110 years ago, the Tunguska meteorite fell, the largest impact event in recent history. This anniversary once again reminded us that the meteor threat to the Earth is quite real. Worldwide, reports of asteroids passing near the Earth have begun to be remembered. If our planet is threatened by a collision with a large space body, can we protect it from space Armageddon?
Hostile environment
Space isn't that empty. Astronomers have already discovered one hundred million small bodies, and the estimated number of asteroids and meteoroids "caliber" over twenty meters reaches six hundred million. And each of them is able to cause more damage in a collision with the Earth than a 17-meter Chelyabinsk "shell", the explosion of which was equivalent to "only" 400 kilotons of TNT.
Luckily, most large asteroids rotate behind the orbit of Mars. The small bodies of the Apollo, Aton, and Amur groups, whose orbits cross the Earth's orbit, are of the greatest concern.
Only 800 atons have been detected, and a collision with them is possible only when the Earth is in the perihelion - at a minimum distance from the Sun. But they are insidious - they sneak up on the side of the luminary, appearing in the starry sky only immediately after sunset or at dawn. Amurs that threaten the planet when the apelium (the maximum distance from the Sun) passes can be seen well, but what is seen is not pleasing.
If apollo and atoms are trifles, then among 3600 already discovered asteroids of the Amur group the diameter of four bodies exceeds ten kilometers, and one - (1036) Ganymede - reaches as much as thirty-two kilometers in cross-section.
Several thousand asteroids have been identified as "potentially dangerous". And the list is probably not complete. How many asteroids have not yet been found! How many comets hide on the borders of the system, millions of years waiting far beyond the reach of earthly telescopes to rush to the sun in due time, accelerating in free fall!
Space is full of surprises.
Monitoring
The space control service, which has been under discussion since the 1990s, would avoid surprises. But so far we have only one of the most important components of the system. Modern telescopes allow us to be sure that bodies over one hundred and fifty meters across between Mercury and Mars will not go unnoticed.
But that's not enough. First, the resolution needs to be increased by an order of magnitude in order to track smaller objects as well. After all, the main danger is posed by small projectiles like the Chelyabinsk projectile, which explodes in the Earth's atmosphere every ten years or so.
Second, ground and orbital observatories themselves, which automatically track moving light and heat sources in the starry sky, are not very useful. Computer centers cannot cope with an avalanche of data. Even in general terms, the orbit can be calculated for less than one-hundredth of the detected bodies. And so far there is no reason to hope that the progress of electronics will solve the problem. In astronomy, the volume of necessary calculations grows faster than the productivity of counting machines!
In order to create an effective asteroid defense, humanity will first need more advanced mathematics. Over the past two centuries, all sciences have made a fantastic leap forward - except mathematics, which in many ways remained at the level of the XIX century and no longer meets the needs of natural disciplines.
Even the problem of gravitational interaction of the three bodies, except in special cases, has only a rough solution. An asteroid, on the other hand, interacts simultaneously with many sources of gravitation. Therefore, for small bodies of the solar system, only an approximate calculation of trajectories is possible.
Cosmic rocks are "lost" time and again, appearing not where they were expected. Asteroid orbits are unstable and can suddenly change. For example, the movement of Tauthatis - an elongated asteroid, probably consisting of two weakly bound bodies two and a half kilometers long - is called "chaotic" by astronomers. Simultaneously being in resonance with the Earth and Jupiter, the asteroid behaves unpredictably.
Even if a body threatening the Earth is detected in time, the accuracy of the calculations so far only allows us to speak of a certain probability of collision. And this is not enough. After all, the hypothetical possibility of a catastrophe is not an excuse to do anything about it. By the time the fears turn into confidence, it may be too late to shoot.
To be continued...