How an asteroid could end the world: Devastating effects and 5 preventive measures

In this modern era, there are tens, if not hundreds of things which are capable of wiping out the entire human race from the face of the Earth in no time. Global warming, World War 3, you name it. Potentially the most lethal of these all are the pieces of rocks in space. I’m talking about asteroids. In his last book, Stephen Hawking said that asteroids could potentially be the most dangerous threat to humanity’s existence. But if one were to hit Earth tomorrow, would we be prepared to defend ourselves?

Origin

The Sun was formed about 5 billion years ago. Not much later, pieces of rock and dust began coming together and forming what are known as ‘protoplanets’, which are the building blocks of planets. Hundreds of thousands of these protoplanets collided with each other, and formed planets. But there were still millions of these space rocks which did not form a planet. These collided with each other and formed smaller rocks, which we know as asteroids.

Asteroids are of various sizes. Thousands of small ones, less than 1 metre in diameter enter the Earth’s atmosphere every single day. Slightly bigger ones, the size of cars, enter the atmosphere once every year on an average. But these are not the asteroids to be scared of. The ones more than 1 km in size are the ones we should be worried about.

Asteroids which are within close proximity of the Earth are called Near Earth Objects, or NEOs. Today, we know about around 90% of the NEOs out there. Most are small in size, but few are several hundred metres across. NEOs even few centimeters across (called micrometeoroids) pose a great threat to the ISS, due to the large amount of momentum they possess.

Misconceptions

Before moving on to asteroid detection, I’d like to clear up a common misconception among people regarding them. There is actually a significant difference between a meteor, meteoroid and a meteorite, which are all different types of asteroids.

1. A meteoroid is a piece of rock and dust orbiting the Sun.
2. A meteor enters the Earth’s atmosphere, but burns up before reaching the surface.
3. A meteorite enters the Earth’s atmosphere, and reaches the ground safely.

Detection

To detect asteroids, thousands of pictures of the night sky are taken spread over several days. What scientists look for is a moving dot in the pictures. If the body is unidentified, it is examined and its trajectory is determined. If it is an asteroid, it is reported to the Planetary Defense Coordination Office, a body in charge of planetary defense planning.

Detecting them is not a piece of cake. They reflect only about 15% of light that falls on them, making them extremely hard to observe.

Effects of an asteroid impact

Various asteroids have different effects, depending on their size. Smaller ones cause less damage, but produce a sonic boom and small crater upon impact. However, when larger ones (>10 km) hit, they cause catastrophic damage. This is exactly what happened 66 million years ago, when the Chicxulub asteroid hit the Earth and caused the extinction of dinosaurs.

It caused earthquakes of more than 10 magnitude, tsunamis the size of skyscrapers. It formed a crater 180 km wide. Volcanic eruptions occurred all over the world. Land broke apart. But what was about to come was even worse. The dust and ash from volcanoes covered the Earth’s surface for several years, causing an Ice Age. All fauna perished, causing the death of the dinosaurs that remained. If this were to happen today, all human civilization would be destroyed. But is there anything we can do to prevent such cataclysm?

Prevention

There are, however, a few ways which we can adopt to prevent impact by deflecting the asteroid.

1. Nukes: Nukes are probably our best shot at defending ourselves from a big asteroid. Nukes can be sent into space and can be exploded near it, in order to change its course just enough to miss Earth. However, this has never been tested, as the Outer Space Treaty prohibits the presence of nuclear weapons in space. The asteroid can come together again due to its gravity, making our effort futile.
2. Retro rockets: We can send rockets on the surface of the asteroid and turn them on, so they move it from its course, just enough to miss Earth. However, one factor that needs to be considered is that the asteroid also rotates about itself, just like the Earth does. Thus, all energy is distributed in all directions, making no change in its overall course.
3. Impactor: Hitting the asteroid by ramming a space probe into the asteroid to change course is a reliable option, as it has been tested by NASA’s DART mission. However, this can’t be used on those >1 km wide.
4. Lasers: Using lasers is not an option that can be used with today’s technology, as unimaginably powerful lasers would be required. Even if we could get the laser into space, building such a powerful laser is still out of our reach.
5. Mining: Another approach that may work is mining the asteroid. This way, these dangerous planet-killing pieces of rock, can in-fact, be used to our advantage. A spacecraft can be sent into space to retrieve the resources. However, the amount of profit we will gain from this (in billions) is significantly less than the cost of the project (in trillions). Refer to our article about asteroid mining for more information.

If all else fails, evacuation is the best strategy to adopt to reduce loss of life.

Previous Encounters

1. Chelyabinsk: In February 2013, an asteroid 20 metres across exploded above the Earth’s surface in Chelyabinsk, Russia, causing a shock wave, which broke windows and caused 1000-1500 injuries, but no deaths. After this, the Planetary Defense Coordination Office was established.
2. Tunguska event: In 1908, an asteroid exploded over Tunguska in Siberia. When scientists arrived, they found hundreds of fallen trees, but no meteorite. Later, it was revealed that the meteorite had exploded 5-10 km above Earth, leaving no remnant.

It is often heard that an asteroid called Apophis has a 2.7% chance of hitting Earth in 2029. However, latest data has confirmed with certainty that it will pass within 32,000 km of Earth but will not hit us.

We often hear about news from NASA that a meteoroid will pass close to Earth and may hit it in a few days. In reality, the probability of the occurrence of such an event is negligible (less than 1%). With the current detection technology, there is a slim chance that we miss any potentially dangerous ones. So you have nothing to worry about.

Click here to learn about asteroids in detail.

Conclusion

Earth is hit by an extinction level asteroid once every 100 million years. We don’t have much time left. We must work on new technologies to deal with future impacts, because with current technology, we will not be able to deflect asteroids greater than few hundred metres in diameter. We need to move to other planets, to ensure the continuity of the human race. We cannot put all our eggs in one basket. (Click here to read our article about colonisation for more info). When do you think we will invent the technology to deflect lethal asteroids? Let us know in the comments below.

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