Large Asteroids Are a Lot Harder to Destroy Than Previously Thought

While blockbuster Hollywood films often offer simple solutions to fantastical problems, the truth tends to be far more complicated.

For example: remember the massive comets from “Armageddon” or “Deep Impact” that threatened to usher in mass extinctions? All our intrepid heroes had to do was launch some trusty high-yield American nuclear warheads at the pesky meteor, or detonate some bombs, and the disaster was averted–NASA and our favorite movie stars saved the day!

According to a new Johns Hopkins study due to be published in the March 15 issue of the solar studies journal Icarus, large real-life asteroids would be far more difficult to destroy than Hollywood purports.

While the new study may disappoint fans of old asteroid flicks, its findings offer some important information that will be crucial in devising large asteroid deflection as well as impact strategies, in addition to our overall understanding of how solar systems form and how asteroids may one day be successfully mined.

Scientists utilized new computer modeling techniques to simulate an asteroid of about a kilometer in diameter striking directly into a 25-kilometer diameter target asteroid.

The simulation aimed to repeat one that was carried out in the early 2000s, which used inputs like mass, temperature and material density to calculate the result of an impact. Results from the first simulation showed the target asteroid completely shattering upon impact with the smaller one.

The newer model, however, shows that the larger, city-sized asteroid would actually retain its strength.

The paper’s first author, Charles El Mir of the Johns Hopkins University Department of Mechanical Engineering, 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.”

The simulation involved two separate phases.

The first phase evaluated the immediate impact of the asteroid, which resulted in millions of cracks forming throughout the larger asteroid and the creation of a crater. Unlike in the previous test, the asteroid remained intact, mainly thanks to the gravitational pull exerted by its powerful core.

In the second phase of the simulation, the effect of gravity on the impacted crater resulted in the reaccumulation of the fragmented asteroid around the damaged core–a process that lasted several hours.

El Mir noted:

“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.” 

Our planetary history has long been intertwined with the broader workings of the solar system, with many scientists now believing that the Earth and our moon came into being thanks to a massive collision with an ancient planet.

Smaller asteroids frequently strike Earth in a dramatic fashion, as was the case when a spectacularly bright and loud meteor shook residents and tourists in the Cuban region of Pinar del Rio on February 1, 2019. The event recalled the Chelyabinsk meteor of February, 2013, which caused damage and shock across a populated area in western Russia.

“We are impacted fairly often by small asteroids, such as in the Chelyabinsk event a few years ago,” noted the study’s co-author, K.T. Ramesh, who also is the director of the Hopkins Extreme Materials Institute.

Ramesh added:

“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.”