Image shows exceptionally bright meteor that exploded over the Bering Sea on Dec. 18, 2018. The shadow of the meteor’s trail through Earth’s atmosphere can be seen, imaged by an instrument on NASA’s Terra spacecraft.
Credit: NASA/GSFC/LaRC/JPL-Caltech, MISR Team

A December 2018 fireball that zipped through the Earth’s atmosphere exploded about 16 miles (26 kilometers) high above the Bering Sea, unleashing an estimated 173 kilotons of energy. That’s a significant happening.

This incoming object was captured by a NASA satellite. Two NASA instruments aboard the multi-national Terra scientific research satellite spotted the fireball fly-in a few minutes after the event.

Cloud top trail

Images show the shadow of the meteor’s trail through Earth’s atmosphere, cast on the cloud tops and elongated by the low sun angle to the northwest. The orange-tinted cloud that the fireball left behind stems from super-heating the air as the meteor passed through.

According to NASA experts, the December 18 fireball was the most powerful meteor to be observed since 2013; however, given its altitude and the remote area over which it occurred, the object posed no threat to anyone on the ground.

Wake-up call: The 2013 incoming space rock over Chelyabinsk, Russia.
Credit: Alex Alishevskikh

City destruction

“Although the fireball was the second largest impact on Earth recorded in the last century, it still was too small to cause any significant damage, fortunately,” said Andrew Cheng of the Applied Physics Laboratory (APL) in Laurel, Maryland.

The Chelyabinsk meteor in 2013 that detonated over Russia was not much larger (about 20 meters) but damaged thousands of buildings and injured over 1,000 people.

“But an impactor only 100 meters across, if an asteroid that large were to hit a populated area, would be a disaster. Such an impact could destroy an entire city and its surrounding area,” Cheng told Inside Outer Space.

Artist concept of NASA’s Double Asteroid Redirection Test (DART) spacecraft. DART, which is moving to preliminary design phase, would be NASA’s first mission to demonstrate an asteroid deflection technique for planetary defense.
Credits: NASA/JHUAPL

Kinetic impact

Cheng is working on the Double Asteroid Redirection Test (DART), and offers some planetary defense counsel.

“So these fireball events are wake-up calls, and NASA has responded. NASA has approved its first planetary defense mission, which is DART. This mission will demonstrate the kinetic impact technique for deflecting an asteroid, by hitting it with a spacecraft to change its orbit,” Cheng explains.

DART will perform the kinetic impact demonstration at the 525-feet (160-meters) moon of the binary asteroid Didymos in late September-early October, 2022.

NASA is imminently going to announce the launch vehicle selection for DART.

For more information on this event, go to my new Scientific American story at:

Huge Meteor Explosion a Wake-Up Call for Planetary Defense – Detonating over the Bering Sea

https://www.scientificamerican.com/article/huge-meteor-explosion-a-wake-up-call-for-planetary-defense/

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