The sixth asteroid impact we saw coming

Space security

24/11/2022
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In short

On November 19, the asteroid 2022 WJ1 became one of many small asteroids to hit Earth, but only the sixth we ever saw coming. For the second time this year, mankind predicted an asteroid impact. The roughly 1m rock caused no damage and burned into the sky over Toronto in a striking fireball. The detection, warning and advanced observations of this asteroid illustrate our growing ability to warn of asteroid impacts, no matter how small.

In depth

Sixth Sense

Time-lapse photograph of 2022 WJ1 taken by astronomer Robert Weryk in Ontario, Canada

The initial discovery of asteroid 2022 WJ1 came from the Catalina Sky Survey – one of the major projects dedicated to the discovery and tracking of Near-Earth Objects (NEO) – at 04:53 UTC (05:53 CET) on November 19, 2022, just under four hours before impact.

The new asteroid was first photographed by Catalina’s 1.5m Mount Lemmon Telescopeand once four sightings were made, they were reported to the Center of minor planets (MPC), 38 minutes after the initial detection, at 05:31 UTC.

These four observations were enough to plot the asteroid’s path across the sky, and within minutes of this “astrometry” being published, ESA’s own internal monitoring software reported that the object was about 20% chances of impact on the Earth, possibly hitting somewhere. in North America within the next two to three hours. Minutes later, other impact monitoring programs also sent out alerts describing a similar scenario.

The first impact corridor calculated by ESA’s Meerkat tool at 05:36 UTC, based on the first observations of asteroid 2022 WJ1

Following potential impact notifications, observers at Catalina and elsewhere in the United States obtained follow-up sightings of the new asteroid. Less than 30 minutes from the initial trigger, the impact was confirmed with excellent precision: the small asteroid, likely less than a meter in diameter, was going to impact somewhere between Lake Erie and Lake Ontario, near from the Canada-US border, around 08:00. :27 UTC (09:27 CET).

Exactly at the predicted time, an asteroid about 1 m away hit the atmosphere, becoming a bright ball of fire above the predicted location. Learn more about this event at ESA’s Near-Earth Object Coordination Center (NEOCC) Internet portal.

Asteroid impact: what is the risk?

Due to the formation of the solar system, small objects are the majority in terms of the total population. It is estimated that there are 40-50 million small asteroids and “only” 1,000 of the larger giant “planet killers”. The rest is somewhere in between.

Infographic: the danger of asteroids explained

We currently know of over 1.1 million asteroids, although there are many more. Of those found, approximately 30,600 travel in an orbit closer to that of the Earth. These are “Near-Earth Asteroids” (NEA).

The reassuring news is that almost all of the giant asteroids have been discovered – over 95% – and none are of concern for the next hundred years. Astronomers tirelessly search for the latest.

Chelyabinsk Asteroid Trail

Small meter-sized asteroids hit Earth every two weeks. They add to our understanding of asteroid populations, fireballs and their composition, but they are not a high priority when it comes to planetary defense because they pose no real danger.

The objects that concern us the most are those “Goldilocks asteroids” that are big enough to do harm if they impact, and there are enough of them out there that we know they will. some time. the infamous Chelyabinsk impact in February 2013 and the Tunguska Impact in June 1908 fall into this category, and when it comes to discovering these asteroids, there is still a lot of work to be done.

Hera at Didymos

This is why the ESA Office of Planetary Defense plans new ground-based telescopes and space missions to improve our asteroid detection capabilities, sending the Mission Hera to the asteroid Dimorphos struck by NASA DART mission testing asteroid deflection, as well as working with the international community to prepare for the scenario in which a larger asteroid is discovered on a collision course.

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