Future | Fall asteroid

Sep

13

2013

Meteorite

Asteroids are falling , falling , and will fall to Earth . Large impacts are dangerous, but rare, fine happen frequently. In fact, the smaller the size of the asteroid, the more often they visit our planet. Micrometeorites fall with such frequency that you could build a collection, if you knew exactly where.

Just in 1908 (yesterday in geological terms), a huge explosion rocked the area at the Stony Tunguska River. If you do not know Tunguska is a small river about 65 kilometers from Vanavara in Siberia. The strength of the explosion was such that it can be compared with the explosion of a hydrogen bomb at 10 megatons. This energy is released in the explosion of 10 million tons of TNT. Yes, it was not the hydrogen bomb, and obviously asteroid tens of meters in diameter, which crashed into the atmosphere at ultra-high speed and exploded.

I say “ran into the atmosphere,” because when asteroids approach the Earth, they do so at a speed of about 32,000 km / h Clash of the air at that speed is something like an explosion. Imagine that you have a 15-kilometer route, which can be covered within 20 minutes at a reasonable driving conditions. At the speed of the asteroid it will take 2 seconds. Sounds great, until you weigh the side effects. Have you ever poked his hand out of a car window, hurtling at high speed? The air is remarkably strong pushes his hand, even sickly childhood classmate pushed in the chest weaker. Physics dictates that the air resistance increases sharply with increasing speed. 32,000 kilometers is 300 times greater than 100 kilometers, and hence resistance is your hand to test speed asteroid be 300 x 300 = 90 000 times greater than Sotk kilometers per hour. If your hand weighs a pound, it will test 40,000 kg of resistance, if you will pop it out of the asteroid.

40,000 pounds – it’s full potential as a freight train loaded with coal, and your hand will be smeared out instantly. That is why the resistance destroys most of the meteorites in the air before they reach the ground. Resistance makes their energy of motion into heat, so meteors explode. Tunguska event could well destroy the city. Fortunately, the explosion happened in a remote forest area, damaging a few hundred square kilometers. Even taking into account the power of the Tunguska meteorite explosion was just zilch compared to what could happen.

Large asteroids can long resist the atmosphere before you crash into the ground. The result could be an impact crater, which will turn to dust and lift up the atmosphere so much stone that climate change significantly, perhaps for months, and around the world. One of these collisions, it is believed, killed the dinosaurs 65 million years ago when an asteroid dinol hit the ground near the town of Chicxulub in the Yucatan Peninsula in Mexico. Some dinosaurs, is to their credit, have survived and lived to see this day. We call them birds. A subset of these dinosaurs we call hummingbirds.

Not so long ago, and, fortunately, a very small asteroid fell 49,000 years ago. Being 1.2 km in diameter, he formed the “most well-preserved meteorite crater in the world.” In Arizona, the company owns Barringer Crater, perhaps, the only legitimate company crater in the world. There are several other companies that will sell you the craters and other pieces of land on the moon and other planets, but in accordance with the international convention of the laws, they do not actually own them, and therefore can not sell.

These companies sell only evidence of ownership of extraterrestrial craters, and certificate holders may try to exercise that right. These firms are legitimate only as a firm, printing certificates, but not kraterotorgovtsy.

Crater, owned Barringer Crater, which, by the way, is called simply “crater”, has become a tourist attraction because it does not contain iron billions of dollars, as believed and hoped Berringer old when he bought it in 1903.

The largest impact crater on Earth, as we know, it’s Vredefort crater in South Africa. The crater is 270 km in diameter was formed when an asteroid “Arheoaster” measuring just 5.10 km in diameter, fell to Earth about 2 billion years ago, long before the first dinosaur walked out of the eggshell.

Weather eliminates the impact craters on Earth, so they are not obvious. But here’s the moon dotted with numerous craters, which are clearly visible in the telescope, since this satellite of the Earth there is no atmospheric winds and surface water. It would be logical to note that large bodies are often “on the fly”. Not least because they take up more space, and therefore have a greater potential to intercept the asteroid’s orbit.

