"...we already track everything bigger than a few kilometers.
True! Kachin... ^H^H^H
.oO ...oops, not quick enough to correct /me.
<error horn vibrations ebb>...
Well, actually, only for those cases of "everything" where "everything" includes only the set whose membership is coterminus with the set "those that we happen to know about."
...and each year, astronomers, amateur and career, discover (some .. several) new and previously unknown "rocks" whose orbits CROSS that of the earth. I believe this year's count of such new discoveries, for rocks with radius > 5 km. is already on the order of 3.