Research shows why meteroids explode before they reach Earth

December 11, 2017, Purdue University
Credit: CC0 Public Domain

Our atmosphere is a better shield from meteoroids than researchers thought, according to a new paper published in Meteoritics & Planetary Science.

When a meteor comes hurtling toward Earth, the high-pressure air in front of it seeps into its pores and cracks, pushing the body of the meteor apart and causing it to explode.

"There's a big gradient between high-pressure air in front of the meteor and the vacuum of air behind it," said Jay Melosh, a professor of Earth, Atmospheric and Planetary Sciences at Purdue University and co-author of the paper. "If the air can move through the passages in the meteorite, it can easily get inside and blow off pieces."

Researchers knew that meteoroids often blew up before they reach the Earth's surface, but they didn't know why. Melosh's team looked to the 2013 Chelyabinsk event, when a exploded over Chelyabinsk, Russia, to explain the phenomenon.

The explosion came as a surprise and brought in energy comparable to a small nuclear weapon. When it entered Earth's atmosphere, it created a bright fire ball. Minutes later, a shock wave blasted out nearby windows, injuring hundreds of people.

The meteoroid weighed around 10,000 tons, but only about 2,000 tons of debris were recovered, which meant something happened in the upper atmosphere that caused it to disintegrate. To solve the puzzle, the researchers used a unique computer code that allows both solid material from the meteor body and air to exist in any part of the calculation.

"I've been looking for something like this for a while," Melosh said. "Most of the computer codes we use for simulating impacts can tolerate multiple materials in a cell, but they average everything together. Different materials in the cell use their individual identity, which is not appropriate for this kind of calculation."

This new code allowed the researchers to push air into the meteoroid and let it percolate, which lowered the strength of the meteoroid significantly, even if it had been moderately strong to begin with.

While this mechanism may protect Earth's inhabitants from small meteoroids, large ones likely won't be bothered by it, he said. Iron meteoroids are much smaller and denser, and even relatively small ones tend to reach the surface.

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cantdrive85
2.3 / 5 (12) Dec 11, 2017
Again just GIGO, a code that ignores the electric potential difference of the bolide and Earth's atmosphere is meaningless mumbo jumbo. The bolide is similar to an exploding capacitor in this situation, and it easily explains the tremendous energy released not to mention the electrophonic response among other phenomena.
Chris_Reeve
Dec 11, 2017
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Gigel
1 / 5 (2) Dec 11, 2017
I wonder if this applies too to highly rotating (rolling) meteorites. An asymmetrical one may be made to rotate faster and faster as it enters the atmosphere, especially if it does so at a steep angle from the vertical, which would give it a long path through air. This would also give it a vertical force due to the Magnus effect, which would be buoyant ore infalling, depending on the way it rotates. Then the meteorite could come horizontally and fall very slowly, while also greatly increasing its speed of rotation. That could make it very dangerous, as it may survive to ground level.
Gigel
3.7 / 5 (3) Dec 11, 2017
@cd85: what is the potential difference for a typical small meteorite that would ensure alone the explosion comparable to a small nuclear bomb?

How much can you charge say a metal sphere until its charge starts flowing into vacuum, leaving said sphere?
rrwillsj
3.3 / 5 (8) Dec 11, 2017
"Thundermugs to the right of me!"
"Thundermugs to the left of me!"

"Bravely I charge into the dank valley of EU corybantics!"

You guys are getting a decent group discount for your therapy sessions?

I'm still waiting for an un-photoshopped image of a meteor fall, displaying any EU Whoopsie lightning bolts.

G, the answer to your question is friction heat. A feather pillow hitting the Earth's upper atmosphere at tens of thousands of miles per hour? Is going to flame, Baby!

After hundreds of years of telescopic observation of the Moon. There has never been seen a meteor fall. No atmosphere to crash through.

If there was any possible Universe in which EU whoozie was possible? We wouldn't need telescopes. The cosmically crackling chitlins would often be visible to the naked eye.

It's that damn invisibility cloak, malicious godlings are casting. To deliberately embarrass the saintly worshipers of EU theology.
Chris_Reeve
Dec 11, 2017
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691Boat
4.6 / 5 (10) Dec 11, 2017
It seems straightforward that if the hypothesis put forward in the article is true, then all meteorites should explode at around the same height, no?

It seems straightforward that if gravity is true, all planes should crash the same, no?
Solon
2.4 / 5 (5) Dec 11, 2017
Is electric charge separation the main process for kinetic energy transformation into the meteor phenomenon?
https://www.aanda...-08.html
RealScience
5 / 5 (7) Dec 11, 2017
It seems straightforward that if the hypothesis put forward in the article is true, then all meteorites should explode at around the same height, no?


