How you could help protect Earth from a direct asteroid hit

By Dr Katie Mack

Published: Friday, 09 December 2022 at 12:00 am

In the film Don’t Look Up, a pair of astronomers serendipitously discover an asteroid on a collision course with the Earth. After thoroughly checking their conclusions, they pass the information on to government authorities who immediately take over and order them to remain silent. While word does eventually get out, it’s only because the astronomers themselves leak the result, not because the government has decided to share the data.

To someone outside astronomy, this might seem like the natural course of events. Obviously, the government would be quick to cover up information so big and dangerous! But those of us working in the field take issue with this plot line. Astronomer Gerald McKeegan of the Chabot Space and Science Center in Oakland told the newspaper SF Gate that “The most glaring mistake is the government cover-up… just completely bogus.” And a meteorite that struck southwest Ontario in November illustrated – in a dramatic and visceral way – that a cover-up couldn’t be further from the truth when actual Earth-pummeling asteroids are found.

On the night of November 18, astronomer David Rankin was using a 1.5-meter telescope in Arizona as part of the Catalina Sky Survey, which searches for comets, asteroids, and near-Earth objects – anything whose path brings it in proximity to the Earth – in the night sky. His observations picked up an object that looked like its estimated path might be bring it in our direction.

Following the usual protocol, he immediately reported the discovery to the Minor Planet Centre (MPC): a database of small Solar System objects, maintained by the International Astronomical Union (IAU), that distributes alerts to astronomers around the world about objects of potential interest. The data in the MPC database is not only open to the world, it’s automatically updated online in real time and posted on the IAU’s Near-Earth Object Confirmation Page.

Once Rankin’s initial entry was published, it became a free-for-all. Monitoring software from the European Space Agency automatically retrieved the data and within a few minutes had calculated a likely trajectory, reporting a 20 per cent chance of Earth impact based on the available numbers.

At the same time, NASA’s Scout impact hazard assessment system fired up and arrived at a similar conclusion: there was a real chance this one could hit. That triggered alerts that were sent out to astronomers around the world – professional and amateur alike – to fire up their telescopes and either rule out an impact or pinpoint the expected touchdown zone.

Within half an hour of the alert, it became clear that the asteroid, now known as 2022 WJ1, was definitely going to hit, and soon. Some of the key data came from members of the Northeast Kansas Amateur Astronomers’ League, a group of volunteers operating out of a small, self-built observatory on the grounds of a high school in a small town outside of Topeka.

Near-Earth object discovery is one of the areas in which amateur-professional collaboration is most valuable. A government-run research observatory can only monitor a small part of the sky at any given time, limited by field of view, weather conditions, and the position of the observatory on the Earth; sometimes they’re bound to be looking in the wrong direction.

While automated surveys run by professionals do discover most comets and asteroids, any moderate-sized telescope with a good view and very patient observers can pick up a tiny dot moving across the sky relative to the background stars, and there is no shortage of dedicated enthusiasts keen to join the effort. The Kansas observers’ website boasts that they have discovered over 600 asteroids “and one of the faintest comets discovered by an amateur.”

By the time these and other observations proved that 2022 WJ1 was indeed barreling toward southwestern Ontario, it was also clear that it was, thankfully, unlikely to cause any damage. Calculations based on the object’s brightness suggested it was probably less than a meter in diameter and therefore could be expected to burn up almost entirely in the atmosphere on its way to the ground.

This determination came with two hours left before impact, so there was ample time to wake up any astronomers in the target region and tell them to look up. A few of those bleary-eyed observers captured spectacular images of a bright green meteor trail shooting across the sky, while a webcam in Toronto caught dramatic video of the meteor streaking past the CN Tower. And while the asteroid did not appear to cause anyone harm, there’s a chance that some fragments of it – maybe even as large as a soccer ball – could be recovered from a search of the estimated impact site.

This wasn’t the first time an asteroid was discovered before its impact: five other objects have been found since the first in 2008, and some have resulted in successful sample collection. As observatories around the world continue to search the skies, we’re sure to continue to find near-Earth objects and see collaboration between major agencies and independent sky-watchers. Public data, automatic alerts, and a culture of data-sharing are essential to making that collaboration work, and to making sure we can keep track of whatever the universe might be throwing at us next.