Close asteroid fly-by will help test planetary defence capabilities

The asteroid, which is between 10 and 30m across, will fly close to the Earth on 12th October. Although NASA’s astronomers are certain it will not hit the planet — unlike the slightly smaller rock that burned up in the atmosphere over Chelyabinsk in Russia in 2013 — they do not yet know exactly how close the body’s orbit will bring it to us; their only certainty is that the distance will be between 6800km and 270,000km from Earth's surface.

Usually, close asteroid approaches such as this are used to gather data to characterise them, but in this case researchers at NASA and the Jet Propulsion Laboratory will also test the equipment and procedures that would be used in case of an unexpected and potentially catastrophic heavenly body encounter.

"This is the perfect target for such an exercise because while we know the orbit of 2012 TC4 well enough to be absolutely certain it will not impact Earth, we haven't established its exact path just yet," said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL. "It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible."

2012 TC4 was first discovered on 5 October 2012 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) from Haleakala on the island of Maui, Hawaii, when it passed around 96,000km from the Earth — about a quarter of the distance to the Moon. The telescope tracked the object’s trajectory for seven days, and all predictions about its future movements are derived from those observations. 2012 TC4 has not been seen since, there has been no opportunity to refine the predictions of its trajectory.

“We are using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat," said Michael Kelley, program scientist and NASA Headquarters lead for the TC4 observation campaign.

The effort involves a dozen observatories, labs and universities around the world, explains Vishnu Reddy of University of Arizona's Lunar and Planetary Laboratory in Tucson, who leads the campaign to reacquire 2012 TC4.

"This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications." Chodas added.