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People are probably safe from a catastrophic asteroid strike … for now

If you ever clean the gutters of your roof, note the following: The dirt you throw may be from outer space.

  Book Cover by Cosmic Impact

The new book "Cosmic Impact: Understanding the Threat to the Earth of Asteroids and Comets" by Andrew May (Icon Books) provides an overview of the potential dangers we may one day encounter with near-Earth objects ( Near Earth Objects, NEOs), and on a smaller scale finds that objects fall from space to the earth is a daily occurrence.

"On an average day, about 100 tons of meteorite dust fall on the planet," writes May. "One of the best places to find it is on non-porous surfaces such as city rooftops and gutters. , , The mud in your gutter will almost certainly contain some particles that come from outer space. "

Dust particles from space do not expose the planet and its inhabitants to deadly danger. Asteroids like the ones that made the dinosaurs die out are the most worrisome.

The 124-mile Chicxulub Crater near the Mexican Yucatan Peninsula was forged 66 million years ago when an object 69 miles in diameter entered space from space. The resulting fire and dust, the latter covering the Earth's atmosphere and shielding the sun, eventually killed the dinosaurs.

If we met a similar object today, the result would be similar.

"The devastation would be so much greater than anything that occurs in human experience that it is hard to imagine," writes May. "If the impact were in the ocean, the water would boil. If it were on land, large areas would be devastated by firestorms. The dust, whirled up by a Chicxulub-sized impact, would prevent sunlight from reaching the Earth's surface for months – maybe even years. "

The good news, however, is that the likelihood is great that such an object in our lives on Earth will hit near zero.

The Torino scale takes into account the size of the NEOs and the likelihood that they will hit Earth over the next hundred years to estimate the potential danger on a scale of 1 to 10.

At present the coming century looks so safe.

"There is currently no known object with a Torino rating of up to 1," writes May. "Everything we know is either too small to do any harm, or it's unlikely to be in the next collided with the earth for a hundred years. "

However, this was not always the case. Only in 2004, an object was discovered that had a worrying Torino number of 4, indicating a decent contact opportunity, which would lead to an innumerable destruction.

  A general view of an asteroid towards Earth.
Getty Images] When scientists discovered a 350-meter asteroid this year, they calculated a probability of more than 1 percent that it would collide with Earth in 2029. Given its size, this would have led to an explosion far into the "thousand-megaton class". (By comparison, May writes that the atomic bomb explosions over Hiroshima and Nagasaki each amounted to about 0.02 megatons.)

Fortunately, subsequent calculations have "refined orbit and eliminated a collision," writes May.

is a planet-splintering asteroid currently zero, space swirls with smaller objects that, while not threatening humanity, can still cause real damage.

In fact they already have.

largest cosmic impact in recorde d history ", when a" small rocky asteroid or possibly a small comet ", which was later estimated at 30 to 70 meters, exploded over the" sparsely populated Tunguska valley in Siberia ".

An explosion a thousand times stronger than the bombs used in Hiroshima and Nagasaki did not kill anyone.

"When the Tunguska object entered the Earth's atmosphere, [there] was an explosion of the order of 10-15 megatons – typical of a nuclear weapon of the Cold War," writes May. "The most obvious effect was 80 million trees within a radius of 30 kilometers to singe and clad Tunguskas & # 39; ground zero & # 39; s. "

May quoted a scientist named Gerrit Verschuur, who wrote: "Estimates of the losses that would result from a Tunguska-like event in a populated area – suggest up to 5 million deaths."

The possible However, the effects of a smaller, non-planet-destructive NEO are not all negative, as comets can and may have been providing important resources for our planet

May again cites Verschuur, who wrote in 1996, "A dozen massive comets carry enough water and organic Molecules to deliver all the water and biomass of the Earth. "This may also apply to some asteroids and meteorites. [19659004] May indeed writes that a" significant portion "of the earth's water and organic organisms are exactly on

He notes that when a meteorite landed in Australia in 1969, "At least 15 different species" were found by amino acid as well as a significant amount of water – about 10 percent by weight. "

" impact. , , were much more abundant in early Earth history, "he writes. "So it's not unreasonable to imagine that they brought with them much of the raw material needed to educate and develop life."

Given that a NEO collision with Earth would rather destroy than create life, the United States is watching these NASA is constantly looking at the sky with large telescopes from points in Arizona and Hawaii. But even this defense carries risks.

In February 2013, astronomers identified an asteroid they baptized 367943 Duende who passed close to Earth but made no contact.

Some skeptics thought the asteroid would make us certainty despite the scientists, which is not uncommon. When "a huge meteor exploded over Chelyabinsk [Russia] that day", the skeptics felt confirmed.

  A forest is in ruins, 45 years after a meteorite struck Earth in Russia in 1908.
A forest lies in ruins 45 years after the impact of a meteorite in Russia in 1908. AP

But the scientists were right about Duende. It turned out that the meteor that exploded was a completely different one, which they did not notice because it came "from the direction of the sun," meaning that it was "only in daylight over the horizon when telescopes used it could not see. "

" This blind spot around the sun is a constant irritation to NEO hunters, "writes May." You just have to hope that anything that hides there comes out before it hits us. "

Though there is no way to defend against an object we never see, there are options if a NEO should be discovered on a direct path to Earth to defend Earth. Again, they are all risky.

An asteroid can be destroyed by the detonation of a nuclear weapon, but the many resulting fragments would continue in the same orbit, making the recoil as potentially harmful as the avoided hit. [19659004] For that reason, it would be much more likely that scientists would try to distract the object in order to eject it from its orbit.

The NEO would have to be pushed out of orbit or its speed changed. Neither the direction nor the speed would matter. Anything that would change the course of the object significantly would prevent it from making contact.
The keyword there, however, is "significant."

"An NEO that's big enough to worry about will be much more massive than anything we're used to pushing around," May writes.

"A 1-kilometer rock equals more than a billion tons – or something like 10,000 aircraft carriers. How can we put that into a new orbit, even if it's just a small amount?


An answer brings us back to the nuclear option.

The hydrogen bomb pioneer Edward Teller suggested: In this scenario, a nuclear explosive would land on the object itself, as the force of the detonation would drive it out of orbit. Unfortunately, this would require that "a spaceship adjust the speed to the asteroid and land on it".

This would take years and leave the project open for all possible complications.

Others have suggested that the device explode nearby The object could have the same effect instead of editing it. However, given the risk – and the fact that sending a nuclear device into space would violate several international treaties – it is unlikely that this method will be used any other propellant that can be directly impacted. [NASA 2005] When NASA sent a probe on a passing comet, it was supposed to inspect it and not divert it. But the speed it reached changed the comet's orbit by 0.00005 millimeters per second, giving the tactic credibility on demand.

Fortunately, as mentioned earlier, this is most likely an academic opportunity. A NEO large enough to cause significant damage to Earth in our lives is virtually nil.

Unless we lose it naturally in the sun.

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