(ORDO NEWS) — A huge amount of stones and other materials fly around the solar system in the form of asteroids and comets.
If one of them came close to us, could we successfully prevent the asteroid from colliding with the Earth?
Well, maybe. But there seems to be one type of asteroid that is particularly difficult to destroy.
Asteroids are chunks of rocky debris in space, remnants of a more violent past in our solar system.
Studying them could reveal their physical properties, clues to the ancient history of the solar system, and the threats these space rocks could pose if they collided with Earth.
In our new study, published today in the Proceedings of the National Academy of Sciences, we found that debris asteroids are an extremely stable type of asteroid and are difficult to destroy in a collision.
Two main types of asteroids
Asteroids, mostly concentrated in the asteroid belt, can be divided into two main types.
Monoliths, made up of a single piece of rock, are what people usually have in mind when they think of asteroids.
Monolithic Asteroids o It has been predicted that the lifetime of a kilometer diameter in the asteroid belt will be only a few hundred million years. This is quite a bit, given the age of our solar system.
Another type is asteroids from a pile of rubble. They consist entirely of many fragments ejected during the complete or partial destruction of pre-existing monolithic asteroids.
However, we don’t really know the strength and therefore the potential lifespan of a pile of rubble. asteroids.
Vile and numerous piles of debris
In September 2022, the NASA DART (Double Asteroid Redirection Test) mission successfully collided with the asteroid Dimorphos.
The purpose of this mission was to see if we could deflect an asteroid by colliding with it with a small spacecraft, and it was a resounding success.
Like other recent asteroid missions conducted by the Japan Aerospace Exploration Agency (JAXA).
To visit the asteroids Itokawa and Ryugu, and NASA to the asteroid Bennu, close-up images have shown that Dimorphos is another asteroid from a pile of rubble.
These missions showed us that rubble asteroids have a low density because they are porous. Plus they are in abundance.
In fact, there are a lot of them, and since they are fragments of monolithic asteroids, they are relatively small and therefore difficult to detect from Earth.
Therefore, such asteroids pose a serious threat to the Earth, and we really need to understand them better.
Asteroid Dust Lessons
In 2010, the JAXA-designed Hayabusa spacecraft returned from the 535-meter peanut-shaped Itokawa asteroid.
The probe brought with it over a thousand rock particles, each smaller than a grain of sand. These were the first ever samples delivered from an asteroid!
As it turned out later, images taken by the Hayabusa spacecraft while it was still orbiting Itokawa demonstrated for the first time the existence of asteroids consisting of debris. .
Preliminary results from the JAXA team, which analyzed the returned samples, showed that Itokawa formed after the complete destruction of a parent asteroid that was at least 20 kilometers across.
In our new study, we analyzed several dust particles returned from the Itokawa asteroid using two methods: the first one fires an electron beam into the particle and detects the electrons that scatter back. It tells us whether the rock has been hit by a meteorite.
The second method is called argon-argon dating and uses a laser beam to measure the amount of radioactive decay that has taken place in a crystal. This gives us the age of such a meteorite impact.
Giant space pillows that last forever
Our results show that the huge impact that shattered Itokawa’s parent asteroid and formed Itokawa happened more than 4.2 years ago. a billion years ago, which is almost as old as the solar system itself.
This result was completely unexpected. This also means that Itokawa lived almost an order of magnitude longer than its monolithic counterparts.
Such a surprisingly long survival time of the asteroid is due to its shock-absorbing nature. Due to the fact that Itokawa is a pile of rubble, the porosity is about 40 percent.
In other words, almost half of it is hollow, so the constant collisions will simply destroy the gaps between the stones, and not destroy them. the rocks themselves.
So, Itokawa is like a giant space pillow.
This result indicates that there are far more asteroids from the boulder pile in the asteroid belt than we once thought. Once they form, they are very difficult to destroy.
This information is critical to preventing any potential asteroid impact with Earth.
While the DART mission successfully nudged the orbit of the asteroid it targeted, there is very little transfer of kinetic energy between the small spacecraft and the debris asteroid.
This means that they are inherently resistant to breakage in the event of an impact.
Therefore, if the Earth is threatened by an imminent and unforeseen threat in the form of an approaching asteroid, we need a more aggressive approach.
For example, we may need to use the shock wave of a nuclear explosion in space, since large explosions can transfer much more kinetic energy to an asteroid from a naturally cushioned rubble pile and thus push it away.
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