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Reflection: Near Earth Object (NEO) Hazard, NASA’s Planetary Defense

by Emily Peavy on March 31st, 2017

‘Imiloa invited Rob Landis, Engineer with NASA’s Planetary Science Division, and Dr. Kelly Fast, Program Manager of the Near-Earth Object Observations program in NASA’s Planetary Defense Coordination Office, to the planetarium where they discussed the rocks that have been nudged near Earth’s orbit in their presentation Near-Earth Object (NEO) Hazard: NASA and Planetary Defense.

Raw Ingredients of the Solar System

The presenters described the planets in our solar system as ‘finished’ or ‘well-baked’ as they have collected enough mass to create a round shape and main a cleared stable orbit. If we consider planets in our own solar system as ‘well-baked’ then the asteroids circling planet Earth are the ‘raw’ ingredients which are left over from the formation of our solar system.

Artist depiction of a planet that never quite formed. Image Credit: NASA/JPL-Caltech

Since 1801, we’ve discovered millions of asteroids which are scattered throughout the solar system. Most asteroids orbit between the regions of Mars and Jupiter, in the Main Asteroid Belt. A Near-Earth Object, or NEO, would be any object whose closest approach to the sun is less than 1.3 astronomical units (AU) or 194 million kilometers (km) away (the Earth is 1 AU or 149 million km from the sun on average). While these objects are designated as “Near-Earth,” most of them never come too close to the Earth as they orbit –however NASA’s newly established office, the Planetary Defense Coordination Office (PDCO), is set in place to detect, track and characterize these potential asteroid hazards that are “Near Earth” in order to protect us.


Scientists also consider a sub-set of NEOs which have been designated as Potentially Hazardous Objects, or PHO; these objects will intersect with Earth’s orbit less than 7.5 million km away from our planet.


Search and Detect Program

NASA coordinates with observatories from around the world, one of which includes the University of Hawai‘i’s own Pan-STARRS on Haleakalā, Maui. The Minor Planet Center operates as an international observation database and works to determine the orbit of objects in our solar system. While the Center for NEO Studies, with the Jet Propulsion Laboratory, conducts precision orbit determination and assesses the impact risk with an automated Sentry. When a new NEO or PHO is detected— observatories, including NASA’s Infrared Telescope Facility on Maunakea, will conduct follow up observations to further expand our knowledge of these objects. As of March 4, 2017 15,742 Near-Earth Objects have been detected with 1,788 of them being Potentially Hazardous Objects.

Gif Created from Scott Manley’s video using data from the Lowell Observatory & Minor Planet Center

Explore these types of objects more with JPL’s Keeping an Eye on Space Rocks


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