Planetary Defense

What Is Planetary Defense?

Planetary defense encompasses all the capabilities needed to detect 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 with orbits that bring them into or through a zone between approximately 91 million and 121 million miles (195 million kilometers) from the Sun, meaning that they can pass within about 30 million miles (50 million kilometers) of Earth's orbit. Planetary defense is "applied planetary science" to address the NEO impact hazard.

Planetary Defense Coordination Office

In 2016, NASA established the Planetary Defense Coordination Office (PDCO) to manage its ongoing planetary defense efforts. The PDCO:

  • Provides early detection of potentially hazardous objects (PHOs)—the subset of NEOs whose orbits predict they will come within 5 million miles of Earth's orbit; and of a size large enough (30–50 meters) to cause significant damage on Earth;
  • Tracks and characterizes PHOs and issues warnings of the possible effects of potential impacts;
  • Studies strategies and technologies for mitigating PHO impacts; and
  • Plays a lead role in coordinating U.S. government planning for response to an actual impact threat.*
*Source: https://www.nasa.gov/planetarydefense/overview

How Does DART Fit in?

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 the PDCO. (Credit: NASA)

DAMIEN IWG = Detecting and Mitigating the Impact of Earth-bound Near-Earth Objects Interagency Working Group; FEMA = Federal Emergency Management Agency; IAWN = International Asteroid Warning Network; IRTF = Infrared Telescope Facility; NEOWISE = Near-Earth Object Wide-field Infrared Survey Explorer; PIERWG = Planetary Impact Emergency Response Working Group; SMPAG = Small Missions Planning Advisory Group

For more information about the NEO impact hazard, visit NASA's Planetary Defense page.

Additional information on NASA's planetary defense efforts: