In early July, the Asteroid Terrestrial-impact Last Alert System, or ATLAS, discovered a potentially hazardous asteroid. This 1,600-foot-across space rock, cataloged as 2020 NK1, was calculated to have a one in 70,000 chance of striking Earth between 2086 and 2101. These early estimates suffered from a lack of data: with a better understanding of this asteroid’s orbit, we might learn the asteroid was never getting near or pin down the year it would try to kill us.

Asteroids are found using optical telescopes that look for their moving position in the sky. Their motion against the stars is enough to rough out what orbit they should be on, but because we can only see their motion in the plane of the sky, there are always going to be limitations. 

To really know what’s going on, astronomers use one of the Earth’s massive radar telescopes. These systems bounce radio waves off the asteroids to determine their shape, rotation, and exact distance. The only catch is that the asteroids can only be analyzed by the likes of the Arecibo Observatory radio telescope and radar when they are within about five million miles of Earth or about 20 Earth-Moon distances. For this potentially dangerous asteroid, this kind of approach would happen on July 30-31, 2020.

While asteroid 2020 NK1 was bearing down on the Earth, Arecibo was being assaulted by Hurricane-turned-Tropical-Storm Isaias. 

According to the University of Central Florida: The observatory shut down to prepare for the storm, and as soon as it passed the team jumped into action to detect and study the asteroid.

Observatory scientist Sean Marshall writes: Fortunately, the storm passed quickly without damage to the telescope or the radar system, and the maintenance and electronics teams were able to activate the telescope from hurricane lockdown in time for the observations.

For 2.5 hours, Arecibo radar imaged 2020 NK1, determining its precise shape, orbit, and motion. During subsequent analysis, it was determined that in 2043, this object will pass within 2.25 million miles of Earth – a distance that keeps it more than nine Moon distances from Earth. We’re safe. This time.

While fighting to get a telescope working the moment a storm abates may seem like extreme behavior when the potential danger is still decades away, right now is when we would need to start taking action if the object had been on a collision course. We have the ability to deflect asteroids with current technology, but all of our processes are slow and require a significant lead time to build the needed spacecraft and give them time to get their jobs done. I’m glad we’re safe from this asteroid, and I’m grateful to the team at Arecibo who rode out the storm at the telescope to get us this data.

More Information

University of Central Florida press release