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150-foot asteroid to come very close to Earth tonight

Source : AGENCIES
Last Updated: Fri, Feb 15, 2013 04:56 hrs
asteroid

Florida: A newly discovered asteroid about half the size of a football field will pass nearer to Earth than any other known object of its size tonight,

A 150-foot (45-meter)-wide asteroid will come remarkably close to Earth on Friday night, even closer than high-flying communication and weather satellites. The asteroid would give scientists a rare opportunity to observe it close up.  It will be the nearest known flyby for an object of this size.

But don't worry. Scientists promise the mega rock will be at least 17,100 miles (27,518 kilometers) away when it zips past tonight.



"No Earth impact is possible," Donald Yeomans, manager of NASA's Near-Earth Object program at Jet Propulsion Laboratory in Pasadena, California, said Thursday.

Even the chance of an asteroid-satellite run-in is extremely remote, Yeomans and other scientists noted. A few hundred satellites orbit at 22,300 miles (35,886 kilometers), higher than the asteroid's path, although operators are being warned about the incoming object for tracking purposes.

"No one has raised a red flag, nor will they," Yeomans told reporters. "I certainly don't anticipate any problems whatsoever."

Impossible to see with the naked eye, the asteroid is considered small as these things go. By contrast, the one that took out the dinosaurs 65 million years ago was 6 miles (9.6 kilometers) wide.

Yet Asteroid 2012 DA14, as it's known for its discovery date, still could pack a wallop.

If it impacted Earth - which it won't, scientists were quick to add Thursday - it would release the energy equivalent of 2.4 million tons of TNT and wipe out 750 square miles (1,942 square kilometers). That's what happened in Siberia in 1908, when forest land around the Tunguska River was flattened by a slightly smaller asteroid that exploded about five miles above ground.

The likelihood of something this size striking Earth is once in every 1,200 years. A close, harmless encounter like this is thought to occur every 40 years.

The bulk of the solar system's asteroids are located between the orbits of Mars and Jupiter, and remain stable there for billions of years. Some occasionally pop out, though, into Earth's neighborhood

The closest approach of this one will occur next Friday afternoon, Eastern time, over Indonesia.

There won't be much of a show. The asteroid will zip by at 17,400 mph (28,000 kph). That's roughly eight times faster than a bullet from a high-speed rifle.

The asteroid will be invisible to the naked eye and even with binoculars and telescopes will appear as a small point of light. The prime viewing locations will be in Asia, Australia and eastern Europe.

Observers in the U.S. can pretty much forget it. Astronomers using NASA's deep-space antenna in California's Mojave Desert will have to wait eight hours after the closest approach to capture radar images.

Scientists welcome whatever pictures they get. The asteroid offers a unique opportunity to observe something this big and close, and any new knowledge will help if and when another killer asteroid is headed Earth's way.

The close approach also highlights the need to keep track of what's out there, if for no other reason than to protect the planet.

NASA's current count of near-Earth objects: just short of 10,000, the result of a concentrated effort for the past 15 years. That's thought to represent less than 10 percent of the objects out there.

No one has ruled out a serious Earth impact, although the probability is said to be extremely low.

"We don't have all the money in the world to do this kind of work" for tracking and potentially deflecting asteroids, said Lindley Johnson, an executive with the Near-Earth Object observations program in Washington.

Indeed, when asked about NASA's plans to send astronauts to an asteroid in the decades ahead, as outlined a few years ago by President Barack Obama, Johnson said the space agency is looking at a number of options for human explorations.

One of the more immediate steps, planned for 2016, is the launch of a spacecraft to fly to a much bigger asteroid, collect samples and return them to Earth in 2023.

As for Asteroid 2012 DA14 - discovered last year by astronomers in Spain - scientists suspect it's made of silicate rock, but aren't sure. Its shape and precise size also are mysteries.

What they do know with certainty:

"This object's orbit is so well known that there's no chance of a collision," Yeomans repeated during Thursday's news conference.

Its close approach, in fact, will alter its orbit around the sun in such a way as to keep it out of Earth's neighborhood, at least in the foreseeable future, Yeomans said.

Johnson anticipates no "sky is falling thing" related to next week's flyby.

He and other scientists urged journalists to keep the close encounter in perspective.

"Space rocks hit the Earth's atmosphere on a daily basis. Basketball-size objects come in daily. Volkswagen-size objects come in every couple of weeks," Yeomans said.

The grand total of stuff hitting the atmosphere every day? "About 100 tons," according to Yeoman, though most of it arrives harmlessly as sand-sized particles.

Astronomers to study asteroid during close shave

US astronomers will seek to determine the precise spin of the 2012 DA14 asteroid when it passes the Earth Feb 15 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.

The 45-metre asteroid, known as 2012 DA14, was detected in February 2012 when it was about 4.3 million km away.

On Friday, it will come no closer than 27,650 km to Earth, which is well below the geosynchronous communication and weather satellites.

The asteroid is approximately 45 metres in diameter, has an estimated mass is about 130,000 metric tonnes.

Asteroid flyby could scramble your phone signal


An asteroid due to whizz past the Earth this week could take out vital telecommunications satellites, scientists warn.

They are sure there is no chance of the 45.7 metre wide space rock hitting the planet. However, there is a remote possibility that it could collide with one of more than 100 telecommunication and weather satellites in fixed orbits above the Earth.

The asteroid, 2012 DA14, has been closely tracked since its discovery a year ago, 'The Telegraph' reported. It is predicted to reach its nearest point to the Earth on Friday. Experts have calculated it will stay at least 27,681 km away - easily far enough to be safe, but a very close shave in astronomical terms.

Scientists have never observed such a narrow miss before.

Dr Dan Brown, from Nottingham Trent University, said telecommunication satellites - that ping data between our mobile phones - could be in danger.

Travelling at between 20,000 kph and 30,000 kph, or eight times the speed of a rifle bullet - the asteroid will fly inside the orbits of high geostationary satellites some 35,406 km above the Earth. "These are the satellites that provide us with telecommunications and weather forecasts," said Brown.

"There are loads of them but you're talking about a very big area. It would be very unlucky if a satellite was hit. The asteroid is more likely to hit some space junk, but most of this is only about a centimetre across and the impact won't even be noticed," said Brown.

Through binoculars, the object should be visible as a tiny dot of light crossing the sky.

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