Employees of the Department of Celestial Mechanics and Astrometry NII PMM of Tomsk state university (Russia) and colleagues from St. Petersburg State University, Keldysh Research Center, and Research Institute Sirius are developing measures to protect the Earth from potentially dangerous celestial bodies. With the help of supercomputer SKIF Cyberia, the scientists simulated the nuclear explosion of an asteroid 200 meters in diameter in such a way that its irradiated fragments do not fall to the Earth.
"The way we propose to eliminate the threat from space is reasonable to use in case of the impossibility of the soft disposal of an object from a collision in orbit and for the elimination of an object that is constantly returning to Earth," says Tatiana Galushina, an employee of the Department of Celestial Mechanics and Astrometry. "Previously, as a preventive measure, it was proposed to abolish the asteroid on its approach to our planet, but this could lead to catastrophic consequences -- a fall to Earth of the majority of the highly radioactive fragments."
TSU scientists with colleagues from other research centres have offered another solution to the problem. It is known that the majority of dangerous objects pass close to Earth several times before the collision. Therefore, there is a possibility to blow up the asteroid at the time when it is farther from the planet. This measure will be much more effective and safer.
For computer modeling as a potential target was taken a celestial body with a diameter of 200 meters, similar to the asteroid Apophis, which in 2029 will approach Earth at a distance of 38,000 kilometers. Calculations have shown that for the destruction of the object there must be the impact of a nuclear device with energy of one megaton of TNT equivalent. In this case, part of the asteroid turns into gas and liquid droplets, and some will break into pieces no larger than 10 meters. This is the maximum in terms of safety for the Earth.
"Because the rocket catches behind the asteroid, almost all the pieces after the destruction will fly forward," says Tatiana Galushina. "In this case the orbit of the fragments will be significantly different from the asteroid's orbit. For 10 years after the explosion an insignificant number of fragments will fall to Earth. Their radioactivity during this time will be reduced considerably, and after a few years they will not pose a danger. It is worth adding that nuclear explosions in space are prohibited by international treaty, but in the case of a real threat to humanity maybe there will be an exception to this rule."
Specialists from different areas who are experts in celestial mechanics and ballistics worked on the project. The scientists note that the theoretical calculations are only the beginning of the work, without which the practical implementation on the preventive measures protecting the Earth is impossible.
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