In addition, large bodies have a stronger gravity, which tends to suck the coming asteroids as ventilation. The largest body next door to us is the sun . Of course, in light often something falls. 1 and 2 June 1998 two comets crashed into the Sun, triggering coronal mass ejections, their size is much greater than the Earth as a whole. The largest body of the solar system after the Sun – it’s Jupiter. In July 1994, the comet Shoemaker-Levy 9 in the form of twenty pieces plunged into the planet for a couple of days. Fall left clearly visible in the telescope dark spots, as well as outbreaks of microwaves, X-rays, ultraviolet, infrared, and radio waves.
Going into the details

Let’s clear up a few terms that are often confused.

Meteoroids – (from the Greek. Meteoron, born air) is less than the asteroid sometimes reach the size of kibble, but often less than a grain of sand.

Micrometeoroids – also called cosmic dust particles are extremely small meteoroids.

Meteors – meteoroids, which entered the atmosphere and burned during the flight. It was this – “shooting stars.” Time make a wish.

Meteorites – pieces of “shooting stars” that fell the same on the ground.

Micrometeorites – it micrometeoroids that fell to Earth. Micrometeoroids do not burn completely, because they are so small that they cool down very quickly and lose heat. Scientists have discovered deposits of high-quality micro-meteorites in polar ice and snow. You yourself can collect micrometeorites from roofs and other sources using a magnet, paper, and a microscope.

Asteroids – (literally, “star-like”) is a stone or iron planetoids, especially within the Jovian orbit.

Comets – a lot like asteroids, but they present the ice. Comets formed far from the Sun, where it is cold, and they contain a fusible substance like ice. They leave the tail, flying toward the sun as it roasts them, and they are losing ice. We wrote in detail about the differences between an asteroid from a comet .

Fireballs – for astronomers is particularly bright meteors – fireballs! For geologists race cars are asteroids or comets that have fallen and left a crater.

What can we say about the collisions that did not occur, but one day may happen? Stony Tunguska event has tumbled down about 80 million trees – or would destroy the city. The car, which created a “crater” in Arizona was far more devastating than the Tunguska meteorite, spray yourself iron rain on the local area. Fortunately, the impact of this magnitude are rare. But they do happen. Father of all collisions, by the way, did not leave a crater today. When the Earth was young, there was a gargantuan collision with a huge asteroid, believed by many. He came into our planet at high speed, tearing a huge chunk out of it and threw it into orbit. Thus was formed the Moon.

Is the Earth any scars of this cosmic apocalypse childhood? Perhaps the unusual minerals formed at a time or currents of molten rock that formed at the time and still present deep below the surface. These currents may well explain the current facts like “hot spots” within the Earth, such as the one under Yellowstone National Park, which erupt every few hundred thousand years (yes, that’s about it in the movie “The Day After Tomorrow”), or sverhvulkanov from which Pompeii die. We do not know yet.
“Apophis” – hi-stone of the future

Lake at the Stony Tunguska

Events, which are produced as a result of the moon in our own solar system is expected. But the program of near-Earth objects NASA (NEO) gets steadily more information about what kind of scale events await us in the future. Here, for example, 13 April 2029 an asteroid Apophis will approach Earth at a distance of 45,000 kilometers. If he’s going to hit, it would free up 510 megatons of energy. This is 10 times more powerful than the “Tsar Bomba” – the biggest of the thermonuclear bomb tests on which ever threaten humanity, and of Russian, of course. And it is 50 times more powerful than the Tunguska explosion. If Apophis will arrive in a large populated area will no longer be a major populated areas.

Of course, 45,000 miles – it will not go to the store. Accidental passage of the asteroid at a distance, probably will not hurt the people of the planet Earth – but all of a sudden? What is the probability that the random asteroid landed yet? The issue, in fact, from the category of what are the chances that a dart dart hit the bull’s eye target.

Here is an analysis.

The diameter of the Earth – 12,743 km. The diameter of the large circle in the 45,000 km from the surface of the Earth is 45,000 km away from the circle, personifying the Earth’s surface, plus 6,400 km from the center of the Earth, plus 6,400 km to the other end of the Earth, plus 45,000 miles to the other face of the bigger circle. It is 100 000 km, or 8 diameter of the Earth. Recall area of ​​a rectangle, circle, or any other figure proportional to the square of the length of any shape measurement.

