Yaroslav RENKAS, (c)
The international conference Asteroid-Comet Hazard 2009 that attracted 150 scientists and specialists from twenty states was held in October 2009 in St. Petersburg. They discussed the theory of movement of small cosmic bodies, assessed risks of their collision with the Earth*, analyzed methods of monitoring of dangerous objects and response measures to prevent probable cataclysms, taking into account international legal regulations and cooperation of various countries and nations. All these issues were discussed by Andrei Finkelstein**, RAS Corresponding Member and Director of the RAS Institute of Applied Astronomy, in an interview with Alexei Strigin, a correspondent of the Rossiiskaya gazeta newspaper.
First of all, he refuted the position of some journalists in relation ofr representatives of science, who allegedly exaggerate the problem of asteroid-comet hazard in order to draw public attention and get additional financial support from the government. According to the scientist, such suggestions have no grounds, as professional astronomers consider it necessary to inform public at large about all results of their studies, as opposed to the position of some UNO representatives, who work in special research committees engaged in the studies of small celestial bodies.
As for concrete facts of collision of the Earth with asteroids, they are numerous. For example, a lot of people remember the event associated with the fall of the Tunguska meteorite*** in June 1908 in Western Siberia, the power of which was 2,000 times higher than the explosive power of the American atomic bomb dropped on Hiroshima in 1945. In 1937, the Hermes asteroid (1.5 km in size) flew 750,000 km away from the Earth, then it was "lost" and "rediscovered" only in 2003. In 1989, it crossed the orbit 6 hours before our planet entered that area. Then, in 1994, the Shoemaker-Levy comet collided with the Jupiter and we witnessed the great catastrophe. In 1996, one of the asteroids flew about 470,000 km away from the Earth and was discovered by scientists only four days prior to its closest proximity to the Earth. In 2002, one more similar "guest" flew past the Earth at the same distance and was identified by scientists, when it was already moving away from the planet.
These and many other facts convincingly indicate that collisions between small cosmic bodies and Solar system planets are a common phenomenon. Besides, their occurrence is rather unexpected and we should do everything not to allow these dangerous "guests" to catch us unawares...
The appropriate monitoring equipment is successfully developing, which makes it possible to get new data on cosmic bodies, first of all, data on the most dangerous objects exceeding 100 m in diameter. They are practically not destroyed in the earth's atmosphere. The fall of such a body to the Pacific Ocean may provoke a wave of
* See: A. Mikisha, M. Smirnov, "Menace from Space: Can It Be Averted?", Science in Russia, No. 4, 2001.-Ed.
** See: A. Finkelstein, "Astronomy: March Triumphant", Science in Russia, No. 3, 2009.-Ed
*** See: E. Galimov, M. Nazarov, "Centennial of the Tunguska Event", Science in Russia, No. 3, 2008.-Ed.
Asteroids Gaspra and Ida (A, B) from the main asteroid belt.
over 100 m, which is able to cover Australia, Southwestern China and the Maritime Territory. Asteroids of 1km in diameter are capable of triggering a continental catastrophe, while cosmic bodies of several kilometers in diameter can cause a planetary disaster.
The Apophysis asteroid, discovered in 2004, is one of the most dangerous cosmic bodies known to the scientists. Its size is 300-400 m in diameter. In April 2029, it will approach the Earth to a distance of 36,000 km and will be seen with the naked eye. In 2032, it will approach the Earth for the second time to a safe distance—that is why probability of collision with our planet will be negligible-less than 0.004 percent. But here we must point out that if the asteroid passes as if through two "keyholes" (700-1,500 m each) during its first approach to the Earth, the gravitational field of the planet will change its orbit and it will without fail collide with the Earth. Though, this scenario is almost impossible, as the probability of getting into the "keyholes" is less than a hundredth percent.
Among other potentially dangerous cosmic bodies are: asteroid 2006 HZ5116 in 2045 and 2065, and asteroid 2004 VD17 in 2102-2104.
This brings up a question: is it possible to defend the planet? According to Andrei Finkelstein, modern science offers a number of methods to eliminate this danger. For example, to redirect the orbit of a cosmic body by means of a blow with a special space vehicle or with the help of solar sail sweepers or destroy dangerous bodies by atomic explosions. But all offered methods are far from a real engineering design, as it requires exact data on the orbit of this or that threatening celestial body. Therefore, the scientist concludes, the top priority task today is a constant monitoring of dangerous cosmic bodies, timely calculation of their orbit and assessment of collision probability. Search for the most appropriate methods of averting "uninvited guests" is only the second step in minimizing menace from space.
A. Strigin, Apophysis Will Come Through a "Keyhole", the "Rossiiskaya gazeta" newspaper, October 14, 2009
Опубликовано на Порталусе 19 августа 2021 года
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