The height would depend strongly on the consistency of the meteoroid. Compared to a porous ice/gravel agglomerate meteoroid, a solid nickel-iron meteoroid would typically have lower porosity, and thus less internal void to pressurize and thus less force, as well as much higher cohesive strength.

The height would also depend somewhat on the velocity, size and angle of descent, which determine how much of the air can get out of the way to decrease the high pressure. And large objects would merely have surface layers blown off.
barakn
5 / 5 (4) Dec 12, 2017
Is electric charge separation the main process for kinetic energy transformation into the meteor phenomenon?
https://www.aanda...-08.html

Nice find, Solon. Of course the charging mechanism in this paper is produced by the motion of the meteoroid itself and doesn't rely on any external electric fields or currents to cause the explosions, so it doesn't advance EU any further. After claiming that other mechanisms quantitatively could not explain the power involved in other observations, they admit that "We were not able to find theoretical or experimental data on the tribo effects of solids moving with hypersonic velocities in gases, so we are not able to present any quantification so far." And that's what makes this a weak paper.
Chris_Reeve
Dec 12, 2017
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Chris_Reeve
Dec 12, 2017
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cantdrive85
1.9 / 5 (9) Dec 12, 2017
"We were not able to find theoretical or experimental data on the tribo effects of solids moving with hypersonic velocities in gases, so we are not able to present any quantification so far." And that's what makes this a weak paper.

The weakness of this situation is regarding lack of scientific research efforts regarding electrical effects, these scientists just found what has been pointed out for some time. This is why EE POV are more relevant when it comes to these phenomena (including space research) because we are dealing with plasmas and charged objects and such.
rrwillsj
3.3 / 5 (3) Dec 12, 2017
Just a quick thought. If the EU claims of electrical effects versus the theories of gravity and mechanical effects, is a better explanation? Claiming that the electrical effect is Universal.

Than how can there be any visible difference between observations of meteor falls through an atmosphere or through vacuum? And where in the heck does all this asteroidal rock, that keeps falling on our heads, come from?
RealScience
5 / 5 (4) Dec 12, 2017

I'm not quite getting why a porous ice/gravel agglomerate would explode at all. It should just come apart and disintegrate, no?


Even well below the melting point of a material, atoms and molecules migrate. Ice is particularly good at migrating to 'cement' things together, so an agglomeration will build some cohesive strength (ice near the surface can evaporate and leave loose rubble).

A ruble pile grazing at 20 km/sec will simply disintegrate. But picture a non-cohesive pile of gravel 10 meters in diameter hitting the atmosphere straight on at 100 km/sec. It would go from near vacuum to sea level in less than a second, and encounter roughly its own mass in air along the way, which it compresses and heats.

Whether the energetic disintegration of a 10-meter rubble pile in a fraction of second is an 'explosion' is semantics. But an explosion is typically a brief event driven by the rapid expansion of dense, hot gas, so the term seems applicable.

Chris_Reeve
Dec 12, 2017
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Chris_Reeve
Dec 12, 2017
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Chris_Reeve
Dec 12, 2017
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Chris_Reeve
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Da Schneib
3.7 / 5 (6) Dec 12, 2017
@Chris_spam is real upset someone who knows what they're talking about here got cred.
Chris_Reeve
Dec 12, 2017
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Chris_Reeve
Dec 12, 2017
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krzychu01230
2.3 / 5 (3) Dec 13, 2017
Energy released in deep impact was puzzling for mainstream; energy amount released by disintegration of Chelyabinsk meteor was expected by pure mechanical hypothesis?
Maggnus
4.2 / 5 (5) Dec 13, 2017
Wow, lookit Chis.Reeve gish-gallop along!
rrwillsj
4 / 5 (4) Dec 14, 2017
If C_R and the other EU Woohooie cranks, were any where in the vicinity of correct and sane?

We need to reopen and rededicate the Temple Pyramid of Tenochtitlan to preforming mass human sacrifices.

Cause hey! People love to repeat the stupidity of their ancestors. And, that's gospel!

I would suggest that the "Heroic Floggers of EU Balderdash" go first. Show us dull-minded believers in the heresy of empirical science, how brave they are. How pure their hearts. Sacrificing themselves to convince the godling jokesters not to drop their Thundermugs of Doom upon this world.

Yes, yes, that will solve it all. No need to waste any effort on scientific research when we can join with the EU bunco artists in plagiarizing out-of-context bits of other peoples obsolete textbooks.

And thank you cranks for reviving mis-interpreted, mis-translations of incoherent mumblings by ancient drunks and archaic dopers with dogmatic repetitions of gibberish.

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