Asteroid to come close but won’t hit Earth
Print Edition
A house-size asteroid will give Earth a near-miss tomorrow, passing harmlessly inside the moon’s orbit while giving experts a rare chance to rehearse for a real-life strike threat.
Dubbed 2012 TC4, the space rock will shave past at an altitude of less than 44,000 kilometers — just above the 36,000km plane at which hundreds of geosynchronous satellites orbit the Earth.
That represents about an eighth of the distance between the Earth and the moon.
NASA’s Mike Kelley, who leads the exercise to spot, track and intimately probe the transient visitor, insisted there was “no danger. Not even for satellites.”
“We’ve now been observing TC4 for two months, so we have very accurate position information on it, which in turn allows very precise calculations of its orbit,” which will not cross that of Earth nor its satellites, he said.
The object was first spotted five years ago when it called on Earth at about double tomorrow’s projected distance, before disappearing from view.
It is 15-30 meters wide — about the size of the meteoroid that exploded in the atmosphere over Chelyabinsk in central Russia in 2013 with 30 times the kinetic energy of the atomic bomb dropped on Hiroshima. The resulting shock wave blew out the windows of nearly 5,000 buildings and injured more than 1,200 people.
While the Chelyabinsk event caught everyone unawares, TC4 is one of thousands of space rocks whose whereabouts are known. Millions are not.
On its 609-day loop around the Sun, TC4 will return to Earth in 2050 and 2079, according to Ruediger Jehn of the European Space Agency’s Near-Earth Object program. “We know today that it will also not hit the Earth in the year 2050, but the close fly-by in 2050 might deflect the asteroid such that it could hit the Earth in the year 2079.”
With a one-in-750 chance of hitting the planet then, TC4 is listed at No. 13 on the “risk list” of objects posing even the remotest impact risk.
TC4 has been chosen to test the global asteroid pre-warning system, fed by a network of observatories, universities and labs around the world.
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