A small asteroid that is expected to fly close to the Earth will provide NASA an opportunity to test its network of observatories and systems for planetary defense, scientists say.

The asteroid 2012 TC4 – estimated to be between 10 and 30 metres in size – will safely fly past Earth on October 12.

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Even though scientists cannot yet predict exactly how close it will approach, they are certain it will come no closer than 6,800 kilometres from the surface of Earth. The asteroid has been out of range of telescopes since 2012.

“Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterise and learn as much as possible about it,” said Michael Kelley, programme scientist and NASA Headquarters lead for the TC4 observation campaign.

“This time we are adding in another layer of effort, 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,” Kelley said.

Professor Vishnu Reddy of the University of Arizona's Lunar and Planetary Laboratory in Tucson leads the campaign to reacquire 2012 TC4 and sees it as an opportunity for the collaborative observation campaign to utilise the international aspect of the network.

“This is a team effort that involves more than a dozen observatories, universities and labs across the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities,” said Reddy.

The goal of the TC4 campaign is to recover, track and characterise 2012 TC4.

“This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications,” Reddy said.

Asteroid 2012 TC4 may be slightly larger than the space rock that hit Earth's atmosphere near Chelyabinsk, Russia, in February 2013.

TC4 has not been seen since its 2012 discovery, when it sped past Earth at about one-fourth the distance from Earth to the moon. It has been too distant and too faint to be detected over the last five years.

As it starts to approach Earth this summer, large telescopes will be used to detect it and re-establish the asteroid's precise trajectory.

The new observations are expected to help refine knowledge about its orbit, narrowing the uncertainty about how far it will be from Earth at its closest approach in October.

“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 NASA's Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in the US.

“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,” said Chodas.