Researchers monitoring the trajectory of asteroid 2011 AG5 predict that it will fly safely past and not impact Earth in 2040. Recent space and ground-based observations provided by astronomers and analyzed by NASA's Near Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif., indicate a 99 percent chance of the asteroid missing Earth.
The 460-foot space rock was discovered in January 2011 by the NASA-funded Catalina Sky Survey and put on a "watch list" because its orbit is expected to pass near Earth in 2023.
NASA detects and tracks asteroids and comets passing close to Earth. The Near Earth Object Observation Program plots the orbits of these objects to determine if any could be potentially hazardous to our planet.
Potentially Hazardous Asteroids are based on parameters that measure the asteroid's potential to make threatening close approaches to Earth. Specifically, an asteroid that can pass within 5 million miles of Earth and is about 500 feet in diameter is considered a PHA. These asteroids are large enough to enter Earth's atmosphere intact and cause considerable damage on a local or greater scale. Damage from an asteroid the size of 2011 AG5 could cover an area at least 100 miles wide.
There are currently 1,326 known PHAs, however NASA has just released a new estimate. The data, gathered by an infrared space telescope named WISE, indicate there are roughly 4,700 PHAs plus or minus 1,500 with diameters larger than 330 feet. So far, only 20 to 30 percent of these objects have been found.
Observations of 2011 AG5 next year and in 2016 should give scientists a better understanding of the asteroid's orbit. If the odds of an impact do increase, there will be ample time to plan and carry out at least one of several possible missions to change the asteroid's course.