Asteroids still pose a threat to Earth

They are the remnants of pieces from the composition of our solar system. Humanity might not have existed without it – but it is also threatened by them: asteroids may have brought the basis of all life to Earth – but the impact today could have disastrous consequences. However, humanity is not defenseless.

“This is the only natural disaster we can account for in advance,” says Detlev Koschny, an asteroid expert at the European Space Agency (ESA) in Noordwijk, the Netherlands, on World Asteroid Day on June 30. Bombing asteroids like in blockbuster movies is no longer just a fantasy. However, for some of the pieces, there are huge gaps of note.

According to the US space agency NASA, there are more than one million known asteroids in our solar system, of which more than 20,000 so-called Near Earth Objects (NEOs) transit our orbit around the Earth during its orbit. Two famous events show what such slashing can do: On June 30, 1908, the shock wave of an asteroid explosion likely swept millions of trees in Tunguska in Siberia in an area roughly the size of Saarland.

In light of this event, the United Nations later declared June 30 International Asteroid Day. In February 2013, an asteroid 20 meters in size and traveling 66,000 kilometers per hour exploded over the city of Chelyabinsk. About 1,500 people were injured in the blast, most of them from window shards. Thousands of buildings were damaged.

But millions of years ago, such bits of rock and metal from space could have made life on Earth possible in the first place. Koschny explains that models said there would be much less water on Earth if there was no external supply. It does not come from comets. “The type of water is not suitable. What remains are asteroids.” It is at least a common theory that they brought water to Earth.

“The next question is: Is it possible that they have already brought some organic parts to Earth?” expert says. Man as an alien, so to speak? Not right. Some of the organic matter may have come ‘from outside’, but the further evolution towards life then occurred on Earth.

Twelve kilometer block trail in Mexico

Certainly, the development of life on our planet was strongly influenced by a subsequent event: the impact of a twelve-kilometre-wide segment in Mexico 60 million years ago is considered to be the cause of the extinction of the dinosaurs. This was the only reason the mammals were able to establish their existence after that, says Koschny.

And today? Glowing objects constantly appear in the night sky – dust and small pieces of rock from space burning in the atmosphere. “The total mass that reaches the Earth is estimated to be about 100 tons per day,” Koschny says. Large pieces are still a hazard. Warning protocols are in effect from a size of about 20 meters, says ESA’s Senior Asteroid Defense Coordinator Richard Moisel, whose team operates in Frascati near Rome.

The European Space Agency and NASA want to research asteroid bombing as a potential defense option. NASA’s Dart probe, which has already launched, is set to collide with the smaller portion of a double asteroid in September and shift its orbit slightly around the larger asteroid. The European Space Agency’s Hera mission is scheduled to begin in 2024 and take measurements there.

Nuclear weapons as protection against asteroids

“This so-called kinetic effect is the most promising technology because we already have it,” Moisel says. The action depends on the pre-warning time and the size of the object. “The last option is to use nuclear weapons, because that’s the most available amount of energy you can deposit in an object in the shortest possible time.”

However, experts still see loopholes in asteroid monitoring. According to Koschny and Moissl, observations are still made almost exclusively from Earth. “In the future we will need space telescopes to have a better early warning system,” Moisel says. “We have to close the monitoring gaps.”

Small cutting risk

Really big blocks aren’t the problem. “The things we all think we know,” Koschny says. “What is the current threat in the 20-40 meter range.” With an object 40 meters high above a larger city, you have to evacuate – and in this size range, you only know a small percentage of the potential candidates.

But people should not feel fear and anxiety right now. “I can rule out a threat to civilization at the moment,” Koschny says. And Moissl doesn’t see anything serious coming down to Earth at the moment either. “I can already sleep well right now.”

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