Planetary defense is the term used to encompass all the capabilities needed to detect the possibility and warn of potential asteroid or comet impacts with Earth, and then either prevent them or mitigate their possible effects. Near-Earth objects (NEOs) are asteroids and comets that orbit the Sun like the planets, but their orbits can bring them into Earth's neighborhood - within 30 million miles of Earth's orbit. Planetary defense is "applied planetary science" to address the NEO impact hazard.
In 2016, NASA established the Planetary Defense Coordination Office (PDCO) to manage its ongoing planetary defense efforts. The PDCO:
DART is one part of NASA's larger planetary defense strategy. The DART mission addresses the "mitigate" component of the overall planetary defense efforts, demonstrating a potential technology for deflecting an asteroid off a predicted impact course with Earth, if such action was warranted. DART is NASA's first spacecraft mission developed to achieve planetary defense objectives and the first mission being flown by NASA's newly formed PDCO.
Planetary Defense Efforts of NASA's Planetary Defense Coordination Office (PDCO), of which the DART mission is one component and the first mission being flown by NASA's PDCO. (Credit: NASA) (IAWN – International Asteroid Warning Network; FEMA – Federal Emergency Management Agency; SMPAG – Small Missions Planning Advisory Group; PIERWG – Planetary Impact Emergency Response Working Group; DAMIEN IWG – Detecting and Mitigating the Impact of Earth-bound Near-Earth Objects Interagency Working Group; NEOWISE - Near-Earth Object Wide-field Infrared Survey Explorer; IRTF – Infrared Telescope Facility)
For more information about the NEO impact hazard, visit NASA's Planetary Defense page.
Additional Information on NASA's Planetary Defense Efforts: