How to protect the Earth from a rubble pile

Scientists are thinking about how to protect our planet from “rubble pile” asteroids. They are not bonded bodies that are held together only by gravity. The traditional way of deflecting space rocks may not produce a predictable result with them. 

The Bennu asteroid is a “rubble pile” type object. Source: NASA/Goddard/University of Arizona

“Rubble pile”

Scientists from different countries have recently published a lot of materials on what to do if our planet is threatened by the “rubble pile” asteroid. The traditional view of the problem of space rocks is that it is necessary to use kinetic impact to deflect them from a dangerous course. 

The DART experiment conducted last year, during which the striker hit the Dimorphos asteroid, showed the high effectiveness of this method. Even a small projectile hitting near the center of mass of a celestial body can significantly change its trajectory.

However, the same experiment showed that such a scenario could lead to the formation of a large amount of debris. This is especially dangerous in the case of the “rubble pile” bodies. They consist of a huge number of small pebbles that are held together solely by gravity.

The recently explored asteroids Ryugu and Bennu, the material from which was returned to Earth, belong to this type. And we do not know what is actually hiding under their surface, or how many such “rubble piles” are spinning near the Earth.

Problem of splitting

It is expected that the Vera Rubin telescope will be put into operation in the coming years. It will provide a way to track most of the dangerous asteroids around the Earth. However, this will not solve the problem of removing the “rubble piles” from it.

The fact is that a kinetic impact is highly likely to destroy such an object. And this is only good in Hollywood movies. In fact, the trajectory of the debris will be extremely difficult to determine, and they may remain large enough to cause trouble on Earth.

Therefore, scientists suggest other ways to prevent a catastrophe. One of them is the use of an ion-powered probe. The latter is capable of creating traction for months. Therefore, if you land the spacecraft on the surface of the “rubble pile” and give it constant acceleration, it will simply turn away from a dangerous course.

Another way is to use a gravity tractor. If the asteroid is relatively small, then a massive spacecraft nearby will simply create enough gravity to deflect it away from Earth. 

According to

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