Dust particles from an asteroid could save Earth from doomsday

Destroying an Earth-killing asteroid is not always possible, here's what we can do instead. 
Rupendra Brahambhatt
Asteroid Itokawa.
Asteroid Itokawa.

© Kevin M. Gill 

Do you know what size asteroid would be enough to end all life on Earth? According to the experts at NASA, a space rock only 96 km wide can do the job. 

So, to keep our planet safe, it is critical to investigate various types of space rocks and devise counter-strategies in the event any of these are on a collision course with Earth. However, to study space rocks or asteroids, scientists need samples. 

In 2005, for the first time, a Japanese space capsule Hayabusa brought the dust particles of an asteroid named Itokawa to Earth. Researchers at Curtin University in Australia have been investigating three dust particles taken from Itokawa. 

In their recently published study, the researchers reveal exciting information that could help us save our planet in case Earth faces a threat from an asteroid like Itokawa.   

Can we stop an asteroid from hitting Earth?

Scientists at NASA suggest that Itokawa originated from a larger space rock about 4.2 billion years ago. It is located at a distance of 2 million km (1.24 million miles) from Earth and is about 500 meters in diameter, i.e., almost as big as the Sydney Harbor Bridge in size.

Plus, Itokawa is no ordinary single-piece space rock. It's a special rubble pile asteroid made of numerous rocks and boulders loosely held together because of their collective gravity. Now think about it, if a space rock has managed to survive over 4 billion years in outer space, which is itself an extremely harsh environment. 

Do you think it would be easy to destroy such an asteroid if it's on a path to hit Earth? 

While responding to this question, lead author and professor at Curtin, Fred Jourdan, said in a press release, "The huge impact that destroyed Itokawa's monolithic parent asteroid and formed Itokawa happened at least 4.2 billion years ago. Such an astonishingly long survival time for an asteroid the size of Itokawa is attributed to the shock-absorbent nature of rubble pile material. In short, we found that Itokawa is like a giant space cushion, and very hard to destroy."

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Insights from the analysis of Itokawa dust 

Dust particles from an asteroid could save Earth from doomsday
Itokawa asteroid dust particle (in the pit).

Imagine an asteroid like Itokawa is approaching Earth, and there is no way to destroy it before it hits our planet. How could we save ourselves in such a case? In order to find the answer to this question, the authors examined the asteroid samples using the electron backscattered diffraction (EBSD) method and argon-argon dating.

In the first method, an electron microscope is used to study the crystal structure of a material. It is possible Itokawa has been hit by many space rocks in the past. However, if it has ever been affected structurally due to such collision with meteors or rock, EBSD will detect it. 

Argon-argon dating on the other side reveals the time that has passed since an asteroid's impact. The fact that Itokawa is basically of the same age as our solar system suggests that rubble pile asteroids are found in abundance in the asteroid belt. 

So, if an asteroid is going to hit Earth, it's more likely to be a rubble-pile asteroid. 

If you are scared to hear this, don't worry; the analysis from Curtin didn't only reveal scary details. The authors explained that if we are not in a position to destroy an asteroid like Itokawa, using the data from the research, we can push it away and force it to change its course.   

"The good news is that we can also use this information to our advantage - if an asteroid is detected too late for a kinetic push, we can then potentially use a more aggressive approach like using the shockwave of a close-by nuclear blast to push a rubble-pile asteroid off course without destroying it."

These findings are important because they highlight the right approach that could work against an asteroid such as Itokawa. Without such research works, in case of an asteroid threat, we may waste a lot of time juggling between different counter strategies.  

The study is published in the journal PNAS.