Asteroids are Harder to Destroy than Previous Estimates

Researchers used a new computer modeling technique to simulate asteroids that helped them improve their understanding of rock fracture.  

According to a new study at the John Hopkins University, incoming asteroids are much stronger than scientists previously thought. This study will help scientists to come up with improved asteroid mining methods as they will be able to simulate asteroid impacts and deflection strategies. In addition to that, the latest findings, published in ‘Icarus’ on 15^th March, have challenged a long-lasting belief: the larger the object, the more easily it would break. Charles El Mir, the First Author of the paper and a Ph.D. graduate from the Department of Mechanical Engineering at the John Hopkins University, acknowledged that by saying,

“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.”

Past Experience

It has always been difficult for scientists to understand massive asteroids because most of the work they do is confined to a laboratory. Having said that, some efforts have been made (in the past) to figure out the results of a colossal asteroid collision. In the early 2000s, a group of researchers developed a computer model that had several inputs like temperature and mass. They simulated a collision where a kilometer-wide asteroid smashed head-on into a target asteroid, having a diameter of 25 kilometers. The impact velocity was set at 5 kilometers per second and it was observed that the target asteroid was destroyed.

The Speed of Cracks in the Asteroids

The researching team of El Mir incorporated more details and small-scale processes into their computer model (called the Tonge-Ramesh Model) in order to get improved results of an asteroid collision. They wanted to have a closer look at the speed of cracks in the asteroids so that they could determine the critical energy needed to break the massive structure into pieces. El Mir clarified their intentions in the following words:

“Our question was, how much energy does it take to actually destroy an asteroid and break it into pieces?”

The Simulation

The entire process of simulation was divided into two phases. The first phase was named as a short-timescale Fragmentation Phase and it covered all the rapid processes that begin instantly after an asteroid is hit. On the other hand, the second phase of the simulation is called the Gravitational Reaccumulation Phase and it continues to take place over a long-timescale. During the first phase of the simulation, it was observed that an asteroid impact creates millions of cracks in the impacted asteroid. This phase of the model studied the individual cracks and an overall pattern of their propagation throughout the target.

The second phase analyzes the effect of gravity on the broken parts of the impacted asteroid as gravitational accumulation continues to take place for several hours after impact. Contrary to previous beliefs, this new model revealed that the entire asteroid is not broken by the impact as the broken fragments (strong gravitational pull) were distributed over the large, damaged core. Prior to this research, scientists believed that what remains behind an asteroid collision is nothing more than a collection of weak fragments loosely held by gravity. However, the results showed that the target asteroid didn’t deteriorate completely. It was a clear indication that more energy is needed for ultimate destruction. El Mir talked about the importance of this simulation and 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.”