Watch Asteroid TC4's Extreme Close Approach With Earth Live Online

An artist's impression of an asteroid. NASA

On October 12, a 50 foot-wide asteroid will skim past Earth at a distance of 31,000 miles. Named TC4, it is one of the closest asteroids to pass Earth this year.

The asteroid is currently travelling at a speed of around nine miles per second. As it makes its flyby of Earth, astronomers are planning to track the close approach from the PanSTARRS observatory in Hawaii. A livestream of the event will begin at 8pm ET. You can watch the broadcast, courtesy of Slooh, below.

The asteroid poses no threat to Earth but it has presented NASA with a rare opportunity to test out its planetary defense systems. TC4 was first discovered in 2012 and, by mapping its orbital trajectory, scientists realized it would be making another flyby of Earth in five years' time.

This gave them plenty of time to plan an exercise testing to test out the protocols they have in place if an asteroid were actually on a collision course with Earth.

Michael Kelley, who leads the TC4 observation campaign, said the close approach is allowing researchers to test out the worldwide asteroid detection and tracking network—allowing different agencies to "work together in response to finding a potential real asteroid threat."

Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory, told Newsweek that he and his colleagues work on the trajectory of the asteroid, plotting out exactly where the asteroid would hit if it was going to.

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Animation depicts the safe flyby of asteroid called 2012 TC4. NASA/JPL-Caltech

"It's a question of refining the position from a corridor down to a footprint of maybe 1,000 kilometers [620 miles], then maybe a few hundred miles," he said. "For TC4, we have just tens of miles of uncertainty and we're still more than a week away. This is exactly what we would do if there were a real case. I would add that this is being used as an exercise for an asteroid impact up through government as well. So NASA headquarters is communicating upwards to the U.S. government."

Initially, scientists had thought that TC4 could return to Earth in 2050, at which point it was on a collision course with Earth. Updated trajectories now show this is not the case. However, if it were it would have given NASA a chance to try out some of its asteroid deflection techniques.

"There are several ways to deflect an asteroid," Chodas said. "The simplest way is to run into it with a fairly massive spacecraft. Running into it at a high velocity would transfer the momentum from the spacecraft to the asteroid and that would change the asteroid's velocity slightly. That would be sufficient to make an asteroid miss Earth if it was done several years, say three to five years, before its potential impact.

"Another is what we call a gravity tractor, which is for a more massive asteroid. This would involve picking up another rock and hovering it over the asteroid. Mutual gravitational attraction over a year or two might be enough to change the velocity. Finally you could fire an ion beam at the asteroid. You would have to fire ions at high velocity…but that should be able to move an asteroid."