House-sized asteroid will pass by Earth at just above satellite altitude

Nasa says there will be no danger when the asteroid 2012 TC4 shaves past Earth at merely above the altitude at which most satellites operate on Thursday

A house-size asteroid will give Earth a near-miss on Thursday, giving experts a rare chance to rehearse for a real-life ten-strike threat as it passes inside the moon’s orbit.

Dubbed 2012 TC4, the space rock will shave past at an altitude of less than 44,000 km( 27,300 miles )– only above the 36,000 km aircraft 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 results the exercising to spot, track and closely probe the transient visitor, insisted there was ” no hazard. Not even for spacecrafts “.

” We’ve now been find TC4 for two months, so we have very accurate posture information on it, which in turn allows very precise calculations of its orbit ,” which will not cross that of Earth nor its spacecrafts, he told AFP.

As its name indicates, the object was first spotted five years ago when it called on Globe at about doubled Thursday’s projected distance, before vanishing from view.

It is 15 to 30 metres( 50 to 100ft) broad- about the size of the meteoroid that exploded in the atmosphere over Chelyabinsk in central Russia in 2013, with 30 hours the kinetic energy of the atomic bomb dropped on Hiroshima.

The resulting shockwave blew out the windows of virtually 5,000 houses 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 Rudiger Jehn of the European Space Agency’s Near-Earth Object program in the Netherlands.

” We know today that it will also not make the Globe in the year 2050, but the close flyby in 2050 might deflect the asteroid such that it could hit the Ground in the year 2079 ,” he told AFP by email.

With a one-in-7 50 opportunity of reaching the planet then, TC4 is listed at number 13 on the” risk listing” of objects posing even the remotest impact risk.

” We need to induce very precise observations to be able to better predict the return in the year 2050 ,” Jehn said.

Flybys like this one are actually quite common- about three objects similar in size to TC4 graze past at a similar distance every year.

What makes TC4 special is that it has been chosen to test the global asteroid pre-warning system, fed by a network of observatories, universities and labs around the world.

The asteroid’s close approach will allow teams to evaluate how accurate they were in predicting its orbit and sizing, while using telescopes to learn more about its composition.

” For us this is a test case ,” said Jehn’s colleague Detlef Koschny.” We are practicing for the real serious suit .”

Many scientists believe the Earth will once again be hit by a space stone of the size that wiped out the dinosaurs, though nobody knows when.

And even if they become better at predicting a strike, there is very little to be done about it, for now.

Futuristic projects mooted to deflect or destroy incoming space rocks have come to nought in so far, and the only strategy would be to evacuate people in zones at risk.

TC4 will make its closest approach to Earth just before 05.41 GMT on Thursday, at a point south of Australia, according to ESA and Nasa.

It will not be visible to the naked eye nor with regular binoculars,” but it can be seen in the night of 11 -1 2 October until about 4.00 am from European observatories”, Jehn said.

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