Our planet is 1/64 the zone diameter of 100 000 km of the large circle, so the asteroid that randomly moves through this cycle will be one of 64 chances to hit the bull’s eye. If Apophis hit the target in 2029? Maximum Risk – 2.7% (more than 1 in 40). Fortunately, he quickly dropped since the original calculations. New measurements and calculations show that the risks are zero. Moreover, the asteroid will pass within 35,400 miles of Earth. We will avoid the bullets. But we can expect that each of the 64 asteroids, which will take place in the 45,000 km away, can hit the bull’s eye.

Most of the time we were just lucky. For example, additional calculations of astronomers about the time after 2029 showed that Apophis will carry with them into the basket one in a million chance to get on visits to Grandma Earth in 2036, 2068, 2076 and 2013. But are we not constantly take? Asteroid collision may occur, which means that to happen. Even one percent can mean the regional devastation – and that word NASA.

Turin scale Collision – this is the only metric of the risk of collision with an asteroid, designed for general use (although Palermo technical scale of the danger of collision is more used by astronomers). Turin scale was named after the city of Turin in Italy, collected in 1995 and presented at a conference in 1999, guess where. All of the known asteroids on this scale have the status of “0” (not dangerous) than the asteroid 2007 VK184, whose status “1” (the chance of collision is extremely small, there is no cause for public concern.) The highest score – 10: “The Clash is inevitable and can cause dangerous climate change, which threaten the future of civilization as we know it.”
Not only Apophis

More important than the analysis of the likelihood of exposure specifically Apophis will have a better understanding of how to counter any asteroid. In the end, if you have garbage in the back yard, you do not care what it is.

Map

There are about 900 large (1 km or more in diameter) of known near-Earth objects. We showed a beautiful map , which shows all. 92 of them were discovered in 2000, but since then there has been a tendency to reduce the number of new discoveries. In other words, we found most of what there is, and we continue to explore their full inventory. But: there are many other asteroids with a diameter less than a kilometer, but which can cause damage. Remember, as Apophis, and the Tunguska meteorite was less than a kilometer across. Do not also forget the fact that something big could land you on the street tomorrow, spoiling the mood (for a very long time), and violating all metrics. But astronomers bdyat, so in the near future should not worry.

All this is based on a particular angle predicting hazardous body size are stored in the database. Clashes with the size of the Tunguska meteorite occur once in a thousand years, on average. Large impacts are less frequent small – often. The asteroid that sent to the forefathers of dinosaurs may fall once every 200 million years. The events of one kilogram of TNT equivalent to occur three times a day. Explosions meteorites to 1 megaton mostly occur in the sky. “Shooting stars” are in this category.
What do we do?

Hoba Meteorite

The fall of an asteroid killed the dinosaurs. The fall of another may condemn us. Need something to do with it, right? But what? The Association of Space Explorers, which calls itself “an international professional organization of astronauts and cosmonauts,” argues that the protracted discussions can lead to inaction, and the evacuation of the drop zone – our only chance. Evacuation is good, it can damage unless the economy, but to save lives. And there are competitive strategy. It is always possible to estimate the economic costs, to plan, implement, and to rejoice.

Problematic asteroids need to parse. This means potentially dangerous objects, shadowing them to clash could have been predicted for many years before him. This will allow time for the development of effective action. These projects are called observations “Spaceguard,” after Arthur C. Clarke gave a fantastic novel “Rendezvous with Rama” in 1973, and NASA launched them 19 years later in 1992. Later, section 321 NASA set a target in 2005 to detect and characterize near-Earth objects 90% of at least 140 meters in 2020. This goal will be achieved, according to forecasts, a few years later. No matter – the understanding of how to work with hazardous asteroids, is more important than to achieve the goal in time. But awareness of the danger of an asteroid that’s only part of the story. Mitigation of threats is part two. Some methods of neutralizing the threat of an asteroid may work temporarily (for centuries or millennia, for example).

