Asteroids are the super-sized space rocks capable of causing apocalyptic damage to life on Earth. US space agency NASA is alive to the danger deadly asteroids pose for the mankind’s future, and is even preparing plans to destroy space rocks on a trajectory towards our planet. However, incoming asteroids may in fact be harder to destroy than previously thought, according to a shocking new study.
A popular theme in films features a rogue asteroid barrelling towards Earth, only for it to be blown it up by heroic astronauts.
Asteroids are stronger than we used to think and require more energy to be completely shattered
But any asteroids on an apocalyptic approach will be harder to destroy than scientists previously believed.
This is the conclusion of a landmark new study by Johns Hopkins University, combining the latest analysis of rock fracture and a new computer modelling simulating asteroid collisions.
And the findings will not only affect the next generation of asteroid deflection strategies.
They study will aid understanding of the solar system’s formation and even help design asteroid mining efforts.
Charles El Mir, the study’s lead author, said: "We used to believe that the larger the object, the more easily it would break, because bigger objects are more likely to have flaws.
“Our findings, however, show that asteroids are stronger than we used to think and require more energy to be completely shattered.”
While researchers understand rocks at fist-sized scale, it has been difficult to translate this understanding to city-size “planet-killer” asteroids.
In the early 2000s, a research team created a seminal simulation of a one km-wide asteroid slamming into a 25km space rock at five km per second.
Their results suggested that the target asteroid would be completely destroyed by the impact.
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However, the new study saw the same scenario entered into a new computer model which accounts for the more detailed, smaller-scale processes that occur during an asteroid collision.
Previous models did not properly account for the limited speed of cracks in the asteroids.
Mr El Mir said: ”Our question was, how much energy does it take to actually destroy an asteroid and break it into pieces?.
“The simulation was separated into two phases: a short-timescale fragmentation phase and a long-timescale gravitational recollection phase.
The first phase considered the processes that begins immediately after an asteroid is hit - an action that occurs within fractions of a second.
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The second, long-timescale phase considers the effect of gravity on the pieces that fly off the asteroid's surface after the impact, with gravitational regathering occurring over the impact’s aftermath.
In the first phase, after the asteroid was hit, millions of cracks formed and rippled throughout the asteroid, parts of the asteroid flowed like sand, and a crater was created.
And the new model showed that the entire asteroid is not destroyed by the impact.
Instead, the impacted asteroid had a large damaged core that then exerted a strong gravitational pull on the fragments in the second phase of the simulation.
The research team found that the end result of the impact was not just a "rubble pile—a collection of weak fragments loosely held together by gravity.”
Instead, the impacted asteroid retained significant strength because it had not cracked completely, indicating that more energy would be needed to destroy asteroids.
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Meanwhile, the damaged fragments were now redistributed over the large core, providing guidance to those who might want to mine asteroids during future space ventures.
El Mir said: ”It may sound like science fiction but a great deal of research considers asteroid collisions.
“For example, if there's an asteroid coming at earth, are we better off breaking it into small pieces, or nudging it to go a different direction?
“And if the latter, how much force should we hit it with to move it away without causing it to break? These are actual questions under consideration.”
K.T. Ramesh, director of the Hopkins Extreme Materials Institute, added: “We are impacted fairly often by small asteroids, such as in the Chelyabinsk event a few years ago.
"It is only a matter of time before these questions go from being academic to defining our response to a major threat.
“We need to have a good idea of what we should do when that time comes—and scientific efforts like this one are critical to help us make those decisions."
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