NASA downgrades AG5 asteroid threat -– but we’re not out of the woods yet

A recently concluded NASA workshop has determined that asteroid 2011 AG5 has a very slim chance of hitting the Earth in 2040 –- a 1-in-500 chance to be exact. But scientists say that the possibility of impact could increase substantially after the asteroid's flyby in 2023 when it passes through a very critical "keyhole."

The sudden discovery of 2011 AG5 less than a half-year ago prompted NASA to convene a group of experts at their Goddard Space Flight Center in Greenbelt, Md. The group consisted of an international team of scientists and engineers who gathered together to calculate the exact nature of the threat.

NASA downgrades AG5 asteroid threat -– but we’re not out of the woods yetS

2011 AG5 is no joke. Discovered by the NASA-supported Catalina Sky Survey, it is approximately 460 feet (140 meters) in size. And though it may be classified as a potentially hazardous asteroid (PHA), a subset of the typically larger near-Earth asteroids (NEA), it would cause considerable damage should it strike the Earth. An impact from 2011 AG5 would wreak havoc across a region at least a hundred miles wide as it would hit the Earth with a force of 100 megatons.

NASA's team determined that there is a "slight" chance that AG5 will hit the Earth in 2040. They expressed confidence that in the next four years further analysis of space and ground-based observations will confirm that the likelihood of the asteroid hitting the Earth will remain at less than 1%. As more data comes in about its location, size, and trajectory, the more confident these scientists can be in determining the asteroid's exact intentions.

The next crucial stage for making these measurements, however, won't happen until 2023 when the asteroid will be approximately 1.1-million miles (1.8-million kilometers) from Earth. If the asteroid passes through a 227-mile-wide (365-kilometer) region in space called a keyhole in early February 2023, Earth's gravitational pull could influence its orbital path just enough to bring it back for an impact on February 5, 2040 (mark your calendars). But if the asteroid misses the keyhole, an impact in 2040 will likely not occur.

Researchers at the workshop stated that, given their current understanding of the asteroid's orbit, there's a very remote chance of this keyhole passage even occurring. Their current calculations show a 0.2% chance of impact in 2040 based on its current course. Passage through the keyhole, which is also estimated at 0.2%, would force the scientists to revise their estimates –- quite possibly as high as 10 -15%.

Should it get this bad, NASA has announced that it would be ready to take action, including the use of a kinetic-impactor spacecraft that would hit the asteroid with enough mass and at high velocity to change its trajectory. You can read NASA's entire report here.

Top image via Shutterstock/Yeko Photo Studio. Inset image via NASA.