This month close to Earth passed a relatively small asteroid, which was discovered, within six days before. Sounds scary, but the fact is that a possible collision of this object with the Earth — an extremely unlikely event. Every year more than 50,000 tons of extraterrestrial material (rocks and dust) has on our planet. All of this comes in the form of tiny pieces — even if it all fell at the same time, it would be little more than an asteroid the size of a truck that passed in January.
But at the time, as scientists easily notice quite a lot of asteroids more than a kilometer in diameter, what is the risk can imagine the smaller asteroids, which would be harder to track? Should we be worried?
It is widely believed that the dinosaurs were wiped out 65 million years ago in the fall of a large asteroid. The ensuing environmental changes — the rapid rise in atmospheric temperatures, wildfires worldwide, then a sharp drop in temperature and acidification of ocean waters — was a consequence of the size of the asteroid. Most likely, in diameter it was about 10 kilometers.
This is almost three times larger in diameter and about 30 million times heavier than the entire annual supply of asteroids hitting us today.
Five years ago, the Earth was meeting with the object 20 meters in diameter that exploded over Chelyabinsk in Russia. No one saw it coming. Stunning footage of the fireball was recorded on DVRs people were traveling to work that morning. They were shocked at how dark February morning dawned not the rocket, not meteor.
Rock exploded in the atmosphere, and many fragments of the meteorite scattered across the territory. The biggest piece weighing 600 kilograms was found after a few months the lake is covered with ice. Although many people were injured, mostly trauma were associated with broken Windows as a result of atmospheric shock waves.
Residents of the Chelyabinsk region was in luck — the asteroid collapsed 30 kilometers above the surface and left no crater. Fortunately, as often happens.
The crater in the collision is formed only in the case if the asteroid is in diameter of over 50 meters. And even if it is 2-3 kilometers wide, this will not be enough to cause global extinction. Of course, at the point of impact will have serious problems, especially if it will be in a populated area.
Monitoring of threats
There are several international monitoring programmes, which uses automatic telescopes specifically designed to map all near-earth objects (NEO). Among them, the asteroids approaching the Sun closer than 1.3. E. — 1. E. = the distance from the earth to the Sun. Special attention is removed “potentially hazardous objects” near-earth objects 150 meters in diameter whose orbits cross earth’s orbit.
Fortunately, virtually all these objects are in stable orbits and are not dangerous. Today we can observe the asteroids even five meters in diameter. But as the event in Chelyabinsk, these objects still manage to slip past observers. Part of the reason that the Chelyabinsk object was unnoticed, is that he went under a very low angle into the atmosphere from the sun. But the main reason is that such objects are many, and we’re watching them not so long ago (about ten years).
Minot Planet Center maintains a database of observations, which at the end of December 2017 was 17 500. 28 objects were discovered this month. Our planet is surrounded by a whole swarm of possible intruders, but we keep them at a distance.
One of the main problems of our civilization is that although we all better find NEO, we can’t do anything to prevent a collision thereof with the Ground. NASA is currently developing a project called DART (Double Asteroid Redirection Test), to redirect threatening asteroids in time. The spacecraft length of 1.5 meters will be able to crash into an asteroid, for example, Didymos Didymos B. B revolves around A. Dydimos the aim of the project is to change the orbit Dydimos B around his partner, not changing A Dydimos orbit around the sun.
DART will be launched in December 2020, and with an asteroid will occur in October, 2022. Less than five years before we know whether we will be able to defend their planet from the real threat.
Today, even small asteroids can pose a threat, this threat is local and less dangerous than the one posed by large asteroids. Therefore, there is no need to collect matches and salt in the event of an attack asteroids. 50,000 tons of space material falls to Earth each year, mostly falls in the form of particles less than a millimeter in diameter. The threat to mankind they represent.