Mathematics – Logic
Scientific paper
Jan 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000cem..conf..120l&link_type=abstract
Catastrophic Events and Mass Extinctions: Impacts and Beyond, p. 120
Mathematics
Logic
Asteroids, Collisions, Meteoroid Hazards, Hypervelocity Projectiles, Projectile Cratering, Meteoritic Damage, Biological Evolution, Cometary Collisions, Meteorite Craters
Scientific paper
In the last decade the asteroid or comet impact hazard have come to be "'discovered' by the human society in parallel with many other problems that might threaten the future of civilization. The new data about small bodies of the Solar system, discovery of more and more of the geological structures on the Earth associated with catastrophic impacts of large asteroids, Shoemaker-Levy comet's crash into Jupiter in July 1994, all these provide dramatic evidence of the potential danger to humanity if a large cosmic body strikes the Earth. The problem of asteroid hazard has been transformed from a theoretical curiosity into very distinct reality and therefore the awareness of the threat to civilization from asteroid/comet impacts has increased. It is becoming more clear that collisions of large asteroids or comets with the Earth played a very important role in the evolution of life in the past, and perhaps such impact events would become a turning-point in the evolutionary history of the Earth's life in the future. The major role in this process belongs to the population of near-Earth asteroids (NEAs) in unstable orbits which can approach or cross the Earth's orbit. More than 800 Earth-approaching and Earth-crossing asteroids (ECAs) have been discovered so far. Physical characteristics of these objects are on the average identical to those of the main-belt asteroids of comparable sizes. They have similar compositions, the same optical properties, similar shapes and the axis rotation. The principal differences of NEAs from main-belt asteroids are in their orbits and relatively small sizes. The largest NEA 1036 Ganymed is about 38 km in diameter though it belongs to the Amor-group asteroids which only approach the Earth's orbit. The largest among Earth-crossers is 1866 Sisyphus with diameter of eight kilometers. In the last years the NEAs are the subject of particular interest of scientists. From the point of view of fundamental science the problem of the NEAs origin, the mechanisms of transformation of their orbits into the Earth-approaching ones, their life-time, relationships with other small bodies of the Solar system (comets and meteors) etc., are very important for the solution of the basic problem of the nearest space studies, that is the origin and evolution of our planetary system. On the other hand, during the recent years the studies of NEOs have also acquired important applied significance. These objects are believed to be the potential sources of metals and other raw materials in the near-Earth space. Finally, the problem of asteroid impact hazard arouses the increasing interest in studies of these objects nowadays. This danger has existed over all periods of the Earth 's history, however the realization is coming only now. Additional information is contained in the original extended abstract.
Lupishko Dmitrij F.
Lupishko T. A.
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