Back in October 2012, a small (45-100 feet, or 15-30 m) asteroid known as 2012 TC4 had a close encounter with Earth. It passed our planet at a distance only a quarter of that between the Earth and the Moon. On October 12, 2017, this asteroid will make another close flyby of Earth. This encounter will be used by asteroid trackers around the world to test their ability to operate as a coordinated International Asteroid Warning Network.
2012 TC4 appears as a dot at the center of this composite image of 37 individual 50-second exposures obtained with the FORS2 instrument on ESO’s Very Large Telescope in 2012. The asteroid is marked with a circle for a better identification. Image credit: ESO / ESA NEOCC / Olivier Hainaut, ESO / Marco Micheli, ESA / Detlef Koschny, ESA.
2012 TC4 was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) on Hawaii back in 2012. However, it traveled out of the range of asteroid-tracking telescopes shortly after it was discovered.
Based on the observations asteroid trackers were able to make in 2012, they predicted that it should come back into view in the fall of 2017.
Observers with the European Space Agency and the European Southern Observatory were the first to recapture 2012 TC4, in late July 2017, using one of their large 8-m aperture telescopes.
According to the asteroid trackers, 2012 TC4 will fly safely past Earth on October 12 at a distance of about 26,000 miles (42,000 km), or a little over 1/10 the distance from Earth to the Moon.
Its closest approach to our planet will be over Antarctica at 1:40 a.m. EDT (5:40 a.m. GMT, 7:40 a.m. CEST, 10:40 p.m. PDT on October 11).
2012 TC4 poses no risk of impact with Earth. Nonetheless, its close approach to Earth is an opportunity to test the ability of a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.
This test of what has become a global asteroid-impact early-warning system is a volunteer project, conceived and organized by NASA-funded asteroid observers and supported by the NASA Planetary Defense Coordination Office (PDCO).
“Asteroid trackers are using this flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid-impact threat,” explained Dr. Michael Kelley, program scientist and NASA PDCO lead for the 2012 TC4 observation campaign.
“This campaign is a team effort that involves more than a dozen observatories, universities and labs around the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities,” said Dr. Vishnu Reddy, an assistant professor at the University of Arizona’s Lunar and Planetary Laboratory, leader of the 2012 TC4 observation campaign.
“This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications.”
