Movies depicting an asteroid or comet catastrophically colliding with Earth always include a key scene: a lone astronomer sees the errant space piece rushing towards us, a lone astronomer sees the errant space piece rush towards us, some panic and a growing feeling of existential anxiety as the researcher tells the wide world.
On March 11, life began to imitate art. That evening, Krisztián Sárneczky looked up at the stars at the Piszkéstető mountain station of the Konkoly Observatory near Budapest. Unhappy with discovering 63 near-Earth asteroids during his career, he was looking for his 64th — and he succeeded.
At first, the object he saw seemed normal. “It wasn’t unusually fast,” said Mr. Sarneczky. “It wasn’t unusually bright.” Half an hour later he noticed that ‘his movement was faster. Then I realized it was fast approaching us.”
That may sound like the start of a melodramatic disaster movie, but the asteroid was just over six feet long — a non-threatening squeak. And Mr Sárneczky felt elated.
“I have often dreamed of such a discovery, but it seemed impossible,” he said.
Not only had he seen a new asteroid, he’d discovered one just before it hit Earth, and only the fifth time such a discovery had ever been made. The object, later named EB5 in 2022, may have been harmless, but it turned out to be a good test of tools NASA built to protect our planet and its inhabitants from a collision with a more menacing rock from space.
One such system, Scout, is software that uses astronomers’ observations of near-Earth objects to calculate approximately where and when their impact might occur. Within the hour of detecting 2022 EB5, Mr. Sárneczky shared his data and it was quickly analyzed by Scout. Although the EB5 would hit Earth just two hours after its discovery in 2022, the software calculated that it would enter the atmosphere off the east coast of Greenland. And at 5:23 p.m. Eastern Time on March 11, it did just that, exploding in the sky.
“It was a wonderful hour and a half in my life,” said Mr. Sarneczky.
While EB5 was lean, it doesn’t take a huge jump in size for an asteroid to become a threat. For example, the 15-meter-high rock that exploded over the Russian city of Chelyabinsk in 2013 caused an explosion equivalent to 470 kilotons of TNT, smashing thousands of windows and injuring 1,200 people. That Scout can precisely plot the orbit of a smaller asteroid provides some reassurance. If caught in time, a city facing a future Chelyabinsk-esque space rock can at least be warned.
It normally takes a few days of observations to confirm the existence and identity of a new asteroid. But if that object turns out to be a small but dangerous space rock about to hit Earth, the decision to wait for that extra data first could have disastrous consequences. “That’s why we developed Scout,” said Davide Farnocchia, a navigation engineer at the Jet Propulsion Laboratory who developed the program, which went live in 2017.
Scout is constantly looking at data posted by the Minor Planet Center, a clearinghouse in Cambridge, Massachusetts, that notes the discoveries and positions of small space objects. Then “the software tries to figure out if something is on its way to Earth,” said Dr. farnocchia.
That Mr. Sárneczky was the first to see 2022 EB5 came down to both skill and luck: he is a skilled asteroid fighter who happened to be in the right part of the world to see the object on its journey to Earth. And his efficiency allowed Scout to get into gear. Within the first hour of his observations, Mr. Sárneczky his images, he checked the coordinates of the object and sent everything to the Minor Planet Center.
Using 14 observations in 40 minutes by a single astronomer, Scout correctly predicted the time and place of 2022 EB5’s encounter with Earth’s atmosphere. No one was around to see it, but a weather satellite recorded his last moment: a short-lived flame that is quickly consumed at night.
This isn’t Scout’s first successful prediction. In 2018, another small Earthbound asteroid was discovered 8.5 hours before the impact. Scout correctly determined its orbit, which proved of great importance to meteorite hunters who found two dozen surviving fragments in the lion-filled Central Kalahari Game Reserve in Botswana.
That won’t be possible for 2022 EB5.
“Unfortunately, it landed in the sea north of Iceland, so we won’t be able to recover the meteorites,” said Paul Chodas, the director of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory.
dr. Chodas said we also shouldn’t worry that this asteroid was discovered just two hours before its arrival.
“Small asteroids collide with Earth quite often, more than once a year for this size,” he said. And their size means that their impact is mostly without consequences. “Don’t worry about the little things,” said Dr. Chodas.
That Scout continues to prove his worth is welcome. But it won’t be much comfort if this program, or NASA’s other near-Earth object surveillance systems, identifies a much larger asteroid on our way, because Earth currently has no ways to protect itself.
The world is working hard to change that. Scientists are studying how nuclear weapons can divert or destroy threatening space rocks. And later this year, the Double Asteroid Redirection Test, a NASA space mission, will crash into an asteroid in an attempt to alter its orbit around the sun — a dry run for the day when we have to knock an asteroid out of the way of Earth. for real.
But such efforts will mean nothing if we remain unaware of the locations of potentially dangerous asteroids. And in that regard, there are still far too many known unknowns.
Although scientists suspect that most near-Earth asteroids large enough to cause global devastation have been identified, a handful may still be hiding behind the sun.
More worrisome are near-Earth asteroids about 460 feet in diameter, numbering in the tens of thousands. They could create urban destruction explosions “larger than any nuclear test ever conducted,” it said. Megan Bruck Syal, a planetary defense researcher at Lawrence Livermore National Laboratory. And astronomers estimate that they’ve currently found about half of them.
Even an asteroid just 60 feet across hitting Earth is “still having a really bad day,” said Dr. Bruck Syal. One such rock exploded over Siberia in 1908, flattening 800 square miles of forest. “That’s still 1,000 times more energy than the Hiroshima explosion.” And perhaps only 9 percent of near-Earth objects have been seen in this size range.
Fortunately, in the coming years, two new telescopes are likely to help with this task: the giant optical Vera C. Rubin Observatory in Chile and the space-based infrared Near-Earth Object Surveyor observatory. Both are sensitive enough to potentially find as many as 90 percent of those 460-foot-or-larger city killers. “As good as our capabilities are right now, we need these next-generation surveys,” said Dr. Chodas.
The hope is that time will be on our side. The chance that a city-destroying asteroid will hit Earth is about 1 percent per century — low, but not comfortably low.
“We just don’t know when the next impact will happen,” said Dr. Chodas. Will our planetary defense system be fully operational before that dark day arrives?
