Recent asteroid crash serves as a test case for a system that could save Earth; understand

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Movies that imagine an asteroid or comet colliding catastrophically with Earth always include a pivotal scene: a lone astronomer sees the errant space rock hurtling toward us at high speed, creating panic and creating a growing mood of existential dread as the researcher broadcasts the news to the world.

On March 11 of this year, life began to imitate art. That night, at the Konkoly Observatory’s Mount Piszkéstető station near Budapest, Krisztián Sárneczky was looking at the stars. Dissatisfied with the 63 asteroids approaching Earth that he had discovered over the course of his professional life, Sárneczky wanted to discover the 64th. And it did.

At first glance, the object he saw looked normal. “It wasn’t moving very fast,” Sárneczky said. “It wasn’t brighter than usual.” Half an hour later, however, he noticed that “his movement was faster. That’s when I realized he was rapidly approaching us.”

It might sound like the start of a melodramatic disaster movie, but the asteroid measured less than two meters long — meaning it was insignificant and harmless. And Sárneczky vibrated.

“I’ve dreamed many times of making a discovery like this, but it seemed impossible,” he explained.

Not only had he seen a new asteroid, he had spotted it just before it hit planet Earth. It was only the fifth time such a discovery had been made.

The object, which would later be named 2022 EB5, may have been harmless, but it turned out to be a good test of tools built by NASA to defend our planet and its inhabitants from a collision with a more dangerous space rock.

One such system, Scout, is software that uses observations made by astronomers of objects moving close to Earth and calculates roughly where and when they might impact our planet. In less than an hour after detecting the 2022 EB5, Sárneczky had shared his data, and it was being quickly analyzed by the Scout.

2022 EB5 was going to collide with Earth just two hours after it was discovered, but even then the software was able to calculate that it would enter the atmosphere off the east coast of Greenland. And that’s exactly what he did at 5:23 a.m. local time on March 11, exploding in midair.

“It was a wonderful hour and a half of my life,” Sárneczky said.

EB5 was small, but an asteroid doesn’t have to be vastly larger than it is to be a hazard. For example, the 16.7-meter rock that exploded in 2013 over the Russian city of Chelyabinsk set off an explosion equivalent to 470 kilotons of TNT, shattering thousands of windows and injuring 1,200 people.

The fact that the Scout software is able to accurately map the trajectory of a much smaller asteroid is reassuring to some extent. If the asteroid in question is detected long enough, a city facing a space rock like Chelyabinsk could at least receive some early warning of the danger.

It usually takes a few days of observations to confirm the existence and identity of a new asteroid. But if this object is determined to be a small but dangerous space rock that is about to crash into Earth, the decision to wait for additional data could have disastrous consequences.

“That’s why we developed the Scout,” said Davide Farnocchia, an engineer at the Jet Propulsion Laboratory that developed the program, which launched in 2017.

Scout constantly examines data posted by the Minor Planet Center, a data repository in Cambridge, Massachusetts, which takes note of the discoveries and positions of small space objects. The software then “seeks to calculate whether something is coming towards Earth,” Farnocchia said.

The fact that Sárneczky was the first to spot 2022 EB5 was a matter of skill as well as luck: Sárneczky is an experienced asteroid hunter who, by a fluke, was in the right place in the world to be able to see the object on its path. towards Earth. And his efficiency allowed the Scout to spring into action.

Within an hour of making his observations, Sárneczky processed his images, confirmed the object’s coordinates, and sent it all to the Minor Planet Center.

Using 14 observations taken in 40 minutes by a single astronomer, Scout correctly predicted the time and location of 2022 EB5’s encounter with Earth’s atmosphere. No one was present to see it, but a weather satellite recorded its final moment: an ephemeral flame that quickly disappeared into the night.

It’s not the first successful prediction made by the Scout. In 2018, another tiny asteroid heading for Earth was discovered, 8.5 hours before impact. The Scout mapped its trajectory correctly, which was of great use to meteorite hunters who found two dozen remaining fragments in Botswana’s lion-filled Central Kalahari Game Reserve.

This will not be possible for the 2022 EB5.

“Unfortunately it 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.

The fact that the Scout continues to prove its worth is welcome. But it won’t be of much help if this program or other NASA systems for monitoring near-Earth objects spot a much larger asteroid heading our way, because Earth currently has no means of protecting itself.

There is a global effort being made to change this situation. Scientists are studying how nuclear weapons could deflect or annihilate dangerous space rocks.

And later this year the Dual Asteroid Redirection Test, a NASA space mission, will collide with an asteroid in an attempt to alter its orbit. It will be a practical rehearsal for the day when we need to deflect an asteroid from Earth for real.

But these efforts will be futile if we don’t know the exact location of potentially dangerous asteroids. And there are still too many unknowns in this regard.

While scientists suspect that most near-Earth asteroids that are large enough to cause global devastation have already been identified, it is still possible that some are hiding behind the Sun.

Of more concern are near-Earth asteroids with a diameter of approximately 140 meters, of which there are tens of thousands. They are capable of creating explosions that can flatten cities, “larger than any nuclear test ever conducted,” said Megan Bruck Syal, a planetary defense researcher at Lawrence Livermore National Laboratory. And astronomers estimate that so far they’ve discovered about half of them.

Even an asteroid with a diameter of just 50 meters that collided with Earth would be “terrible”, said Bruck Syal.

A rock of this type exploded over Siberia in 1908, flattening 2,000 kmtwo of forest. “It’s a thousand times more energy than the Hiroshima explosion,” said the researcher. And it’s possible that only 9% of objects roughly this size near Earth have ever been detected.

Fortunately, in the next few years two new telescopes should begin to help with this task: the gigantic Vera C. Rubin Optical Observatory in Chile and the Near-Earth Object Surveyor infrared observatory, located in space.

Both are sensitive enough to potentially locate up to 90% of those 140-meter and larger asteroids capable of flattening cities. “As good as our capabilities are right now, we really need these next-generation instruments,” Chodas said.

Translation by Clara Allain

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