Per a report on National Public Radio, inevitably, a large asteroid or comet on the order of 30 to 50 meters in diameter or much, much bigger will smack into Earth. It has happened before. It will happen again. It is only a question of when. Per evidence in the rock record, past collisions from “near-Earth objects” (NEOs) have had planetary impacts that include mass extinctions. Case in point: the end of the dinosaurs 66 million years ago as a result of an immense NEO impact off the Yucatan Peninsula of Mexico.
Papers in the journal Advances in Space Research by Philip Lubin and Alexander “Sasha” Cohen (both of University of California, Santa Barbara) explore two fundamental questions regarding “potentially hazardous objects” (PHOs) and planetary defense.