The asteroid, called 2011 AG5, currently has a 1 in 625 chance of hitting the planet on Feb. 5, 2040, according to NASA.
2011 AG5 tops the list objects with the biggest risk of crashing into the Earth. However, experts can't observe the asteroid long enough to make a final decision of the likelihood of an asteroid crash. The current 1 in 625 chance will likely be lowered after further observation, experts said, making it less likely a crash will occur.
Fortunately, this object will be observable from the ground in the 2013-2016 interval, Donald Yeomans, head of the Near-Earth Object Observations Program at NASA's Jet Propulsion Laboratory, told Space.com. There would be time to mount a deflection mission to alter its course before the 2023 keyhole.
A keyhole is a small region of space near Earth where a passing object's path could be altered by a planet's gravity. 2011 AG5 could be put on a collision course with the planet if it passes through a keyhole on a close approach to Earth in 2023.
A deflection mission would be planned if it appears the asteroid will pass through the keyhole.
The prudent course of action is then to wait at least until the 2013 observations are processed before making any preliminary plans for a potential deflection mission, Yeomans said.
If deflection is required, scientists plan either to detonate a nuclear weapon on the surface of the asteroid to blow it apart or to ram the asteroid with a spacecraft to alter its course. The success of either approach is not known.
The European Space Agency plans to test how well crashing a spaceship into the asteroid would work through its Don Quijote program, named after the title character of a Spanish novel. The agency said it plans to send a spacecraft to crash into a small asteroid to study the effects in 2013 or 2015.
Scientists will have the opportunity to track 2011 AG5 next year. Those observations will give a more complete idea of the object's path.
Based on these observations, a more informed assessment can then be made on the need for any type of mitigation, Charles Bolden, NASA administrator, told Space.com. He added that at least seven years is needed to properly form any kind of response plan.
Near-Earth objects (NEOs) like 2011 AG5 are constantly being found. The NASA Authorization Act of 2005 formed the Near-Earth Object Survey program to detect and catalogue NEOs and track the ones that pose a threat. As of Sunday, 8,744 NEOs have been found and 1,290 of them have been classified as potentially hazardous asteroids.