June 15, 2012

Asteroid’s Chances Of Impacting Earth In 2040 Slim

Lee Rannals for

An asteroid about the size of a football stadium may slightly have a chance of impacting Earth in 2040, but new estimates show it's hardly a threat.

The space rock, measuring about 460-feet in size, has a likelihood of missing Earth greater than 99 percent, according to the recent findings by scientists at a May 29 workshop at NASA's Goddard Space Flight Center.

"While there is general consensus there is only a very small chance that we could be dealing with a real impact scenario for this object, we will still be watchful and ready to take further action if additional observations indicate it is warranted," Lindley Johnson, program executive for the Near-Earth Object (NEO) Observation Program at NASA Headquarters in Washington, said in a press release.

Asteroid 2011 AG5 was originally discovered back in January 2011, and its path made scientists speculate whether it could actually impact Earth by 2040.

Several observatories began to monitor the asteroid for nine months before it moved too far away, and grew too faint to see.  Scientists and engineers said at the workshop that they will be able to confidently determine whether the asteroid will miss Earth in the next four years, as more observations are made.

Observations of 2011 AG5 have been limited because of its present location beyond the orbit of Mars and in the daytime sky on the other side of the sun.  Conditions will improve in the fall of 2013, so astronomers will be able to use space- and ground-based telescopes to get a better analysis of the asteroid's path.

By the time the fall of 2013 rolls around, the asteroid will be 91 million miles away from Earth, but will still be viewable in the night sky.

Scientists will get an even clearer picture of the asteroid's trajectory by 2023, when the space rock is about 1.1 million miles away from Earth.  If the asteroid passes through a 227-mile-wide region in space, which is called a keyhole, Earth's gravitational pull could influence 2011 AG5's path just enough to bring it back for an impact on February 5, 2040.

"Given our current understanding of this asteroid's orbit, there is only a very remote chance of this keyhole passage even occurring," Johnson said in a press release.

Although scientists expect the asteroid to flyby safely, they acknowledge that there is a slight chance the odds could rise as a result of observations made between 2013 to 2016.  Even if the odds increase, it will still give scientists plenty of time to carry out several missions to change the asteroid's course.

NASA said that damage from an asteroid the size of 2011 AG5 could cover a region on Earth at least 100 miles wide.

NASA's NEO Program was established in 1998, and coordinates the agency's efforts to detect, track and characterize Earth-approaching near earth objects (NEOs) and comets larger than half a mile in size.  The program searchers for NEOs as small as 2011 AG5.