December 23, 2012
Astronomers Give The All Clear – Asteroid Will Not Impact Earth In 2040
redOrbit Staff & Wire Reports - Your Universe Online
A 140 meter diameter asteroid experts once believed had a one in 500 chance of striking the earth no longer presents a significant impact risk, NASA officials have confirmed.Previously, orbital uncertainties meant there could have been a 0.2-percent chance that asteroid 2011 AG5 would collide with the planet in February 2040, prompting the scientific community -- including David Tholen, Richard Wainscoat and Marco Micheli of the University of Hawaii Institute for Astronomy (IFA) -- to continue monitoring its course, the university said in a statement Friday.
Tholen, Wainscoat, and Micheli used the 8-meter Gemini North telescope, located at Mauna Kea, to locate the asteroid on October 20, October 21, and October 27 of this year. The data they collected was reviewed by NASA´s Near-Earth Object (NEO) Program Office at the Jet Propulsion Laboratory (JPL) in Pasadena, California, who declared the chance of an impact 28 years from now had been "eliminated."
"The updated trajectory of 2011 AG5 is not significantly different, but the new observations have reduced the orbit uncertainties by more than a factor of 60, meaning that Earth´s position in February 2040 no longer falls within the range of possible future paths for the asteroid," officials from the Gemini Observatory explained. "With the updated orbit, the asteroid will pass no closer than 890,000 km (550,000 miles, over twice the distance to the moon) in February 2040, the time of the prior potential collision."
Had the asteroid, which had a diameter roughly equal to a pair of football fields, collided with Earth, it would have released approximately 100 megatons worth of energy -- several thousand times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki during World War II, the researchers said. The University of Hawaii researchers used the Gemini Multi-Object Spectrograph to collect their data.
According to the IFA, earlier this year, "NEO Program Office conducted a contingency deflection analysis for the 2040 potential impact of 2011 AG5. Among the findings was that any new observations either in 2012 or in 2013, when the object will be much easier to observe, had a 95 percent likelihood of eliminating the hazard posed by 2011 AG5."
"If the potential for impact had been confirmed the impact odds could have risen as high as 1 in 10, but the May 2012 study found that scenario to be unlikely. While the interest in 2011 AG5 has been reduced by the new results, the experience gained by studying this real-world deflection problem has demonstrated that NASA is well situated to detect and predict the trajectories of Earth-threatening asteroids," they added.