Apophis, risk of impact | | | | | |
| | | | | | |  Automatic translation | | | | | | The space is not empty | | | | Category: asteroids and comets |  | | | | | The interplanetary space is littered with dust and material, dating from the creation of the solar system.
Asteroids and comets are rocky and metallic objects, moving at breakneck speed around the Sun.
Sometimes, their orbits intersect that of a planet or the Earth causing a collision, the speed of moving objects because the energy released by an impact, is terrifying.
Meteorites and comets bombard the Earth from the solar system's birth.
Although they seem quietly installed in their orbits between Mars and Jupiter, they are sometimes destructive and they must likely the emergence of life on Earth.
The asteroids that cross our orbit are called Near Earth Objects.
Apophis, the asteroid small, 270 meters long, could be a threat. In 2012, scientists estimate that one chance in 233 000, the probability that this rock come crashing in the Pacific Ocean April 13, 2036.
Its orbital period is 325 days and it crosses the orbit of the Earth, 2 times per revolution. | | Moreover, we observe carefully the sky and we find more dangers. Since 2004, the list of NEOs increases dramatically.
The observations show it and the astronomers realize that we are currently powerless against these risks.
Millions of asteroids frequent the area of space between Mars and Jupiter.
The Kuiper Belt contains over one trillion comets and there are at least as much in the Oort Cloud.
All these objects are under the laws of celestial mechanics and ballet around the Sun is chaotic by nature. The slightest disturbance is enough to disrupt their orbit. Just such an asteroid undergoes a minimal disturbance passing close to Jupiter so that its path is deflected. The risk of a major impact began to invade the consciousness in the early 1980s when the scientific community was the first evidence that such a catastrophe already happened several times in Earth history.
That risk hangs over our heads like a sword of Damocles. | | 
* The near-Earth asteroids in green are non-hazardous, NEOs in orange are slightly dangerous, NEOs in red are to be monitored carefully. The number of objects actually increases as dangerous as observations. | | | | | | | | Risk of impact with a meteorite | | | | | | | | | | In the early 1990s, astronomers have realized that the stability that prevails in our solar system was only apparent when the French astronomer Jacques Laskar showed that the movement of bodies in space followed the laws of chaos. The consequence is that it is impossible to predict long-term trajectories of objects that inhabit our solar system. It has happened several times and life, every time, has disappeared to 80%.
The power potential impacts give dizzy.
We're talking, of tremendous energy, billions of times that a nuclear bomb.
What's a near-Earth asteroid (NEO) ?
An object that moves around the sun between Mars and Jupiter is an asteroid. A big stone that moves in space and entering the Earth's atmosphere, is a meteorite. Among the asteroids monitored, identified in 2012, 200 to 250 are NEOs. It was not until the 1960s that we have understood what the meteorite craters.
The Moon is riddled with impact craters and the Earth could not escape to this bombing. In the 1980s we will notice an iridium layer several centimeters thick, which covered the entire surface of the Earth, there are 65 million years. | | These traces were noticed throughout all continents without exception.
They correspond to the fall of a meteorite 10 kilometers in diameter, which crashed into the Gulf of Mexico, causing the Chicxulub Crater and the dinosaurs extinction.
However a small object, the size of a mountain, which falls into the ocean, is enough to create chaos on a global scale.
The scenario is well known, the impact causes a huge cloud of dust that will mask the sun's radiation, for months and years, then the plant will die, the food chain is broken and the majority of land animals will die them also.
nota: A shooting star is just a grain of sand, causing a flash so intense that we feel that the object is large but in general it is not bigger than a grain of sand or that a gravel. | | 
| | | | | | | | Apophis, the next disaster | | | | | | | | | | The next potential catastrophe is called Apophis (2004 MN4), in 2004 we discovered a new asteroid of 270 m long, which announced the end of the world April 13, 2029.
It was sure that day, Apophis would fall in the middle of the Pacific, causing a giant tsunami. Subsequently, the calculation accuracy indicated that Apophis in 2029 would fall closer to the Earth, a quarter of the Earth-Moon distance (90,000 km).
But if, in this April 13, 2029, it passes into a space area of 600 meters wide, called the keyhole, it could hit the Earth after its passage, April 13, 2036, with limited risk collision (impact hazard from 0 on the Torino Scale), ie zero.
We are reassured, Apophis could fall to Earth in 2036, which leaves us a little time to imagine our "defense".
But unfortunately, if it happens again in 2036 to side, it will return again and again, until it hits us.
These data will be refined in future years because they are still uncertain because the orbit of Apophis, like all other bodies, is sensitive to initial conditions that emerge from the laws of chaos. | | The orbits of the asteroids are affected by gravitational perturbations caused by other solar system bodies and thermal effects. If Apophis falls into the ocean, it will cause a wave height of the seabed, ie if the bottom is 2000 meters, the wave will be 2000 meters high.
We can easily imagine the monster arrived on the mainland coasts. It will not be a tiny tsunamis such as that of 2004 in Asia, including the wave measured only 8 meters high.
A wave of 2000 meters high can travel several times around the Earth. The power of the wave is such that this will cause earthquakes.
The destructive potential of Apophis, impresses scientists.
In Egyptian mythology, Apophis is the god of evil and destruction, the personification of chaos, seeking to destroy God's creation.
Humanity will have to postpone this god Apophis in a titanic struggle.* If Apophis falls into the ocean, it will cause a wave height of the seabed. | | 
| | | | | | | | How to avoid an impact? | | | | | | | | | | What are the possibilities to fight against this kind of disaster?
- Send the warheads on the asteroid, provided that we manage to position the device correctly in the right direction to blow up the object, but the debris does not they will be more destructive than the object itself, plus nuclear radiation would reach us.
But if the asteroid is iron, it will not be possible to break out.
- Push the asteroid landing on the object with a engine powerful tractor, then push it to vary its orbit. Must still gently push in the right direction from its center of gravity, and this well in advance.
This is possible provided you have the time and resources to build vessels (normal and emergency).
- Send an artificial satellite orbiting the rock to deflect it but slowly a few decades before to send it or you will. Must still be sure that this drive does not produce the opposite effect, ie that the object is brought back to Earth so that initially it would have avoided the Earth. | | - Even more unbelievable and wacky, to paint the meteorite in white, hoping that the light rays (photons) from the Sun will do the job for us and away from our orbit. It seems that more paint is white and the strength of the photon is "great", with little chance the asteroid will wander elsewhere.
- Bombing with a laser or other oven space to move the asteroid a few tens of meters which is enough to change its orbit. The most complex of these scenarios, will be the overall agreement on which humanity must agree to implement considerable resources. If the countdown was launched, it will be necessary to organize a response for a 500 m asteroid falling on Earth, sweeping the continent on which it falls and switch all the people on the other side of the Earth, is impossible.
Fortunately, a wide-ranging impact only occurs every 25 000 years!
* "No one knows the day nor the hour."
Gospel according to Saint Matthew. | |
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| Astronomie - 5 juin 2008 |
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