Look up: How Earth Protects itself from asteroids

It is very unlikely that an asteroid that can extract an entire city will be able to hit Earth within eight years. But even if this asteroid rushes us down our path, experts say, humanity can now protect us from such threats.

NASA said Tuesday that the likelihood of a recently discovered asteroid hitting Earth on December 22, 2032 has risen to 3.1%.

“Don’t panic,” Richard Moisle, director of Planetary Defense, the European Space Agency, told AFP.

As astronomers collect more data, the odds of direct hits are widely expected to be superior upward before rapidly falling to zero.

But even in events where odds are unlikely to continue to rise to 100%, “we are not defenseless,” Moissl emphasized.

Here are some of the ways in which humanity can deflect or destroy an asteroid known as the 2024 YR4.

Destroy the spaceship

Only one planetary defense strategy has been tested on a real asteroid.

In 2022, NASA’s Double Astree Redirect Test (DART) intentionally crushed the spacecraft into a 160-meter wide Dimorphos asteroid, successfully changing its orbit around the larger space rock.

The advantage of this plan is that it can attack asteroids in 2024 with multiple spacecraft. It’s about observing how Bruce Betts, the chief scientist of a nonprofit planetary society, changed his orbit.

The asteroid discovered in December is estimated to be 40-90 meters wide.

“You have to be careful not to overdo it,” warned Moisle.

If the spacecraft partially destroys the asteroid, it could send a “flying” that is still heading towards Earth, he said.

If this type of accident changes the site of the final shocking site on the planet (for example, “from Paris to Moscow,” it is likely to cause major problems in your hometown, Betts added.

Tractor, ion beam, paint

Another idea called a gravity tractor involves a large spacecraft flying near an asteroid, and uses gravity pulls to pull it from Earth without touching it.

Another contactless scheme is armed with thrusters that allow spacecraft near the asteroid to be exerted “a constant flow of ions” to remove the asteroid, Moissl said.

Scientists also thought of spray painting one side of the asteroid’s white side, increasing its reflectivity and slowly changing its orbit.

These subtle strategies need to reach the asteroid faster than some more serious options.

Nuclear options

Alternatively, you can blow it up with a nuclear bomb.

Rather than excavating nuclear weapons deep inside the asteroid, as depicted in the 1998 sci-fi action film Armageddon, this would probably involve detonating nearby bombs.

Last year, US researchers testing this theory of lab marble-sized mock asteroids discovered that x-rays from nuclear blasts evaporate their surfaces and shoot them down in the opposite direction.

Putting aside the ethical, political and legal issues of sending nuclear weapons into space, this is considered the final ditch plan for asteroids across the entire kilometers, like a dinosaur-kilometer-slaying.

Again, there is a risk that nuclear explosions could still send unpredictable masses that surge towards Earth.

Laser

While not too dangerous, along a similar line, another idea is to fire a laser beam from the spacecraft, evaporate and push the asteroid’s sides away.

Lab experiments suggest that the plan is feasible, but it is not one of the “top techniques” seen, Betts said.

If everything else fails

If necessary, deflecting this asteroid is “feasible, but depends on the speed at which it moves as a planet,” Moisle said.

While experts and space agencies make recommendations, ultimately decisions about how to tackle asteroids will be made by world leaders.

If everything else fails, we have a good idea about the asteroid strike zone. This isn’t a “planet killer” and could at best threaten the city, Moisle said.

This means that preparing for potentially evacuation impacts will be the final line of defense if the area is large inhabitant.

“Seven and a half years is a long time to prepare,” Moissl said, re-emphasing that there is about a 97% chance that asteroids will miss Earth.

©2025 AFP