Asteroids are stronger, harder to destroy than previously thought

Asteroids are stronger, harder to destroy than previously thought
Frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact. Credit: Charles El Mir/Johns Hopkins University

A popular theme in the movies is that of an incoming asteroid that could extinguish life on the planet, and our heroes are launched into space to blow it up. But incoming asteroids may be harder to break than scientists previously thought, finds a Johns Hopkins study that used a new understanding of rock fracture and a new computer modeling method to simulate asteroid collisions.

The findings, to be published in the March 15 print issue of Icarus, can aid in the creation of asteroid impact and deflection strategies, increase understanding of solar system formation and help design asteroid mining efforts.

"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," says Charles El Mir, a recent Ph.D graduate from the Johns Hopkins University's Department of Mechanical Engineering and the paper's first author.

Researchers understand physical materials like rocks at a laboratory scale (about the size of your fist), but it has been difficult to translate this understanding to city-size objects like asteroids. In the early 2000s, a different research team created a into which they input various factors such as mass, temperature, and material brittleness, and simulated an asteroid about a kilometer in diameter striking head-on into a 25-kilometer diameter target asteroid at an impact velocity of five kilometers per second. Their results suggested that the target asteroid would be completely destroyed by the impact.

The first phase of a new asteroid collision model, which shows the processes that begin immediately after an asteroid is hit -- processes that occur within fractions of a second. Credit: Charles El Mir/Johns Hopkins University

In the new study, El Mir and his colleagues, K.T. Ramesh, director of the Hopkins Extreme Materials Institute and Derek Richardson, professor of astronomy at the University of Maryland, entered the same scenario into a new computer model called the Tonge-Ramesh 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.

"Our question was, how much energy does it take to actually destroy an asteroid and break it into pieces?" says El Mir.

The simulation was separated into two phases: a short-timescale fragmentation phase and a long-timescale gravitational reaccumulation phase. The first phase considered the processes that begin immediately after an asteroid is hit, processes that occur within fractions of a second. 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 reaccumulation occurring over many hours after impact.

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. This phase of the model examined the individual cracks and predicted overall patterns of how those cracks propagate. The new model showed that the entire asteroid is not broken by the impact, unlike what was previously thought. Instead, the impacted asteroid had a large damaged core that then exerted a strong gravitational pull on the fragments in the second of the simulation.

The second phase of a new asteroid collision model, which shows the effect gravity has on the pieces that fly off an asteroid's surface after impact. This phase occurs over many hours. Credit: Charles El Mir/Johns Hopkins University

The research team found that the end result of the 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. 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.

"It may sound like science fiction but a great deal of research considers asteroid collisions. For example, if there's an 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," adds El Mir.

"We are impacted fairly often by small asteroids, such as in the Chelyabinsk event a few years ago," says Ramesh. "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."


Explore further

Asteroid-deflection mission passes key development milestone

More information: Charles El Mir et al, A new hybrid framework for simulating hypervelocity asteroid impacts and gravitational reaccumulation, Icarus (2018). DOI: 10.1016/j.icarus.2018.12.032
Journal information: Icarus

Citation: Asteroids are stronger, harder to destroy than previously thought (2019, March 4) retrieved 23 May 2019 from https://phys.org/news/2019-03-asteroids-stronger-harder-previously-thought.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
3753 shares

Feedback to editors

User comments

Mar 04, 2019
Obviously the best strategy if time permits is to harvest the asteroid rather than resort to ballistic deflection. The best way we could do this involves either first going to the moon and harvesting some of it's millions of tons of crater water ice or finding any large water ice concentration asteroid. In other words we need gather water ice in space first. Why? Because if we have water ice we can make heated mud. Heated mud is important as it can be the glue we use to patch together small chunks of asteroids together. Large dangerous asteroids can be disassembled with a swarm of autonomous mining drones into more manageable and portable chunks. We can then tote these chunks to a stable lagrange point where we can use specialized heated mud spewing drones to patch together and reform the asteroids substrate. And I'm just talking about basic stock piling here. What you do with the asteroid strata is another awesome subject. Space habitats anyone?

Mar 04, 2019
I think there's something wrong with the asteroid in the 2nd movie: it doesn't spin.

Mar 04, 2019
Obviously the best strategy if time permits is to harvest the asteroid rather than resort to ballistic deflection.

You don't really understand how delta v works, or what kind of masses we're dealing here with - do you?

Mar 04, 2019
Allright doomsayer calm down. Read the sentence first: "if time permits".

Mar 04, 2019
Sounds like photonic pressure is the way to go to avoid making the situation worse.

Mar 04, 2019
Shaped projectiles without exit wounds are also a possibility for less messy kinetic deflection

Mar 04, 2019
I'm not sure about relying on mud in desiccating vacuum? Should be some way to vacuum test it here on Earth?

I favor the idea of nano-bucky filaments entwined in synthesized spider webbing. Maybe larval or plant silk?

