Massive asteroid will have close brush with Earth

A close encounter of a dangerous kind.

By Daniel Carrington, The Space Reporter
Tuesday, January 08, 2013

Massive asteroid will have close brush with Earth

It may not seem like it, but Earth is about to have a very close brush with a massive asteroid.

According to NASA, a 275-meter-wide asteroid will make the latest in a series of close approaches to the Earth early Wednesday morning. NASA astronomers say a team of scientists will use the close encounter to further calculate the odds of an impact with Earth fifteen years from now, which remains relatively low.

“It’s likely that radar astrometry in 2013 will shrink the uncertainties sufficiently to completely rule out an impact in the 2030s,” NASA said in a statement released just days before the scheduled pass. “For all these reasons scientific interest in Apophis is acute and it’s very important to learn as much as we can about this object when it gets close enough for physical observations in late 2012 and early 2013.”

The close encounter will be streamed live by a number of organizations around the world. Beginning early Wednesday, amateur astronomers will have the chance to watch the Slooh Space Camera track it once it moves clear of the Sun’s glare.

“Alone among all these near-Earth asteroids that have passed our way in recent years, Apophis has generated the most concern worldwide because of its extremely close approach in 2029 and potential impact, albeit small, in 2036. We are excited to cover this asteroid live for the general public,” said Slooh president Patrick Paolucci.

Discovered in 2004 by astronomers at the Kitt Peak National Observatory, the massive asteroid was calculated at the time to have a 1 in 45 chance of it hitting the Earth. Tomorrow’s approach is the first in series of close brushes with Earth, according to astronomers. In 2029, Apophis is expected to make an extremely close pass to Earth, brushing past the Earth at a distance of just 30,000 kilometers (18,600 miles) – well within the orbit of communication satellites. While astronomers have ruled out the potential of impact, there is still a small chance of an impact in 2036; the principal source of uncertainty is the acceleration due to the Yarkovsky effect, a non-gravitational effect that is a  unction of the asteroid’s rotation period, pole direction, thermal properties, mass, shape, and dimensions.

The close brush should come as relief for anyone living on Earth. NASA scientists recently calculated the impact of a direct strike from Apophis. According to the study, if  Apophis were to strike the Earth it would generate a blast equivalent to more than 500 megatonnes of TNT. In comparison, the most powerful hydrogen bomb ever detonated, the Soviet Tsar Bomba, released 57 megatonnes. The blast would outdo the 330-foot meteor that exploded in the atmosphere above the Tunguska River in 1908. The asteroid hit Earth with an impact 1,000 times more powerful than the atomic bomb that detonated on Hiroshima, destroying an area the size San Francisco.

That said, the asteroid’s near pass should provide astronomers with an amazing show. Apophis on January 9 will be at a magnitude of 19.7—not bright enough to view through a backyard telescope, but reasonably bright through Slooh telescopes in the Canary Islands, said Slooh’s team of astronomers.

There is another silver lining to the asteroid’s proximity to Earth: a potential manned mission. NASA notes that it is currently studying the possibility of sending astronauts to study the asteroid.

“Due to the proximity of its orbit to Earth, Apophis is being considered as a potential target for both robotic and crewed spacecraft missions,” said the space agency.


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