What is here? The repulsion of the body to the side, and it’s not frail classmate, given that rocky asteroid 30 meters in diameter can weigh about 600 000 tonnes, to be at a distance of millions of miles away and fly at a speed of 32,000 km / h This is about 10 km / s. You can not just call a tow truck to pull in the direction of the asteroid. To do this, developed a variety of exotic strategies. All of them so far is not even painted on paper, but already has some of the romance of space a mile away.

To land on the asteroid and set a number of mirrors that concentrate sunlight onto a certain area. A sufficient number of mirrors can vaporize the material. Couples will evaporate in space, asteroid gradually pushing in the opposite direction (according to Newton’s third law).
As above, heat the material, but this time using a powerful laser (solar powered). The laser can not be on the earth, because the line will need to overcome the vast distance, having lost power, the laser will have to carry.
To land on an asteroid spaceship, then use the ship’s engines to nudge an asteroid. The ship has to be turned upside down to make it work.
Absorption and reflection of light causes a small amount of power. For example, when the sun is directly overhead, it pushes square kilometer land surface with a force of about 500 g / km 2. Light pushes perfectly reflecting surface is two times heavier than a perfectly black (absorbent). Furthermore, all objects emit heat at high temperature more or less – low. This produces a slight pull – the Yarkovsky effect. For these reasons, part of paint asteroid black, white or silver color – means to force them to change the trajectory over time. Weak forces will make it long, strong – fast. Explosions, for example, may cause a short and powerful force.
Push the spacecraft with the asteroid. At a speed of 10 km / s collision will cause a massive explosion and, more importantly, change the speed of the asteroid, and therefore its orbit. This hardly helps against asteroid 1 km in diameter and with a density greater than twice the density of water if to push him with a 100-ton ship as it only will delay the time at 35 km / year. But for the asteroid 50 meters in diameter, that is, the size of the Tunguska bolide, the situation is different: the diameter is 20 times smaller, and hence the volume and mass, and the rate of change in 8000 once, that is, it will be 18,000 km / month . Given that the Earth is 12,000 kilometers in diameter, probably, such a move would save the planet.
Blow up something near or under the surface of the asteroid.Or embed it in a big ship with the same purpose. There can be problems if an asteroid falls apart, rather than to change the orbit.
The nuclear explosion, and more, according to NASA, will be more effective. Furthermore, given current technology, it is even possible. But the explosions can simply destroy the asteroid, and will not budge. If you destroy it well enough, you will find yourself flying splinters dangerous new orbit. It is necessary to test experimentally that worked then. If we are able to conduct an experiment, we are quite able to further undermine the dangerous asteroid like Apophis preemptively if humanity will not be enough savvy to meet face to face danger. At the same time will have an incentive to get rid of nuclear weapons , which is stored here on Earth.
Bruce Willis.

While getting rid of the dangerous asteroids looks plausible, the technology is still too cheese to give one hundred percent certainty. The famous astronomer Carl Sagan at all afraid we’ll send an asteroid to Earth, rather than take him. We need to know when and where he will encounter as you can in advance. With 100 or more years left, we will be able to evacuate the area of ​​a meteorite, as well as time to develop methods that will push or destroy guest. Even the big city, you can move or disperse over a hundred years. If Seoul would start moving 50 years ago to leave the area of ​​the North Korean artillery shelling, the case would be half done.

On the other hand, if the warning will be done in a couple of days or weeks, need urgent evacuation. Some cities have to stock up plan in advance. Since a large part of the Earth is covered by water, most of the asteroids will fall into deep water. Like an earthquake, the fall will cause a tsunami. Even a relatively small tsunami destroyed the nuclear power plant in Fukushima in Japan, releasing large quantities of radioactive contamination.

Another devastating catastrophe linked to the Indian Ocean tsunami in 2004 – then killed more than 200,000 people. Stories of floods in different nations (Noah’s Ark) remind us of the need to anticipate disaster. Universe should not be afraid because of the brevity of our lives, but if we are to cope with the disaster of cosmic proportions, you need to act prudently and collectively.
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Tags: Asteroids , The Future , Meteorites .

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