If it could be strong enough to hold the rubble together against steering vector forces?

Mar 04, 2019
I was sitting on the crapper pondering when a thought rudely interrupted.
"Straw in Mud!"

Mix long, tangled filaments of nano-bucky strands into the liquid mud. Which could then be pumped & sprayed where useful for at least a short while.

I do not see a whole lot of applications. The one that springs forth ...

Orbital or Lunar Surface Emergency vehicle carrying a supply of n-b mud.

An orbital habitat or Lunar base gets hit by a shotgun blast of space rocks? The survivors inside will have a very difficult time repairing hull integrity & restoring pressure, in order to reach trapped victims w/o p-suits in their sealed compartment.

The Emergency pumper sprays the mud over the outside of the damage to support rescue efforts inside,
It just has to hold until the habitat is evacuated & tugged to a dockyard,

Now you boys wouldn't be thinking of cheating me with a "Dirty-Clarke" by patenting this before I do?!?

Shame! Shame on you!


Mar 04, 2019
CAPTURING an asteroid, to mine it, is not necessarily the complicated part, it's mostly just orbital dynamics and delta-v, etc. RATHER, reducing / mining / smelting rocks into usable material? That's where the challenge comes in. Small robots can scoop, sure, but energy to melt and thus smelt (separate elements) is significant. One idea would be to spin up a sample in zero-g, focus a big mirror on it and melt the sucker. Centrifuge-effects put the dense atoms on the outside, helpfully trapping some of the gasses in the center. A melted-slag object, spun VERY rapidly, would differentiate and simplify mining.

Mar 04, 2019
Mud has it's uses though. Think about transporting in general. Instead of hauling a slurry of loose asteroid sediment, why not turn it all into mud clods on the mother asteroid. Then use robotic drones with hefty ions to grab and throw them into space.

You could have a line trail of mud boulders steadily traversing the void to a receiving station, where they would be grabbed up by similar hefty ion drones.

Mar 04, 2019
Then like JustAnyone said, "focus a big mirror on it" and stick it on the stock pile.

Should stick.
Maybe? I dunno

Mar 04, 2019
Could just ram them into the moon or mars for later use. Repeatedly ramming asteroids into Mars at high speed is one of the plausible lower-tech ways we could conceive of terraforming a planet. Particularly if we can identify objects with favorable water or element mixes toward atmosphere.

Mar 04, 2019
A popular theme in the movies is that of an incoming asteroid that could extinguish life on the planet, and our heroes are launched into space to blow it up.

I'd have to say this is incorrect. The popular theme in movies when it comes to asteroids on a trajectory course intersecting with Earths is governmental bodies preparing to launch nuclear weapons to destroy an asteroid, while a scientist or a group try to warn and persuade against such an attempt citing that the nukes will either not destroy nor alter the asteroids trajectory, or will cause the asteroid to split into parts which will still impact the Earth except now in even more places on the globe. The scientists usually plan on altering the trajectory of the asteroid by using gravity tug or some other trajectory altering methods.

Not that Armageddon doesn't exist, or that it isn't a popular movie, just that the theme of Armageddon is not a popular one when it comes to movies involving asteroid ELE's.

Mar 04, 2019
Mud has it's uses though.


Not possible in a vacuum to maintain any liquid on that surface.

Mar 04, 2019
It's been a lot of years since I helped friends build an adobe home. It took a hell of a lot of work shovel a lot of dirt, mix in an exorbitant amount of water, & pound the bricks solid.

The crew jefe warned us to be cautious as we piled the bricks into walls. Adobe does not have any tensile strength. & couldn't be trusted until all the walls were locked around a wooden frame for support.

That's why my suggestion to use it for a temporary emergency slap & dash. When the damage is random, widespread holes.

The water will be sucked out by the vacuum & boils away. You will need to do a cost-analysis including the delta-v it would take to move & stop such an unwieldy product.

If Human lives are not at stake? Other materials would prove way more cost effective.

Also water in orbit is damn near irrecoverable once released to Space. You need water were you need it, when you need it. Delivery to your habitat from Trojan's orbit in ten years?
Don't be a denier wastrel!

Mar 04, 2019
I know that when astronauts send their pee into space it immediately vaporizes and freezes into fine particles. The reason why it vaporizes is obvious, there is no pressure in space. The reason why it freezes equally as fast is because the water vapor expands allowing the individual molecules to lose their heat, even though water is an excellent heat retainer as a liquid.

Mud and heated mud are compounds. They are not pure water. Would it react like pee does?

As far as I know, no one has ever experimented with it in the vacuum of space and published results. I think heated mud would have little icy snaps, and pops on its surface but would still be a workable mortar. Sludge is a thing in space. Ceres the asteroid is said to be filled with it.

Mar 04, 2019
"Frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact..."


