Asteroid 2012 DA14 poses no danger to Earth, says NASA

Asteroid 2012 DA14 will come closer to Earth than any previous object of its size during a Feb 15 fly-by, but the space rock poses no danger to the planet, NASA said.

"No Earth impact is possible," Donald Yeomans, an asteroid expert at NASA's Jet Propulsion Laboratory, in Pasadena, California, told the media.

At its closest approach, DA14 will be 27,300 km from Earth, about a tenth of the distance between here and the Moon.

The asteroid will be traveling 27,700 kph when it careens past the Earth at around 19.40 GMT Friday, according to NASA's Near-Earth Object Program Office, which has been tracking DA14 since it was discovered a year ago by scientists at La Sagra Observatory in Spain.

Though the asteroid is about 13 stories tall, it will not be visible to the naked eye.

DA14 will pass inside the orbits of geosynchronous communications satellites, but far above the altitude of the International Space Station, NASA said.

US astronomers will seek to determine the precise spin of the 2012 DA14 asteroid when it passes the Earth by the smallest-ever recorded margin, the National Radio Astronomy Observatory (NRAO) said.

The direction of an asteroid's spin is an important factor in predicting how the object's orbit will change over time.

The space rock develops a warm region that radiates infrared light providing a gentle but firm jet-like push to it.

The study will help to determine an asteroid's future trajectory and decide whether it poses any threat of colliding with the planet in the foreseeable future.

"Knowing the direction of spin is essential to accurately predicting its future path, and thus determining just how close it will get to Earth in the coming years," said NRAO astronomer Michael Busch.

A team of scientists led by Busch will use the Karl G. Jansky Very Large Array (VLA) and the Very Long Baseline Array (VLBA) antennas at Pie Town and Los Alamos, New Mexico, along with a Solar System radar on NASA's 230-foot antenna at Goldstone, California for their study.

The Goldstone antenna will transmit a powerful beam of radio waves toward the asteroid, and NRAO's New Mexico antennas will receive the waves reflected from the asteroid's surface.

Because of the asteroid's uneven surface and the different reflectivity of portions of the surface, the reflected radar signal will have a characteristic signature, or "speckles", as observed from Earth.

By measuring which antenna in a widely-separated pair receives the speckle pattern first, the astronomers can learn which way the asteroid is spinning, the NRAO said.

An asteroid the size of DA14 approaches the Earth roughly every four decades, while impacts occur at intervals of roughly 1,200 years, Yeomans said.

The most recent significant asteroid impact was in 1908, when a space rock crashed in Tunguska, Siberia. The explosion flattened trees for hundreds of square kilometers.

[link to indiatoday.intoday.in]