"In 2016, NASA took on a new responsibility: Planetary Defense Coordination. That event reflected a growing interest in, and concern about, the threat of celestial impacts. In ancient times, the solar system's small bodies -- asteroids and comets -- were sometimes seen as ill omens, warnings from the gods. In modern times, they've come to be seen as the solar system's rubble, leftovers from its formation, but still largely ignored until the late 20th century. Increasingly, they've been seen by scientists as objects worthy of study; by the general public, and the US government, as potential threats to be mitigated; and by space advocates as future resources. This book tells the story of those re-interpretations and NASA's role in them"-- Provided by publisher.