Asteroids ‘still a danger’ – how humans could prevent their impact

Asteroids are stony leftovers from the formation of our solar system. They may have provided the foundations of all life on earth – but an impact today could have devastating consequences. However, humanity is not defenseless. “It’s the only natural disaster we can calculate in advance,” says Detlef Koschny, asteroid expert at the European space agency ESA in Noordwijk, the Netherlands, on International Asteroid Day. June 30.

An asteroid bombardment like in the blockbusters is no longer pure fiction. For some tracks, however, there are huge observation gaps.

Experts say asteroid impacts should be taken seriously – historical examples show strength

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 are so-called near-Earth objects (NEOs) that pass through our Earth orbit during their orbit. orbit. Two well-known events show what such chunks can do: On June 30, 1908, the pressure wave from an asteroid explosion – probably – swept through millions of trees at Tunguska in Siberia in an area almost the size of the Saar. In view of this event, the United Nations then proclaimed June 30 as International Asteroid Day.

In February 2013, an asteroid about 20 meters in size and moving at 66,000 kilometers per hour exploded above the city of Chelyabinsk. About 1,500 people were injured in the blast, mostly from shattered glass. Thousands of buildings were damaged.

Glowing objects are constantly visible in the night sky – dust and small pieces of space rock burning in the atmosphere. “The total mass that descends to earth is estimated at 100 tons per day,” says Koschny. Large chunks can still present a hazard. The warning protocols take effect from a height of about 20 meters, specifies the chief coordinator of defense against asteroids at ESA, Richard Moissl, whose team works in Frascati near Rome.

Fire as a possible defense option

ESA and NASA want to study asteroid bombing as a possible defense option. NASA’s “Dart” probe, which has already been launched, is due to touch the smaller piece of a twin asteroid in September and shift its orbit slightly around the larger one. The Esa “Hera” mission should start in 2024 and take measurements there.

“So-called kinetic impact is seen as the most promising technology because we already have it,” says Moissl. The procedure depends on the warning time and the size of the object. “The last option is to use nuclear weapons, as it is the greatest amount of energy available that can be deposited into an object in the shortest possible time.”

However, experts still see gaps in asteroid monitoring. According to Koschny and Moissl, observations are still almost exclusively made from Earth. “In the future, we will need space telescopes to have a better early warning system,” says Moissl. “We need to close the observation gaps.” Very large pieces are not the problem. “The objects we all think we know,” says Koschny. “What is an existing threat is the size range of 20 to 40 meters.” With an object 40 meters above a larger city, you would have to evacuate it – and in that size range you only know a few percent of possible candidates.

But people don’t have to be scared and anxious right now. “I can rule out a threat to civilization at this time,” Koschny says. And Moissl doesn’t see anything serious happening on earth at the moment either. “Actually, I can sleep just fine right now.”