NASA’s Planetary Defense Coordination Office at NASA HQ

NASA and its partners maintain a watch for Near-Earth Objects (NEOs), asteroids and comets that
pass within Earth’s vicinity, as part of an ongoing effort to discover, catalog, and characterize these
bodies and to determine if any pose an impact threat. NASA’s Planetary Defense Coordination
Office (PDCO) is responsible for:

• Ensuring the early detection of potentially hazardous objects (PHOs) – asteroids and comets
whose orbits are predicted to bring them within 0.05 astronomical units of Earth's orbit; and of
a size large enough to reach Earth’s surface – that is, greater than perhaps 30 to 50 meters;
• Tracking and characterizing PHOs and issuing warnings about potential impacts;
• Providing timely and accurate communications about PHOs; and
• Performing as a lead coordination node in U.S. Government planning for response to an actual
impact threat.

The PDCO collaborates with other U.S. Government agencies, other national and international
agencies, and astronomers around the world. The PDCO also is responsible for facilitating
communications between the science community and the public should any potentially hazardous
NEO be discovered. In addition, the PDCO works closely with the United Nations Office of Outer
Space Affairs and the Committee on the Peaceful Uses of Outer Space to support international
collaborations on Near Earth Objects. The PDCO is NASA’s representative as a leading member
of the International Asteroid Warning Network (IAWN) and the Space Missions Planning
Advisory Group (SMPAG), multinational endeavors endorsed by the United Nations for an
international response to the NEO impact hazard, established and supported by the space-capable
nations. In this paper, we provide an overview of the office’s many and varied planetary defense
efforts.