Movies that imagine an asteroid or comet catastrophically colliding with Earth always feature a main scene: a lone astronomer discovers a stray piece of space heading toward us, sparking panic and a heightened sense of existential dread as the researcher tells the wider world.
On March 11, life began imitating art. That evening, at the Piszkéstető mountain station at the Konkoli Observatory near Budapest, Krisztián Sárneczky was looking up at the stars. Unhappy with the discovery of 63 near-Earth asteroids throughout his career, he’s been striving to find the 64 – and he has succeeded.
At first, the thing he saw seemed normal. “She wasn’t unusually fast,” Sarniczky said. “It wasn’t unusually bright.” Half an hour later, he noticed, “Her movement was faster. That’s when I realized he was quickly approaching us.”
This might sound like the beginning of a melodramatic disaster movie, but the asteroid was just over 6 feet tall — a not-so-dangerous streak. Sarnicky was overjoyed.
“I’ve dreamed of such a discovery many times,” he said, “but it seemed impossible.”
Not only did he spy on a new asteroid, he discovered an asteroid just before it hit the planet, and only for the fifth time has such a discovery ever been made. The object, later named 2022 EB5, may be harmless, but it ended up being a good test of the tools NASA built to defend our planet and its inhabitants from colliding with a rock more dangerous from space.
One such system, Scout, is software that uses astronomers’ observations of near-Earth objects and works to determine approximately where and when their impacts occur. Within an hour of discovering the 2022 EB5, Sárneczky shared his data and it was quickly analyzed by Scout. Although 2022 EB5 would have hit Earth just two hours after its discovery, the program was able to calculate that it would enter the atmosphere off the east coast of Greenland. And at 5:23 p.m. ET on March 11, it just happened, and it exploded mid-air.
“It was a wonderful hour and a half of my life,” Sarnitsky said.
Although EB5 was tiny, it didn’t require a huge jump in size for an asteroid to become a threat. For example, the 55-foot-high boulders that exploded over the Russian city of Chelyabinsk in 2013 released an explosion equivalent to 470 kilotons of TNT, smashing thousands of windows and injuring 1,200 people. This scout can accurately trace the path of a smaller asteroid, providing a form of reassurance. If spotted long enough, it could at least warn a city facing a Chelyabinsk-like space rock in the future.
It usually takes a few days of observations to confirm the existence and identity of a new asteroid. But if this object turns out to be a small but dangerous space rock about to collide with Earth, deciding to wait for this additional data first could have disastrous results. “That’s why we developed the Scout,” said Davide Farnocchia, a navigation engineer at the Jet Propulsion Laboratory that developed the program, which began work in 2017.
Scout is constantly looking at data published by the Minor Planet Center, a clearinghouse in Cambridge, Massachusetts, that notes discoveries and locations of small space objects. Then Varnokia said, “The program is trying to figure out if something is destined for Earth.”
Sárneczky was the first to discover 2022 EB5 due to skill and luck: he’s an experienced asteroid hunter who by chance was in the right part of the world to see the object on its journey back to Earth. His efficiency allowed Scouts to take off. Within the first hour of making his observations, Sarnitsky processed his images, double-checked the coordinates of the body and sent everything to the Minor Planet Center.
Using 14 observations recorded in 40 minutes by a lone astronomer, Scout correctly predicted the time and location of the 2022 EB5 encounter with Earth’s atmosphere. No one was around to see it, but a weather satellite recorded its last moment: an ephemeral flame that quickly consumed into the night.
This isn’t Scout’s first successful prediction. In 2018, another small asteroid was discovered 8.5 hours before the collision. Scout correctly located his path, which proved useful to meteorite hunters who found twenty remaining fragments at Central Kalahari Game Reserve in Botswana.
This will not be possible for 2022 EB5.
“Unfortunately, they landed in the sea north of Iceland, so we won’t be able to recover the meteorites,” said Paul Chodas, director of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory.
Chodas said we also shouldn’t worry that this asteroid was discovered only two hours before it arrived.
“Small asteroids impact Earth frequently, more than once a year of this size,” he said. And their magnitudes mean that their effects are usually without consequences. “Don’t worry about the little things,” Chodas said.
This Scout continues to prove his welcome value. But it wouldn’t be a relief if this program, or NASA’s Near-Earth Object Observing Systems, spotted a much larger asteroid in our path, because Earth currently lacks ways to protect itself.
There is a global effort underway to change that. Scientists are studying how nuclear weapons can transform or eliminate threatened space rocks. And later this year, the Double Asteroid Redirection Test, a NASA space mission, will collide with an asteroid in an attempt to change its orbit around the sun — a dry race on the day we need to hit an asteroid away from Earth in fact.
But such efforts will mean nothing if we remain unaware of the locations of potentially dangerous asteroids. And in this regard, there are still many unknowns known.
Although scientists suspect that most near-Earth asteroids large enough to cause global destruction have been identified, a handful of them may still be hiding behind the sun.
Of greatest concern are the near-Earth asteroids about 460 feet in diameter, which number in the tens of thousands. They can cause city-flatten explosions “larger than any nuclear test ever conducted,” said Megan Brooke Seal, a planetary defense researcher at Lawrence Livermore National Laboratory. Astronomers estimate that they have now found about half of them.
Even an asteroid hitting Earth at 160 feet “was still a really bad day,” said Brock Seal. One such boulder erupted over Siberia in 1908, flattening 800 square miles of forest. “This energy is still 1,000 times greater than the energy of the Hiroshima explosion.” Perhaps only 9% of NEOs have been observed in this size range.
Fortunately, in the coming years, two new telescopes are likely to help with this task: the giant optical observatory Vera C. Rubin in Chile, and the space-based Near-Earth Object Survey Infrared Observatory. Both are sensitive enough to find up to 90% of these killers 460 feet or greater. “As good as our capabilities are at the moment, we need these next-generation surveys,” Chodas said.
We hope time is on our side. The odds of a city-destroying asteroid hitting Earth are about 1% every century — low, but not comfortably low.
“We don’t know when the next effect will occur,” Chodas said. Will our planetary defense system be fully operational before that dark day?
This article originally appeared in the New York Times.
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