop those when needed

So no one considers moon a weapon of m.ass destruction? All it needs is a fairly good booster on the far side ...

Neil Tyson said this is entirely impractical.

Why in the hell would anyone bother though? First you got to launch all that mass into a stable orbit. Then you got to assemble the delivery system with the mass as it's most definitely too heavy for a single launch. Then you need fuel to deorbit the mass when you launch because things in stable orbits tend to want to stay there. Then you wait for the mass to deorbit because we couldn't afford to send enough fuel for a rapid deorbit. Also wait to launch till optimal trajectory for your target is achieved and hope that it's not too far side to side from your orbital path because that means even more fuel to deorbit. Also anyone with a halfway decent telescope sees your weapon just sitting there in orbit not to mention being assembled so now it's got a massive target painted on it at all times and is an easy casualty of first strike.

Or we could use the icbm's that are a proven tech, easier to hide though that's not foolproof, can be made mobile, much much more numerous, easier to protect from attack, much cheaper than launching tons of solid metal into orbit, and can strike anywhere on the globe within an hour.

Once we have mastered space travel, the most dangerous weapon that will be available to almost anyone will be firing an asteroid at a planet.