I may be mistaken somewhere, but to me the implication is that anti-missile defense should be much cheaper than ICBMs. If you send a flak projectile to meet an incoming nuke, and some of the flak fragments produce that type of damage, the reentry vehicle will be ripped apart when entering the atmosphere. The flak projectile does not need to travel intercontinental distances, so it most likely can be launched with a single stage rocket, making it infinitely cheaper than a two-stage ICBM.
Yes, hitting a 15,000 mph ICBM warhead, with a 15,000 mph pellet of tiny 0.5 oz plastic you shot out of a cannon from 5,000 miles away, would be enough to disable it. The roadblock here is hiring a good sniper in this economy. Everyone they hired missed.
Not at all. They are regularly testing interceptors, and more often then not they hit (e.g. test from December '23 [1]) And they don't use flak (an exploding projectile that produces a small cloud of shrapnel), they use a solid kill vehicle, so they achieve the proverbial bullet on bullet thing.
The comment I replied to appears to have completely changed. I replied to a comment that, at face value, asked why don't we shoot 0.5 plastic pellets 5000 miles. Must be a glitch. So ignore my comment, it was in reply to someone else.
1/2*(0.5oz)*(15000mph)^2 = 319 kilojoules of (kinetic) energy
1/2*(1,955 lbs)*(60mph)^2 = 319 kilojoules of (kinetic) energy
So it's basically the same amount of energy as a car at highway speed. But, you'd need to concentrate all of the mass as a small point in order to cause that sort of hole.
Energy of the impact scales with mass, and the square of their (relative) velocity.
So yeah, size matters. But if speed is high enough, even pea sized objects can do enormous damage. Not to mention if said object has an astronaut in its trajectory.
This was actually a political campaign point at the end of the cold war. Congress considered funding low mass by very high speed kinetic weapons in orbit called "rods from God" and "brilliant pebbles".
The link is a forum post with barely any info, followed by a hundreds people commenting. They didn't technically say the experiment occurred in space (it didn't). But the gist is accurate. Here's a better sourced photo with a detailed caption for a very similar experiment https://en.wikipedia.org/wiki/Light-gas_gun#/media/File:SDIO...
It depends on the mass of the block and the relative velocities of both (and thus impact velocity). Which means the effect ranges from *plink* to *kablamo*. In some cases even *kablorch* as both are converted to plasma.
