We have orbital predictions for all the asteroids above a certain size, but only a fraction of tens of thousands of smaller bodies entirely sufficient to end ci

We have orbital predictions for all the asteroids above a certain size, but only a fraction of tens of thousands of smaller bodies entirely sufficient to end civilization and very possibly drive us to extinction. One struck the ice sheet in Canada only 12,800 years ago that wiped out 30+ genera in North America including camels, horses, cheetahs, mammoths, mastodons, giant ground sloths, dire wolves, sabertooth cats, a giant beaver, and a giant bear. Their bones, and Clovis spear points, appear only below a thin stratum with massively elevated platinum concentration. Radar is just a matter of putting the right antenna horn on the focal carriage, wired to appropriate gadgetry.