![]() Which actually casts a bit of doubt on the familiar image of kinetic missiles, at least for offensive use. Spacecraft with electric drive - which are likely in any setting with regular human interplanetary travel - can be expected to go around ten times faster, give or take, thus delivering a whallop of ~100 Ricks. Your encounter speed will probably be at least that much unless you make an orbit matching burn before the shooting starts. Now, 3 km/s is pretty much the slow end of space speeds. As a rough and ready measure, Ricks = (Vi / 3)^2, where Vi is impact velocity. This is Robinson's First Law, and someone at SFConsim-l duly coined the 'Rick' as a measure of kinetic punch. And kinetic energy goes up with the square of velocity, so an impactor hitting at 100 km/s delivers a whallop equal to about 1000 times its mass in TNT. For comparison, TNT delivers about 4.2 megajoules, meaning that at impact speeds much above 3 km/s a conventional explosive warhead merely adds insult to injury. The basic metric of kinetic weapons is that anything hitting you at 3 km/s - a rock, a throw pillow, whatever - delivers 4.5 megajoules of kinetic energy per kg of mass. But they still haven't caught on in science fiction. At least they were rocket propelled! Current generation ABM technology does use kinetic weapons (kinetic kill vehicles, KKVs, being the favored jargon). It was the 1950s, after all, the age of nuclear hand grenades. Death rays remained far more popular in the early Golden Age, while the rocketpunk era, though more given to missiles, assumed they would carry nukes. And because it came out long, I've split it into two posts.Ĭuriously enough, the first - and often prescient - known attempt to describe Realistic space tactics, by Malcolm Jameson in 1939 (scroll down a couple of screens) did feature kinetic 'mines,' but the idea was not taken up. The remainder of this discussion is about tactical combat between spacecraft, i.e. If you are out to wipe out a planet, just nuke the bejeezus out of it rather than spending months or years deflecting an asteroid. 'Strategic' kinetic bombardment of planets appeared in Heinlein's The Moon is a Harsh Mistress, and has been popular for slagging planets ever since we learned what an asteroid impact did to the dinosaurs. They never appeared in any story I recall reading when I was growing up - in fact, I don't recall ever reading a story that featured kinetics used against enemy spacecraft. So it is a bit surprising that kinetic weapons have played such a minor role in science fiction space battles. ![]()
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