The Near Earth Object Threat to Earth

Three Steps to Success

	The Lincoln Near-Earth Asteroid Research (LINEAR) survey is one of the most successful NEO search projects to date. Funded by the United States Air Force and operated by the Massachusetts Institute of Technology's Lincoln Laboratory, it has made millions of observations, found hundreds of thousands of minor planets (many several times), and discovered hundreds of NEOs.
	The Catalina Sky Survey and its companion survey, the Siding Spring Survey, both funded by NASA, private funding, and other sources, are currently the most productive surveys at discovering new NEOs.

There are several surveys to find Near Earth Objects (NEOs), including LINEAR (funded by the U.S. Air Force), NEAT (funded by NASA through the Jet Propulsion Laboratory using a telescope on Palomar Mountain), LONEOS (operated by Lowell Observatory), and SpaceWatch and the Catalina Sky Survey / Siding Spring Survey (the latter two are operated by different groups at the University of Arizona), as well as others. These surveys, typically operated by or under the guidance of professional astronomers, are effective at finding these bodies.

To determine if an object is dangerous, three things must happen:

1. The object must be detected as early as possible
2. The object must be followed for a period of days to weeks to obtain enough data to compute an accurate orbit
3. The object's orbit must be computed from available data and a prediction made as to whether the object is likely to hit Earth

The surveys are effective, with varying degrees of success, at finding NEO's. In the past, LINEAR found about 70-80 percent of all NEOs. Currently, the CSS survey is the most productive, as it can reach fainter magnitudes than LINEAR. Data from observers for both discoveries (Step 1 above) and follow-up observations of a previously-discovered object (Step 2 above) are sent to the Minor Planet Center (MPC) in Cambridge, Massachusetts. The MPC was designated by the International Astronomical Union (IAU), the leading international organization of professional astronomers, to be the data center and coordinating body for NEO observations. The MPC has the staff and computers necessary to ingest the incoming data, compute orbits, and assess whether an NEO will strike the Earth. If a candidate appears likely to strike the Earth, the MPC will consult with colleagues at NASA's Jet Propulsion Laboratory and in Italy before making a judgment of this magnitude and importance.

Last modified: January 3, 2008.