This is exactly why the "Moon formed by a collision into earth" theory goes nowhere. Anything ejected from the earth would have been brought right back by gravity. This nonsense about fragments joining to make a moon is just plain silly. There is no science behind it.


Mar 05, 2019
"Frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact..."


This is exactly why the "Moon formed by a collision into earth" theory goes nowhere. Anything ejected from the earth would have been brought right back by gravity. This nonsense about fragments joining to make a moon is just plain silly. There is no science behind it.

says Bart

It depends on how high in altitude the fragments traveled away from Earh and at what velocity they traveled. A really huge object colliding with the Earth at just the right angle could do it.

Mar 05, 2019
Surv, you live in a world of fantasy. Don't give meaningless comments, without showing the math and physics involved. If you can't back up your assertions, then don't make such claims.

Mar 05, 2019
Could just ram them into the moon or mars for later use. Repeatedly ramming asteroids into Mars at high speed is one of the plausible lower-tech ways we could conceive of terraforming a planet. Particularly if we can identify objects with favorable water or element mixes toward atmosphere.

And why do you think that is feasible or even affordable? Why do you assume diverting asteroids potentially 100s of millions of miles off course is so easy? The ignorance in your question especially when it's clear you think you are asking a smart question is astounding!

Mar 05, 2019
"Frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact..."


This is exactly why the "Moon formed by a collision into earth" theory goes nowhere. Anything ejected from the earth would have been brought right back by gravity. This nonsense about fragments joining to make a moon is just plain silly. There is no science behind it.


Your comment is science-free. I do understand though. You think your gut instinct is superior to some of the most brilliant minds on the planet and farts out pure genius that trumps any of the nonsense those silly scientists say with their fake PhDs from leading universities.

Mar 05, 2019
Jon I think SciTechdude was responding to my idea about the steady traversing trail of grabbed and thrown boulders. Which is in fact something that was going to be developed by Nasa if only in essence. It was the capability of the plan B robotic vehicle of the recently canceled and defunded ARM mission.

Mar 05, 2019
The ARM mission was actually fully funded by President Obama's team towards the end of his tenure but it got scrapped and the contracts were closed out when Trump's team came in. Trump's team wants NASA to focus more on moon industrialization, which isn't necessarily a misstep because we do need water ice in space, but they shouldn't have closed out the ARM mission in the process imo.

Mar 05, 2019
I think NASA was going to put some beefy ions on that vehicle, maybe the a2 or the new hydrogen MPD (magnetoplasmadynamic) thruster. In all, it would have been some really good science.

Mar 05, 2019
Jonseer, no, physics is on my side. What goes up comes down. You surely know how much energy has to be expended to get satellites into orbit. Such motion does not come of its own. It is up to collision-made-moon-happen thinkers to come up with a physics explanation for such nonsense. So far there is none.

Mar 05, 2019
Some commentators in the past have quoted to me some scholarly articles about such theories, but the ones they pointed to started with the premise that the ejected material somehow started to rotate around the earth, and offered no explanation for how that happened.

Mar 05, 2019
Here are some hypothesized pic links of Asteroid Retrieval Robotic Mission (ARRM) spacecraft:

https://upload.wi...lanB.jpg
https://upload.wi...on_B.jpg
https://upload.wi...on_B.jpg

Mar 05, 2019
Also water in orbit is damn near irrecoverable once released to Space. You need water were you need it, when you need it. Delivery to your habitat from Trojan's orbit in ten years?
Don't be a denier wastrel!


Who said 10 years? Let me make my spherical regolith covered base with a jack shaped 14 centrifuge habitat core that allows me to control the base's entire axial spin and orientation and I'll railgun you superconductive ice pellets in a rainstorm. Think about it..Rain in space. (cue the blade runner music). You'll get it in about 2 weeks, just make sure your target is out and has the right density. I don't want anything blowing out the back like last time.

Mar 05, 2019
The Thela Impact hypothesis, is.
During an early stage for our Solar System, there were a many interplanetary furballs as the disks of debris were being cleared out by the larger masses.

Thela is speculated to have been a Mars-size planetoid that ran right into the early Earth.
The resulting collision had enough force to drive Thela into the Earth's crust & mantle.

This process is Newtonian physics. Nothing exotic except for a random minor crash.

The Earth's Mass was increased from the large Mass it ripped away from Thela.
Thela may have torn off some Earth crust?

Remember, Equal & Opposite Reactions?
The core of Thela got whipped off into orbit around the Earth, to become the core of our Moon.

Between the two molten planetoids were gigatons of wreckage being strewn in all directions.
The Earth's greater Mass would have pulled much of it down to add to it's crust.
Thela got some, the rest was kicked away & where that went? No body knows. Yet.

Mar 05, 2019
As a Republican I demand that this is not a problem.

Mar 06, 2019
Deflection will be easier than destruction.

And obviously, identifying NEOs earlier enough for effective deflection gets easier with more lead time, and thus more orbits with which to make minor tweaks. . .

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more