Near-Earth Objects Workshops to Assess Reconnaissance for Planetary Defense: Working Groups Final Report

Planetary defense against hazardous asteroid and comet impacts on Earth is a growing applied planetary science field with the aims of understanding the nature of near-Earth objects (NEOs), assessing the hazards and opportunities they present to us, and developing operational capabilities for defending ourselves by preventing NEO impacts on Earth. The consequences of NEO impacts can range from harmless meteorite falls; to catastrophic damage to metropolitan areas; to extensive regional devastation; to even extinction level events. With the smaller sized objects vastly outnumbering the larger ones, the most likely impact hazard at any given time is a small NEO that is still large enough to penetrate deeply enough into our atmosphere to deliver harmful amounts of energy to the ground. The most difficult of those to defend against are the smallest that are still large enough to be harmful, because those will also generally be the most difficult to detect far enough in advance to take effective defensive actions. Additionally, smaller NEOs are much more challenging targets for spacecraft navigation systems and measurement instruments than are larger NEOs.