On February 15, 2013, Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory (JPL) in California, was preparing for a NASA TV segment about the flyby. of a near-Earth asteroid. , 2012 DA14, which should come within 17,200 miles (27,680 kilometers) of Earth.
During this prep work, Chodas received a YouTube clip of a large fireball exploding in the skies over Chelyabinsk, a city in the Ural region of Russia.
Chodas was skeptical at first. “Initially, there was a lot of confusion. People were like, ‘Oh, we got our prediction wrong.’ And I assured them no, we knew exactly where the asteroid was and it was passing through the GEO (geostationary) belt. But this Chelyabinsk asteroid was just a totally independent event coming from a different direction,” Chodas told Space.com.
As it turned out, videos sent to Chodas showed an 18-meter near-Earth asteroid exploding through the atmosphere after surprising scientists by coming from the direction of the sun, a blind spot for telescopes and other sensors on the ground. . O resulting explosion caused millions of dollars in damage in Chelyabinsk and injured thousands of residents across an area hundreds of kilometers wide. Most injuries were caused by broken glass, although hundreds of Chelyabinsk residents suffered eye damage from the explosion that briefly lit the skies brighter than the sun. A few dozen reported burns caused by the intense ultraviolet radiation caused by the explosion.
Related: See photos of the Chelyabinsk meteor explosion
Ten years later, the Chelyabinsk meteor explosion and the damage it caused highlights the need for asteroid-tracking telescopes like NASA’s. NEO Surveyorplanetary defense missions such as Double Asteroid Redirection Testand research organizations such as the CNEOS (opens in new tab). While there are currently no known asteroids that are on a collision course with Earth, unexpected objects routinely collide with the atmosphere. with just a few hours notice. And in the case of Chelyabinsk, sometimes asteroids can come undetected through blind spots in our detection capabilities.
However, there’s no need to lose sleep over the threat of asteroids. “There are no known large asteroids that have any significant chance of hitting Earth,” Chodas assured us.
After the Chelyabinsk meteor exploded, infrasound sensors designed to detect nuclear detonations helped scientists determine that the explosion was indeed incredibly powerful. “This was a big event, the biggest we’ve ever measured,” Chodas said. “On our fireball page, which measures all the highest impact events, this was by far the biggest. So it was an amazing experience, I have to say.”
Initially, the explosion was estimated at between 300 and 400 kilotons, but more recent estimates put the size at 500 kilotons. By comparison, the Fat Man nuclear warhead dropped on the Japanese city of Nagasaki during World War II had a yield of 21 kilotons.
Chodas added that it is fortunate that the event was initially recognized for what it was and not interpreted as some sort of military event. Chelyabinsk Oblast, the administrative region of which the city of Chelyabinsk is the seat, is home to the Pan-Russian Institute of Technical Physics (opens in new tab)one of two facilities in Russia that manufacture nuclear weapons.
“But of course, it was much bigger than you would expect from any kind of attack on the city. So I think I’m happy that that was the initial reaction and that the correct initial reaction was that it was a natural event,” Chodas said.
See more information: Meteor explosion in Russia is the biggest in 100 years
While Chelyabinsk was indeed a natural event, the size of the meteor makes it stand out among the many smaller impacts that routinely occur in the atmosphere. While smaller meteor impacts and fireballs are somewhat common, impacts like Chelyabinsk or the tunguska event 100 years earlier are much rarer due to the fact that larger objects are exponentially less common throughout the solar system than smaller ones.
“It all depends on what size you’re talking about,” Chodas said. “I mean, small objects hit us every day. You can go out and see meteor showers, and these are small pebble-sized objects, which are extremely numerous. That’s why these impacts are common. And that’s one thing. hard to understand. As you go up to larger and larger sizes, the impacts become less and less frequent. And that’s an exponential drop, by the way. So it’s important to understand that.”
Chodas added that despite frequent headlines sensationalizing any “close” asteroid flyby, distances that fall under the definition of near-Earth can be misleading. For example, an asteroid called 2005 YY128 will fly by Earth on February 15 at a distance of 2.8 million miles (4.5 million km), an encounter that generated quite a stir in the media but poses no danger to us.
“That’s just astronomically close,” Chodas said. “So the important thing, I hope, for the public to understand is that a lot of these close approaches are quite far away. And we know the trajectories very accurately.” Chodas added that 2005 YY128 has been tracked by CNEOS for 17 years and its orbit has been accurately predicted to within 100 miles (160 km). “So there’s no chance that this poses a danger,” Chodas added.
See more information: Meteor explosion in Russia was the largest detected by the nuclear monitoring system
One reason for these constant headlines is the fact that NASA and other space agencies are detecting asteroids and other space rocks at a much more frequent rate, thanks to various initiatives the agency has undertaken in recent years.
The “asteroid discovery rate has increased dramatically,” Chodas said.
Projects like the next one from NASA NEO Surveyor The asteroid hunter telescope will help identify and track these objects with greater sensitivity than before. Using infrared sensors, the space telescope will be able to look for multiple near-Earth objects at the same time. “I like to make the analogy that looking for asteroids is like fishing in the ocean,” said Chodas. “And really, if you want to catch more fish, you need a bigger net.”
NEO’s current detection and tracking capabilities are not sensitive enough to detect distant objects, but NEO Surveyor should help remedy this, allowing NASA to detect and catalog asteroids at much greater distances than current technologies allow. “And that’s a really important goal, because our biggest and strongest defense against an asteroid impact is finding the asteroid early. And to do that, you need a state-of-the-art capability,” explained Chodas.
NEO Surveyor is scheduled to launch in June 2028. For more information about near-Earth objects and efforts to study and catalog them, visit the CNEOS website (opens in new tab).
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